Aruoma Okezie I
OICA International, Saint Lucia, West Indies, and Pharmacology Group, King's College London, SW3 6LX London, Great Britain.
J Am Oil Chem Soc. 1998;75(2):199-212. doi: 10.1007/s11746-998-0032-9.
Free radicals and other reactive oxygen species (ROS) are constantly formed in the human body. Free-radical mechanisms have been implicated in the pathology of several human diseases, including cancer, atherosclerosis, malaria, and rheumatoid arthritis and neurodegenerative diseases. For example, the superoxide radical (O ) and hydrogen peroxide (HO) are known to be generated in the brain and nervous system , and several areas of the human brain are rich in iron, which appears to be easily mobilizable in a form that can stimulate free-radical reactions. Antioxidant defenses to remove O and HO exist. Superoxide dismutases (SOD) remove O by greatly accelerating its conversion to HO. Catalases in peroxisomes convert HO into water and O and help to dispose of HO generated by the action of the oxidase enzymes that are located in these organelles. Other important HO-removing enzymes in human cells are the glutathione peroxidases. When produced in excess, ROS can cause tissue injury. However, tissue injury can itself cause ROS generation (e.g., by causing activation of phagocytes or releasing transition metal ions from damaged cells), which may (or may not, depending on the situation) contribute to a worsening of the injury. Assessment of oxidative damage to biomolecules by means of emerging technologies based on products of oxidative damage to DNA (e.g., 8-hydroxydeoxyguanosine), lipids (e.g., isoprostanes), and proteins (altered amino acids) would not only advance our understanding of the underlying mechanisms but also facilitate supplementation and intervention studies designed and conducted to test antioxidant efficacy in human health and disease.
自由基和其他活性氧物质（ROS）在人体中不断形成。自由基机制与多种人类疾病的病理过程有关，包括癌症、动脉粥样硬化、疟疾、类风湿性关节炎和神经退行性疾病。例如，已知超氧阴离子自由基（O ）和过氧化氢（HO）在大脑和神经系统中产生，而人类大脑的几个区域富含铁，铁似乎很容易以能刺激自由基反应的形式被调动。存在清除O 和HO的抗氧化防御机制。超氧化物歧化酶（SOD）通过极大地加速其向HO的转化来清除O 。过氧化物酶体中的过氧化氢酶将HO转化为水和O ，并有助于处理由位于这些细胞器中的氧化酶作用产生的HO。人类细胞中其他重要的清除HO的酶是谷胱甘肽过氧化物酶。当ROS产生过多时，会导致组织损伤。然而，组织损伤本身也会导致ROS生成（例如，通过引起吞噬细胞活化或从受损细胞中释放过渡金属离子），这可能（或可能不会，取决于具体情况）导致损伤恶化。通过基于DNA氧化损伤产物（例如8-羟基脱氧鸟苷）、脂质（例如异前列腺素）和蛋白质（改变的氨基酸）的新兴技术评估对生物分子的氧化损伤，不仅会增进我们对潜在机制的理解，还将促进为测试抗氧化剂在人类健康和疾病中的功效而设计和开展的补充和干预研究。
