6-hydroxy Melatonin is an active metabolite of melatonin .1,2,3,4,5 It is formed from melatonin by the cytochrome P450 (CYP) isoform CYP1A2 in human liver microsomes.6 6-hydroxy Melatonin is a melatonin 1A (MT1A), MT1B, and MT2 receptor agonist.1,2 It inhibits dopamine release from isolated rabbit retina (IC50 = 0.0016 ?M).3 6-hydroxy Melatonin (10 and 100 ?M) reduces increases in the levels of NF-κB, IL-6, and IL-8 and decreases in glutathione (GSH) levels in LPS- and peptidoglycan G-stimulated human umbilical vein endothelial cells (HUVECs) in an in vitro model of sepsis.4 It reduces iron-induced lipid oxidation in rat hippocampal homogenate when administered at a dose of 10 mg/kg.5
1.Dubocovich, M.L., Masana, M.I., Iacob, S., et al.Melatonin receptor antagonists that differentiate between the human Mel1a and Mel1b recombinant subtypes are used to assess the pharmacological profile of the rabbit retina ML1 presynaptic heteroreceptorNaunyn-Schmiedeberg's Arch. Pharmacol.355(3)365-375(1997) 2.Dubocovich, M.L.Melatonin receptors: Are there multiple subtypes?Trends Pharamacol. Sci.16(2)50-56(1995) 3.Dubocovich, M.L.Characterization of a retinal melatonin receptorJ. Pharmacol. Exp. Ther.234(2)395-401(1985) 4.Lowes, D.A., Almawash, A.M., Webster, N.R., et al.Melatonin and structurally similar compounds have differing effects on inflammation and mitochondrial function in endothelial cells under conditions mimicking sepsisBr. J. Anaesth.107(2)193-201(2011) 5.Maharaj, D.S., Maharaj, H., Daya, S., et al.Melatonin and 6-hydroxymelatonin protect against iron-induced neurotoxicityJ. Neurochem.96(1)78-81(2006) 6.H?rtter, S., Wang, X., Weigmann, H., et al.Differential effects of fluvoxamine and other antidepressants on the biotransformation of melatoninJ. Clin. Psychopharmacol.21(2)167-174(2001)