Antioxidant Potential of Extracts of Caja-Umbu Peels

This study was carried out to evaluate the antioxidant potential of the peel flour of caja-umbu fruits. Extracts were obtained using three systems: a) sequential extraction (acetone 80%, methanol 80% and water); b) sequential extraction (water, methanol 80% and acetone 80%); c) non-sequential extraction. The extracts were submitted to the determination of total phenolic and the antioxidant assay: DPPH• and ABTS•+ radical scavenging capacity and β- carotene/linoleic acid co-oxidation system. The sequential process that used 80% acetone as the first solvent was the most efficient in the extraction of polyphenols. The ability of hydroacetonic and hydromethanolic extracts to scavenge the DPPH radical after 15 mins of reaction was 94.7, 91.6 and 21.8% for the hydroacetonic, hydromethanolic and aqueous extracts of caja-umbu peel flour, respectively. The amounts of phenolics in the hydroacetonic and hydromethanolic extracts that were required to decrease the initial concentration of DPPH by half (EC50) were 0.26 and 0.35 g per g of DPPH. The times needed to decrease the initial concentration of DPPH by half (TEC50) were 2.45 and 2.87 min for the hydroacetonic and hydromethanolic extracts, respectively. The ability to scavenge the ABTS radical was 2557 and 2553 μmol Trolox equivalents of antioxidant activity per gram (TEAC/g), respectively for hydroacetonic and hydromethanolic extracts. The antioxidant activities of extracts on the β-carotene/linoleic acid co-oxidation system were 96.6 and 78.5% for hydroacetonic and hydromethanolic extracts, respectively. They inhibited oxidation by 96.64 and 78.45%, respectively. Caja-umbu peels exhibited good antioxidant capacities in different systems and thus may serve as potential source of natural antioxidant.