Interação teórica da ciclodextrina com moléculas de óleos essenciais.

Abstract

Essential oil molecules have broad nutritional and medical applicability. However, these applications are restricted due to the non-polarity and high volatility. One way to overcome these limitations is through the use of inclusion complexes. Cyclodextrin is a sugar complex widely used to prepare inclusion complexes and plays an important role in delivering these low-volatility molecules with improved solubility in specific solutions. This study investigated the physicochemical properties involved in the interaction and the formation of complexes of fourteen essential oil molecules through ab-initio and semi-empirical theoretical calculations in computational chemistry, including Carvacrol, Menthol, Limonene, Phytol, and Citronellal. The Gaussian 09 program was used for structure optimization and determination of the most stable coordinates, while the Abalone program with the AMBER force field was used for encapsulation. The PM6 and wxb97xd functionals were employed to calculate interaction energies in solvent-free, explicit water, and explicit ethanol environments. It was observed that orbital localization, energy interaction, and hydrogen bonding play an important role in forming inclusion complexes between essential oil molecules and cyclodextrin with favorable stability. Molecules with OH substituents formed hydrogen bonds with cyclodextrin. The solvent used also demonstrated an influence on the complex, particularly on the frontier orbitals HOMO and LUMO, aiding in encapsulation and more stable interactions. Additionally, open-chain molecules showed a remarkable interaction with the host macromolecule. The results obtained from theoretical calculations helped to understand why some essential oil molecules interact better with cyclodextrin to form inclusion complexes.