Molecular interaction studies of antituberculosis drug Isoniazid in aq. β-cyclodextrin solution: A volumetric, spectroscopic and molecular docking approach

Abstract

Volumetric and compressibility investigations are crucial to understanding the molecular interactions prevailing between various components of solutions. At distinct temperatures and ambient pressure (P = 0.1 MPa), the effect of β-cyclodextrin on the antituberculosis drug Isoniazid (INH) was studied at concentrations ranging from 0.0304-0.2698 mol.kg−1. Some thermodynamic properties of the drug Isoniazid, viz., limiting apparent molar volume and limiting compressibility (V°ϕ and K°S,ϕ) are derived from the appropriate density (ρ) and ultrasonic velocity (u) data, with experimental slopes Sv and Sk describing solute–solute interactional parameters at infinite dilution. Furthermore, transfer properties of drug, such as limiting transfer volume (ΔtrV°ϕ) and limiting transfer compressibility (Δtr K°S,ϕ) of drug, reveal key information regarding the interaction of drug with a solvent or a cosolute. The hydration number (nH) was computed to figure out the hydration behaviour of the studied drug in both the mediums. The encapsulation of isoniazid drug in the hydrophobic region of cosolute (β-cyclodextrin) in the solution phase was evaluated using 1H NMR titration. Additionally, theoretical molecular docking was employed to determine the possible conformation and binding energy of the non-covalent inclusion complex.