Study of Isoniazid-Pyridoxine biomolecular complex using spectroscopic (Raman, SERS, FTIR, UV-vis) and quantum chemical calculation

Tuberculosis is one of the oldest recorded human diseases caused by Mycobacterium tuberculosis mainly affecting the lungs. Isoniazid is one of the most commonly used drugs for the treatment of tuberculosis. Pyridoxine is vitamin B6 which prevents the occurrence of peripheral neuropathy caused due to Isoniazid. In the current work, the structural and chemical parameters of the Isoniazid and Pyridoxine complex (IPC) are characterized using spectroscopic (Raman, FTIR and SERS) and DFT methods. The UV–vis spectroscopy is used to examine the IPC maximum absorption peak. The B3LYP/6-311++G(d,p) basis set is employed for calculating the molecular properties, theoretical frequencies and other quantum chemical parameters. The vibrational assignment of the theoretical spectra is obtained using VEDA software. The experimental and computed spectra are found to be in good agreement. The NBO analysis is done to evaluate the charge transfer taking place within the molecular system. The intramolecular and intermolecular hydrogen bond formation is identified by performing QTAIM analysis. Furthermore, the ability of IPC to act as a drug is confirmed by Bioactivity score and Drug Likeness analysis. Molecular docking study is carried out to determine the best binding conformer between the Isoniazid + Pyridoxine complex and 5FXS receptor.