The effect of 18-crown-6 ether as nano carrier on the rate of intramolecular lactamization of gabapentin drug

Crown ethers with unique structures can transported across membranes and used as drug carriers. In this research the effect of 18-crown-6 ether as nano carrier on the rate of intramolecular lactamization of gabapentin drug has been studied at the MN15-L/6-31G* level of theory. Crossover temperatures computed from the vibrational frequencies of saddle points indicate that the nucleophilic attack by the amine functionality at the neighboring carbonyl moiety step is dominated by deep quantum tunneling while the dehydration step is dominated by shallow tunneling. According to the suggested mechanisms, degradation of gabapentin in the absence and presence of crown ether is in the steady-state regime. The nucleophilic attack step is endothermic and non-spontaneous while the dehydration step is exothermic and spontaneous. Decreasing of the equilibrium constant of the nucleophilic attack step and an increase in the activation energy of the dehydration step by 12.38 kJ/mol in the presence of crown ether lead to a retarding of the reaction rate of gabapentin degradation. 18-Crown-6 crown ether can be considered as a nanocarrier of gabapentin.