Theoretical investigation on the interaction between Metformin and Ferulic acid - A DFT approach

We have theoretically studied the interaction of a commonly used drug, Metformin, with the herb, Ferulic acid, applying density functional theory (DFT). The complex was optimized at various positions and confirmed to be in their local minima through vibrational analysis at B3LYP/6 -311++G** level. Study on the molecular geometry along with the interaction energy of the complexes confirmed the presence of interaction between the hydroxyl and amine group of the herb and drug respectively. The calculation of Gibbs free energy and entropy exhibited the stability of the interacting structures along with the vibrational assignment which showed significant red and blue shifts in the complexes. Additionally, NBO analysis and molecular electrostatic potential (MEP) revealed the charge transfer between the complexes identifying an electrostatic interaction prevailing between the herb and drug.