5-Methoxytryptamine-d4 (O-Methylserotonin-d4) is the deuterium labeled 5-Methoxytryptamine (HY-W015169). 5-Methoxytryptamine, a metabolite of Melatonin, is a nonselective 5-HT receptor agonist. 5-Methoxytryptamine has no affinity for the 5-HT3 receptor. 5-Methoxytryptamine is also a potent antioxidant and has radioprotective action[1][2][3].