The Antioxidant Potency of Punica granatum L. Fruit Peel Reduces Cell Proliferation and Induces Apoptosis on Breast Cancer

Pomegranate (Punica granatum L.) is known to possess pharmacological activities, such as antioxidant and anticancer. In this study, we evaluated the antioxidant potency of a methanolic pomegranate fruit peel extract (PPE) and the relation with its antiproliferative and apoptotic effects on MCF-7 human breast cancer cells. Total phenolic content and antioxidant activity of PPE were determined using the Folin-Ciocalteau and the 2,2-diphenyl-l-picrylhydrazyl free radical methods, respectively. Phenolic acids present in the extract were characterized by a reverse-phase high-performance liquid chromatography (HPLC) method. Cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. The apoptotic effects were determined by in situ Tdt-mediated dUTP nick end-labeling assay, and Bax/Bcl-2 mRNA expression levels were measured by reverse transcription-polymerase chain reaction. The extraction yield as a percentage of plant material was 37.97% (wt/wt), and total phenolic content was 331.28 mg of gallic acid equivalents/g of extract. According to HPLC analysis, the most abundant phenolic acid detected in the extract was ellagic acid. MCF-7 cell proliferation decreased depending on PPE concentration (25, 50, 100, 200, and 300 mu g/mL) and incubation times (24, 48, and 72 hours). After 48 and 72 hours, the apoptotic cell numbers were significantly increased at 100, 200, and 300 mu g/mL PPE concentrations. In addition, expression of the pro-apoptotic gene Bax was increased, and that of the anti-apoptotic gene Bcl-2 was decreased after 200 and 300 mu g/mL PPE treatment for 48 and 72 hours. Because PPE reduced cell proliferation and induced apoptosis on MCF-7 cancer cells, we believe that PPE has important antioxidant and apoptotic effects.