Publication:

Isolation and characterization of flavonoid fractions from orange peel with antioxidant properties

Background Citrus sinensis peel is an abundant agro-industrial byproduct rich in flavonoids and a potentially underexploited source of natural antioxidants. This study aimed to extract, characterize, and evaluate the antioxidant potential of flavonoid fractions from orange peel for food and pharmaceutical applications.

Methods Dried Citrus sinensis peel underwent hydroalcoholic extraction (ethanol: water, 1:1 v/v) for 72 hours by column chromatography purification. Characterization utilized HPLC, UV-Vis, and FTIR spectroscopy. Antioxidant activity was quantified via DPPH radical scavenging and FRAP assays.

Results HPLC identified hesperidin as the predominant flavonoid (52.4 mg/g extract), followed by naringin (18.9 mg/g), rutin (13.7 mg/g), and quercetin (8.5 mg/g). Total flavonoid content was 4.29 mg quercetin equivalents/g extract. The extract demonstrated concentration-dependent DPPH scavenging (32.4–88.6% at 0.5–2.5 mg/ml; IC₅₀=1.21 mg/ml) and strong ferric reducing capacity (1655±18 µmol Fe(II)/g). FTIR confirmed characteristic flavonoid functional groups.

Conclusions Citrus sinensis peel extract exhibits significant antioxidant activity, validating its potential as a sustainable natural antioxidant source for food preservation and pharmaceutical formulations.