| Project/Area Number |
08680621
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bioorganic chemistry
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
KAWABATA Jun Hokkaido Univ., Fac.of Agric., Assoc.Prof., 農学部, 助教授 (60142197)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1996: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | burdock / chrysanthemum / caffeoylquinic acid / antioxidant / 抗酸化物性 / キク科野菜 / ポリフェノール / 抗酸化性 / リポソーム |
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| Research Abstract |
The Asteraceous vegetables, roots of burdock and leaves of garland chrysanthemum are commonly consumed in Japan. They contain a series of caffeoylquinic acids (CQAs) as the antioxidative principles. The antioxidative activity of the CQAs was determined by both TBA and thiocyanate methods using a liposome solution prepared by ultrasonication of egg lecithin or red blood cell ghosts prepared from horse blood. The inhibitory activity against the radical initiator-induced peroxidation of the liposome is in the order of DL-alpha-tocopherol (Toc) >tricaffeoylquinic acid (TCQA) >dicaffeoylquinic acids (DCQAs) >caffeic acid (CA) >chlorogenic acid (=monocaffeoylquinic acid, MCQA) , whereas that of the red blood cell ghosts is TCQA>DCQAs>CA>MCQA>Toc. These results indicate that the antioxidative activity of CQAs increases in proportion to the number of CA residues in the molecule. It should be reasonable to suppose that an ortho-diphenol structure of the CA residue is responsible for the activity. In order to obtain more detailed relationships between the antioxidative activity and the molecular structure, a radical quenching ability of the CQAs was next determined by a DPPH method. One molar of CA and MCQA quenched three DPPH radicals, which was one and half times more efficient than Toc. As expected, activity of DCQA and TCQA developed again in proportion to the number of CA residues. In the DCQA congeners, stronger activity was shown in the molecules carrying two CA residues close together. Moreover, the presence of additional acyl substituents such as succinate ester enhanced the activity. The neighboring effect of CA residues is interpreted by the assumption that the intramolecular coupling of CA radicals would regenerate an active phenolic group.
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