关键词: 生物转化, 人参内生菌, 人参皂苷Rg3, 底物特异性, Burkholderia sp.

Abstract: Many investigational studies have shown that ginsenosides are the principal active constituents of ginseng in antioxidant, antineoplastic, anti-inflammatory and biomodulatory processes. In particular, minor ginsenoside monomers, such as F2, Rh2, Rg3 and compound K (CK), have greater antitumor activity than the major ginsenoside monomers Rb1, Rb2, Rc, Rd, Re and Rg1. An endophytic bacterium GE 17-7 strain isolated from ginseng roots for 17 years, belonging to the genus Burkholderia, had been used in converting minor ginsenosides. The major ginsenoside monomers Rb1, Rb2, Rc, Rd, Re and Rg1 were used by strain GE 17-7. Biotransformation products were separated and purified through thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC) analysis and identified by spectral analysis and physical constants. The results indicated that Burkholderia sp. GE 17-7 had specific hydrolytic activity for the outer glucose at the C-20 position in protopanaxadiol-type ginsenosides without hydrolysis of the inner glucose. The final metabolite was ginsenoside Rg3 by nuclear magnetic resonance (NMR) analysis. This suggests that the hydrolytic pathway of ginsenoside Rb1 by strain GE 17-7 was ginsenoside Rb1→ginsenoside Rd→ginsenoside Rg3. We have successfully found a specificity ginsenoside Rg3-producing endophytic bacterium GE 17-7 from ginseng.

Key words: bio-transformation, ginseng endophtes, ginsenoside Rg3, substrate specificity, Burkholderia sp.