title: Melatonin and its precursors scavenge nitric oxide.
abstract: Nitric oxide (NO) scavenging activity of melatonin, N-acetyl-5-hydroxytryptamine, serotonin, 5-hydroxytryptophan and L-tryptophan was examined by the Griess reaction using flow injection analysis. 1-Hydroxy-2-oxo-3-(N-methyl-3-aminopropyl)-3-methyl-1-triazene (NOC-7) was used as NO generator. The Griess reagent stoichiometrically reacts with NO2-, which was converted by a cadmium-copper reduction column from the stable end products of NO oxidation. Except for tryptophan, all the compounds examined scavenged NO in a dose-dependent manner. Melatonin, which has a methoxy group in the 5-position and an acetyl side chain, exhibited the most potent scavenging activity among the compounds tested. Serotonin, N-acetyl-5-hydroxytryptamine, and 5-hydroxytryptophan, respectively, showed moderate scavenging activity compared to melatonin. Tryptophan, which has neither a methoxy nor a hydroxyl group in the 5-position, exhibited the least NO scavenging activity.
authors.affiliation: Department of Molecular and Cell Biology, University of California at Berkeley, 94720-3200, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Noda
authors.forename: A
authors.initials: A
authors.lastname: Mori
authors.forename: R
authors.initials: R
authors.lastname: Liburdy
authors.forename: L
authors.initials: L
authors.lastname: Packer
mesh_terms: D006916:5-Hydroxytryptophan / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D016166:Free Radical Scavengers; D006834:Hydrazines / Q000737:chemistry; D007202:Indicators and Reagents; D007700:Kinetics; D008550:Melatonin / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry*; D020030:Nitric Oxide Donors / Q000737:chemistry; D010084:Oxidation-Reduction; D012701:Serotonin / Q000031:analogs & derivatives / Q000737:chemistry; D014364:Tryptophan / Q000737:chemistry
chemical_list: C115239:3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamine; D016166:Free Radical Scavengers; D006834:Hydrazines; D007202:Indicators and Reagents; D020030:Nitric Oxide Donors; D002104:Cadmium; D009569:Nitric Oxide; D012701:Serotonin; D003300:Copper; D014364:Tryptophan; D006916:5-Hydroxytryptophan; D008550:Melatonin; C006389:N-acetylserotonin