人参皂苷Rb1转化菌株筛选及转化产物分析

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

摘要:

【背景】许多微生物能够对皂苷类化合物进行生物转化，因此，通过微生物对皂苷类化合物不同位置结构的修饰能获得高活性的皂苷成分。【目的】从分离纯化的菌株中筛选能将人参皂苷Rb₁转化为药理活性较高的稀有人参皂苷。【方法】从三七根际土壤及三七茎中分离纯化了36株真菌，首先利用产β-葡萄糖苷酶的方法对菌株进行皂苷转化活性初筛，再以人参皂苷Rb₁为底物进行皂苷转化活性复筛，通过薄层色谱(thin layer chromatography, TLC)、高效液相色谱(high performance liquid chromatography, HPLC)和质谱(mass spectrometry, MS)等方法对转化产物进行分析。【结果】筛选出一株对人参皂苷Rb₁具有较高转化活性的菌株F17，通过形态学观察及对内转录间隔区(internal transcribed spacer, ITS)序列分析，菌株F17被鉴定为拟盘多毛孢属菌(Pestalotiopsis biciliata)。P. biciliata可将人参皂苷Rb₁转化为人参皂苷Rd、稀有人参皂苷F₂和C-K，转化路径为Rb₁→Rd→F₂→C-K。【结论】本研究为稀有人参皂苷F₂和C-K的微生物转化提供了新的菌种来源。

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.