Reiter R J, Tan D X, Cabrera J, D'Arpa D
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284, USA.
Adv Exp Med Biol. 1999;467:379-87. doi: 10.1007/978-1-4615-4709-9_48.
Several tryptophan derivatives function as free radical scavengers and antioxidants. The molecule that has been most widely investigated in this regard is N-acetyl-5-methoxytryptamine (melatonin); however, pinoline (6-methoxy-1,2,3,4-tetrahydro-beta-carboline) and N-acetylserotonin also possess free radical scavenging activity. Experimental studies have shown that melatonin directly scavenges the hydroxy radical, peroxyl radical, peroxynitrite anion, and singlet oxygen. Furthermore, this tryptophan derivative stimulates a number of antioxidative enzymes and stabilizes cell membranes; this latter action helps membranes to resist free radical damage. While the antioxidative actions of most molecules are limited by their specific intracellular distribution, e.g., vitamin E in lipid-rich membranes, melatonin's antioxidative actions include the protection of lipids in the cell membrane, proteins in the cytosol, and DNA in the nucleus. Furthermore, melatonin crosses all morphophysiological barriers and enters equally well all cells in the organism.
几种色氨酸衍生物具有自由基清除剂和抗氧化剂的功能。在这方面研究最广泛的分子是N-乙酰-5-甲氧基色胺（褪黑素）；然而，松果林（6-甲氧基-1,2,3,4-四氢-β-咔啉）和N-乙酰血清素也具有自由基清除活性。实验研究表明，褪黑素能直接清除羟基自由基、过氧自由基、过氧亚硝酸盐阴离子和单线态氧。此外，这种色氨酸衍生物能刺激多种抗氧化酶并稳定细胞膜；后一种作用有助于细胞膜抵抗自由基损伤。虽然大多数分子的抗氧化作用受到其特定细胞内分布的限制，例如富含脂质的膜中的维生素E，但褪黑素的抗氧化作用包括保护细胞膜中的脂质、细胞质中的蛋白质和细胞核中的DNA。此外，褪黑素能穿过所有形态生理屏障，并能同样良好地进入机体的所有细胞。
