Related Experiment Video
Updated: Aug 12, 2026

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development
Published on: April 15, 2013
Radical scavenging properties of tryptophan metabolites. Estimation of their radical reactivity
K Goda1, Y Hamane, R Kishimoto
1Faculty of Nutrition, Kobe Gakuin University, Japan. goda@nutr.kobegakuin.ac.jp
Abstract:
Radical scavenging properties of tryptophan metabolites were estimated using their radical reactivity. Metabolites of the kynurenine and the melatonin biosynthesis pathway were mainly examined by use of a kinetical model. Their radical reactivity was determined as the reaction rate constant with a stable free radical, such as galvinoxyl; that is a phenoxy radical. The rate constants of the metabolites have a widely ranged spectrum, which can be divided into three groups. The first group (3-hydroxykynurenine, 3-hydroxyanthranilic acid, and indole-3-pyruvic acid) is more reactive than alpha-tocopherol; the reactivity of the second group (xanthurenic acid, serotonin, N-acetylserotonin) is similar to that of butylated hydroxytoluene (BHT); the third group (kynurenic acid, melatonin, and other ones) is less reactive than BHT.
Related Concept Videos
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Radical Reactivity: Overview
Radical Reactivity: Steric Effects
Along with electronic factors, steric factors also account...
Radical Reactivity: Electrophilic Radicals
Radical Reactivity: Nucleophilic Radicals
Radical Reactivity: Intramolecular vs Intermolecular

![Radiosynthesis of 1-(2-[18F]Fluoroethyl)-L-Tryptophan using a One-pot, Two-step Protocol](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F63025.jpg&w=3840&q=50)