AMK is an active metabolite of the neurohormone melatonin .1,2,3,4 It is formed from melatonin via the metabolic intermediate AFMK that is then deformylated by catalase or formamidase.5,6 AMK scavenges singlet oxygen in vitro when used at a concentration of 200 µM.1 It inhibits the epinephrine- and arachidonic acid-induced production of prostaglandin E2 and PGD2 in ovine seminal vesicle microsomes in a concentration- and time-dependent manner, as well as LPS-induced increases in COX-2 levels in RAW 264.7 macrophages when used at a concentration of 500 µM.2,3 AMK (20 mg/kg) decreases MPTP-induced increases in lipid peroxidation in the cytosol and mitochondria from substantia nigra and striatum in a mouse model of MPTP-induced Parkinson’s disease.4
1.Schaefer, M., and Hardeland, R.The melatonin metabolite N1-acetyl-5-methoxykynuramine is a potent singlet oxygen scavengerJ. Pineal Res.46(1)49-52(2009) 2.Kelly, R.W., Amato, F., and Seamark, R.F.N-acetyl-5-methoxy kynurenamine, a brain metabolite of melatonin, is a potent inhibitor of prostaglandin biosynthesisBiochem. Biophys. Res. Commun.121(1)372-379(1984) 3.Mayo, J.C., Sainz, R.M., Tan, D.-X., et al.Anti-inflammatory actions of melatonin and its metabolites, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK) and N1-acetyl-5-methoxykynuramine (AMK), in macrophagesJ. Neuroimmunol.165(1-2)139-149(2005) 4.Tapias, V., Escames, G., LÓpez, L.C., et al.Melatonin and its brain metabolite N1-acetyl-5-methoxykynuramine prevent mitochondrial nitric oxide synthase induction in parkinsonian miceJ. Neurosci. Res.87(13)3002-3010(2009) 5.Tan, D.-X., Manchester, L.C., Reiter, R.J., et al.Melatonin directly scavenges hydrogen peroxide: A potentially new metabolic pathway of melatonin biotransformationFree Radic. Biol. Med.29(11)1177-1185(2000) 6.Hirata, F., Hayaishi, O., Tokuyama, T., et al.In vitro and in vivo formation of two new metabolites of melatoninJ. Biol. Chem.249(4)1311-1313(1974)