Quinolizidinyl-benzimidazoles as platelet-antiaggregating agents

Two series of ()-2-phenyl-1-(quinolizidin-1α-yl)benzimidazoles, 12A–26A, and ()-2-phenyl-1- (quinolizidin-1β-yl)benzimidazoles, 12B–26B, were prepared and tested for the inhibition of human platelets aggregation induced by ADP, collagen, and adrenaline. All epimers A, i.e., 12A–26A, were devoid of any activity against the three agonists, while the epimers B, i.e., 12B–26B, exhibited different degrees of activity, though practically confined against the ADP-induced aggregation. The best compounds were 19B, 24B, and 26B, which inhibited for 69–67% at 260 μM and for 40–29% at 65 μM concentration the ADP (2 μM)-induced aggregation. The observed agonist and spatial structure selectivity warrant further investigations of this kind of benzimidazole derivatives.