Citrus reticulata Blanco peels as a source of antioxidant and anti-proliferative phenolic compounds

Citrus reticulata Blanco industrial use worldwide generates millions of tons of by-products, mainly peels, with negative environmental impact. The main purpose of this work was to compare the extraction efficiency of water and 70% ethanol, for recovering C. reticulata peel phenolic compounds. A simple solid phase extraction method was used for obtaining enriched phenolic extracts. There were no significant differences in the extraction efficiency for the two solvents used. The main components were hesperidin, naringin, tangeritin, and rutin, that accounted for nearly 86% of the total phenolics extracted. Solid phase extraction allowed a 4.5-fold enrichment in phenolics and antioxidant activity of the extracts. The anti-proliferative activity of the extracts was found to be dose-dependent but also dependent on the cell line. The solid phase extraction enriched phenolic extracts after 48 h exposure presented an IC50 of 174.5 +/- 5.8 mu g/mL (BT-474), 391.9 +/- 15 mu g/mL (Caco-2) and > 500.00 mu g/mL (HepG2). These results show that C. reticulata peels are a cheap and abundant source of antioxidant and potentially bioactive phenolic compounds.