PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “indole”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1976

The binding of indole to the alpha-subunit and beta2-subunit and to the alpha2beta2-complex of tryptophan synthase from Escherichia coli. Identification of a second indole-binding site on the alpha-subunit.

The binding of indole and indolepropanol phosphate, an analogue of the substrate indoleglycerol phosphate, to the individual alpha and beta2-subunits and to the alpha2beta2-complex of tryptophan synthase was studied by equilibrium dialysis. The use of [14C]indole and indolepropanol [32P]phosphate permitted simultaneous binding studies to be carried out. Competition between indole and indolepropanol phosphate in binding to a particular site was taken as evidence for that site being part of the active site of the alpha-subunit. The binding of indole to the active site of the alpha-subunit is weak (Kd = 18mM). A second distinct site binds indole more strongly (Kd = 1.5 mM) and interacts with the active site indirectly. It is therefore designated an effector site. Furthermore, the binding of indole and/or indolepropanol phosphate appears to stabilize different conformations of the alpha-subunit. The beta2-subunit binds indole only weakly (Kd = 12 mM) to many (n = 10) sites per polypeptide chain. The alpha2beta2-complex retains one or two sites per alphabeta-equivalent of relatively high affinity (Kd = 1.2 mM). The active sites of the component alpha and beta-subunits probably belong to the second class of many (n = 40) sites of low (Kd = 30 mM) affinity for indole. These findings support conclusions from the literature that both bi-substrate reactions involving indole catalyzed by tryptophan synthase and its subunits must follow strictly ordered addition mechanisms with the respective other substrate adding first.

Binding Sites↗
PubMed1978

Diarylamidine derivatives with one or both of the aryl moieties consisting of an indole or indole-like ring. Inhibitors of arginine-specific esteroproteases.

A series of 62 diarylamidine derivatives was evaluated for their antiproteolytic activity. In all but two of the compounds one or both of the amidino-substituted aryl moieties was either an indole or an indole-like ring. The latter included indene, benzimidazole, benzofuran, benzol[beta]thiophene, and several other related nitrogen-containing heterocycles. Several of the compounds exhibited considerable inhibitory potency against thrombin, trypsin, and pancreatic kallikrein. An outstanding inhibitor of trypsin was found in bis(5-amidino-2-benzimidazolyl)methane (compound 42) with a Ki value of 1.7 X 10(-8) M(pH. 8.1, 37 degrees C). Another derivative, 1,2-di(4-amidino-2-benzofuranyl)ethane (compound 21), proved to be a highly effective inhibitor of the overall blood clotting process. From a general structure-activity standpoint these compounds demonstrate that minor structural variations of low-molecular-weight inhibitors can result in significant changes in specificity and potency with regard to antiproteolytic activity.

Amidines↗
PubMed1977

Yersinia enterocolitica, indole-negative and indole-positive biotypes. Isolation, identification and sensitivity to chemotherapeutics.

A population of 200 Y. enterocolitica strains of the serotype 03 and 100 strains belonging to other serotypes mostly, however, to the biotype 1 were examined for their sensitivity to chemotherapeutics. The serotype 03 strains were obtained from human material of diarrhoeal cases, the origin of other serotypes was various. They originated from human extraintestinal material, animals, water and foods. To summarize their results, the authors elaborated an antibiogram presented in graphs.

Anti-Bacterial Agents↗
PubMed1978

Differential susceptibility of indole-positive and -negative strains of Klebsiella pneumoniae to cefazolin, choramphenicol and tetracycline.

Biochemical properties and antibiotic susceptibilities of 168 clinical isolates of Klebsiella pneumoniae were tested. On the basis of the indole reaction, 30 isolates (18%) were indole-positive and 138 isolates (82%) were indole-negative. A significant difference in antibiotic susceptibility was found in each of the two groups of isolates. Of the indole-negative isolates, 82.6% were susceptible to cefazolin at 6.25 microgram/ml or lower, while the indole-positive isolates varied in susceptibility to cefazolin. All of the indole-positive isolates were susceptible to chloramphenicol and tetracycline, but the indole-negative isolates varied in their susceptibility to these antibiotics. Whereas there was no relationship between indole production and susceptibility to cephalothin among the K. pneumoniae isolates studied, it appeared that there was a correlation between the indole reaction and susceptibility to cefazolin, chloramphenicol and tetracycline.

Cefazolin↗
PubMed1978

Inhibition of polycyclic aromatic hydrocarbon-induced neoplasia by naturally occurring indoles.

Indole-3-carbinol, 3,3'-diindolylmethane, and indole-3-acetonitrile, three indoles occurring in edible cruciferous vegetables, have been studied for their effects on 7,12-dimethylbenz(a)anthracene-induced mammary tumor formation in female Sprague-Dawley rats and on benzo(a)pyrene-induced neoplasia of the forestomach in female ICR/Ha mice. When given by p.o. intubation 20 hr prior to 7,12-dimethylbenz(a)anthracene administration, indole-3-carbinol and 3,3'-diindolylmethane had an inhibitory effect on mammary tumor formation, but indole-3-acetonitrile was inactive. Indole-3-carbinol when added to the diet for 8 days prior to challenge with 7,12-dimethylbenz(a)anthracene inhibited mammary tumor formation, whereas indole-3-acetonitrile did not. Dietary administration of all three indoles inhibited benzo(a)pyrene-induced neoplasia of the forestomach in ICR/Ha mice. The identification of dietary constituents that can inhibit chemical carcinogens ultimately may be of value in understanding the balance of factors that determines the neoplastic response to these cancer-producing agents in the environment.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2026

Unraveling anaerobic indole degradation in an acclimated sludge consortium: Candidate pathways and microbial division of labor inferred from metagenomic and metatranscriptomic analyses.

Indole is a widespread nitrogen-containing heterocyclic compound in manure, sludge, and wastewater systems, yet the enzymes and microbial populations involved in its anaerobic transformation remain poorly resolved. Here, we established a long-term acclimated anaerobic sludge consortium and combined degradation assays, metabolite profiling, metatranscriptomics, and genome-resolved metagenomics to investigate the functional basis of anaerobic indole degradation. After 120 days of acclimation, the consortium stably degraded 100 mg/L indole, whereas skatole was not effectively removed under the same strategy, indicating substrate-specific adaptation of the microbial community. Metabolite profiling detected oxindole, dioxindole, isatin, and anthranilic acid, supporting a putative transformation route involving pyrrole-ring oxidation and ring cleavage toward anthranilate-like intermediates. Metatranscriptomic analysis identified 16,660 differentially expressed genes after indole addition, with strong transcriptional responses involving oxidoreductases, hydrolases, cofactor-dependent redox metabolism, aromatic-CoA-related metabolism, and methane metabolism-associated pathways. Transcriptional responses highlighted the xanthine dehydrogenase-like molybdenum-enzyme system and isatin hydrolase as candidate contributors to upstream indole transformation, whereas those of abmG-like, bcrC, and oah genes were consistent with possible anthranilic acid activation and downstream CoA-type processing. MAG-resolved analysis further suggested that these candidate functions may be distributed among populations affiliated with Bacteroidota, Chloroflexota, Desulfobacterota, and Methanobacterium. Together, these findings establish a stable anaerobic indole-degrading consortium and provide a testable functional framework for syntrophic interactions linking upstream indole transformation, aromatic-CoA metabolism, and methanogenesis-associated carbon flow.

Anaerobic degradation↗
PubMed1979

Peroxide oxidation of indole to oxindole by chloroperoxidase catalysis.

In the presence of chloroperoxidase, indole was oxidized by H2O2 to give oxindole as the major product. Under most conditions oxindole was the only product formed, and under optimal conditions the conversion was quantitative. This reaction displayed maximal activity at pH 4.6, although appreciable activity was observed throughout the entire pH range investigated, namely pH 2.5-6.0. Enzyme saturation by indole could not be demonstrated, up to the limit of indole solubility in the buffer. The oxidation kinetics were first-order with respect to indole up to 8 mM, which was the highest concentration of indole that could be investigated. On the other hand, 2-methylindole was not affected by H2O2 and chloroperoxidase, but was a strong inhibitor of indole oxidation. The isomer 1-methylindole was a poor substrate for chloroperoxidase oxidation, and a weak inhibitor of indole oxidation. These results suggest the possibility that chloroperoxidase oxidation of the carbon atom adjacent to the nitrogen atom in part results from hydrogen-bonding of the substrate N-H group to the enzyme active site.

Catalysis↗
PubMed1978

Excitation of indole-3-acetic acid (an auxin) in a linoleate-lipoxygenase system.

The weak luminescence that accompanies the linoleate-lipoxygenase reaction was greatly enhanced by the addition of indole analogues, and especially indole acetic acid. The main emitting species in the indole acetic acid-linoleate-lipoxygenase system was analysed spectrophotometrically in the visible region and ascribed to the transition of excited indole acetate in triplet state to its ground state. Such an excited indole acetate could be generated by transfer of energy from the excited CO2 and excited carbonyl (generated by the linoleate-lipoxygenase reaction) to indole acetate in the ground state, but not by cleavage of the dioxetane analog (positions 2 and 3 on the indole ring).

Deuterium↗
PubMed1977

The van urk-Salkowski reagent--a sensitive and specific chromogenic reagent for silica gel thin-layer chromatographic detection and identification of indole derivatives.

The chromogenic reagent described has been tested with seventy-nine indole derivatives and found to be very sensitive and indole-specific. The lower limit of detection on silica gel thin-layer plates was between 25 and 50 ng for most indoles. Phenols and hydroxy-, and amino-benzoic acids, hydroxy-, and methoxy-cinnamic acids did not yield chromophores with the exception of p-amino-benzoic acid and p-hydroxy-cinnamic acid which gave yellow and pink chromophores at concentrations greater than 1 and 2 mug. Although many of the C-3 substituted indoles such as indole-3-acetic acid and tryptamine had colors in the reddish-violet-blue color region, most exhibited sufficient color differentiation to allow their identification by thin-layer chromatography. The procedure was simple and required only 10 min from the time of spraying the thin-layer plate until full color development was reached. The colors had a wide spectral range from yellow of the indole-3-glyoxylamide chromophore to blue of the melatonin chromophore, and were extremely stable.

Benzaldehydes↗
PubMed1978

Flash photolysis of human serum albumin: characterization of the indole triplet absorption spectrum and decay at ambient temperature.

The method of flash photolysis was used to identify the transient absorption spectrum and to characterize the decay kinetics of the indole triplet of human serum albumin. This protein was studied because it contains a single indole side chain which is deeply buried in an expandable oily region and because the phosphorescence of the homologous indole in bovine serum albumin could not be detected at ambient temperatures. The transient was identified on the following basis: (i) its triplet-triplet absorption spectrum was similar to those previously reported for indole and tryptophan; (ii) it was quenched by small quantities of oxygen; and (iii) it was photobleached by 370- to 700-nm light. In a nitrogen-saturated solution at room temperature, the indole triplet decays exponentially for more than a factor of 10 with a lifetime of 0.5 msec. These observations suggest that, because of its exponential decay and relatively long lifetime, the triplet will be more valuable than the indole singlet as an intrinsic reporter group for the study of the structure and dynamics of proteins in solution.

Humans↗
PubMed1977

A study of antidepressant activity of some indole alkylamines.

The antidepressant characteristics of three indole alkylamines were investigated and compared with phenelzine and imipramine by utilising specific pharmacological tools like reserpine, amphetamine, tryptamine and tetrabenazine for determining their possible mechanism of action. Amongst the three indole compounds investigated, indole-3-(2-aminopropyl)-acetate (U-14 164E), indole-3(2-aminobutyl)-d-acetate (u-17 312E) and beta-phenethylhydrazine (phenelzine) produced complete antagonism to reserpine induced sedation, hypothermia as well as facilitation of convulsive seizures. Some of these features suggest that MAO inhibition might be a common mechanism of action of these indoles. The potentiation of CNS effects of tryptamine by these compounds is an outstanding feature of MAO inhibitors, while imipramine is ineffective. Qualitative differences between these indoles and imipramine are evident in the tetrabenazine test. The potentiation of amphetamine induced motor excitation and pentobarbitone narcosis has been explained.

Analgesia↗