Synthesis of oleanolic acid saponins mimicking components of Chinese folk medicine Di Wu

3,28-Di-O-rhamnosylated oleanolic acid saponins, mimicking components of Chinese folk medicine Di Wu, have been designed and synthesized. one-pot glycosylation and 'inverse procedure' technologies have been applied thus significantly simplifying the preparation of desired saponins. The cytotoxic activity of compounds 3-O-[alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-xylopyranosyl]oleanolic acid 28-O-[alpha-L-rhamnopyranosyl-(1 -> 4)-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl] ester (3), 3-O-[alpha-L-rhamnopyranosyl]oleanolic acid 28-O-[alpha-L-rhamnopyranosyl- (1 -> 4)-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl] ester (4), 3-O-[alpha-L-rhamnopyranosyl]oleanolic acid 28-O-[alpha-L-rhamnopyranosyl] ester (5), and 3-O-[alpha-L-rhamnopyranosyl]oleanolic acid 28-O-[6-O-(alpha-L-rhamnopyranosyl)hexyl] ester (6) was preliminarily evaluated against HL-60 human promyelocytic leukemia cells. The natural saponin 3 and designed saponin 4 exhibited comparable moderate cytotoxic activity under our testing conditions. (C) 2009 Elsevier Ltd. All rights reserved.