The urinary ratio of 3-hydroxykynurenine/3-hydroxyanthranilic acid is an index to predicting the adverse effects of D-tryptophan in rats.
J Nutr Sci Vitaminol (Tokyo)
; 60(4): 261-8, 2014.
Article
in En
| MEDLINE
| ID: mdl-25297615
ABSTRACT
The adverse effects of D-tryptophan and the possibility of it being a surrogate index for predicting adverse effects in rats were investigated. Male rats were fed one of several test diets (20% casein diets with 0% (control), 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% D-tryptophan) for 21 d, and 24-h urine samples on the final day of the experiment were collected. Analyses of food intake and body-weight changes revealed adverse effects to be observed in the group fed the 0.3% D-tryptophan diet. We propose urinary levels of 3-hydroxykynurenine/3-hydroxyanthranilic acid to be surrogate indicators for predicting the adverse effects of D-tryptophan from the break point of body-weight gains and urinary levels of D-tryptophan metabolites. The reaction 3-hydroxykynurenineâ3-hydroxyanthranilic acid is catalyzed by the pyridoxal phosphate-dependent enzyme kynureninase. Increasing urinary 3-hydrokykynurenine indicates kynureninase deficiency. Intake of D-tryptophan in rats fed the 0.3% D-tryptophan diet was 0.21 g/kg body weight and feeding of the 0.3% D-tryptophan diet did not elicit adverse effects. Thus, the safe level of D-tryptophan was less than 0.2% in the diet, 0.15 g/kg body weight, in rats.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Tryptophan
/
Diet
/
Amino Acid Metabolism, Inborn Errors
/
Hydrolases
/
3-Hydroxyanthranilic Acid
/
Kynurenine
Type of study:
Prognostic_studies
/
Risk_factors_studies
Limits:
Animals
Language:
En
Journal:
J Nutr Sci Vitaminol (Tokyo)
Year:
2014
Document type:
Article