primary metabolites. Primary and secondary metabolites of microorganisms. Physiological basis of the advantages of immobilized plant cells over traditional methods of cultivation

Secondary metabolites are the most important physiologically active compounds in the plant world. Their number, studied by science, is increasing every year. At the moment, about 15% of all plant species have been studied for the presence of these substances. They also have high biological activity in relation to the body of animals and humans, which determines their potential as pharmaceuticals.

A distinctive feature of all living organisms is that they undergo metabolism - metabolism. It is a set of chemical reactions that produce primary and secondary metabolites.

The difference between them is that the former are characteristic of all creatures (the synthesis of proteins, aminocarboxylic and nucleic acids, carbohydrates, purines, vitamins), while the latter are characteristic of certain types of organisms and do not participate in the growth and reproduction process. However, they also perform certain functions.

In the animal kingdom, secondary compounds are rarely produced; more often they enter the body along with plant foods. These substances are synthesized mainly in plants, fungi, sponges and unicellular bacteria.

Signs and features

In biochemistry, the following main signs of secondary plant metabolites are distinguished:

high biological activity;

small molecular weight (2-3 kDa);

production from a small amount of starting materials (5-6 amino acids for 7 alkaloids);

synthesis is inherent in individual plant species;

formation at later stages of development of a living organism.

Any of these features are optional. Thus, secondary phenolic metabolites are produced in all plant species, and natural rubber has a high molecular weight. The production of secondary metabolites in plants occurs only on the basis of proteins, lipids and carbohydrates under the influence of various enzymes. Such compounds do not have their own way for synthesis.

They also have the following features:

presence in different parts of the plant;

uneven distribution in tissues;

localization in certain compartments of the cell to neutralize the biological activity of secondary metabolites;

the presence of a basic structure (most often hydroxyl, methyl, methoxyl groups act in its role), on the basis of which other variants of compounds are formed;

different types of structure changes;

the ability to switch to an inactive, “reserve” form;

lack of direct participation in metabolism.

Secondary metabolism is often considered as the ability of a living organism to interact with its own enzymes and genetic material. The main process resulting in the formation of secondary compounds is dissimilation (decomposition of the products of primary synthesis). In this case, a certain amount of energy is released, which is involved in the production of secondary compounds.

Functions

Initially, these substances were considered unnecessary waste products of living organisms. It is now established that they play a certain role in metabolic processes:

MINISTRY OF AGRICULTURE OF THE RUSSIAN FEDERATION

"VORONEZH STATE AGRARIAN UNIVERSITY

NAMED AFTER EMPEROR PETER I"

Department of Botany, Plant Protection, Biochemistry and Microbiology

Course work

in plant biochemistry

Topic: Secondary Metabolites

Completed: student TT-2-1b

Kalinina Yana Gennadievna

Checked by: Associate Professor

Maraeva Olga Borisovna

VORONEZH 2013

Introduction

Secondary metabolites - compounds, often of complex composition, which are not the main intermediate compounds of cell metabolism, are formed in its dead-end branches. Metabolites of secondary plants are, for example, alkaloids. Microorganisms form secondary metabolites, as a rule, during the period of slowdown or cessation of active growth and reproduction of crops. Microorganisms form some pigments, antibiotics, and vitamins as secondary metabolites. Of great importance is the synthesis of secondary metabolites by microorganisms in the formation of soil humus.

Whatever way photosynthesis is carried out, in the end it ends with the accumulation of energy-rich reserve substances that form the basis for maintaining the life of the cell and, ultimately, the entire multicellular organism. These substances are products of primary metabolism. In addition to their main function, primary metabolites are the basis for the biosynthesis of compounds that are commonly called products of secondary metabolism. The latter, often conditionally called "secondary metabolites", are wholly "owed" their existence in nature to the products formed as a result of photosynthesis. It should be noted that the synthesis of secondary metabolites is carried out due to the energy released in mitochondria during cellular respiration.

1. Literature review

1.1 Signs of secondary metabolites

It is far from always possible to distinguish secondary metabolites from primary ones by the chemical structure of a molecule. On fig. 1 shows some examples of primary and secondary metabolites.

Rice. 1. Structures of campesterol (primary metabolite), ecdysone and protopanaxatriol (secondary metabolites)

Phytosterols (sitosterol, campesterol, stigmasterol) are essential components of plant cell membranes and, therefore, are typical primary compounds. Ecdysteroids (insect molting hormones) are secondary metabolites present only in some plant species. These substances are believed to be involved in protecting plants from insects. Protopanaxatriol is an aglycone of ginsenosides, secondary metabolites of ginseng, which are present only in the Rapax genus and are largely responsible for its biological activity. At the same time, the molecular structures of these compounds are similar and differ only in the number and arrangement of methyl and hydroxyl groups. The structures of protein amino acids (primary metabolites) and non-protein amino acids (typical secondary metabolites) often differ only in the presence or absence of a methyl, hydroxyl, or other functional group.

Based on the analysis of the literature, four signs of secondary metabolites can be formulated:

) not present in all plants;

) presence of biological activity;

) relatively low molecular weight;

) a small set of starting compounds for their synthesis.

These are precisely the signs of secondary metabolites, since each of them, in general, is not required. A number of secondary metabolites are found in almost all plants (for example, many phenylpropanoids); quite a lot of secondary metabolites without pronounced biological activity (although it is possible that it was simply not found); high-molecular secondary metabolites are known (for example, rubber and gutta-percha). However, the combination of these features clearly outlines the range of secondary plant metabolites.

The most justified classification of a compound as a primary or secondary metabolite is possible only after its role in the vital activity of the plant has been clarified; based on its functional significance. The functional definition of secondary metabolism in the first approximation can be given as the metabolism of compounds that are important at the cellular level.

1.2 Principles for the classification of secondary metabolites

The principles of classification of secondary metabolites, as well as the names of individual compounds, changed as they were studied. Now you can find elements of at least four classification options.

Empirical (trivial) classification. The most "ancient" principle of classification, based on certain properties of secondary metabolites. For example, alkaloids are compounds that have alkaline properties; saponins - substances that form foam when shaken; bitterness - compounds with a bitter taste; essential oils are fragrant volatile secondary metabolites. This principle of classification has many shortcomings, but its elements are still found due to tradition and long-term use.

Secondary metabolites received (and receive) their names, as a rule, also empirically. Most often, the names come from the plant from which the compound was first isolated. For example, alkaloids papaverine (poppy), berberine (barberry), cocaine (coca bush). Quite often, the names are associated with mythology, history, personalities, etc. For example, the alkaloid morphine got its name in honor of the god of sleep. This way of classifying and naming compounds often leads to misunderstandings. For example, biologically active triterpene glycosides of ginseng almost simultaneously began to be studied in Japan and Russia. Japanese researchers suggested calling them ginsenosides - according to the species name of ginseng, while Russian researchers - panaxosides, i.e. by generic name. Later, when it became clear that the same compounds were called differently, "correspondence tables" of ginsenosides and panaxosides had to be published.

Chemical classification. This version of the classification is based on the signs of the chemical structure of secondary metabolites and is currently the most developed and widespread. However, this classification is not without drawbacks. For example, according to this classification, alkaloids are compounds that have a nitrogen atom in the heterocycle. According to this feature, potato or tomato glycoalkaloids are typical alkaloids, however, according to the method of synthesis, structure, and a number of properties, these compounds are isoprenoids.

Biochemical classification. This classification is based on the methods of biosynthesis of secondary metabolites. For example, according to this classification, the glycoalkaloids mentioned above belong to triterpene pseudoalkaloids, since they are synthesized, like steroid glycosides, along the isoprenoid pathway. This seems to be the most objective classification option. However, since the biochemistry of secondary metabolism has not yet been sufficiently developed, such a classification is in its infancy.

Functional classification. Based on the functions of secondary metabolites in an intact plant. This option is fundamentally different from the previous ones and should exist in parallel with them. According to the functional classification, chemically different structures can fall into one group of compounds. For example, phytoalexins (secondary metabolites that have protective functions and are synthesized in response to a pathogen attack) are represented in various forms by phenolic compounds, isoprenoids, polyacetylenes, etc. The development of a functional classification of secondary metabolites is just beginning, but it is of fundamental importance for plant physiology.

The presence of different options for the classification of secondary metabolites leads to certain difficulties. In particular, when using different features used in chemical classification, it is possible to "overlap" groups of secondary metabolites. For example, in “pharmacognosy”, glycosides (compounds whose molecule consists of aglycone and a carbohydrate fragment) are isolated as active ingredients of many medicinal plants into a separate group. At the same time, according to the aglycone structure, these glycosides can be assigned to phenolic compounds, isoprenoids, or other groups of secondary metabolites. Even more problems arise when the compound contains a number of features characteristic of different groups of secondary metabolites (for example, prenylated phenolic compounds). In some cases, emerging problems can be removed by adjusting the chemical classification of the biochemical one.

1.3 Major groups of secondary metabolites

Currently, more than a dozen groups (classes) of secondary metabolites are known. At the same time, some groups have several thousand individual compounds, while others - only a few. Groups in the plant world are also unevenly distributed. For example, isoprenoids and phenolic compounds are present in all plant species, while some groups (for example, thiophenes or acetogenins) are characteristic only of single species.

The three largest groups of secondary metabolites are well known - alkaloids, isoprenoids (terpenoids) and phenolic compounds. Each of these groups consists of several thousand compounds and is subdivided into numerous subgroups. About a dozen less numerous groups of secondary metabolites are also known: plant amines, non-protein amino acids, cyanogenic glycosides, glucosinolates, polyacetylenes, betalains, alkylamides, thiophenes, etc. The number of compounds included in these groups varies from units to several hundreds.

Secondary metabolites in the plant are almost never present in a "pure form", they, as a rule, are part of complex mixtures. Such mixtures, depending on their composition and presence in the plant, often have their own, historically established names.

Essential oils, as a rule, are a mixture of easily evaporating isoprenoids (mono- and sesquiterpenes).

Resins are mainly represented by diterpenes.

Gums consist mainly of polysaccharides, but they often include alkaloids, phenolic compounds.

Mucus is a mixture of water-soluble oligo- and polysaccharides, sugars, as well as small amounts of phenolic compounds, alkaloids or isoprenoids.

1.4 Structure patterns of secondary metabolites

When analyzing the structures of secondary metabolites, it seems that their great diversity occurs according to a certain pattern. As a rule, there is a certain "basic" structure, on the basis of which numerous options are formed. In this case, there are several ways in which such options can arise.

Modifications of the basic structure: usually this is either the addition or replacement of functional groups, a change in the degree of oxidation of the molecule; hydroxyl, methyl or methoxy groups are often used as functional groups.

Formation of conjugates: attachment to the basic structure of "unified blocks"; most often various sugars (mono- or oligosaccharides), organic acids or some groups of secondary metabolites.

Condensation: The combination of several identical or different basic structures, such as the formation of prenylated phenolic compounds or dimeric indole alkaloids.

For different groups of secondary metabolites, specific changes in the structure are characteristic. For example, alkaloids are characterized by methoxylation, but not glycosylation; for isopreoids, on the contrary, glycosylation is typical, but not methoxylation; in phenolic compounds, both types of these modifications are observed.

Certain modifications of molecules seem to have significant functional significance. Many of them (in particular, glycosylation) significantly change the biological activity of the molecule. Very often, glycosylation is a universal way to transfer the active (functional) form of a secondary metabolite into an inactive (reserve) one. For this reason, it seems inappropriate to isolate all glycosides into a separate group of secondary metabolites.

1.5. Phytochemistry of Secondary Metabolism

Alkaloids. The name of this group of substances comes from the Arabic alcali - alkali and the Greek eidos - similar. Currently, about 10,000 individual alkaloids are known.

In the case of alkaloids, the empirical and chemical classification coincided rather successfully. According to the chemical classification, alkaloids are compounds containing one or more nitrogen atoms in the molecule, which gives them alkaline properties. According to their chemical structure, alkaloids are usually divided into two subgroups: protoalkaloids, which contain nitrogen not in the heterocycle, and true alkaloids, which contain nitrogen in the heterocycle. The distribution of alkaloids into subgroups was corrected by the biochemical classification. Glycoalkaloids, as well as a number of other alkaloids (for example, aconite alkaloids), are actually isoprenoids by the type of synthesis and by structure. Therefore, it was decided to separate them into a special group - isoprenoid pseudoalkaloids.

The most widely distributed alkaloids among angiosperms. The families of poppy, nightshade, legume, kutra, madder, ranunculaceae are especially rich in them. In mosses, ferns, gymnosperms, alkaloids are relatively rare.

Different organs and tissues of a plant may contain different alkaloids. Usually their concentration is small and amounts to tenths and hundredths of a percent. With an alkaloid content of about 1 - 3%, the plant is considered rich in alkaloids (alkaloid-bearing). Only a few plants, such as cultivated forms of cinchona, can accumulate up to 15 - 20% alkaloids. Protoalkaloids are quite common in plants of different families, but, as a rule, do not accumulate in significant quantities.

Alkaloids accumulate, as a rule, in vacuoles, and practically do not enter the periplasmic space. Perhaps this is a consequence of the “careful attitude” of the plant to nitrogen-containing compounds. The transport of alkaloids into the vacuole takes place with the participation of specific carriers (apparently, ABC transporters). In any case, only "own" alkaloids effectively enter isolated vacuoles, i.e. characteristic of this plant. In vacuoles, alkaloids are usually found in the form of salts. The synthesis of alkaloids takes place mainly in plastids or in the cytosol.

Rice. 2. Structures of some alkaloids

Isoprenoids are an extensive group of compounds having the general formula (C5H8)n. C5H8 is a unit of isoprene, so isoprenoids are compounds "made up" of several isoprene units. Their biosynthesis really goes by the combination of five-carbon fragments, therefore the name of this group of substances coincides with their biochemical classification.

The classification of isoprenoids is based on the number of isoprene units that make up the molecule. Compounds based on only one isoprene unit have been discovered in plants only relatively recently. Therefore, it has historically developed that compounds containing two isoprene units and, therefore, having the general formula (C5H8)2, were called monoterpenes, i.e. C10H16. Isoprenoids containing three isoprene units were called sesquiterpenes, the general formula is C15H24. Accordingly, diterpenes are built from four, triterpenes from six and tetraterpenes from eight five-carbon fragments. When compounds consisting of one and five isoprene units were discovered, they had to be called hemiterpenes and sesterterpenes, respectively. Polyterpenoids rubber and guta contain from 100 to 5000 units of isoprene.

Mono- and sesquiterpenoids are, as a rule, volatile liquids, often with a variety of odors. More than 3000 of these compounds are known. Their classification is based on the presence or absence of a ring structure in the molecule, the type of ring, and the presence and number of double bonds in the molecule. Mono- and sesquiterpenes can be aliphatic (a hydrocarbon with an open chain of atoms), cyclic with a different number of cycles (from one to three), and also contain various functional groups (hydroxy, carboxy, keto groups). They form the basis of essential oils. Mono- and sesquiterpenoids are often bactericidal.

Diterpenoids also have several thousand structures. They are the main components of resins in gymnosperms (spruce, pine, fir, cedar). Resin diterpenoids often have bactericidal properties.

Triterpenoids are represented by several groups of compounds. First of all, these are compounds of primary metabolism - phytosterols, however, most triterpenoids are typical secondary metabolites. Triterpenoids have a wide spectrum of biological activity. These include cardiac, steroid, triterpene glycosides, ecdysteroids.

Tetraterpenoids are present in plants mainly as carotenoids, some of them are involved in the main metabolism (photosynthesis), but the majority (about 500) are typically secondary metabolites.

Isoprenoid secondary metabolites, unlike alkaloids, are usually excreted from the cell after synthesis. In addition to the cell wall, they can sometimes accumulate in vacuoles. Synthesis of isoprenoids can take place in two compartments - in plastids or in the cytosol. At the same time, there are two independent pathways for the synthesis of isoprenoids: mevalonate - in the cytoplasm, alternative - in plastids. "Plastid" synthesis of isoprenoids is often carried out in leukoplasts - specialized "isoprenoid" plastids that have a number of morphological features (for example, the absence of ribosomes, a special arrangement of internal membranes). They are characterized by close contacts with the ER (“reticular sheath”), which indirectly indicates the interaction of plastids and ER during the synthesis of isoprenoids.

Rice. 3. Structure of some sesquiterpenoids and diterpenoids

Phenolic compounds are substances of an aromatic nature containing one or more hydroxyl groups at the aromatic ring. Phenols are compounds with one hydroxyl atom, polyphenols - with two or more. Many phenolic compounds are involved in the main metabolism (in particular, in the processes of photosynthesis and respiration), but most of them are typical representatives of the secondary metabolism.

Phenolic compounds are classified according to the number of aromatic rings and the number of carbon atoms attached to them. Phenolic compounds are usually divided into three large subgroups: with one and two aromatic rings, as well as polymeric phenolic compounds. Sometimes dimeric phenolic compounds are distinguished into a special group.

A distinctive feature of phenolic compounds is the formation of a huge number of compounds due to modifications of the molecule and the formation of conjugates with various structures. Of the modifications for phenolic compounds, the formation of glycosides, methylation and methoxylation are characteristic. Due to hydroxyl and carboxyl groups, phenolic compounds can bind with sugars, organic acids, plant amines, and alkaloids. In addition, plant phenols can combine with isoprenoids to form a large group of prenylated phenols. Such properties of phenolic compounds provide a huge variety of structures characteristic of plant phenols.

Phenolic compounds accumulate both in vacuoles and in the periplasmic space. In this case, vacuoles usually contain glycosylated phenolic compounds, while the periplasmic space contains metaxylated compounds or aglycones. Synthesis of phenolic compounds occurs in chloroplasts and cytosol. The existence of two independent pathways for the synthesis of aromatic compounds (shikimate pathways) has been shown - in the cytosol and in plastids.

Many compounds of other classes of secondary metabolites also accumulate in vacuoles. Similar localization have, for example, cyanogenic glycosides, glucosinolates, betalains.

Rice. 4. Phenolic compounds with two aromatic rings: stilbenes (A), anthraquinones (B), main groups of flavonoids (C), anthocyanidins (D)

Minor groups of secondary metabolites

vegetable amines. Higher plants contain a large number of amines - primary, secondary, tertiary and quaternary. Many of them are structurally decarboxylated amino acids, both protein and non-protein. Plant amines are divided into monoamines (with one amino group), diamines (with two amino groups) and polyamines.

Betalains. This is the name of the water-soluble nitrogen-containing pigments of higher plants. They are present only in plants of the order Carnation.

Until now, no plants have been found where two groups of water-soluble pigments - anthocyanins and betalains - occur simultaneously. The group of betalains is made up of betacyanins and betaxanthins - red-violet and yellow compounds, respectively. Betacyanins are glycosides and acyl glycosides of only two aglycones.

cyanogenic glycosides. Cyanogenic glycosides are ?-glycosides of 2-hydroxynitriles (cyanohydrins). To date, several dozens of such compounds have been found in higher plants. The main structural variations are due to the nature of the substituents R1 and R2. As a carbohydrate fragment, as a rule, D-glucose acts. During the hydrolysis of cyanogenic glycosides, hydrocyanic acid is released by a specific glycosidase.

non-protein amino acids. This term refers to natural amino acids, their amides, imino acids, which are not normally included in proteins. More than 400 non-protein amino acids are now known. Many of them can be considered as protein modifications. The most common options for lengthening or shortening the carbon chain (adding or removing CH2 or CH3 fragments), hydrogenation and dehydrogenation, hydroxylation, amination. There are also unusual (for example, selenium-containing) amino acids. Non-protein amino acids are predominantly very toxic, since they can be included in proteins instead of "normal" amino acids and disrupt their functions.

unusual lipids. These primarily include “unusual” fatty acids, which differ from “ordinary” ones in the length of the carbon chain, in a different arrangement and number of double bonds, and in the presence of additional functional groups and cycles. Most often, unusual fatty acids are found in seed oil. Compounds with one or more triple bonds have been found in many species of higher plants. Such compounds are called acetylene derivatives, or polyacetylenes. Several hundred such structures are known. Unlike uncommon fatty acids, acetylenic derivatives can be found in all organs and parts of a plant. Unusual lipids also include cyanolipids, the hydrolysis of which releases hydrocyanic acid.

Sulfur-containing secondary metabolites. These include primarily thioglycosides (S-glycosides). The most well-known mustard oil glycosides (glucosinolates). These glycosides are characteristic of cruciferous plants. They have a strong antimicrobial effect and cause a sharp or burning taste of mustard, horseradish, radish. The mechanism of action of glucosinolates is very similar to the action of cyanogenic glycosides: after the removal of sugar by myrosinase, isothiocyanates are formed, causing a burning taste and irritating effect. Another group of sulfur-containing secondary metabolites are garlic and onion allicins, which are synthesized from cysteine. They are also responsible for the pungent taste and antimicrobial properties of these plants.

1.6 Biochemistry of secondary metabolism

Biosynthetic pathways for secondary metabolites

Synthesis pathways for most secondary metabolites are well established. Currently, the enzymology of secondary metabolism is being intensively studied. Based on the available information, it is possible to formulate some regularities in the biosynthesis of these compounds. The synthesis precursors are a relatively small number of primary metabolites. Many groups of secondary metabolites can be synthesized in several ways. Often the stages of synthesis are duplicated in different compartments of the cell (for example, plastids - cytosol). Synthesis is well planned and served by a set of special enzymes, in most cases very specific.

Biosynthesis of alkaloids. The formation of these substances is closely related to the overall exchange of nitrogen in the cell. For most alkaloids, it has been shown that the schemes for their synthesis are unified, i.e., they have a similar sequence of reactions. In the process of biosynthesis, the amino acid molecule is almost completely included in the structure of the alkaloid. The synthesis of alkaloids of different groups includes the same types of reactions: decarboxylation, oxidative deamination, aldol condensation, but for each group of alkaloids, these reactions are carried out by "own" enzymes. At the first stage of synthesis, decarboxylation of the amino acid occurs with the participation of the corresponding decarboxylase. The resulting biogenic amines undergo oxidative deamination with the participation of amine oxidases. The resulting amino aldehydes or amino ketones form key heterocyclic compounds through a series of successive reactions. Then the basic structure is modified with the participation of various reactions - hydroxylation, methylation, etc. Additional carbon units, for example, acetate (in the form of acetyl-CoA) or monoterpene unit (for complex indole alkaloids), can take part in the formation of the final structure of the alkaloid. Depending on the complexity of the alkaloid, its biosynthesis includes from three to four to ten to fifteen reactions.

For a number of alkaloids, not only the synthesis scheme has been established, but enzymes have been characterized and isolated. It turned out that some synthesis enzymes are not very specific (different compounds can be used as substrates), however, highly specific enzymes are necessarily present in the synthesis chain, which use only one substrate (or a number of very close substrates) and perform a very specific reaction.

For example, in the synthesis of isoquinolines, the hydroxylation of the basic structure at each position is performed by different enzymes. As we progress to the final stages of synthesis, the affinity of enzymes for the substrate usually increases: for example, for a number of enzymes in the synthesis of berberine alkaloids, Kt is less than 1 μM. As an example, in fig. 5 shows the scheme for the synthesis of isoquinoline alkaloids.

Rice. 5. Scheme of the biosynthesis of isoquinoline alkaloids

Biosynthesis of isoprenoids. If in the synthesis of alkaloids a similar chain of transformations is used for various starting compounds (amino acids), then the synthesis of a colossal number of isoprenoids occurs from a single precursor, isopentenyl diphosphate (IPDP). Under the action of the enzyme isopentenyl diphosphate isomerase, which shifts the double bond, IPDP is converted to dimethylallyl diphosphate (DMADP). Further, IPDP is added to DMADP at the double bond and a C10 compound is formed - geranyl diphosphate.

It serves as the source of all monoterpenoids.

Then another IPDP is added to geranyl diphosphate and the C15 compound farnesyl diphosphate, the starting material for the synthesis of sesquiterpenoids, is formed. Further, farnesyl diphosphate can either attach another IPDP molecule to form geranylgeranyl diphosphate (C20 compound is the source of diterpenoids) or dimerize to form squalene (C30 compound is the parent compound for all triterpenoids). Finally, geranylgeranyl diphosphate can dimerize to form phytoin, a C40 compound, a source of tetraterpenoids. In addition, a large amount of IPDP can be sequentially added to geranylgeranyl diphosphate, eventually forming polyisoprenoids - rubber and gutta-percha. As a result of the described reactions, a complete homologous series of C5 compounds of different lengths is formed. Further, these aliphatic molecules can "fold" into cyclic structures, and the number of cycles, their size, and types of articulation can be very different. On fig. 9.13 shows the general scheme for the synthesis of isoprenoids.

The synthesis of basic isoprenoid structures is carried out by only two types of enzymes - prenyltransferases, which "increase" the length of isoprenoids, and cyclases, which form the corresponding cyclic skeleton of the molecule. Each type of structure is formed by a specific cyclase. Since there are quite a lot of types of cyclic structures of isoprenoids, the number of cyclases should be impressive. To date, more than a hundred of them are known. After the formation of the basic structure (or simultaneously with it), it is modified and “equipped” with functional groups.

Rice. 6. General scheme of isoprenoid biosynthesis (A) and two pathways of isopentenyl diphosphate synthesis (B) in plants

Dots show labeled atoms in the starting compounds and in the resulting IPDF.

Thus, the biosynthesis of isoprenoids can be imagined as a kind of biochemical "modeler-constructor". First, flexible linear structures of different lengths are made from unified C5 modules. They represent an almost ideal material for "biochemical design" and the formation of many variants of cyclic structures.

Plants use both variants of isoprenoid formation: in the cytosol, synthesis proceeds along the classical path, and in plastids, along the alternative one. In this case, not only duplication of isoprenoid synthesis in different cell compartments is possible, but also separation according to the type of synthesized structures. Triterpenoids (including steroids) are synthesized in the cytosol from mevalonate, while diterpenoids (including chlorophyll phytol) and tetraterpenoids (primarily carotenoids) are synthesized in plastids via an alternative pathway. Mono- and sesquiterpenes can probably be formed in different ways, depending on the structure of the molecule and the plant species.

Biosynthesis of phenolic compounds. To date, two pathways for the formation of phenolic compounds are known - shikimate (through shikimic acid) and acetate-malonate. The main route is shikimate, which is practically the only way to form an aromatic ring. The starting compounds for the synthesis are phosphoenolpyruvate (PEP) and erythrose-4-phosphate. When they condense, a seven-carbon acid (2-keto-3-deoxy-7-phosphoaraboheptanoic acid) is formed, which then cyclizes into 5-dehydroquinic acid. From dehydroquinic acid, shikimic acid is formed, which has a six-membered ring, one double bond, and is easily converted into aromatic compounds. From shikimic acid, the formation of hydroxybenzoic acids is possible - n-hydroxybenzoic, protocatechuic, gallic. However, the main way of using shikimic acid is the formation of aromatic amino acids phenylalanine and tyrosine through prefenic acid. Phenylalanine (possibly, in some cases, tyrosine) is the main precursor for the synthesis of phenolic compounds. Deamination of phenylalanine is carried out by the enzyme phenylalanine ammonia lyase (PAL). As a result, cinnamic acid is formed, the hydroxylation of which leads to the formation of para-coumaric (hydroxycinnamic) acid. After additional hydroxylation and subsequent methylation, the remaining hydroxycinnamic acids are formed from it.

Hydroxycinnamic acids represent the central link in the synthesis of all phenolic compounds in the cell. Opto-coumaric acid is a precursor of coumarins. After a series of shortening reactions of the aliphatic part of the molecule, C6-C2- and C6-C1 compounds are formed - this is the second way for the formation of hydroxybenzoic acids (the first is directly from shikimic acid). Hydroxycinnamic acids can form various conjugates, primarily with sugars, but most hydroxycinnamic acids are activated by interaction with CoA. Two main ways of using CoA-esters of hydroxycinnamic acids are the synthesis of lignins and the synthesis of flavonoids. For the synthesis of lignins, CoA esters of hydroxycinnamic acids are reduced to alcohols, which act as synthesis monomers. In the synthesis of flavonoids, the CoA derivative of hydroxycinnamic acid interacts with three molecules of malonyl-CoA to form chalcone. The reaction is catalyzed by the enzyme chalcone synthase. The resulting chalcone is easily converted to flavanone. Other groups of flavonoids are formed from flavanones due to hydroxylation, oxidation-reduction reactions. Then the molecule can be modified - glycosylation, methoxylation, etc.

The acetate-malonate pathway for the synthesis of phenolic compounds is widespread in fungi, lichens, and microorganisms. In plants, it is minor. In the synthesis of compounds along this pathway, acetyl-CoA is carboxylated to form malonylacetyl-CoA. Then a cascade of similar reactions occurs, as a result, the carbon chain grows and poly- ?-ketomethylene chain. Cyclization of the polyketide chain leads to the formation of various phenolic compounds. In this way, phloroglucinol and its derivatives, some anthraquinones are synthesized. In the structure of flavonoids, ring B is formed via the shikimate pathway (from hydroxycinnamic acid), while ring A is formed via the acetate-malonate pathway.

Two shikimate pathways for the synthesis of flavonoids work in the cell - one in plastids, the other in the cytosol. These compartments contain a complete set of isoenzymes of the shikimate pathway, as well as enzymes of phenol metabolism, including PAL and chalcone synthase. Thus, in a plant cell, there are two parallel chains of synthesis of phenolic compounds (similar to isoprenoids).

Synthesis of minor classes of secondary compounds. The formation of these substances has also been studied quite fully. For many nitrogen-containing compounds, the starting materials are amino acids. For example, the synthesis of cyanogenic glycosides begins with the decarboxylation of the corresponding amino acid, then aldoxime, nitrile, and ?-hydroxynitrile. At the last stage of the synthesis, a cyanogenic glycoside is formed due to glycosylation ?-hydroxynitrile with UDP-glucose. Synthesis is usually carried out by a complex of enzymes: for example, for durrin, this complex consists of four enzymes. The enzyme genes have been cloned. Arabidopsis transgenic for two genes acquired the ability to synthesize cyanogenic glycosides. The synthesis of betalains starts from tyrosine, which is hydroxylated to form dihydroxyphenylalanine (DOPA). DOPA serves as a source for two fragments of the betacyanin molecule - betalamic acid and cyclo-DOPA. Combining these two compounds results in the formation of betacyanins. During the synthesis of betaxanthines, betalamic acid condenses with proline. Sulfur-containing secondary metabolites are usually synthesized from sulfur-containing amino acids.

2. Research methods

The bromatometric determination of phenol has great practical application. The determination of phenol is based on the fact that an excess of a bromate-bromide mixture is introduced into the analyzed solution, which releases free bromine in an acidic environment. The resulting bromine reacts with phenol:

C6H5OH + 3Br2 C6H2Br3OH + 3HBr

When potassium iodide is added to this solution, excess unreacted bromine oxidizes the iodide to iodine, which is titrated with a standard solution of sodium thiosulfate:

Br2 + 2I = 2Br + I2+ 2S2O = 2I + S4O

Reagents

Sodium thiosulfate 0.02 M solution (or standardized)*

Bromate-bromide mixture.

Sulfuric acid 1M solution

Starch, 0.5% solution

Potassium iodide, KI (c)

Volumetric flask 500 ml

Flask conical 250-300 ml

Measuring cylinder 20 ml

Pipettes 20 and 25 ml

Burette 25 ml

Completing of the work

A bromate-bromide solution can be prepared by weighing: 0.334 g. KBrO3 and 1.2 KBr are dissolved in distilled water and brought to the mark in a 500 ml volumetric flask, in this case the concentration is approximately 0.024 M. To obtain the same concentration, the solution can be prepared from fixanal KBrO3 - KBr 0.1 N but in this case the contents of the sealed ampoule must be dissolved in 4 liters of distilled water.

For analysis, an aliquot (10 ml) of a solution containing 0.02-0.4 g/l of phenol** is taken with a pipette into a conical titration flask. Add 12 ml (with a pipette) of bromate-bromide mixture, 10 ml of 1M sulfuric acid solution, stopper and leave for 30 minutes. Then add 1 g of potassium iodide, weighed on a technical balance, and again stopper. After 5 minutes, the released iodine is titrated with a solution of sodium thiosulfate, adding at the end of the titration, when the color of the solution becomes light yellow, 2-3 ml of starch solution. Titration is continued until the blue color of the solution disappears. Three titrations are carried out and the mean volume V1 is calculated from the converging results.

3. Practical task

Secondary metabolites include antibiotics, alkaloids, plant growth hormones, and toxins.

2. Protein biosynthesis occurs in ribosomes.

3. Photosynthesis occurs in the leaf, in the cells of the leaf, in the chloroplasts, which contain the green pigment chlorophyll.

4. The unit of photosynthesis is the quantosome.

The anaerobic phase of respiration is a sequence of reactions called glycolysis.

In the process of glycolysis, a hexose molecule is converted to two molecules of pyruvic acid:

С6Н12О6?2С3Н4О2 + 2H2.

This oxidative process can take place under anaerobic conditions.

Conclusion

As a result of the completed course work, I learned what secondary metabolites are, as well as the features of secondary metabolites, which include: relatively low molecular weight (an exception is, for example, high molecular weight polyisoprenoids: rubber, gutta-percha, chicle); not necessarily present in every organism (some secondary metabolites are widespread, for example, many phenylpropanoids are found in almost all plants); as a rule, are biologically active substances; synthesized from primary metabolites.

These signs are not mandatory, however, taken together, they quite clearly outline the range of secondary metabolites.

In plants, secondary metabolites are involved in the interaction of the plant with the environment, defense reactions (for example, poisons). These include the following classes: alkaloids, isoprenoids, phenolic compounds, minor compounds (there are 10-12 groups, in particular: non-protein amino acids, biogenic amines, cyanogenic glycosides, mustard oil glycosides (isothiocyanates), betalains, cyanolipids, acetogenins, acetylenic derivatives, allicins, acetophenones, thiophenes, unusual fatty acids, etc.)

synthesis of phenolic alkaloids biochemical

List of used literature

1."Microbiology: a dictionary of terms", Firsov N.N., M: Bustard, 2006

2.Medicinal raw materials of plant and animal origin. Pharmacognosy: textbook / ed. G.P. Yakovleva. St. Petersburg: SpecLit, 2006. 845 p.

.Shabarova ZA, Bogdanov AA, Zolotukhin AS Chemical foundations of genetic engineering. - M.: Publishing House of Moscow State University, 2004, 224 p.

4.Chebyshev N.V., Grineva G.G., Kobzar M.V., Gulyankov S.I. Biology. M., 2000

Tutoring

Need help learning a topic?

Our experts will advise or provide tutoring services on topics of interest to you.
Submit an application indicating the topic right now to find out about the possibility of obtaining a consultation.

A number of cell metabolites are of interest as target fermentation products. They are divided into primary and secondary.

Primary metabolites- These are low molecular weight compounds (molecular weight less than 1500 daltons) necessary for the growth of microorganisms. Some of them are the building blocks of macromolecules, others are involved in the synthesis of coenzymes. Among the most important metabolites for industry are amino acids, organic acids, nucleotides, vitamins, etc.

The biosynthesis of primary metabolites is carried out by various biological agents - microorganisms, plant and animal cells. In this case, not only natural organisms are used, but also specially obtained mutants. To ensure high concentrations of the product at the stage of fermentation, it is necessary to create producers that resist the regulatory mechanisms genetically inherent in their natural form. For example, it is necessary to eliminate the accumulation of an end product that represses or inhibits an important enzyme in order to obtain the target substance.

Production of amino acids.

Auxotrophs (microorganisms that require growth factors to reproduce) produce many amino acids and nucleotides during fermentations. Common objects for selection of amino acid producers are microorganisms belonging to the genera Brevibacterium, Corynebacterium, Micrococcus, Arthrobacter.

Of the 20 amino acids that make up proteins, eight cannot be synthesized in the human body (essential). These amino acids must be supplied to the human body with food. Among them, methionine and lysine are of particular importance. Methionine is produced by chemical synthesis, and more than 80% of lysine is produced by biosynthesis. The microbiological synthesis of amino acids is promising, since as a result of this process, biologically active isomers (L-amino acids) are obtained, and during chemical synthesis, both isomers are obtained in equal amounts. Since they are difficult to separate, half of the production is biologically useless.

Amino acids are used as food additives, seasonings, flavor enhancers, as well as raw materials in the chemical, perfumery and pharmaceutical industries.

The development of a technological scheme for obtaining a single amino acid is based on knowledge of the ways and mechanisms of regulation of the biosynthesis of a particular amino acid. The necessary imbalance of metabolism, which ensures the oversynthesis of the target product, is achieved by strictly controlled changes in the composition and environmental conditions. For the cultivation of strains of microorganisms in the production of amino acids, carbohydrates are the most available as carbon sources - glucose, sucrose, fructose, maltose. To reduce the cost of the nutrient medium, secondary raw materials are used: beet molasses, milk whey, starch hydrolysates. The technology of this process is being improved towards the development of cheap synthetic nutrient media based on acetic acid, methanol, ethanol, n-paraffins.

Production of organic acids.

Currently, a number of organic acids are synthesized by biotechnological methods on an industrial scale. Of these, citric, gluconic, ketogluconic and itaconic acids are obtained only by a microbiological method; milk, salicylic and acetic - both by chemical and microbiological methods; malic - chemically and enzymatically.

Acetic acid is the most important among all organic acids. It is used in the manufacture of many chemicals, including rubber, plastics, fibers, insecticides, and pharmaceuticals. The microbiological method for producing acetic acid consists in the oxidation of ethanol to acetic acid with the participation of bacteria strains Gluconobacter And Acetobacter:

Citric acid is widely used in the food, pharmaceutical and cosmetic industries, used to clean metals. The largest producer of citric acid is the USA. The production of citric acid is the oldest industrial microbiological process (1893). For its production use the culture of the fungus Aspergillus niger, A. wentii. Nutrient media for the cultivation of citric acid producers contain cheap carbohydrate raw materials as a carbon source: molasses, starch, glucose syrup.

Lactic acid is the first of the organic acids, which began to be produced by fermentation. It is used as an oxidizing agent in the food industry, as a mordant in the textile industry, and also in the production of plastics. Microbiologically, lactic acid is obtained from the fermentation of glucose Lactobacillus delbrueckii.

under the metabolism or metabolism, understand the totality of chemical reactions in the body, providing it with substances to build the body and energy to maintain life. Part of the reactions turns out to be similar for all living organisms (formation and cleavage of nucleic acids, proteins and peptides, as well as most carbohydrates, some carboxylic acids, etc.) and is called primary metabolism (or primary metabolism).

In addition to primary metabolic reactions, there are a significant number of metabolic pathways leading to the formation of compounds that are characteristic only of certain, sometimes very few, groups of organisms.

These reactions, according to I. Chapek (1921) and K. Pah (1940), are combined by the term secondary metabolism , or exchange, and their products are called products secondary metabolism, or secondary compounds (sometimes secondary metabolites).

Secondary connections are formed mainly in vegetatively inactive groups of living organisms - plants and fungi, as well as in many prokaryotes.

In animals, secondary metabolic products are rarely formed, but often come from outside along with plant foods.

The role of products of secondary metabolism and the reasons for their appearance in a particular group are different. In the most general form, they are assigned an adaptive value and, in a broad sense, protective properties.

The rapid development of the chemistry of natural compounds over the past three decades, associated with the creation of high-resolution analytical instruments, has led to the fact that the world "secondary connections" expanded significantly. For example, the number of alkaloids known today is close to 5,000 (according to some sources, to 10,000), phenolic compounds - to 10,000, and these numbers are growing not only every year, but also every month.

Any plant material always contains a complex set of primary and secondary compounds, which, as already mentioned, determine the versatile nature of the action of medicinal plants. However, the role of both in modern phytotherapy is still different.

Relatively few objects are known, the use of which in medicine is determined primarily by the presence of primary compounds in them. However, in the future, their role in medicine and their use as sources for obtaining new immunomodulating agents cannot be ruled out.

Secondary metabolic products are used in modern medicine much more often and more widely. This is due to their tangible and often very "bright" pharmacological effect.

Being formed on the basis of primary compounds, they can either accumulate in a pure form or undergo glycosylation during exchange reactions, i.e. are attached to a sugar molecule.

As a result of glycosylation, molecules arise - heterosides, which differ from secondary compounds, as a rule, in better solubility, which facilitates their participation in metabolic reactions and is of great biological importance in this sense.

Glycosylated forms of any secondary compounds are called glycosides.

Substances of primary synthesis are formed in the process of assimilation, i.e. the transformation of substances entering the body from the outside into the substances of the body itself (cell protoplast, reserve substances, etc.).

Substances of primary synthesis include amino acids, proteins, lipids, carbohydrates, enzymes, vitamins and organic acids.

Lipids (fats), carbohydrates (polysaccharides) and vitamins are widely used in medical practice (the characteristics of these groups of substances are given in the relevant topics).

Squirrels, along with lipids and carbohydrates, make up the structure of cells and tissues of a plant organism, participate in biosynthesis processes, and are an effective energy material.

Proteins and amino acids of medicinal plants have a non-specific beneficial effect on the patient's body. They affect the synthesis of proteins, create conditions for enhanced synthesis of immune bodies, which leads to an increase in the body's defenses. Improved protein synthesis also includes increased enzyme synthesis, resulting in improved metabolism. Biogenic amines and amino acids play an important role in the normalization of nervous processes.

Squirrels- biopolymers, the structural basis of which is long polypeptide chains built from α-amino acid residues interconnected by peptide bonds. Proteins are divided into simple (only amino acids are produced during hydrolysis) and complex - in them, the protein is associated with non-protein substances: with nucleic acids (nucleoproteins), polysaccharides (glycoproteins), lipids (lipoproteins), pigments (chromoproteins), metal ions (metaloproteins) , phosphoric acid residues (phosphoproteins).

At the moment, there are almost no objects of plant origin, the use of which would be determined by the presence of mainly proteins in them. However, it is possible that in the future modified plant proteins can be used as a means of regulating the metabolism in the human body.

Lipids - fats and fat-like substances derived from higher fatty acids, alcohols or aldehydes.

They are divided into simple and complex.

To simple are lipids whose molecules contain only residues of fatty acids (or aldehydes) and alcohols. From simple lipids in plants and animals, fats and fatty oils are found, which are triacylglycerols (triglycerides) and waxes.

The latter consist of esters of higher fatty acids of mono- or dihydric higher alcohols. Prostaglandins, which are formed in the body from polyunsaturated fatty acids, are close to fats. By chemical nature, these are derivatives of prostanic acid with a skeleton of 20 carbon atoms and containing a cyclopentane ring.

Complex lipids divided into two large groups:

phospholipids and glycolipids (i.e., compounds that have a phosphoric acid residue or a carbohydrate component in their structure). As part of living cells, lipids play an important role in life support processes, forming energy reserves in plants and animals.

Nucleic acids- biopolymers, the monomeric units of which are nucleotides consisting of a phosphoric acid residue, a carbohydrate component (ribose or deoxyribose) and a nitrogenous (purine or pyrimidine) base. There are deoxyribonucleic (DNA) and ribonucleic (RNA) acids. Nucleic acids from plants have not yet been used for medicinal purposes.

Enzymes occupy a special place among proteins. The role of enzymes in plants is specific - they are catalysts for most chemical reactions.

All enzymes are divided into 2 classes: one-component and two-component. Single-component enzymes are made up of only protein

two-component - from a protein (apoenzyme) and a non-protein part (coenzyme). Coenzymes can be vitamins.

In medical practice, the following enzyme preparations are used:

- "Nigedaza " - from the seeds of Nigella damask - Nigella damascena, fam. ranunculaceae - Ranunculaceae. At the heart of the preparation is an enzyme of lipolytic action, which causes the hydrolytic breakdown of fats of vegetable and animal origin.

The drug is effective in pancreatitis, enterocolitis and age-related decrease in the lipolytic activity of the digestive juice.

- "Karipazim" and "Lekozim" - from dried milky juice (latex) of papaya (melon tree) - Carica papaya L., fam. papaya - Cariacaceae.

At the heart of "Karipazim"- the amount of proteolytic enzymes (papain, chymopapain, peptidase).

It is used for burns of the III degree, accelerates the rejection of scabs, cleanses granulating wounds from purulent-necrotic masses.

At the heart of Lekozima"- the proteolytic enzyme papain and the mucolytic enzyme lysozyme. They are used in orthopedic, traumatological and neurosurgical practice for intervertebral osteochondrosis, as well as in ophthalmology for resorption of exudates.

organic acids, along with carbohydrates and proteins, are the most common substances in plants.

They take part in the respiration of plants, the biosynthesis of proteins, fats and other substances. Organic acids belong to substances of both primary synthesis (malic, acetic, oxalic, ascorbic) and secondary synthesis (ursolic, oleanolic).

Organic acids are pharmacologically active substances and participate in the total effect of drugs and medicinal forms of plants:

Salicylic and ursolic acids have anti-inflammatory effects;

Malic and succinic acids - donors of energy groups, help to increase physical and mental performance;

Ascorbic acid is vitamin C.

vitamins- a special group of organic substances that perform important biological and biochemical functions in living organisms. These organic compounds of various chemical nature are synthesized mainly by plants and also by microorganisms.

Humans and animals that do not synthesize them require very small amounts of vitamins compared to nutrients (proteins, carbohydrates, fats).

More than 20 vitamins are known. They have letter designations, chemical names and names characterizing their physiological action. Vitamins are classified on water-soluble (ascorbic acid, thiamine, riboflavin, pantothenic acid, pyridoxine, folic acid, cyanocobalamin, nicotinamide, biotin)

and fat-soluble (retinol, phylloquinone, calciferols, tocopherols). To vitamin-like substances belong to some flavonoids, lipoic, orotic, pangamic acids, choline, inositol.

The biological role of vitamins is diverse. A close relationship has been established between vitamins and enzymes. For example, most B vitamins are precursors of coenzymes and prosthetic groups of enzymes.

Carbohydrates- an extensive class of organic substances, which includes polyoxycarbonyl compounds and their derivatives. Depending on the number of monomers in a molecule, they are divided into monosaccharides, oligosaccharides and polysaccharides.

Carbohydrates, consisting exclusively of polyoxycarbonyl compounds, are called homosides, and their derivatives, in the molecule of which there are residues of other compounds, are called heterosides. Heterosides include all types of glycosides.

Mono- and oligosaccharides are normal components of any living cell. In those cases when they accumulate in significant quantities, they are referred to as the so-called ergastic substances.

Polysaccharides, as a rule, always accumulate in significant quantities as protoplast waste products.

Monosaccharides and oligosaccharides are used in their pure form, usually in the form of glucose, fructose and sucrose. Being energy substances, mono- and oligosaccharides, as a rule, are used as fillers in the manufacture of various dosage forms.

Plants are sources of these carbohydrates (sugar cane, beets, grapes, hydrolyzed wood of a number of conifers and woody angiosperms).

Various forms are synthesized in plants polysaccharides, which differ from each other both in structure and in their functions. Polysaccharides are widely used in medicine in various forms. In particular, starch and its hydrolysis products are widely used, as well as cellulose, pectin, alginates, gums and mucus.

Cellulose (fiber) - a polymer that makes up the bulk of plant cell walls. It is believed that the cellulose molecule in different plants contains from 1400 to 10,000 β-D-glucose residues.

starch and inulin are storage polysaccharides.

Starch is 96-97.6% composed of two polysaccharides: amylose (linear glucan) and amylopectin (branched glucan).

It is always stored in the form of starch grains during active photosynthesis. The representatives of the family Asteraseae And Satrapi/aseae fructosans (inulin) accumulate, especially in large quantities in underground organs.

Slime and gums (gum) - mixtures of homo- and heterosaccharides and polyuronides. Gums consist of heteropolysaccharides with the obligatory participation of uronic acids, the carbonyl groups of which are linked with Ca 2+, K + and Mg 2+ ions.

According to their solubility in water, gums are divided into 3 groups:

Arabic, highly soluble in water (apricot and Arabian);

Bassoriaceae, poorly soluble in water, but strongly swelling in it (tragacanth)

And cerazin, poorly soluble and poorly swelling in water (cherry).

Slime, unlike gums, can be neutral (do not contain uronic acids), and also have a lower molecular weight and are highly soluble in water.

pectin substances- high molecular weight heteropolysaccharides, the main structural component of which is β-D-galacturonic acid (polygalacturonide).

In plants, pectin substances are present in the form of insoluble protopectin, a polymer of methoxylated polygalacturonic acid with galactan and cell wall araban: polyuronide chains are interconnected by Ca 2+ and Mg 2+ ions.

Substances of secondary metabolism

Substances of secondary synthesis produced in plants as a result of

Dissimilation.

Dissimilation is the process of decay of substances of primary synthesis to simpler substances, accompanied by the release of energy. From these simple substances, with the expenditure of released energy, substances of secondary synthesis are formed. For example, glucose (a substance of primary synthesis) decomposes to acetic acid, from which mevalonic acid is synthesized and, through a number of intermediate products, all terpenes.

The substances of secondary synthesis include terpenes, glycosides, phenolic compounds, alkaloids. All of them are involved in metabolism and perform certain important functions for plants.

Substances of secondary synthesis are used in medical practice much more often and more widely than substances of primary synthesis.

Each group of plant substances is not isolated and is inextricably linked with other groups of biochemical processes.

For example:

Most phenolic compounds are glycosides;

Bitters from the class of terpenes are glycosides;

Plant steroids are terpenes in origin, while cardiac glycosides, steroidal saponins and steroidal alkaloids are glycosides;

Carotenoids derived from tetraterpenes are vitamins;

Monosaccharides and oligosaccharides are part of glycosides.

Substances of primary synthesis contain all plants, substances of secondary

This synthesis is accumulated by plants of certain species, genera, and families.

Secondary metabolites are formed mainly in vegetatively inactive groups of living organisms - plants and fungi.

The role of products of secondary metabolism and the reasons for their appearance in one or another systematic group are different. In the most general form, they are assigned an adaptive meaning and, in a broad sense, protective properties.

In modern medicine, secondary metabolic products are used much more widely and more often than primary metabolites.

This is often associated with a very pronounced pharmacological effect and multiple effects on various systems and organs of humans and animals. They are synthesized on the basis of primary compounds and can accumulate either in free form, or undergo glycosylation during metabolic reactions, i.e., they bind to some sugar.

alkaloids - nitrogen-containing organic compounds of a basic nature, mainly of plant origin. The structure of alkaloid molecules is very diverse and often quite complex.

Nitrogen, as a rule, is located in heterocycles, but sometimes is located in the side chain. Most often, alkaloids are classified based on the structure of these heterocycles, or in accordance with their biogenetic precursors - amino acids.

The following main groups of alkaloids are distinguished: pyrrolidine, pyridine, piperidine, pyrrolizidine, quinolizidine, quinazoline, quinoline, isoquinoline, indole, dihydroindole (betalaines), imidazole, purine, diterpene, steroid (glycoalkaloids) and alkaloids without heterocycles (protoalkaloids). Many of the alkaloids have specific, often unique physiological effects and are widely used in medicine. Some alkaloids are strong poisons (for example, curare alkaloids).

Anthracene derivatives- a group of natural compounds of yellow, orange or red color, which are based on the structure of anthracene. They can have different oxidation states of the middle ring (derivatives of anthrone, anthranol, and anthraquinone) and carbon skeleton structure (monomeric, dimeric, and condensed compounds). Most of them are derivatives of chrysacin (1,8-dihydroxyanthraquinone). Alizarin (1,2-dihydroxyanthraquinone) derivatives are less common. Anthracene derivatives can be found in plants in the free form (aglycones) or in the form of glycosides (anthraglycosides).

Withanolides - a group of phytosteroids. Currently, several series of this class of compounds are known. Withanolides are polyoxysteroids that have a 6-membered lactone ring in position 17, and a keto group at C 1 in the A ring.

Glycosides - widespread natural compounds that decompose under the influence of various agents (acid, alkali or enzyme) into a carbohydrate part and aglycone (genin). The glycosidic bond between sugar and aglycone can be formed with the participation of O, N or S atoms (O-, N- or S-glycosides), as well as due to C-C atoms (C-glycosides).

O-glycosides are the most widespread in the plant world). Between themselves, glycosides can differ both in the structure of the aglycone and in the structure of the sugar chain. The carbohydrate components are represented by monosaccharides, disaccharides and oligosaccharides, and, respectively, glycosides are called monosides, biosides and oligosides.

Peculiar groups of natural compounds are cyanogenic glycosides And thioglycosides (glucosinolates).

Cyanogenic glycosides can be presented as derivatives of α-hydroxynitriles containing hydrocyanic acid in their composition.

They are widely distributed among plants of this family. Ros aceae, subfamily Pripoidae, concentrating predominantly in their seeds (for example, the glycosides amygdalin and prunazine in the seeds Atyrgdalus sottinis, Arteniaca vi1garis).

thioglycosides (glucosinolates)) are currently considered as derivatives of a hypothetical anion - glucosinolate, hence the second name.

Glucosinolates have been found so far only in dicotyledonous plants and are characteristic of the family. Brassy saseae, Sarraridaseae, Resedaceae and other representatives of the order Sarapales.

In plants, they are found in the form of salts with alkali metals, most often with potassium (for example, glucosinolate sinigrin from seeds Brassica jipsea And V.nigra.

Isoprenoids - an extensive class of natural compounds considered

taken as a product of the biogenic conversion of isoprene.

These include various terpenes, their derivatives - terpenoids and steroids. Some isoprenoids are structural fragments of antibiotics, some are vitamins, alkaloids and animal hormones.

Terpenes and terpenoids- unsaturated hydrocarbons and their derivatives of the composition (C 5 H 8) n, where n \u003d 2 or n\u003e 2. According to the number of isoprene units, they are divided into several classes: mono-, sesqui-, di-, tri-, tetra - and polyterpenoids.

Monoterpenoids (C 10 H 16) and sesquiterpenoids (C 15 H 24) are common components of essential oils.

Bacterial growth is the division of a cell into two daughter cells, genetically completely identical to the original mother cell. Under optimal conditions, the bacterial population doubles every 9.8 minutes. On average, the growth of a bacterial population is described by an exponential law.

The growth of microorganisms-producers (the dependence of the logarithm of the number of cells on time) has the form of an S-shaped curve. There are four growth phases - 1 - lag-phase, 2 - exponential growth phase or log-phase, 3 - stationary phase, 4 - dying phase. During the 1st lag-phase (addiction), bacteria adapt to new conditions, synthesis of RNA, enzymes and other biologically important compounds takes place. 2nd phase - exponential phase - the period of cell doubling, the dependence of the logarithm of the number of cells on time is a straight line. Obviously, the growth of microorganisms cannot continue indefinitely due to the depletion of the nutrient medium and the accumulation of toxic metabolic products. During the 3rd, stationary phase, the rates of growth and death of cells are aligned, and the number of cells remains constant. The last phase is the 4th - the dying phase - a decrease in the number of cells due to the depletion of the nutrient medium.

Metabolites, usually small molecules, are intermediates or products of metabolism. Distinguish primary and secondary metabolites. Primary metabolites (amino acids, nucleotides) are directly involved in the processes of cell growth and development. Secondary metabolites (antibiotics, alkaloids, steroids, pigments) are not essential for cell growth.

Unlike the synthesis primary metabolite that occurs simultaneously with the growth and reproduction of culture, for the producer of secondary metabolites, it is customary to speak of a trophic phase (when the culture grows and multiplies) and an idiophase (when growth slows down or stops and product synthesis begins). The mechanisms for switching metabolic pathways from primary to secondary are not clear.

Rice. one. Comparative characteristics of growth curves of microorganisms.

I- growth curve of microorganisms upon receipt of primary metabolites: 1 – lag phase, 2 – exponential growth phase or log phase, 3 – stationary phase, 4 – dying phase. II– growth curve of microorganisms upon receipt of secondary metabolites(shorter growth phase and longer stationary phase).

Microorganisms that produce secondary metabolites first go through a stage of rapid growth, a trophic phase, during which the synthesis of secondary metabolites is negligible. As growth slows due to the depletion of one or more essential nutrients in the culture medium, the microorganism enters the idiophase; it is during this period that idiolytes (secondary metabolites) are synthesized. Soantibiotics most rapidly accumulate in the medium during the stationary phase, when the biomass almost does not increase. Idiolites do not play a clear role in metabolic processes, they are produced by cells to adapt to environmental conditions, for example, for protection. They are synthesized not by all microorganisms, but mainly by filamentous bacteria, fungi and spore-forming bacteria.

Rice. 2. Features of the fermentation process in the production of antibiotics:

1 - trophic phase, II - idiophase, 1 - cell biomass, 2 - antibiotic, 3 - carbohydrates, 4 - nitrogen sources.

Features of the cultural growth of microorganisms-producers must be taken into account during production. For example, in the case of antibiotics, most microorganisms during the trophophase process are sensitive to their own antibiotics, but during the idiophase they become resistant to them.

To prevent antibiotic-producing organisms from self-destructing, it is important to quickly reach the idiophase and then culture the organisms in that phase. This is achieved by varying the cultivation regimes and the composition of the nutrient medium at the stages of fast and slow growth.