Monoamine Oxidase and Cholinesterase Inhibition Profiles of Semicarbazone and Thiosemicarbazone Derivatives

Abstract Twenty semicarbazone and thiosemicarbazone derivatives (T1–T20) were synthesized and evaluated for their inhibition of monoamine oxidases and cholinesterases. Most compounds showed stronger inhibition of MAO‐B than MAO‐A. Among the synthesized compounds, T6 most strongly inhibited MAO‐B (IC50 = 6.45 µM), followed by T17 (IC50 = 9.46 µM). T6 and T17 exhibited the highest selectivity index values (3.60 and >4.23, respectively) for MAO‐B as compared with MAO‐A. T6 was a competitive MAO‐B inhibitor. Regarding structure–activity relationship, the thiosemicarbazone T1 (IC50