Maharaj Deepa S, Glass Beverley D, Daya Santy
Faculty of Pharmacy, Rhodes University, P.O. Box 94, Grahamstown, 6140, South Africa.
Biosci Rep. 2007 Dec;27(6):299-320. doi: 10.1007/s10540-007-9052-1.
The fact that the full extent of the function of the pineal gland has not yet been elucidated, has stimulated melatonin research worldwide. This review introduces melatonin's mechanism of action, direct and indirect antioxidant actions as well as the antioxidant properties of its metabolites, 6-hydroxymelatonin (6-OHM) and N-acetyl-N-formyl-5-methoxykynurenamine (AFMK). At present the mechanism of action is proposed to be receptor-, protein- and nonprotein-mediated. From its popular role in the treatment of jetlag, melatonin is now implicated in the reduction of oxidative stess, both as a free radical scavenger and antioxidant. Melatonin's direct scavenging action in respect of the following will be discussed: superoxide anions, hydrogen peroxide, hydroxyl radicals, singlet oxygen, peroxy radicals and nitric oxide/peroxy nitrite anions. In addition melatonin also possesses indirect antioxidant activity and the role of its metabolites, AFMK and 6-OHM will be presented. It is these free radical scavenging and antioxidant properties of melatonin that has shifted the focus from that of merely strengthening circadian rhythms to that of neuroprotectant: a new place in therapy.
松果体功能的全部范围尚未阐明这一事实，激发了全球范围内对褪黑素的研究。本综述介绍了褪黑素的作用机制、直接和间接抗氧化作用以及其代谢产物6-羟基褪黑素（6-OHM）和N-乙酰-N-甲酰-5-甲氧基犬尿胺（AFMK）的抗氧化特性。目前，其作用机制被认为是受体介导、蛋白质介导和非蛋白质介导的。从其在治疗时差反应中的广泛作用来看，褪黑素现在被认为在减轻氧化应激方面发挥作用，既是自由基清除剂又是抗氧化剂。将讨论褪黑素在以下方面的直接清除作用：超氧阴离子、过氧化氢、羟基自由基、单线态氧、过氧自由基以及一氧化氮/过氧亚硝酸根阴离子。此外，褪黑素还具有间接抗氧化活性，并将介绍其代谢产物AFMK和6-OHM的作用。正是褪黑素的这些自由基清除和抗氧化特性，将研究重点从仅仅加强昼夜节律转移到了神经保护剂方面：在治疗中占据了新的地位。
