In Vitro and in Vivo Formation of Two New Metabolites of Melatonin

A partially purified enzyme from rabbit brain catalyzed the oxygenative cleavage of the pyrrole moiety of melatonin yielding Nr-acetyl-NZ-formyl-5-methoxykynurenamine, which was further degraded to NY-acetyl-5-methoxykynurenamine by the action of formamidase.Authentic samples of these two metabolites were synthesized by ozonolysis of melatonin and were shown to be indistinguishable from the enzymic products.When 14Cmelatonin was injected intracisternally, the major metabolite in the rat brain was shown to be NY-acetyl-S-methoxykynurenamine.The results indicate that these two new metabolites are involved in the major metabolic pathway of melatonin in the central nervous system.