Analysis of antioxidant activity and antioxidant constituents of Chinese toon |
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Authors: | Ka-Wing Cheng Ray-Yu Yang Samson CS Tsou Clive SC Lo Chi-Tang Ho Tung-Ching Lee Mingfu Wang |
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Affiliation: | 1. School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, PR China;2. Asian Vegetable Research and Development Center, Tainan, Taiwan;3. Department of Food Science and the Center for Advanced Food Technology, Rutgers University, 65 Dudley Road, New Brunswick, NJ 08901-8520, USA |
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Abstract: | Antioxidant activity of the methanol and water extracts of Chinese toon (Toona sinensis) leaf was evaluated using DPPH radical scavenging and lipid peroxidation assays. Contents of four major types of antioxidants including β-carotene, ascorbate, α-tocopherol and phenolics were also quantified. Open column chromatography followed by semi-preparative HPLC were applied to separate phenolic antioxidants whose contents were subsequently determined by HPLC. The methanol extract demonstrated much higher antioxidant activity than the water extract. Contents of β-carotene, ascorbate, α-tocopherol and phenolics were 1.23 μmol g?1, 34.2 μmol g?1, 2.40 μmol g?1 and 872 μmol gallic acid equivalents g?1, respectively. Six phenols were isolated. Their structures were characterized as 5-O-galloylquinic acid, gallic acid, methyl gallate, β-1,2,6-tri-O-galloyl-d-glucose, quercetin 3-O-β-d-glucopyranoside and quercetin 3-O-(2′′-O-galloyl)-β-d-glucopyranoside, respectively. The results indicate that phenolic compounds are the dominant antioxidants in Chinese toon. The compounds β-1,2,6-tri-O-galloyl-d-glucose and quercetin 3-O-(2′′-O-galloyl)-β-d-glucopyranoside were reported for the first time in Chinese toon. |
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