Shenzhen Key Laboratory of Edible and Medicinal Bioresources, HKUST Shenzhen Research Institute, Shenzhen 518057, China.
Division of Life Science and Center for Chinese Medicine, The Hong Kong University of Science and Technology, Hong Kong 999077, China.
Molecules. 2019 Aug 8;24(16):2886. doi: 10.3390/molecules24162886.
Gut microbiota play an important role in metabolism of intake saponins, and parallelly, the polysaccharides deriving from herbal products possess effects on gut microbiota. Ophiopogonis Radix is a common Chinese herb that is popularly used as functional food in China. Polysaccharide and steroidal saponin, e.g., ophiopogonin, mainly ophiopogonin D (Oph-D) and ophiopogonin D' (Oph-D'), are the major constituents in this herb. In order to reveal the role of gut microbiota in metabolizing ophiopogonin, an in vitro metabolism of Oph-D and Oph-D' by human gut microbiota, in combination with or without polysaccharide, was conducted. A sensitive and reliable UPLC-MS/MS method was developed to simultaneously quantify Oph-D, Oph-D' and their final metabolites, i.e., ruscogenin and diosgenin in the broth of microbiota. An elimination of Oph-D and Oph-D' was revealed in a time-dependent manner, as well as the recognition of a parallel increase of ruscogenin and diosgenin. polysaccharide was shown to stimulate the gut microbiota-induced metabolism of ophiopogonins. This promoting effect was further verified by increased activities of β-D-glucosidase, β-D-xylosidase, α-L-rhamnosidase and β-D-fucosidase in the broth. This study can be extended to investigate the metabolism of steroidal saponins by gut microbiota when combined with other herbal products, especially those herbs enriched with polysaccharides.
肠道微生物在摄入皂苷的代谢中起着重要作用，而来自草药产品的多糖则对肠道微生物群具有影响。麦冬是一种常见的中草药，在中国作为功能食品广受欢迎。多糖和甾体皂苷，如麦冬皂苷 D（Oph-D）和麦冬皂苷 D'（Oph-D'），是这种草药的主要成分。为了揭示肠道微生物群在代谢麦冬皂苷中的作用，我们进行了体外实验，用人肠道微生物群代谢 Oph-D 和 Oph-D'，同时或不与多糖结合。建立了一种灵敏可靠的 UPLC-MS/MS 方法，用于同时定量检测微生物群肉汤中的 Oph-D、Oph-D'及其终代谢产物鲁斯可苷元和薯蓣皂苷元。结果显示，Oph-D 和 Oph-D'随时间呈消除趋势，同时鲁斯可苷元和薯蓣皂苷元的浓度平行增加。多糖可刺激肠道微生物群诱导的麦冬皂苷代谢。这一促进作用通过增加肉汤中β-D-葡萄糖苷酶、β-D-木糖苷酶、α-L-鼠李糖苷酶和β-D-岩藻糖苷酶的活性进一步得到验证。本研究可扩展到研究肠道微生物群与其他草药产品（特别是富含多糖的草药）结合时对甾体皂苷的代谢。
