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KMID : 0043320070300020146
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Archives of Pharmacal Research
2007 Volume.30 No. 2 p.146 ~ p.150
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Flavonoids from the Flower of Rhododendron yedoense var. Poukhanense and Their Antioxidant Activities
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Jung Sung-Je
Kim Dong-Hyun
Hong Yoon-Hee
Lee Jin-Hee
Song Hyo-Nam
Rho Young-Deok
Baek Nam-In
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Abstract
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Antioxidant flavonoids have been isolated from the flower of Rhododendron yedoense var. poukhanense. One new flavonoid and three known flavonoids, quercetin-5-O-β-D-glucopyranoside (1), quercetin (3), and quercitrin (4), were isolated from the butanol and ethyl acetate extracts of the plant. The new flavonoid was identified as myricitrin-5-methyl ether (2). The isolation of these flavonoids from this plant, for the first time, is a valuable finding. The flavonoids were evaluated for their antioxidant activities using 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH), TBARS (thiobarbituric acid reactive substance) and superoxide anion radical (O2?) in the xanthine/xanthine oxidase assay system. In the DPPH scavenging assay, the IC50 values were 4.5±0.48 μM for compound 2 and 9.7±0.29 μM for compound 3, which showed an antioxidant activity approximately 1.5~2 times higher than the antioxidant activity of α-tocopherol (9.8±0.94μM). Additionally, the antioxidant activities of myricitrin-5-methyl ether (2) (IC50 = 1.7±0.22 μM) and quercetrin (4) (IC50 = 1.9±0.63 μM) were higher than that of L-ascorbic acid (IC50 = 7.4±0.63μM) when evaluated using a TBARS assay. Compound 2 showed high activity in both the inhibition of xanthine oxidase (1.1±0.21 mM) and in the activation of superoxide scavenging.
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KEYWORD
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Rhododendron yedoense, Ericaceae, Antioxidant activity, DPPH scavenging assay, TBARS assay, Xanthine oxidase inhibition assay, Superoxide anion radical scavenging assay, Myricitrin-5-methyl ether
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