Molecular structural, non-linear optical, second order perturbation and Fukui studies of Indole-3-Aldehyde using density functional calculations

Evaluation of experimental, computational, molecular docking and dynamic simulation of flucytosine

Flucytosine (5-fluorocytosine), a fluorine derivative of pyrimidine, has been studied both experimentally and quantum chemically. To obtain the optimized structure, vibrational frequencies and other various parameters, the B3LYP method with a 6-311++G(d,p) basis set was used. Atom-in-molecule theory was used to calculate the binding energies, ellipticity and isosurface projection by electron localization of the molecule (AIM). In addition, the computational results from IR and Raman were compared with the experimental spectra. NBO analysis was used to analyze the donor and acceptor interactions. To know the reactive region of the molecule, the molecular electrostatic potential (MEP) and Fukui functions were determined. The UV-Vis spectrum calculated by the TD-DFT/PCM method was also compared with the experimentally determined spectrum. The HOMO-LUMO energy outcomes proved that there was a good charge exchange occurring within the molecule. With DMSO and MeOH as the solvents, maps of the hole and electron density distribution (EDD and HDD) were produced in an excited state. An electrophilicity index parameter was looked at to theoretically test the bioactivity of the compound. To find the best ligand-protein interactions, molecular docking was also carried out with various receptor proteins. In order to verify the inhibitory potency for the receptor protein complex predicted by docking and molecular dynamic simulation studies, the binding free energy of the receptor protein complex was calculated. Using the MM/GBSA technique, we determined the docked complex's binding free energy. To confirm the molecule's drug similarity, a biological drug similarity investigation was also executed.Communicated by Ramaswamy H. Sarma.

Structural and vibrational investigations and molecular docking studies of a vinca alkoloid, vinorelbine

Vinorelbine, a vinca alkaloid, is an antimitotic drug that inhibits polymerisation process of tubulins to microtubules, and is widely used in cancer chemotherapy. Due to the importance of the structure-activity relationship, in this work the conformational preferences of the vinorelbine molecule were surched by PM3 method. The obtained lowest energy conformer was then optimized at DFT/B3LYP/6-31G(d,p) level of theory and the structural characteristics were determined. Frontier orbital (HOMO, LUMO) and molecular electrostatic potential (MEP) analyses were performed for the optimized structure. The experimental FT-IR, Raman and UV-VIS spectral data of vinorelbine along with the theoretical DFT/B3LYP/6-31G(d,p) calculations were investigated in detail. The vibrational wavenumbers were assigned based on the calculated potential energy distribution (PED) of the vibrational modes. To shed light into the anticancer property of vinorelbine as microtubule destabilizer, the most favourable binding mode and the interaction details between vinorelbine and tubulin were revealed by molecular docking studies of vinorelbine into the α,β-tubulin (PDB IDs: 4O2B; 1SA0; 7CNN) and binding free energies were calculated by the combination of Molecular Mechanics/Generalized Born Surface Area (MMGBSA) and Molecular Mechanics/Poisson-Boltzmann Surface Area (MM-PBSA) methods {MM/PB(GB)SA}. The calculated vinorelbine-7CNN binding free energy, using by MM/PB(GB)SA approach, was found to be the best (-50.39 kcal/mol), and followed by vinorelbine-4O2B (-28.5 kcal/mol) and vinorelbine-1SA0 (-17.59 kcal/mol) systems. Moreover, the interaction of vinorelbine with the cytochrome P450 enzymes (CYP), which are known to help in the metabolism of many drugs in the body, was investigated by docking studies against CYP2D6 and CYP3A4 targets.Communicated by Ramaswamy H. Sarma.

Quantum mechanical and spectroscopic (FT-IR, FT-Raman) study, NBO analysis, HOMO-LUMO, first order hyperpolarizability and molecular docking study of methyl[(3R)-3-(2-methylphenoxy)-3-phenylpropyl]amine by density functional method

Quantum chemical techniques such as density functional theory (DFT) have become a powerful tool in the investigation of the molecular structure and vibrational spectrum and are finding increasing use in application related to biological systems. The Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) techniques are employed to characterize the title compound. The vibrational frequencies were obtained by DFT/B3LYP calculations with 6-31G(d,p) and 6-311++G(d,p) as basis sets. The geometry of the title compound was optimized. The vibrational assignments and the calculation of Potential Energy Distribution (PED) were carried out using the Vibrational Energy Distribution Analysis (VEDA) software. Molecular electrostatic potential was calculated for the title compound to predict the reactive sites for electrophilic and nucleophilic attack. In addition, the first-order hyperpolarizability, HOMO and LUMO energies, Fukui function and NBO were computed. The thermodynamic properties of the title compound were calculated at different temperatures, revealing the correlations between heat capacity (C), entropy (S) and enthalpy changes (H) with temperatures. Molecular docking studies were also conducted as part of this study. The paper further explains the experimental results which are in line with the theoretical calculations and provide optimistic evidence through molecular docking that the title compound can act as a good antidepressant. It also provides sufficient justification for the title compound to be selected as a good candidate for further studies related to NLO properties.

Vibrational, UV spectra, NBO, first order hyperpolarizability and HOMO-LUMO analysis of carvedilol

In this work, we have investigated experimentally and theoretically on the molecular structure, vibrational spectra, UV spectral analysis and NBO studies of cardio-protective drug carvedilol. The FT-Raman and FT-IR spectra for carvedilol in the solid phase have been recorded in the region 4000-100 cm(-1) and 4000-400 cm(-1) respectively. Theoretical calculations were performed by using density functional theory (DFT) method at B3LYP/6-31G(d,p) and B3LYP/6-31++G(d,p) basis set levels. The harmonic vibrational frequencies, the optimized geometric parameters have been interpreted and compared with the reported experimental values. The complete vibrational assignments were performed on the basis of potential energy distribution (PED) of the vibrational modes. The thermodynamic properties and molecular electrostatic potential surfaces of the molecule were constructed. The electronic absorption spectrum was recorded in the region 400-200 nm and electronic properties such as HOMO and LUMO energies were calculated. The stability of the molecule arising from hyper conjugative interactions and charge delocalization have been analyzed from natural bond orbital (NBO) analysis. The first order hyperpolarizability of the title molecule was also calculated. The photo stability of carvedilol under different storage conditions were analyzed using UV-Vis spectral technique.

Computational studies on the anastrozole and letrozole, effective chemotherapy drugs against breast cancer

In this paper, computational studies were carried out on anastrozole and letrozole, chemotherapy drugs used against breast cancer. Optimization and frequency calculations were performed at B3LYP/6-31G (d) basis set and vibrational frequencies were assignment. Single point calculations were performed at DFT method with a hybrid functional B3LYP/6-311G (d, p) basis set. Theoretical NMR data were obtained at DFT method with a hybrid functional B3LYP/6-311G++ (2d, p) with GIAO (Gauge-Independent Atomic Orbital). IEF-PCM method was used as solvation model. NBO calculations were performed by the same basis set and calculation method with single point calculation. Global and localized reactivity parameters; fukui indices (f) chemical hardness (η), softness (S), chemical potential (μ), electronegativity (χ) and electrophilicity index (ω) were calculated. All computational parameters were compared with the experimental results obtained from the literature.