4-Aminobenzoic acid hydrazide

4-Aminobenzoic acid hydrazide (CAS No.: 5351-17-7) is a small-molecule hydrazide derivative widely used in biomedical research as a selective and irreversible inhibitor of myeloperoxidase (MPO), a heme-containing enzyme involved in innate immune responses and inflammatory oxidative processes. It exerts its activity through covalent modification of the MPO active site, leading to sustained suppression of enzymatic function and consequent reduction in the formation of reactive oxidants such as hypochlorous acid, with inhibitory potency in the submicromolar range. In cellular systems, this compound attenuates MPO-dependent oxidative damage and modulates neutrophil effector functions, including inhibition of phorbol ester-induced neutrophil extracellular trap formation and suppression of oxidant production triggered by inflammatory stimuli, while also influencing reactive oxygen species dynamics in neutrophils at higher concentrations. Functionally, it is commonly applied to investigate MPO-driven signaling pathways, oxidative stress mechanisms, and inflammatory responses, particularly in the context of neuroinflammation and ischemic injury. In vivo studies have demonstrated its utility in reducing infarct size, improving neurological outcomes, and enhancing survival in experimental models of cerebral ischemia, supporting its role as a pharmacological tool in stroke and inflammation research. Experimental concentrations or dosing regimens vary depending on the specific cellular or animal model and study design.