4-Aminobenzoic acid hydrazide inhibition of microperoxidase-11: Catalytic inhibition by reactive metabolites

► 4-ABAH mediated MP-11 inhibition. ► MP-11 mediated hydrazides oxidation leading to the generation of carbonyl radicals. ► Modest decrease in MP-11 inhibition in presence of DMPO. ► Covalent adduct formation of MP-11 and hydrazides leading to heme alteration.