Synthesis of 4 – aryl substituted semicarbazones and their terpenes derivatives : A newer scaffold as an anticonvulsant agents

A series of 4 – aryl substituted semicarbazones of some terpenes ie , citral ( acyclic terpene ) , camphor ( bicyclic terpene ) and menthone ( monocyclic terpene ) were synthesized from substituted anilines , to meet the structural requirements essential for anticonvulsant activity . The structures of the synthesized terpene semicarbazones were confirmed by I.R. , H-NMR and elemental analysis. The synthesized semicarbazone derivatives were evaluated for anticonvulsant and sedative – hypnotic activity . After intraperitoneal injection to mice , the semicarbazone derivatives were examined by three chemoshock models for a single dose study . These three chemoshock model includes were , Isoniazid ( INH ) induced convulsion model , Thiosemicarbazide ( TSC ) induced convulsion model and 4 – aminopyridine ( 4-AMP ) induced convulsion model . All the synthesized semicarbazone derivatives were also evaluated for neurotoxicity ( N T ) screen by rotorod test and sedative – hypnotic activity by using pentobarbitone induced narcosis model . All the compounds showed anticonvulsant activity in one or more test models . The preliminary result showed that all of the tested compounds were protective against INH and TSC screen at a dose of 30 mg kg -1 at 0.5 h. Compounds ( 2a, 4a and 4c ) were found to be most active against INH screen at a dose of 30 mg kg showed prolonged duration of action for 4h . compound 4c showed prolong activity at a dose of 30 mg kg against TSC screen . In 4 – AMP screen all of the compounds except (2a , 4a and 4c ) exhibited proconvulsion rather protection at a dose of 30mg kg at 0.5 h. , they potentiate the convulsion at a dose of 30 mg kg . None of the compound was found to be neurotoxic at a dose of 30 mg kg . Compound 4c showed most sedative activity in pentobarbitone induced narcosis model . compound 4a was found to be most potent anticonvulsant that showed activity in all sreens with no neurotoxicity and no sedative – hypnotic activity . In conclusion semicarbazones with terpenoid as the lipophilic moiety resulted in compounds with broad spectrum of anticonvulsant activity and therefore, they may be utilized for the future development of novel anticonvulsants with broad spectrum of anticonvulsant activity with no neurotoxicity and lesser sedative – hypnotic activity .