Synthesis and inhibitory activities on platelet aggregation of some flavonoid analogues.

A series of 26 benzodioxan and benzodioxol derivatives of flavone have been prepared. The activity of the compounds on washed human platelet aggregation induced by adenosine diphosphate (ADP, 5 mumol/l), collagen (10 micrograms/ml) and calcimycin (20 mumol/l) was evaluated. The alkoxycarbonyl side chain derivatives inhibited all three types of aggregation inducers. Among the tested compounds Ia is the most potent inhibitor of collagen-induced aggregation but possesses a weak activity against the other two used inducers. The esters IIIb and in particular, IIIc are active against all the three used inducers. These results suggest that ethoxycarbonyl group is a potent substituent to provide the antiplatelet action in this series of flavonoids.