Polyphenolic content and their antioxidant activity in leaf extract of sweet potato (Ipomoea batatas )

Nowadays, phytochemicals and antioxidants in plants are raising interest in consumers for their roles in the maintenance of human health. Phenolics and flavonoids are known for their health-promoting properties due to protective effects against cardiovascular disease, cancers and other disease. In this study, total phenolic (TP), total flavonoids (TF) and antioxidant activities of the six different varieties of sweet potato (Ipomoea batatas) leaf extracts were determined. TP content varied from 4.47±1.88 to 8.11±2.11 mg/g DW in the leaf extracts and high content of TP was observed in Vardaman variety. TF content in the extracts ranged from 1.87±0.84 and 3.95±0.91 mg/g DW and Bush Porto Rico variety showed highest content. The antioxidant activity determined by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) and ferric reduction antioxidant power (FRAP) showed high activities (IC50 value of 184.3 μg/mL) in the leaves of Vardaman variety while the Centennial variety showed the lowest activity (IC50=450.46 μg/mL). Antioxidant activity was highly correlated with TP content (R 2 =0.827, P<0.001) while, no significant correlation was observed between TF content and antioxidant activity (R 2 =0.0448). Therefore, the total phenolic content could be served as a useful indicator for the antioxidant activities of sweet potatoes. This study validated the medicinal potential of the sweet potatoes leaf.