Conversion of major ginsenoside Rb1 to ginsenoside F2 by Caulobacter leidyia.

Ginsenoside Rb1 is the most predominant ginsenoside in Panax species (ginseng) and the hydrolysis of this ginsenoside produces pharmaceutically active compounds. Caulobacter leidyia GP45, one of the isolates having strong beta-glucosidase-producing activity, converted ginsenoside Rb(1) to the active metabolites by 91%. The structures of the resultant metabolites were identified by NMR. Ginsenoside Rb1 had been consecutively converted to ginsenoside Rd (1), F2(2) and compound K (3) via the hydrolyses of 20-C beta-(1-->6)-glucoside, 3-C beta-(1-->2)-glucoside, and 3-C beta-glucose of ginsenoside Rb1.