What is a polysaccharide? Application of polysaccharides and their significance. Polysaccharides Polysaccharides are made up of residues of

(molecular weight from several thousand to millions), the molecules of which consist of monosaccharide residues (see). They are colorless, amorphous substances, most of which swell easily in water, forming viscous colloidal solutions. Polysaccharides are widespread in nature (the most common is cellulose, a component of wood). Starch and some other polysaccharides are formed in plants during photosynthesis. During acid or enzymatic hydrolysis, polysaccharides break down into simple sugars - monosaccharides.

In living organisms, polysaccharides serve as an energy reserve (glycogen in animals, starch in plants), and serve as supporting elements (chitin in insects and crustaceans, cellulose in plants). Polysaccharides such as mucopolysaccharides (see) are natural anticoagulants (see) (for example, heparin) or perform some special functions. Polysaccharides, especially starch, are important constituents of food products. Many polysaccharides serve as raw materials: starch - in the food, pharmaceutical industries, etc., cellulose - for the production of fibers. Physiologically active polysaccharides - heparin (see), dextrins, gums - are used in medicine.

See also Mucopolysaccharides, Carbohydrates.

Polysaccharides (synonym: complex sugars, polyoses, glycans) are carbohydrates whose molecules consist of several residues (from two to several thousand) of the same or different monosaccharides or substances close to them (deoxy sugars, amino sugars, uronic acids, etc.).

General formula of the most common polysaccharides: CnH2mOm

All P. are constructed according to the type of glycosides (see): the hydrogen atom in the hemiacetal hydroxyl of one monosaccharide molecule is replaced by a second monosaccharide molecule, the hydrogen atom in the hemiacetal hydroxyl of the second molecule is replaced by a third molecule, etc.

As a result, for any number of monosaccharide residues in the polyglycoside molecule, only one free hemiacetal hydroxyl usually remains (the “aldehyde” or reducing “beginning” of the polyglycoside chain).

One polyglycosidic chain can be attached through the oxygen of its hemiacetal hydroxyl to any of the intermediate monosaccharide residues of another polyglycosidic chain; This is how branched P.s arise.

Different polysaccharides differ in the degree of polymerization, i.e., in the number of monosaccharide residues in the molecule; depending on this, they distinguish: a) oligosaccharides containing from 2 to 9 monosaccharide residues (disaccharides, trisaccharides, etc.) with a small mol. weight, highly soluble in water, with a sweet taste - P. sugar-like; b) higher polyoses, usually containing several hundred and even thousands of residues, high-molecular substances, poorly soluble or insoluble in water, and without a sweet taste.

Polysaccharides differ in the presence of the same or different monosaccharide residues [homopolysaccharides (for example, glycogen, fiber, otherwise cellulose, amylose consist of glucose residues; chitin - from glucosamine; pectic acid - from galacturonic acid) and heteropolysaccharides (for example, hemicelluloses, gum acacia, many bacterial polysaccharides)].

The presence of a straight polyglycosidic chain (as in amylose, cellulose) and to one degree or another branched (amylopectin, glycogen) also serves as a sign of differences in P. Finally, polysaccharides are distinguished by the presence of pyranose or furanose rings (in inulin), by the presence of the α-configuration of monosaccharides residues (amylose), β-configuration (cellulose) or both configurations (guarane) and by the presence of certain glycosidic bonds connecting the first carbon atom of one residue with the fourth or other carbon atoms of another residue, for example α-1 bonds, 4 (amylose), β-1,4 (cellulose), α-1,6 (dextran), etc.

In many cases, P. molecules contain different glycosidic bonds. Based on their origin, polysaccharides are divided into plant, animal, and microorganisms (bacteria and fungi).

Being polyglycosides, P. undergo hydrolysis - acidic or enzymatic. Since free alcohol hydroxyls remain in each monosaccharide residue, polysaccharides can form compounds such as ethers and esters, which are important for identification, establishment of structure (methyl esters), and also as substances important in practice (for example, fiber esters).

Such higher foods as starch and a number of oligosaccharides (sucrose, lactose) are of important nutritional value. Many P. play the role of energy reserves of organisms: glycogen (see) in animals, starch and other polysaccharides in plants.

A number of polysaccharides [cellulose (fiber) in plants and chitin in some animals - crustaceans, insects] play an important supporting role. Many P., especially mucopolysaccharides (see), containing residues of amino sugars and often uronic acids, perform important highly specialized functions [for example, heparin is a natural anticoagulant, hyaluronic acid (see) has barrier functions, blood group mucopolysaccharides (the so-called group-specific P.) and tissues determine their specificity]. Many P. have antigenic (immune-inducing) properties (immune-specific P.). A number of polysaccharides are used as honey. drugs: dextran (see), heparin (see), etc.

Many P. are of great technical importance, for example, cellulose, dextrins, and pectin substances, which are derivatives of polygalacturonic acid.

For use in medical practice K. Subsequently, when studying plants, they switched to analysis through extracts. Alkaloids are nitrogen-containing organic substances of natural origin. In medical practice, they are used as a basis for preparing various ointments and obtaining oil extracts from plant materials.

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INTRODUCTION

Since time immemorial, scientists have believed that plants contain special substances, which they called "active principles." For use in medical practice, C. Galen extracted active principles from plants using wine, vinegar, honey or their aqueous solutions. Paracelsus raised the issue of active ingredients especially acutely and recommended extracting them only with ethyl alcohol (modern tinctures and extracts).

In an effort to obtain the active principles of plants, scientists have tried a variety of methods. Subsequently, when studying plants, they switched to analysis through extractions. Around 1665, I. Glauber obtained “improved plant principles” in the form of powders from many poisonous plants using aqueous solutions of nitric acid. Now these substances are called alkaloids. In addition to alkaloids, other active substances were discovered that somehow affect the human body.

Alkaloids are nitrogen-containing organic substances of natural origin. In plants, alkaloids are often found (a mixture of several alkaloids) in the form of salts of organic and inorganic acids. The most widespread alkaloids are caffeine, atropine, echinopsine, strychnine, cocaine, berberine, papaverine, etc.

Glycosides are complex nitrogen-free compounds consisting of sugar and non-sugar parts. Among the glycosides, cardiac glycosides, anthraglycosides, saponins and other substances are distinguished. Glycosides affect the heart, gastrointestinal tract, etc.

Flavonoids are heterocyclic oxygen-containing compounds of yellow color, poorly soluble in water, possessing various biological activities. They enter the human body only with plant foods.

Tannins are complex substances derived from polyhydric phenols that have the ability to coagulate adhesive solutions and produce insoluble precipitates with alkaloids. They are widely distributed in almost all plants.

Essential oils are a mixture of volatile, nitrogen-free substances with a strong characteristic odor. They have antimicrobial, analgesic, antitussive, anti-inflammatory, choleretic and diuretic effects.

Vitamins are organic compounds of various chemical structures that are necessary for the normal functioning of almost all processes in the body. Most of them enter the body with plant and animal foods.

Fatty oils are esters of glycerol and high molecular weight fatty acids. In medical practice, they are used as a basis for preparing various ointments and obtaining oil extracts from plant materials. Some of them, such as castor oil, have a laxative effect.

Microelements are substances that, together with vitamins, participate in vital processes occurring in the body. Their imbalance can lead to the development of serious diseases.

Polysaccharides are complex carbohydrates; a numerous and widespread group of organic compounds that, along with proteins and fats, are necessary for the life of all living organisms

They are one of the main sources of energy generated as a result of the body's metabolism. Polysaccharides take part in immune processes, provide cell adhesion in tissues, and constitute the bulk of organic matter in the biosphere.

1. Polysaccharides. Their characteristics

The diverse biological activity of polysaccharides of plant origin has been established. They have antibiotic, antiviral, antitumor, antidote, antilipemic and antisclerotic activity. The antilipemic and antisclerotic role of plant polysaccharides is due to their ability to form complexes with proteins and lipoproteins in the blood plasma.

Some Soviet pharmacologists (A.D. Turovan, A.S. Gladkikh) believe that the most promising direction in the study of polysaccharides is the study of their effect on viral diseases, on the course of peptic ulcers and gastritis.

Polysaccharides include: gums, mucus, pectin, inulin, starch, fiber.

Comedy - this is a thick slimy sap that protrudes either randomly or from cuts and wounds on the bark of many trees. In a living plant, gums are formed through a special mucus degeneration of the fiber of the parenchyma cell membranes, as well as the starch located inside the cells.

In many plants, gums are formed in small quantities normally, physiologically, but the abundant formation of gum is considered as a pathological process, arising as a result of injury and leading to the filling of the resulting wound with mucus.

The resulting gums are not involved in the general metabolism of plants. In appearance, gum preparations are usually round or flat pieces, for some types of gum they are very characteristic, transparent or only translucent, colorless or colored brown; have no odor, no taste or a weak sweetish mucous.

Some gums dissolve in water, forming colloidal solutions, others only swell. Insoluble in alcohol, ether and other organic solvents. Chemically insufficiently studied.

They consist of polysaccharides with calcium, magnesium and potassium salts of sugar gum acids. These are cherry, apricot, almond, plum glue, acacia gum, or gum arabic. Gum acacia has activity similar to ACTH. The mechanism of their action is different.

Slime - These are nitrogen-free substances similar in chemical composition to pectin and cellulose. It is a viscous liquid produced by the mucous glands of plants and is a solution of glycoproteins. Slime is formed in plants as a result of physiological disorders or various diseases, as a result of which the membranes and cellular contents die. The outer layers of algae cells, seeds of plantain, quince, flax, mustard, as well as the inner layers of underground organs - marshmallow, orchis (salep) - are capable of sliming. The beneficial effect of mucilages is that they protect the plant from drying out, promote seed germination and their distribution.

Mucus has a semi-liquid consistency and is extracted from the raw material with water. They belong to the group of neutral polysaccharides and are a complex mixture of different chemical compositions. They are based on sugar derivatives and partially potassium, magnesium, and calcium salts of uronic acids.

Mucus and gum are so similar that it is not always possible to differentiate between them. Mucus, unlike gum, is not obtained in solid form, but by extraction with water. Mucous substances help slow down the absorption of drugs and their longer action in the body, which is of great importance in therapy.

Pectins (from the Greek pectos - thickened, curled) are close to gums and mucus, and are part of the intercellular adhesive substance. Widely distributed in the plant world. Water-soluble pectins are of particular value. Their aqueous solutions with sugar in the presence of organic acids form jellies that have an adsorbent and anti-inflammatory effect.

Pectin substances are a group of high-molecular compounds that are part of the cell walls and interstitial substance of higher plants. The maximum amount of pectin is found in fruits and root vegetables.

Pectic substances were discovered by Braconno in 1825. However, despite the fact that their study has continued for more than a hundred years, the chemical structure of these compounds was clarified only in the second half of the 20th century. The reason for this is the difficulty of obtaining pure preparations of pectin substances in an unchanged state.

Until the 20th century it was believed that the neutral sugars arabinose and galactose take part in building the chain of pectin substances, but in 1917 it was found that they have a structure similar to cellulose, that is, they consist of galacturonic acid residues connected into long chains using glycosidic bonds. Since the 1970s Many foreign scientists, based on their research, have concluded that pectin substances are a complex group of acidic polysaccharides that may contain a significant amount of neutral sugar components (L-arabinose, D-galactose, L-rhamnose).

Pectins are widely used in various sectors of the national economy, especially in the food industry, where they are used as thickening agents for the production of jams, jellies, and marmalade; in baking - to prevent baked goods from becoming stale; in the production of sauces and ice cream - as an emulsifying agent; when canning - to prevent corrosion of tin cans, etc.

The use of pectins in medicine is extremely promising. Pectin (the gelatinous substances of plants) bind strontium, cobalt, and radioactive isotopes. Most pectins are not digested or absorbed by the body, but are excreted from it along with harmful substances. Strawberries, rose hips, cranberries, black currants, apples, lemons, oranges, viburnum, etc. are especially rich in pectins.

Inulin - a polysaccharide formed by fructose residues. It is a reserve carbohydrate in many plants, mainly Asteraceae (chicory, artichoke, etc.). Used as a starch and sugar substitute for diabetes mellitus, a natural component obtained from plant roots.

Inulin is used in the form of dietary supplements (drops, tablets) for the prevention and treatment of various diseases. It has no contraindications. Preparations containing inulin are especially valuable for diabetics. Natural fructose, which inulin contains, is a unique sugar that completely replaces glucose in cases where glucose is not absorbed. Therefore, the dietary value of inulin is great.

Starch - the end product of carbon dioxide assimilation by plants. It is deposited mainly in tubers, fruits, seeds and the core of the stem. In the body, glucose is formed from starch. We get starch from plants, where it is found in the form of tiny grains.

Plants accumulate starch in small grains in trunks and stems, roots, leaves, fruits and seeds. Potatoes, maize, rice and wheat contain large amounts of starch. Plants produce starch to serve as food for young shoots and shoots until they are able to produce their own food.

For humans and animals, starch represents an energy-dense food. Like sugar, it is composed of carbon, hydrogen and oxygen. Unsweetened starch: It is usually tasteless. Certain chemicals in the mouth, stomach and intestines convert starchy foods into grape sugar, which is easily digested. A person obtains starch from plants by grinding those parts where it accumulates. Then the starch is washed out with water and settles to the bottom of large containers, after which the water is squeezed out of the raw starch, the mass is dried and ground into powder, in the form of which starch is usually made. Starch does not dissolve in cold water, but in hot water it forms a viscous solution, which turns into a gelatinous mass when cooled. In diluted form, it is used as an enveloping agent for gastrointestinal diseases (raw potato juice, jelly). Tubers, roots, rhizomes, and bark are rich in starch, where it accumulates as a nutrient depot. Since chicory, dandelion roots and elecampane tubers contain inulin in addition to starch, these plants are used to treat diabetes.

Fiber or cellulose, is the main component of plant cell walls and is a complex carbohydrate from the group of non-sugar-like polysaccharides. Previously, it was believed that fiber was not digested in the intestines. Recently, it has been found that some types of fiber are partially digestible. Fiber is the roughest part of the plant. This is a plexus of plant fibers that make up cabbage leaves, the skins of legumes, fruits, vegetables, and seeds. Dietary fiber is a complex form of carbohydrates that our digestive system is not able to break down. But it is one of the most important elements of human nutrition. Dietary fiber reduces the residence time of food in the gastrointestinal tract. The longer food stays in the esophagus, the longer it takes to be eliminated. Dietary fiber speeds up this process and at the same time helps cleanse the body. Consuming enough fiber normalizes intestinal function.

2. Mechanism of action of polysaccharides

Despite the differences in production methods, the chemical structure of polysaccharides is characterized by close manifestation of physiological effects: sorption of radionuclides, heavy metals, bacteria and bacterial toxins, normalization of lipid metabolism in hyperlipidemia of various etiologies, activation of the secretory and motor function of the intestine, regulation of immunity, modulation of the endocrine system, optimization of the functioning of the hepato-biliary system.

Polysaccharides have a direct effect on the tissue structure and function of the gastrointestinal tract, liver, kidneys and other organs, which has been identified at the biochemical and morphological level. In addition, polysaccharides affect tissues and organ systems that do not come into direct contact with them when administered orally, intravenously, intraperitoneally, or subcutaneously into the body.

The physiological and metabolic aspects of the influence of polysaccharides on the liver against the background of pathology have been most studied. The need to uncover the fundamental principles associated with the physiological effect of polysaccharides under normal conditions and diseases of various etiologies is relevant for their use in practical medicine.

Here is how Dr. S. Aleshin describes the mechanisms of action of polysaccharides: “Unfortunately, the immune system does not work perfectly as we would like. Viruses, especially with hepatitis B and C, use various tricks to lull the vigilance of the immune system. cancerous tumors that resort to numerous techniques to deceive the immune system. Therefore, very often in these conditions, the immune system resembles a dormant watchman, not noticing how the damage and destruction of the body occurs. Fungal polysaccharides, entering the body, activate the immune system, which exits. from a sleeping state and begins to actively fight, tearing off the disguise from his enemies."

Pectins and pectin-containing products entering the digestive tract form a sticky substance that very easily binds to many metals, primarily lead, strontium, calcium, cobalt, as well as other heavy metals and radioactive substances that are not able to be absorbed into the bloodstream. By this, pectins protect the body from radioactive substances and heavy metal salts that penetrate into the human body with food and water.

Polysaccharides activate hepatic-intestinal circulation and remove excess cholesterol from the body. Therefore, polysaccharides play an important role in the prevention of atherosclerosis.

The mucous substances of some plants, after ingestion, form protective covers on the surface of the mucous membrane of the gastrointestinal tract and thereby protect them from irritation by toxins, drugs, etc.

Pectins enhance intestinal motor function and prevent constipation.

The therapeutic effect of mucus is due to the protection of the nerve endings of the gastrointestinal mucosa from the irritating effects of other substances.

Polysaccharides increase the activity of the cilia of the ciliated epithelium of the respiratory tract, which leads to increased secretion of bronchial mucus, as a result of which the sputum thins and makes it easier to separate when coughing.

3. Medical and biological significance of polysaccharides contained in plants

The medical and biological significance of polysaccharides is varied. Many of them (starch, glycogen, inulin, etc.) are reserve nutrients in plant and animal organisms. Some polysaccharides (for example, chondroitinsulfuric acid, capsular polysaccharides and fiber) have exclusively supporting and protective functions.

A number of polysaccharides (mannaps, galactans, etc.) are used both as building and nutritional materials. Hyaluronic acid, which makes up the intercellular substance of animal tissues, along with its structural function, regulates the distribution of vital substances in tissues. Heparin prevents blood clotting in humans and animals. In many cases, polysaccharides form very strong complexes with proteins, forming glycoproteins that perform a number of important functions in the body.

Recently, interest in plant polysaccharides has increased due to the fact that these compounds, previously considered inert, have a wide range of pharmacological activities.

Medicinal plants containing polysaccharides are used as expectorants, enveloping agents, diaphoretics, and laxatives. Medicines used as wound-healing and anti-inflammatory drugs are obtained from polysaccharides. The possibility of using polysaccharides as blood-substituting solutions has been confirmed.

Grape, currant and blueberry pectins have significant antifibrinolytic activity. Alginates also provide a pronounced hemostatic effect.

The diverse biological activity of plant polysaccharides has been established: antibiotic, antiviral, antitumor, antidote. Polysaccharides of plant origin play an important role in reducing lipemia and vascular atheromatosis due to their ability to form complexes with proteins and lipoproteins in blood plasma.

Inulin serves as a storage carbohydrate and is found in many plants, mainly the Asteraceae family, as well as Campanaceae, Liliaceae, Lobeliaceae and Violetaceae.

In the tubers and roots of dahlia, narcissus, hyacinth, tuberose, chicory and Jerusalem artichoke, scorzonera and oat root, the inulin content reaches 10-12% (up to 60% of the dry matter content).

Inulin lowers sugar levels, prevents complications of diabetes, and is also used for obesity, kidney disease, arthritis and other types of diseases. It has a positive effect on metabolism. Inulin removes a lot of harmful substances (heavy metals, toxins) from the body, reduces the risk of cardiovascular diseases, and strengthens the immune system.

Part of the inulin is broken down in the body, the unsplit part is excreted from the body, carrying with it a lot of substances that the body does not need - from heavy metals and cholesterol to various toxins. At the same time, inulin promotes the absorption of vitamins and minerals in the body.

In addition, inulin has an immunomodulatory and hepatoprotective effect, counteracting the occurrence of cancer. To enhance the effect of inulin in dietary supplements, it is combined with the juices of other natural healers, such as celery, parsley, sea buckthorn, rose hips, viburnum, ginseng, licorice, and eleutherococcus.

Natural sources of inulin are Jerusalem artichoke, dandelion, chicory, burdock, and elecampane.

Starch is also used in medicine. It is used as a filler, in surgery for the preparation of fixed dressings, and as an enveloping agent for gastrointestinal diseases.

In pharmacy, starch is used to prepare ointments and powders. It has been established that starch reduces cholesterol levels in the liver and blood serum and promotes the synthesis of riboflavin by intestinal bacteria. Riboflavin, when included in enzymes and coenzymes, promotes the conversion of cholesterol into bile acids and their removal from the body, which is of great importance for the prevention of atherosclerosis. Starch helps intensify the metabolism of fatty acids. In children's practice and for skin diseases, starch is used as powders. A decoction is used internally and in enemas as an enveloping agent.

Plants accumulate starch in small grains in trunks and stems, roots, leaves, fruits and seeds. Potatoes, maize, rice and wheat contain large amounts of starch. Use of starch in medicine:

Gums are used to prepare oil emulsions, tablets, pills - as a binder. In medicine, raw materials containing mucus are used as an expectorant, emollient, and anti-inflammatory agent. Gums are also used as emulsifiers, coating and adhesive substances for the preparation of pills and tablets (pill mass). In medicine, gums are used as excipients in the preparation of a number of dosage forms.

Mucus and gums are used as enveloping and emollient agents due to their ability to form jellies and colloidal solutions that create a protective covering of the nerve endings of the mucous membrane of the pharynx, gastrointestinal tract, bronchioles, etc.

The biological role of mucus is as follows: as reserve substances, they protect the plant from drying out, promote the spread and fixation of plant seeds.

They are used in the treatment of gastritis, peptic ulcers, colitis, enterocolitis, poisoning with certain poisons, and respiratory diseases. Mucous substances help slow down absorption and, therefore, longer action of drugs in the body. Externally applied in the form of poultices. As mucous substances, flaxseed (5-12% mucilage), orchis tubers, chamomile, marshmallow root, salep (up to 50% mucilage), scepter-shaped mullein, tripartite string, large plantain seeds, large, lanceolate and medium plantain leaves are used, linden flowers, etc. Biological role of gums:

They protect plants from infection by microorganisms by filling the resulting cracks and other damage to the trunks.

Plant polysaccharides, in particular pectins, exhibit biological activity in relation to the basic functions of the digestive system and can be used in the form of natural complexes, on the basis of which a number of preparations have been created: “Plantaglucide” from the leaves of the great plantain, including low molecular weight pectins; "Laminarid" from seaweed as a laxative; beet pectin, included in the complex anti-ulcer drug "Flacarbin".

Polysaccharide preparations of chamomile and tansy inflorescences have been proposed as promising antiulcer drugs. In the experiment, polysaccharides from the stems of hollyhock species are superior in antiulcer activity to the effect of the drug "Plantaglucid".

Pectins, due to their acidic nature, exhibit an antimicrobial effect against gram-positive and gram-negative bacteria.

Pectins improve digestion, reduce putrefaction processes in the intestines and remove toxic metabolic products formed in the body itself; promote the production of B vitamins in the intestines, especially B12, the vital activity and growth of beneficial bacteria in the intestines, and the elimination of excess cholesterol. Pectin substances are widely used in the treatment of diarrhea. Apple pectin delays the reproduction of influenza virus “A”, reduces the effects of mercury and lead poisoning, and promotes the removal of lead from bone tissue. Currently, the apple diet, pectin and pectin substances are widely used abroad for the treatment of diarrhea and dysentery in children.

Pectins are used as a hemostatic agent. Currently, the hemostatic properties of pectins are successfully used abroad for pulmonary hemorrhages, bleeding from the esophagus, stomach and intestines, as well as for jaundice, liver cirrhosis, thrombophlebitis, gynecological diseases, dentistry and hemophilia.

The most common pectin-containing raw materials are citrus fruits (pomace), apples (pomace), sugar beets (pulp), feed watermelon, sunflower baskets, Jerusalem artichoke tubers and some other agricultural raw materials.

Fiber, mechanically acting on the nerve endings of the intestinal walls, stimulates its motor function, stimulates the secretion of digestive juices, gives porosity to the food mass, providing more complete access to digestive juices, increases the biological value of food products, normalizes the vital activity of beneficial intestinal microbes, and promotes excretion from the body toxic products of exo- and endogenous origin. And, thus, helps prevent and treat liver diseases, hypertension, atherosclerosis, normalize the bacterial flora of the intestines, stimulates the synthesis of B vitamins, especially B2, and vitamin K.

Foods rich in fiber include asparagus, broccoli, Brussels sprouts, cauliflower, celery, zucchini, cucumbers, garlic, green beans, green peppers, and lettuce. Leeks, mushrooms, peas, spinach, sprouted seeds, tomatoes. Fruits are also a great source of fiber, but they contain a lot of sugar (fructose).

Currently, more than 20 higher plants containing immunostimulating polysaccharides are known. Among them are angelica, Eleutherococcus senticosus, ginseng, calendula, safflower, chamomile, Echinacea purpurea, and Echinacea purpurea. common goldenrod, white mistletoe, yellow cornflower, high mullein, rice, bamboo, stinging nettle, Japanese sophora, American phytolacca, centaury, sorrel, clover, yucca, Cretan eryngium, Siberian larch, common burdock, autumn colchicum, stock species roses, marshmallows, etc.

Immunostimulating, including antitumor activity is due to the activation of macrophages and killer cells, increased interferon production, increased phagocytosis, increased antibody production, increased immunoglobulin levels, and a strong anti-inflammatory effect.

Polysaccharides increase the body's defenses against infection, especially viral ones, primarily in all influenza infections. Currently, the possibility of using plant polysaccharides as pharmacosanitizing drugs that help increase the body's resistance has been shown.

The antihypoxic activity of water-soluble polysaccharides and pectin substances from high mullein, common chicory, white mistletoe, ginseng, American phytolacca, and firmiana has been proven. Mistletoe polysaccharides have a pronounced radioprotective effect when exposed to g-radiation.

Under the influence of polysaccharides from common chicory and high mullein, the level of total cholesterol in the blood serum normalized and the content of alkaline phosphatase decreased, which indicates that they have a pronounced hepatoprotective effect comparable to “Silibor”. These compounds have pronounced choleretic activity. A similar effect was found in polysaccharides of burdock and dandelion. Thus, the established versatile pharmacological activity of polysaccharides allows us to consider them as a possible source of new drugs.

4. Plants containing polysaccharides

4.1 Plants containing gums

Woolly-flowered astragalus (Astragalus dasyanthus) of the legume family (Leguminosae).

Botanical description.A loosely branched shrub up to 16-40 cm high, with reddish-shaggy branches. The leaves are compound, consisting of 12-14 pairs of lanceolate or lanceolate-oblong leaflets. The inflorescence is dense capitate racemes of 10-20 flowers. The fruit is a hairy, oval bean 10-11mm long. Flowering time May-July.

Spreading.It grows wild in the steppe part of the Dnieper region, the Volga-Don basin and the Black Sea region. It also grows in the steppe and forest-steppe zones of Russia - Voronezh, Kursk, Volgograd regions, Stavropol region, Ukraine and Moldova. Prefers areas with preserved steppe vegetation. It grows in open places, in the steppe, on mounds and old cemeteries, in clearings and forest edges. It is not demanding of moisture and does not withstand moisture or shading.

Preparation and storage.The above-ground part is used - astragalus herb. The grass is cut in the flowering phase at a height of 5-7 cm from the ground. Procurement of Astragalus wooliflora raw materials in nature should be extremely reduced, since the plant is included in the Red Book.

Drying It is done quickly in attics or in well-ventilated sheds, under sheds, the grass is laid out in a layer of 3-5 cm on paper or fabric, turning over often. Drying continues for 5-7 days.

Raw materials It has straight stems, densely leafy, reddish-shaggy, with odd-pinnate leaves up to 20 cm long. The leaves consist of 11-17 pairs of oblong-oval silky pubescent leaves. The flowers are densely pubescent, with a yellow corolla, moth-like in structure, collected 10-20 in dense round racemes.

Finished raw materials are packaged in bales or bags. You can also dry astragalus raw materials in dryers at a temperature of 40 - 60 ° C. Store packaged in dry, well-ventilated areas on racks or on shelves. Shelf life 1.5 years.

Chemical composition. Astragalus wooliflora contains gum (tragacanth), which is obtained from natural cracks and cuts in the trunk. The composition of the gum includes: 60% bassorin and 3-10% arabin, which are classified as polysaccharides. It also contains starch, sugars, mucous substances, dyes, and organic acids.

Pharmacological properties. Pharmacological research on astragalus was first carried out by E.V. Popova, who showed that the plant infusion has sedative and hypotensive properties. Along with this, astragalus dilates the coronary and renal vessels and enhances diuresis.

Application. The most effective use of Astragalus wooliflora is in case of circulatory failure of I - II degree and in the treatment of acute nephritis. It is also used for hypertension and chronic cardiovascular failure.

Drugs. Infusion of astragalus herb. 10 g of herb (2 tablespoons) is placed in an enamel bowl, poured with 200 ml (1 glass) of hot boiled water, heated in a boiling water bath for 15 minutes, cooled for about 45 minutes, filtered, topped up with boiled water to the original volume - 200 ml. Take 2 - 3 tablespoons 2 - 3 times a day. Store for no more than 2 days in a cool place

4.2 Plants containing mucilage

Marshmallow (Althaea officinalis) of the mallow family (Malvaceae)).

Botanical description.A perennial velvety-silky herbaceous plant 1-1.5 m high with a short thick multi-headed rhizome and branched roots. The leaves are alternate, lobed, serrated along the edges. The flowers are pale pink, large, in a racemose-paniculate inflorescence. The fruit is fractional from 15-25 fruitlets. The seeds are kidney-shaped, dark brown, 2-2.5 mm long. Blossoms and bears fruit in July-August.

Spreading.Althaea officinalis is found in the central and southern zones of the European part of Russia, in the Caucasus, throughout Ukraine and a little in Central Asia. It usually grows in damp places, in floodplains, among bushes.

Preparation and storage. The medicinal raw material is marshmallow root. The roots are collected in spring or autumn, and the plant must be less than 2 years old. The roots are quickly washed in running cold water to avoid mucus secretion and cut into pieces. The roots are cleared of the cork layer to obtain a peeled root. The root is dried immediately after collection: first, it is dried for three days in the sun, and then dried in special dryers at a temperature of about 40 °C. If the roots have been dried correctly, they retain a whitish color and do not darken. Flowers and leaves are harvested less often.

The finished raw material can be peeled or not cleared of the cork layer, but must retain its light color. A dry root should become dusty when broken, and when water gets on it, mucus should appear on the root. The smell of marshmallow root is weak, and it can taste sweet and slimy.

Keep Marshmallow roots should be kept in a well-ventilated area, as humidity can cause the roots to become damp and moldy. In pharmacies, the root is stored in closed boxes, and the powder from the root is stored in glass jars. In warehouses it can be stored in bags of 50 or 25 kg. If stored properly, marshmallow root can be suitable for medicinal purposes for three years.

Chemical composition. Dry marshmallow roots contain mucus (35%), starch (37%), asparagine, sugars, fatty oil, carotene and minerals. The leaves and branches contain a small amount of essential solid oil.

Pharmacological properties.Marshmallow has an anti-inflammatory, expectorant or enveloping effect. Marshmallow roots contain a large amount of polysaccharides, so they have the property of swelling in aqueous infusions and covering the skin and mucous membranes with a thin layer. This layer protects the skin and mucous membranes from harmful factors such as drying out, cold or dry air, etc.

Althea has been known since ancient times. It was used already in the 7th century. BC. Then it was known as "alceus", which translated from Greek means "healing"

Application. Marshmallow roots are widely used in medical practice around the world. In a number of countries, leaves and flowers are used. Marshmallow root is used internally for respiratory diseases: bronchitis, tracheitis. The root is also used for diseases of the gastrointestinal tract: gastric and duodenal ulcers, gastritis, colitis. It also acts as a fixative for diarrhea.

Externally used in preparations as an anti-inflammatory and emollient in the form of poultices, gargles, etc.

Drugs. Infusion of marshmallow root. Finely chopped root in an amount of 6 grams is poured into 100 ml of water and left for about 1 hour. The finished infusion should be transparent and yellowish in color. It should taste sweet and slimy; has a faint peculiar odor. Take 1 tbsp infusion. l. in 2 hours

A cold infusion of marshmallow roots is prepared as follows: a tablespoon of crushed roots is poured with cold boiled water for an hour, filtered through cheesecloth, and sugar or honey is added for sweetness. Take a tablespoon every 2 hours 3-4 times a day before meals. They drink this infusion, in particular, for eczema and psoriasis.

4.3 Plants containing pectin

The fruits of cranberries, black currants, apple trees, hawthorns, chokeberries, mountain ash, barberries, plums, gooseberries are rich in pectins.

Chokeberry (Aronia melanocarpa) of the Rosaceae family.

Botanical description.Deciduous shrub up to 1.5-2.5 m high. leaves are simple, entire, serrate, obovate, alternate. The root system is powerful, superficial, fibrous, and consists of vertically and horizontally located roots. Flowers are quintuple, white or pink in corymbose inflorescences. The fruits are apple-shaped, 8-10 cm in diameter, black with a bluish coating. The skin of the fruit is dense, the pulp is almost black when ripe, the fresh juice is dark ruby ​​in color, highly colored. The seeds are dark brown, wrinkled, 2 mm long. Chokeberry is a self-pollinating plant and is almost not susceptible to disease. Blooms in May, bears fruit in September.

Spreading.Chokeberry is grown in various regions of the country as a valuable fruit and ornamental shrub. The homeland of chokeberry is the forest areas of the USA. Due to its unpretentiousness and winter hardiness, it has been introduced in almost all ecological and geographical regions of the former CIS, even in those where the cultivation of other fruit and berry crops is difficult.

Chokeberry produces stable harvests in the northern regions of the European part of the CIS, in the harsh conditions of Western and Eastern Siberia, Eastern Kazakhstan and the Urals. The costs of creating industrial chokeberry plantations in different farms across the country quickly pay off. Chokeberry is propagated by seeds, vertical and horizontal layering, dividing the bush, root shoots, green cuttings and grafting.

Preparation and storage. Ripe fruits are used. They have a pleasant sour-sweet, tart taste. Chokeberry is characterized by a number of valuable characteristics: annual good fruiting, early onset of fruiting, a long productive period, preservation of fruits after ripening on the bushes until frost, good winter hardiness, low demands on soils, responsiveness to fertilizers, good ability to reproduce. The fruits acquire the best taste in September.

Chokeberry is an exclusively light-loving crop. With dense placement of bushes or very thickening of the bush and in the absence of pruning, the yield of chokeberry fruits decreases sharply. The fruits are located mainly on well-lit peripheral branches. Aronia fruits are collected in one go in containers with a capacity of 10 - 12 kg. Amateur gardeners receive up to 15 - 30 kg of chokeberry fruits from individual bushes.

Chokeberry fruits must comply with the Pharmacopoeial article FS 42-66-72 “The fruit of chokeberry (aronia) is fresh” and the technical specifications TU 64-4-27-80 “The fruit of chokeberry (aronia) is dry.” Chokeberry fruits must be clean, fresh, with a humidity of 70 - 83%; unripe fruits no more than 2%; leaves and stem parts no more than 0.5%; fruits damaged by pests no more than 0.5%; mineral impurities no more than 0.5%; P-vitamin substances not less than 1.5%.

Fresh fruits are transported in fruit and vegetable boxes weighing up to 40 kg in refrigerators or in ordinary wagons and cars, if the journey does not exceed 3 days. Fruits are stored at collection points for no more than 3 days from the date of collection. Shelf life at a temperature not exceeding 5°C is up to 2 months.

In recent years, for ease of transportation and storage, chokeberry fruits have begun to be dried. Dried fruits must contain at least 25% extractives extracted with 20% alcohol; moisture no more than 18%. The presence of mold and rot, as well as persistent foreign odors, are not allowed. The delivered lot is allowed to contain no more than 5% of unformed, immature and pest-damaged fruits; leaves and stem parts no more than 5%; mineral impurity no more than 0.5%. The shelf life of dry fruits is no more than 2 years.

Chemical composition.The fruits of chokeberry contain a lot of vitamin P, ascorbic acid, sugar (up to 9.5%), as well as organic acids, carotene, and a lot of iodine. Flavonoids and anthacyans were detected. In terms of acid content, chokeberry fruits are significantly superior to tangerines, strawberries, raspberries, and red currants. It contains more vitamin P than other types of mountain ash.

Picked rowan fruits do not spoil for a long time, as they contain substances that suppress the proliferation of microbes. Aronia fruits contain sugars (up to 10%), malic and other organic acids (up to 1.3%), pectins (up to 0.75%) and tannins (up to 0.6%). Amygdalin, coumarin and other compounds were also found in the pulp of the fruit. Of the microelements, iron - 1.2 mg, manganese - 0.5 and iodine - 5 - 8 mg per 100 g of fruit pulp stand out.

Pharmacological properties.The fruits of chokeberry help lower blood pressure, are a good preventive and therapeutic agent for hypertension, and also strengthen the walls of blood vessels. Organic iodine compounds, found in chokeberry in sufficient quantities, remove excess cholesterol from the body and have a beneficial effect on the function of the thyroid gland. Due to the large number of substances with P-vitamin activity and the presence of vitamin K, chokeberry helps normalize blood clotting, which is important in the treatment of a number of diseases.

Application. In recent years, the fruits of chokeberry have begun to be used for treatment (in the form of extract and infusion); they are prescribed for hypertension and iodine deficiency. Chokeberry juice is used in the initial stage of hypertension, for bleeding of various origins, for atherosclerosis, and anacid gastritis. The fruits of chokeberry are taken for hypertension, hepatitis, allergies, and poisoning.

Drugs. Chokeberry juice. Fresh natural chokeberry juice is obtained from the pulp by pressing the fruit. It has a burgundy color and a sour-bitter astringent taste. Juice is prescribed 50 g per dose 3 times a day, half an hour before meals.

A decoction of chokeberry fruits. Pour 1 tablespoon of dried berries into 1.5 cups of boiling water and leave (daily dose). Take the decoction during the day 3 times a day before meals.

4.4 Plants containing starch

Potato (Solanum tuberosum) of the nightshade family (Solanaceae).

Botanical description.An annual herbaceous, bushy plant with underground shoots that form tubers. The stems are faceted with intermittently dissected leaves. The flowers are white, purple, 2-4 cm in diameter, with a wheel-shaped corolla. The inflorescence consists of 2-3 curls. The fruit is a spherical multi-seeded berry. The seeds are yellow, very small. The color of the tubers is different: red, white, purple.

Spreading.The common potato is native to South America. Introduced to Europe in the 16th century. Initially it was cultivated as an ornamental plant, and from the end of the 17th century. - as food. Currently, many varieties of potatoes are cultivated, differing in the economic and nutritional qualities of the tubers.

Preparation and storage.Tubers and flowers serve as medicinal raw materials. Tubers are dug up in the fall, stored in special storage facilities, in piles, pits, trenches at a temperature of +2°C with fluctuations from 1 to 3°C, with an air humidity of 90%.

Chemical composition.Coumarin and paracoumaric acid were found in potato fruits, flavonoids were found in the inflorescences, and phenolic acids were found in the skin of the tubers. Tubers contain proteins and carbohydrates (20-40% starch), pectins, saccharides, fiber, almost all B vitamins, as well as vitamins C, P, K, PP and A, mineral salts (especially potassium and phosphorus), macro- and trace elements, organic acids and sterols. Potato sprouts and leaves contain six different glycoalkaloids instead of just solanine, as previously thought. Solanine is a crystalline substance with a bitter taste, poorly soluble in water, but soluble in alcohols.

Pharmacological properties.In recent decades, chemists and doctors have been paying increasing attention to potatoes due to the fact that in various organs of the plant, especially in the skin of tubers, flowers, leaves and stems of the tops, a high content of several glucoalkaloids has been revealed, the main of which are solanine and chaconine.

In large doses, these substances, which are similar in chemical structure to the cardiac glycosides of lily of the valley and foxglove, cause severe poisoning even in large animals, manifested in stupor, the appearance of an unsteady gait, dilated pupils, damage to the gastrointestinal tract, impaired breathing, cardiac activity and general circulation. . However, in moderate doses prescribed by a doctor, solanine is used as a remedy. It causes a persistent and long-term decrease in blood pressure, increases the amplitude, makes the heart rate slower, has a pronounced anti-inflammatory, analgesic and antiallergic effect, and has a positive effect on the course and outcome of burn shock and a number of other diseases.

Application. In medicine, fresh potato juice (especially pink) is used as an anti-acid agent for gastritis with increased secretory activity, peptic ulcers and constipation. Take 100-150 ml 20 minutes before meals. The juice moderately stimulates the cardiovascular system. They are used to rinse the mouth and pharynx during inflammatory processes. Grated potato gruel is used to treat burns, panaritiums and non-healing wounds. This not only reduces pain and inflammation, but also improves the processes of cleansing and healing of wounds. Boiled potatoes are used for inhalation and warm compresses are made.

In folk medicine, a decoction of flowers is used to lower blood pressure and stimulate respiration, which is due to the presence of solanine in them.

4.5 Plants containing inulin

Inulin is a natural polysaccharide obtained from the tubers and roots of some plants. Jerusalem artichoke contains the most inulin; there is a lot of it in chicory, garlic, dandelions and in the now fashionable echinacea.

Common chicory (Cichorium intubus) of the Compositae family/

Botanical description. A perennial herbaceous plant with a well-developed tap root, often branched, and an erect, rough, ribbed stem with protruding branches. The basal leaves, notched-pinnate, with a colored main vein, are collected in a rosette. Stem leaves are lanceolate, sharply toothed, stem-embracing. The flower baskets are beautiful, blue, and consist of reed flowers. The fruit is a three-pentagonal achene with a short membranous crown. Chicory blooms from late June to September.

Spreading.Widely distributed in the middle zone and in the south of the European part of the CIS, in the Caucasus and Central Asia, it grows in wastelands, ditches, along roads, near crops as a weed.

Preparation and storage. Chicory roots are harvested in the fall - September, October. Inflorescences - when the plant is flowering.

Chemical composition. The roots contain protein substances, alkaloids, the polysaccharide inulin, the glycoside intibin, sucrose, pentosans, B vitamins, bitterness, pectin, and resins. The flowers are the glycoside chicoryin, the leaves are inulin, the milky juice is bitter.

Pharmacological properties.According to experimental data, an infusion of wild chicory flowers has a calming effect, tones the heart, and has choleretic activity. Chicory enhances urination and bile formation, the functioning of the digestive glands, regulates metabolism, and has antimicrobial, anti-inflammatory and astringent properties. In folk medicine it is used in the form of an aqueous infusion and liquid extract for diabetes mellitus.

Application . Chicory is one of the most used sources of inulin. Even the ancient Egyptians used chicory for food. Chicory has gained the greatest recognition in the treatment of diseases of the gastrointestinal tract and liver. The plant is used as a stomachic, choleretic, laxative and is used to treat diseases of the liver, spleen, kidneys, and skin diseases. Decoctions of roots and inflorescences have a bactericidal and astringent effect.

In folk medicine, chicory has long been used to treat diseases of the stomach, intestines, liver, inflammation of the bladder and difficulty urinating, anemia, spleen tumors, hemoptysis, general weakness, as a blood purifier for skin diseases and a sedative for hysteria. A decoction of the seeds was used as an antipyretic, diaphoretic and analgesic. Infusion of flowers - for increased excitability and pain in the heart. Chicory juice is recommended for anemia, general weakness, and malaria.

Baths made from a decoction of the herb are considered effective for scrofula, diathesis, various joint lesions, and poultices made from the herb are considered effective for abscesses. The ash of the grass, mixed with sour cream, was rubbed into areas of the skin affected by eczema.

Drugs. An infusion of the whole chicory plant. Brew 1 liter of boiling water for 40 g of the plant, leave in a warm place for 3 hours, strain. Drink 0.5 cups 3 times a day to remove excess bile for jaundice, for cirrhosis of the liver, for cleansing the liver and spleen, for tumors of the spleen, clogging of the stomach, pain in the gastrointestinal tract. For stomach poisoning, take 1 glass daily for 3-4 days before breakfast and in the evening.

Chicory herb decoction. Brew 1 cup boiling water 1 tbsp. l. chopped dry or fresh herbs, heat over low heat for 10 minutes, leave for 15 minutes, strain. Drink as tea for diarrhea. Externally, the decoction is used in the form of lotions, washes, baths for the treatment of skin rashes, acne, boils, purulent wounds, pustular skin diseases, eczema, and diathesis in children. Chicory root decoction. Brew 1 cup boiling water 1 tbsp. l. root, heat over low heat for 20 minutes, strain. Drink 1 tbsp. l.5-6 times a day or without dosage as tea.

Conclusion:

Currently, interest in polysaccharides has increased significantly. If previously polysaccharides were mainly used as excipients in the production of various dosage forms, in recent years they have been increasingly considered as biologically active substances. In drug technology, polysaccharides of natural and synthetic origin are used primarily as forming agents, thickeners and stabilizers in ointments and liniments.

Medicinal plants and phytoextracts containing polysaccharides are used as medicinal and prophylactic agents. The use of medicinal herbs in traditional medicine is now especially relevant. Plants have many advantages over chemical medications. The main advantages of their use are the absence of side effects and a complex effect on the body. The problem of human health is considered the most pressing problem of modern medicine, therefore herbal medicines play a significant role in protecting, as well as improving and strengthening the health of millions of people.

Currently, preparations based on polysaccharides obtained from higher (pectins) and lower plants (alginates, carrageenans), secondary raw materials of animal origin (chitosan), mushrooms (christening), etc. are widely used in medicine. Polysaccharides have a wide variety of effects on the body person. In recent years, many laboratories around the world have begun to isolate very valuable polysaccharides from various plants that have antidote, wound-healing, immunostimulating, restorative, antimicrobial, and antitumor properties. Scientists from around the world work tirelessly in this direction, revealing the deeply hidden secrets of the plant world.

Bibliography:

1. Vinogradov T.A., Gazhev B.N. Practical herbal medicine. - M.: Eksmo-Press, 2001.

2. Voys R.F., Fintelmann F. Herbal medicine / trans. with him. - M., 2004.

3. Georgievsky V.P., Komisarenko N.F., Dmitruk S.E. Biologically active substances of medicinal plants. - Novosibirsk, 1990.

4. Action of polysaccharides - http://www.ilonacat.ru/zbk454. shtml

5. Kurkin V.A. Pharmacognosy. - Samara: Ofort LLC, Samara State Medical University, 2004.

6. Ovodov Yu.S. Polysaccharides of flowering plants: structure and physiological activity // Bioorganic chemistry. 1998. T.24, No. 7. P.483-501.

7. Pavlov M. Encyclopedia of medicinal plants. - M., 1998.

8. Pronchenko G.E. Medicinal plant raw materials. - M., 2002.

Other similar works that may interest you.vshm>

There are four main classes of complex bioorganic substances: proteins, fats, nucleic acids and carbohydrates. Polysaccharides belong to the last group. Despite the “sweet” name, most of them perform non-culinary functions.

What is a polysaccharide?

The substances of the group are also called glycans. A polysaccharide is a complex polymer molecule. It is composed of individual monomers - monosaccharide residues, which are united through a glycosidic bond. Simply put, a polysaccharide is a molecule built from the combined residues of more than the number of monomers in a polysaccharide can vary from several tens to a hundred or more. The structure of polysaccharides can be either linear or branched.

Physical properties

Most polysaccharides are insoluble or poorly soluble in water. Most often they are colorless or yellowish. For the most part, polysaccharides are odorless and tasteless, but sometimes they can be sweetish.

Basic chemical properties

Among the special chemical properties of polysaccharides are hydrolysis and the formation of derivatives.

• Hydrolysis is a process that occurs when a carbohydrate reacts with water using enzymes or catalysts such as acids. During this reaction, the polysaccharide breaks down into monosaccharides. Thus, we can say that hydrolysis is the reverse process of polymerization.

Starch glycolysis can be expressed by the following equation:

• (C 6 H 10 O 5) n + n H 2 O = n C 6 H 12 O 6

Thus, when starch reacts with water under the influence of catalysts, we obtain glucose. The number of its molecules will be equal to the number of monomers that formed the starch molecule.

• The formation of derivatives can occur during reactions of polysaccharides with acids. In this case, carbohydrates add acid residues to themselves, resulting in the formation of sulfates, acetates, phosphates, etc. In addition, methanol residues can be added, which leads to the formation

Biological role

Polysaccharides in the cell and body can perform the following functions:

• protective;
• structural;
• storing;
• energy.

The protective function lies primarily in the fact that the cell walls of living organisms consist of polysaccharides. Thus, plants consist of cellulose, fungi - of chitin, bacteria - of murein.

In addition, the protective function of polysaccharides in the human body is expressed in the fact that the glands secrete secrets enriched with these carbohydrates, which protect the walls of organs such as the stomach, intestines, esophagus, bronchi, etc. from mechanical damage and the penetration of pathogenic bacteria.

The structural function of polysaccharides in the cell is that they are part of the plasma membrane. They are also components of organelle membranes.

The next function is that the main reserve substances of organisms are polysaccharides. For animals and fungi, this is glycogen. In plants, the reserve polysaccharide is starch.

The latter function is expressed in the fact that the polysaccharide is an important source of energy for the cell. The cell can obtain it from such a carbohydrate by splitting it into monosaccharides and further oxidation to carbon dioxide and water. On average, when breaking down one gram of polysaccharides, the cell receives 17.6 kJ of energy.

Application of polysaccharides

These substances are widely used in industry and medicine. Most of them are obtained in laboratories by polymerizing simple carbohydrates.

The most widely used polysaccharides are starch, cellulose, dextrin, and agar-agar.

Application of polysaccharides in industry

Substance name	Usage	Source
Starch	Finds application in the food industry. Also serves as a raw material for alcohol. Used for the production of glue and plastics. In addition, it is also used in the textile industry	Obtained from potato tubers, as well as from the seeds of corn, rice, wheat and other starch-rich plants
Cellulose	It is used in the pulp and paper and textile industries: cardboard, paper, and viscose are made from it. Cellulose derivatives (nitro-, methyl-, cellulose acetate, etc.) are widely used in the chemical industry. They are also used to produce synthetic fibers and fabrics, artificial leather, paints, varnishes, plastics, explosives and much more.	This substance is extracted from wood, mainly coniferous plants. It is also possible to obtain cellulose from hemp and cotton
Dextrin	Is a food additive E1400. Also used in the manufacture of adhesives	Obtained from starch by heat treatment
Agar-agar	This substance and it are used as stabilizers in the manufacture of food products (for example, ice cream and marmalade), varnishes, paints	Extracted from brown algae, as it is one of the components of their cell membrane

Now you know what polysaccharides are, what they are used for, what their role is in the body, what physical and chemical properties they have.

Polysaccharides. Starch, Cellulose.

On this page we will look at non-sugar-like polysaccharides.

Polysaccharides- the general name for a class of complex high-molecular carbohydrates, the molecules of which consist of tens, hundreds or thousands of monomers - monosaccharides.

The most important representatives of non-sugar-like polysaccharides – starch And cellulose(cellulose).

These carbohydrates are largely differ from mono- And oligosaccharides. They do not have a sweet taste, and most are insoluble in water. For this reason they are called non-sugar-like(in contrast to sugar-like oligosaccharides, which are also polysaccharides).

Oligosaccharides have a significantly smaller molecular size and properties close to monosaccharides.

Non-sugar-like polysaccharides are high-molecular compounds that, under the catalytic influence of acids or enzymes, undergo hydrolysis to form simpler polysaccharides, then disaccharides and, ultimately, many (hundreds and thousands) of molecules monosaccharides.

Chemical structure of polysaccharides.

By chemical nature polysaccharides should be considered as polyglycosides(polyacetals). Each monosaccharide unit is linked by glycosidic bonds to the previous and subsequent units.

In this case, for communication with the subsequent link, it is provided hemiacetal(glycosidic) hydroxyl group, and with the previous one – alcohol hydroxyl group.

At the end of the chain there is a reducing monosaccharide residue. But since the proportion of the terminal residue relative to the entire macromolecule is very small, then polysaccharides exhibit very weak reducing properties.

Glycosidic nature polysaccharides causes their hydrolysis in acidic and high stability in alkaline media.

Polysaccharides have a large molecular weight. They are characterized by a higher level of structural organization of macromolecules, characteristic of high-molecular substances.

Along with primary structure, i.e. a certain sequence of monomeric residues, plays an important role secondary structure, determined by the spatial arrangement of the molecular chain.

Classification of polysaccharides.

Polysaccharides can be classified according to different criteria.

Polysaccharide chains can be:

• branched or
• unbranched(linear).

Also distinguished:

• homopolysaccharides- polysaccharides consisting of residues of one monosaccharide,
• heteropolysaccharides- polysaccharides, consisting of residues of different monosaccharides.

Most studied homopolysaccharides.

They can be divided according to their origin:

• homopolysaccharides of plant origin
- Starch,
- Cellulose,
- Pectin substances, etc.

• homopolysaccharides of animal origin
- Glycogen,
- Chitin, etc.

• homopolysaccharides of bacterial origin
- Hextrans.

Heteropolysaccharides, which include many animal and bacterial polysaccharides, have been less studied, but they play an important biological role.

Heteropolysaccharides in the body they are associated with proteins and form complex supramolecular complexes.

For polysaccharides common name used glycans.

Glycans can be:

• hexosans (consist of hexoses),
• pentosans, (consist of pentoses).

Depending on the nature of the monosaccharide, they are distinguished:

• glucans (based on monosaccharides glucose),
• mannans (based on monosaccharide mannose),
• galactans (based on monosaccharide galactose) and so on.

Starch

Starch (C 6 H 10 O 5)n– white (granular under a microscope) powder, insoluble in cold water. In hot water, starch swells, forming a colloidal solution (starch paste). With iodine solution it gives a blue color (characteristic reaction).

Starch is formed as a result of photosynthesis, in the leaves of plants, and is stored in tubers, roots, and grains.

Chemical structure of starch

Starch is a mixture of two polysaccharides built from glucose(D-glucopyranose): amylose(10-20%) and amylopectin (80-90%).

The disaccharide moiety of amylose is maltose. In amylose, D-glucopyranose residues are linked by alpha(1-4) glycosidic bonds.

According to X-ray diffraction analysis amylose macromolecule is coiled. For each turn of the helix there are 6 monosaccharide units.

Amylopectin unlike amylose, it has branched structure.

In the chain, D-glucopyranose residues are linked by alpha(1-4)-glycosidic bonds, and at branch points by beta(1-6)-glycosidic bonds. Between the branching points there is 20-25 glucoside residues.

Chain amylose includes from 200 to 1000 glucose residues, molecular weight
160,000. Molecular weight amylopectin reaches 1-6 million

Hydrolytic breakdown of starch.

In the digestive tract of humans and animals starch exposed hydrolysis and turns into glucose, which is absorbed by the body.

In the technology of transformation starch into glucose (saccharification process) is carried out by boiling it for several hours with dilute sulfuric acid. Subsequently, the sulfuric acid is removed. The result is a thick sweet mass, the so-called starch syrup, containing, in addition to glucose, a significant amount of other starch hydrolysis products. Molasses is used for the preparation of confectionery products and various technical purposes.

If you need to get pure glucose, then boiling starch take longer. This achieves a higher degree of hydrolysis starch.

When heating dry starch before 200-500 deg. WITH partial decomposition occurs and a mixture less complex than starch polysaccharides called dextrins.

Decomposition starch Dextrins explain the formation of a shiny crust on baked bread. Starch flour converted into dextrins is easier to digest due to its greater solubility.

Glycogen

In animal organisms this polysaccharide is structural and functional analogue of vegetable starch.

Deposited in the form of granules in the cytoplasm in many types of cells (mainly liver and muscles).

Chemical structure of glycogen.

By structure glycogen similar amylopectin(see structural formula above). But the molecules glycogen much more molecules amylopectin and have a more branched structure. Usually between the branch points there is 10-12 glucose units, and sometimes even 6 .

Strong branching promotes execution glycogen energy function, since only in the presence of a large number of terminal residues can rapid elimination of the required number of molecules be ensured glucose.

Molecular mass at glycogen unusually large. Measurements have shown that it is equal 100 million. This size of macromolecules contributes to the function of reserve carbohydrate. Yes, macromolecule glycogen due to its large size, it does not pass through the membrane and remains inside the cell until the need for energy arises.

Functions of glycogen in metabolism.

Glycogen is the main form of storage glucose in animal cells.

Glycogen forms energy reserve, which can be quickly mobilized if necessary to compensate for a sudden lack of glucose.

Glycogen reserve, however, is not as dense in calories per gram as triglyceride stores ( fat). He has rather local value. Only glycogen stored in liver cells (hepatocytes) can be converted into glucose to feed the entire body.

Glycogen hydrolysis in an acidic environment it occurs very easily with a quantitative yield of glucose.

Likewise glycogen in animal organisms, in plants performs the same role as a reserve polysaccharide amylopectin, having a less branched structure. Less branching is due to the fact that metabolic processes occur much more slowly in plants and a rapid influx of energy is not required, as is sometimes necessary for an animal organism (stressful situations, physical or mental tension).

Cellulose (fiber)

– the most common plant polysaccharide. It has great mechanical strength and plays the role of plant support material.

The purest natural cellulose – cotton fiber– contains 85-90% cellulose. IN wood Coniferous cellulose contains about 50% .

Chemical structure of cellulose

Structural unit cellulose is D-glucopyranose, the units of which are linked by beta(1-4)-glycosidic bonds.

Biose fragment cellulose represents cellobiose. The macromolecular chain has no branches, it contains from 2500 before 12,000 glucose residues, which corresponds to molecular weight from 400,000 to 1-2 million.

The beta configuration of the anomeric carbon atom results in the cellulose macromolecule having strictly linear structure. This is facilitated by the formation of hydrogen bonds within the chain, as well as between neighboring chains.

This packaging of chains provides high mechanical strength, fibrousness, insolubility in water and chemical inertness, which makes cellulose excellent material for building plant cell walls.

Cellulose is not broken down by normal gastrointestinal enzymes, but it is necessary for nutrition ballast.

Use of cellulose

Meaning cellulose very large. It is enough to point out that a huge amount of cotton fiber is used to produce cotton fabrics.

From cellulose they obtain paper and cardboard, and through chemical processing a whole range of different products: artificial fiber, plastics, varnishes, ethyl alcohol.

Of great practical importance cellulose ether derivatives: acetates (rayon), xanthogens (viscose fiber, cellophane), nitrates (explosives, colloxylin), etc.

Polysaccharides of the 2nd order (polyoses). Most of the carbohydrates included in the group of 2nd order polysaccharides are substances with high molecular weight that produce colloidal solutions. When studying the chemical nature of high-molecular polysaccharides, it is very difficult to obtain them in their pure form. Distillation of these substances for the purpose of their purification is impossible, and a number of other substances, in particular mineral salts and proteins present in plants, make it difficult to obtain pure preparations of these carbohydrates. When studying the chemical structure of 2nd order polysaccharides, methods of introducing various organic radicals into their molecules, for example, methyl CH3- or acetyl CH3-CO-, played a very important role. Methylation and acetylation, carried out under mild conditions, make it possible to obtain preparations of methyl and acetyl derivatives of high molecular weight polysaccharides of greater purity than the starting substances. At the same time, the introduction of methyl or acetyl radicals into the polysaccharide molecule greatly facilitates the determination of the structure of the monosaccharides included in its composition, as well as the chemical nature of the bonds connecting the residues of the molecules of individual monosaccharides. A very important method for studying high-molecular polysaccharides is their partial acid or enzymatic hydrolysis; Using mild acid hydrolysis, it was shown that cellobiose is the main structural unit of fiber. Using enzymes, it was found that maltose is the main “building block” of starch.

High molecular weight carbohydrates are extremely important in the metabolism of plants and animals, in the nutrition of animals and humans, and in a number of industries. Thus, starch is a reserve carbohydrate in plants, making up most of the substances that make up many important food products: flour, bread, potatoes and cereals. Pectin substances are found in large quantities in fruits, berries, stems (flax) and roots (sugar beets) and play an important role in the industrial processing of all these plant products. Fiber is not absorbed by the human gastrointestinal tract, but it is of great industrial importance. Fiber consists of cotton, paper, and linen fabrics; it is used to make artificial silk (viscose) and explosives.

Polysaccharide: starch

It is not a chemically individual substance. In plants it is found in the form of starch grains, which differ in their properties and chemical composition both in the same plant and especially in different plants.

Starch grains. Starch grains are oval, spherical or irregular in shape. The sizes (diameter) of starch grains range from 0.002 to 0.15 mm. Potatoes have the largest starch grains, and rice and buckwheat have the smallest. The characteristic shape of starch grains makes it possible to easily distinguish them under a microscope, which is used to detect the admixture of one product with another (for example, corn or oat flour with wheat). Starch grains are divided into simple and complex: simple grains are homogeneous formations (starch grains of potato, wheat, rye); complex grains are a combination of smaller particles (starch grains of oats and rice). However, the division of grain crops into crops with simple and complex starch grains is very arbitrary. For example, along with simple starch grains in wheat there are also complex ones and, conversely, among the predominant complex ones in oats there are also simple ones. The density of starch is on average 1.5. When examining starch grains in a polarizing microscope, it is discovered that they are birefringent, i.e., they are a crystalline body. Indeed, X-ray studies have shown that starch grains have a crystalline structure.

Properties of starch. A characteristic property of starch is its ability to turn blue when a solution of iodine is added to an aqueous solution of potassium iodide. Using this reagent, very small amounts of starch can be detected. The appearance of a blue color when iodine is added is apparently explained by the formation of complex and adsorption compounds between iodine and starch. In cold water, starch grains only swell, but do not dissolve. If a suspension of starch grains in water is gradually heated, they will swell more and more and, finally, at a certain temperature, the starch forms a viscous colloidal solution called starch paste. The temperature at which this change in starch occurs is called the gelatinization temperature. Starch consists of 96.1-97.6% polysaccharides, which form glucose during acid hydrolysis. The content of minerals in starch is from 0.2 to 0.7%, they are represented mainly by phosphoric acid. Starch also contains some high-molecular fatty acids and palmitic, stearic, etc., the content of which reaches 0.6%. These fatty acids are adsorbed on the polysaccharide fraction of starch; they can be removed from it by extraction with neutral organic solvents, such as methyl alcohol. Phosphoric acid in some starches - corn, wheat and rice - is an impurity that can be removed by extraction with warm water, alcohol or dioxane, while in others, such as potato, it is bound by an ester bond to the carbohydrate moiety. The presence of such a strong chemical bond of phosphoric acid in potato starch is proven by the fact that its acid or enzymatic hydrolysis produces glucose-6-phosphate. Some researchers attach great importance to the presence of chemically bound phosphoric acid in potato starch, believing that many of the physical and chemical properties of starch depend on it. However, this view currently has no reliable evidence. The carbohydrate part of starch consists of two types of polysaccharides that differ in their physical and chemical properties - amylose and amylopectin. Amylose easily dissolves in warm water and produces solutions with a relatively low viscosity. Amylopectin dissolves in water only when heated under pressure and produces very viscous solutions. The molecular weight of amylose is 3x100,000-1000,000, and for amylopectin it reaches hundreds of millions. Amylose solutions are very unstable, and when standing, crystalline precipitates are released from them. Amylopectin, on the contrary, produces extremely stable solutions.

Amylose is stained blue by iodine solution, and amylopectin is stained blue-violet. It has been established that staining of amylose with iodine is accompanied by the formation of a complex chemical compound. In this case, iodine molecules are located inside the spirally curved amylose chains. Iodine staining of amylopectin appears to result from the formation of both complex and adsorption compounds. The content of amylose and amylopectin in the starch of various plants was determined only in recent years after sufficiently accurate methods were developed. The most important of these methods are the following: 1) extraction of amylose with hot water; 2) precipitation of amylose from solutions using butyl and other alcohols; 3) selective adsorption of amylose on fiber; 4) potentiometric titration with iodine.

Analyzes of various starches carried out using these methods gave the following results: potato starch contains 19-22% amylose and 78-81% amylopectin; wheat - 24% and 76%, respectively; corn - 21-23% and 77-79%, respectively; rice starch - 17 and 83%, respectively. Apple starch consists only of amylose.

It should be noted that the content of amylose and amylopectin in starch can vary depending on the plant variety and what part of the plant it is obtained from. For example, in this sense, starches from round and brain peas, starch from leaves and tubers of potatoes, or starch from grains of different varieties of corn differ. If the amylose content in starch from potato tubers is 22%, then in starch from young potato shoots it is 46%. If the starch from the grain of ordinary corn contains 22% amylose, then the starch of the so-called waxy corn (Zea mays carina) contains no amylose completely, as a result of which the starch from the grains of this plant is colored red-brown with iodine. On the other hand, corn varieties have been developed whose starch contains up to 82% amylose. The ratio of amylose and amylopectin in starch also changes during the ripening of corn grains. When boiled with acids, starch is converted into glucose. With weaker exposure to acids, the so-called “soluble starch” is formed, often used in laboratories. Under the action of the enzyme amylase, which is contained in especially large quantities in sprouted grains, in saliva and in the juice secreted by the pancreas, enzymatic saccharification of starch occurs - it is broken down to ultimately form maltose.

Polysaccharides: dextrins

As an intermediate product during the hydrolysis of starch, polysaccharides of different molecular weights - dextrins - are formed in greater or lesser quantities. At the first stages of hydrolysis, dextrins are obtained, which differ little from starch in molecular size and properties. With iodine they give a blue or violet color. With further hydrolysis, the molecular weight of dextrins decreases, their ability to reduce fehling fluid increases, and from iodine they begin to turn dark brown, then red, and finally stop reacting with iodine. According to their properties, the following types of dextrins are distinguished: 1) amylodextrins, which are stained violet-blue with iodine solution and are white powders, soluble in 25% alcohol, but precipitated by 40% alcohol; the specific rotation of amylodextrins ranges from + 190 to + 196 C; 2) erythrodextrins, stained red-brown with iodine; dissolve in 55% ethyl alcohol, but precipitate at a concentration of 65%; specific rotation of erythrodextrins D = + 194 C; from warm alcoholic solutions they crystallize in the form of spherocrystals; 3) achroodextrins, not stained by iodine, soluble in 70% alcohol, form spherocrystals when hot alcohol solutions are evaporated; specific rotation + 192 C; 4) maltodextrins do not react with iodine and are not precipitated by alcohol, specific rotation is from + 181 to + 183 C.

Polysaccharide: inulin

A high molecular weight carbohydrate, soluble in water, precipitating from aqueous solutions when alcohol is added. When hydrolyzed with acids, it forms fructofuranose and a small amount of glucopyranose. Contained in large quantities in the tubers of earthen pear and dahlia, in the roots of dandelion, kok-sagyz and chicory, in artichokes, in the roots, leaves and stems of the rubber plant guayule (Parthenium argentatum). In these plants, inulin replaces starch. In dahlia and artichoke tubers, inulin makes up more than 50% of the wet weight of the tissue. The biosynthesis and transformation of inulin and inulin-like polyfructosides have been especially well studied using the example of pear and artichoke (D. Edelman, R. Dedoner). Plants containing inulin are used to produce fructose. Since all fructosides, including inulin, are very easily hydrolyzed by acids, fructose is obtained from inulin-containing raw materials by acid hydrolysis. The number of fructose residues connected in the inulin molecule by glycosidic bonds between the l-th and 2-nd carbon atoms is 34. Plants, molds and yeast contain a special enzyme - nulase, which hydrolyzes inulin to form fructose.

Polysaccharides: polyfructosides

Many plants contain various other polysaccharides that yield fructofuranose upon acid hydrolysis. These are, for example, irisin from the rhizomes of iris, asparagosine from the roots of asparagus, polyfructosides from the stems, leaves and rhizomes of many cereals, secalin from rye, etc. In ripening cereal grains of rye, wheat, oats and barley, these polysaccharides are contained in very large quantities. In the early stages of rye grain ripening, they contain up to 30% of the dry matter. As grains mature, these polysaccharides are gradually converted to starch, indicating that fructose is easily converted into glucose in plants. Polyfructosides contained in the leaves, stems and grains of cereals differ in their molecular weights, solubility and other properties. Some of them are l-th order polysaccharides. Thus, beta-levulin, found in the stalks of rye, is a crystalline substance corresponding to the formula C12H22OH, and therefore contains two fructose residues; secalin, isolated from the leaves and stems of rye, has a molecular weight of 663, which corresponds to the content of four fructose residues in its molecule. The colloidal polyfructoside gramine, contained in mature rye grains, contains 10 fructose residues per molecule. Thus, in the rye plant there are transitions from fructosides with a small molecular weight to polyfructosides with a large molecular weight. Similar transitions from low-molecular-weight crystalline polyfructosides to higher-molecular-weight compounds, up to inulin, take place in the pear plant. Thus, polyfructosides form a homologous series of substances in plants with increasing molecular size. The extreme members of this series are beta-levulin difructoside and inulin, the molecule of which contains 34 fructose residues. Polyfructosides, like inulin, usually contain very small amounts of glucopyranose and are very easily hydrolyzed by dilute acids.

Polysaccharide: Glycogen

A polysaccharide found in human and animal body tissues, in fungi and yeast, and in sweet corn grains. Plays an important role in the transformation of carbohydrates in the animal body and in yeast during alcoholic fermentation. When boiled with acids, it forms glucose. Glycogen dissolves in hot water, forming opalescent solutions. From iodine it turns red, brown, and less often purple. The structure of glycogen is similar to amylopectin, although it differs from it in its larger molecular weight. The molecules of both polysaccharides have a branched structure, but glycogen is distinguished by a more “compact” molecule.

Polysaccharide: Callose

Callose. A polysaccharide found in the sieve tubes of plants. It is a glucan, the molecule of which consists of approximately 100 glucose residues connected by beta-1-3 bonds. Apparently, callose plays some important physiological role in plants, since it is easily formed and consumed with the same ease.

Polysaccharide: Lichenin

Likhenin. A polysaccharide found in lichens. Particularly high amounts of lichenin are found in the lichen called “Icelandic moss” (Cetraria islandica), as well as in lichens of the genus Alectoria (Alectoria ochroleuca). These lichens contain up to 45-50% lichenin on a dry matter basis. Lichenin dissolves in hot water and in dilute aqueous solutions of alkalis; when hydrolyzed with acids, it forms 98-99% D-glucose. Apparently, lichenin is a mixture of homologous polymers of different molecular weights. The glucose residues in lichenin are linked in two ways - 73% by glucosidic bonds between the 1st and 4th carbon atoms (as in amylose) and 27% by glucosidic bonds between the 1st and 3rd carbon atoms. The gastrointestinal tract of reindeer, for which lichens are the main food, digests lichenin by 78%. At the same time, the digestive juices of reindeer themselves do not digest lichenin; its digestion is carried out by bacteria in the digestive tract of deer. Lichenin is not absorbed by the human body. Lichenin can be used as a gelling agent in the confectionery industry; Residents of the North use lichens to make berry jelly and jellies.

Polysaccharide: Fiber

(cellulose) is a polysaccharide that makes up the bulk of plant cell walls. Fiber is insoluble in water; it only swells in it. Fiber makes up more than 50% of wood. In cotton fibers it is more than 90%. When boiled with strong sulfuric acid, the fiber is completely converted into glucose. With weaker hydrolysis, cellobiose is obtained from fiber. In the fiber molecule, cellobiose residues are linked by glycosidic bonds in the form of a long chain. The molecular mass of fiber has not been precisely established. It is believed that fiber is not an individual substance, but is a mixture of homologous substances. The molecular weights of fiber obtained from various sources vary greatly: cotton - 330,000 (2020 glycosidic residues in the chain); ramie - 430,000 (2660 remains), spruce wood - 220,000 (1360 remains). Using X-ray diffraction analysis, it was found that fiber molecules have a thread-like shape. These thread-like molecules are connected into bundles - micelles. Each micelle consists of approximately 40-60 fiber molecules. The combination of individual fiber molecules into micelles occurs due to hydrogen bonds, which are carried out both due to the hydrogen atoms of the hydroxyl groups of the fiber and due to water molecules adsorbed by the fiber. In plant cell walls, fiber micelles are hydrogen bonded to various heteropolysaccharides. For example, in white maple they are xyloglucan interconnected by glycosidic bonds, consisting of glucose, xylose, galactose and fucose residues; arabinogalactan, built from arabinose and galactose residues; rhamnogalacturonan, formed by galacturonic acid and rhamnose residues. In addition, there is evidence that a special glycoprotein, extensin, rich in hydroxyproline, also takes part in the construction of the plant cell wall, especially in the early stages of its formation. When cell walls become lignified, lignin also accumulates in them. Fiber is not digested in the human gastrointestinal tract. It is digested only by ruminants, whose stomachs contain special bacteria that hydrolyze fiber using the cellulase enzyme they secrete. Hemicelluloses (semi-fiber). This name combines a large group of high molecular weight polysaccharides that are insoluble in water, but soluble in alkaline solutions. Hemicelluloses are found in significant quantities in lignified parts of plants: straw, seeds, nuts, wood, corn cobs. A large amount of hemicelluloses are found in bran. Hemicelluloses are hydrolyzed by acids more easily than fiber. At the same time, they form mannose, galactose, arabinose or xylose and therefore are named accordingly - mannans, galactans and pentosans (araban or xylan).

Mannan, containing 200 to 400 mannose residues per molecule, found in yeast. A certain amount of mannans is contained in the wood of coniferous trees (from 2 to 7%). Water-soluble mannan and galactan are secreted by the mycelium of molds belonging to the genus Penicillium. Galactans widely distributed in plants and are part of the cell walls of straw, wood and many seeds. A typical representative of this group of polysaccharides is galactan, found in lupine seeds. Xylans are contained in significant quantities in straw (up to 28%), wood (in oak up to 25%) and plant fibers. Typically, xylan contained in any plant object is a mixture of various polysaccharides with similar molecular weights (usually from 50 to 200 xylose residues), but differing in the nature of the sugar residue in the “branches” of the molecule.

Polysaccharides: mucus and gum

Slime and gummi. This group of colloidal polysaccharides includes water-soluble carbohydrates that form extremely viscous and sticky solutions. Typical representatives of this group are gums, secreted in the form of influxes by cherry, plum or almond trees in places where branches and trunks are damaged. Mucus is found in large quantities in flaxseeds and rye grains. Their presence explains the high viscosity of a decoction of flaxseeds or water mash of rye flour used in medicine. Cherry glue polysaccharides consist of galactose, mannose, arabinose, D-glucuronic acid and a small amount of xylose residues. Almost 90% of rye grain mucilage consists of pentosans. They swell strongly in water and produce very viscous solutions. Their viscosity is significantly higher than the viscosity of solutions of gelatin, starch paste or protein. Acid hydrolysis of rye grain mucilage produces xylose, arabinose and a small amount of galactose.

Polysaccharides: Pectins

High-molecular compounds of carbohydrate nature, contained in large quantities in berries, fruits, tubers and plant stems. In plants, pectins are present in the form of insoluble protopectin, which is a compound of methoxylated polygalacturonic acid with galactan and araban of the cell wall. Protopectin becomes soluble pectin only after treatment with dilute acids or under the action of a special enzyme, protopectinase. From an aqueous solution, soluble pectin is precipitated with alcohol or 50% acetone. A characteristic and important property of pectin is its ability to form jellies in the presence of acid and sugar. This property is widely used in the confectionery industry in the production of jelly, jam, marmalade, marshmallows and fruit caramel fillings. The formation of pectin jelly occurs in the presence of 65-70% sugar (sucrose or hexose); this concentration approximately corresponds to a saturated sucrose solution. The resulting jelly contains from 0.2 to 1.5% pectin. The best formation of pectin jellies occurs at a pH of 3.1-3.5. Pectins of different origins differ in their ability to gel, in the content of ash and methoxyl groups CH3O-.

When soluble pectin is exposed to dilute alkalis or the enzyme pectase, methoxy groups are easily split off - methyl alcohol and free pectic acid, which is polygalacturonic acid, are formed. Pectic acid easily produces salts - pectates. In the form of calcium pectate, it easily precipitates from solution; this is used for the quantitative determination of pectin substances. Pectic acid in the presence of sugar is not able to form jellies like soluble pectin. Therefore, during the industrial production of pectin, they try, if possible, to avoid its alkaline or enzymatic hydrolysis, which causes a decrease in the gelling ability of pectin. Pectins play an important role in the ripening, storage and industrial processing of various fruits and vegetables. During fruit development, protopectin is deposited in cell walls and can accumulate in fruits in significant quantities (for example, in pears, apples and citrus fruits). Fruit ripening is characterized by the conversion of protopectin into soluble pectin. Thus, in apples, the pectin content reaches a maximum around the period of fruit harvesting. With subsequent storage of fruits at temperatures close to 1 C, the protopectin content gradually decreases and soluble pectin accumulates. Pectin content in fruits and vegetables, % Apples - 0.82-1.29, Apricots - 1.03, Plums - 0.96-1.14, Blackcurrants - 1.52, Cranberries - 0.5-1.30 , Carrots - 2.5, Sugar beets - 2.5. Pectins also play an important role in the processing of plant fibers, such as flax. The process of flax retting is based on the fact that under the influence of special microorganisms that secrete enzymes that hydrolyze pectin substances, maceration of flax stems occurs and the fibers are separated from each other.

Polysaccharides: Agar-agar

Agar-agar. A high molecular weight polysaccharide found in some seaweeds belonging to the genera Gelidium, Gracilaria, Pterocladia and Ahnfeltia. In the USSR, agar-agar was extracted from the purple ahnfeltia algae, which grows in the White, Barents and Baltic seas, as well as in the reservoirs of the Far East. Agar-agar is insoluble in cold water, but dissolves in it when heated. When cooled, its aqueous solutions solidify into jelly. Agar-agar is used in bacteriology for the preparation of solid nutrient media, in the confectionery industry for the production of various jellies, marshmallows, marmalade, and jams. Agar-agar is a mixture of at least two polysaccharides - agarose and agaropectin. Agarose most likely consists of D-galactose and 3,6L-galactose residues linked by alpha-1,3- and beta-1,4-glycosidic bonds. Much less is known about the structure of agaropectin, which appears to consist of chains formed by D-galactopyranose residues, some of which are linked by ester bonds to sulfuric acid residues. The scarlet phyllophora algae, which grows in large quantities in the Black Sea, contains agaroid and agaroidin - gelling substances of a carbohydrate nature, differing from agar in their chemical nature. The jelly-like substance carrageenine is obtained from the scarlet seaweed Chondrus. The chemical structure of agaroid, agaroidin and carrageenine is not well understood. Carrageenine is a polysaccharide consisting mainly of galactopyranose residues connected by alpha-1,3- and beta-1,4-glycosidic bonds; Most of the galactopyranose residues at the fourth carbon atom are linked by an ester bond to a sulfuric acid residue. Carrageenine appears to have a branched structure and consists of components with different molecular weights - from 358,000 to 700,000.

Alginic acid. This polysaccharide is a constituent of the cell walls of many algae belonging to the genera Macrocystis, Laminaria and Fucus. Alginic acid appears to be an analogue of pectic acid, but consists of D-mannuronic and L-guluronic acid residues linked by beta-glycosidic bonds located between the lth carbon atom of one mannuronic or guluronic acid residue and the 4th carbon atom of the other . Alginic acid is present in algae in the form of salts and is contained in them in an amount of 30% of the dry mass of algae. Alginic acid and its salts, mainly sodium, are widely used as emulsifying agents; They are especially widely used as stabilizers in the production of ice cream and various technical emulsions.

Bacterial polysaccharides

Bacterial polysaccharides. Bacteria produce significant amounts of polysaccharides, which are contained in the cytoplasm or deposited as reserves of nutrients, or are located on the surface of the cell, forming a mucous protective layer (capsule). Often the capsules dissolve in the liquid in which bacteria grow. In pathogenic bacteria, the capsule is, first of all, a means of protecting the cell from phagocytes. In soil bacteria, like some nitrogen-fixing bacteria, capsule-forming substances appear to provide some protection to the cells from soil protozoa. Typical representatives of bacterial polysaccharides are dextrans, a group of polyglucosides formed from cane sugar by various Leuconostoc species. Some non-pathogenic microorganisms, when developing on sucrose solutions, form polyfructosides called levans. Significant quantities of levans are produced, for example, by certain types of streptococcus and Bacillus subtilis, which causes the so-called stringy bread disease. Many levans are produced by plant pathogenic bacteria such as Bacillus pruni, but the possible role of these polysaccharides in disease development is unclear. Mucous polysaccharides like levans and dextrans are also produced by soil bacteria, and, apparently, these carbohydrates play a certain role in the aggregation of soil and the preservation of moisture in it. Capsular polysaccharides of nitrogen-fixing bacteria, for example, rhizobium sp, have a unique structure: These polysaccharides, along with glucopyranose residues, contain glucuronic acid residues. Some specific bacterial polysaccharides play an extremely important role in the immunity of animals and humans.