Antioxidant Activity of Isoquercitrin and Caffeoylquinic Acid Derivatives from Sweet Potato Stems and Leaves
LI Jia-yin1,2,YU Huan2,SHI Bo-yang1,2,LI Mi-lu2,LU Ying1,2,*
2013, 34(7):
111-114.
doi:10.7506/spkx1002-6630-201307023
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The antioxidant activity of four major polyphenolic compounds, namely quercetin-3-O-β-D-glucoside (Q-Glu),
4,5-di-O-caffeoylquinic acid (4,5-diCQA), 3,4-di-O-caffeoylquinic acid (3,4-diCQA) and 3,5-di-O-caffeoylquinic acid
(3,5-diCQA) derived from sweet potato stems and leaves were evaluated based on reducing power, DPPH, hydroxyl and
superoxide anion free radical scavenging, and anti-lipidperoxidation assays and compared with that of VC. These four
polyphenolic compounds demonstrated strong antioxidant activity in a concentration-dependent manner. The IC50 values of
Q-Glu, 3,5-diCQA, 3,4-diCQA, 4,5-diCQA against DPPH and hydroxyl free radicals were 47.27, 41.61, 43.55, 46.02 μmol/L, and
190.99, 151.20, 151.24, 217.31 μmol/L, respectively, whereas the IC50 values of Q-Glu3, 5-diCQA, and 3, 4-diCQA against
superoxide anion free radical were 0.81, 0.46, 0.71 mmol/L, respectively. In anti-lipidperoxidation assay the IC50 values
of 3,5-diCQA, 3,4-diCQA, and 4,5-diCQA were 4.44, 2.53, 3.13 mmol/L, respectively. Within the studied concentration
range, however, 4,5-diCQA and Q-Glu did not reach 50% superoxide anion free radical scavenging and lipidperoxidation.
Among these compounds, 3,5-diCQA showed the strongest reducing power and radical scavenging activity, and the antilipidperoxidation
activity of 3,4-diCQA was the highest. These results show that these four polyphenolic compounds from
sweet potatoes stems and leaves have significant antioxidant effects and are promising natural antioxidants.