Abstract:

Antioxidant capacity is an important factor indicating nutritional and health value of fruits and vegetables. Yacon is a both edible and medicinal plant, which has some preventing roles for a number of chronic diseases. In this study, to assess the in vitro antioxidant potential of yacon tubers, the 60% methanol extract from yacon tubers was tested for its scavenging capacities against DPPH, ABTS+·, superoxide anion radicals, ferric reducing antioxidant power and ferrous ions chelating capacity. The DPPH radical scavenging assay of the extract showed a trolox equivalent antioxidant capacity (TEAC) of 410.263mg Trolox /g md, a ascorbic acid equivalent antioxidant capacity (AEAC) of 230.485 mg VC/g md and a median inhibition concentration (IC50) of 1.464 mg/mL, and the ABTS+· radical scavenging assay showed a TEAC of 267.584 mg Trolox/g md, an AEAC of 41.597 mg VC/g md and an IC50 of 1.269 mg/mL, and the TEAC, AEAC and IC50 obtained in the superoxide anion radical assay were 652.816 mg Trolox/g md, 101.451 mg VC/g md and 7.720 mg/mL, respectively. These results demonstrate that the extract from yacon tubers has scavenging effect against all DPPH, ABTS+·, superoxide anion radicals. Moreover, the extract also presented high ferric reducing antioxidant power (131.723 mg FeSO4 /g md) and strong ferrous ions chelating capacity (73.193%).

Key words: yacon, tuber, antioxidant activity, radical