Anti-oxidation properties of 2-substituted furan derivatives: A mechanistic study

Abstract

2-(p-phenyl substituted styryl)-furans were synthesized and studied the excited state and anti oxidation properties using absorption, fluorescence, density functional theory and DPPH radical scavenging assay. 2-(p-hydroxy phenyl styryl)-furan (6) exhibits good antioxidant properties with IC50 ~ 40 μM as compared to the amine, chloro, cyano methoxy and nitro substituted styryl compounds (1–5, 7–8) (IC50 > 150 μM). It is shown that furans 1–3 with strong electron withdrawing nitro, cyano and chloro substituent do not show antioxidant properties. The O–H bond dissociation energy (BDE) of p-hydroxy substituted furan compound is comparable to the BDE of vitamin E. The antioxidant activity of furan compound is further reduced with increasing the dipolar nature of the molecule. From the thermodynamic parameters and antioxidant properties, it is shown that there is a correlation of antioxidant properties with the ground state dipole moment, X–H bond dissociation energy (X: O; N) and proton affinity (PA). In presence of the furan compound, the quenching of DPPH radical is occurred predominantly through hydrogen atom transfer mechanism.