Antioxidant Activity of Flavonoid Compounds in Ethanol and Ethyl Acetate Extract from Citrus Sinensis

Citrus sinensis have potential resources of natural antioxidant content. This study aimed to identify the antioxidant potential, especially the flavonoid compounds in the extract of sweet orange peel (Citrus sinensis). The method of extraction was maceration in ethanol and ethyl acetate solvents. Willstatter, Bate-Smith, and FeCl3 tests were used to screen flavonoid compounds, and total flavonoid content was measured using an aluminum chloride colorimetric assay. Antioxidant activity was determined using the DPPH and H202 methods by taking the IC50 value. The total content of flavonoids was found higher in ethyl acetate extract ($242.48\ \pm 13.83\ \text{mg}$ QE/ gram DW) than in the ethanol extract. The most potent hydrogen peroxide inhibition activity and DPPH inhibition activity were found in the ethyl acetate extract through the value of IC50 511.63 µg/ml in DPPH and IC50 47.78 µg/ml in hydrogen peroxide. Therefore, ethyl acetate extract had the highest antioxidant potential and highest total flavonoid content.