LC-Q-TOF/MS-oriented systemic metabolism study of pedunculoside with in vitro and in vivo biotransformation

Abstract

As a triterpene saponin, pedunculoside is one of the most abundant, representative and active components in plants of genus Ilex (Aquifoliaceae). Pedunculoside has been used to treat myocardial ischemia, ameliorate hyperlipidemia and prevent liver injury. In this paper, a systemic in vitro liver microsomes / S9 and intestinal bacteria incubation, and in vivo animal experiment were performed, using LC-Q-TOF/MS analysis and a three-step data processing protocol. As a result, Bifidobacterium adolescentis and Bifidobacterium breve were identified to potentially metabolize pedunculoside among the intestinal bacteria tested. A total of 11 metabolites were found and tentatively identified, with 6 in both microsomal and bacterial incubation systems, and 9 after rats orally administered with pedunculoside. The metabolites detected involving both phase I and phase II metabolism, mainly through deglycosylation (hydrolyzation), dehydrogenation, hydroxylation and conjugation, and some of them underwent more than one-step metabolic reactions. Most of the metabolites have not been reported before. In vitro, liver microsome and intestinal bacteria prefer to metabolize pedunculoside in totally different ways; while in vivo, intestinal tract is the most important site for the metabolism and excretion of pedunculoside, where both intestinal bacteria and the host metabolic enzymes participate in its metabolism and disposition. The importance of intestinal bacteria should be highlighted. This study would contribute to a better understanding of pedunculoside metabolism, which can provide scientific evidence for its pharmacodynamic mechanism research and prove its clinical application.