1997 Volume 20 Issue 12 Pages 1274-1278
From a human intestinal bacterium, Eubacterium sp. A-44, which is capable of hydrolyzing saikosaponins to saikogenins, two glycosidases, β-D-glucosidase and a novel type of β-D-fucosidase, were isolated and characterized as saikosaponin-hydrolyzing β-D-glucosidase and prosaikogenin-hydrolyzing β-D-fucosidase.Relative to the hydrolyzing activities toward saikosaponins a, b1 and b2, the β-D-glucosidase showed lower ability to hydrolyze saikosaponin d, but no ability to hydrolyze saikosaponin c or prosaikogenins.By Sephacryl S-300 column chromatography, the molecular weight of prosaikogenin-hydrolyzing β-D-fucosidase was estimated to be about 130 kDa. The β-D-fucosidase could hydrolyze prosaikogenins A and F, but not prosaikogenins D and G or saikosaponins. Relative to p-nitrophenyl β-D-fucoside-hydrolyzing activity, this enzyme had 32.0% and 22.2% of its hydrolyzing ability toward p-nitrophenyl β-D-glucoside and p-nitrophenyl β-D-galactoside, respectively. p-Nitrophenyl β-D-fucoside-hydrolyzing activity was inhibited by D-fucose, and was weakly inhibited by D-glucose, D-glucono δ-lactone, D-galactose and D-galactono δ-lactone.By combining these two glycosidases, saikosaponins a and b1 were converted to their saikogenins via the corresponding prosaikogenins.
