Trolox在水中的抗羟基自由基活性:pH值对速率常数的影响

IF 1.2 Q3 MULTIDISCIPLINARY SCIENCES The EuroBiotech Journal Pub Date : 2022-04-01 DOI:10.2478/ebtj-2022-0006
Nguyen Thi Hoa
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引用次数: 1

摘要

Trolox(6-羟基-2,5,7,8-四甲基铬-2-羧酸)是一种高度亲水性的α-生育酚类似物,被广泛用作衡量其他化学物质抗氧化能力的标准,并以Trolox当量表示。然而,pH值对羟基自由基清除活性的影响尚未得到充分的研究。本实验研究了Trolox在水中的HOO•抗自由基活性。结果发现,O1-H键的h抽离决定了中性态和单阴离子态的活性,而羟基阴离子态的电子转移反应决定了阴离子态的活性。随着pH值的升高,总速率常数增大,但随着pH值的升高,由于HOO•摩尔分数的降低,Trolox + HOO•在水中的总速率常数发生变化。结果还表明,在pH < 2时,o1自由基是水中Trolox + HOO•反应的主要中间体,而在pH -gt- 5时,阴离子自由基是主要中间体。因此,速率常数和反应中间体随pH值的变化而变化。
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The hydroperoxyl antiradical activity of Trolox in water: The effects of pH values on rate constants
Abstract Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) is a highly hydrophilic α-tocopherol analog that is widely used as a standard against which the antioxidant ability of other chemicals is measured and represented in Trolox equivalents. However, the effect of pH values on the hydroxyl radical scavenging activity has not been fully studied yet. In this study, the HOO• antiradical activity of Trolox in water was studied. It was found that the H-abstraction of the O1-H bond determined the activity of the neutral and monoanion states, whereas the electron transfer reaction of the hydroxyl anion state determined the activity of the dianion state. Although the total rate constant increased following the increase in pH levels, the overall rate constant of the Trolox + HOO• reaction in water changed when pH levels rose due to the decrease in HOO• molar fraction. The results also revealed that at pH < 2, the O1-radical was the main intermediate of the Trolox + HOO• reaction in water, whereas, at pH ---gt--- 5, the anion-radical was the significant intermediate. Thus the rate constants and the reaction intermediates vary with the pH values.
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来源期刊
The EuroBiotech Journal
The EuroBiotech Journal Agricultural and Biological Sciences-Food Science
CiteScore
3.60
自引率
0.00%
发文量
17
审稿时长
10 weeks
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