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The reaction of paprika carotenoids, capsanthin and capsorubin, with reactive oxygen species (ROS), such as superoxide anion radical (·O2(-)), hydroxyl radical (·OH), and singlet oxygen ((1)O2), was analyzed by LC/PDA ESI-MS and ESR spectrometry. Capsanthin formed both the 5,6-epoxide and 5,8-epoxide by reaction with ·O2(-) and ·OH. Furthermore, capsanthin also formed 5,6- and 5,8-endoperoxide on reaction with (1)O2. The same results were obtained in the case of capsanthin diacetate. On the other hand, capsorubin showed higher stability against these ROS. Capsorubin formed 7,8-epoxide on reaction with ·O2(-) and ·OH and 7,8-endoperoxide on reaction with (1)O2.
Nishino et al. (2016) studied this question.