Phytochemicals, Antioxidant Activity and Identification of Phenolic Compounds by HPLC of Pomegranate (Punica granatum L.) Peel Extracts

Abstract

Pomegranate peel is food waste unfit to eat parts obtained during the production of pomegranate juice. The aim of this work is to study the effect of four different solvents (ethanol, isopropanol, hot and cold water) on phytochemicals screening, total phenolics content, total flavonoid content and antioxidants activity in pomegranate peels, as well as identification of phenolic compounds in extracts by HPLC. Phenolics, flavonoids, alkaloids, saponins, tannins, steroids and terpenoids were detected in all extracts. The highest total phenolics and total flavonoids were observed in ethanol extract of pomegranate peels (161.5 mg GAE/g and 70.65 mg Rutin/g), respectively. Furthermore, the ethanol extract of pomegranate peels showed the highest DPPH scavenging activity with the lowest IC50 value 14.6 μg/ml compared to other extracts. The high antioxidant activities may be due to the high contents of phenolics and flavonoids in pomegranate peel ethanol extract. HPLC analysis was used for the identification and quantitative determination of phenolic compounds in pomegranate peels extracts. The results revealed nine polyphenolic compounds including protocatechuic acid, p-coumaric acid, caffeic acid, ellagic acid, cinnamic acid, quinic acid, benzoic acid, syringic acid and iso-ferulic acid in pomegranate peels extracts. The obtained results confirmed that ethanol extract was the most abundant of phenolics compounds as compared to the other extracts. Finally, it can be concluded that pomegranate peel extracts can be used in various fields for being rich in natural antioxidants that have a medicinal and therapeutic impact.