Investigating the intermolecular interactions in the explicitly solvated complexes of lomustine with water and ethanol

Abstract

Lomustine is an alkylating chemotherapy drug that is used to treat diverse types of cancer, including brain tumors, Hodgkin's lymphoma, and non-Hodgkin's lymphoma, which works by interfering with the DNA in cancer cells, preventing them from dividing and growing. As such the lipid bilayer of the cell and body fluids provides the environments in which lomustine (lmt) performs its biological function. Chemical reactions involving biological systems occur in the liquid phase, where accurate modeling of the reaction pathways considers the influence of the solvent used. Implicit solvation adequately accounts for these effects but falls short when evaluating solvent-solute interactions. This study aims to explore the structures, thermodynamics, reactivity, UV–vis spectroscopy, energy decomposition analysis, and the interaction energies of lmt with molecules of water and ethanol (n = 1, 2, and 3), using density functional theory (DFT) at the ωB97XD/6–311++G (d, p) level of theory. The thermodynamics results reveal that the polarity of water molecules significantly influences the interaction strength of the studied systems as the interaction observed between lmt with W1, Et1, and Et2 is feasible and spontaneous, compared to others. The stability of the different clusters depends on the intermolecular hydrogen bonds formed between the drug and the polar solvent as explicated by the H-bond interaction distance. Also, the interaction of lmt with each of the solvents causes a slight deformation in the geometry of the lmt, moreover, the reactivity descriptors predicted the interaction of lmt to increase with a corresponding increase in the addition of water molecules.