Conversion of protopanaxadiol type saponins to ginsenoside Rg3 by lemon.

The ability of fresh lemon (Citrus limon) to convert protopanaxadiol-type saponins into ginsenoside Rg3 was investigated, and the structures of 20(S)-ginsenoside Rg3 (1) and 20(R)-ginsenoside Rg3 (2) were identified by 1H NMR and 13C NMR spectroscopy. The experiment showed that lemon possesses the strong ability to hydrolyze ginsenosides. When protopanaxadiol-type saponins (16 mg/mL) were hydrolyzed by fresh lemon juice at 80 degrees C for 3 hrs, the conversion ratios of ginsenoside Rb1, Rb2, Rc and Rd were 92.9%, 90.0%, 96.90/0 and 55.5%, respectively, and the yields of 20(S)-ginsenoside Rg3 and 20(R)-ginsenoside Rg3 were, respectively, 31.2% and 28.3%.