Potential Antioxidative Activity of Waste Product of Purple Sweet Potato ( Lam.).

<b>Background and Objective:</b> Antioxidants are substances that can deactivate free radicals. Phenol and flavonoid are antioxidant compounds widely found in plants, including purple sweet potato (<i>Ipomoea batatas</i> L.). This research aimed to investigate three purple sweet potato-based organs' antioxidative activity and flavonoid contents. <b>Materials and Methods:</b> Antioxidative activities, total phenolic content and total flavonoid content were performed by UV-visible spectrophotometry. Pearson's method analyzed the correlation of TPC and TFC with antioxidative activities and the correlation between two antioxidative testing methods. <b>Results:</b> Antioxidative activity of three organs purple sweet potato using DPPH method showed values varied from 6.572-290.894 mg AAE g¹ and using CUPRAC method varied from 25.169-621.254 mg AAE g¹. The highest TPC was found in ethanolic leaves extract (20.885 g GAE 100 g¹), while the highest TFC was found in ethyl acetate leaves extract (10.048 g QE 100 g¹). <b>Conclusion:</b> DPPH and CUPRAC tests revealed that purple sweet potato leaves, stem and tuber extracts were potent antioxidants. The potential antioxidative activity was found in the waste product of purple sweet potatoes (leaves and stem). Phenol and flavonoid compounds had contributors to antioxidative activity. DPPH and CUPRAC methods gave linear results for most of the antioxidative activity in three organs of purple sweet potato. Ethanol stem extract contained luteolin 7-O-glucoside, rutin, quercetin, kaempferol and apigenin. Rutin had the highest content, which was 0.399%.