What Is a Glycoside?

The hemiacetal hydroxyl group of a monosaccharide easily reacts with the hydroxyl group of an alcohol or a phenol, and loses water to form an acetal derivative.

Glycosides

(Thioglycosides), also called glucosinolates, produce isothiocyanates (glucosinolates) and glucose after hydrolysis. These esters are oily liquids with a certain volatility and generally have a special odor. The glycosides are widely distributed in cruciferous plants and co-exist with mustard enzymes. When Chinese herbal medicines containing such glycosides are ground with water, they are produced by enzymatic hydrolysis. Isothiocyanates are irritating or other biological. For example, the mustard oil (Sinigrin) produced by enzymatic hydrolysis of black mustard oil is propylene isothiocyanate, which is a skin redness agent for external use and has local analgesic and anti-inflammatory effects. The white mustard oil (Sinalbin) in white mustard is hydrolyzed to produce white mustard oil, namely isothiocyanate, which has a similar effect on hydroxybenzyl ester. The special odor in the root of radish is caused by the radish mustard oil produced by enzymatic hydrolysis of the glucoside (Glucoraphenln) contained in it.

Glycosides and Flavonoids

(Flavonoid glycosdes), also known as flavonoids, are a class of natural pigments widely found in the plant kingdom. It is an active ingredient in many Chinese herbal medicines, with a basic carbon frame of C6-C3-C6. Many different structures can be derived from this basic carbon frame. There are about 18 types currently known, the main ones of which are the following ones. Biflayones exist in gymnosperms such as cypress, ginkgo, and fir families. Most flavonoids combine with glucose or rhamnose to form glycosides, some of which are free or exist in combination with tannins.

Other glycosides

(1) Iridoid g1ycosides and Secoiridoid glycosides are glycosides formed from derivatives of Iridoids and sugars. It is widely distributed in the plant kingdom, especially in Rubiaceae, Scrophulariaceae, Gentianaceae, and Pulsataceae. More than 80 species have been discovered so far, and they are increasingly valued for their multiple biological activities.

Most of these ingredients are crystalline or amorphous solids, which are hygroscopic and easily melt in water, alcohol, dilute acetone and other polar solvents. It is easy to hydrolyze in case of acid. And often make plant tissue black, often have a special color reaction.

(2) Lignans and its glycosides lignans, also known as lignans, are compounds obtained by the polymerization of two molecules of phenylpropene derivatives. Most of them are in free state or combined with sugar to form glycosides. Schisandrin in Schisandra chinensis has the effect of lowering alanine aminotransferase; lignans and glycosides of many plants of the genus Podophyllum (Podophy11um) have anti-cancer effects, but they are highly toxic. Effect. The lignans are mostly white crystals with optical activity. Free ones are hardly soluble in water and soluble in organic solvents. Case of concentrated sulfuric acid.

Glycoside pharmaceutical effect

Saponins can reduce the surface tension of liquids and produce foam, so they can be used as emulsifiers. After oral administration, it can stimulate the mucous membrane of the digestive tract and reflexively promote the secretion of mucous glands in the respiratory tract and digestive tract. Therefore, it has the effect of expectorant and cough. Saponins in mulberry parasite and elderberry have rheumatoid effect. Ginsenosides have a strong and nourishing vitality effect, and play a two-way regulation or adaptation to certain pathological states of the body. Many saponins also have the functions of lowering cholesterol, anti-inflammatory, bacteriostatic, immune regulation, exciting or inhibiting the central nervous system, inhibiting gastric secretion, killing sperm, and molluscs. Some steroidal saponins also have antitumor, antifungal, bacteriostatic and cholesterol-lowering effects and are used in large quantities as raw materials for the synthesis of steroid hormones.