Ginger extract modulates Pb-induced hepatic oxidative stress and expression of antioxidant gene transcripts in rat liver.

CONTEXT: Spices and herbs are recognized sources of natural antioxidants that can protect from oxidative stress, thus play an important role in chemoprevention of liver diseases. Ginger is used worldwide primarily as a spicy condiment.
OBJECTIVE: This study evaluated the ability of ginger extract (GE) to ameliorate oxidative-hepatic toxicity induced by lead acetate (PbAc) in rats.
MATERIALS AND METHODS: Five groups of animals were used: group I kept as control; groups II, IV, and V received PbAc (1 ppm in drinking water daily for 6 weeks, and kept for an additional 2 weeks without PbAc exposure); group III treated orally with GE (350 mg/kg body weight, 4 d per week) for 6 weeks; group IV (protective) received GE for 2 weeks before and simultaneously with PbAc; and group V (treatment) received GE for 2 weeks after PbAc exposure.
RESULTS: GC-MS analysis of GE revealed its content of gingerol (7.09%), quercetin (3.20%), dl-limonene (0.96%), and zingiberene (0.18%). Treatment of PbAc-treated rats with GE has no effect on hepatic Pb concentrations. However, it maintained serum aspartate aminotransferase level, increased hepatic glutathione (157%), glutathione S-transferase (GST) (228%), glutathione peroxidase (GPx) (138%) and catalase (CAT) (112%) levels, and reduced hepatic malondialdehyde (80%). Co-treatment of PbAc group with GE upregulated mRNA expression of antioxidant genes: GST-α1 (1.4-fold), GPx1 (1.8-fold), and CAT (8-fold), while post-treatment with GE upregulated only mRNA expression of GPx1 (1.5-fold).
CONCLUSION: GE has an antioxidant protective efficacy against PbAc-induced hepatotoxicity, which appears more effective than its therapeutic application. However, the changes in antioxidant gene expression were not reflected at the protein level.