Melatonin (N-Acetyl-5-methoxytrptamine) is a biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the pineal gland. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of sleep, mood and reproduction. Melatonin is also an effective antioxidant. (1-6)

The Pantex Direct Salivary Melatonin EIA kit, Cat #634, is based on the competition principal and microplate separation. Melatonin in standards (calibrators) and samples compete with a fixed amount of melatonin conjugated to horse radish peroxidase (Melatonin-HRP) for binding sites with a rabbit melatonin monoclonal antiserum bound to GARGG (goat anti-rabbit gamma globulin) coated wells of a microplate. After incubation, unbound components are washed away, enzyme substrate solution is added and a blue color formed. This reaction is stopped with an acid solution to produce a yellow color. The optical density is then read at 450 nm. The amount of Melatonin-HRP detected is inversely proportional to the amount of melatonin in a sample.