Absolute identification of melatonin in human plasma and cerebrospinal fluid

Abstract

MELATONIN, the compound responsible for the lightening of amphibian skin, was extracted from bovine pineal glands and chemically characterised by Lerner et al.^1,2. Recent reviews^3–5 have suggested that melatonin has an endocrine role, particularly in relation to chronobiology, pituitary function and cerebral physiology. Most of this work has been accomplished by animal experimentation. So far the evidence for the existence of melatonin in man has been indirect. It is formed biosynthetically from tryptophan and the necessary enzyme system is known to be present in the human pineal throughout life⁷. There is however little evidence to suggest that it circulates in human blood or cerebrospinal fluid (CSF). Attempts to identify melatonin by bioassay⁸ or radioimmunoassay⁹ have not been accompanied by the chemical identification of the substance measured. We present here, for the first time, unequivocal evidence based on gas chromatography (GC) and mass spectrometry (MS) of the presence of melatonin in human plasma and CSF.