Chinese tea

Tea Chinese – Thea sinensis L., syn Camellia sinensis O. Htze.



The homeland of the tea bush is Southwestern China and the adjacent regions of Vietnam and Burma.

The birthplace of the tea drink is the Chinese province of Yunnan, where it has been known since time immemorial. In the middle of the IV century. The Chinese introduced the tea bush into cultivation. Tea was brought to Europe at the beginning of the 16th century. the Portuguese; tea has been known in Russia since 1567. In the past, China was the leader in tea production on the globe. At present, the largest areas of the tea bush are in India, followed by Sri Lanka, Indonesia, Vietnam, Africa, Pakistan, Argentina, Brazil, and others. The USSR is also among the major tea producers.

Evergreen shrub or tree up to 10 m tall. On industrial plantations, the tea bush is not allowed to grow above 1 m – it is systematically cut off, giving it a hemispherical shape. Pruning promotes an abundance of branches and therefore leaves. The leaves are alternate, oval, narrowed at the top, sharp-toothed along the edge, teeth with gradually blackening glands. Young, freshly blossomed leaves are covered with silvery “fluff” (in Chinese “bai-ho”, – hence “baih tea”, i.e. tea from young leaves). Mature leaves 6-30 cm long, leathery, light green below, only slightly pubescent. The flowers are white or pink, fragrant, 2-4 in the axils of the leaves; stamens are numerous (more than 200), fused with the bases of the petals, so the corolla falls along with the stamens. The fruit is a 3-5-leaf box.

The species T. sinensis L. is differentiated into a number of varieties, numerous populations of which are confined to certain culture zones: var. bohea (L.) DC. cultivated in Japan, South Korea, East China; var. cantonensis (Lour) Choisy – Cantonese tea (China), var. assamica (Mast.) Choisy – Assam tea (India), var. viridis (L.) DC. – green tea (China).

Numerous varieties of tea (Chinese, Japanese, Indian, Ceylon, Georgian, etc.) are mostly complex mixtures. Collect (manually or with the help of machines) only young shoots – flushes with the first three leaves; the fourth leaf with the axillary bud remains on the branch and a new shoot develops from the bud. A freshly picked tea leaf is very different in appearance and taste from the finished tea. Its taste is bitter, the smell is grassy, ​​which persists after drying under normal conditions. To obtain the main variety of tea – the so-called black – flushes at tea factories undergo complex processing, consisting of withering, leaf twisting, fermentation, drying, sorting of tea mass and blending according to strict recipes. The most important stage is fermentation, during which the aroma, taste and other properties of tea are formed. Black slab tea is obtained from the chips and crumbs by pressing. Green tea is not fermented; enzymes are destroyed by heat.

The leaves of the tea bush contain 1.5-3.5% caffeine, 20-24% tannins (“tea tannin”), flavonoids, traces of essential oil and vitamins C, B 6 B 2 , nicotinic and pantothenic acids.

Tannins in tea are peculiar. Their main part is a complex mixture of catechins and their derivatives.


In the process of fermentation, the condensation of 2 molecules of catechins occurs with the formation of a dimeric compound.


Dimercatechins are typical “tea” tannins, responsible for the slightly astringent taste and golden-red color of the drink. Typical flavonoid compounds are represented in tea by flavonol glycosides (quarcetin and kaempferol). Catechins and their dimers, as well as flavonol glycosides, have capillary-strengthening properties. The combination of other vitamins and caffeine with them provides the tea-drink with the properties of a valuable drug and antidote for poisoning. Pruning bushes, large leaves and partially tea screenings are the raw materials for obtaining caffeine. Caffeine preparations are used to excite the central nervous system and heart muscle. Vitamin P is also produced from tea waste. Tea tannins serve as raw materials for products such as thealbin (a complex compound with casein) used as an astringent.

The plant contains purine alkaloids.



Purine is a fused system of pyrimidine and imidazole rings. Purine alkaloids in nature are represented by methyl derivatives of the oxygen derivative of purine – xanthine (2, 6-dioxipurine). The main ones are caffeine, theobromine and theophylline.



Purine is a fused system of pyrimidine and imidazole rings. Purine alkaloids in nature are represented by methyl derivatives of the oxygen derivative of purine – xanthine (2, 6-dioxipurine). The main ones are caffeine, theobromine and theophylline.


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.

Leave a Comment

Your email address will not be published. Required fields are marked *