<prompt> Melatonin is derived fromTyrosineTryptophanGlutathioneNone  <response>: Tryptophan is first hydroxylated by tryptophan Hydroxylase 5-hydroxytryptophan is decarboxylated to serotoninSerotonin is acetylated Fuher methylated with the help of S adenosylmethionine SAMRef: DM Vasudevan, 7th edition, page no: 241, fig 18.10 