Tryptophan metabolites in urine

Auricchio et al. (A9-A11) analyzed the excretory pattern of tryptophan metabolites in urine of 10 normal newborn children from the first to 30th day of life. During the period 1st day to 4th-llth day no tryptophan metabolites were detected. During a second phase, 5th-12th day until 7th-28th day, several metabolites together with their conjugates were... 

The estrogenic components of OCAs have been linked to these effects. Estrogens given alone produce the same changes in urinary tryptophan metabolites of women as do estrogen-progestogen combinations (B20, P8, R7), An adult male treated with ethynylestradiol (0.1 mg daily) had abnormal levels of tryptophan metabolites in urine, which returned promptly to normal when treatment was stopped (R7). Progestogens, in contrast, have been found not to produce these effects (R9, RIO). 

Means of assessing vitamin Be status other than measuring tryptophan metabolites in urine include the estimation of vitamin Bo compounds... 

There is a rapid decrease in urinary vitamin Bg when normal subjects are placed on a diet low in Be content (K3). Recently Miller et(d. M14) reported a study of five women receiving a constant diet of known Bo content. Three subjects taking OCAs showed most of the expected changes in tryptophan metabolites in urine and some evidence for decreased urinary excretion of Bo. This was in contrast to the earlier findings by Aly et al. (A5) that Be excretion in urine was unchanged by OCAs, and could have been due to a number of factors including differences in the organisms used to assay urine Bo. Urinary 4-pyridoxic add output in urine is also decreased quickly on a Ba-deficient diet, and has been reported to be normal in OCA-users (P8). 

These assessments of Bg nutrition in OCA-users by methods odier than studying tryptophan metabolism do indicate that at least some of the women who excrete abnormal quantities of tryptophan metabolites in urine have a degree of true deficiency in vitamin Bg. However, the possibility that contraceptive steroids may affect binding of B compounds to blood proteins, or to proteins in erythrocyte proteins remains to be explored. 

Analysis of nicotinic acid, nicotinamide, and its metabolites in biological materials, i.e., blood, plasma, urine, and tissues, is important in studies on biochemical pathways (Hengen and deVries, 1985). Finder et al. (1971) described several paper and thin-layer chromatographic systems useful for the differentiation of nucleotides in tissues derived from nicotinamide and nicotinic acid. Hengen and deVries (1985) provided a table summarizing the Rp values of nicotinic acid, nicotinamide, and various intermediates of NAD+ and NADP-I- synthesis for both paper and thin-layer chromatography. Haworth and Walmsley (1972) used two-dimensional TLC on silica gel for the identification of tryptophan metabolites in urine and resolved 32 compounds including nicotinic acid and nicotinamide. Kala et al. (1978) used silica gel TLC to examine urine for nicotinic acid and its metabolites after administration of nicotinyl alcohol. They... 

V3. Vassella, F., and Hellstrom, B., On the excretion of tryptophan metabolites in human fetal and neonatal urine. Biol. Neonatorum 4, 102-112 (1962). 

Another area of clinical interest which has benefited from the use of BCD is the study of tryptophan metabolism. Tryptophan is an essential amino acid which can be metabolized in a number of ways as illustrated in Figure 3. One of the minor pathways leads to the synthesis of the neurotransmitter 5-hydroxytryptamine (5HT), abnormal brain levels of which have been associated with a number of diseases including Down s syndrome[15] and depression [lb] As part of a study into the biochemistry of depressive illnesses, I investigated methods for the determination of tryptophan metabolites in blood and urine. HPLC proved to be a useful technique for separating these compounds, so the possibility of using BCD was examined [17]. 

Botanists have been interested in the plant hormone heteroauxin which is indoleacetic acid. It occurs in the urine and has been shown to be a tryptophan metabolite in plants (see 7J). Another focus of general biological interest of tryptophan is that it is the precursor of the brown eye pigments of insects, ommochrome (875). 

Plasma and urine samples from atherosclerotic and control rats were comparatively analyzed by ultrafast liquid chromatography coupled with ion trap-time-of-flight (IT-TOF) MS (UFLC-IT/TOF-MS) (16). They identified 12 metabolites in rat plasma and 8 metabolites in rat urine as potential biomarkers. Concentrations of leucine, phenylalanine, tryptophan, acetylcar-nitine, butyrylcamitine, propionylcamitine, and spermine in plasma and 3-0-methyl-dopa, ethyl /V2-acety I -1. -argininate, leucylproline, glucuronate, A(6)-(A-threonylcarbonyl)-adenosine, and methyl-hippuric acid in urine were decreased in atherosclerosis rats ursodeoxycholic acid, chenodeoxycholic acid, LPC (06 0), LPC (08 0), and LPC (08 1) in plasma and hippuric acid in urine were increased in atherosclerosis rats. The altered metabolites demonstrated abnormal metabolism of phenylalanine, tryptophan, bile acids, and amino acids. Lysophosphatidylcholine (LPC) plays an important role in inflammation and cell proliferation, which shows a relationship between LPC in the progress of atherosclerosis and other inflammatory diseases. 

As previously mentioned, 3-hydroxyanthranilic acid was found chro-matographically by Musajo et al. (M18) in the urine of tuberculous patients. This was the starting point for an extensive investigation of tryptophan metabolites excreted spontaneously, i.e., by normal subjects or patients with different diseases all fed a normal diet without added tryptophan. 

The amounts of the two substances originally present in the urine were higher than those actually isolated. It must be emphasized, however, that tryptophan metabolites have rarely been extracted from urine when neither special diets nor supplementary tryptophan are used. Furthermore, urine of hemoblastotic patients can be considered, together with Calliphora erythrocephala pupae, as one of the rare natural sources of 3-hydroxykynurenine. 

Price (Pll) found that when human subjects with no known disease were given 2-4 or 8 g L-tryptophan in a single dose, the increased urinary excretion of the metabolites was not strictly proportional to the amount of amino acid ingested. Thus, when 2 g L-tryptophan was administered, about 1.8% of the amino acid could be recovered in urine in the form of increased excretion of the metabolites. When the dose was 4 or 8 g, 2.7 or 6.8% respectively, could be recovered. These figures are in good agreement with those obtained by us with a different method. 

Urine from 8 schizophrenic patients and 9 normal controls were analyzed (B21) for metabolites of tryptophan, before and after oral doses of this compound (80 mg/kg). The urinary output of tryptophan metabolites was found by these authors (B21) to be higher in controls than in the patients. 

Chizhova and Ivanova (C7) studied 20 children, aged 1-12 years, under therapy for leukemia and 10 healthy children as control. A total of 15-20 g of tryptophan was administered during 5-10 days (1.5-3 g/day) to 7 children whereas 13 were given a single dose of 2-3 g. Daily determinations of urinary metabolites by paper chromatography demonstrated a disturbance of tryptophan metabolism in 19 of the 20 leukemic children before and after tryptophan loading. Kynurenine, 3-hydroxykynurenine, and anthranilic and 3-hydroxyanthranilic acids appeared in urine, whereas 5-hydroxyindoleacetic acid was absent in the majority of the young patients. The disturbances of tryptophan metabolism were similar in all of them. Administration of vitamin Be restored tryptophan metabolism to normal in the majority of the patients. 

T3. Tompsett, S. L., The determination in urine of some metabolites of tryptophan-kynurenine, anthraniUc acid and 3-hydroxyanthranilic acid—and reference to the presence of o-aminophenol in urine. CZin. Chim. Acta 4, 411-419 (1959). 

As with the other B vitamins that act as coenzymes biochemical assessment of vitamin Bg can, be made by direct chemical analysis of the vitamer or its metabolites, or by functional means. Measurements that have been used are PLP in plasma or red cells, its metabolite 4 PA in urine or plasma, the activity and activation coefficient of the red cell aminotransferases (aspartate and alanine), and the tryptophan load metabolite excretion test. As no single marker adequately reflects status, a combination of these markers olfers the best approach. 

Abnormal indole derivatives in the urine and low levels of serotonin (a product of tryptophan metabolism) in blood and brain point to a defect in tryptophan metabolism in PKU. 5-Hydroxytryptophan decarboxylase, which catalyzes the conversion of 5-hydroxytryptophan to serotonin, is inhibited in vitro by some of the metabolites of phenylalanine. Phenylalanine hydroxylase is similar to the enzyme that catalyzes the hydroxylation of tryptophan to 5-hydroxytryptophan, a precursor of serotonin. In vitro, phenylalanine is also found to inhibit the hydroxylation of tryptophan. The mental defects associated with PKU may be caused by decreased production of serotonin. High phenylalanine levels may disturb the transport of amino... 

Our knowledge of tryptophan began some 100 years ago. In 1901 Hopkins and Cole1 isolated tryptophan from a pancreatic digest of casein. Its structure was established in 1907 by Ellinger and Flamand,2 who synthesized a substance that was identical to the tryptophan isolated by Hopkins and Cole. It is noteworthy that about 50 years prior to the discovery of tryptophan by Hopkins and Cole,1 aspects of tryptophan metabolism began to appear in the research literature, when in 1853 Liebig discovered kynurenic acid in dog urine.3 Subsequently, kynurenine, a tryptophan metabolite, was identified,4 5 and the relationship of kynurenic acid to tryptophan was understood. A brief review on the discovery of tryptophan has been described by Curzon.6... 

The presence of another contaminant peak in L-tryptophan implicated in EMS was detected upon HPLC with both UV and FL analyses by Toyo oka et al.9 and was characterized as PAA by Goda et al.7 Adachi et al.15 studied the metabolism of PAA in rats and described four metabolites of PAA in the urine (N-(hydroxyphenyl)glycine, N-phenylglycine, 3-(phenylamino)lactic acid, and 3-(hydroxy-phenylamino)-lactic acid). The results suggested that the degradation pathway of PAA was similar to that of phenylalanine. Other studies with PAA are described in Section 11.10. 

Xanthurenic acid was the first tryptophan metabolite found to be elevated in the urine of pyridoxine-deficient animals (L5). When vitamin Be is deficient, liver kynureninase (Fig. 1) which is located in the cytosol, becomes rapidly depleted of PLP. However, the transaminases that metabolize kynurenine and 3-hydroxykynurenine to kynurenic acid and xanthiuenic acid, respectively, are located in both kidney and liver and... 

Rose [305] reported the excretion of grossly increased amounts of xanthurenic acid in the urine of women taking combination products. A similar increase in tryptophan metabolites occurs in pregnancy and has been interpreted as indicating pyridoxine deficiency [306]. Dewhurst [307] subsequently postulated a causal connection between dysfunction of trytophan metabolism and certain types of depression. Winston [308] developed the concept further by suggesting that depression from oral contraceptive medication be treated with pyridoxine. Price and Toseland [309] have proposed routine inclusion of pyridoxine in oral contraceptive preparations. Developments will be awaited with interest. 

Chemiluminescence resulting from the nonenzymatic degradation of the tryptophan metabolite 3-HOA (and believed to reflect degradation from Compound I to Compound IV as shown in Chart 2) is significantly increased in the urine of bladder cancer patients and in the urine of heavy tobacco smokers (285, 286). The administration of ascorbate (1 to 2 g p.o. per day) results in a significant decrease in chemiluminescence and completely prevents the formation of Compound IV even in voided urine to which 3-HOA has then been added (286). 

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