N-(benzyloxycarbonyl)glycine esters and amides as new anticonvulsants

Glycine is a small neutral amino acid exhibiting weak anticonvulsant activities in vivo. Recently, studies have demonstrated that N-(benzyloxycarbonyl)glycine (1) antagonized seizures superior to glycine in addition to activity in the maximal electroshock (MES) test, a convulsive model where glycine is inactive. In the present study a series of ester and amide derivatives of 1 as well as esters of N-(3-phenylpropanoyl)glycine (5) have been prepared. The compounds were evaluated in the MES test as well as in several chemically induced seizure models. Among the derivatives investigated, N-(benzyloxycarbonyl)glycine benzylamide (16) was the most potent compound exhibiting an anticonvulsant activity in the MES test comparable to the drug phenytoin. Median effective doses (ED50) of 4.8 and 11.6 mg/kg were determined at 30 min and 3 h after i.p. administration, respectively. Compound 16 also effectively suppressed tonic seizures in different chemically induced models such as the strychnine, 3-mercaptopropionic acid, and pentylenetetrazole tests. Moreover, the compound studied here did not show acute neurotoxicity in the rotorod test up to a dose of 150 mg/kg. It is concluded that N-(benzyloxycarbonyl)glycine amides, especially 16, are potent anticonvulsant agents.