PHENOLICS CONTENT, ANTIOXIDANT, ANTIBACTERIAL AND ANTICANCER ACTIVITIES OF POMELO PEELS

Abstract

Pomelo peel, a byproduct of pomelo consumption, is high in nutrients and useful components such as phenols and flavonoids, yet the majority of it is discarded as waste materials. There is very few studies focus on the phytochemical compounds of pomelo peels, so, the current study investigated the antioxidant, antimicrobial, and anticancer activities of pomelo peels methanolic extract. The results showed that methanol produced the highest phenolics extraction yield (21.48%) and total polyphenols (798.17 mg GAE/g) from pomelo peels powder. HPLC analysis identified 15 phenolic compounds, with salicylic, ellagic, and catechin being the highest (2.19, 1.97 and 1.81 g/kg, respectively). The extract contained seven flavonoid components, with rosmarinic (1219.38mg/100g), hesperidin (424.08 mg/100g) and quercetrin (29.45 mg/100g) being the highest. The methanolic extract had a high antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) but lower than BHT as a standard synthetic antioxidant. The induction period (using the Rancimat instrument) was increased from 8.46 hr for virgin sunflower oil to 10.27 and 12.34 hr for sunflower oil containing 200 and 400 ppm of pomelo peels methanolic extract, respectively, compared with 13.58 hr for sunflower oil containing 200 ppm of BHT. The extract showed significant antimicrobial activity against Gram-positive bacteria and higher activity against HCT116 (human colon cancer) than HEPG2 (human liver cancer). So, pomelo peels could be used as a source of bioactive compounds in functional foods.