Antioxidant activity of ethanolic extracts of purple and orange sweet potatoes (Ipomoea batatas L.)

Purple and orange sweet potatoes are rich in anthocyanin, beta-carotene and phenolic compounds, an important group of secondary metabolite compounds responsible for the antioxidant activity in fruits and vegetables. This work investigated the potential of ethanol extracts of purple sweet potato (EU) and orange sweet potato (EO) in scavenging free radical species using DPPH and FRAP methods and its correlation to total phenolic and flavonoid contents. The study results showed that EU has potent antioxidant activity with an IC50 value of 30.9 μg/mL. In comparison, EO has moderate antioxidant activity with an IC50 of 61.5 μg/mL in the DPPH assay. The ability of EU and EO to reduce free radical species using FRAP assay were 215.7 and 177.7 μmol TE/g extract, respectively. Besides that, the flavonoid contents of EU and EO were 34.0 and 22.8 mg QE/g extract, while its phenolic content was 5.97 g and 2.00 g GAE/100 g extract, respectively. These results indicated that ethanolic extracts from purple and orange sweet potatoes have a high potential to be used as a food supplement to protect the human body from diseases caused by free radical species.