Title: Nutritional and phytochemical profile of pomegranate (Wonderful variety) peel and its effects on hepatic oxidative stress and metabolic alterations
Pomegranate is a healthy fruit. The peel contains antioxidant phytochemicals that may potentiate health benefits but remains under-explored. We evaluated the antioxidant, nutritional and phytochemical profiles of the peel of the “Wonderful” variety pomegranate and its influence on oxidative and metabolic alterations in hepatic tissues. The peel contained appreciable amounts of some beneficial trace minerals and both essential and non-essential amino acids. Mostly Omega 3 and 6 fatty acids were found. The peel extracts exhibited in vitro radical scavenging and Fe3+ reducing antioxidant activities and dose-dependently prevented oxidative stress-induced lipid peroxidation and GSH depletion in both Chang liver cells (IC50 = 18.0 ± 1.46 and 11.2 ± 0.99 µg/ mL, respectively) and isolated rat liver tissues (IC50 = 96.7 ± 3.34 and 19.4 ± 3.36 µg/mL, respectively). The antioxidant effects were comparable to that of ascorbic and correlated with their phenolic profile. HPLC analysis identified antioxidant phenolic acids (gallic acid, syringic acid ferulic acid p-coumaric acid, etc.). The peel did not cause notable cytotoxicity in liver and kidney cells, which suggests minimal safety concerns. Metabolomics analysis revealed alterations in hepatic fatty acid, amino acid, and nucleic acid metabolisms following the induction of oxidative stress. These alterations were improved in the acetone extract-treated hepatic tissues, with concomitant activation of vitamin and selonocompound metabolisms. The data suggest that the fruit peel of “Wonderful” variety pomegranate may be an underutilized source of functional nutrients and antioxidants phenolic acids for optimum body function and mitigation of hepatic oxidative damage and associated metabolic alterations.