6 Hydroxymelatonin

6-Hydroxymelatonin (6-OHM) is a naturally occurring, endogenous, major active metabolite of the neurotransmitter melatonin. Similar to melatonin, 6-OHM is a full agonist of the MT₁ and MT₂ receptors. It is also an antioxidant and neuroprotective, and is even more potent in this regard relative to melatonin.