Thiazole derivatives as inhibitors of purified bovine liver mitochondrial monoamine oxidase-B: structure-activity relationships and theoretical study.

Structure-activity relationships were performed on a new series of thiazole derivatives which selectively inactivate monoamine oxidase-B (MAO-B), purified from mitochondrial beef liver. All of the synthesized and tested compounds showed non-competitive inhibition, suggesting the formation of a stable adduct between the tertiary amine function, linked to the thiazolyl derivatives and the active site of the enzyme. The mechanism of MAO-B inhibition is discussed in terms of the Ionization Potential of the amine nitrogen atom and the conformational flexibility of the inhibitors.

Structure-activity studies on monoamine oxidase inhibitors by calorimetric and quantum mechanical calculations.

Structure-activity relationship studies were carried out on a new series of hydrazino-thiosemicarbazide derivatives, which inhibit monoamino oxidase (MAO). Fifty-five compounds were synthesized and tested "in vitro" for their inhibitory effects on rat liver mitochondrial MAO. The most efficient MAO inhibitors were the benzylidene derivatives (sequence: see text] where R is the piperonyl radical and ethyl or isopropyl substituents are in R1 position. Correlation of MAO activity with hydrophobic, electronic and steric properties of tested compounds, evaluated by means of Quantum Mechanical calculations and calorimetric analysis (DSC) suggest that electronic and steric parameters give a better fit than hydrophobicity with the biological activity.