Drug Biotransformation Modeling on Maldi Target Using Multiwell Photocatalytic Microreactor Device

Metabolic conversion of drugs to chemically reactive products, known as bioactivation, is considered to underlie the adverse drug reactions such as idiosyncratic hepatotoxicity. As bioactivation of most drugs involves phase I oxidation, UV-induced TiO 2 photocatalytic oxidation (UV/TiO 2 -PCO) can be used as a fast, simple and inexpensive non-enzymatic method of oxidative metabolism simulation allowing for rapid preliminary screening of candidate drugs for reactive metabolite formation. We developed and evaluated a prototype 96-well on-target UV/TiO 2 -photocatalytic microreactor (PCμR96) setup that integrates drug metabolism simulation and sample preparation directly on a MALDI target. PCμR96 allows to sequentially perform UV/TiO 2 -PCO of xenobiotics, GSH or protein adduct formation, protein digestion and sample concentration, followed by surface- or matrix-assisted laser desorption ionization (SALDI/MALDI) mass spectrometry (MS). Oxidation products of amodiaquine (AQ) and their protein adducts were obtained using PCμR96 and identified by SALDI and MALDI MS/MS analysis. The achieved AQ oxidation products were in good agreement with the known AQ metabolites produced in biological systems. Two of the products were proved to be reactive towards cysteyl thiols of human globin