Synthesis and anti-HIV activity of triterpene 3-o-galactopyranosides, analogs of glycyrrhizic acid

A new method for synthesizing triterpene 3-O-galactosides, analogs of glycyrrhizic acid (GA) based on 18β- glycyrrhetic acid (GLA) methyl esters and 18,19-dehydro-GLA, using 2,3,4,6-tetra-O-acetyl-α-Dgalactopyranosyl bromide as the glycosyl donor, I-Br promoter, and 4-Å molecular sieves was developed. The method could produce primarily 3-O-α-D- or β-D-galactopyranosides depending on the reaction conditions. The 3-O-α-D-galactopyranoside of GLA exhibited an index of selectivity (IS) 2.9 times greater than that of GA for inhibition of accumulation of virus-specific protein p24 of HIV-1. β-D-Galactopyranoside of GLA was more cytotoxic for MT-4 cells and exhibited weak anti-HIV-1 activity.