Bay calyx saponin element-3-O-b-D-glucopyranosyl-28-O-b-D-xylopyranosyl-(1/6)-[b-D-glucopyranosyl-(1/4)-a-L-rhamnopyranosyl-(1/2)]-b-D-glucopyranoside was dissolved in MeOH (0.2 mL), and TFA (2N, 1 mL) was added. The mixture was heated at 95°C for 24 h and the reaction was monitored by TLC. The residue was evaporated and the acid was removed by repeated addition of MeOH. The residue was analyzed and identified by silica gel TLC using CHCl3:MeOH:H2O (3:1.5:0.2), and then the product was obtained by silica gel separation using the same eluent.
