Antioxidant Capacities of Various Extracts from Purple Sweet Potatoes (Ipomoea batatas (L.) Lamk.) Tubers and Isolation of Antioxidant Compound

Irda Fidrianny, Komar Ruslan, Rosalina Diani

Abstract


Introduction: Purple sweet potatoes (Ipomoea batatas (L) Lamk.) tubers had been used as staple food because of its low glycemic index, high fiber, and minerals. Purple sweet potato tuber contains compounds which have antioxidant, anticancer and antibacterial activities. Objective: The aim of this research were to determine antioxidant capacities of various extracts of purple sweet potatoes (Ipomoea batatas) tubers by using DPPH method, its correlation with total flavonoid, phenolic, tannin content and isolation of antioxidant compound.

Method: Crude drug was extracted by reflux using solvent with increasing polarity, n-hexane, ethyl acetate, and ethanol. Antioxidant activity of each extract was measured by 2,2-diphenyl-1-picrilhydrazyl (DPPH) scavenging method. Total flavonoids, total phenols Ethyl acetate extract was fractionated by vacuum liquid chromatography. Purification was done by preparative thin layer chromatography (TLC). Pure compound was characterized by specific spray reagent, UV-vis spectrophotometry, two dimensional paper chromatography and infrared spectrophotometry.

Results: Crude drug of purple sweet potatoes tubers contain flavonoids, phenolic, tannins and steroid/triterpenoid. The highest DPPH scavenging activity (49.69 %) was given by ethyl acetate extract (with density of extract was 1.36 g/mL). Ethanol extract had the highest total phenolic (2.45 g GAE/100 g) and the highest total flavonoid. (0.97 g QE/100 g)was given by ethyl acetate extract. Antioxidant activities of purple sweet potatoes tubers extracts had significantly correlation with total phenolic and total flavonoid. An antioxidant compound J which was isolated from ethyl acetate extract was flavonoid compound.

Conclusion: Phenolic and flavonoid compounds were the major contributors in antioxidant capacities of purple sweet potatoes tubers. Antioxidant compound R was supposed to be flavonol aglycone that has OH at C-5 and substituted OH at C-3.


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