Year-end Sale % OFF 
Abstract
The effect of vitamin B-6 deficiency on excretion of tryptophan metabolites was compared in rats, guinea pigs, hamsters, and humans. With adequate vitamin B-6 intake, a high percentage of the tryptophan administered was excreted as kynurenic acid and quinolinic acid in rat urine, and as acetylkynurenine and kynurenine in hamster urine. None of the tryptophan metabolites measured in normal guinea pig urine or human urine accounted for more than 1% to 2% of the tryptophan administered. During vitamin B-6 deficiency, the percentages of the tryptophan load excreted as xanthurenic acid, kynurenine, and o-hydroxykynurenine, (which precede the 3-hydroxykynureninase step in the kynurenine pathway) were increased in all four species. However, the percentages excreted as 3-hydroxyanthranilic acid and quinolinic acid, which are beyond the 3-hydroxy-kynureninase step, responded differently. The 3-hydroxyanthranilic acid percentage was not changed in rat urine, but was increased in human and guinea pig urines. The quinolinic acid percentage was decreased in rat urine, unchanged in guinea pig and hamster urine, and increased in human urine. In rats, depression of 3-hydroxykynureninase activity was apparently the major factor causing a change in the pattern. However, in hamsters, kynurenine hydroxylase and o-hydroxykynureninanse activities apparently were depressed. In humans, 3-hydroxykynureninase activity also was apparently depressed and the total amount of administered tryptophan accounted fro in the urine as metabolites of the kynurenine pathway was increased. Levels of urinary metabolites reached a maximum in guinea pigs after only 1 week of consuming the vitamin B-6 deficient diet, suggesting that the vitamin deficiency developed very rapidly in this species.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
