Screening of a strain for ginsenoside Rb1 transformation and analysis of its saponin products

Abstract:

[Background] Microbial transformation is an important means for structural modification of natural products. Many microorganisms can transform ginsenoside compounds into saponins with high activity by modifying the structure of different positions.[Objective] To screen a strain that can transform ginsenoside Rb₁ into rare ginsenosides with high pharmacological activity. [Methods] A total of 36 fungal strains were isolated from rhizosphere soil and stem of Panax notoginseng and purified. Primary screening of saponin transformation activity was performed with β-glucosidase method, followed by a second screening with ginsenoside Rb₁ as substrate. The transformation products were analyzed by TLC, HPLC, and MS. [Results] A strain F17 with high transformation activity of ginsenoside Rb₁ was screened out and it was identified as Pestalotiopsis biciliata based on morphological observation and ITS sequence analysis. It can transform ginsenoside Rb₁ into ginsenoside Rd and rare ginsenosides F₂ and C-K through the pathway of Rb₁→Rd→F₂→C-K. [Conclusion] This study provides a new strain for transformation of rare ginsenosides F₂ and C-K.