Melatonin as an Antioxidant

항산화제로서 Melatonin

Melatonin, a chemical mediator produced in the mammalian pineal gland and several other organ, is a ubiquitously acting antioxidant. It has been shown to scavenge the hydroxyl radical (ㆍOH), singlet oxygen ($^1$O$_2$) and the peroxynitrite anion (ONOO-). In addition, melatonin reportedly stimulates a number of antioxidative enzymes including glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase. Antioxidative effect of melatonin in pharmacological and physiological level was investigated using hepatocarcinogen 2-nitropropane (2-NP) and pinealectornized (Px) rats, respectively. Lipid peroxidation (LPO) as indicated by malondialdehyde and 4-hydroxyalkenals and DNA damage as indicated by 8-hydroxydeoxyguanosine (8-OH-dG) induced by 2-NP were prevented by melatonin. The degree of LPO and DNA damage in Px rats were higher than those of intact old and young ones suggesting the removal of pineal gland resulted in higher accumulation of oxidative damage.