Study of interacting mechanism of amino acid and Alzheimer's drug using vibrational techniques and computational method

• Published in: Journal of molecular structure 2021-03, Vol.1227, p.129664, Article 129664
• Main Authors: Saikia, Jyotshna, Borah, Bhargab, Devi, Th. Gomti
• Format: Article
• Language: English
• Subjects: DFT; DL-Alanine; FTIR; Memantine; Raman
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2020.129664

•The geometrical optimization and frequency calculation of DL-Alanine, memantine and their interacting state are performed using B3LYP/ 6–311 ++ g (d, p).•The vibrational spectroscopic methods (FTIR and Raman) are used to record the experimental spectra of the molecules.•The different quantum chemical parameters, NLO properties and thermal properties of the molecules are reported.•The transfer of charge between DL-Alanine and memantine through NH•••O intermolecular hydrogen bond is observed.•Molecular docking study of DL-Alanine + memantine state against 6DG7 receptor shows  binding energy of −5.23 kcal/mol. The present work is undertaken to investigate the molecular interaction between Memantine (Alzheimer's drug) and DL-Alanine (amino acid) using DFT and vibrational spectroscopic methods, in particular, Fourier Transform Infrared Spectroscopy (FTIR) and Raman techniques. The DFT calculations of these molecules are carried out using the B3LYP/6–311 ++ G (d, p) level of theory. The experimental FTIR and Raman spectra of the molecules are compared to the respective DFT computed wavenumbers. A satisfactory agreement is obtained between experimental and computed wavenumbers. Further, HOMO-LUMO energy gap, Natural Bond Orbital (NBO) analysis, total energy, zero-point vibrational energy, Molecular Electrostatic Potential (MEP), chemical potential, hardness, ionization energy, global electrophilicity index, dipole moments, and first-order hyperpolarizabilities of the interacting state are reported and compared to the respective parameters of the individual states. The NBO analysis of the molecules indicates the transfer of charge between DL-Alanine and Memantine through NH•••O intermolecular hydrogen bonds. The molecular docking studies of the molecules are  performed to investigate the binding affinity of the ligand with the 6DG7 receptor. The interaction of DL-Alanine and Memantine is studied using DFT and vibrational techniques. The charge transfer mechanism between two biomolecules are studied and role of intermolecular hydrogen bond is discussed. The molecular docking analysis between the molecules and 6DG7 receptor is carried out to predict the best binding sites. [Display omitted]