Investigation of antioxidant activity and pancreatic lipase inhibitory potential of Ipomoea batatas L. extracts

Abstract

This study evaluated the antioxidant activity and pancreatic lipase inhibitory potential of ethanol extracts from three parts (stem, leaf, and sprout) of sweet potato (Ipomoea batatas L.). The ethanol extracts were quantified for total polyphenol content (TPC) and total flavonoid content (TFC), and their antioxidant activities were assessed using DPPH, ABTS, and ferric reducing antioxidant power (FRAP) assays. Pancreatic lipase inhibitory activity was determined in vitro using p-nitrophenyl laurate as a substrate, and further validated in vivo in Mus musculus mice through a lipid absorption test. The leaf extract demonstrated superior results compared to the stem and sprout extracts in terms of both compound content and antioxidant activity (TPC: 279.4 ± 1.83 mg GAE/g; TFC: 85.7 ± 1.21 mg QE/g; IC₅₀ ABTS: 47.33 ± 0.72 µg/mL; IC₅₀ DPPH: 80.86 ± 3.13 µg/mL). Notably, the leaf extract also exhibited the strongest pancreatic lipase inhibitory activity (IC₅₀ = 134.68 ± 1.27 µg/mL), being only approximately 2.3 times less potent than the positive control, orlistat. In vivo experiments confirmed that the leaf extract significantly reduced plasma triglyceride levels in mice after lipid emulsion administration, comparable to the effect of orlistat. These findings indicate that sweet potato leaves are a potential plant source rich in polyphenol and flavonoid compounds with considerable antioxidant and lipid-digesting enzyme inhibitory activities, providing a scientific basis for the development of formulations to aid in the management of obesity and lipid metabolism disorders.