morin radical

• 分子结构分类: 有机化合物 - 苯丙烷和聚酮 - 黄酮类化合物
• 英文名称: morin radical
• 化学式: C₁₅H₉O₇
• 分子量: 301.232
• InChiKey: PNYQWMSGGIEMRZ-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  2.43
• 重原子数：
  22.0
• 可旋转键数：
  1.0
• 环数：
  3.0
• sp3杂化的碳原子比例：
  0.0
• 拓扑面积：
  131.03
• 氢给体数：
  4.0
• 氢受体数：
  6.0

反应信息

• 作为产物：
  描述：

  桑色素 在 加尔万氧基自由基 作用下， 以 乙醇 为溶剂， 生成 morin radical
  参考文献：
  名称：

  Kinetic and Stoichiometric Assessment of the Antioxidant Activity of Flavonoids by Electron Spin Resonance Spectroscopy

  摘要：

  dThere is current interest in the use of naturally occurring flavonoids as antioxidants for the preservation of foods and the prevention of diseases such as atherosclerosis and cancers. To establish the molecular characteristics required for maximum antioxidant activity, electron spin resonance (ESR) spectroscopy has been used to determine the stoichiometry and kinetics of the hydrogen-donating ability of 15 flavonoids and D-alpha-tocopherol to galvinoxyl, a resonance-stabilized, sterically protected aryloxyl radical. The second-order reaction rates, which will be governed by O-H bond dissociation energies, were myricetin > morin > quercetin > fisetin similar to catechin > kaempferol similar to luteolin > rutin > D-alpha-tocopherol > taxifolin > tamarixetin > myricetin 3',4',5'-trimethyl ether > datiscetin > galangin > hesperitin similar to apigenin. Reactivity is highly dependant on the configuration of OH groups on the flavonoid B and C rings, there being little contribution from the A ring to antioxidant effectiveness. Highest reaction rates and stoichiometries were observed with flavonols capable of being oxidized to orthoquinones or extended paraquinones. However, rates and stoichiometries did not always correlate and the data suggest that kinetic factors may be of greater importance within a biological context.

  DOI：

  10.1021/jf025922v

文献信息

• Flavonoids as Antioxidants
  作者：Slobodan V. Jovanovic、Steen Steenken、Mihajlo Tosic、Budimir Marjanovic、Michael G. Simic

  DOI：10.1021/ja00090a032

  日期：1994.6

  Spectral, acid-base, and redox properties of the phenoxyl radicals derived from 3,4-dihydroxybenzene derivatives and selected flavonoids were studied by pulse radiolysis of aqueous solutions. From the pH-dependent changes in the phenoxyl spectra, the dissociation constants were derived. The pK(a), values for the deprotonation of the 3'-OH group in the catechin (pK(a) = 4.6) and rutin (pK(a) = 4.3) radicals are similar to the pK(a) value of the 3,4-dihydroxybenzoate radicals, pK(a) = 4.2, which is expected from their similar electronic structures. Deprotonation of 5- and 7-OH in the catechin and rutin and of 5-OH in the hesperidin radicals has no effect on the radical spectra, which is explained by the inefficient coupling of the A-ring of the flavonoid radicals with the unpaired electron. Because of favorable reduction potentials of the phenoxyl radicals, E(7) = 0.56-0.7 V vs NHE, flavonoids may act as efficient antioxidants of alkylperoxyl and superoxide/hydroperoxyl radicals. The ac kinetic conductivity method was developed for the measurements of the low reaction rate constants of the superoxide radical reactions with flavonoids and phenols in aqueous solutions at pH 10. The rates of the superoxide radical reactions with flavonoids, k = 3 X 10(2)-5.1 X 10(4) M(-1) s(-1), depend on the redox properties and the charge of the flavonoids. The highest rates are measured for the oxidation of quercetin and rutin, whereas the lowest are those for the B-ring monosubstituted derivatives, with substantially higher redox potentials. Uncharged catechin at pH 7 reacts at k = 6.6 X 10(4) M(-1) s(-1), whereas the rate at pH 10, where catechin is doubly negatively charged, is approximately 4 times lower, k = 1.8 x 10(4) M(-1) s(-1). The activation parameters of the oxidation of rutin and trolox at pH 10 and methyl gallate at pH 7 were determined in an attempt to understand why the rates of the superoxide reactions are low despite high driving forces of Delta E greater than or equal to 0.4 V. Low activation enthalpies, Delta H-double dagger = 2.3-3.6 kcal/mol, and negative activation entropies, Delta S-double dagger = -25-28 cal/(mol K), point to an inner-sphere electron-transfer mechanism.
• Kinetic and Stoichiometric Assessment of the Antioxidant Activity of Flavonoids by Electron Spin Resonance Spectroscopy
  作者：Donald B. McPhail、Richard C. Hartley、Peter T. Gardner、Garry G. Duthie

  DOI：10.1021/jf025922v

  日期：2003.3.1

  dThere is current interest in the use of naturally occurring flavonoids as antioxidants for the preservation of foods and the prevention of diseases such as atherosclerosis and cancers. To establish the molecular characteristics required for maximum antioxidant activity, electron spin resonance (ESR) spectroscopy has been used to determine the stoichiometry and kinetics of the hydrogen-donating ability of 15 flavonoids and D-alpha-tocopherol to galvinoxyl, a resonance-stabilized, sterically protected aryloxyl radical. The second-order reaction rates, which will be governed by O-H bond dissociation energies, were myricetin > morin > quercetin > fisetin similar to catechin > kaempferol similar to luteolin > rutin > D-alpha-tocopherol > taxifolin > tamarixetin > myricetin 3',4',5'-trimethyl ether > datiscetin > galangin > hesperitin similar to apigenin. Reactivity is highly dependant on the configuration of OH groups on the flavonoid B and C rings, there being little contribution from the A ring to antioxidant effectiveness. Highest reaction rates and stoichiometries were observed with flavonols capable of being oxidized to orthoquinones or extended paraquinones. However, rates and stoichiometries did not always correlate and the data suggest that kinetic factors may be of greater importance within a biological context.