Aim: Hypertension is a major health problem worldwide resulting in high death rates due to its consequences and complications. Therefore, searching for new vasorelaxants is a must to find new vasodilators efficient for the treatment of different cardiovascular diseases. Methodology: Different 6-phenyl-3-pyridazinone based derivatives were synthesized and screened for their vasorelaxant activity according to the reported method using hydralazine as a standard. Results: The tested compounds revealed potent to mild activity with EC50 values 0.339-114.300 μM compared with hydralazine EC50 = 18.210 μM. Conclusion: The most active compounds were the acid 5, its ester analog 4 and 4-methoxyphenylhydrazide derivative 10c (EC50 = 0.339, 1.225 and 1.204 μM, respectively). Therefore, 6-phenylpyridazin-3(2H)-one can be a hit for structural optimization to obtain promising vasorelaxants.
Keywords: 3-pyridazinone; hydralazine; vasorelaxant.