Study on the I Phase Metabolism of Ginsenoside in vitro by Ultra Performance Liquid Chromatography Coupled with Mass Spectrometry

All the drugs taken orally must undergo the process of absorption and metabolism of gastro-intestinal tract. It is difficult to conduct simply operated experiment in vivo considering the complexity of drug metabolism, such as matrix effect, individual difference and so on. Therefore, it is necessary to establish the model of drug metabolism in vitro and to study the metabolites and rules of metabolism. Drug metabolism is usually divided into 2 phases: Ⅰphase and Ⅱ phase metabolism. Ⅰ phase metabolism was taken via functionalization reactions. This study mainly researched I phase metabolism of ginseng. In vitro biotransformation of ginseng extract by intestinal flora and liver cytochrome (CYP450) in turn was performed. Firstly, ginsenoside extract was in vitro cultured with isolated intestinal bacteria under anaerobic conditions, and the incubation samples were analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC/MS). And then, the chemical fingerprint before and after metabolism were compared to identify the metabolites. 25 panaxatriol-type saponins metabolites, 15 protopanoxadiol-type saponins metabolites and one oleanane-type saponins metabolites were detected from the incubation samples, among of which were biotransformed mainly through deglycosylation and a few through oxidation reduction reaction. The metabolic profile of ginseng saponins biotransformed via intestinal flora was described based on the information of metabolites. The main intestinal bacteria metabolites (including Rh₁, Rh₂, Compound K, F₁) were studied further via rat liver cytochrome P450 enzyme (CYP450) in vitro. The CYP450 was obtained through a series of differential centrifugation steps. The incubation was under 37 ℃ in shaker incubator. All of these compounds were metabolized by redox reaction detected by UPLC/MS. The results showed that ginsenosides mainly produced deglycosylation products under the action of intestinal bacteria, and oxidation reduction reaction products under the action of CYP450. I phase metabolism plays a role in promoting drug absorption and increasing the polarity of the compounds. The results can provide an important reference for in vivo metabolism studies of ginsenosides in further.