Structural Characterization, In Silico Studies and In Vitro Antibacterial Evaluation of a Furanoflavonoid from Karanj

Abstract

Pongamia pinnata, popularly referred to as Karanj, is a multipurpose legume well known for its traditional and pharmacological properties with an efficient remedy for human health problems. Karanjin, a furanoflavonoid (3-methoxy-2-phenylfuro [2,3-h] chromen-4-one), is the main constituent of Karanj seeds with important biological attributes. The present investigation was aimed at standardizing a process for the isolation of karanjin from seed oil with an emphasis on achieving a higher yield of the pure compound. Structural elucidation and characterization were carried out via HRMS, Fourier transform infrared spectroscopy, X-rays diffraction, NMR, Raman spectroscopy, and thermogravimetric studies. The optimized geometry of the karanjin compound has been determined by a density functional theory and compared with experimental values, which are in excellent agreement. The potency of karanjin against pathogenic indicators was evaluated and confirmed by Raman scattering and field emission scanning electron microscopy imaging. The physicochemical parameters of karanjin were determined by in silico drug likeness properties, and molecular docking was also performed, which revealed the potential of karanjin as a highly functionalized and medicinally useful compound. From the docked conformations, the carbonyl group, 3-methoxy group, and oxygen atom in the C ring of the karanjin molecule were found to be biologically important for hydrogen bond formation with common bacterial enzymes involved in fatty acid biosynthesis. The mode of antibacterial action of karanjin revealed the complex patterns of probable cell wall disruption. This is the first report with regard to karanjin characterization and theoretical calculations of a density functional theory and its utility as a potential pharmacophore depicting an antibacterial property using Raman spectroscopy and docking studies.