Monoamine oxidase inhibitory activities of novel 3,4-dihydroquinolin-(1H)-2-one derivatives.

Three 3,4-dihydroquinoline-(1H)-2-one derivatives were synthesized and their monoamine oxidase (MAO) inhibitory activities were evaluated. The calculated IC(50) values revealed that compound Q (N-amino-3,4-dihydroquinoline-(1H)-2-one), which carries a free amine group in the molecule, inhibited rat liver MAO-B competitively and reversibly suggesting that this relatively small compound may interact with the active site channel of the enzyme while the compounds QB (1-(benzlyden-amino)-3,4-dihydroquinoline-(1H)-2-one), PCN (2-(3-cyano-2-oxo-4-phenyl-2H-quinolin-1-yl-N-cyclohexyl-2-(4'-chlorophenyl) acetamide) and MG (tert-butyl-N-[cyclohexylcarbamoyl-(3-hydroxyphenyl)methyl]-N-(2-benzoylphenyl)-carbamate) inhibited rat liver MAO-B non-competitively and irreversibly, suggesting that these compounds may interact with another hydrophobic binding region outside of the active site of the enzyme.