Chemicals saponins (also glycosides, saponisides or heterosides) are derivatives of triterpenoids and steroids. They have superficial and hemolytic activity, and are also toxic to cold-blooded species of animals. Saponins are divided into triterpene and steroid. They are found in the stems, leaves, flowers, roots and fruits of plants. These substances are composed of carbohydrates and aglycon.
Description and characteristic
Any saponin, the properties of which have several characteristic features, has a noticeable effect on biological organisms. This substance causes erythrocyte hemolysis and forms cholesterol (because of this, the erythrocyte membrane loses its semipermeability). The action of saponins leads to the entry of hemoglobin into the blood. Due to this effect, the work of the gills is disrupted in cold-blooded animals.
Many organisms die from the poison secreted by saponins. What it is? These compounds are amorphous or crystalline hygroscopic substances of a yellowish tint (or colorless). Saponins are characterized by a high melting and decomposition temperature. They are able to lower surface tension, which is why when shaken, their aqueous solutions form an abundant stable foam. Siponins are insoluble in chloroform, benzene and diethyl ether. Otherwise, the situation is with water, ethanol and methanol. In these hydrophilic solvents, saponins are soluble in the case of a high content of monosaccharides in their molecules.
Examples of Saponin in Nature
Not one plant family contains saponins. In total, scientists have about 40 similar species groups. Cells of such plants contain dissolved saponins. What it is? Most often, this is part of the chemical composition of underground plants. Triterpene saponins are characteristic for cloves, aralia, legumes, cyanosis, istodata, chestnut, rosaceae, etc. These are such common plants as licorice, ginseng, or, for example, aralia.
Steroidal saponins are part of plants belonging to the families of Liliaceae, Norica, Agave, Dioscorea, etc. This group includes sarsaparil, digitalis and dioscorea.
Interestingly, representatives of the plant world secrete saponins for their own protection against pathogens. So, glycosides stimulate their growth rate, resistance to stress and improve germination. By means of saponin, the composition of carotenoid pigments involved in photosynthesis changes. The substance can be produced in leaves, from where it is transported throughout the rest of the plant. A useful compound accumulates in special cells of the stems and epidermis. In the end, it gets into the rhizome, responsible for vegetative propagation. Saponins are produced at an increased rate in case of damage to plant tissue.
Hydrolysis and monosaccharide content
Biological saponins in plants are hydrolyzed by acids. They can form molecular complexes with lipids, sterols, proteins and phenolic compounds. Saponins (more precisely, their carbohydrate part) contain from 1 to 11 monosaccharides. Depending on this amount, the substance belongs to a certain type: oligosides, pentosides, triosides, biosides, monosides.
Most often they contain substances such as D-xylose, D-glucose, D-galactose, L-arabinose, L-rhamnose, etc. Similar elements include saponins. What it is? Monosaccharides are organic compounds that form carbon chains, which can be branched or linear. Steroid types of saponins consist of 1-5 such elements, while triterpene ones can number 10 or even more.
Extraction of saponins
Obtaining saponins from the source of natural raw materials is carried out in several stages. First, extraction occurs (transfer of components from a solid to a liquid using a solvent). Then the resulting substance is purified and separated.
For extraction, polar solvents are used - ethanol and methanol with various concentrations. A sodium chloride solution is also used. In some cases, the raw materials are treated with ether and carbon before extraction. Without this procedure, it is impossible to destroy complex-soluble complexes, including saponins, proteins, sterols and phenolic compounds.
Cleaning
The method of purification of the obtained saponins depends on their structure. For example, polar species are poorly soluble in methyl and ethyl alcohol, and when cooled or added ethanol form a characteristic precipitate. The situation is different with glycosides. They precipitate after dilution with water of alcoholic extracts, and also poorly soluble in the water itself. Alkali is required to clean triterpene saponins. They are also affected by acetone, diethyl ether, ethyl acetate, isoamyl and butyl alcohols.
Other purification methods are based on the property of saponins to create water-insoluble salts with lead acetate or barium hydroxide. After obtaining such complexes, they are decomposed. Similar methods are necessary in order to form the purest saponins. What it is? These are the most high-quality and impurity-free components with a uniform composition.
Chromatographic separation
Any plant matter (e.g. flavonoids, saponins, etc.) requires careful processing. When cleaning them, in addition to the methods already described, chromatographic separation is often used today. In this case, solvents such as acetic acid, n-butanol, chloroform, aqueous ammonia, n-propyl alcohol, methanol, etc. are used.
Following preliminary chromatographic separation, treatment with acid reagents â phosphoric molybdenum acid, antimony pentachloride, etc., begins. As a result, saponins form polyenes â conjugated unsaturated compounds. They can be colored red-violet or pink (depending on the structure of the substance).
Application
Saponins are used for a variety of purposes. For example, they are added to a foaming agent in fire extinguishers (due to the fact that these substances form a rich foam). Saponins are also included in suspensions and emulsions, thereby stabilizing these dispersed systems. The substances of this group are distinguished by emulsifying properties, which makes them a useful component of soap.
Saponins are used in the preparation of certain drinks (for example, beer), as well as confectionery (halva). They are produced as dietary and nutritional supplements. They are also used in medical devices (sedatives, tonic, expectorant, vaccines, etc.). Despite its therapeutic benefits, saponins require caution when consumed due to their toxicity.
Use in pharmacology
Licorice saponins have long been known for their anti-allergic and anti-inflammatory effects. Preparations based on them can be a powder, syrup or extract. Licorice root is the basis of pills. It is added to improve the taste of medicines and drugs. Licorice is used in case of viral infections of the skin and genitals, as well as with lichen.
The most useful part of saponins from the point of view of pharmacology is glycyrrhetinic and glycyrrhizic acids. Based on them, drugs are produced that help in the fight against bronchial asthma. Another useful component is the flavonoid. These compounds are part of flacarbin and lycirithone, which have antiulcer, antisecretory, antispasmodic and anti-inflammatory effects. These drugs are used for gastric and duodenal ulcers or gastritis.
The beneficial effect of ginseng has been known in the East for several millennia, where this plant has become a popular drug and is symbolically called the "root of life." In China and Korea, it is used in cooking. Ginseng roots have a tonic and stimulating effect, they are used as an adaptogen. Means based on these reagents are used in the treatment of adrenal glands. The concentration of saponins in ginseng reaches a maximum when the plant reaches six years of age.
Effects on the human body
Like alkaloids, saponins have an effect on human health. If it enters the oral cavity or on the mucous membranes of the nose and eyes, they cause irritation. Enhanced secretion of the glands begins, which helps get rid of sputum and helps the bronchi. However, the concentration of saponins for the human body can be excessive. In this case, irritation of the intestines and stomach occurs. The toxic effects of these substances lead to vomiting, nausea, dizziness and diarrhea.
Saponins are useful as substances that make other drugs more quickly absorbed into the human body. Their effect depends on the particular plant. In addition to the effects already mentioned, they can have an antiulcer, mild laxative, adaptogenic, corticotropic and diuretic effect.
Raw materials
One of the most frequent sources of raw materials for the isolation of saponins is Manchu aralia. This is a small and fast-growing tree with a height of 3 to 6 meters. It has a superficial root system and looks like a palm tree. The plant is distributed in the Far East of Russia, including the Khabarovsk Territory, Primorsky Territory and the Amur Region.
Saponins are located in the roots of Aralia. When harvesting them, plants from 5 to 15 years old are used. The roots are harvested in autumn or spring before the leaves bloom. They are dug up with crowbars and shovels. Then drying is required, most often it is carried out in special dryers, the temperature of which reaches 60 ° C. The shelf life of such raw materials is three years.