Phenolic content and antioxidant activity of ethanolic extracts from Citrus sinensis L. and Citrus reticulata L. fruits

Abstract

Citrus fruits, in particular the genus Citrus, are very rich in antioxidants which have beneficial effects on human health. The objective of this study was to evaluate the phenolic content and the antioxidant activity of the ethanolic extracts from orange (Citrus sinensis L.) and mandarin (Citrus reticulata L.) fruits. The quantitative estimation of the total phenolic content in the two extracts revealed their richness in these compounds. The results obtained showed that the polyphenols content were 159.66 ± 2.62 mg GAE / g of dry extract and 127.33 ± 2.32 mg GAE / g of dry extract for C. sinensis and C. reticulata, respectively.The quantification of flavonoids content showed that the ethanolic extracts of C. sinensis and C. reticulata contained 0.85 ± 0.01 mg QE / g of dry extract and 0.876 ± 0.073 mg QE / g of dry extract, respectively. Whereas, the tannins contents were 46.32 ± 1.02 mg TAE / g of dry extract for  C. sinensis and 47.65 ± 1.36 mg TAE / g of dry extract for C. reticulata. In vitro antioxidant activity was evaluated using two tests: the reducing power and the hydroxyl radical scavenger test. The evaluation of the two extracts by the ferric iron reducing power test showed an EC50 value of 0.882 ± 0.037 mg / ml for  C. sinensis extract and an EC50 of 1.085 ± 0.068 mg / ml for C. reticulata extract. In addition, C. sinensis and C. reticulata showed good hydroxyl radical scavenging effect with IC50 values of 0.303 ± 0.026 mg /ml and 0.572 ± 0.100 mg / ml for C. sinensis and C. reticulata, respectively. These results suggested that these fruit extracts could be good sources of phenolic compounds and ingredients with high antioxidant potential. Keywords: Citrus sinensis, Citrus reticulata, Polyphenols, Flavonoids, Tannins, Antioxidant activity.