Transglycosylation to Ginseng Saponins by Cyclomaltodextrin Glucanotransferases

Abstract

Ten new α-glucosylginsenosides were found to be synthesized from dextrin and four ginsenosides, -Rb₁, -Rc, -Re, and -Rg₁, by the successive actions of B. stearothermophilus cyclomaltodextrin glucanotransferase and Rhizopus glucoamylase. Seven of them were isolated in the pure state by extraction with n-butanol saturated with water, silica gel column chromatography, and high pressure liquid chromatography, and identified as 3-O-[α-D-glcp-(1→4)-β-D-glcp-(1→2)-β-D-glcp]-20-O-[β-D-glcp-(1→6)-β-D-glcp]-20(S)-protopanaxadiol, 3-O-[β-D-glcp-(1→2)-β-D-glcp]-20-O-[α-glcp-(1→4)-β-D-glcp-(1→6)-β-D-glcp]-20(S)-protopanaxadiol, 3-O-[α-D-glcp-(1→4)-β-D-glcp-(1→2)-β-D-glcp]-20-O-[α-L-araf-(1→6)-β-D-glcp]-20(S)-protopanaxadiol, 3-O-[β-D-glcp-(1→2)-β-D-glcp]-20-O-[(4^G-α-D-glcp)-α-L-araf-(1→6)-β-D-glcp]-20(S)-protopanaxadiol, 6-O-[α-L-rhap-(1→2)-β-D-glcp]-20-O-[α-D-glcp-(1→4)-β-D-glcp]-20(S)-protopanax-atriol, 6-O-[α-D-glcp-(1→4)-β-D-glcp]-20-O-(β-D-glcp)-20(S)-protopanaxatriol, and 6-O-[α-D-glcp-(1→3)-β-D-glcp]-20-O-(β-D-glcp)-20(S)-protopanaxatriol, by spectroscopy (FAB-MS, IR, ¹H-NMR and ¹³C-NMR) and hydrolysis products in 50% acetic acid. The bitterness of these α-glucosyl-ginsenosides was less than that of ginsenosides.