| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2004: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2003: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
This study was aimed to determine the structures of allspice constituents and elucidate their antioxidant properties as well as the factors of antioxidant activity. Dried allspice was successively extracted with n-hexane, dichloromethane and 70% aqueous acetone at room temperature. After removing acetone from the 70% aqueous acetone extract, the resulting aqueous residue was separated into the dichloromethane-soluble, ethyl acetate-soluble and water-soluble fractions. The ethyl acetate-soluble fraction which showed a strong DPPH radical scavenging activity and a high inhibitory effect on the autoxidation of methyl linoleate in bulk system was purified using repeated chromatographic techniques to give twenty compounds including two phenylpropanoids, eleven flavonoids and seven gallic acid related compounds. Their structures were elucidated on the basis of some spectral data. Among them, five are new and fifteen are known. However ten known compounds were first isolated from allspice. Th
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e antioxidant properties of these isolated compounds together with seventeen compounds which have been already isolated in our laboratory were evaluated using several different methods. The DPPH radical scavenging activity was dependent on the number of ortho-diphenols. The O_2^- radical scavenging activity of compounds with 1,2,3-trihydroxyphenyl groups is stronger than that of compounds with 1,2-dihydroxyphenyl groups. Ortho-diphenol structure was contributed to the inhibitory effects on autoxidation of methyl linoleate in bulk system. When measured at 90℃, the high polar compounds such as tannin and flavonoid glycosides showed slight activity, which suggested that affinity to substrate oil might have some influence on their activity in bulk system at 90℃. Such phenomenon was not observed when measured at 40℃. Tannin showed very strong activity toward liposome oxidation induced by AAPH. In the case of flavonoid, quercetin related compounds showed stronger activity than myricetin related compounds. In addition, the inhibitory effects of six allspice constituents on the autoxidation of dressing at 20℃ were measured. The activity order was consistent with the scavenging activity order against DPPH and in this case the polarity of tested compounds did not influence the activity. In conclusion, compounds with ortho-diphenol structure contributed to the antioxidant effect of allspice, and their antioxidant properties might be governed by their radical scavenging abilities and polarities. Less
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