Glycosides, also called glycosides, generally refer to monosaccharideSemiacetal hydroxylAcetal derivatives formed by reaction with hydroxyl group of alcohol or phenol and dehydration.A class of glycoside organic compounds, generally whitecrystalIt is widely found in plants, such as plantain, liquorice, tangerine peel, etc., which contain glycosides.
Also calledGlycoside。It is the semi acetal hydroxyl of monosaccharide or oligosaccharide and the hydroxylaminoOr sulfur hydroxyl, etchydrate。Therefore, a glycoside can be divided into two parts.One part is the sugar residue (the sugar removes the semi acetal hydroxyl group), and the other part is the ligand (the non sugar part), whose bond is called glycosidic bond.The ligand part can be very simple or very complex.Glycoside bonds can be linked to each other by oxygen, sulfur, and nitrogen atoms, and their glycosides are referred to as O-glycosides, S-glycosides, N-glycosides, or C-glycosides, respectively.The ligand of glycoside can be sugar, so it can be condenseddisaccharide, oligosaccharides and polysaccharides.
Glycosides are widely distributed in roots, stems, leaves, flowers and fruits of plants.Most are colored crystals, which are soluble in water.It is generally bitter in taste.Some are highly toxic.hydrolysisIt can produce sugar and other substances.for exampleAmygdalin（amygdalin）CtwentyHtwenty-sevenNOelevenThe final product of hydrolysis is glucose CsixHtwelveOsix、BenzaldehydeCsixHfiveCHO andHydrocyanic acidHCN。Glycosides can be used as medicines.The effective components of many Chinese medicines are glycosides, such asBupleurum chinense、Chinese bellflower, Yuanzhi, etc.Due to the different stereo configurations, glycosides haveαandβTwo types.Glucoside (glucoside) and other glycosides, most of which areβ-Type glycoside[1]。
character
1. Most glycosides are colorless, odorless and bitter.A few glycosides are colored, such as flavonoid glycosides, anthracene glycosides, anthocyanins, etc.A few have sweet taste, such as liquoricesaponin 。
2. Most glycosides are neutral or acidic, and a few are alkaline.
3. Most glycosides are soluble in water and ethanol, and some glycosides are soluble inethyl acetateAnd chloroform, insoluble inEther、Petroleum ether, benzene, etcOrganic solvent。The solubility of glycosides in water or other solvents with high polarity generally increases with the increase of the number of sugar molecules combined.The nature of aglycones can also affect the solubility of glycosides.If cyanohydrin is in waterSolubleThe flavonoid glycosides are difficult to dissolve.Aglycones are insoluble in water and soluble in organic solvents.
4. Glycosides are easy to be hydrolyzed by dilute acid or enzyme to produce sugar and aglycone.However, there are several sugar molecules in the original glycosides in some plants, which are called primary glycosides. During hydrolysis, some sugar molecules can be removed first to generate secondary glycosides with fewer sugar molecules, and the secondary glycosides can be further hydrolyzed to obtain sugar and aglycones.After glycosides are hydrolyzed into glycosides, their solubility and efficacy in water are often greatly reduced. Therefore, attention must be paid to preventing hydrolysis when collecting, processing, storing and manufacturing Chinese herbal medicines containing glycosides.For example, try to reduce the breakage of plant body during collection, dry it as soon as possible after collection, keep it dry during storage, and do notaqueous solutionOr in acid solution for a long time.B-GlucosidaseIt not only has the saccharification of cellulose, but also has a close relationship with terpene aroma precursors[1]。
5. Natural glycosides generally have certain optical activity (mostly left-handed) and no reducibility.After hydrolysis, due to the formation ofreducing sugar, tends to become dextral andReducibility。This property can be used to identify glycosides in Chinese herbal medicine.The reducibility before and after hydrolysis is usually checked by Fehling test.
6. Some glycosides such assaponin 、Flavonoid glycosideCan be mixed with lead acetate orBasic lead acetateThe reagent generates precipitation, which can be restored to the original glucoside after lead removal.This property can be used for the extraction of glycosides.
Glycosides can be divided intoOxyglycoside, glucosinolate, nitrogen glycoside, carbon glycoside, selenium glycoside, etc., of which oxygen glycoside refers to a compound formed by dehydration of the semiacetal or ketal hydroxyl of a sugar and the hydroxyl of another monosaccharide or the hydroxyl of an alcohol or a phenol (seenucleosideNaming section).
(1) Naming of oxygen glycosides: simple aglycones are named with glycosides, and the name of aglycones is written at the front of the name or between sugar and glycoside;Complex aglycones can be named as substituents.
(2) Naming of glucosinolate: glucosinolate refers to the compound whose oxygen atom at position 1 of glucosinolate is replaced by sulfur. Its naming is similar to that of glucosinolate, except that the position of sulfur is marked after the name of aglycone or the word "sulfur (generation)" is added before the glycoside.When aglycones are complex, they can also be named by using aglycones as parent and sugar as substituent.
(3) Name of carbon glycoside compound: carbon glycoside refers to the compound formed by removing a molecule of water between the terminal hydroxyl of sugar and the hydrogen on the carbon atom of aglycone. Its name is based on aglycone as the parent and sugar as the substituent.[2]
Main categories
Announce
edit
Sulfur-containing glycoside
(Thioglycosides), also known as glucosinolates, generates isothiocyanates after hydrolysis（Mustard oil）And glucose.These esters are volatile oily liquids with special smell. This kind of glycoside is widely distributed in cruciferous plants and coexists with myrosinase. When Chinese herbal medicine containing this kind of glycoside is ground with water, it is generated by enzymatic hydrolysisIsothiocyanateIt is of stimulating or other biological nature.For example, the black mustard oil generated after enzymolysis of sinigrin in mustard seed isPropylene isothiocyanateFor external use, it is a skin reddening agent with local analgesic and anti-inflammatory effects.Sinalbin in white mustard seed is enzymatically hydrolyzed to produce white mustard oil, i.e. isothiocyanate pairhydroxylBenzyl ester has similar effect.The special smell in the radish root is caused by the radish mustard oil produced after the enzymatic hydrolysis of the glucosamine contained in the radish root.
Flavonoids and flavonoid glycosides
(Flavonoid glycosides), also known as flavins, is a kind of natural pigment widely existing in the plant kingdom.It is an effective ingredient in many Chinese herbal medicines and has a C6-C3-C6 basic carbon frame.Many different structures can be derived from this basic carbon frame.At present, there are about 18 known types, of which the main types are as follows:TaxodiaceaeBiflavanones also exist in gymnosperms.majorityFlavonoidsIt combines with glucose or rhamnose to form glycosides, some of which are free or withTanninCombination exists.
Other classes
（1）IridoidIridoid g1ycosides and secoiridoid glycosides are glycosides composed of iridoid derivatives and sugars.Widely distributed in the plant kingdom, especiallyRubia cordifoliaFamily, Scrophulariaceae, Gentianaceae, Pyrola family, etcGardenia, Scrophularia, Gentiana, Pyrola, etc.At present, more than 80 species have been found, because there are manybiological activityAnd is increasingly valued.
Most of these ingredients are crystalline orAmorphous solidIt is hygroscopic and easy to melt in water, alcohol, dilute acetone and other solvents with high polarity.It is easy to hydrolyze in case of acid.It often darkens plant tissue, and there are specialChromogenic reaction。
（2）LignanLignans and its glycoside lignans, also called lignans, are composed of two molecules of phenylpropenederivativePolymerized compounds.Most of them are free or combine with sugar to form glycosides.Schisandra chinensisInSchisandrinWith Descending Grain CtransaminaseThe role of;Lignans and their glycosides from various plants of Podophyllum have anti-cancer effects, but are highly toxicSesaminOnly the synergism of pesticides.Lignans are mostly white crystals with optical activity. Most of them are insoluble in water and soluble in organic solvents.Coloring in case of concentrated sulfuric acid.
Pharmaceutical effect
saponin Class A can reduce the surface tension of liquid and produce foam, so it can be used as emulsifier.After taking orally, it can stimulate the mucous membrane of the digestive tract and reflexively promote the secretion of the mucous glands of the respiratory tract and digestive tract, so it has the effect of eliminating phlegm and relieving cough. For example, Platycodon grandiflorum, Polygala tenuifolia and Aster are commonly used as expectorants.Saponins from mulberry parasitism and elderberry have the function of dispelling wind and dampness.GinsenosideIt has the function of strengthening and replenishing vital energy, and plays a two-way regulation or adaptation role in some pathological states of the body.Many saponins also have cholesterol lowering, anti-inflammatory, bacteriostatic, immune regulation, excitation or inhibitionCentral nervous systemIt can inhibit the secretion of gastric juice, kill sperm and molluscs.SomeSteroidal saponinIt also has anti-tumor, antifungal, bacteriostatic and cholesterol lowering effects, and is widely used as a raw material for the synthesis of steroid hormones.
