Singh Pankaj K, Krishnan Sunil
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Evid Based Complement Alternat Med. 2015;2015:741301. doi: 10.1155/2015/741301. Epub 2015 Aug 20.
The potentially life-threatening effects of total body ionizing radiation exposure have been known for more than a century. Despite considerable advances in our understanding of the effects of radiation over the past six decades, efforts to identify effective radiation countermeasures for use in case of a radiological/nuclear emergency have been largely unsuccessful. Vitamin E is known to have antioxidant properties capable of scavenging free radicals, which have critical roles in radiation injuries. Tocopherols and tocotrienols, vitamin E analogs together known as tocols, have shown promise as radioprotectors. Although the pivotal mechanisms of action of tocols have long been thought to be their antioxidant properties and free radical scavenging activities, other alternative mechanisms have been proposed to drive their activity as radioprotectors. Here we provide a brief overview of the effects of ionizing radiation, the mechanistic mediators of radiation-induced damage, and the need for radiation countermeasures. We further outline the role for, efficacy of, and mechanisms of action of tocols as radioprotectors, and we compare and contrast their efficacy and mode of action with that of another well-studied chemical radioprotector, amifostine.
全身电离辐射暴露可能危及生命的影响已为人所知超过一个世纪。尽管在过去六十年里我们对辐射影响的理解有了相当大的进展，但在确定用于应对放射/核紧急情况的有效辐射防护措施方面，努力大多未取得成功。已知维生素E具有能够清除自由基的抗氧化特性，而自由基在辐射损伤中起关键作用。生育酚和生育三烯酚，统称为生育酚的维生素E类似物，已显示出作为辐射防护剂的潜力。尽管长期以来人们一直认为生育酚的关键作用机制是其抗氧化特性和自由基清除活性，但也有人提出了其他替代机制来推动它们作为辐射防护剂的活性。在此，我们简要概述电离辐射的影响、辐射诱导损伤的机制介导物以及对辐射防护措施的需求。我们进一步概述生育酚作为辐射防护剂的作用、功效和作用机制，并将它们的功效和作用方式与另一种经过充分研究的化学辐射防护剂氨磷汀进行比较和对比。
