RESUMO
A series of coumarin derivatives 6-8, 9a-h, 11 and 13a, b -16a, b was synthesized and screened for their anticonvulsant profile. Screening of these analogues using the 'gold standard methods' revealed variable anticonvulsant potential with remarkable effects observed particularly in chemically-induced seizure test. Compounds 6, 7, 13b disclosed the highest potency among the series with 100% protection against scPTZ. Quantification study confirmed that compound 6 (ED50 0.238 mmol/kg) was the most active congener in the scPTZ model and was approximately 1.5 folds more potent than ethosuximide as reference drug Meanwhile, in the MES test, candidate drugs exhibited mild to moderate anticonvulsant efficacy, the highest of which was compound 14a, imparting 50% protection at 2.1 mmol/kg, followed by other compounds with activity ranging from 14 to 33%, as compared to diphenylhydantoin. Additionally, all candidate compounds were screened for acute neurotoxicity using the rotarod method to identify motor impairment, where almost all compounds passed the test. Further neurochemical investigation was performed to unravel the effect of the most active compound (6) on GABA level in mouse brain, where a significant elevation was evident by 4 and 1.4 folds with respect to that of the control and reference groups at p < 0.05. Molecular modeling study using Discovery Studio program was performed, where compound 6 exhibited good binding interaction with γ-aminobutyric acid aminotransferase (GABA-AT) enzyme and this was consistent with the attained experimental results.
