Twenty-four new N-[(4-phenylpiperazin-1-yl)-methyl] derivatives of 3,3-diphenyl- (7-18) and 3-ethyl-3-methyl-pyrrolidine-2,5-dione (19-30) were synthesized and evaluated for their anticonvulsant activity in the maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurological toxicity was determined using the rotorod screen. Eleven compounds were active and revealed protection only in electrically induced seizures (MES). In the whole series the most effective compound was N-[{4-(3-trifluoromethylphenyl)-piperazin-1-yl}-methyl]-3,3-diphenyl-pyrrolidine-2,5-dione (14) with an ED(50) value of 30.3 mg/kg (p.o. rats) in the MES test. To explain the possible mechanism of action, for chosen active derivatives 7, 8, 9, 11, 14, 23, and 26, their influence on Na(V) 1.2 sodium channel currents was evaluated in vitro. The crystallographic structures for several molecules (8, 10, and 11) were solved.
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