The kynurenine pathway catabolite 3-hydroxykynurenine (3HK) and redox-active metals such as copper and iron are implicated in cataractogenesis. Here we investigate the reaction of kynurenine pathway catabolites with copper and iron, as well as interactions with the major lenticular structural proteins, the alpha-crystallins. The o-aminophenol kynurenine catabolites 3HK and 3-hydroxyanthranilic ...

Tryptophan metabolism plays a key role in several (patho)physiological conditions. In order to study the clinical importance of tryptophan and its predominant metabolites (kynurenines), it is important to be able to measure large series of samples with high accuracy and reliability. We aimed to develop a high-throughput on-line solid-phase extraction-liquid chromatographic-tandem mass spectrome...

The conversion of kynurenine to kynurenic acid was observed in intact animals by Kotake (2) in 1931. This reaction was studied in vitro by Mason and Berg (3, 4), who observed that slices and homogenates of rat liver converted both tryptophan and kynurenine to kynurenic acid. Similar preparations from rat kidney did not convert tryptophan to kynurenine or kynurenic acid, but had a somewhat great...

The conversion of kynurenine to kynurenic acid was observed in intact animals by Kotake (2) in 1931. This reaction was studied in vitro by Mason and Berg (3, 4), who observed that slices and homogenates of rat liver converted both tryptophan and kynurenine to kynurenic acid. Similar preparations from rat kidney did not convert tryptophan to kynurenine or kynurenic acid, but had a somewhat great...

Glutamate receptors sensitive to N-methyl-D-aspartate (NMDA) are involved in embryonic brain development but their activity may be modulated by the kynurenine pathway of tryptophan metabolism which includes an agonist (quinolinic acid) and an antagonist (kynurenic acid) at these receptors. Our previous work has shown that prenatal inhibition of the pathway produces abnormalities of brain develo...

BACKGROUND Changes in tryptophan metabolism through the vitamin B-6-dependent kynurenine pathway have been linked to activation of the immune system. OBJECTIVE We hypothesized that blood concentrations of tryptophan and its catabolites were associated with biomarkers relevant to inflammatory processes in healthy noninflamed subjects. METHODS Healthy young adults (n = 737) aged 18-28 y witho...

In the mouse hippocampus normal levels of kynurenic acid (KYNA), a neuroactive metabolite synthesized in astrocytes primarily by kynurenine aminotransferase II (KAT II)-catalyzed transamination of L-kynurenine, maintain a degree of tonic inhibition of 7 nicotinic acetylcholine receptors (nAChRs). The present in vitro study was designed to test the hypothesis that 7 nAChR activity decreases when...

The effects of certain long-term hormonal treatments of male and female rats on the activities of several enzymes involved in kynurenine synthesis and degradation were determined to further rationalize previously observed sex differences . Treatment causing elevated tryptophan oxygenase activities (corticosteroid administration) did not cronsistently result in changes of kynurenine hydrolaxe an...

Rhythmicity of tryptophan metabolism via the kynurenine pathway has been demonstrated in man. Normal subjects given 3 g of tryptophan at 0900 hours excreted almost three times the quantity of kynurenine, kynurenic acid, and xanthurenic acid than did subjects given the same dose at 2100 hours. Other metabolites of the kynurenine pathway varied in the same fashion but with lesser magnitude. In co...