New NO-donors with antithrombotic activities and vasodilating activities, III: 3,4-disubstituted N-nitroso-5-sydnone imines.

38 title compounds have been synthesized. They bear a wide variety in substituents including alkyl-, aryl-, arylalkyl-, and styryl groups. The anti-platelet activities elucidated in the Born-test with collagen cover more than two orders of magnitude (IC50 = 0.3-45 mumol/L). These effects depend on the presence of the N-NO-group. This is shown by comparison with the corresponding sydnone imines, sydnone cyanimines, and sydnones. The most suitable substituents were phenylethyl, styryl, and hexyl at either position of the molecule. Seven compounds, most of them styryl derivatives, have IC50 values below 1 mumol/L. It is suggested that the differences in activity are connected with the ability of the compounds to bind to the platelet membrane.