Monoamine oxidase [9001-66-5]

Monoamine oxidase, an enzyme comprising various polypeptides, catalyzes the oxidative deamination of diverse biological amines within both brain and peripheral tissues, yielding hydrogen peroxide in the process. This enzyme is crucial for regulating synaptic transmission, emotional behavior, and other cerebral functions [1] [2].

Monoamine oxidase (MAO) is a flavoenzyme that catalyzes the oxidative deamination of amines, producing hydrogen peroxide. Two isoforms, MAO-A and MAO-B, exhibit distinct substrate and inhibitor specificities. In vitro inhibition data from the literature report IC₅₀ values for various compounds: acridine orange is a MAO-A-specific inhibitor (IC₅₀ = 0.017 µM), oxazine 170 is MAO-B-specific (IC₅₀ = 0.0065 µM), and Darrow red is non-specific (MAO-A IC₅₀ = 0.059 µM; MAO-B IC₅₀ = 0.065 µM). Heterocyclic chalcones, such as compound 4h, show MAO-B inhibition (IC₅₀ = 0.067 µM), while 2,1-benzisoxazole derivatives like 7a inhibit MAO-B (IC₅₀ = 0.017 µM).

Monoamine oxidase A (MAO A) knockout mice exhibit hyperserotonemia and serve as an autism spectrum disorder model (PMID: 36243286). In these mice, oral administration of selegiline (10 mg/kg/day) alleviates depressive-like behaviors (PMID: 40373631). MAO A deficiency leads to maladaptive defensive behaviors, including neophobia and reduced risk assessment, without altering sensory functions (PMID: 21156093).