Investigation of interaction of vanillin with Alpha, Beta and Gamma-cyclodextrin as drug delivery carriers: brief report

The aim of this study was to investigate interaction between vanillin and alpha-, beta- and gamma-cyclodextrin carriers for targeted drug delivery and compare the performance between them using theoretical methods. All theoretical calculations were performed on a Intel® Core™ i5 Processors computer at Kerman University using Gaussian 09 program package (Gaussian, Inc., Wallingford, USA) in a three month period (February 2014 to May 2014). Starting geometries were generated employing GaussView software, version 5 (Gaussian, Inc., Wallingford, USA) and then the resulting coordinates were optimized using density functional theory (DFT) calculations. The natural bond orbital method (NBO program, under Gaussian 09 program package) was carried out to study charge transfer energy associated with the intermolecular interactions. The quantum theory of atoms in molecules was applied for DFT results to get insight in the nature of interaction existing in the investigated systems. The calculations were carried out with AIM2000 program and AIMAll 14.10.27 package (Todd A. Keith, TK Gristmill software, Overland Park KS, USA) to find and characterize bond critical points. The vanillin molecule is adsorbed on the surface of carriers by hydrogen bonding between its oxygen atom and hydrogen atoms of cyclodextrin. The hydrogen of -OH group on the cyclodextrin can form hydrogen bond to the oxygen atom of carbonyl group of vanillin molecule. This study indicates a decrease of total energy with increasing surface of cyclodextrin. So gamma-cyclodextrin and its complex with the maximum surface in between carriers have the highest stabilities. The gamma-cyclodextrin shows the strongest interaction with vanillin. In all complexes of vanillin-cyclodextrin, the direction of charge transfer is from drug to carrier. Due to the high solubility of gamma-cyclodxtrin and its stronger interaction with the molecule vanillin, it can be the best option as drug carrier.