Characterization of the in vivo and in vitro metabolic profile of PAC-1 using liquid chromatography-mass spectrometry

In the present Study, the metabolic profile or PAC-1, a potential anticancer drug, Was investigated using liquid chromatography-mass spectrometric (LC/MS) techniques. Two different types of mass spectrometers - a quadrupole time-of-flight (Q-TOF) mass spectrometer and an ion trap (IT) mass spectrometer - were employed to acquire structural information oil PAC-1 metabolites. A gradient liquid chromatographic system composed of 0.2% formic acid in methanol and 0.2% formic acid in water was used for metabolite separation oil ail Agilent TC-C-18 column. A total of 16 metabolites were detected. The corresponding product ion spectra were acquired and interpreted, and structures were proposed. Accurate mass measurement using LC-Q-TOF was used to determine the elemental composition of metabolites thereby confirming the proposed structures of these metabolites. Phase I metabolic changes were predominantly observed, including debenzylation, dihydrodiol formation, hydroxylation, and dihydroxylation. The detected phase II metabolites included PAC-1 and hydroxylated PAC-1 glucuronide conjugates. Based on metabolite analysis, several PAC-1 metabolic pathways in rat were proposed. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.