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

Abstract

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 [14C]melatonin 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.