Polysaccharide deriving from Ophiopogonis Radix promotes metabolism of ginsenosides in the present of human gut microbiota based on UPLC-MS/MS assay.

The combined usage of Ginseng Radix et Rhizoma (ginseng) and Ophiopogonis Radix is common in oriental countries for thousands of years. The major active constituents of ginseng are ginsenosides, and the conversion of ginsenosides to different metabolites by gut microbiota has been reported. However, the effect of Ophiopogonis Radix, especially its polysaccharides, on the metabolism of ginsenosides by gut microbiota is not known. Here, an in vitro metabolism of ginseng extract, or ginsenosides, in combination with or without Ophiopogon polysaccharide was conducted. A sensitive and reliable UPLC-MS/MS approach using multiple reaction monitoring (MRM) in positive ion mode was developed simultaneously to quantify 22 ginsenosides in the broth of gut microbiota. After fermentation with the microbiota, 15 ginsenosides were detected and quantified, including 6 primary ginsenosides, i.e. Rb1, Rc, Rb2, Rb3, Rd and Re, and 9 metabolites, i.e. F2, Rg3, compound K, Rh2, PPD, Rg1, Rh1, Rg2 and PPT. The quantitative results therefore revealed the elimination of primary ginsenosides and the formation of their metabolites in time-dependent manners. Furthermore, Ophiopogon polysaccharide was shown to stimulate the metabolism of ginsenosides, triggered by gut microbiota. Our study can be extended to investigate the metabolism of different Panax species by gut microbiota when combining with other herbs.