Whayne Thomas F, Saha Sibu P, Mukherjee Debabrata
326 Wethington Building, 900 South Limestone Street, Lexington, KY 40536-020.
Cardiovasc Hematol Disord Drug Targets. 2016;16(1):13-20. doi: 10.2174/1871529x16666160614015533.
Antioxidants offer protection against the damage potentially caused by free radicals, which usually involve an oxygen or nitrogen moiety, in living organisms. An antioxidant can be defined as a molecule that has the capability to inhibit the oxidation of another molecule, so, in other words, it is a reducing agent that is sufficiently stable to donate an electron to a circulating free radical and thereby result in its neutralization. Free radicals can be defined as any chemical species that has one or more mismatched electrons; these free radicals can cause a sequential reaction resulting in damage to multiple components of the organism, functioning either as an oxidant or a reductant by accepting or donating an electron, respectively. Oxidative stress can be defined as an imbalance between the production of free radicals and necessary antioxidant defenses. Therefore protection of the organism from these potentially damaging entities, when appropriate, is essential. Potential damage involves lipids, proteins, cell membranes, deoxyribonucleic acid (DNA), carbohydrates, and various enzymes, which can lead to cell death. Antioxidant protection from free radical-induced damage occurs via the donation of an electron with subsequent conversion of a free radical to a harmless chemical configuration that can no longer damage a cell and its components. Classes of antioxidants include, natural, nutrient, and supplemental. When antioxidant levels are low, there is a resultant increase in oxidative stress with a harmful increase in free radicals that can be associated with an increased risk for cardiovascular (CV) disease including atherosclerosis, various inflammatory diseases, and cancer. Major issues for the clinician to consider are what can be done to naturally increase antioxidants when deficient or when a directed increase might be beneficial such as in aging and degenerative disease, how nutrients can be altered or provided to increase antioxidant protection, and when or if to consider the use of supplements, frequently classified as alternative medicines.
抗氧化剂可保护生物体免受自由基可能造成的损害，自由基通常含有氧或氮部分。抗氧化剂可定义为具有抑制另一分子氧化能力的分子，也就是说，它是一种足够稳定的还原剂，能够向循环中的自由基提供一个电子，从而使其中和。自由基可定义为任何具有一个或多个未配对电子的化学物质；这些自由基可引发连锁反应，导致生物体的多个组成部分受损，它们分别通过接受或提供一个电子而作为氧化剂或还原剂发挥作用。氧化应激可定义为自由基产生与必要的抗氧化防御之间的失衡。因此，在适当的时候保护生物体免受这些潜在的破坏因素的影响至关重要。潜在的损害涉及脂质、蛋白质、细胞膜、脱氧核糖核酸（DNA）、碳水化合物和各种酶，这可能导致细胞死亡。抗氧化剂对自由基诱导损伤的保护作用是通过提供一个电子，随后将自由基转化为无害的化学构型来实现的，这种构型不再能损害细胞及其组成部分。抗氧化剂的类别包括天然的、营养性的和补充性的。当抗氧化剂水平较低时，氧化应激会随之增加，自由基有害增加，这可能与心血管（CV）疾病（包括动脉粥样硬化）、各种炎症性疾病和癌症的风险增加有关。临床医生需要考虑的主要问题是，当抗氧化剂缺乏时或在诸如衰老和退行性疾病等情况下定向增加抗氧化剂可能有益时，如何通过自然方式增加抗氧化剂；如何改变或提供营养物质以增强抗氧化保护；以及何时或是否考虑使用通常归类为替代药物的补充剂。
