Comparative Hepatoprotective Effects of Esculetin and Its Derivatives Against Oxidative Stress

In this study, we evaluated the antioxidant activities of esculetin and four synthesized derivatives (E1, 2-oxo-2H-1-benzopyran-6,7-diyl diacetate; E2, 7-hydroxy-2-oxo-2H-1-benzopyran-6-yl acetate; E3, 7-(methoxymethoxy)-2-oxo-2H-1-benzopyran-6-yl acetate; E4, 7-hydroxy-2-oxo-2H-1-benzopyran-6-yl 2,4-dinitrobenzene-1-sulfonate) against oxidative stress in hepatocytes. In HepG2 cells, treatment with 1 mM tert-butyl hydroperoxide (TBHP) reduced cell viability to 40%, while co-treatment with esculetin restored cell viability. Among the esculetin derivatives, E2 exhibited the most significant cytoprotective effect, while E4 showed the lowest. Furthermore, E2 at 25 µM concentration showed the similar effects to esculetin in reducing ROS generation and preventing glutathione depletion. The treatment of E2 also enhanced the expression of HO-1 and GCLC proteins against oxidative stress. On the other hand, TBHP-induced oxidative stress decreased antioxidant activities including glutathione reductase, glutathione peroxidase, and catalase; however, E2 significantly increased these antioxidant activities. These findings suggest that the esculetin derivative, particularly E2, possesses potential as an antioxidant aimed at enhancing physiological functions.