ABSTRACT
Melatonin is an indolamine hormone (N-acetyl-5-methoxytryptamine) synthesized from the essential amino acid tryptophan in a series of four enzymatic steps.1,2 It was originally discovered in 1958 by the American dermatologist Aaron Lerner and his coworkers at the Yale University School of Medicine as an amphibian skin-lighting factor present in extracts of bovine pineal glands. Lerner named the molecule “melatonin” because it induces contraction of stellate amphibian melanophores.3 The fact that melatonin is an evolutionarily highly conserved molecule, ubiquitously distributed in living systems, seems to demonstrate that it has important physiological roles.4
