Focsan A Ligia, Polyakov Nikolay E, Kispert Lowell D
Department of Chemistry, Valdosta State University, Valdosta, GA 31698, USA.
Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russia.
Antioxidants (Basel). 2017 Oct 21;6(4):80. doi: 10.3390/antiox6040080.
The antioxidant astaxanthin is known to accumulate in algae under unfavorable environmental conditions for normal cell growth. The accumulated astaxanthin functions as a protective agent against oxidative stress damage, and tolerance to excessive reactive oxygen species (ROS) is greater in astaxanthin-rich cells. The detailed mechanisms of protection have remained elusive, however, our Electron Paramagnetic Resonance (EPR), optical and electrochemical studies on carotenoids suggest that astaxanthin's efficiency as a protective agent could be related to its ability to form chelate complexes with metals and to be esterified, its inability to aggregate in the ester form, its high oxidation potential and the ability to form proton loss neutral radicals under high illumination in the presence of metal ions. The neutral radical species formed by deprotonation of the radical cations can be very effective quenchers of the excited states of chlorophyll under high irradiation.
已知抗氧化剂虾青素在不利于正常细胞生长的环境条件下会在藻类中积累。积累的虾青素作为一种抗氧化应激损伤的保护剂发挥作用，富含虾青素的细胞对过量活性氧（ROS）的耐受性更强。然而，保护的详细机制仍然难以捉摸，不过我们对类胡萝卜素的电子顺磁共振（EPR）、光学和电化学研究表明，虾青素作为保护剂的效率可能与其与金属形成螯合配合物和被酯化的能力、以酯形式聚集的无能、其高氧化电位以及在金属离子存在下高光照下形成质子损失中性自由基的能力有关。由自由基阳离子去质子化形成的中性自由基物种在高辐照下可以是叶绿素激发态的非常有效的猝灭剂。
