Molecular Insight into the Ternary Complex Formation between Ethambutol, Isoniazid and β‐Cyclodextrin.

Long term intake of antituberculosis drugs will lead to severe adverse reactions that will ultimately deteriorate a patient's health and well‐being. With that, the ternary inclusion complex was explored, whereby β‐cyclodextrin (β‐CD) was chosen as the supramolecular host carrier to accommodate two kinds of first line antituberculosis guest drug molecules simultaneously, namely isoniazid (INH) and ethambutol (ETB) which would provide many therapeutic benefits. The inclusion complex of β‐CD/INH/ETB was prepared using solvent evaporation method. Fourier transform infrared spectroscopy (FT‐IR), proton nuclear magnetic resonance spectroscopy (1H‐NMR), and 2‐dimensional nuclear Overhauser effect spectroscopy (2D‐NOESY) NMR were used to investigate the functional groups and structure of the complex. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were employed to study the surface morphology and crystallinity changes during complex formation. Thermogravimetric analysis (TGA) was performed to investigate the thermal properties of the complex. FT‐IR and both types of NMR results had revealed the successful penetration of both the drug molecules into the β‐CD cavity. SEM images and XRD spectra had shown a drastic change in surface structure and reduction in crystallinity during complex formation, which had indicated successful formation of a new compound. TGA had proven that the complex had significantly greater thermal stability as compared to the pure components. Molecular dynamics (MD) and molecular docking simulations were also performed to understand the molecular interaction between β‐CD, INH, and ETB. Through precise calculations of interaction and binding energies, β‐CD/INH/ETB was found to be a more stable inclusion complex compared to the binary β‐CD/INH and β‐CD/ETB complexes. [ABSTRACT FROM AUTHOR]