Contains few sugar groups and is crystalline

The sugar-containing base is mostly amorphous powder

subtopic

Generally tasteless

Soluble in methanol, ethanol, aqueous n-butanol and other hydrophilic organic solvents

A lipophilic organic solvent that is poorly soluble in petroleum ether, benzene and chloroform.

Easily soluble in organic solvents

Hardly soluble in water (some are soluble in petroleum ether, some are insoluble)

The more sugar groups, the greater the water solubility

Environment: water or dilute alcohol

Dilute hydrochloric acid, dilute sulfuric acid, acetic acid, formic acid, etc.

Mechanism: protonation of glycoside bond atoms (key) - cleavage of glycoside bonds to form cationic carbon ions and sugar cationic intermediates - solvation of cationic carbon ions in water - removal of protons to form sugar molecules

Hydrolysis rules

The acetal structure is stable and generally does not undergo alkali hydrolysis.

Ester glycosides, phenolic glycosides, dilute alcohol glycosides or glycosides with β-electron-withdrawing substitutions, subject to alkaline hydrolysis

Mild, it protects the structure of sugar and aglycone unchanged, and can also obtain secondary glycosides, aglycone and sugar, and the connection method of sugar and sugar.

Exclusive:

Reagents: acetic anhydride and acid (commonly used sulfuric acid, perchloric acid, Lewis acid-zinc chloride, boron trifluoride, etc.)

Difficulty level: 1→6 glycoside bonds>1→4>1→3>1→2

Principle: Periodic acid oxidizes the ortho-diol hydroxyl structure of the sugar (not the ortho-diol hydroxyl group of the glycoside), and then sodium tetrahydroborate reduces it to the glycol, which is unstable in acid Hydrolyze to obtain native aglycone (the reaction conditions are mild, suitable for oxyglycosides with unstable aglycone structures and carbon glycosides that are difficult to hydrolyze)

Solubility (pay attention to killing enzymes and protecting glycosides), commonly used system solvent method

Maintain neutral conditions to prevent hydrolysis of glycosides Add calcium carbonate during extraction, or use methanol, ethanol, or boiling water

The aglycone has strong fat solubility and is generally extracted with organic solvents such as ether and chloroform.

First elute the large polar components of sugars with water, and then use ethanol (concentration from low to high) to separate the glycosides

Strongly lipophilic glycosides and aglycones: silica gel adsorption column

Highly polar glycosides: silica gel or cellulose distribution column chromatography, water-saturated organic solvent as eluent

Polyamide chromatography

Forward: n-butanol-acetic acid-water, chloroform-methanol-water, ethyl acetate-n-butanol-water

Reverse: acetonitrile-water, methanol-water

sugar

aglycone

Alcohol glycosides

Phenolic glycosides

ester glycosides

Cyanogenic glycoside: a-hydroxynitrile structure

carotene

Myrosin

Guanosine, adenosine, cytidine

Crotonin

Aloe glycoside, aloe vera glycoside

The aglycones are mostly flavonoids, anthrones, and anthraquinones.

Electron impact mass spectrometry (EI) is generally not used

Chemical ionization (CI), field desorption (FD), fast atom bombardment (FAB), electrospray (ESI)