Pomegranate (Punica granatum) peel extract provides protection against mercuric chloride-induced oxidative stress in Wistar strain rats

Context: Pomegranate [Punica granatum L. (Lythraceae)] is rich in antioxidants. Objective: The present work was undertaken to evaluate the protective effects of methanol extract of pomegranate peel extract (PPE) against a rat model of oxidative stress generated by treatment with mercuric chloride (HgCl2). Materials and methods: Rats were injected with HgCl2 (5 mg/kg body weight in 0.9% NaCl) for developing oxidative stress. The methanol extract of pomegranate peel (PPE) was suspended in 0.5% sodium carboxymethylcellulose and fed to rats at 50 mg/kg body weight/day up to 30 days after HgCl2 treatment. Biomarkers of oxidative stress including erythrocyte plasma membrane redox system (PMRS), lipid peroxidation, advanced oxidation protein products (AOPP), intracellular glutathione, and plasma antioxidant capacity as FRAP values were measured after PPE supplementation. Results: HgCl2-treated rats showed increased oxidative stress as evidenced by increased activity of erythrocyte PMRS 153%, lipid peroxidation 31%, and AOPP 290%. There was a significant (p < 0.01) decrease (25%) in plasma antioxidant capacity and intracellular glutathione (75%). Supplementation with PPE protected rats from HgCl2 induced oxidative damage. PPE supplementation to control rats increased antioxidant defense. Discussion and conclusion: The results clearly demonstrate that PPE treatment augments the antioxidant defense mechanism in mercuric chloride-induced oxidant toxicity. To the best of our knowledge this is the first report of the increase in erythrocyte PMRS activity in rats after supplementation with any kind of antioxidant supplementation. This study emphasizes the need for characterizing PPE for potential unknown antioxidant compounds.