A high-resolution mass spectrometry-based methodology for characterization and identification of methylophiopogonanone B metabolites from cryopreserved hepatocytes and liver microsomes.

Abstract

Methylophiopogonanone B (MOB), one of the homoisoflavonoids isolated from Ophiopogon japonicus, has been demonstrated to possess antioxidative and antitumor activities. The aim of this work was to investigate the metabolism of MOB using liver microsomes and hepatocytes. MOB was individually incubated with rat, monkey, and human hepatocytes to generate the metabolites. To investigate the bioactivation pathways, MOB was incubated with liver microsomes in the presence of glutathione (GSH). All the metabolites were detected and identified using LC with a quadrupole Orbitrap mass spectrometer. Under the current conditions, nine metabolites were identified in hepatocyte incubations. Of these metabolites, M7 derived from hydroxylation was identified as the most abundant metabolite in hepatocyte incubation. MOB was metabolized via demethylation, hydroxylation, and glucuronidation. In liver microsomes, five GSH conjugates were detected and identified. MOB was subjected to bioactivation through demethylation yielding M9, which further formed quinone-methide and ortho-quinone intermediates, followed by GSH conjugation. This work is the first to study the metabolism of MOB, which will help us understand its disposition and efficacy.