Organic acid, phenolic content and antioxidant activity of wild yam (Dioscorea spp.) tubers of Nepal

Four wild yam (Dioscorea spp.) tubers available in Nepal were analyzed for their individual organic acids, total phenolic contents and antioxidant activities. Succinic acid was predominant with an average value of 1316 mg/100 g fresh weight (FW). Citric acid was the second most abundant, with an average value of 274 mg/100 g FW. Average values recorded for malic and oxalic acids were 147 and 110 mg/100 g FW, respectively. Total polyphenol content (as phenol) ranged from 13 to 166 mg/100 g FW. Wild yam tubers were found to have significant antioxidant activities, as evaluated by different methods such as DPPH free radical scavenging, ferrous ion chelating, reducing power and total antioxidant activity tests. Consumption of fresh yam tubers may thus serve as a good source of antioxidant in its natural form; and may have role in prevention of human diseases, in which free radicals are involved, such as cancer and cardiovascular diseases.