Influence of aqueous extract of Arjuna (Terminalia arjuna) on growth and antioxidant defense system of human hepatoma cell line (HepG2)

Abstract

Arjuna (Terminalia arjuna) is a common medicinal plant used in the ayurvedic system of medicine to treat various ailments and is one of the active ingredients in many polyherbal hepatoprotective formulations currently used in India. Despite its extensive usage, data on its ability to modulate basal oxidative markers in cell models are limited. Hence in the present study we have addressed whether aqueous extract of Arjuna possess the propensity to modulate endogenous oxidative markers in HepG2 cells. Cells were incubated with aqueous extract of Arjuna (1, 5, 10, 25 and 100 µg/ml) for varied time points (4, 8, 12, 16, 20 and 24 h) and biochemical markers of oxidative stress in cell lysate were determined. Cells incubated with Arjuna showed no significant effect in terms of cytotoxicity or cell proliferation upto 100 µg/ml concentrations. However, incubation with Arjuna for 24 h showed diminution in the levels of lipid hydroperoxide (18-42%) and reactive oxygen species (11-29%) in cell cytosol. The antioxidant capacity (19-31%) of cells and levels of reduced glutathione (18-32%) was also found to be significantly increased. Interestingly, aqueous extract of Arjuna also enhanced activities of endogenous antioxidant enzymes (superoxide dismutase, 25-41%; catalase, 39-50%; glutathione peroxidase, 20-35%; glutathione reductase, 26-35% and glutathione transferase, 12-30%). Taken together, these data suggest that Arjuna has the propensity to improve endogenous antioxidant levels and reduce basal oxidative stress in HepG2 cells and indicates its potential as antioxidant and hepatoprotective adjuvant to combat oxidative stress in vivo. Key words: Arjuna, Terminalia arjuna, oxidative stress, antioxidant, HepG2, Hepatoprotection