SYNTHESIS OF BAICALIN DERIVATIVES AND EVALUATION OF THEIR ANTI-HUMAN IMMUNODEFICIENCY VIRUS(HIV-1)ACTIVITY

The aglycone baicalien(1) and the key intermediate 5,6-O-dibenzyl-baicalien(3) were prepared from baicalin in order to evaluate the influence of different glycosyloxies linked to baicalien on anti-HIV activity. Four new flavoneglycosides namely 5-hydroxyl-6-O-benzyl-flavone-7-β-D-glucoside(12), 5-hydroxyl-6-O-benzyl-flavone-7-β-D-galactoside(13), 5-hydroxyl-6-O-benzyl-flavone-7-α-D-mannoside(14) and 5-hydroxyl-6-O-benzyl-flavone-7-α-D-arabinoside(15) were synthesized by condensation of the corresponding protected glycosyl bromides with (3). Biological activity test showed that (a) both baicalin and baicalien inhibited HIV-1 RT; (b) the 6hydroxyl substitution of baicalin and baicalien is necessary for their inhibitory activity on HIV-1 RT; (c) the HIV-1 inhibitory activity and cytotoxicity of baicalien were higher than those of baicalin, the two compounds were found to have almost identical therapeutic index.