Characterization of the radical-scavenging reaction of 2-0-substituted ascorbic acid derivatives, AA-2G, AA-2P, and AA-2S:: A kinetic and stoichiometric study
Characterization of the radical-scavenging reaction of 2-0-substituted ascorbic acid derivatives, AA-2G, AA-2P, and AA-2S:: A kinetic and stoichiometric study
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DOI：
10.1248/bpb.29.766
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发表时间：
2006-04-01
影响因子：
2
通讯作者：
Yamamoto, I
中科院分区：
文献类型：
--
作者：
Takebayashi, J;Tai, A;Yamamoto, I
研究了3种抗坏血酸（AA）2位O-取代衍生物：抗坏血酸2-葡萄糖苷（AA-2G）、抗坏血酸2-磷酸盐（AA-2 P）和抗坏血酸2-硫酸盐（AA-2S）的抗氧化活性。研究了这些AA衍生物与常见的低分子量抗氧化剂尿酸、谷胱甘肽对1，1-二苯基苦基肼（DPPH）自由基、2，2 ′-连氮双（3-乙基苯并噻唑啉-6-磺酸）阳离子自由基（ABTS（.+））、或galvinoxyl自由基进行动力学和化学计量评价。这些AA衍生物与DPPR自由基和ABTS（.+）缓慢而连续地反应，但不含galvinoxyl自由基。它们在酸性条件下能与DPPH自由基反应，在酸性条件下能与ABTS（.+）在中性条件下。相比之下，AA立即淬灭所有种类的自由基测试在所有pH值的调查。水溶性维生素E类似物Trolox的反应性在动力学和化学计量学方面与AA的反应性相当。尿酸和谷胱甘肽在一定的pH条件下对这些自由基表现出持久的自由基清除活性。AA衍生物的自由基清除概况更接近尿酸和谷胱甘肽，而不是AA的。在适当的条件下，由一个分子的AA衍生物，尿酸，或谷胱甘肽清除的自由基的数量等于或大于由AA或Trolox。这些数据表明AA衍生物作为自由基清除剂的潜在用途。
The aim of this study was to characterize the antioxidant activity of three ascorbic acid (AA) derivatives O-substituted at the C-2 position of AA: ascorbic acid 2-glucoside (AA-2G), ascorbic acid 2-phosphate (AA-2P), and ascorbic acid 2-sulfate (AA-2S). The radical-scavenging activities of these AA derivatives and some common low molecular-weight antioxidants such as uric acid or glutathione against 1,1-diphenyl-picrylhydrazyl (DPPH) radical, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(.+)), or galvinoxyl radical were kinetically and stoichiometrically evaluated under pH-controlled conditions. Those AA derivatives slowly and continuously reacted with DPPR radical and ABTS(.+), but not with galvinoxyl radical. They effectively reacted with DPPH radical under acidic conditions and with ABTS(.+) under neutral conditions. In contrast, AA immediately quenched all species of radicals tested at all pH values investigated. The reactivity of Trolox, a water-soluble vitamin E analogue, was comparable to that of AA in terms of kinetics and stoichiometrics. Uric acid and glutathione exhibited long-lasting radical-scavenging activity against these radicals under certain pH conditions. The radical-scavenging profiles of AA derivatives were closer to those of uric acid and glutathione rather than to that of AA. The number of radicals scavenged by one molecule of AA derivatives, uric acid, or glutathione was equal to or greater than that by AA or Trolox under the appropriate conditions. These data suggest the potential usage of AA derivatives as radical scavengers.