Influence of pH on the decay of β-carotene radical cation in aqueous Triton X-100: A laser flash photolysis study
Influence of pH on the decay of β-carotene radical cation in aqueous Triton X-100: A laser flash photolysis study
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pH 对 Triton X-100 水溶液中 β-胡萝卜素自由基阳离子衰变的影响：激光闪光光解研究
DOI：
10.1016/j.jphotobiol.2015.02.026
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Tomoyoshi Suenobu and Shunichi Fukuzumi
中科院分区：
文献类型：
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作者：
Ali El-Agamey;Maha A. El-Hagrasy;Tomoyoshi Suenobu and Shunichi Fukuzumi
识别类胡萝卜素中性自由基的光谱信息对于研究它们对O2的反应能力，从而评估它们在相应类胡萝卜素的抗氧化剂-促氧化性能中的作用是必不可少的。最近，有报道称β-胡萝卜素中性自由基(β-CAR自由基点)在750nm处有最大吸收。这与许多报告的结果相矛盾，这些报告表明，类胡萝卜素中性自由基(CAR自由基点)吸收的光谱区域与其母类胡萝卜素相同或接近。本文研究了在2%曲拉通X-100(TX-100)水溶液中，pH对β-胡萝卜素自由基阳离子(β-CAR-H自由基圆点+)衰变的影响，并用激光闪光光解与动力学吸收光谱相结合的方法，确定了β-胡萝卜素中性自由基的吸收带。通过增加溶液的pH值，β-CAR-H自由基点+的衰变被增强，这种增强与550-900 nm范围内任何正吸收带的形成无关。通过将这些结果与文献进行比较，可以得出结论，β-胡萝卜素中性自由基最有可能在与β-胡萝卜素相同的光谱范围内被吸收。讨论了β-CAR-H自由基Dot+与−-OH反应的反应途径。
The identification of the spectral information of carotenoid neutral radicals is essential for studying their reactivities towards O2and thereby evaluating their role in the antioxidant–prooxidant properties of the corresponding carotenoid. Recently, it was reported that β-carotene neutral radical (β-CARradical dot) has an absorption maximum at 750 nm. This contradicts the results of many reports that show carotenoid neutral radicals (CARradical dot) absorb in the same or near to the spectral region as their parent carotenoids. In this manuscript, the influence of pH on the decay of β-carotene radical cation (β-CAR-Hradical dot+), generated in an aqueous solution of 2% Triton X-100 (TX-100), was investigated, employing laser flash photolysis (LFP) coupled with kinetic absorption spectroscopy, to identify the absorption bands of the β-carotene neutral radicals. By increasing the pH value of the solution, the decay of β-CAR-Hradical dot+is enhanced and this enhancement is not associated with the formation of any positive absorption bands over the range 550–900 nm. By comparing these results with the literature, it can be concluded that β-carotene neutral radicals most probably absorb within the same spectral range as that of β-carotene. The reaction pathways of the reaction of β-CAR-Hradical dot+with−OH have been discussed.