Hydrolysis of the outer β-(1,2)-d-glucose linkage at the C-3 position of ginsenosides by a commercial β-galactosidase and its use in the production of minor ginsenosides

Commercial β-galactosidase from Aspergillus oryzae (SUMILACT LTM) was used for the bioconversion of the ginsenosides Rb1, Rb2, Rc, Rd, and Rg3 to gypenoside-XVII, compound-O, compound-MC1, F2, and Rh2, respectively. The optimal conditions were pH 4.5, 50 °C, 60 U·mL−1 enzyme, and 8.0 mM substrate. Interestingly, the enzyme hydrolyzed only the outer β-(1,2)-d-glucose linkage at the C-3 position of ginsenosides. Under optimum conditions, the enzyme completely converted Rb1, Rb2, Rc, Rd, and Rg3 to gypenoside-XVII, compound-O, compound-MC1, F2, and Rh2, respectively, with the highest productivity.