水溶液中におけるテトラヒドロクルクミンの酸化安定性と酸解離特性の評価  [in Japanese] Evaluation of Stability Against Oxidation and Acid Dissociation Properties for Tetrahydrocurcumin in Aqueous Solution  [in Japanese]

Author(s)

Abstract

クルクミンの還元体であるテトラヒドロクルクミンはクルクミンに比べ抗酸化活性が高いと言われている.本研究ではその抗酸化活性解明を目的とし水溶液中における安定性と酸解離特性を初めて明らかにし,クルクミンと比較検討した.クルクミンはpH 3.0~10.0の水溶液中で空気酸化を受け1時間以内に分解した.特にpH 8.0では速やかに分解した(半減期1.0 min).一方テトラヒドロクルクミンは2時間の間分解せず,空気酸化に対する高い安定性が示された.吸光光度滴定によりテトラヒドロクルクミンの酸解離定数を算出したところp<i>K</i><sub>a1</sub> = 8.59 ± 0.06,p<i>K</i><sub>a2</sub> = 9.53 ± 0.01,p<i>K</i><sub>a3</sub> = 10.74 ± 0.02となり,比較のため求めたクルクミシの酸解離定数(p<i>K</i><sub>a1</sub> = 8.47 ± 0.032,p<i>K</i><sub>a2</sub> = 9.43 ± 0.025,p<i>K</i><sub>a3</sub> = 10.59 ± 0.03)より各々0.1程度大きい値となった.

Tetrahydrocurcumin has been of interest, the antioxidative activity of which has been reported to be higher than that of curcumin. In an attempt to investigate the function, we studied the stability of tetrahydrocurcumin in aqueous solutions and the acid dissociation properties, and compared them with those of curcumin. In aqueous solutions of pH 3.0∼10.0 under air - saturated conditions, curcumin showed complete decomposition within l h. At pH 8.0, curcumin decomposed rapidly with a half-life time of 1.0 min. On the other hand, tetrahydrocurcumin did not show any detectable decomposition within 2 h, showing higher stability in aqueous solutions under air. The acid-dissociation constants of tetrahydrocurcumin were estimated to be p<i>K</i><sub>a1</sub> = 8.59 ± 0.06, p<i>K</i><sub>a2</sub> = 9.53 ± 0.01, p<i>K</i><sub>a3</sub> = 10.74 ± 0.02, which are slightly larger than those of curcumin (p<i>K</i><sub>a1</sub> = 8.47 ± 0.032, p<i>K</i><sub>a2</sub> = 9.43 ± 0.025, p<i>K</i><sub>a3</sub> = 10.59 ± 0.03) by 0.1 p<i>K</i><sub>a</sub> unit.

Journal

  • BUNSEKI KAGAKU

    BUNSEKI KAGAKU 57(4), 257-263, 2008-04-05

    The Japan Society for Analytical Chemistry

References:  18

Codes

  • NII Article ID (NAID)
    110006656121
  • NII NACSIS-CAT ID (NCID)
    AN00222633
  • Text Lang
    JPN
  • Article Type
    ART
  • ISSN
    05251931
  • NDL Article ID
    9465966
  • NDL Source Classification
    ZP4(科学技術--化学・化学工業--分析化学)
  • NDL Call No.
    Z17-9
  • Data Source
    CJP  NDL  NII-ELS  IR  J-STAGE  NDL-Digital 
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