Computational Study of the Antioxidative Potential of Substituted Hydroxy-2-arylbenzothiazole Derivatives

Abstract

This study use density functional theory B3LYP/6-31+G(d) methods to examine theoretically the electrical and structural characteristics of substituted hydroxy-2-arylbenzothiazole derivatives, which contribute to their ability to scavenge free radicals. It was found that the antioxidant activities increase with small the energy gap ΔE (EL-EH), lower ionization potential (IP), lower hardness (η), higher softness (S), higher dipole moment, higher negative total energy of optimization and high the net charge. These values are interpreted with experimental equivalent antioxidant values. Two series of compounds, series one, compounds 1-6 (hydroxyl groups attached to aryl ring) and series two viz. compounds 7-10 (substituent to ortho-position of phenyl ring) were studied. It was observed that in series one, compound 6 with three hydroxy substituent had the lowest energy gap ΔE, lowest IP, lowest hardness (η), highest softness (S), highest dipole moment, highest total negative energy of optimization and compound 1 with no substituent had highest energy gap ΔE, highest IP, highest hardness (η), lowest softness (S), lowest dipole moment, lowest negative total energy of optimization. The results of the antioxidant activity are in the following order: 6 > 5 > 4 > 2 > 3 > 1. The introduction of the strongly electron-withdrawing substituent, –NO2 and –CN groups attached to phenyl ring of hydroxy-2-arylbenzothiazole nucleus improve the effect of antioxidant activity. On the basis of these findings, a novel antioxidant compound that possesses enhanced activity can be developed.