Rauwolfia other snake – Rauwolfia serpentina Benth.
This type of rauwolfia grows in the Himalayas, in India, Burma, and also in Indonesia; cultivated in India. This is an evergreen shrub, the leaves are whorled in 3-4, dense, glabrous, oval, slightly pointed. Flowers in dense umbellate inflorescences, corolla pink, tubular, 5-lobed, the lobes overlap one another. The fruits are red, consist of 2 juicy drupes, fused to the middle.
Collect the root (Radix Rauwolfiae serpentinae); it is pivotal, 2-3 cm long, curved, with large lateral roots. The surface is brown, the break is light, non-fibrous, the bark is narrow, the wood occupies the thickness of the cut. The taste of the root is bitter, there is no smell.
The root contains more than 25 alkaloids, the sum of which is traditionally 1-2%. All rauwolfia alkaloids are derivatives of yohimbine. Among them, there are groups of alkaloids such as reserpine, aymaline, serpentine, etc.
The alkaloids reserpine, aymaline and some total alkaloid products (for example, raunatin) are used. Reserpine refers to drugs that calm the central nervous system – tranquilizers. Prescribed for hypertension, as a sleeping pill, for mental illness (psychoneurosis).
Aymalin does not have a tranquilizing effect and has little effect on blood pressure in hypertensive disease. Due to its normalizing effect on the disturbed rhythm of cardiac activity, aymalin has found wide application as an effective antiarrhythmic agent.
In view of the great need for reserpine and aymaline, R. serpentina Benth. taken in culture in India; in addition, additional sources and substitutes have been identified. In India, another species is used – Rauwolfia canescens L. – grayish rauwolfia. In total, up to 150 species of the genus Rauwolfia have been identified in the world flora, found in the tropics and subtropics of Southeast Asia, Africa and South America, which are now all being studied. In Africa (Congo), the extraction of the root of Rauwolfia vomitoria Afz – rauwolfia emetic, whose alkaloids have a similar effect, has been established.
The plant contains indole alkaloids.
PLANTS CONTAINING ALKALOIDS
Alkaloids are called natural nitrogen-containing compounds of the main nature, formed in plants. Groups of proteinogenic amines (for example, tyramine) and betaines (stakhidrin, trigonelline, etc.) adjoin the alkaloids, which are considered as transitional compounds from the simplest nitrogen-containing compounds (methylamine, trimethylamines, etc.) to the alkaloids proper.
Of natural pharmacologically active substances, alkaloids are the main group from which modern medicine draws the largest number of highly effective drugs.
According to world literature, by the end of the past decade, the number of alkaloids isolated from the higher plants of the Earth’s flora exceeded 5000. According to modern concepts, alkaloid-bearing plants make up 10% of the entire world flora. The families Equisetaceae, Lycopodiaceae, Ephedraceae, Liliaceae, Amaryllidaceae, Dioscoreaceae, Chenopodiaceae, Nymphaeaceae, Ranunculaceae, Berberidaceae, Menispermaceae, Papaveraceae, Fabaceae, Rutaceae, Cactaceae, Punicaceae contain the largest number of alkaloid-bearing genera and species. Loganiaceae, Apocynaceae, Borraginaceae, Solanaceae, Rubiaceae.
Usually plants that are phylogenetically close contain alkaloids that are very similar in structure, thus forming a natural group of genera. For example, plants of the genera Atropa, Datura, Hyoscyamys, Scopolia, Physochlaina, Duboisia. Mandragora (all from the same Solananeae family) contain a well-defined group of tropane alkaloids. This far-reaching pattern, however, has exceptions that have not yet been explained. So, for example, caffeine is found in plants that are not systematically related to each other: tea (Theaceae), coffee (Rubiaceae), cocoa (Sterculiaceae), mate (Aquifoliaceae), guarana (Sapindaceae), erodium (Geraniaceae). Along with this, there are cases when their 2 very close systematically species, one is rich in alkaloids, and the other either does not contain them at all, or contains alkaloids of a different structure.
Alkaloids can be found throughout the plant, or they can be formed and accumulated only in one or more specific organs. The plant traditionally contains not one, but several alkaloids. In individual plants, there may be 20 or more of them (cinchona, hypnotic poppy, etc.), and they may be similar in structure or belong to different chemical groups. In the sum of alkaloids, 1–3 traditionally predominate quantitatively (the main alkaloids). In plants, alkaloids are dissolved in the cell sap of the main parenchyma, phloem, and other tissues in the form of salts, mainly organic acids (malic, succinic, citric, oxalic, fumaric, quinic, etc.); of mineral acids, phosphoric acid is more often involved.
The quantitative content of alkaloids is, in principle, a species characteristic, and it varies over a very wide range. For example, in black henbane they are only 0.05-0.1%, and up to 15% accumulate in the cinchona bark. In the process of ontogenetic development of plants, their alkaloid content undergoes quantitative and sometimes qualitative changes, and each species has its own regularities.
The content of alkaloids in plants is influenced by their geographical location and various factors (air and soil temperature, precipitation, duration and intensity of sunlight, shading, height above sea level, etc.), as well as human impact in the case of transferring the plant to cultivation or its acclimatization. The largest number of alkaloid-bearing species, moreover, with a high content of alkaloids, is common in subtropical and tropical states with a humid climate. Alkaloids of different structure are confined to certain latitudes, and in connection with this, their pharmacological activity changes.
There is no consensus on the biological role and causes of the formation of alkaloids in plants. The main hypotheses proposed at different times interpret alkaloids as: 1) waste products of the vital activity of a plant organism; 2) spare substances; 3) protective substances; 4) active substances necessary for biosynthesis. The latter hypothesis is currently considered by most scientists to be the most general one, which, however, does not exclude other biological functions of alkaloids.
The exceptional diversity in the structure of alkaloid molecules does not allow us to imagine a single way of their formation in plants. Their biosynthesis proceeds according to specific schemes with the most complex chemical transformations (ring opening and closing, oxidation, deamination, ring condensation, etc.) through many intermediate products. Some alkaloids begin biogenesis from amino acids, others from acetic acid (in other words, from carbohydrates).
The modern classification of alkaloids is based on the nature of the heterocycles included in their molecules, with the release into a separate group of alkaloids with an aliphatic structure and with nitrogen in the side chain.
1. Alkaloids with an aliphatic structure or with nitrogen in the side chain;
2. Pyrrolizidine alkaloids.
3. Piperidine and pyridine alkaloids.
4. Alkaloids with condensed and pyrrolidone and piperidine rings.
5. Quinoline alkaloids.
6. Quinazoline alkaloids.
7. Isoquinoline alkaloids.
8. Indole alkaloids.
9. Alkaloid of the imidazole group.
10. Purine alkaloids.
11. Diterpene alkaloids.
12. Steroid alkaloids (glycoalkaloids).
13. Alkaloids of unknown structure.
In conclusion of this brief review, it should be pointed out that most alkaloids are highly active substances with selective pharmacological action. The selectivity of the action of alkaloids determines their widespread use for medicinal purposes. The main forms are extraction products (tinctures, extracts, novogalenic preparations, etc.) and pure alkaloids isolated from plants, converted into soluble salts of certain inorganic and organic acids.