Simple phenolic compounds. Phenolic compounds - lecture. Phenolic compounds, their characteristics and prevalence in nature

Simple phenolic compoundsare compounds with one benzene ring having a structure of C 6, C 6 -C 1, C 6 -C 2, C 6 -C 3. The simplest phenolic compounds with one benzene ring and one or more hydroxyl groups in plants are rare, more often they are in bound form (in the form of glycosides or esters), or they are structural units of more complex compounds. The most widely represented plants are phenological glycosides, compounds in which the hydroxyl group is bound to sugar. Classification of simple phenolic compounds is presented in the diagram.

Classification of simple phenolic compounds

I. C 6 - row - phenols.

1. Monatomic phenols (monophenols).Contained in cones of spruce, fruits and flowers of black currant, some lichens.

2. Diatomic phenols (diphenols):

a) 1,2-dihydroxybenzene

Catechol

Contained in onion scales, horsetail ephedra grass, in plants of the heather, rosaceae, and asteraceae families.

b) 1,4-dihydroxybenzene

Hydroquinone

Hydroquinone and its derivatives are found in plants of the heather, rosaceae, saxifrage, and asteraceae families.

Hydroquinone is an aglycon of arbutin - a glycoside contained in the leaves and shoots of bearberry and lingonberry. Bearberry also contains methylarbutin.

3. Triatomic phenols (triphenols)- 1,3,5-trihydroxybenzene - phloroglucinol.

Triatomic phenols are found in plants, usually in the form of derivatives of phloroglucin. The simplest compound is aspidinol containing one phloroglucinol ring.

Aspidinol

Mixtures of various derivatives of phloroglucin are called phloroglucides. Accumulate in large quantities in ferns, are the active substances of the male thyroid.

II. C 6 -C 1 - a number - phenolic acids, alcohols, aldehydes.

Widely distributed in medicinal plants of the families of beech, bean, sumac, rosaceae, violet, heather. Phenolic acids are found in almost all plants.

III. C 6 -C 2 - a number - phenylacetic acids and alcohols.

Coupleβ-tyrazole is an aglycon of the glycoside salidroside (rhodioloside) - the main active substance of the rhizomes and roots of Rhodiola rosea.

IV. C 6 -C 3 - a number - hydroxycinnamic acids.

Found in almost all plants, such as acids couplecoumarine ( couple-hydroxycinnamic), coffee and chlorogenic.

Coffee acid

Hydroxycinnamic acids have antimicrobial and antifungal activity, exhibit antibiotic properties. Hydroxycinnamic acids and their esters have a targeted effect on the function of the kidneys, liver and biliary tract. Contained in the grass of horsetail, St. John's wort grass, tansy flowers, flowers of the Helichrysum sandy, artichoke leaves.

V.   Gossypol, which is contained in large quantities in the bark of cotton roots (Gossypium) from the family of malvaceae (Malvaceae), also belongs to simple phenolic compounds. This is a dimeric compound containing phenol:

Lecture No. 4. Medicinal plants and raw materials containing phenolic compounds.
Medicinal plants and raw materials containing phenolic compounds Medicinal plants and raw materials containing simple phenols and phenological glycosides
Lecture plan
1. Classification of phenolic compounds

2 Medicinal plants and raw materials containing simple phenols and

3. Medicinal plants and raw materials containing phenological glycosides

Phenolic compounds   - substances of aromatic nature containing one or more hydroxyl groups bound to atomscarbon aromatic core.   Phenolic compounds, in the aromatic ring of which there is more than one hydroxyl group, are called polyphenols. The number of natural phenolic compounds of plant origin turned out to be so large, and their functions are so diverse that their study requires the involvement of a wide range of researchers.

Currently, it is proved that all polyphenols, with a few exceptions, are active metabolites of cell metabolism and play a significant role in various physiological processes - photosynthesis, respiration, growth, and plant resistance to infectious diseases. The important biological role of polyphenols is evidenced by the nature of their distribution in the plant. Most of them are contained in actively functioning organs - leaves, flowers (color the flowers), fruits, seedlings, and integumentary tissues that perform protective functions. Different organs and tissues differ not only in the number of polyphenols, but also in their qualitative composition.

The diagram shows that the biosynthesis of many groups of phenolic compounds (including flavonoids, coumarins, etc.) is preceded by the formation of amino acids - L-phenylalanine and L-tyrosine. The diagram also shows the site of formation of certain vitamins (K, tocopherols).

The classification of phenolic compounds is based on the main carbon skeleton - the number of aromatic rings and carbon atoms in the side chain. According to these signs, phenolic compounds are divided into groups:
Simple phenols

Simple phenols are rare in plants, and their distribution from a systematic point of view is random. Phenol itself was found in the needles and cones of Pinus sylvestris, essential oils of the leaves of Nicotianatabacum, Ribes nigrum, lichen Evemia prunastri, etc. Pyrocatechin (1,2-di-hydroxybenzene) was found in ephedra leaves, onion scales, and grapefruit fruits. There is no information on the content of resorcinol in plants.

Of the dioxibenzenes, the most common hydroquinone (1,4-dioxibenzol). Its glycoside arbutin is present in representatives of the following families: Ericaceae (Arctostaphylos, Rhododendron); Vacciniaceae (Vaccinium); Rosaceae (Pyrus, Docynia); Saxifragaceae (Bergenia); Asteraceae (Xanthium).

Hydroquinone methyl and ethyl esters are found in the families Ru-rolaceae - Pyrola; Liliaceae -Hyacinthus; Illiciaceae - Illicium.

Of trioxybenzenes, phloroglucinol (1,3,5-trio-sibenzene) is found in plants. In free form, it was found in cones of Sequoia sempervirens and scales of Allium sulfur, and in the form of florin glycoside in the pericarp of fruits of various species of Citrus. A special place is taken by some ferns. They accumulate significant amounts of phloroglucin derivatives, collectively known as phloroglucides. The composition of the molecule of phloroglucides, in addition to phloroglucin (mostly methylated), includes butyric acid.

Bearberry leaves -Folia Uvae ursi

Plant.Bearberry, or bear’s ear, - Arctostaphy-los uva-ursi (L.) Spreng .; heather family - Ericaceae

Evergreen, branched, creeping shrub or shrub. The leaves are small, dark green, leathery. The flowers are pinkish, drooping, collected in short apical brushes. Calyx and whisk 5-toothed; corolla pitcherine, spineless. Fruits - red, berry-like coenocarpous multi-shoots with the remaining cup, with 5 seeds in mealy, inedible pulp. It blooms in the second half of April - May; berries ripen by August.

Distributed in the forest zone of the European part of Russia and the Baltic states, in Western Siberia and less often in the Far East

Chemical composition. INthe leaves contain 8-16% of glycosides - arbutin (hydroquinone-glucoside), methylarbutin, free hydroquinone, gallic acid, ellagic acid and flavonoids, including hyperoside.
The leaves are obovate or narrow obovate in shape, narrowed to the base, short-grained, whole-edge, shiny above, dark green, bare, the upper surface of the sheet with a network of pressed veins; on the underside a little lighter, matte, bare. Leaf length is about 2 cm, width is about 1 cm. Yellow or blackened leaves are a sign of oxidation and other destruction of arbutin, methylarbutin and tannins.

As impurities within the permissible amount (not more than 0.5%), raw materials can contain leaves of lingonberry, blueberry, blueberry, which are easily recognizable by external signs. The leaves of blueberry (Vacciniumuliginosum L.) are wider than the leaves of bearberry, oval-ovoid in shape, whole-edge, non-greasy and non-shiny; blueberries (Vaccinium myrtillus L.) are ovoid, thin with a fine-toothed margin, light green on both sides. GF XI provides for whole and ground raw materials, which should contain at least 6% arbutin.

Application.The leaves are used in the form of decoctions for inflammatory diseases of the bladder and urinary tract. The therapeutic (antiseptic) effect is due to hydroquinone released in the body during the hydrolysis of arbutin and methylarbutin under the action of enzymes and acids. Irritating to the renal epithelium, arbutin also has a diuretic effect. The therapeutic effect is enhanced by the specific action of tannins and their hydrolysis products. Included in diuretic fees.

Lingonberry leaves -Folia Vitis idaeae

Plant.Lingonberry - Vaccinium vitis idaea L .; lingonberry family - Vacciniaceae

Shrub with creeping thin rhizome and erect stems. The leaves are evergreen. Flowers with a pale pink, bell-shaped nimbus are collected in drooping hands; unlike bearberry, the perianth is four-membered. The fruit is a red juicy berry. It blooms in April - May.

The plant is widespread throughout the forest zone of the CIS and Baltic countries.

Chemical composition.Lingonberry leaves contain 6-9% arbutin, hydroquinone, gallic and ellagic acids, tannins (up to 9%), flavonoids, ursolic acid.

Medicinal raw materials.Leaves are harvested at the same time as bearberry leaves. They are elliptical in shape, all-extreme, the edges slightly curled to the underside, glabrous, smooth, dark green on top; the lower surface is light green, covered with numerous brown or black dots (containers). The smell is absent, astringent, bitter taste.

In addition to whole leaves, briquettes obtained by pressing large powder of lingonberry leaves are supplied to pharmacies. GF XI provides for whole and ground raw materials, which should contain at least 4.5% arbutin.

Application.Use water decoctions as a diuretic and with urolithiasis.

Rhizomes of male fern -Rhizomata Filicis maris

Plant.Male fern, or male thyroid, - Dryopteris filix mas (L.) Schott; the family of millipedes - Polypodiaceae, is sometimes considered as a representative of the thyroid family - Dryopteridaceae

The plant has two generations - sexual and asexual. A sexless diploid sporophyte is a perennial herb with a wintering rhizome. Rhizome is oblique, powerful, with many cord-like roots. The upper, growing, end of the rhizome carries a bunch of large leaves up to 1 m long, 20-25 cm wide. Non-bloomed leaves are cochlearly folded. Petiole of leaf up to 25 cm long is densely covered with rusty-brown scales; at its base it is very juicy and enlarged; when the leaf dies, this part of the petiole remains on the rhizome. The leaf plate is dark green, oblong-elliptical in outline, biconcoreally dissected, second-order segments carry denticles — they are blunt, not needle-like. On the lower surface of the leaf, brown soruses develop, covered by a kidney-shaped bract, under which oval sporangia containing brown spores are located on long legs. The spores, germinating, give the sexual generation - the gametophyte in the form of a small, green, lamellar, heart-shaped overgrowth, forming archegonia and anteridia. After fertilization, an asexual generation grows out of the zygote - sporophyte, the plant described above.

Male fern grows in moist shady forests, under cover of spruce or in spruce-deciduous stands - in the European part of Russia and the Baltic states; under the cover of beech, hornbeam and oak - in the Caucasus; under the Schrenk spruce - on the Tien Shan; under spruce and fir - in the Siberian taiga.
Chemical composition.The quality of rhizomes is primarily judged by the content of "raw filicin", meaning the sum of phloroglucides. The composition of crude filicin includes butyryl-phloroglucides of various complexity. The simplest compound is aspidinol containing one phloroglucinol ring. All other components of filicin are di- or trimeric phloroglucides, in which compounds close to aspidinol serve as monomers. Albaspidine is the dimer, phylic acid is the trimer; the more rings, the stronger the pharmacological effect.

The rhizomes of male fern, in addition to phloroglucides, contain starch, sucrose, tannins (7-8%), fatty oil (up to 6%), volatile fatty acids and their esters (butyric acid, etc.).

Medicinal raw materials- rhizomes, covered with numerous bases of leaf petioles, with the lower (dying) part removed and without roots, up to 25 cm long, in the thickest part up to 7 cm. The base of leaf petioles is 3-6 cm long, 6-11 mm thick, almost cylindrical forms, located tiled obliquely up. At the upper end of the rhizome are cochlearly folded leaf buds. The base of the petioles, especially the leaf buds, is densely covered with rusty brown membranous scales. Rhizomes and bases of petioles are dark brown outside, and light green in the section. At the same time, in the section, 6–9 centroxylem conducting bundles — “pillars” located in the periphery of the petiole with an incomplete ring — are clearly visible under the magnifying glass. The smell is weak, peculiar. The taste is initially sweet-astringent, then sharp, nauseous.

The content of raw filicin in the rhizomes of the male fern depends on the variety of fern 1, the area of \u200b\u200bits harvest, the vegetation phase. Harvested in the late summer and autumn. At this time, the rhizomes have the largest raw material mass. The content of crude filicin should be at least 1.8% (GF X). For medical purposes, raw materials that retain the light green color of rhizomes and petioles (in kink) are suitable. Shelf life of not more than a year in dry, dark rooms.

The impurities are the rhizomes of the female fern and ostrich operator.

In the female fern (Athyrium filix femina Roth), the rhizome is erect, the leaf petioles on the outside are almost black, triangular in shape with two large conducting bundles (“pillars”). In the ostrich operator -Matteucia struthiopteris (L.) Todar, the rhizome is erect, in the petioles there are 2 large "columns".

Ferns of the genus Dryopteris contain more or less phloroglucides. After studying some of them with large rhizomes, it turned out that the most promising were the subalpine fern (Dryorteris reados Fom.), Chartres fern, or needle (Dryorteriscarthususiana (Vill.) HP Fuchs \u003d D. spinulosa O. Kuntze), and the expanded fern , or Austrian (Dryorterisdilatata (HofFm.) A. Gray \u003d D. austriaca (Jacq.) Woyn. ex Schinz et Thell.). However, due to the abundance of thickets of male ferns, there is no need to harvest these types of fern yet.

Application.From the rhizomes of the male fern, freshly picked and dried, a thick extract is prepared, obtained by extraction with ether. The drug is an effective anthelmintic (tapeworms). List B.

Phenological glycosides is called a group of glycosides, the aglycon of which are phenols that provide a disinfectant effects on the respiratory tract, kidneys and urinary tract.   Phenolic compounds contain aromatic rings with a hydroxyl group. Compounds containing in the aromatic ring more than one hydroxyl group are called polyphenols. They are found in various parts of many plants - leaves, flowers (give them color and aroma), fruits.

The group of phenols with one aromatic ring includes simple phenols, phenolic acids, phenol alcohols, hydroxycinnamic acids. Phenologlicosides are found in bearberry and lingonberry leaves. Of the phenolic acids, gallic acid is often found and much less often - salicylic acid (violet tricolor). Phenolic acids and their glycosides are found in Rhodiola rosea.

Spread.

In nature, distributed quite widely. Found in families willow, lingonberry, saxifrage, chubby, etc..

Physiochemical properties.

Phenolic glycosides isolated in pure form are white crystalline substances, soluble in water, ethanol, insoluble in ether and chloroform. They are distinguished by optical activity and are capable of hydrolysis when heated with mineral acids. Free phenols and their glycosidic forms in the individual state are crystals of white or yellowish color, soluble in water, ethyl and methyl alcohols, ethyl acetate, as well as in aqueous solutions of alkalis and sodium acetate . All glycosides are optically active. Under the action of mineral acids and enzymes, phenological glycosides are able to break down into aglycone and carbohydrate.

Phenolic glycosides having free hydroxyls give reactions characteristic of phenolic compounds: with iron ammonium alum, with salts of heavy metals, with diazotized aromatic amines (sulfanilic acid or p-nitroaniline), etc.

Widely used for the detection and identification of phenological glycosides in plant materials, chromatography on paper and in a thin layer of sorbent. When treated with specific reagents and translucent in UV light, they appear as colored spots.

Spectrophotometric and photocolorimetric methods, and sometimes oxidimetric methods, are most often used to quantify phenols. For example, to determine the arbutin content in lingonberry and bearberry leaves according to GF X1, an iodometric method is used based on the oxidation of hydroquinone obtained after the extraction and hydrolysis of arbutin.

Methods of obtaining.

Extracted from plant materials with ethanol and methanol.

Qualitative reactions.

Phenolic glycosides with a free hydroxyl group give all the reactions characteristic of phenols (reaction with iron-ammonium alum, diazotization, etc.).

Application.

Phenolic glycosides containing arbutin have antimicrobial and diuretic activity. The solidosine glycoside contained in willow bark and underground organs of Rhodiola rosea has a stimulating and adaptogenic effect. Phenologlicosides of bearberry and lingonberry leaves in the body are broken down with the release of phenols with antimicrobial effects. And since these substances are formed in the kidneys, they disinfect the urinary tract. Phenological glycosides of Rhodiola rosea (Golden Root) relieve mental and physical fatigue, and tricolor violet substances have an expectorant effect.

The chemical classification of natural phenolic compounds is based on the biogenetic principle. In accordance with modern concepts of biosynthesis, phenols can be divided into several main groups, placing them in order of complexity of the molecular structure:

• 1. With 6 - connection with one benzene ring.

The simplest representative of phenolic compounds is phenol itself, which was found in the needles and cones of pine, as well as in the composition of essential oil of blackcurrant leaves and some other plants.

Among the simple monomeric phenols, di- and tri-atomic phenols are found:

In free form, these compounds are rare in plants, more often in the form of esters, glycosides, or are the structural unit of more complex compounds, including polymeric ones.

• 2. C 6 -C 1 - compounds. These include benzoic acids and their corresponding alcohols and aldehydes.

Oxybenzoic acids in plants are in bound form and are released after hydrolysis. An example is glucogallin found in rhubarb roots and eucalyptus leaves.

In many plants, a gallic acid dimer was discovered - m-digallic acid, which is a monomer of hydrolyzable tannins.

The ester bond formed by the phenolic hydroxyl of one hydroxybenzoic acid molecule and the carboxyl group of the other is called a depidic bond, and compounds containing such bonds are called depsidic bonds.

The group of C 6 -C 1 compounds includes lichen acids - specific phenolic compounds of lichens. The starting component in the formation of these acids is orselinic (6-methylresocyclic) acid.

• 3. C 6 -C 3 compounds (phenylpropane compounds). These include hydroxycinnamic acids, alcohols, aldehydes and coumarins.

Oxycinnamic acids are found in almost all plants, where they occur in the form of cis and trans isomers, which differ in physiological activity. When irradiated with UV light, the transforms transform into cis forms, which stimulate plant growth.

In plants, they are present in free form or in the form of glycosides and depsids with quinic or shikimic acids.

Oxycinnamic alcohols in free form do not accumulate, but are used as starting monomers in the lignin biosynthesis.

Coumarin - the lactone of the cis-form of coumaric acid belongs to this group.

Coumarin itself is not a phenolic compound, but plants contain its hydroxy derivatives.

5. C 6 -C 1 -C 6 compounds

These include benzophenone derivatives and xanthones.

• 6. C 6 -C 2 -C 6 connections

This group includes stilbenes, which are monomers of hydrolyzable tannins.

These compounds in the form of aglycons and glycosides were found in pine wood, eucalyptus, rhubarb roots, and in some types of legumes.

• 7. C 6 -C 3 -C 6 compounds, diphenylpropane derivatives

This is the most extensive group of phenolic compounds, which is ubiquitous in plants. They consist of two benzene rings connected by a three-carbon fragment, i.e. the six-membered oxygen-containing heterocycle resulting from the intramolecular condensation of most C 6 -C 3 -C 6 compounds is a derivative of pyran or g-pyrone

• 8. C 6 -C 3 -C 3 -C 6 dimeric compounds consisting of two phenylpropane units. This group includes lignans.
• 9. Compounds consisting of two or three condensed rings and containing hydroxyl and quinoid groups — naphthoquinones and anthraquinones.
• 10. Polymer compounds - tannins, lignans, etc .;
• 11. Compounds of a different structure — limitedly distributed chromons, or representing mixed phenols — flavolignans.

Phenolic compounds - substances of aromatic nature that contain one or more hydroxyl groups bonded to carbon atoms of the aromatic nucleus. Among products of secondary origin

Phenolic compounds are most common and characteristic of every plant and even every plant cell. The number of OH groups distinguishes monoatomic (for example, phenol itself), diatomic (pyrocatechol, resorcinol, hydroquinone) and polyatomic (pyrogallol, phloroglucinol, etc.) phenolic compounds.

Phenolic compounds can be in the form of monomers of dimers, oligomers and polymers; the classification of natural phenols is based on the biogenetic principle. In accordance with modern concepts of biosynthesis, they can be divided into several main groups:

• c6-series compounds are simple phenols;
• compounds C6 - C1 series - derivatives of benzoic acid (phenolic acids);
• compounds C6 - C2 series - phenol alcohols and phenylacetic acids;
• compounds C6 - C3 series - phenylpropane derivatives (hydroxycinnamic acids and alcohols, coumarins);
• compounds C6 - C3 - C6 series - flavonoids and isoflavonoids;
• compounds C6 - C3 - C3 - C6 series - lignans;
• derivatives of anthracene;
• polymer phenolic compounds - lignin, tannins, melanins.

Phenolic compounds are colorless or odor-colored crystals or amorphous substances, less often liquids, highly soluble in organic solvents (alcohol, ether, chloroform, ethyl acetate) or in water. Possessing acidic properties, they form salt-like products with alkalis - phenolates. The most important property of phenolic compounds is their ability to oxidize with the formation of quinone forms. Polyphenols are especially easily oxidized in an alkaline environment under the influence of atmospheric oxygen. Phenols are capable of producing colored complexes with heavy metal ions, which is characteristic of o-dioxo derivatives. Phenolic compounds react in combination with diazonium compounds. In this case, products with various colors are formed, which is often used in analytical practice. In addition to the general qualitative reactions common to all phenols, there are specific group reactions.

In plants, phenolic compounds play an important role in some intermediate stages of the respiration process. Participating in redox reactions, they serve as a link between the hydrogen of the respiratory substrate and atmospheric oxygen. It was found that some phenolic compounds play an important role in photosynthesis as cofactors. They are used by plants as energetic material for various life processes, they are regulators of growth, development and reproduction, while providing both stimulating and inhibitory effects. The antioxidant activity of many phenols is known, they are increasingly used in the food industry to stabilize fats.

Drugs based on phenolic compounds are used as antimicrobial, anti-inflammatory, choleretic, diuretic, antihypertensive, tonic, astringent and laxative.

The section comprehensively examines the laws and mechanisms of the biological action of phenolic compounds - an extensive group of organic substances that are ubiquitous in the plant world. Performing, along with proteins, nucleic acids, carbohydrates and other compounds, important functions in plant cells and tissues, phenols in food products, as well as various medicines of folk and modern medicine, enter the human body and have a noticeable effect on the work of various organs.

Designed for doctors, biologists and biochemists.

Phenols as medicines
  Acquaintance with the main manifestations of the physiological and pharmacodynamic activity of plant phenols convincingly showed that many of them have great prospects for use in the treatment and prevention of human diseases.

The main classes of organic compounds: proteins, nucleic acids, carbohydrates, fats, as well as mineral salts and trace elements necessary for life, are studied deeply and comprehensively.

Hundreds of thousands of pages of painstaking observations, countless experiments, the hopes and disappointments of thousands of researchers, arguments and discussions, mistakes and discoveries - these are what are hidden behind the laconic lines of biochemistry textbooks.

Proteins consisting of carbon, hydrogen, oxygen, nitrogen and sulfur, really perform the most important vital functions. Together with fat-like substances (lipids) they form biological membranes - the main structures of which the cells are built.

Protein-enzymes - the main engines, catalysts of metabolism - the most important life process.

Hormone proteins are a means of regulation and control in the machine of life. There are contractile proteins in the body, they work in the skeletal muscles, carry out the movement of the villi, the advancement of the food lump along the digestive tract; transport proteins, they carry many vital substances on the surface of their huge molecules; Antibody proteins are tiny defenders of our inner world from the encroachments of invisible enemies - bacteria and viruses.

There is no such form of life activity, such a biological process in which proteins would not play a primary role.

Nucleic acids, discovered for the first time in the composition of the cell nucleus, became known later than proteins, and their purpose in the body was fully established only in recent decades.

It is closely related to the role of proteins. Large molecules of nucleic acids (the largest of them consist of hundreds of thousands and even millions of carbon, hydrogen, oxygen and nitrogen atoms) store in their long strings, in the sequence of their atomic groups, hereditary memory of cells, information on the structure and production of proteins.

Carbohydrates and fats are much simpler, and their role in the body is less diverse.

Burning in the tissues in the process of slow biological oxidation, they give their energy to maintain the temperature of a living body, to carry out the biosynthesis of the organic compounds it needs. Fats and fat-like substances, together with proteins, are part of biological membranes, on the surface of which all the most important life processes occur. Carbohydrates (they are named so because they are built of carbon, hydrogen and oxygen, the last two elements being contained in them in the same ratio as in water, 2: 1), especially large polysaccharide molecules, play the role of an energy reserve (starch, glycogen).

Some of them, such as cellulose, are part of the membrane of plant cells, form fibers, and serve as an important supporting material in plant tissues.

The structure and vital role of vitamins, their very existence, became known only in the 20th century. The need for them is small, but they are necessary: \u200b\u200bif they are absent or lacking, a person becomes seriously ill and may even die from scurvy or pellagra, beriberi or rickets.

Entering the body with food, vitamins are necessarily present in body fluids unchanged or undergoing metabolic activation. For example, vitamin B1 is converted in the body to cocarboxylase (thiamine diphosphate), which has maximum activity.

Water-soluble vitamins B1 B2, B6, B12, PP, H, folic (Sun) and pantothenic (B3) acids play the role of coenzymes in the body. This is a kind of set of standard tools with which enzyme proteins perform their catalytic functions: cut or join molecules, transfer groups of atoms from molecules of one substance to another, accelerate the course of certain metabolic reactions.

Fat-soluble vitamins (A, D, E, K) are part of biological membranes - the main structural element of cells.

Membranes consist of a double layer of lipid (fat-like) molecules, a lipid "sea" in which protein particles "float" like icebergs. Membranes divide the cell into compartments that perform different functions; carry out the transfer of molecules, ions, electric charges, the main metabolic reactions. Fat-soluble vitamins stabilize the structure of membranes, protect them from oxidative degradation, and ensure the normal functioning of membrane enzymes.

Vitamin C stands apart; it is soluble in body fluids, but apparently does not possess coenzyme function.

Like fat-soluble vitamins, it has antioxidant activity, but is not part of the membranes, and it is washed in the body’s body fluids.

By the middle of the 20th century the time of great discoveries in the study of the chemical composition and structure of organic substances seemed to be over.

Biochemists rushed in pursuit of trace elements - substances that are present in living tissues in vanishingly small quantities, studying their role as cofactors of enzymatic catalysis, accelerators or inhibitors of metabolic reactions.

But there is, it turns out, a large and diverse class of organic compounds whose biological role has not yet been clarified. These are phenolic compounds. They will be discussed in the book.

There are many of these substances. They are found in every plant, in every cell of their body, in roots and leaves, in fruits and bark - wherever scientists look for them.

Several thousand phenols were isolated from plants, and this list continues to grow. Phenolic compounds account for up to 2-3% of the mass of organic matter of plants, and in some cases up to 10% and even more. Of course, such widespread and numerous organic substances must fulfill some important, necessary vital functions.

This is not to say that nothing is known about the role of plant phenolic compounds. Research in this area has been underway for more than 100 years, and a lot has been done in recent decades.

But very soon a strange circumstance became clear. Proteins and nucleic acids, carbohydrates and lipids are contained in the tissues of both plants and animals, are contained in approximately the same or similar proportions.

They are built according to a single plan, consist of the same starting elements (amino acids, nucleotides, fatty acids, monosaccharides). In the digestive tract of herbivores, plant food is split into such universal simple components that are part of their own organic compounds of these animals, and then carnivores. Moreover, it is possible to trace the fate of the same substances throughout the entire biological chain, from plants to animals and humans, and the functions of these substances in different parts of the chain in different species, classes and types of organisms turn out to be approximately the same and even similar.

The situation is completely different with phenolic compounds.

Their abundance and diversity in the plant world is sharply contrasted by the presence in the tissues of animals and humans of only a few representatives of the phenolic “kingdom”, which are also contained in very small, even insignificant, quantities. And despite the close similarities in the chemical structure of plant and animal phenols, no one has yet been able to completely confidently and reliably prove that there is the same continuity between them as between plant and animal proteins or carbohydrates.

Attempts to trace (using the method of labeled atoms or other modern scientific methods) the fate of phenolic compounds of plant foods in animals and humans have given the same result: the bulk of plant phenols burn in the body of animals to carbon dioxide and water, similar to how they behave carbohydrates or fats.

But is the role of carbohydrates purely energetic, or is any part of them still used in the biosynthesis of animal phenols?

There is no final answer to this question.

What is the function of plant phenols in the body of animals and humans, where they constantly come from food?

We will try to answer this question on the pages of the section.

The concept of phenolic compounds, distribution in the plant world, the role of phenolic compounds for plant life

Plants are able to synthesize and accumulate a huge number of phenolic compounds.

Phenols are aromatic compounds containing in their molecule a benzene core with one or more hydroxyl groups.

Compounds containing several aromatic rings with one or more hydroxyl groups are called polyphenols.

They are found in various parts of many plants - in integumentary tissues in fruits, seedlings, leaves, flowers, and - they are colored and aromatic by phenolic pigments - anthocyanins; most polyphenols are active metabolites of cell metabolism, play an important role in various physiological processes, such as photosynthesis, respiration, growth, plant resistance to infectious diseases, growth and reproduction; protect plants from pathogenic microorganisms and fungal diseases.

Spread.

Of the phenolic acids, gallic acid is often found and much less often - salicylic acid (violet tricolor). Phenolic acids and their glycosides are found in Rhodiola rosea.

The group of phenols with one aromatic ring include simple phenols, phenolic acids, phenolic alcohols, hydroxycinnamic acids.

Phenologlicosides are a group of glycosides whose aglycon is simple phenols that have a disinfecting effect on the respiratory tract, kidneys and urinary tract.

Phenologic glycosides are widespread in nature.

They are found in the families of willow, lingonberry, saxifrage, chubby, etc., are in bearberry and lingonberry leaves.

Natural phenols often exhibit high biological activity.

Drugs based on phenolic compounds are widely used as - antimicrobial, anti-inflammatory, hemostatic, choleretic, diuretic, antihypertensive, tonic, astringent and laxative.

Phenolic compounds are universal in the plant world.

They are characteristic of every plant and even every plant cell. Currently, more than two thousand natural phenolic compounds are known. The substances of this group account for up to 2-3% of the mass of organic matter of plants, and in some cases up to 10% or more.

Phenolic compounds are found as in lower; mushrooms, mosses, lichens, algae, and in higher spore (ferns, horsetails) and flowering plants. In higher plants - in leaves, flowers, fruits, underground organs.

The synthesis of phenolic compounds occurs only in plants, animals consume phenolic compounds in finished form and can only convert them

In plants, phenolic compounds play an important role.

They are mandatory participants in all metabolic processes: respiration, photosynthesis, glycolysis, phosphorylation.

Studies of the Russian scientist biochemist V. I. Palladin (1912) established and confirmed by modern studies that phenolic compounds are “respiratory chromogens”, i.e.

they participate in the process of cellular respiration.

Phenolic compounds, their characteristics and prevalence in nature

Phenolic compounds act as hydrogen carriers at the final stages of the respiration process, and then are oxidized again by specific oxidase enzymes.

2. Phenolic compounds are regulators of plant growth, development, and reproduction. At the same time, they have both a stimulating and inhibitory (retarding) effect.

Phenolic compounds are used by plants as an energy material, perform structural, supporting and protective functions (increases the resistance of plants to fungal diseases, have antibiotic and antiviral effects).

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Classification of simple phenolic compounds.

Depending on the nature of the substituents in the benzene ring, phenological glycosides can be divided into 3 groups:

1st group: C6 - rows

1) monohydric phenols

simple phenols (monophenols) - monohydroxy derivatives - are rare in plants.

Phenol itself was found in the needles and cones of Pinus silvestris, essential oils of the leaves of Nicotiana tabacum, Ribes nigrum, lichens.

2) Dihydroxy derivatives - diatomic phenols (diphenols)

a) Pyrocatechol (1,2-dioxibenzene) is found in ephedra leaves, onion scales, and grapefruit.

b) Of the dioxibenzenes, the most common hydroquinone (1,4-dioxibenzene).

Its glycoside is arbutin, contained in the representatives of the families: Ericaceae (bearberry leaves), Vacciniaceae (lingonberries), Saxifragaceae (incense).

Along with arbutin, methylarbutin is present in these plants.

Its aglycon is methylhydroquinone

Arbutin methylarbutin

c) Resorcinol (1,3-dioxibenzene) (or m-dioxibenzene) is found in various natural resins, tannins.

Triatomic phenols (triphenols).

The representative of trioxybenzenes is phloroglucinol (1,3,5-trioxybenzene), in its free form it is found in the cones of sequoia and onion scales, and in the form of florin glycoside in the pericarp of fruits of different types of citruses.

More complex compounds are phloroglucides (phloroglucin glycosides), they can contain one ring of phloroglucin (aspidinol) or they are dimers or trimers (flavaspidic acid and phyloxy acid).

Significant amounts of phloroglucides accumulate in the rhizomes of the male fern.

aspidinol

1) C6 - C1 - series - Phenolcarboxylic acids

Phenolic acids   widely distributed in plants, but are not the main biologically active substances in them; these are typical concomitant substances involved in the therapeutic effect of total drugs.

Widely distributed in plants of the families: legumes, sumacs, violets, lingonberries.

Widespread n-hydroxybenzoic acid

For example, catechol acid is characteristic of angiosperms.

Gallic acid can accumulate in significant amounts (in bearberry leaves)

Salicylic acid is relatively rare, salicylic acid glycoside aglycon contains a carboxyl group:

Its methyl esters are part of the essential oils of plants of the families of violet, birch, willow (field violet grass, raspberry fruit, has anti-inflammatory and antipyretic effects).

C6-C2 - rows - Phenol alcohols and their glycosides are contained in Rhodiola rosea

Salidroside and salicin.

The aglycones of these glycosides are 4-hydroxyphenylethanol and 2-hydroxyphenylmethanol (salicylic alcohol).

Along with phenolic hydroxyls, these aglycones have alcoholic hydroxyl groups, and their glycosidation can be in phenolic and alcoholic groups:

Salicylic alcohol

Salicin Salidroside

(2-hydroxyphenylmethanol)

Salicin received from the bark of willow the French scientist Leroux in 1828.

I. General characteristics of simple phenolic compounds

A lot of it is in the leaves and shoots of bearberry, lingonberry, pear, and incense. Often in plants it is accompanied by methylarbutin.

Salidroside was first isolated in 1926 from willow bark, and was later found in the underground organs of Rhodiola rosea.

C6 - C3 - rows - hydroxycinnamic acids

The most common caffeic acid and its compounds:

Cinnamic acid n-coumaric acid caffeic acid

Rosemary to-chlorogenic to-that

Chlorogenic acid is found in green coffee beans (6%), tobacco leaves (8%); rosmarinic acid was first found in rosemary officinalis, but is also found in other representatives of the labiate.

The precursor of hydroxycinnamic acids is phenylalanine.

Oxycinnamic acids have antimicrobial and antifungal activity, exhibit antibiotic properties.

Oxycinnamic acids and their esters have a directed effect on the function of the kidneys, liver, and urinary tract. Contained in the grass are horsetail, St. John's wort, tansy flowers, immortelle sand.

Physical properties

Simple phenolic compounds are colorless, rarely slightly colored, crystalline substances with a certain melting point, optically active. They have a specific smell, sometimes aromatic (thymol, carvacrol). In plants, they are more often found in the form of glycosides, which are readily soluble in water, alcohol, acetone; insoluble in ether, chloroform. Aglycons are slightly soluble in water, but readily soluble in ether, benzene, chloroform and ethyl acetate. Simple phenols have characteristic absorption spectra in the UV and visible regions of the spectrum.

Phenolic acids - crystalline substances, soluble in alcohol, ethyl acetate, ether, aqueous solutions of sodium bicarbonate and acetate.

Gossipol is a fine crystalline powder from light yellow to dark yellow in color with a greenish tint, practically insoluble in water, slightly soluble in alcohol, well soluble in lipid phases.

Chemical properties.

The chemical properties of simple phenolic compounds are due to the presence of:

· Aromatic ring, phenolic hydroxyl, carboxyl group;

Glycosidic bond.

Chemical reactions are characteristic of phenolic compounds:

1. Hydrolysis reaction(due to glycosidic bond). Phenolic glycosides are easily hydrolyzed by acids, alkalis or enzymes to aglycon and sugars.

2. Oxidation reaction.Phenolic glycosides are easily oxidized, especially in an alkaline environment (even with atmospheric oxygen), forming quinoid compounds.

3. The reaction of salt formation.Phenolic compounds, possessing acidic properties, form water-soluble phenolates with alkalis.

4. Complexation reactions.Phenolic compounds form complexes of various colors with metal ions (iron, lead, magnesium, aluminum, molybdenum, copper, nickel).

5. The azo coupling reaction with diazonium salts.Phenolic compounds with diazonium salts form azo dyes from orange to cherry red.

6. The reaction of the formation of esters (depsidov).Depsids form phenolic acids (digallic acid, trigallic acid).

Quality assessment of raw materials containing simple phenolic compounds. Analysis methods

Qualitative and quantitative analysis of raw materials is based on physical and chemical properties.

Qualitative analysis.

Phenolic compounds are extracted from plant materials with water. Aqueous extracts are purified from the accompanying substances, precipitating them with a solution of lead acetate. With purified extraction, quality reactions are performed.

Phenological glycosides having free phenolic hydroxyl give all reactions characteristic of phenols (with salts of iron, aluminum, molybdenum, etc.).

Specific reactions (GF XI):

1. on arbutin (raw lingonberry and bearberry):

a) with crystalline iron ferrous sulfate.The reaction is based on the preparation of a complex that changes color from lilac to dark violet, with the further formation of a dark violet precipitate.

b) with a 10% solution of sodium phosphoromolybdenum acid in hydrochloric acid.The reaction is based on the formation of a complex compound of blue color.

2. for salidroside (raw material of Rhodiola rosea):

a) azo coupling reaction with diazotized sodium sulfacylwith the formation of azo dye cherry red.

Chromatographic study:

Use various types of chromatography (paper, thin layer, etc.). Chromatographic analysis usually uses solvent systems:

N-butanol-acetic acid-water (BUV 4: 1: 2; 4: 1: 5);

Chloroform-methanol-water (26: 14: 3);

· 15% acetic acid.

Chromatographic study of alcohol extraction from Rhodiola rosea.

Thin layer chromatography is used. The sample is based on separation in a thin layer of silica gel (Silufol plate) of methanol extraction from raw materials in a solvent system of chloroform-methanol-water (26: 14: 3), followed by the development of a chromatogram of diazotized sodium sulfacyl. The salidroside stain with Rf \u003d 0.42 turns reddish.

Quantitation.

For the quantitative determination of phenological glycosides in medicinal plant materials, various methods are used: gravimetric, titrimetric and physicochemical.

1. Gravimetric methoddetermine the content of phloroglucides in the rhizomes of male fern. The method is based on the extraction of phloroglucides from raw materials with diethyl ether in a Soxhlet apparatus. The extract is purified, ether is distilled off, the resulting dry residue is dried and adjusted to constant weight. In terms of absolutely dry raw materials, the content of phloroglucides should be at least 1.8%.

2. Titrimetric iodometric methodused to determine the arbutin content in raw lingonberry and bearberry. The method is based on the oxidation of aglycone hydroquinone to quinone with a 0.1 M solution of iodine in an acidic medium and in the presence of sodium bicarbonate after obtaining purified aqueous extraction and carrying out acid hydrolysis of arbutin. The hydrolysis is carried out with concentrated sulfuric acid in the presence of zinc dust, so that the released free hydrogen prevents the inherent oxidation of hydroquinone. A starch solution is used as an indicator.

I 2 (g) + 2Na 2 S 2 O 3 → 2NaI + Na 2 S 4 O 6

3. Spectrophotometric methodused to determine the content of salidroside in the raw material of Rhodiola rosea. The method is based on the ability of colored azo dyes to absorb monochromatic light at a wavelength of 486 nm. The optical density of the colored solution obtained by the reaction of salidroside with diazotized sodium sulfacyl is determined using a spectrophotometer. The salidroside content is calculated taking into account the specific absorption rate of GSO salidroside E 1% 1cm \u003d 253.