pink catharanthus

Catharanthus pink – Catharanthus roseus (L.) G. Don., syn. Vinca rosea L.

 

 

Wildly grows in Indonesia on about. Java. In Africa, in the tropical zone, it is tested in culture.

Pink catharanthus is an upright or creeping perennial evergreen shrub, reaching 30-60 cm in height in its homeland (Java Island). Stem glabrous (slightly or strongly pubescent in some forms), almost cylindrical. The leaves are opposite, dark green, shiny, up to 12 cm long, lobed, oblong-oval, short-petiolate, with pinnate, pronounced venation, slightly wavy along the edge. Flowers regular, axillary, collected 2-4 in dichasium. The calyx is separate-leaved, green. Corolla raspberry-pink, cleft-petaled, regular. The fruit is a crescent-shaped fractional dark brown two-leaf, opening and falling off when ripe.

In all parts of the plant there are several dozen indole alkaloids, of which two groups of bases are of practical interest. One of them is close in its therapeutic effect to rauwolfia alkaloids (serpentine, aimalicin, lochnerin, etc.). Serpentine has a dihydrogenated C ring and an oxygen bridge in the E ring. Another group of bases is represented by dimeric indole alkaloids vinblastine, vincristine, leurosine and other compounds close to them,

 

According to the mechanism of biological action at the cellular level, these alkaloids with antitumor activity are classified as mitotic poisons. They stop the reproduction of cells, affect the structure that ensures the divergence of chromosomes. Another effect of alkaloids is to induce significant changes in the properties of the cell plane.

The vinblastine molecule is composed of 2 alkaloids – catharantine and vindoline. None of the monomeric components has either antitumor or antimitotic activity. This also applies to other dimeric vinca alkaloids.

Katarantus rosea has long been used in Indian folk medicine in the treatment of diabetes and as an antispasmodic.

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.      Алкалоиды с конденсированным и пирролидоновым и пипе- ридиновым циклами.

5.      Хинолиновые алкалоиды.

6.      Хиназолиновые алкалоиды.

7.      Изохинолиновые алкалоиды.

8.      Индольные алкалоиды.

9.      Алкалоида группы имидазола.

10.    Пуриновые алкалоиды.

11.    Дитерпеновые алкалоиды.

12.    Стероидные алкалоиды (гликоалкалоиды).

13.    Алкалоиды неустановленного строения.

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.

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