Reiter R J, Tan D X, Cabrera J, D'Arpa D, Sainz R M, Mayo J C, Ramos S
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio, Tex. 78284-7762, USA.
Biol Signals Recept. 1999 Jan-Apr;8(1-2):56-63. doi: 10.1159/000014569.
Melatonin is now known to be a multifaceted free radical scavenger and antioxidant. It detoxifies a variety of free radicals and reactive oxygen intermediates including the hydroxyl radical, peroxynitrite anion, singlet oxygen and nitric oxide. Additionally, it reportedly stimulates several antioxidative enzymes including glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and superoxide dismutase; conversely, it inhibits a prooxidative enzyme, nitric oxide synthase. Melatonin also crosses all morphophysiological barriers, e.g., the blood-brain barrier, placenta, and distributes throughout the cell; these features increase the efficacy of melatonin as an antioxidant. Melatonin has been shown to markedly protect both membrane lipids and nuclear DNA from oxidative damage. In every experimental model in which melatonin has been tested, it has been found to resist macromolecular damage and the associated dysfunction associated with free radicals.
褪黑素现在被认为是一种多方面的自由基清除剂和抗氧化剂。它能使多种自由基和活性氧中间体解毒，包括羟基自由基、过氧亚硝酸盐阴离子、单线态氧和一氧化氮。此外，据报道它能刺激几种抗氧化酶，包括谷胱甘肽过氧化物酶、谷胱甘肽还原酶、葡萄糖-6-磷酸脱氢酶和超氧化物歧化酶；相反，它抑制一种促氧化酶，一氧化氮合酶。褪黑素还能穿过所有形态生理屏障，如血脑屏障、胎盘，并分布于整个细胞；这些特性提高了褪黑素作为抗氧化剂的功效。褪黑素已被证明能显著保护膜脂质和核DNA免受氧化损伤。在每一个测试褪黑素的实验模型中，都发现它能抵抗与自由基相关的大分子损伤和功能障碍。
