[Synthesis and antiplatelet activity of 2-amino-4,5-diphenylthiazole derivatives].

A series of 4,5-diphenylthiazoles containing morpholinoalkyl amino groups at the 2 position was synthesized and their anti-platelet activities were evaluated. The inhibitory effects of the compounds in which phenyl groups at the 4 position were substituted by methoxy groups were more potent than those of aspirin and ibuprofen on the collagen-induced rabbit platelet aggregation. These compounds were also shown to have potent efficacies on the arachidonic acid-induced platelet aggregation. On the other hand, these compounds did not affect the ADP-induced platelet aggregation similarly to non-steroidal anti-inflammatory agents. Moreover, their efficacies on the inhibition of prostaglandin synthesis were more potent than that of ibuprofen. Therefore, we thought that 2-(morpholinoalkyl)amino-4,5-diphenylthiazoles, in spite of their basic properties, inhibited the platelet aggregation based on cyclooxygenase.