In the plant kingdom a variety of chemical constituents occur in a glycoside form (conjugation with sugar). Glycosides are important, secondary metabolites. The structural diversity is a result of the vast amount of varieties and stereochemical configurations of the sugar component. Aglycones belong to terpenoid, steroid, flavonoid, quinonoid, lignan, other simple phenolics, and isothiocyanate. However, biological activities of glycosides are, in many cases, susceptible to the nature of sugar moieties, even though their aglycone is the same.
Since the 80s, plant glycosides have been attracting an increasing volume of interest from botanists and phytochemists world-wide for the following reasons:
• They are difficult to isolate and purify
• They have a very important biological function in plant life and remarkable biological activities
• They are a very important resource of natural medicine, health food, cosmetics and f
