Production of Minor Ginsenosides from Panax notoginseng Flowers by Cladosporium xylophilum

Panax notoginseng flowers have the highest content of saponins compared to the other parts of Panax notoginseng, but minor ginsenosides have higher pharmacological activity than the main natural ginsenosides. Therefore, this study focused on the transformation of the main ginsenosides in Panax notoginseng flowers to minor ginsenosides using the fungus of Cladosporium xylophilum isolated from soil. The main ginsenosides Rb-1, Rb-2, Rb-3, and Rc and the notoginsenoside Fa in Panax notoginseng flowers were transformed into the ginsenosides F-2 and Rd(2), the notoginsenosides Fd and Fe, and the ginsenoside R-7; the conversion rates were 100, 100, 100, 88.5, and 100%, respectively. The transformation products were studied by TLC, HPLC, and MS analyses, and the biotransformation pathways of the major ginsenosides were proposed. In addition, the purified enzyme of the fungus was prepared with the molecular weight of 66.4 kDa. The transformation of the monomer ginsenosides by the crude enzyme is consistent with that by the fungus. Additionally, three saponins were isolated from the transformation products and identified as the ginsenoside Rd(2) and the notoginsenosides Fe and Fd by NMR and MS analyses. This study provided a unique and powerful microbial strain for efficiently transformating major ginsenosides in P. notoginseng flowers to minor ginsenosides, which will help raise the functional and economic value of the P. notoginseng flower.

Automated summary

This study identified a microbial strain that can efficiently transform major ginsenosides in Panax notoginseng flowers into minor ginsenosides, thereby enhancing the functional and economic value of the flowers.