The synthesis and the evaluation of the monoamine oxidase A and B inhibitory activities of 21 new substituted acylhydrazones of various aromatic aldehydes and 4-(benzyloxy) acetophenone, and four substituted semicarbazones of benzaldehyde and 4-(benzyloxy) benzaldehyde, are described. The 4-(benzyloxy) phenyl group contributing to a high lipophilicity led to the most active compounds. One of these, compound 3g (IC50= 3 nM, ...