Inhibition of Monoamine Oxidases by Functionalized Coumarin Derivatives: Biological Activities, QSARs, and 3D-QSARs

A large series of coumarin derivatives (71 compounds) were tested for their monoamine oxidase A and B (MAO-A and MAO-B) inhibitory activity. Most of the compounds acted preferentially on MAO-B with IC50 values in the micromolar to low-nanomolar range; high inhibitory activities toward MAO-A were also measured for sulfonic acid esters. The most active compound was 7-[(3,4-difluorobenzyl)oxy]-3,4-dimethylcoumarin, with an IC50 value toward MAO-B of 1.14 nM. A QSAR study of 7-X-benzyloxy meta-substituted 3,4-dimethylcoumarin derivatives acting on MAO-B yielded good statistical results (q2 = 0.72, r2 = 0.86), revealing the importance of lipophilic interactions in modulating the inhibition and excluding any dependence on electronic properties. CoMFA was performed on two data sets of MAO-A and MAO-B inhibitors. The GOLPE procedure, with variable selection criteria, was applied to improve the predictivity of the models and to facilitate the graphical interpretation of results.