Synthesis and in vitro antiplatelet activity of new 4-(1-piperazinyl)coumarin derivatives. Human platelet phosphodiesterase 3 inhibitory properties of the two most effective compounds described and molecular modeling study on their interactions with phosphodiesterase 3A catalytic site

The synthesis and in vitro antiplatelet activity significant data of coumarin derivatives 5i-x and quinolin- 2(1H)-one derivatives 22a,b, as well as the corresponding structure-activity relationships are described. The recently reported 8-methyl-4-(1-piperazinyl)-7-(3-pyridylmethoxy)coumarin 5f and its potent 7-(2- morpholinoethoxy)-substituted new analogue 5u were notably more effective inhibitors of pure human platelet PDE3 than milrinone and cilostazol: these data were related, through a molecular modeling study, with the molecular interactions of the four compounds with the human PDE3A catalytic site.