Identification of the metabolites of anti-inflammatory compound clematichinenoside AR in rat intestinal microflora

Clematichinenoside AR (C-AR), a pentacyclic triterpenoid saponin with anti-inflammatory and anti-rheumatoid activities, is the main active component of the traditional Chinese medicine Clematidis Radix et Rhizoma. However, its poor oral absorption indicated that not only the parent compound C-AR itself, but also its metabolites could be responsible for the pharmacological effects in rats. The present study aimed to investigate the metabolism of C-AR in rat intestinal microflora, where C-AR was extensively metabolized. C-AR was incubated with the content of the large intestine. The culture solution was collected at different time points and analyzed for the metabolites of C-AR. Eight metabolites were identified by liquid chromatography/quadrupole time-of-flight mass spectrometry. M1, M2 and M5 were the major metabolites. In addition, it was proposed that deglycosylation was the only pathway contributing to the biotransformation of C-AR in rat intestinal microflora.