Exploring non-covalent interactions between caffeine and ascorbic acid: their significance in the physical chemistry of drug efficacy

Drug-drug interactions occur when two or more molecules interact, potentially altering their effectiveness and cause adverse effect to human health. Caffeine is known to interact with many other drug molecules. Our study was designed to shed insights on characteristics of non-covalent interaction (NCI) and quantify the prevalence of drug-drug interaction between the caffeine and ascorbic acid molecule in gas phase and solvent phase (water) using Density Functional Theory. It was found that caffeine and ascorbic acid molecules interact with one another through hydrogen bonds (HBs) in various ways which can be deduced from the optimized structures and the resulting calculation of binding energy was observed -14.65 kcal/mol and -11.62 kcal/mol in gas and water phase respectively. The Natural Bond Orbital analysis confirmed that the highest stabilization energy interactions are the same interactions which are found to be the possible hydrogen bonds. The RDG, AIM, LED analyses confirmed the delocalisation and localisation of the electron in the complex. The understanding of the non-covalent interaction between caffeine and ascorbic acid may help to further study the drug effectiveness and drug delivery systems.