AIMS: A prophylactic use of melatonin as an anti-ageing drug has recently gained public interest due to its radical scavenging property in vitro. The present study was designed to investigate a possible antiatherogenic effect of melatonin and its physiological metabolites by examining their action on the radical-initiated formation of oxidized LDL, which is known to possess a high atherogenic potency. The metabolites investigated were the precursors serotonin and N-acetyl-serotonin and the main breakdown product 6-hydroxymelatonin. METHODS: The effect of the test substances on the in vitro oxidation of LDL (increase in conjugated diene formation) was investigated at concentrations of 1, 5, and 10 microM. RESULTS: Melatonin increased the lag time of formation of oxidized LDL only at a concentration of 10 microM. In contrast, 6-hydroxymelatonin, serotonin and N-acetylserotonin as well as vitamin E showed inhibitory effects starting at 1 microM. Thus the antioxidative action of melatonin was negligible compared with the effect of its main metabolite, its precursors and of vitamin E. CONCLUSIONS: The present results indicate that the pineal hormone melatonin appears to have little antiatherogenic property as regards the oxidation of LDL. Its main breakdown product 6-hydroxymelatonin, however, inhibits LDL-oxidation comparable to vitamin E. The precursors of melatonin, N-acetyl-serotonin and serotonin may also play a role in the inhibition of LDL oxidation in vivo.
AIMS: A prophylactic use of melatonin as an anti-ageing drug has recently gained public interest due to its radical scavenging property in vitro. The present study was designed to investigate a possible antiatherogenic effect of melatonin and its physiological metabolites by examining their action on the radical-initiated formation of oxidized LDL, which is known to possess a high atherogenic potency. The metabolites investigated were the precursors serotonin and N-acetyl-serotonin and the main breakdown product 6-hydroxymelatonin. METHODS: The effect of the test substances on the in vitro oxidation of LDL (increase in conjugated diene formation) was investigated at concentrations of 1, 5, and 10 microM. RESULTS:Melatonin increased the lag time of formation of oxidized LDL only at a concentration of 10 microM. In contrast, 6-hydroxymelatonin, serotonin and N-acetylserotonin as well as vitamin E showed inhibitory effects starting at 1 microM. Thus the antioxidative action of melatonin was negligible compared with the effect of its main metabolite, its precursors and of vitamin E. CONCLUSIONS: The present results indicate that the pineal hormone melatonin appears to have little antiatherogenic property as regards the oxidation of LDL. Its main breakdown product 6-hydroxymelatonin, however, inhibits LDL-oxidation comparable to vitamin E. The precursors of melatonin, N-acetyl-serotonin and serotonin may also play a role in the inhibition of LDL oxidation in vivo.
Authors: Sergio Millán-Plano; Eduardo Piedrafita; Francisco J Miana-Mena; Lorena Fuentes-Broto; Enrique Martínez-Ballarín; Laura López-Pingarrón; María A Sáenz; Joaquín J García Journal: Int J Mol Sci Date: 2010-01-21 Impact factor: 5.923
Authors: Andrzej T Slominski; Konrad Kleszczyński; Igor Semak; Zorica Janjetovic; Michał A Zmijewski; Tae-Kang Kim; Radomir M Slominski; Russel J Reiter; Tobias W Fischer Journal: Int J Mol Sci Date: 2014-09-30 Impact factor: 5.923