Spectroscopic, quantum chemical, hydrogen bonding, reduced density gradient analysis and anti-inflammatory activity study on piper amide alkaloid piperine and wisanine

Abstract

A combined experimental and theoretical quantum chemical calculations have been carried out to study the geometry, vibrational wavenumbers, electronic transition and anti-inflammatory activity of piper amide alkaloid compound piperine (PP). Computational study is done on other piper amide alkaloid wisanine (WS) using B3LYP/6–311G(d,p) basis set. The conformational analysis is carried out to find the most stable geometry of PP and WS. Normal coordinate analysis (NCA) is performed to analyse the vibrational wavenumber and potential energy distribution (PED) assignments. The interaction of PP and WS with water molecule is also performed to know the effect of hydrogen bond on its geometry and vibrational spectra. Natural bond orbital (NBO) analysis was performed to study the charge delocalization, hyperconjugative interaction, inter and intramolecular hydrogen bonding interaction in the molecule to know about anti-inflammatory active site. Non-covalent interactions are analyzed using reduced density gradient (RDG) analysis. The UV–visible spectrum of PP in ethanol and water solvent is recorded and compared with calculated data. The 1H and 13C NMR spectra of PP are recorded and analyzed. The chemical stability and anti-inflammatory activity of title compound are evaluated by HOMO-LUMO analysis. The chemical reactivity descriptors are calculated to predict the reactivity and stability of the molecule. The intermolecular interactions and crystal packing of title compound are studied by Hirshfeld surface analysis techniques. PP is screened for its anti-inflammatory activity. Molecular docking study predicts the binding site of PP and WS into its target protein.