Abstract: In searching for effective anticonvulsant agents, fourteen 6-aryl-4.5-dihydro-3(2H) pyridazinones. Fifteen 6-aryl-3(2H) pyridazinones, and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized, and evaluated in mice for the ability to antagonize maximal electroshock seizure (MES). The ED50 values showed that 6-(2',4'-dichlorophenyt)-3(2H) pyridazinone was the most potent anticonvulsant among these corn- pounds (ED50 = 10.15 mg/kg). The structure-activity relationships of the aryl pyridazinones were studied. The result showed that: (1)the higher the value of the hydrophobic parameter л of the substituent on the phenyl ring. The more potent the anticonvulsant activity of the cornpound. And (2) only the compounds with an electron withdrawing substituent on the phenyl ring exhibited appreciable anticonvulsant activity.

Key words: Aryl pyridazinones, 3-GABA-6-aryl pyridazines, Anticonvulsant activity, Structure-activity relationships