The antioxidant and cytoprotective activity of Ocimum gratissimum extracts against hydrogen peroxide-induced toxicity in human HepG2 cells

Ocimum gratissimum is used as a traditional folk medicine in many countries. The objective of this study was to evaluate the antioxidant activities of an aqueous O. gratissimum extract (OGE) and to evaluate its cytoprotective activity against hydrogen peroxide-induced toxicity in human HepG2 cells. The results revealed that the total phenolic content of the OGE reached 20%. In the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the OGE reduced up to 80% of the free radicals at a plateau concentration of 66.7 μg/mL. This indicates that OGE contains considerable free radical scavenging activity. In a dose-dependent manner, OGE pretreatment counteracted the decrease in cell viability in H2O2-treated HepG2 cells (p < 0.05), and at a concentration of 20–80 μg/mL, it effectively reduced thiobarbituric acid reactive substance (TBARS) formation. These findings indicated that the aqueous extract of O. gratissimum has an antioxidant capacity and protective effect on oxidative stress in HepG2 cells. This makes OGE a promising therapeutic agent in liver diseases.