Chemical Characterization and Antioxidant Properties of Ethanolic Extract and Its Fractions from Sweet Potato (Ipomoea batatas L.) Leaves.

Chengcheng Zhang,Jianming Zhang,Xiaoqiong Li,Liehong Wu,Daqun Liu,Weicheng Wu

doi:10.3390/foods9010015

Chengcheng Zhang, Jianming Zhang + Show 4 more

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https://doi.org/10.3390/foods9010015

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Abstract

Sweet potato (Ipomoea batatas L.) leaf is a natural source of phenolic compounds with strong antioxidant activity and potential utility as an antioxidant. The aim of this study was to evaluate the polyphenol composition and antioxidant activities of ethanol extracts and their various solvent-partitioned fractions (petroleum ether, ethyl acetate, and aqueous fraction) from sweet potato leaves and petioles. Seven caffeoylquinic acid (CQA) derivatives and four flavonoids were detected in sweet potato leaves by HPLC-ESI-MS. The total phenolic content (TPC) and total flavonoid content (TFC) in leaf (112.98 ± 4.14 mg gallic acid equivalent (GAE)/g of dried extract, 56.87 ± 5.69 mg rutin equivalent (RE)/g of dried extract) was more than ten times higher than in petiole (9.22 ± 2.67 mg GAE/g of dried extract, 3.81 ± 0.52 mg RE/g of dried extract). The antioxidant contents of ethyl acetate fractions increased dramatically relative to those of crude extracts for both leaves and petioles. Purification using solvent partition with ethyl acetate increased TPC and TFC of crude extracts, especially the CQA derivatives including 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, and 3,4,5-tricaffeoylquinic acid. Meanwhile, the ethyl acetate fractions with the highest CQA content were associated with the highest scavenging activities towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) and higher ferric ion reducing antioxidant power (FRAP)-reducing power.

Highlights

Sweet potato (Ipomoea batatas L.) is a food crop from the morning glory family of Convolvulaceae.It is widely consumed around the world [1]
The results showed that purified extract, the ethyl acetate fraction, revealed the highest total phenolic and total flavonoid contents, and showed the strongest antioxidant activity compared to crude extract
23.9 mg/g in leafpetiole petroleum etherether extract (LPE) and petiole petroleum extract (PPE), respectively) and ethyl acetate fractions (12.5 and 6.3 mg/g in leaf acetate extract (LEE) and petiole acetateacetate extractextract (PEE), respectively). These results suggest that sweet potato leaves may possess a number of water-soluble components such as proteins, minerals, and carbohydrates [2]

Summary

Introduction

Sweet potato (Ipomoea batatas L.) is a food crop from the morning glory family of Convolvulaceae. It is widely consumed around the world [1]. The sweet potato leaves are rich in polyphenols, proteins, vitamins, minerals, and other functional microcomponents [2,3]. Especially di-CQA and 3,4,5-triCQA, have strong antioxidant capacities: Free radical scavenging, metal chelation, and inhibition of lipid peroxidation [8,9,10]. Liu et al [11] studied the antioxidant activity of Jishu No 18 sweet potato leaves cultivar and demonstrated that its ferric ion reducing

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