CORRELATION BETWEEN MONOAMINO OXIDASE INHIBITOR ACTIVITY OF SOME THIAZOL-2-YLHYDRAZINES AND THEIR INTERACTION WITH DIPALMITOYLPHOSPHATIDYLCHOLINE LIPOSOMES

A calorimetric investigation has been carried out on the influence exe rted by some 1-(alkoxybenzoyl)-2-(4-substituted thiazolyl-2-yl)hydrazi nes, possessing monoamine oxidase inhibitory (MAOI) activity, on the t hermotropic behavior of model membranes constituted by dipalmitoylphos phatidylcholine (DPPC) vesicles. Attention was paid to evaluate how st ructural variations of drugs may influence drug-lipid interaction. The examined drugs were found to modify the gel to liquid-crystal phase t ransition of DPPC liposomes, by causing a shift of the transition temp erature (Tm-) toward lower values and a negligible variation in the en thalpy changes(Delta H). The different effects on DPPC thermotropic be havior of these MAOI drugs could be considered in terms of different s ubstituents on the molecule's backbone. The calorimetric results were related to drug's MAO inhibitory activity measured by fluorescence tec hniques and the apparent distribution coefficient of the compounds in water/n-octanol. A hypothesis on a correlation between a drug's struct ure, inhibitory activity, and membrane interaction has been suggested.