Abstract: Abstract The prosapogenins of ginsenosides have significant phamacological activities such as antitumor, antimetastatic effects. Due to low or non-existent content of the prosapogenins in normal ginseng, it is necessary and meaningful to prepare more active prosapogenin by degradation of major ginsenosides. In this paper, ginsenoside Re and Rg1 were hydrolyzed by crude enzyme of strain Microbacterium esteraromaticum GS514 and the resultant’s structures were determined using 1H NMR and 13C NMR analysis. The experimental results showed that reaction of ginsenoside Re and Rg1 with crude enzymes affected by NaCl treatment. If ginsenoside Re and Rg1 reacted with crude enzymes directly, ginsenoside Re could not be converted other ginsenosides and ginsenoside Rg1 was converted into ginsenoside F1 through selective hydrolysis of β-D-glucopyranosyl moiety connected with C6. But if the reaction were carried out in the presence of NaCl, ginsenoside Re converted into 20（S）-ginsenoside Rg2, ginsenoside Rg1 into 20（S）-ginsenoside Rh1 and 20（S）-protopanaxatriol through selective hydrolysis of β-D-glucopyranosyl moiety connected with C20．These results indicated that C20β-D-glucopyranoside enzyme was activated by NaCl, and it has significant effect on the production of different secondary ginsenosides by high regioselectivity and stereoselectivity.

Key words: Enzymatic preparation, 20(S)-Ginsenoside Rg2, 20(S)-Ginsenoside Rh1, 20(S)-PPT