Biotechnology for Medicine (continued-1)

The use of natural diversity for therapeutic purposes is not limited only to fungi and actinomycetes that produce antibiotics. In particular, plants are distinguished by an amazing variety of synthetic processes, the end products of which are represented by compounds of a very different chemical structure. In modern medicine, fatty acids, oils, polysaccharides of plant origin, as well as surprisingly diverse secondary metabolites are used. Secondary metabolism, in contrast to the primary metabolism common to all organisms, is characterized by taxonomic originality. Secondary metabolism of plants is a feature of differentiated plant cells and tissues, it is inherent only in specialized organs, is confined to certain phases of the life cycle. The main classes of secondary metabolites include alkaloids, isoprenoids and phenolic compounds. Cyanogenic glycosides, polyketides, and vitamins are also synthesized in plants. Of the 30 known vitamins, about 20 enter the human body with plant foods. Some of the listed classes of compounds, as well as the plants from which they are isolated, are presented in the table

Alkaloids. To date, about 10 thousand alkaloids are known, and they have high pharmacological activity. The content of alkaloids in plant raw materials usually does not exceed several percent, but in the bark of the cinchona tree their amount reaches 15-20%. Alkaloids can be concentrated in various organs and tissues. At the same time, they often accumulate in the wrong tissues where they are synthesized. For example, nicotine is synthesized in the roots of tobacco, and stored in the leaves. Among the most famous alkaloids are morphine, codeine, papaverine, which were isolated from the boxes of sleeping pills (Papaver somniferum). Alkaloids of belladonna belladonna (Atropa belladonna), which is otherwise called "sleepy stupor", are part of many medications, such as besalol, bellalgin, bellataminal, solutan. Alkaloids from periwinkle (Catharanthus roseus) – vinblastine and vincristine - have become widespread in modern oncology, and reserpine and aimalin from the roots of Rauvolfia (Rauvolfia serpentina) are used as psychotropic drugs and to lower blood pressure.

Isoprenoids. According to the number of isolated compounds, isoprenoids surpass all other classes of secondary metabolites (there are more than 23 thousand of them), but they are inferior to alkaloids in pharmacological activity. Compounds of different structures are combined into this group. Some of them cannot be replaced with synthetic preparations, for example, taxols isolated from the bark of a yew tree. They are extremely active cytostatics, acting on cancer cells in very small doses. Currently, oncology has high hopes for them.

The most important group of isoprenoids are cardiac glycosides, or cardenolides. For example, about 50 cardenolides, including digitoxin, have been isolated from two species of purple foxglove (Digitalis purpurea) and woolly foxglove (D. lanata). The natural glycoside k-strophanthoside, which is an indispensable tool for emergency care, has become widely used in medical practice: it acts on the heart 1-3 minutes after intravenous administration. This drug is isolated from the seeds of the vine Strophanthus kombe, which grows in the tropical forests of Africa, where the local population used the juice of this plant as poison for arrows. Cardiac glycosides from May lily of the valley (Cjnvallaria majalis) are more active than other cardiac glycosides (for example, digitoxin).

Other groups of isoprenoids important for medicine are triterpene glycosides, or saponins. Most representatives of this group have high biological activity, which determines their therapeutic effect and the use of such well-known biostimulants as ginseng, aralia, licorice.

Steroid glycosides differ in biological activity from triterpenes. For modern medicine, this is the raw material for the synthesis of many hormones and contraceptives. Since the 40s of the last century, glycoside diosgenin from the rhizomes of various types of lianas from the genus Dioscorea has been mainly used to obtain steroid raw materials. Currently, more than 50% of all steroid medicines are obtained from it. Recent studies have revealed other properties of compounds of this group that are important for medicine.

Phenolic compounds. The most numerous and widespread group of phenolic compounds in plants are flavonoids. They accumulate in licorice roots (Glycyrrhiza glabra), motherwort grass (Leonurus cordiaca), immortelle flowers (Helichryzum arenarium). Flavonoids have a wide spectrum of pharmacological action. They have choleretic, bactericidal, antispasmodic, cardiotonic effects, reduce the fragility and permeability of blood vessels (for example, rutin), are able to bind and remove radionuclides from the body, they also have an anti-cancer effect. 

The amazing biosynthetic capabilities of plants are still far from being revealed. Of the 250 thousand species living on Earth, no more than 15% were examined, and cell cultures were obtained only for some medicinal plants. Thus, cell cultures of ginseng and dioscorea are the basis of the biotechnological process of obtaining triterpene and steroid glycosides. Great hopes are pinned on the introduction of these new technologies, since many rare or non-growing plants in our climatic conditions can be used in the form of callus or suspension crops. Unfortunately, the technogenic nature of civilization on our planet causes irreparable damage to wild flora. Not only the Earth's biosphere - the human habitat - is changing, but also huge unexplored storerooms of health and longevity are being destroyed.