Glycosides

Glycoside: is an organic compound, usually of plant origin, that is composed of a sugar portion linked to a non-sugar moiety by glycosidic bond. The sugar portion is called glycon, while the non-sugar portion is called aglycon or genin; therefore glycosides yield one or more sugars among the products upon hydrolysis.

Physical and chemical properties of glycosides:
Because of the complexity of the structure of the naturally occurring glycosides, no generalization are possible with regard to their stability. In addition there are differences in their solubility properties. Many glycosides are soluble in water or hydroalcoholic solutions because the solubility properties of the sugar residues exert a considerable effect i.e. sugar moiety increases water solubility.
The aglycon part is soluble in non-polar solvents like benzene and ether.


Classification of glycosides

Biosynthesis of glycosides:
The principal pathway of glycoside formation involves the transfere of uridylyl group from uridine triphosphate to a sugar 1-phosphate. Enzymes catalyzing this reaction are referred to as uridylyl transferases (1). The subsequent reaction, mediated by glycosyl transferases (2), involves the transfer of sugar from uridine diphosphate to a suitable acceptor ( aglycon), thus forming glycoside.

Extraction of glycosides