New NO-donors with antithrombotic and vasodilating activities, Part 21. Pseudonitrosites and other azodioxides with vicinal electron acceptors.

Twelve vicinally substituted nitro-nitroso compounds (pseudonitrosites) were synthesized, nine of them for the first time. In the solid state the dimeric azodioxides are present. In the class of the pseudonitrosites 2a-h, all compounds exhibited comparatively strong antiplatelet activity in vitro (Born test, collagen). Four of them showed an IC50 below 10 microM, 2a being the most active substance with an IC50 = 2.1 microM. When administered orally to rats (60 mg/kg) small antithrombotic effects were observed. The pseudonitrosite 6d was the most active compound (18% inhibition in arterioles). The in vitro decomposition of 2a at 37 degrees C gave NO and N2O, indicating that the above pharmacological effects were mediated by an NO-dependent mechanism. The replacement of the nitro group in the pseudonitrosite partial structure by other electron acceptors i.e. acetyl, carboxyl, or acetyloxy groups leads to inactive (10a) or less active compounds (10b, e).