Nukala Ujwani, Thakkar Shraddha, Krager Kimberly J, Breen Philip J, Compadre Cesar M, Aykin-Burns Nukhet
Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Joint Bioinformatics Graduate Program, University of Arkansas at Little Rock, Little Rock, AR 72204, USA.
Antioxidants (Basel). 2018 Feb 23;7(2):33. doi: 10.3390/antiox7020033.
Radiation countermeasures fall under three categories, radiation protectors, radiation mitigators, and radiation therapeutics. Radiation protectors are agents that are administered before radiation exposure to protect from radiation-induced injuries by numerous mechanisms, including scavenging free radicals that are generated by initial radiochemical events. Radiation mitigators are agents that are administered after the exposure of radiation but before the onset of symptoms by accelerating the recovery and repair from radiation-induced injuries. Whereas radiation therapeutic agents administered after the onset of symptoms act by regenerating the tissues that are injured by radiation. Vitamin E is an antioxidant that neutralizes free radicals generated by radiation exposure by donating H atoms. The vitamin E family consists of eight different vitamers, including four tocopherols and four tocotrienols. Though alpha-tocopherol was extensively studied in the past, tocotrienols have recently gained attention as radiation countermeasures. Despite several studies performed on tocotrienols, there is no clear evidence on the factors that are responsible for their superior radiation protection properties over tocopherols. Their absorption and bioavailability are also not well understood. In this review, we discuss tocopherol's and tocotrienol's efficacy as radiation countermeasures and identify the challenges to be addressed to develop them into radiation countermeasures for human use in the event of radiological emergencies.
辐射防护剂、辐射缓解剂和辐射治疗剂。辐射防护剂是在辐射暴露前施用的药物，通过多种机制保护机体免受辐射诱导的损伤，包括清除由初始放射化学事件产生的自由基。辐射缓解剂是在辐射暴露后但在症状出现前施用的药物，通过加速辐射诱导损伤的恢复和修复来发挥作用。而辐射治疗剂在症状出现后施用，通过再生受辐射损伤的组织来发挥作用。维生素E是一种抗氧化剂，通过提供氢原子来中和辐射暴露产生的自由基。维生素E家族由八种不同的维生素形式组成，包括四种生育酚和四种生育三烯酚。尽管过去对α-生育酚进行了广泛研究，但生育三烯酚最近作为辐射防护措施受到关注。尽管对生育三烯酚进行了多项研究，但尚无明确证据表明其辐射防护性能优于生育酚的原因。它们的吸收和生物利用度也没有得到很好的理解。在这篇综述中，我们讨论了生育酚和生育三烯酚作为辐射防护措施的功效，并确定了在发生放射性紧急情况时将它们开发成供人类使用的辐射防护措施需要解决的挑战。
