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PubMed1991

In-vitro testing and the carcinogenic potential of several nitrosated indole compounds.

4-chloro-methoxyindole is a naturally occurring compound in Vicia faba which can easily react with nitrite to form a N-nitroso compound. In this in vitro study, the potential genotoxic effects of nitrosated 4-chloro-6-methoxyindole and its structural analogue 4-chloroindole were evaluated for the first time by using both Salmonella and Chinese hamster V79 cells. Additionally, the inhibition of gap junctional intercellular communication in V79 cells by these compounds was determined; this is a validated parameter for tumor-promoting activity. Most assays were also performed with nitrosated indole-3-acetonitrile, a naturally occurring compound in brassicas. Both nitrosated chloroindoles were highly mutagenic to Salmonella typhimurium TA100 without the need of exogenous metabolic activation and were potent inducers of Sister Chromatid Exchanges. Nitrosated indole-3-acetonitrile generated the same effects, although at much higher concentrations. Equivocal results were obtained for the nitrosated chloroindoles in a forward mutation assay using the hypoxanthine guaninephosphoribosyltransferase locus. All nitrosated indole compounds significantly inhibited gap junctional intercellular communication. These results indicate that nitrosated chloroindoles and nitrosated indole-3-acetonitrile should be considered as mutagens and agents with potential tumor-promoting capacity.

Animals↗
PubMed1983

Indole metabolism in the pineal organ of the pigeon with special reference to melatonin-synthesizing cells. In vitro study combining thin layer chromatography, autoradiography and pharmacological treatment.

By means of radioimmunoassay a clear-cut peak of melatonin concentration was found in the pineal organ of the pigeon at the middle of the scotophase (Coisin et al. 1982a). The aim of the present study was to identify the cell type responsible for the nocturnal indole metabolism, including melatonin synthesis, in the pineal of this avian species. After a short-term incubation or organ culture in the presence of [3H]-indolic precursors, [3H]-5-hydroxytryptophan or [3H]-5-hydroxytryptamine, the relative amounts of deaminated and acetylated products occurring in the pineal organ were measured by the use of thin layer chromatography and liquid-scintillation counting. It was possible to modify the relative amounts of deaminated and acetylated indoles by the application of some inhibitors of monoamine oxidase and cyclic nucleotide phosphodiesterase. Irrespective of the experimental conditions, high-resolution autoradiography combined with the above-mentioned radiochemical experiments showed that the cells of the receptor line (modified photoreceptor cells) are responsible for indole storage and metabolism, and very probably also for melatonin biosynthesis. The other cell types of the pineal parenchyma did not display significant labeling.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1995

Effects of pineal indoles on ovarian response to gonadotropin-induced ovulation in mice.

Ovulation was induced in immature mice by injections of pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) spaced 48 hours apart. The mice were divided into six groups: one group received intraperitoneal injections of normal saline, another group received alcoholic saline which was used as the vehicle of pineal indoles, and the remaining groups received respectively hydroxyindoleacetic acid (HIAA), melatonin (MEL), methoxytryptamine (MTA) and methoxytryptophol (MTP). The pineal indoles were administered 24 hours before, on the same day as, 24 hours after and 48 hours after the PMSG injection. The mice were sacrificed 24 hours after the HCG injection. The numbers of growing primary follicles, multilaminar primary follicles, Graafian follicles, preovulatory follicles and corpora lutea in the ovary were not altered by treatment with pineal indoles. However, there was an increased incidence of follicular atresia in the groups treated with MEL, MTA and MTP. The pineal indoles did not affect the number of ovulated oocytes, but there was a large number of degenerated and fragmented ovulated oocytes in the MTA- and MTP-treated groups. Treatment with MEL, MTA and MTP also resulted in lower plasma levels of estradiol-17 beta and progesterone.

5-Methoxytryptamine↗
PubMed1994

Development of pre-implantation mouse embryos under the influence of pineal indoles.

The developmental toxicity of pineal hormones on mouse embryos was examined both in vitro and in vivo. Pregnant ICR mice were divided into groups which received at 1.5 days post-coitum (p.c.) and again at 2.5 days p.c. a subcutaneous injection of one of the following pineal indoles: hydroxyindoleacetic acid (HIAA), melatonin (MEL), methoxytryptophol (MTP) or methoxytryptamine (MTA). Mice treated with the injection vehicle served as the control. The animals were sacrificed at 17.5 days p.c. The pineal indole treatment did not cause changes in the gravid uterine weight, numbers of implants, early resorption, late resorption, dead fetuses and live fetuses, fetal weight or fetal crown-rump length, and did not produce embryos with external or visceral defects. However, some mice treated with MTP or MTA produced litters in which all embryos underwent resorption. Cultured embryos at the 4-cell stage were treated with the aforementioned pineal indoles and examined after 24, 48, 72 and 96 hours. It was found that MTA retarded embryonic development at all time points studied. HIAA also produced a slight inhibitory effect on embryonic development. Some embryos underwent degeneration in response to the MTA and HIAA treatments. However, MEL- and MTP-treated embryos were in general developmentally similar to control embryos. When cultured embryos were treated at the 8-cell to compacting stage, it was found that MTA exerted only a slight retarding effect on embryonic development, while other indoles were devoid of any conspicuous effects.

5-Methoxytryptamine↗
PubMed2006

Brominated indoles and phenols in marine sediment and water extracts from the north and baltic seas-concentrations and effects.

This work presents results from analytical as well as ecotoxicologic investigations of sediment and water samples from the North and Baltic Seas. A bioassay-directed procedure was used to investigate cause-effect relationships between observed effects in acute laboratory bioassays (luminescent bacteria assay with Vibrio fischeri and embryo test with Danio rerio) and analyte concentrations in extracted samples. Brominated phenols and indoles-including 4-bromophenol; 2,4-dibromophenol; 4- and 6-bromoindole; 3,4-, 4,6-, and 3,6-dibromoindole; and tribrominated compounds-were identified in partly remarkable concentrations (up to 40,000 ng g(-1) total organic carbon TOC for 4-bromophenol) in North Sea sediment samples and water samples (913 ng L(-1) 3,6-dibromoindole) from the German Bight. The toxicity of some of the identified brominated substances was low, with median effect concentration levels (EC(50)) ranging from 0.08 to 21.7 mg/L for V. fischeri and 4.3 to 46.3 mg/L for D. rerio. Comparison of the concentrations of analytes with ECs showed a toxicity contribution of brominated phenols and indoles to overall toxicity of the fraction. In the case of one water sample from the German Bight, brominated phenols and indoles accounted for the observed toxicity. Brominated phenols and indoles, which are assumed to be of biogenic origin, have rarely been discussed so far in the context of ecotoxicologic effects in marine ecosystems.

Aliivibrio fischeri↗
PubMed2002

Isolation of an Acinetobacter sp. ST-550 which produces a high level of indigo in a water-organic solvent two-phase system containing high levels of indole.

Acinetobacter sp. strain ST-550 was isolated from fumus soil as an efficient indigo producer in the presence of organic solvent. The minimum inhibitory concentration of indole was 0.4 mg/ml for ST-550. ST-550 produced only a small amount of indigo (less than 0.01 microg/ml) when grown in the presence of indole at concentrations of 0.05 to 0.3 mg/ml without any organic solvent. However. ST-550 produced indigo effectively when grown in the presence of a large volume of diphenylmethane and a high level of indole: optimized conditions were 3 ml of a medium containing 0.3 ml diphenylmethane and 2.7 mg indole. Under these conditions, ST-550 produced 0.88 mg indigo (292 microg/mI medium).

Acinetobacter↗
PubMed2002

Occurrence and formation of indole-3-acetamide in Arabidopsis thaliana.

An HPLC/GC-MS/MS technique (high-pressure liquid chromatography in combination with gas chromatography-tandem mass spectrometry) has been worked out to analyze indole-3-acetamide (IAM) with very high sensitivity, using isotopically labelled IAM as an internal standard. Using this technique, the occurrence of IAM in sterile-grown Arabidopsis thaliana (L.) Heynh. was demonstrated unequivocally. In comparison, plants grown under non-sterile conditions in soil in a greenhouse showed approximately 50% higher average levels of IAM, but the differences were not statistically significant. Thus, microbial contributions to the IAM extracted from the tissue are likely to be minor. Levels of IAM in sterile-grown seedlings were highest in imbibed seeds and then sharply declined during the first 24 h of germination and further during early seedling development to remain below 20-30 pmol g(-1) fresh weight throughout the rosette stage. The decline in indole-3-aetic acid (IAA) levels during germination was paralleled by a similar decline in IAM levels. Recombinant nitrilase isoforms 1, 2 and 3, known to synthesize IAA from indole-3-acetonitrile, were shown to produce significant amounts of IAM in vitro as a second end product of the reaction besides IAA. NIT2 was earlier shown to be highly expressed in developing and in mature A. thaliana embryos, and NIT3 is the dominantly active gene in the hypocotyl and the cotyledons of young, germinating seedlings. Collectively, these data suggest that the elevated levels of IAM in seeds and germinating seedlings result from nitrilase action on indole-3-acetonitrile, a metabolite produced in the plants presumably from glucobrassicin turnover.

Aminohydrolases↗
PubMed1984

Inhibition of indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase by beta-carboline and indole derivatives.

beta-Carboline derivatives inhibited both indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase activities from various sources. Among them, norharman is most potent for both enzymes from mammalian sources. Kinetic studies revealed that norharman is uncompetitive (Ki = 0.12 mM) with L-tryptophan for rabbit intestinal indoleamine 2,3-dioxygenase, and linearly competitive (Ki = 0.29 mM) with L-tryptophan for mouse liver tryptophan 2,3-dioxygenase. In addition, some beta-carbolines selectively inhibited one enzyme or the other. Pseudomonad tryptophan 2,3-dioxygenase was inhibited by a different spectrum of beta-carbolines. Such a selective inhibition by the structure of substrate analogs is more evident by the use of indole derivatives. Indole-3-acetamide, indole-3-acetonitrile and indole-3-acrylic acid exhibited a potent inhibition for mammalian tryptophan 2,3-dioxygenase, while they moderately inhibited the pseudomonad enzyme. However, they showed no inhibition for indoleamine 2,3-dioxygenase. These results suggest the difference of the structures of the active sites among these enzymes from various sources.

Animals↗
PubMed1980

X-ray structural and conformational studies of [5'-(tryptaminocarbonyl)-2'-deoxyribofuranosyl]thymine, a model compound for the study of the interaction between indole and thymine rings.

The crystal structure of [5'-(tryptaminocarbonyl)-2'-deoxyribofuranosyl]-thymine was determined by an X-ray method in order to elucidate a fundamental feature of interaction between indole and thymine rings. Refinement resulted in a conventional R value of 0.043. The bond lengths and angles are in good agreement with those of the related compounds. The deoxyribose unit has a C2'-endo envelope conformation, and orientation of the thymine base with respect to the sugar is anti. In the crystal, the double layers of the thymidine moieties are formed by the hydrogen bonds around a two-fold screw axis and a single layer of the indole moieties is held together by van der Waals contact, and they are alternately packed parallel to the bc-plane. The conformation of the molecule is an extended form, and the intra- and intermolecular interactions between the indole and thymine rings are not observed in the crystal because the dihedral angle of both rings is approximately a right angle (95.8 degrees), and there is no hydrogen bond or short contact between these rings. It was, however, suggested from the ultraviolet spectroscopic study in dilute solution and from the conformational analysis by energy calculation that the most stable conformation is a folded form with the intramolecular stacking interaction between indole and thymine rings. Therefore, the extended form observed in the crystal might be caused by the packing interaction between the neighboring molecules.

Chemical Phenomena↗
PubMed1983

Stacking interaction of indole ring with thiazolium ring and effect for H-D exchange reaction of thiamin.

As part of a program to clarify the possible binding mode of tryptophan with thiamin coenzyme, the interaction between the indole and thiazolium rings has been studied by using a model compound, 2-(3,4-dimethylthiazolium-5-)ethyl indole-3-propionate, and the prominent stacking formation between both rings has been evidenced by the spectroscopic and X-ray crystallographic methods. The faster H-D exchange reaction of thiamin C2 proton observed in the presence of indole than in the lack would be resulted from the pi-pi charge-transfer interaction between the indole ring and the thiazolium ring of thiamin.

Chemical Phenomena↗
PubMed1991

Structure elucidation of acid reaction products of indole-3-carbinol: detection in vivo and enzyme induction in vitro.

The potency of indole-3-carbinol (I3C) to form condensation products under acidic aqueous conditions was studied. After identifying a known dimer, 3,3'-diindolylmethane (DIM), we elucidated the structures of two trimers also found in acid reaction mixtures: 5,6,11,12,17,18-hexahydrocyclonona[1,2-b:4,5-b':7,8-b"]tri-indole (CTI), and 2,3-bis[3-indolylmethyl] indole (BII). The formation of these indole oligomers was shown to be pH dependent. The highest amounts of DIM and BII were formed in aqueous solutions having a pH value ranging from 4 to 5. No CTI could be detected at pH values above 4.5. In rats that received an oral dose of I3C we could detect DIM and BII in gastric contents, stomach tissue, small intestine and liver. No CTI could be detected in vivo after oral exposure to I3C. In in vitro experiments, using rat hepatocytes, the cytochrome P-450IA1 apoprotein level, 7-ethoxyresorufin O-deethylation activity (EROD) and DT-diaphorase activity (DTD) were markedly enhanced by DIM and CTI as well as BII.

Animals↗
PubMed1989

Effect of L-cysteine on the long-term depletion of brain indoles caused by p-chloroamphetamine and d-fenfluramine in rats. Relation to brain drug concentrations.

The effect of L-cysteine on the depletion of serotonin and 5-hydroxyindoleacetic acid concentrations caused by p-chloroamphetamine and d-fenfluramine was studied in various brain regions one week after drug injection. p-Chloroamphetamine (2.5 and 5 mg/kg i.p.) and d-fenfluramine (13.4 mg/kg i.p.) significantly reduced serotonin and 5-hydroxyindoleacetic acid levels in the striatum, hippocampus and cortex, particularly in the latter areas. L-cysteine (500 mg/kg i.p.), administered 30 min before and 5 h after p-chloroamphetamine or d-fenfluramine, significantly reduced the effect of either drug on the concentrations of both indoles without causing any effect by itself. In another experiment, the rats were treated as above and were killed at various times after p-chloroamphetamine or d-fenfluramine injection to determine, in parallel, the indole levels in the whole brain and the concentration of p-chloroamphetamine, d-fenfluramine and its metabolite d-norfenfluramine in the plasma and brain. p-Chloroamphetamine and d-fenfluramine markedly lowered both indoles, particularly 16 and 24 h after injection. L-cysteine had no effect on the indole concentrations but significantly reduced the effect of p-chloroamphetamine, d-fenfluramine 16 and 24 h after injection. At these times, the brain concentrations of p-chloroamphetamine, d-fenfluramine and d-norfenfluramine were markedly lower in the L-cysteine-treated than in the control rats. Analysis of the blood concentration of p-chloroamphetamine, d-fenfluramine and d-norfenfluramine showed that the rats treated with L-cysteine eliminated the drugs studied more rapidly than the control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Amphetamines↗
PubMed1993

The role of d-norfenfluramine in the indole-depleting effect of d-fenfluramine in the rat.

The importance of d-norfenfluramine in regard to the indole-depleting action of d-fenfluramine has not been well studied in sensitive animal species. The present study therefore examined the intensity and time course of the neurochemical effects of i.p. injected d-fenfluramine (2.5 and 5 mg/kg) and d-norfenfluramine (2.5 mg/kg) in vehicle- and SKF-525A-pretreated rats, relating the effects to the brain concentration-time profiles of the drug and its active metabolite. At the lower dose d-fenfluramine caused only a small, short-lasting decrease in brain serotonin (5-HT) without affecting the 5-hydroxyindoleacetic acid (5-HIAA). Higher doses affected both 5-HT and 5-HIAA (50-60 and 30-40% reductions, respectively), the effect being maximal for at least 8 h. d-Norfenfluramine reduced the brain content of 5-HT and 5-HIAA less (by about 30%) than 5 mg/kg d-fenfluramine did. Brain concentrations of d-norfenfluramine at the time of the maximal depletion of indoles were close to those of the metabolite after 5 mg/kg d-fenfluramine, indicating that the acute indole-depleting effects did not depend solely on the brain concentrations of its nor-metabolite. SKF-525A changed the metabolite-to-parent drug ratios in brain without appreciably influencing the action of d-fenfluramine. However, the maximum decrease in indole content caused by 2.5 mg/kg d-fenfluramine in SKF-525A-pretreated rats was only 12% of the control level, although the brain concentration of unchanged drug was comparable to that after 5 mg/kg d-fenfluramine in vehicle-pretreated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Separation of tryptophan and related indoles by micellar electrokinetic chromatography with KrF laser-induced fluorescence detection.

Micellar electrokinetic chromatography (MEKC) was applied for the separation of tryptophan and related indoles. Using a 5 mM sodium borate buffer (pH 9.2) containing 50 mM sodium dodecyl sulfate and 5% acetonitrile, eleven indoles were baseline separated in under 17 min. Most of the indoles were detected at the nM level by native fluorescence using KrF laser-induced fluorescence (LIF), which was approximately 100 times more sensitive than UV absorption detection at 200 nm. Preliminary results show that the MEKC-LIF with direct sample injection is a feasible method for assessing indole profiles in diluted urine and serum.

Electrophoresis, Capillary↗
PubMed1992

Effect of escalating doses of d-fenfluramine on the content of indoles in brain.

The neurochemical effects of a large dose challenge (5 mg/kg, i.p.) of d-fenfluramine (d-F) in rats, given saline or gradually escalating doses of d-F (0.1-2.5 mg/kg, i.p.), were examined with regard to regional sensitivity and the time-course of recovery. The indole-depleting effect after the large dose of d-F to saline-pretreated animals appeared to differ, depending on the areas of brain considered (cortex greater than hippocampus greater than striatum), despite the fact that the drug and its main metabolite, d-norfenfluramine (d-NF) distributed almost uniformly in the regions of brain examined. The depletion in all these regions of the brain was reversible within 6 weeks, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) being back to control levels in the hippocampus and striatum but not 5-HT in the cortex. However, when rats were exposed to gradually escalating doses of d-F the recovery of indoles in the brain, after injection of the large dose challenge, appeared to be faster. Indoles were markedly less reduced 1 week later in the cortex, hippocampus and striatum, with content of indole in the striatum showing complete recovery and the long-term depletion of 5-HT and 5-HIAA, by the subsequent large dose challenge was almost completely reversed in all regions. Analysis of the concentrations of d-F and its main metabolite d-fenfluramine (d-NF) in brain excluded any pharmacokinetic tolerance. These results suggest that during therapeutic treatment with d-F, the use of escalating doses may attenuate the potential for the long-lasting decrease of 5-HT in brain.

Animals↗
PubMed1988

Modulation of diethylnitrosamine-induced hepatocarcinogenesis and O6-ethylguanine formation in rainbow trout by indole-3-carbinol, beta-naphthoflavone, and Aroclor 1254.

Rainbow trout were fed a diet containing indole-3-carbinol (2000 ppm), beta-naphthoflavone (500 ppm), or Aroclor 1254 (100 ppm) for 6 weeks before a single 24-hr exposure to an aqueous solution of 250 ppm diethylnitrosamine (DEN). The fish were killed 42 weeks later to determine the carcinogenic response. DEN exposure produced an 80.2% incidence of liver tumors and an average of 3.47 tumors per tumor-bearing fish, whereas no tumors were detected in the sham-treated control fish. Tumor induction was inhibited by indole-3-carbinol (27.5% incidence, 1.89 tumors per tumor-bearing fish) but enhanced by beta-naphthoflavone (91.8% incidence, 3.60 tumors per tumor-bearing fish). Aroclor 1254 had no effect on DEN-induced hepatocarcinogenesis (80.0% incidence, 3.03 tumors per tumor-bearing fish). The effects of these modulators on O6-ethylguanine and 7-ethylguanine formation (measured by HPLC and fluorescence spectrophotometry) were examined. Liver DNA ethylguanine levels were reduced in indole-3-carbinol-pretreated fish and increased in beta-naphthoflavone-pretreated fish compared to untreated controls after DEN exposure. Aroclor 1254 pretreatment had no significant effect on DNA ethylguanine formation. Similar O6-ethylguanine to 7-ethylguanine ratios were found among the control and treated groups. The results of this study indicate that modulation of DEN hepatocarcinogenesis by indole-3-carbinol and beta-naphthoflavone may be mediated by their effects on O6-ethylguanine formation and, therefore, on the initiation phase of carcinogenesis.

Animals↗
PubMed1979

Inhibition of tyrosinase by indole compounds and reaction products. Protection by albumin.

Tyrosinase activity decreases as the reaction proceeds and is inhibited by L-3,4-dihydroxyphenylalanine oxidation products. Indole and tryptophan inhibit tyrosinase reaction and bovine albumin protects against end-product(s) inhibition or inactivation. Since the same tyrosinase reaction products are indole compounds and some authors reported the binding of indole derivatives with albumin, it is here suggested that indole intermediates of melanin synthesis inhibit or inactivate tyrosinase.

Basidiomycota↗
PubMed1993

High-performance liquid chromatographic method for the determination of 3-methylindole (skatole) and indole in adipose tissue of pigs.

A rapid method for the determination of skatole (3-methylindole) and indole in adipose tissue of pigs by reversed-phase high-performance liquid chromatography has been developed. Tissue samples were melted in a microwave oven, and 100 microliters of the liquid fat were dissolved in 1 ml of n-hexane and extracted with acetonitrile-water (75:25, v/v). Portions of 100 microliters of the solution were used for chromatographic analysis. Elution was performed on a reversed-phase column with a mobile phase composed of acetic acid and isopropanol (70:30, v/v). A fluorescence detector was used for quantification. The detection limit was 4 ng/g fat. The mean recoveries of added amounts of skatole and indole were 98.9 and 93.8%, respectively. The mean coefficients of variation were: inter-assay, 6.6% (skatole) and 8.8% (indole); intra-assay, 4.2% (skatole) and 2.9% (indole). Mean skatole concentrations in fat samples from boars (40 ng/g; n = 349) were not significantly higher than those from barrows (24 ng/g; n = 98).

Adipose Tissue↗