EFFECT OF ULTRASOUND ON THE SECRETION OF 5-HYDROXY-3-INDOLEACETIC ACID (5HIAA).
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A densitometric method was developed for the identification and determination of indomethacin and its degradation products, 4-chlorobenzoic acid and 5-methoxy-2-methyl-3-indoleacetic acid, in pharmaceuticals. To separate these compounds, silica gel-coated thin-layer chromatography plates and the following mobile phase were used: 2-propanol-25% ammonia-water (8 + 1 + 1, v/v). UV densitometric measurements were made by comparing the absorption spectra and Rf values of appropriate standards with the pharmaceutical preparations examined. The conditions for separation were established and a low detection limit was obtained. Average recoveries were 100.69, 90.09, and 91.17% for indomethacin, 4-chlorobeznzoic acid, and 5-methoxy-2-methyl-3-indoleacetic acid, respectively.
2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) reduced the uptake of 5-hydroxy-3-indoleacetic acid (5-HIAA) by the choroid plexus in a dose-related manner, while treatment with quinolinic acid at comparable concentrations did not inhibit 5-HIAA uptake. The role of carrier-mediated transport in the clearance of 5-HIAA from cerebrospinal fluid (CSF) was also evaluated in vivo by ventriculocisternal perfusion. Steady-state clearance of 5-HIAA from CSF exceeded that of inulin and was reduced competitively in the presence of 2,4,5-T. However, the clearance was not affected by quinolinic acid. The effect of 2,4,5-T on transport enzyme systems was also studied by electron microscopic cytochemistry. Na+-K+-ATPase and cytochrome oxidase activities in the choroid plexus were reduced by 2,4,5-T. Since this transport system in the choroid plexus is normally responsible for the excretion of the serotonin metabolite from the brain to the plasma, accumulation of endogenously produced organic acids in the CSF and the brain, secondary to reduced clearance by the choroid plexus, could be a contributing factor in the development of neurotoxicity.
Indoleacetic acid was produced from tryptophan by only three of 23 intestinal anaerobes studied. Evidence is presented to show that the formation of indoleacetic acid proceeds through the intermediate, indolepyruvic acid, via transamination with alpha-ketoglutarate rather than by tryptamine pathway.
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The metabolism of tryptophan by Taphrina deformans has been studied to confirm the reported ability of this organism to produce tryptamine. Such amine production was not observed, despite use of amine oxidase inhibitors at levels which should have resulted in the accumulation of tryptamine in the medium. It has been shown that the metabolites of tryptophan include indolepyruvic acid, indolelactic acid, tryptophol, and indoleacetic acid, and that the original report of tryptamine production must be reevaluated in light of the extraction procedures employed.
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Indoleacetic acid (IAA) is produced in cancer tissue and promotes the growth of cancer cells and of the surrounding cells which become cancerous. It was shown that the urine of cancer patients contains larger amounts of IAA than that of healthy persons (except diabetics). This increased IAA level may be derived from the cancer tissue. The measurement of urinary IAA can thus be used to screen cancer patients. Various assay methods for IAA were tested, but 15 min. are required even with the modified HPLC used in this laboratory directly with unpurified urine. Hence it is unsuitable for measuring large numbers of samples within short period. The present work reports on a simple, easy and rapid method for determining urinary IAA in large numbers of samples by using Avena coleoptile sections. Ten sections are floated for 3 hr. on 1/50 diluted urine with 0.5 ppm gibberellic acid (GA). Up to a certain limit their elongation is proportional to the IAA concentration in the diluted urine. Persons whose urine causes coleptile section to elongate more than 1.3 mm require detailed clinical examination to determine whether or not they suffer from cancer.
The oxidative decarboxylation of L-tryptophan to yield 3-indoleacetamide, catalyzed by tryptophan 2-monooxygenase, represents a controlling reaction in the synthesis of indoleacetic acid by Pseudomonas savastanoi (Pseudomonas syringae pv. savastanoi), a gall-forming pathogen of olive (Olea europea L.) and oleander (Nerium oleander L.). Production of indoleacetic acid is essential for virulence of the bacterium in its hosts. Tryptophan 2-monooxygenase was characterized to determine its role in indoleacetic acid metabolism in the bacterium. The enzyme was purified to apparent homogeneity from Escherichia coli cells containing the genetic locus for this enzyme obtained from P. savastanoi. The preparation contained a single polypeptide with a mass of 62,000 that cross-reacted immunologically with a homologous protein in P. savastanoi. The holoenzyme contained one FAD moiety/subunit with properties consistent with a catalytic function. The enzyme preparation catalyzed an L-tryptophan-dependent O2 uptake and yielded 3-indoleacetamide as a product. Enzyme activity fit simple Michaelis Menten kinetics with a Km for L-tryptophan of 50 microM. 3-Indoleacetamide and 3-indoleacetic acid were identified as regulatory effectors. The apparent Ki for 3-indoleacetamide was 7 microM; that for indoleacetic acid was 225 microM. At Km concentrations of tryptophan, enzyme activity was inhibited 50% by 25 microM 3-indoleacetamide. In contrast, 230 microM indoleacetic acid was required to effect a similar inhibition. Phenylalanine and tyrosine were ineffective as regulatory metabolites. These results indicate that IAA synthesis in P. savastanoi is regulated by limiting tryptophan and by feedback inhibition from indoleacetamide and indoleacetic acid.
When DL-tryptophan-2-C(14) was incubated with washed cells or cell-free preparations of Pseudomonas savastanoi, two radioactive metabolites were formed. One was identified as indoleacetamide and the second, indoleacetic acid. The amount of indoleacetamide in the reaction mixture increased rapidly during the early stages of incubation; it reached a peak after 15 minutes and declined steadily there-after. Indoleacetic acid, on the other hand, accumulated slowly throughout the incubation period. Cell-free preparations preferentially utilize the L-isomer of tryptophan for the synthesis of indoleacetamide and indoleacetic acid. The results of these experiments suggest, therefore, that P. savastanoi synthesizes indoleacetic acid by the following reactions: L-tryptophan--> indoleacetamide-->indoleacetic acid.