Anthracene Glycosides

It is postulated that the aglycone part of these glycosides is formed by head-to-tail condensation of acetate units. This group of glycosides comprises of different aglycone moieties like

• • • • • Anthraquione,

        • Anthrone,

        • Anthranol,

        • Dianthranol,

        • Oxanthrone and dianthrone.

In different drugs like aloe, senna, rhubarb, cascara, aglycones are present in their derivative forms.

The parent molecule for all these aglycones i.e, anthraquinone is present in different forms along with methyl, hydroxymethyl, carboxyl, dihydroxy phenol, trihydroxy phenol or free carboxylic acid groups.

In a reduced form, anthraquinone is present as anthranol or anthrone which areisomeric with each other.

Anthrone is pale yellow substance and without any solubility in alkali while anthranol is brownish-yellow and soluble in alkali.

Anthranol shows strong fluorescence in alkali, but anthrone is non-fluorescent in nature.

Oxanthrone is the intermediate substance from anthraquinone to anthranol.

Anthrone molecule orients in bimeric form called dianthrone present in few plants.

The reduced anthraquinones are biologically more active.

In a fresh drug, these aglycones are present in reduced form, but are hydrolysed and oxidized during their storage.

They are present along with different sugars like glucose, rhamnose, arabinose and primeverose.