Theoretical studies on the molecular basis of free radical scavenging mechanism and photoprotective potential of avenanthramides

Abstract

The research work presented in this thesis comprises a theoretical study of the structural, electronic, and antioxidant properties of the Avenanthramides derived from oats. Avenanthramides are open-chain compounds containing two aromatic rings of an anthranilic acid derivative and cinnamic acid derivative and both these rings are connected through an α,β-unsaturated amide linkage. For this purpose, eight Avenanthramides of interest are selected and the geometry-optimized structures of these compounds are utilized for all the reactivity investigations using density functional theory methods. The major aim of the work comprises the comparative investigation of the radical scavenging activity of the selected compound by its structural and electronic features. The potential ability of these compounds to quench different radicals was studied both by thermodynamic as well as kinetic aspects. For this purpose, the work explored several pathways within the mechanism proposed in the literature. The possibilities of various radical stabilization pathways are also studied using electronic parameters. Utilizing the thermodynamic cycle of the radical quenching process we expanded the ability of these compounds towards a pool of radical species. Moreover, the UV absorbance and UV filtering activity of the selected compounds were analyzed. The obtained UV filtering activity and radical quenching ability of these compounds especially caffeic acid-based compounds are found to exhibit excellent photoprotective ability.