Metabolism of Mequindox in Scophthalmus Maximus by Liquid Chromatography High–Resolution Mass Spectrometry

Abstract

Mequindox (MEQ), a member of Quinoxaline 1, 4–di–N–oxides (QdNOs), has been applied in Scophthalmus maximus farming industry. Due to the severe toxic effects of QdNOs, the residue of MEQ and potential metabolites in Scophthalmus maximus might cause serious food safety risk. In this work, metabolism of MEQ in Scophthalmus maximus in vivo was firstly investigated. Eight metabolites are identified with hydrogenation reduction, desoxygenation, deacetylation, methyl mono–hydroxylation, and their combinations as major metabolic pathways. Different from land farm animal with desoxygenation as major metabolic pathway, carbonyl reduction is the major metabolic pathway in Scophthalmus maximus. In addition, M8 (3–methylol–BDMEQ) is first discovered in aquatic organisms with methyl mono–hydroxylation as a novel metabolic pathway, and M7 (Deacetyl–4–DMEQ) is the first metabolite to be detected in an organism undergoing both N→O deoxygenation and deacetylation reactions. This work reveals marine drug metabolism in aquatic animals, which will support for the residue marker confirmation and facilitate further toxicity and food safety evaluation of MEQ in marine foods.

Keywords: Mequindox, Scophthalmus maximus, Metabolism, LC-HRMS, Aquatic animals, Metabolic Pathway