In the bioethanol production process employing citrus peels, a large amount of enzymatic hydrolyzed residues is generated as waste material. The bioactive compounds, and antioxidant and anticancer activities of these residues were investigated in the present study. Hydrolyzed citrus residues exhibited similar antioxidant activity as the unhydrolyzed control, which was positively correlated to the contents of total phenols, flavonoids and total carotenoid. Some flavonoids (naringin, naringenin, hesperetin and neohesperidin) and two high value co-products (D-limonene and galacturonic acid) were detected only in hydrolyzed residues. In addition, hydrolyzed residues showed antiproliferative activity and sub-Gl arrest in human melanoma A375 and colon cancer HCT116 cells. These results provide an alternative use for hydrolyzed citrus residues in the functional food, cosmetic and pharmaceutical industries.
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