Testing the Functional Capacity of the Tryptophan-Niacin Pathway in Man by Analysis of Urinary Metabolites

Price, J. M.; Brown, R. R.; Yess, Norma

doi:10.1016/b978-1-4831-6750-3.50009-3

Cited by 108 publications

(44 citation statements)

References 195 publications

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“…It should be noted that the various tryptophan metabolites differ in the time required for optimum color development in the diazotization and coupling reaction. Color development in the automated method is recorded after a relatively brief but consistent reaction time in contrast to the manual method of Price, Brown, and Yess (6) in which color development is allowed to become maximal. For this reason the total "diazo reactant" measured by the automated technique is not mathematically comparable to the sum of the individual metabolites measured by the manual method.…”

Section: Resultsmentioning

confidence: 99%

Circadian periodicity of tryptophan metabolism

Rapoport¹,

Beisel²

1968

J. Clin. Invest.

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Section: Resultsmentioning

confidence: 99%

Circadian periodicity of tryptophan metabolism

Rapoport¹,

Beisel²

1968

J. Clin. Invest.

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“…Price et al have reported that the amounts of KA in urine of health adults were 13.3 ± 4.0 μmol day -1 in males and 13.2 ± 1.8 μmol day -1 in females. 20 Accordingly, the HRP method may be applied to the determination of KA in human urine sample, although the pretreatment, such as the concentration of urine sample or the extraction of KA from urine sample, should be required.…”

Section: Application To the Determination Of Ka In Seramentioning

confidence: 99%

Spectrofluorometric Determination of Kynurenic Acid with Horseradish Peroxidase in the Presence of Hydrogen Peroxide

2007

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The catalytic activity of horseradish peroxidase (HRP) in the presence of hydrogen peroxide has been investigated for the fluorescent derivatization of kynurenic acid under conditions with no exposure to light. Non-fluorescent kynurenic acid was converted into a fluorescent compound (Ex: 367 nm, Em: 470 nm) with HRP in the presence of hydrogen peroxide, and the optimum conditions of this fluorescent derivatization were investigated. Moreover, this fluorescent derivatization was developed for a spectrofluorometric determination of trace amounts of kynurenic acid by measuring the fluorescence intensity of the fluorescent compound. The calibration curve obtained was linear from 1.0 to 10.0 nmol of kynurenic acid in a 1.0 mL sample solution. The relative standard deviation at 5.0 nmol of kynurenic acid was 5.71% (n = 5). By adjusting the bandwidths for both the excitation and emission to 15 nm, the calibration curve was also linear in the range between 0.1 to 1.0 nmol of kynurenic acid in a 1.0 mL sample solution. This method was applied to the fluorometric determination of trace amounts of kynurenic acid in the control sera.

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“…Plasma and urine kynurenine concentrations were measured by a modification of the method of Joseph & Risby (1975) in which the method was scaled down by 50%; in addition, the perchloric acid/Tiron step was not eliminated from the urinary method as had been suggested. 3-hydroxykynurenine and 3-hydroxyanthranilic acid were measured by the column chromatographic methods of Price, Brown & Yess (1965) as modified by Heeley (1965). Xanthurenic acid was separated by thin layer chromatography as described by Walsh (1965) except that silica gel plates were used.…”

Section: A Nalytical Proceduresmentioning

confidence: 99%

Metabolism of an oral tryptophan load by women and evidence against the induction of tryptophan pyrrolase by oral contraceptives.

Green¹,

Bloomfield²,

Woods³

et al. 1978

Brit J Clinical Pharma

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1A single oral L-tryptophan load (0.245 mol/kg: 50 mg/kg) was given to young women taking no drugs or taking an oral contraceptive. 2 Following tryptophan administration, plasma tryptophan concentrations rose approximately 5 fold reaching a peak 1-2 h after the load. Plasma kynurenine concentrations also rose reaching a peak 3 h after the load. Plasma tryptophan changes were the same in both groups but kynurenine concentrations were lower in the oral contraceptive group 1, 2 and 3 h after the load. 3 There was very little increase in urinary tryptophan or 5-hydroxyindoleacetic acid excretion in the 24 h following the load and just over a doubling of indoleacetic acid excretion. The excretion of these compounds was similar in both groups. 4 The group taking an oral contraceptive excreted less kynurenine in the urine than the control group both during the 24 h before the load and the 24 h following the load, although the percentage increase following the load was much greater in the oral contraceptive group. SIn agreement with previous studies it was found that women on oral contraceptives excreted significantly greater quantities of 3-hydroxykynurenine and xanthurenic acid following the tryptophan load and 3-hydroxyanthranilic acid values also tended to be raised. 6 The volume of distribution, plasma clearance and plasma half-life of tryptophan was similar in both groups of subjects. 7 It is concluded that, in agreement with other studies, the excretion of certain tryptophan metabolites is raised in women on oral contraceptives. However, the data on plasma clearance indicates that, contrary to previous hypotheses this change is not attributable to an increase in the activity of liver tryptophan pyrrolase. Other possible reasons such as a relative deficiency of vitamin B6 are discussed.

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Testing the Functional Capacity of the Tryptophan-Niacin Pathway in Man by Analysis of Urinary Metabolites

Cited by 108 publications

References 195 publications

Circadian periodicity of tryptophan metabolism

Circadian periodicity of tryptophan metabolism

Spectrofluorometric Determination of Kynurenic Acid with Horseradish Peroxidase in the Presence of Hydrogen Peroxide

Metabolism of an oral tryptophan load by women and evidence against the induction of tryptophan pyrrolase by oral contraceptives.

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