COMBINED EXPERIMENTAL AND COMPUTATIONAL STUDY OF THE RADICAL SCAVENGING ACTIVITY OF LUTEOLIN

The luteolin has been extracted from Euphorbia schimperiana then H-1 NMR, C-13 NMR and 2D NMR spectra were measured. The ground-state geometries have been computed by using density functional theory (DFT) at B3LYP/6-31G* and M06/6-31++G** level of theories. The time dependent density functional theory (TD-DFT) has been applied to compute the absorption spectra with and without solvent. The absorption spectra have been computed in methanol to check the effect of solvent using the polarized continuum model (PCM). On the basis of bond dissociation enthalpy (BDE) and the adiabatic ionization potential (IP), we have explained the antioxidant activity of luteolin and its rotamer/positional isomer. Two mechanisms have been explained for the radical scavenging processes, i.e. hydrogen atom transfer and one-electron transfer.