Spectroscopic (FT-IR, FT-Raman, UV–Vis), quantum chemical calculation and molecular docking evaluation of liquiritigenin: an influenza A (H1N1) neuraminidase inhibitor

Abstract

The vibrational spectroscopic analysis of anti-influenza agent liquiritigenin (LGN) was performed using Fourier-transform infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra. The experimental values of the LGN molecule was compared with vibrational frequencies obtained from the quantum chemical calculations using density functional theory (DFT) method employing 6-31G, 6-31G(d,p) and 6-311G(d,p) basis sets with scaled frequency, and these values are in good agreement with the computational one. The time-dependent density functional theory method was employed to compute the HOMO–LUMO energy gap of the LGN molecule and their differences were compared with transitions of UV-absorption spectra. The reactivity and selectivity of LGN were analyzed using parameters such as molecular electrostatic potential, global reactivity descriptors, Fukui functions and natural bond orbitals. The molecular orbital contributions were considered using the total, partial and overlap population density of states. The suitability of a drug candidate for human intake can be evaluated by absorption, distribution, metabolism, excretion and toxicity (ADMET) properties. The drug likeness and toxicity properties of LGN were confirmed with Lipinski’s rule of five and ADMET properties, respectively. The LGN molecule exhibits good bioactive score and less toxicity. A molecular docking analysis of LGN was carried out with influenza neuraminidase enzyme, and these results show that LGN has lowest binding affinity with inhibition constant when present in the active site.