AOX1

Aldehyde oxidase 1 (AOX1) is a cytosolic molybdo-flavoenzyme that catalyzes aldehyde oxidation and N-heterocycle hydroxylation, positioning the enzyme as a major component of phase I xenobiotic metabolism and drug biotransformation pathways^[1][2]. Mechanistically, AOX1 requires a molybdenum cofactor, flavin adenine dinucleotide, and iron-sulfur clusters for catalytic activity, enabling broad substrate recognition across endogenous aldehydes and therapeutic compounds^[3]. Therefore, AOX1 has become an important determinant of drug clearance, metabolic stability, and pharmacokinetic variability during preclinical drug development^[2][4]. In disease-related models, altered AOX1 expression has been associated with reactive oxygen species production and downstream signaling regulation, including activation of the Wnt/β-catenin pathway in gallbladder carcinoma models^[5]. Compared with related aldehyde oxidase isoforms, human AOX1 is the only catalytically active aldehyde oxidase gene in humans, whereas rodents possess multiple functional homologs, including Aox1, Aox3, Aox4, and Aox3l1, with distinct tissue distributions and physiological specialization^[3]. This species-specific organization complicates translational interpretation of animal studies and highlights AOX1 as the principal human aldehyde oxidase relevant to pharmacology and toxicology^[3][4]. For experimental applications, AOX1 inhibitors such as menadione and raloxifene are widely used to distinguish AOX1-mediated metabolism from cytochrome P450-dependent pathways and to characterize metabolic liabilities of drug candidates^[4].