Tautomers of Ethosuximide and their Interaction with Calcium Cation - A DFT Treatment

Abstract

Ethosuximide is an imide which is often used in the treatment of typical epilepsy. Ethosuximide affects neuronal excitability by blocking T-type calcium channels. It may exhibit 1,3-type tautomerism (amide-iminol type tautomerism). All those possible tautomeric forms are considered. Additionally, interactions of those tautomers with calcium cation have been investigated. All the calculations have been performed within the realm of density functional theory with the constraints of B3LYP/6-311++G(d,p) level. The tautomers and their composites with calcium cation are found to be electronically stable and thermodynamically favorable structures. Ethosuximide tautomers have relatively much lower Boltzman distributions compared to ethosuximide. However, they form electronically stable and thermodynamically favorable composites with calcium cation. Also some quantum chemical and spectral properties of those systems have been obtained and discussed.