Density functional theory analysis of electronic properties correlated with the biological activities of naturally occurring biomolecular system: Isodihydrocadambine

Abstract

The atomic charge distribution, dipole moment, highest occupied-lowest unoccupied molecular orbital energy band gap, molecular electrostatic potential surface (MESP), UV–Visible spectra and (1H, 13C) chemical shifts in NMR spectra using density functional theory at B3LYP/6–31 + G(d,p) hybrid functional-basis set combination have been calculated in the case of Isodihydrocadambine (C27H34N2O10) which is reportedly biologically active natural compound. The molecular docking has also been performed to predict the expected biological activities of this bio-molecule and an attempt has been made to correlate the investigated electronic properties with the spontaneously originated bioactivity within it. The total dipole moment ≈ 2.02debye; reasonably low HOMO−LUMO energy band gap (≈3.89 eV) and MESP surface to be a chemically reactive site suited for drug activity have been observed in this bio molecule. The theoretical NMR spectroscopic characteristics agree with their experimentally evaluated values. The highest peak in UV–visible spectra has been calculated to be occurred at 284 nm arising due to HOMO-2 → LUMO + 2, HOMO-1 → LUMO + 1, HOMO → LUMO + 1, HOMO → LUMO + 2 electronic transitions. This bio molecule has been screened for the binding with the variety of protein receptors (1GCN, 2NMO and 3I40) which reveals that it possesses multifarious biological activity correlated with the behavior of its MESP surface and HOMO−LUMO band gap.