RESUMO
The bile acid-liver-gut microbiota axis plays an important role in the host's health. The gut microbiota has an impact on the bile acid pool, but also the bile acids themselves can influence the gut microbiota composition. In this study, six antibiotics from five different classes (i.e. lincosamides, glycopeptides, macrolides, fluoroquinolones, aminoglycosides) were used to modulate microbial communities of Wistar rats to elucidate changes in the bile acid metabolism and to identify key metabolites in the bile acid pool related to gut microbial changes. 20 primary and secondary bile acids were analyzed in plasma and feces of control and treated animals. Antibiotics treatment induced significant changes in primary and secondary bile acids in both matrices. Taurine-conjugated primary bile acids significantly increased in plasma and feces. Contrary, cholic acid and most of the analyzed secondary bile acids significantly decreased in plasma, and cholic acid accumulated in the feces after treatment with all antibiotics but roxithromycin. Despite the different activity spectra of the antibiotics applied against gut microbes, the overall effect on the bile acid pool tended to be similar in both matrices except for streptomycin. These results show that changes in the gut microbial community affect the bile acid pool in plasma and feces and that changes in the bile acid profile can be indicative of alterations of the gut microbiome. Due to the important role of bile acids for the host, changes in the bile acid pool can have severe consequences for the host.
Assuntos
Antibacterianos/efeitos adversos , Ácidos e Sais Biliares/metabolismo , Microbioma Gastrointestinal/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Administração Oral , Animais , Antibacterianos/administração & dosagem , Ácidos e Sais Biliares/análise , Fezes/química , Feminino , Microbioma Gastrointestinal/fisiologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , Metabolômica , Modelos Animais , Ratos , Ratos WistarRESUMO
The metabolic functionality of the gut microbiota contributes to the metabolism and well-being of its host, although detailed insight in the microbiota's metabolism is lacking. Omics technologies could facilitate unraveling metabolism by the gut microbiota. In this study, we performed metabolite profiling of different matrices of the gut, after antibiotic treatment of rats in order to evaluate metabolite changes observed at different dose levels and in different sexes, and to identify the best tissue matrix for further investigations regarding an assessment of metabolic effects of new compounds with antibiotic activity. Three different antibiotics (vancomycin, streptomycin and roxithromycin) were administered orally to rats for 28â¯days according to the OECD 407 guideline with a subsequent metabolic profiling in feces, cecum content and gut tissue (jejunum, ileum, cecum, colon and rectum). The data were analyzed in the MetaMap®Tox database. Treatment-related effects could be observed in the metabolite profile of feces and cecum content, but not of the different gut tissues. The metabolite profile showed compound specific effects on the microbiome. In line with the activity spectra of the antibiotics tested, vancomycin showed the largest effects, followed by roxithromycin and then by streptomycin for which changes were modest. In general, for all antibiotics the largest changes were observed for the classes of lipids (increase up to 94-fold), bile acids (increase up to 33-fold), amino acids (increase up to 200-fold) and amino acid related (increase up to 348-fold). The most relevant changes in metabolite values were similar in feces and cecum content and among sexes. The results of this targeted analysis indicate that the metabolic profiles of male and female animals in the gut microbiome are comparable. Concluding, taking other samples than feces does not add any extra information. Thus, as a non-invasive sampling method, feces provide a suitable matrix for studies on metabolism by the gut microbiota.
Assuntos
Antibacterianos/toxicidade , Ceco/efeitos dos fármacos , Ceco/microbiologia , Fezes/química , Microbioma Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/microbiologia , Aminoácidos/metabolismo , Animais , Ácidos e Sais Biliares/metabolismo , Ceco/metabolismo , Feminino , Trato Gastrointestinal/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , Ratos , Roxitromicina/toxicidade , Estreptomicina/toxicidade , Vancomicina/toxicidadeRESUMO
The intestinal microbiota contributes to the metabolism of its host. Adequate identification of the microbiota's impact on the host plasma metabolites is lacking. As antibiotics have a profound effect on the microbial composition and hence on the mammalian-microbiota co-metabolism, we studied the effects of antibiotics on the "functionality of the microbiome"-defined as the production of metabolites absorbed by the host. This metabolomics study presents insights into the mammalian-microbiome co-metabolism of endogenous metabolites. To identify plasma metabolites related to microbiome changes due to antibiotic treatment, we have applied broad-spectrum antibiotics belonging to the class of aminoglycosides (neomycin, gentamicin), fluoroquinolones (moxifloxacin, levofloxacin) and tetracyclines (doxycycline, tetracycline). These were administered orally for 28 days to male rats including blood sampling for metabolic profiling after 7, 14 and 28 days. Fluoroquinolones and tetracyclines can be absorbed from the gut; whereas, aminoglycosides are poorly absorbed. Hippuric acid, indole-3-acetic acid and glycerol were identified as key metabolites affected by antibiotic treatment, beside changes mainly concerning amino acids and carbohydrates. Inter alia, effects on indole-3-propionic acid were found to be unique for aminoglycosides, and on 3-indoxylsulfate for tetracyclines. For each class of antibiotics, specific metabolome patterns could be established in the MetaMap®Tox data base, which contains metabolome data for more than 550 reference compounds. The results suggest that plasma-based metabolic profiling (metabolomics) could be a suitable tool to investigate the effect of antibiotics on the functionality of the microbiome and to obtain insight into the mammalian-microbiome co-metabolism.
Assuntos
Antibacterianos/farmacologia , Sangue/metabolismo , Microbioma Gastrointestinal/efeitos dos fármacos , Metaboloma/efeitos dos fármacos , Aminoglicosídeos/farmacologia , Animais , Sangue/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Ingestão de Alimentos/efeitos dos fármacos , Fluoroquinolonas/farmacologia , Glicerol/sangue , Hipuratos/sangue , Indicã/sangue , Ácidos Indolacéticos/sangue , Metabolômica/métodos , Ratos Wistar , Tetraciclinas/farmacologiaRESUMO
Acyclic α,ß-unsaturated aldehydes present in food raise a concern because the α,ß-unsaturated aldehyde moiety is considered a structural alert for genotoxicity. However, controversy remains on whether in vivo at realistic dietary exposure DNA adduct formation is significant. The aim of the present study was to develop physiologically based kinetic/dynamic (PBK/D) models to examine dose-dependent detoxification and DNA adduct formation of a group of 18 food-borne acyclic α,ß-unsaturated aldehydes without 2- or 3-alkylation, and with no more than one conjugated double bond. Parameters for the PBK/D models were obtained using quantitative structure-activity relationships (QSARs) defined with a training set of six selected aldehydes. Using the QSARs, PBK/D models for the other 12 aldehydes were defined. Results revealed that DNA adduct formation in the liver increases with decreasing bulkiness of the molecule especially due to less efficient detoxification. 2-Propenal (acrolein) was identified to induce the highest DNA adduct levels. At realistic dietary intake, the predicted DNA adduct levels for all aldehydes were two orders of magnitude lower than endogenous background levels observed in disease free human liver, suggesting that for all 18 aldehydes DNA adduct formation is negligible at the relevant levels of dietary intake. The present study provides a proof of principle for the use of QSAR-based PBK/D modelling to facilitate group evaluations and read-across in risk assessment.
Assuntos
Aldeídos/toxicidade , Adutos de DNA/metabolismo , Dieta/efeitos adversos , Contaminação de Alimentos , Fígado/efeitos dos fármacos , Modelos Moleculares , Relação Quantitativa Estrutura-Atividade , Aldeídos/química , Aldeídos/metabolismo , Animais , Relação Dose-Resposta a Droga , Humanos , Inativação Metabólica , Cinética , Fígado/metabolismo , Estrutura Molecular , Ratos , Medição de RiscoRESUMO
The metabolic fate of a compound is determined by numerous factors including its chemical structure. Although the metabolic options for a variety of functional groups are well understood and can often provide a rationale for the comparison of toxicity based on structural analogy, at times quite minor structural variations may have major consequences for metabolic outcomes and toxicity. In this perspective, the effects of structural variations on metabolic outcomes is detailed for a group of related hydroxy- and alkoxy-substituted allyl- and propenylbenzenes. These classes of compounds are naturally occurring constituents of a variety of botanical-based food items. The classes vary from one another by the presence or absence of alkylation of their para-hydroxyl substituents and/or the position of the double bond in the alkyl side chain. We provide an overview of how these subtle structural variations alter the metabolism of these important food-borne compounds, ultimately influencing their toxicity, particularly their DNA reactivity and carcinogenic potential. The data reveal that detailed knowledge of the consequences of subtle structural variations for metabolism is essential for adequate comparison of structurally related chemicals. Taken together, it is concluded that predictions in toxicological risk assessment should not be performed on the basis of structural analogy only but should include an analogy of metabolic pathways across compounds and species.
Assuntos
Derivados de Benzeno , Carcinógenos , Animais , Derivados de Benzeno/química , Derivados de Benzeno/farmacocinética , Derivados de Benzeno/toxicidade , Biotransformação , Carcinógenos/química , Carcinógenos/farmacocinética , Carcinógenos/toxicidade , HumanosRESUMO
A number of α,ß-unsaturated aldehydes are present in food both as natural constituents and as flavouring agents. Their reaction with DNA due to their electrophilic α,ß-unsaturated aldehyde moiety may result in genotoxicity as observed in some in vitro models, thereby raising a safety concern. A question that remains is whether in vivo detoxification would be efficient enough to prevent DNA adduct formation and genotoxicity. In this study, a human physiologically based kinetic/dynamic (PBK/D) model of trans-2-hexenal (2-hexenal), a selected model α,ß-unsaturated aldehyde, was developed to examine dose-dependent detoxification and DNA adduct formation in humans upon dietary exposure. The kinetic model parameters for detoxification were quantified using relevant pooled human tissue fractions as well as tissue fractions from 11 different individual subjects. In addition, a Monte Carlo simulation was performed so that the impact of interindividual variation in 2-hexenal detoxification on the DNA adduct formation in the population as a whole could be examined. The PBK/D model revealed that DNA adduct formation due to 2-hexenal exposure was 0.039 adducts/108 nucleotides (nt) at the estimated average 2-hexenal dietary intake (0.04 mg 2-hexenal/kg bw) and 0.18 adducts/108 nt at the 95th percentile of the dietary intake (0.178 mg 2-hexenal/kg bw) in the most sensitive people. These levels are three orders of magnitude lower than natural background DNA adduct levels that have been reported in disease-free humans (6.8-110 adducts/108 nt), suggesting that the genotoxicity risk for the human population at realistic dietary daily intakes of 2-hexenal may be negligible.
Assuntos
Aldeídos/metabolismo , Dieta/efeitos adversos , Sistemas Inteligentes , Aromatizantes/metabolismo , Intestino Delgado/enzimologia , Fígado/enzimologia , Modelos Biológicos , Aldeídos/efeitos adversos , Aldeídos/sangue , Aldeídos/farmacocinética , Animais , Biologia Computacional , Citosol/enzimologia , Citosol/metabolismo , Adutos de DNA/metabolismo , Aromatizantes/efeitos adversos , Aromatizantes/farmacocinética , Humanos , Inativação Metabólica , Intestino Delgado/metabolismo , Cinética , Fígado/metabolismo , Microssomos/enzimologia , Microssomos/metabolismo , Método de Monte Carlo , Testes de Mutagenicidade , Ratos , Reprodutibilidade dos Testes , Medição de Risco/métodosRESUMO
A physiologically based biokinetic (PBBK) model for alkenylbenzene safrole in rats was developed using in vitro metabolic parameters determined using relevant tissue fractions. The performance of the model was evaluated by comparison of the predicted levels of 1,2-dihydroxy-4-allylbenzene and 1'-hydroxysafrole glucuronide to levels of these metabolites reported in the literature to be excreted in the urine of rats exposed to safrole and by comparison of the predicted amount of total urinary safrole metabolites to the reported levels of safrole metabolites in the urine of safrole exposed rats. These comparisons revealed that the predictions adequately match observed experimental values. Next, the model was used to predict the relative extent of bioactivation and detoxification of safrole at different oral doses. At low as well as high doses, P450 mediated oxidation of safrole mainly occurs in the liver in which 1,2-dihydroxy-4-allylbenzene was predicted to be the major P450 metabolite of safrole. A dose dependent shift in P450 mediated oxidation leading to a relative increase in bioactivation at high doses was not observed. Comparison of the results obtained for safrole with the results previously obtained with PBBK models for the related alkenylbenzenes estragole and methyleugenol revealed that the overall differences in bioactivation of the three alkenylbenzenes to their ultimate carcinogenic 1'-sulfooxy metabolites are limited. This is in line with the generally less than 4-fold difference in their level of DNA binding in in vitro and in vivo studies and their almost similar BMDL(10) values (lower confidence limit of the benchmark dose that gives 10% increase in tumor incidence over background level) obtained in in vivo carcinogenicity studies. It is concluded that in spite of differences in the rates of specific metabolic conversions, overall the levels of bioactivation of the three alkenylbenzenes are comparable which is in line with their comparable carcinogenic potential.
Assuntos
Aditivos Alimentares/metabolismo , Mutagênicos/metabolismo , Safrol/análogos & derivados , Safrol/metabolismo , Compostos Alílicos/metabolismo , Derivados de Alilbenzenos , Animais , Anisóis/metabolismo , Derivados de Benzeno/metabolismo , Sistema Enzimático do Citocromo P-450/metabolismo , Eugenol/análogos & derivados , Eugenol/metabolismo , Glucuronídeos/metabolismo , Cinética , Masculino , Modelos Biológicos , Oxirredução , Ratos , Ratos Sprague-DawleyRESUMO
Estragole is a natural constituent of several herbs and spices including sweet basil. In rodent bioassays, estragole induces hepatomas, an effect ascribed to estragole bioactivation to 1'-sulfooxyestragole resulting in DNA adduct formation. The present paper identifies nevadensin as a basil constituent able to inhibit DNA adduct formation in rat hepatocytes exposed to the proximate carcinogen 1'-hydroxyestragole and nevadensin. This inhibition occurs at the level of sulfotransferase (SULT)-mediated bioactivation of 1'-hydroxyestragole. The Ki for SULT inhibition by nevadensin was 4 nM in male rat and human liver fractions. Furthermore, nevadensin up to 20 microM did not inhibit 1'-hydroxyestragole detoxification by glucuronidation and oxidation. The inhibition of SULT by nevadensin was incorporated into the recently developed physiologically based biokinetic (PBBK) rat and human models for estragole bioactivation and detoxification. The results predict that co-administration of estragole at a level inducing hepatic tumors in vivo (50mg/kg bw) with nevadensin at a molar ratio of 0.06, representing the ratio of their occurrence in basil, results in almost 100% inhibition of the ultimate carcinogen 1'-sulfooxyestragole when assuming 100% uptake of nevadensin. Assuming 1% uptake, inhibition would still amount to more than 83%. Altogether these data point at a nevadensin-mediated inhibition of the formation of the ultimate carcinogenic metabolite of estragole, without reducing the capacity to detoxify 1'-hydroxyestragole via glucuronidation or oxidation. These data also point at a potential reduction of the cancer risk when estragole exposure occurs within a food matrix containing SULT inhibitors compared to what is observed upon exposure to pure estragole.
Assuntos
Anisóis/farmacocinética , Carcinógenos/farmacocinética , Flavonas/farmacologia , Ocimum basilicum , Sulfotransferases/antagonistas & inibidores , Derivados de Alilbenzenos , Animais , Anisóis/metabolismo , Adutos de DNA/metabolismo , Relação Dose-Resposta a Droga , Glucuronídeos/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Humanos , Técnicas In Vitro , Masculino , Modelos Biológicos , Oxirredução , Extratos Vegetais , Ratos , Ratos Sprague-Dawley , Testes de Toxicidade AgudaRESUMO
This study investigates the importance of the intracellular ratio of the two estrogen receptors ERalpha and ERbeta for the ultimate potential of the phytoestrogens genistein and quercetin to stimulate or inhibit cancer cell proliferation. This is of importance because (i) ERbeta has been postulated to play a role in modulating ERalpha-mediated cell proliferation, (ii) genistein and quercetin may be agonists for both receptor types and (iii) the ratio of ERalpha to ERbeta is known to vary between tissues. Using human osteosarcoma (U2OS) ERalpha or ERbeta reporter cells it was shown that compared to estradiol (E2), genistein and quercetin have not only a relatively greater preference for ERbeta but also a higher maximal potential for activating ERbeta-mediated gene expression. Using the human T47D breast cancer cell line with tetracycline-dependent ERbeta expression (T47D-ERbeta), the effect of a varying intracellular ERalpha/ERbeta ratio on E2- or pythoestrogen-induced cell proliferation was characterised. E2-induced proliferation of cells in which ERbeta expression was inhibited was similar to that of the T47D wild type cells, whereas this E2-induced cell proliferation was no longer observed when ERbeta expression was increased. With increased expression of ERbeta the phytoestrogen-induced cell proliferation was also reduced. These results point at the importance of the cellular ERalpha/ERbeta ratio for the ultimate effect of (phyto)estrogens on cell proliferation.
Assuntos
Proliferação de Células/efeitos dos fármacos , Receptor alfa de Estrogênio/fisiologia , Receptor beta de Estrogênio/fisiologia , Genisteína/farmacologia , Fitoestrógenos/farmacologia , Quercetina/farmacologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Estradiol/farmacologia , Receptor beta de Estrogênio/antagonistas & inibidores , Humanos , Tetraciclina/farmacologiaRESUMO
This publication is the 12th in a series of safety evaluations performed by the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA). In 1993, the Panel initiated a comprehensive program to re-evaluate the safety of more than 1700 GRAS flavoring substances under conditions of intended use. Since then, the number of flavoring substances has grown to more than 2200 chemically-defined substances. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, toxicodynamics and toxicology. Scientific data relevant to the safety evaluation for the use of aliphatic, linear alpha,beta-unsaturated aldehydes and structurally related substances as flavoring ingredients are evaluated. The group of substances was reaffirmed as GRAS (GRASr) based, in part, on their self-limiting properties as flavoring substances in food; their low level of flavor use; the rapid absorption and metabolism of low in vivo concentrations by well-recognized biochemical pathways; adequate metabolic detoxication at much higher levels of exposure in humans and animals; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic and chronic studies. While some of the compounds described here have exhibited positive in vitro genotoxicity results, evidence of in vivo genotoxicity and carcinogenicity occurs only under conditions in which animals are repeatedly and directly exposed to high irritating concentrations of the aldehyde. These conditions are not relevant to humans who consume alpha,beta-unsaturated aldehydes as flavor ingredients at low concentrations distributed in a food or beverage matrix.
Assuntos
Aldeídos/toxicidade , Aromatizantes/toxicidade , Aldeídos/análise , Aldeídos/química , Aldeídos/farmacocinética , Animais , Carcinógenos/análise , Carcinógenos/toxicidade , Aromatizantes/análise , Aromatizantes/química , Aromatizantes/farmacocinética , Análise de Alimentos , Humanos , Mutagênicos/análise , Mutagênicos/toxicidade , Reprodução/efeitos dos fármacosRESUMO
The importance of the gut microorganisms and their wide range of interactions with the host are well-acknowledged. In this study, lincomycin and clindamycin were used to modulate microbial communities of Wistar rats to gain a comprehensive understanding of the implications of microbiome alterations. A metabolomics approach and taxonomic profiling were applied to characterize the effects of these antibiotics on the functionality of the microbiome and to identify microbiome-related metabolites. After treatment, the diversity of the microbial community was drastically reduced. Bacteroidetes and Verrucomicrobia were drastically reduced, Tenericutes and Deferribacteres completely disappeared, while abundance of Firmicutes and Proteobacteria were highly increased. Changes in plasma and feces metabolites were observed for metabolites belonging mainly to the class of complex lipids, fatty acids and related metabolites as well as amino acids and related compounds. Bile acid metabolism was markedly affected: taurocholic acid, glycochenodeoxycholic acid and cholic acid presented abrupt changes showing a specific metabolite pattern indicating disruption of the microbial community. In both plasma and feces taurocholic acid was highly upregulated upon treatment whereas glycochenodeoxycholic acid was downregulated. Cholic acid was upregulated in feces but downregulated in plasma. These results show that changes in the gut microbial community lead to alterations of the metabolic profile in blood and feces of the host and can be used to identify potentially microbiome-related metabolites. This implies that metabolomics could be a suitable tool to estimate the extent of changes induced in the intestinal microbiome with respect to consequences for the host.
Assuntos
Antibacterianos/farmacologia , Fezes/química , Microbioma Gastrointestinal/efeitos dos fármacos , Lincosamidas/farmacologia , Animais , Bactérias/classificação , Bactérias/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Biologia Computacional , Ingestão de Alimentos/efeitos dos fármacos , Feminino , Metabolismo dos Lipídeos/efeitos dos fármacos , Masculino , Metaboloma/efeitos dos fármacos , Metabolômica , Ratos , Ratos Wistar , Caracteres SexuaisRESUMO
Genotoxicity of α,ß-unsaturated aldehydes shown in vitro raises a concern for the use of the aldehydes as food flavourings, while at low dose exposures the formation of DNA adducts may be prevented by detoxification. Unlike many α,ß-unsaturated aldehydes for which in vivo data are absent, cinnamaldehyde was shown to be not genotoxic or carcinogenic in vivo. The present study aimed at comparing dose-dependent DNA adduct formation by cinnamaldehyde and 18 acyclic food-borne α,ß-unsaturated aldehydes using physiologically based kinetic/dynamic (PBK/D) modelling. In rats, cinnamaldehyde was predicted to induce higher DNA adducts levels than 6 out of the 18 α,ß-unsaturated aldehydes, indicating that these 6 aldehydes may also test negative in vivo. At the highest cinnamaldehyde dose that tested negative in vivo, cinnamaldehyde was predicted to form at least three orders of magnitude higher levels of DNA adducts than the 18 aldehydes at their respective estimated daily intake. These results suggest that for all the 18 α,ß-unsaturated aldehydes DNA adduct formation at doses relevant for human dietary exposure may not raise a concern. The present study illustrates a possible use of physiologically based in silico modelling to facilitate a science-based comparison and read-across on the possible risks posed by DNA reactive agents.
Assuntos
Aldeídos/toxicidade , Adutos de DNA , Aromatizantes/toxicidade , Modelos Biológicos , Mutagênicos/toxicidade , Álcool Desidrogenase/metabolismo , Aldeído Desidrogenase/metabolismo , Aldeído Redutase/metabolismo , Animais , Simulação por Computador , Dieta , Feminino , Glutationa/metabolismo , Glutationa Transferase/metabolismo , Humanos , Intestino Delgado/metabolismo , Fígado/metabolismo , Masculino , Ratos Sprague-DawleyRESUMO
Soy isoflavones (SIF) are present in the systemic circulation as conjugated forms of which the estrogenic potency is not yet clear. The present study provides evidence that the major SIF glucuronide metabolites in blood, genistein-7-O-glucuronide (GG) and daidzein-7-O-glucuronide (DG), only become estrogenic after deconjugation. The estrogenic potencies of genistein (Ge), daidzein (Da), GG and DG were determined using stably transfected U2OS-ERα, U2OS-ERß reporter gene cells and proliferation was tested in T47D-ERß cells mimicking the ERα/ERß ratio of healthy breast cells and inT47D breast cancer cells. In all assays applied, the estrogenic potency of the aglycones was significantly higher than that of their corresponding glucuronides. UPLC analysis revealed that in U2OS and T47D cells, 0.2-1.6% of the glucuronides were deconjugated to their corresponding aglycones. The resulting aglycone concentrations can account for the estrogenicity observed upon glucuronide exposure. Interestingly, under similar experimental conditions, rat breast tissue S9 fraction was about 30 times more potent in deconjugating these glucuronides than human breast tissue S9 fraction. Our study confirms that SIF glucuronides are not estrogenic as such, and that the small % of deconjugation in the cell is enough to explain the slight bioactivity observed for the SIF-glucuronides. Species differences in deconjugation capacity should be taken into account when basing risk-benefit assessment of these SIF for the human population on animal data.
Assuntos
Estrogênios não Esteroides/farmacologia , Glycine max/química , Isoflavonas/farmacologia , Animais , Mama/citologia , Mama/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Feminino , Genes Reporter/efeitos dos fármacos , Genisteína/farmacologia , Glucuronídeos/química , Glucuronídeos/farmacologia , Humanos , Isoflavonas/química , Ratos , Frações Subcelulares/metabolismoRESUMO
The biological Baeyer-Villiger oxidation of acetophenones was studied by (19)F nuclear magnetic resonance (NMR). The (19)F NMR method was used to characterise the time-dependent conversion of various fluorinated acetophenones in either whole cells of Pseudomonas fluorescens ACB or in incubations with purified 4'-hydroxyacetophenone monooxygenase (HAPMO). Whole cells of P. fluorescens ACB converted 4'-fluoroacetophenone to 4-fluorophenol and 4'-fluoro-2'-hydroxyacetophenone to 4-fluorocatechol without the accumulation of 4'-fluorophenyl acetates. In contrast to 4-fluorophenol, 4-fluorocatechol was further degraded as evidenced by the formation of stoichiometric amounts of fluoride anion. Purified HAPMO catalysed the strictly NADPH-dependent conversion of fluorinated acetophenones to fluorophenyl acetates. Incubations with HAPMO at pH 6 and 8 showed that the enzymatic Baeyer-Villiger oxidation occurred faster at pH 8 but that the phenyl acetates produced were better stabilised at pH 6. Quantum mechanical characteristics explained why 4'-fluoro-2'-hydroxyphenyl acetate was more sensitive to base-catalysed hydrolysis than 4'-fluorophenyl acetate. All together, (19)F NMR proved to be a valid method to evaluate the biological conversion of ring-substituted acetophenones to the corresponding phenyl acetates, which can serve as valuable synthons for further production of industrially relevant chemicals.
RESUMO
Of all NMR-observable isotopes (19)F is the one most convenient for studies on the biodegradation of environmental pollutants and especially for fast initial metabolic screening of newly isolated organisms. In the past decade we have identified the (19)F NMR characteristics of many fluorinated intermediates in the microbial degradation of fluoroaromatics including especially fluorophenols. In the present paper we give an overview of results obtained for the initial steps in the aerobic microbial degradation of fluorophenols, i.e. the aromatic hydroxylation to di-, tri- or even tetrahydroxybenzenes ultimately suitable as substrates for the second step, ring cleavage by dioxygenases. In addition we present new results from studies on the identification of metabolites resulting from reaction steps following aromatic ring cleavage, i.e. resulting from the conversion of fluoromuconates by chloromuconate cycloisomerase. Together the presented data illustrate the potential of the (19)F NMR technique for (1) fast initial screening of biodegradative pathways, i.e. for studies on metabolomics in newly isolated microorganisms, and (2) identification of relatively unstable pathway intermediates like fluoromuconolactones and fluoromaleylacetates.
RESUMO
Dietary flavonoids may protect against cardiovascular diseases (CVD). Increased circulating lipid levels and hepatic lipid accumulation are known risk factors for CVD. The aim of this study was to investigate the effects and underlying molecular mechanisms of the flavonoid quercetin on hepatic lipid metabolism in mice with high-fat diet induced body weight gain and hepatic lipid accumulation. Adult male mice received a 40 energy% high-fat diet without or with supplementation of 0.33 % (w/w) quercetin for 12 weeks. Body weight gain was 29 % lower in quercetin fed mice (p < 0.01), while the energy intake was not significantly different. Quercetin supplementation lowered hepatic lipid accumulation to 29 % of the amount present in the control mice (p < 0.01). (1)H nuclear magnetic resonance serum lipid profiling revealed that the supplementation significantly lowered serum lipid levels. Global gene expression profiling of liver showed that cytochrome P450 2b (Cyp2b) genes, key target genes of the transcription factor constitutive androstane receptor (Car; official symbol Nr1i3), were downregulated. Quercetin decreased high-fat diet induced body weight gain, hepatic lipid accumulation and serum lipid levels. This was accompanied by regulation of cytochrome P450 2b genes in liver, which are possibly under transcriptional control of CAR. The quercetin effects are likely dependent on the fat content of the diet.
RESUMO
Herbal food supplements, claiming to enhance sexual potency, may contain deliberately added active pharmacological ingredients (APIs) that can be used for the treatment of erectile dysfunction (ED). The aim of this study was to determine whether herbal food supplements on the Dutch market indeed contain APIs that inhibit phosphodiesterase type 5 (PDE-5) inhibitors, such as sildenafil and analogous PDE-5 inhibitors. Herbal food supplements intended to enhance sexual potency (n = 71), and two soft drinks, were sampled from 2003 up to and including 2012. In 23 herbal supplements, nine different PDE-5 inhibitors were identified; in a few cases (n = 3), more than one inhibitor was indentified. The presence of these APIs was however not stated on the label. The concentrations of PDE-5 inhibitors per dose unit were analysed. Furthermore, the potential pharmacologically active properties of the detected PDE-5 inhibitors were estimated by using data from the scientific and patent literature regarding (1) in vitro PDE-5 activity, (2) reported effective doses of registered drugs with PDE-5 inhibitor activity and (3) similarity to other structural analogues. It was concluded that 18 of the 23 herbal food supplements, when used as recommended, would have significant pharmacological effects due to added APIs. Adequate use of existing regulation and control measures seems necessary to protect consumers against the adverse effects of these products.
Assuntos
Qualidade de Produtos para o Consumidor , Suplementos Nutricionais/análise , Contaminação de Alimentos , Inibidores da Fosfodiesterase 5/análise , Piperazinas/análise , Plantas Medicinais , Sulfonas/análise , Vasodilatadores/análise , Bebidas Gaseificadas/efeitos adversos , Bebidas Gaseificadas/análise , Bebidas Gaseificadas/economia , Qualidade de Produtos para o Consumidor/legislação & jurisprudência , Suplementos Nutricionais/efeitos adversos , Suplementos Nutricionais/economia , Disfunção Erétil/dietoterapia , Disfunção Erétil/tratamento farmacológico , Contaminação de Alimentos/legislação & jurisprudência , Rotulagem de Alimentos , Fidelidade a Diretrizes , Humanos , Internet , Legislação de Medicamentos , Legislação sobre Alimentos , Masculino , Países Baixos , Substâncias para Melhoria do Desempenho/administração & dosagem , Substâncias para Melhoria do Desempenho/química , Substâncias para Melhoria do Desempenho/farmacologia , Substâncias para Melhoria do Desempenho/uso terapêutico , Inibidores da Fosfodiesterase 5/administração & dosagem , Inibidores da Fosfodiesterase 5/farmacologia , Inibidores da Fosfodiesterase 5/uso terapêutico , Piperazinas/administração & dosagem , Piperazinas/farmacologia , Piperazinas/uso terapêutico , Vigilância em Saúde Pública , Purinas/administração & dosagem , Purinas/análise , Purinas/farmacologia , Purinas/uso terapêutico , Comportamento Sexual/efeitos dos fármacos , Citrato de Sildenafila , Sulfonas/administração & dosagem , Sulfonas/farmacologia , Sulfonas/uso terapêutico , Vasodilatadores/administração & dosagem , Vasodilatadores/farmacologia , Vasodilatadores/uso terapêuticoRESUMO
Pregnant women in Africa, Asia and Suriname, and some immigrants in Western societies, traditionally consume clay products known by a variety of names such as mabele, calabash chalk, sikor and pimba. Furthermore, clay is used for health purposes in Western societies. Because certain clays can contain high levels of metals and metalloids, the aim of this study was to determine lead, arsenic, mercury and cadmium in clay products for oral use available on the Dutch market. Traditional clays originating from Africa (n = 10) and Suriname (n = 26), and health clays (n = 27) were sampled from 2004 up to and including 2012. Total metal and metalloid contents were measured by ICP-MS and showed maximum levels of lead, arsenic, mercury and cadmium of 99.7, 45.1, 2.2 and 0.75 mg kg⻹, respectively. In the absence of maximum limits for these type of clays, the potential exposure was estimated from the determined concentration, the estimated daily use level of the clays, and the estimated bioaccessibility of the different metals and arsenic. The intake estimates were compared with existing health-based guidance values. For lead, the use of 34 of the 36 traditional clays and two of the 27 health clays would result in intake levels exceeding the toxicological limit by up to 20-fold. Use of 15 of the 35 traditional clays and 11 of the 27 health clays would result in intake levels exceeding the toxicological limit for inorganic arsenic by up to 19-fold. Although limited bioaccessibility from the clay may limit the exposure and exceedance of the health-based guidance values, it was concluded that lead and arsenic intakes from some clay products could be of concern also because of their use by pregnant women and the potential developmental toxicity. As a result the use of these products, especially by pregnant women, should be discouraged.
Assuntos
Silicatos de Alumínio/química , Arsênio/análise , Suplementos Nutricionais/análise , Contaminação de Alimentos , Metais Pesados/análise , Modelos Biológicos , África/etnologia , Silicatos de Alumínio/efeitos adversos , Silicatos de Alumínio/farmacocinética , Silicatos de Alumínio/normas , Arsênio/farmacocinética , Arsênio/toxicidade , Ásia/etnologia , Disponibilidade Biológica , Cádmio/análise , Cádmio/farmacocinética , Cádmio/toxicidade , Argila , Suplementos Nutricionais/efeitos adversos , Suplementos Nutricionais/normas , Emigrantes e Imigrantes , União Europeia , Fidelidade a Diretrizes , Guias como Assunto , Promoção da Saúde , Chumbo/análise , Chumbo/farmacocinética , Chumbo/toxicidade , Medicina Tradicional , Mercúrio/análise , Mercúrio/farmacocinética , Mercúrio/toxicidade , Metais Pesados/farmacocinética , Metais Pesados/toxicidade , Países Baixos , Pica/metabolismo , Pica/prevenção & controle , Medição de Risco , Suriname/etnologiaRESUMO
T47D-ERß breast cancer cells with tetracycline-dependent ERß expression and constant ERα expression can be used to investigate effects of varying ERα/ERß ratios on estrogen-induced cellular responses. This study defines conditions at which ERα/ERß ratios in T47D-ERß cells best mimic ERα/ERß ratios in breast and other estrogen-sensitive tissues in vivo in rat as well as in human. Protein and mRNA levels of ERα and ERß were analyzed in T47D-ERß cells exposed to a range of tetracycline concentrations and compared to ERα and ERß levels found in breast, prostate, and uterus from rat and human origin. The ERα/ERß ratio in T47D-ERß cells exposed to >150ng/ml tetracycline is comparable to the ratio found in rat mammary gland and in human breast tissue. The ERα/ERß ratio of other estrogen-sensitive rat and human tissues can also be mimicked in T47D-ERß cells. The ERα/ERß ratio found in MCF-7 and native T47D breast cancer cell lines did not reflect ratios in analyzed rat and human tissues, which further supports the use of T47D-ERß cells as model for estrogen-responsive tissues. Using 17ß-estradiol and the T47D-ERß cells under the conditions defined to mimic various tissues it could be demonstrated how these different tissues vary in their proliferative response.
Assuntos
Neoplasias da Mama/metabolismo , Mama/metabolismo , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/metabolismo , Glândulas Mamárias Animais/metabolismo , Adulto , Idoso , Animais , Linhagem Celular Tumoral , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Próstata/metabolismo , Ratos , Tetraciclina , Útero/metabolismoRESUMO
This review is an up-to-date compilation of the available literature, including scientific papers, reviews, and EFSA's opinions, on toxicity and risk assessment data on the main marine biotoxins of importance in the European Union, including the legislated ones and the ones of recent appearance which are not legislated. Information about the hazard identification and hazard characterisation of okadaic acid, dynophysistoxins, pectenotoxins, yessotoxins, azaspiracids, domoic acid, saxitoxins, tetrodotoxins, brevetoxins, ciguatoxins, cyclic imines and palytoxins is reviewed and presented in the form of a collection of risk assessments. It is concluded that the importance of having an appropriate exposure assessment reiterates the urgency of establishing a database with representative and comparable data on exposure to food items possiby containing marine biotoxins. It is also concluded that a revision of the present regulation of marine biotoxins in the EU legislation could be considered, as some regulated toxins have been shown not to pose a risk for EU's population (as yessotoxin) and some non regulated toxins have been shown to be harmful and/or to occur in the EU (as tetrodotoxin, palytoxin, and some cyclic imines) while they are not regulated.