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1.
Environ Res ; 250: 118493, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38378125

RESUMO

In low-income countries, a widespread but poorly studied type of cottage industry consists of melting scrap metal for making cookware. We assessed the exposure to lead (Pb) among artisanal workers, and their families, involved in manufacturing cookware from scrap metal. In a cross-sectional survey, we compared artisanal cookware manufacturing foundries with carpentry workshops (negative controls) and car battery repair workshops (positive controls), all located in residential areas, in Lubumbashi (DR Congo). We collected surface dust in the workspaces, and blood and urine samples among workers, as well as residents living in the cookware workshops. Trace elements were quantified in the samples by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In surface dust, median Pb concentrations were higher in cookware foundries (347 mg/kg) than in carpentries (234 mg/kg) but lower than in battery repair workshops (22,000 mg/kg). In workers making the cookware (n = 24), geometric mean (GM) Pb blood cencentration was 118 µg/L [interquartile range (IQR) 78.4-204], i.e. nearly twice as high as among carpenters [60.2 µg/L (44.4-84.7), n = 33], and half the concentration of battery repair workers [255 µg/L (197-362), n = 23]. Resident children from the cookware foundries, had higher urinary Pb [6.2 µg/g creatinine (2.3-19.3), n = 6] than adults [2.3 (2.2-2.5), n = 3]. Our investigation confirms the high Pb hazard linked to car battery repair and reveals a high exposure to Pb among artisanal cookware manufacturers and their families, especially children, in residential areas of a city in a low-income country.


Assuntos
Monitoramento Biológico , Chumbo , Exposição Ocupacional , Humanos , Chumbo/sangue , Chumbo/urina , Chumbo/análise , Adulto , Estudos Transversais , Masculino , Exposição Ocupacional/análise , Feminino , Pessoa de Meia-Idade , Utensílios de Alimentação e Culinária , Adulto Jovem , Criança , Exposição Ambiental/análise , Adolescente , Poeira/análise , Pré-Escolar
2.
Drug Test Anal ; 16(1): 99-104, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37173289

RESUMO

Whipped cream canisters, also known as nitrous oxide whippets, are traditionally used in the culinary arts to prepare food foams. In recent years, however, these gas canisters have been cracked open and inhaled to produce a "legal" high. Users of these whippets have reported the presence of an oily residue containing metallic particles. This contamination was investigated using liquid chromatography-, gas chromatography- and inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). The particulate matter was also analyzed by scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDX). The presence of cyclohexyl isothiocyanate was confirmed at a maximum concentration of 67 µg per whippet. ICP-MS and ICP-OES analysis revealed the presence of mainly iron and zinc, but also, traces of aluminum, chromium, cobalt, nickel, and lead were found. STEM-EDX analysis confirmed the presence of nano-sized particles containing iron and zinc. When simulating inhalation, using the multiple path particle dosimetry model, it was confirmed that these nano-sized particles can reach the deeper parts of the lungs. Most users assume that inhaling a food-grade nitrous oxide whippet for a "legal" high poses no risks. However, this research shows that users are exposed to cyclohexyl isothiocyanate, a substance classified as a respiratory sensitizer. The presence of zinc in the particulate matter could potentially be linked to lung lesions.


Assuntos
Drogas Ilícitas , Óxido Nitroso , Cromatografia Gasosa-Espectrometria de Massas , Zinco , Ferro , Material Particulado , Isotiocianatos
3.
Food Chem Toxicol ; 149: 112034, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33529678

RESUMO

Recently collected dietary exposure data on mineral oil saturated (MOSH) and aromatic (MOAH) hydrocarbons were used to evaluate the risks associated with exposure to mineral oil through food for the Belgian population. For MOSH, the no observed adverse effect level (NOAEL) value of 19 mg kg-1 bw day-1 based on the hepatic inflammation-associated granulomas found in a 90-day oral study in F-344 rats was used as point of departure (PoD). Due to existing toxicological uncertainties, the margin of exposure (MOE) approach was applied. In all investigated scenarios, the MOE values were well above 100, indicating that there is no direct health concern related to MOSH exposure for the Belgian population. Nevertheless, more appropriate risk assessment approaches for MOSH based on adequate PoD are needed. For dietary exposure to MOAH, which are potentially genotoxic and carcinogenic, no MOE values could be calculated due to the lack of adequate dose-response carcinogenicity data. In two investigated worst-case scenarios, a health concern related to MOAH exposure could not be excluded, highlighting that more data are needed to perform an adequate risk assessment. The possibility to use in vitro bioassays to collect such additional toxicological information for MOAH present in food samples was also investigated.


Assuntos
Dieta , Contaminação de Alimentos , Óleo Mineral/toxicidade , Adolescente , Adulto , Bélgica , Criança , Pré-Escolar , Humanos , Pessoa de Meia-Idade , Óleo Mineral/administração & dosagem , Medição de Risco , Adulto Jovem
4.
Artigo em Inglês | MEDLINE | ID: mdl-33596153

RESUMO

Despite the health benefits of food supplements (FS) based on algae or cyanobacteria, the elevated arsenic (As) concentrations in these FS may raise a health concern. In the present study 33 FS containing algae or cyanobacteria were collected and As (species) were analysed to estimate consumer exposure. Based on hazard and exposure data, potential risks were evaluated using inorganic arsenic (Asi) and the potentially toxic As fraction (Astot minus arsenobetaine (AB)). Astot concentrations were in the range 0.053-57 mg/kg with highest concentrations in FS containing brown algae. Asi concentrations were in the range <0.02-4.7 mg kg-1. A large part of As in FS containing algae or cyanobacteria was identified as potentially toxic AsSugars species. Negligible amounts of AB were detected. According to a tentative risk evaluation, the intake of Asi related to all FS collected was of no health concern for the general population. In 8 out of 33 of the analysed FS, however, the Asi concentration was of concern for population groups with increased cancer risks. If all As species except the non-toxic AB were taken into consideration, only 26 out of 33 of the FS showed 'no concern' for the general population, while for the other 7 FS a potential health risk was identified. This study indicates the need to obtain more data on toxicity of AsSugars and to develop limits for As (species) in FS.


Assuntos
Arsênio/análise , Cianobactérias/química , Suplementos Nutricionais/análise , Análise de Alimentos , Contaminação de Alimentos/análise , Phaeophyceae/química , Animais , Feminino , Humanos , Camundongos
5.
Artigo em Inglês | MEDLINE | ID: mdl-33300835

RESUMO

Clay products for oral use form a particular group of food supplements in relation to potential arsenic (As) toxicity, because - certainly in case of pure clay- all arsenic in these supplements is expected to be present in the most toxic inorganic form (Asi). In terms of risk, the most important questions to answer relate to the bioaccessibility and bioavailability of the inorganic arsenic present, rather than to the As species distribution, which often receives most attention in standard foodstuffs. In the present study, clay products for oral use were bought on the Belgian market and analysed for total arsenic (Astot), arsenic species (Asi, arsenobetaine, dimethylarsenate and monomethylarsenate)) and bioaccessible arsenic, in order to perform an exposure assessment and risk characterisation. Total As concentrations differed considerably between the samples and ranged from 0.20 to 6.4 mg Astot/kg. Bioaccessibility of Asi, determined via the Unified Barge Method (extraction making use of digestive enzymes) varied between 8% and 51%. The Asi concentration determined via HPLC-ICP-MS after extraction with diluted HNO3 + H2O2 (as in the CEN method for foodstuffs) was only a poor predictor of the bioaccessible Asi fraction, despite the significant relationship (R2 = 0.36; p < .05). The risk characterisation did not reveal acute risks related to Asi exposure. However, a potential concern with regard to chronic Asi intake was identified for the general population in 42% of the analysed food supplements, and for sensitive population groups in 67% of the samples, even after taking into account the bioaccessible fraction. The data presented illustrate that consumption of some of these clay products may contribute significantly to dietary Asi intake and that these should not be taken chronically.


Assuntos
Arsênio/administração & dosagem , Arsênio/análise , Argila/química , Análise de Alimentos , Contaminação de Alimentos/análise , Arsênio/metabolismo , Bélgica , Humanos , Medição de Risco
6.
Toxicol In Vitro ; 37: 121-133, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27633901

RESUMO

Endocrine activity of 65 compounds migrating from polycarbonate replacement plastic baby bottles was assessed using in vitro cell based assays (reporter gene assays) involving 7 nuclear receptors, i.e. human steroid hormones receptors (oestrogen, androgen, progesterone and glucocorticoid receptors), human thyroid beta and peroxisome proliferator-activated gamma receptors, and the mouse aryl hydrocarbon receptor. The chemicals were tested at 4 concentrations ranging from 0.001mM to 1mM. Only twelve chemicals did not show any activity towards any of the nuclear receptors, while fifty three compounds showed a possible endocrine activity. Most of the agonistic activities were observed towards the oestrogen receptor while the PPARγ was the target for most of the recorded antagonistic activities. Agonistic activities were recorded for several phthalates, benzophenones, aromatic hydrocarbons and phenols, while compounds such as benzaldehydes, ketones and esters of fatty acid showed antagonistic activities. Thirty five chemicals were able of agonistic activities on 1 to 4 receptors and antagonistic activities were recorded for 35 compounds as well, towards 1 to 7 receptors. Sixteen compounds were able of both agonistic and antagonistic activities, but not on the same receptors, except in 2 cases for the oestrogen receptor and 4 cases for the PPARγ.


Assuntos
Disruptores Endócrinos/farmacologia , Equipamentos para Lactente , Cimento de Policarboxilato/química , Receptores Citoplasmáticos e Nucleares/metabolismo , Animais , Bioensaio , Alimentação com Mamadeira , Linhagem Celular , Linhagem Celular Tumoral , Genes Reporter , Humanos , Camundongos , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Receptores Citoplasmáticos e Nucleares/genética
7.
Food Chem Toxicol ; 97: 108-119, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27591929

RESUMO

Since the European Commission prohibited the use of bisphenol A in the production of polycarbonate (PC) baby bottles, many other materials have replaced PC for the manufacture of this type of food contact materials. In the present study, the potential migration risks associated with these alternative materials were investigated. First, all substances were evaluated for endocrine disruptive (ED) activity by using different existing lists of (suspected) ED chemicals. Next, the potential non-ED risks were assessed. A distinction was made between migrants listed in Annex I of European Regulation 10/2011 and the unlisted substances (e.g. non-intentionally added substances). For the listed substances, concentrations in the migration solutions were compared to their respective specific migration limits (SML) (when applicable). Migration of all substances was shown to be below their SML. The unlisted substances were evaluated using toxicological information from previous evaluations, or if not available, by applying the Threshold of Toxicological Concern (TTC) approach. In case the estimated exposure to the unlisted substance exceeded the human exposure TTC value, a more indepth risk assessment was performed. Based on the results of both parts of the study, four baby bottles were considered of high concern because of the potential toxicity of migrating compounds.


Assuntos
Alimentação com Mamadeira/instrumentação , Disruptores Endócrinos/química , Contaminação de Alimentos/análise , Plastificantes/química , Plásticos/química , Cimento de Policarboxilato/química , Polímeros/química , Poluentes Ocupacionais do Ar/toxicidade , Compostos Benzidrílicos/toxicidade , Alimentação com Mamadeira/efeitos adversos , Disruptores Endócrinos/efeitos adversos , Disruptores Endócrinos/análise , Humanos , Lactente , Fenóis/toxicidade , Plastificantes/efeitos adversos , Plastificantes/análise , Medição de Risco
8.
Food Chem Toxicol ; 96: 107-16, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27481073

RESUMO

Reporter gene assays incorporating nuclear receptors (estrogen, androgen, thyroid ß and PPARγ2) have been implemented to assess the endocrine activity of 13 mycotoxins and their mixtures. As expected, zearalenone and its metabolites α-zearalenol and ß- zearalenol turned out to have the strongest estrogenic potency (EC50 8,7 10-10 ± 0,8; 3,1 10-11 ± 0,5 and 1,3 10-8 ± 0,3 M respectively). The metabolite of deoxynivalenol, 3-acetyl-deoxynivalenol also had estrogenic activity (EC50 3,8 10-7 ± 1,1 M). Furthermore, most of the mycotoxins (and their mixtures) showed anti-androgenic effects (15-acetyldeoxynivalenol, 3-acetyl-deoxynivalenol and α-zearalenol with potencies within one order of magnitude of that of the reference compound flutamide). In particular, deoxynivalenol and 15-acetyl-deoxynivalenol acted as antagonists for the PPARy2 receptor. When testing mixtures of mycotoxins on the same cell systems, we showed that most of the mixtures reacted as predicted by the concentration addition (CA) theory. Generally, the CA was within the 95% confidence interval of the observed ones, only minor deviations were detected. Although these reporter gene tests cannot be directly extrapolated in vivo, they can be the basis for further research. Especially the additive effects of ZEN and its metabolites are of importance and could have repercussions in vivo.


Assuntos
Neoplasias da Mama/patologia , Disruptores Endócrinos/toxicidade , Micotoxinas/toxicidade , Osteoblastos/citologia , Venenos/toxicidade , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Células Cultivadas , Disruptores Endócrinos/química , Feminino , Genes Reporter , Humanos , Luciferases/metabolismo , Micotoxinas/química , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , PPAR gama/metabolismo , Venenos/química , Receptores Androgênicos/metabolismo , Receptores de Estrogênio/metabolismo , Receptores dos Hormônios Tireóideos/metabolismo
9.
Food Chem Toxicol ; 89: 126-37, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26802677

RESUMO

Due to the worldwide concern that bisphenol A might act as an endocrine disruptor, alternative materials for polycarbonate (PC) have been introduced on the European market. However, PC-replacement products might also release substances of which the toxicological profile--including their genotoxic effects--has not yet been characterized. Because a thorough characterization of the genotoxic profile of all these substances is impossible in the short term, a strategy was developed in order to prioritize those substances for which additional data are urgently needed. The strategy consisted of a decision tree using hazard information related to genotoxicity. The relevant information was obtained from the database of the European Chemicals Agency (ECHA), in silico prediction tools (ToxTree and Derek Nexus(TM)) and the in vitro Vitotox(®) test for detecting DNA damage. By applying the decision tree, substances could be classified into different groups, each characterized by a different probability to induce genotoxic effects. Although none of the investigated substances could be unequivocally identified as genotoxic, the presence of genotoxic effects could neither be excluded for any of them. Consequently, all substances require more data to investigate the genotoxic potential. However, the type and the urge for these data differs among the substances.


Assuntos
Compostos Benzidrílicos/toxicidade , Mutagênicos/toxicidade , Fenóis/toxicidade , Cimento de Policarboxilato/química , Contaminação de Alimentos , Humanos , Lactente
10.
PLoS One ; 8(10): e77481, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24155963

RESUMO

Recently the environmental obesogen hypothesis has been formulated, proposing a role for endocrine disrupting compounds (EDCs) in the development of obesity. To evaluate this hypothesis, a screening system for obesogenic compounds is urgently needed. In this study, we suggest a standardised protocol for obesogen screening based on the 3T3-L1 cell line, a well-characterised adipogenesis model, and direct fluorescent measurement using Nile red lipid staining technique. In a first phase, we characterised the assay using the acknowledged obesogens rosiglitazone and tributyltin. Based on the obtained dose-response curves for these model compounds, a lipid accumulation threshold value was calculated to ensure the biological relevance and reliability of statistically significant effects. This threshold based method was combined with the well described strictly standardized mean difference (SSMD) method for classification of non-, weak- or strong obesogenic compounds. In the next step, a range of EDCs, used in personal and household care products (parabens, musks, phthalates and alkylphenol compounds), were tested to further evaluate the obesogenicity screening assay for its discriminative power and sensitivity. Additionally, the peroxisome proliferator activated receptor γ (PPARγ) dependency of the positive compounds was evaluated using PPARγ activation and antagonist experiments. Our results showed the adipogenic potential of all tested parabens, several musks and phthalate compounds and bisphenol A (BPA). PPARγ activation was associated with adipogenesis for parabens, phthalates and BPA, however not required for obesogenic effects induced by Tonalide, indicating the role of other obesogenic mechanisms for this compound.


Assuntos
Disruptores Endócrinos/efeitos adversos , Disruptores Endócrinos/análise , Obesidade/induzido quimicamente , PPAR gama/metabolismo , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Adipócitos/patologia , Animais , Diferenciação Celular/efeitos dos fármacos , Insulina/farmacologia , Camundongos , Obesidade/genética , PPAR gama/antagonistas & inibidores , PPAR gama/genética , Padrões de Referência , Coloração e Rotulagem , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/genética
11.
Int J Neuropsychopharmacol ; 16(5): 1153-63, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23177092

RESUMO

Oxytocin is a neuromodulator with antidepressant-like effects. In vitro, oxytocin is rapidly cleaved by insulin-regulated aminopeptidase (IRAP). Oxytocin metabolites are known to exert strong central activities that are different from the effects of the parent molecule. Our goal is to investigate in vivo whether IRAP deletion modifies the antidepressant-like effects of oxytocin. Male and female C57Bl/6 mice, IRAP wild-type (IRAP(+/+)) and knock-out (IRAP(-/-)) mice were injected subcutaneously with saline, oxytocin or oxytocin combined with angiotensin IV. One hour after injection, immobility was timed during a 5 min forced swim that was preceded by an open field to study locomotor behaviour. Oxytocin induced antidepressant-like effects in male (0.25 mg/kg oxytocin) and female (0.15 mg/kg oxytocin) C57Bl/6 mice subjected to the forced swim test. Oxytocin did not influence locomotor behaviour in mice, as shown with the open field. These findings were reproduced in transgenic male (aged 3-6 months) and female (aged 12-18 months) IRAP(+/+) mice. However, the major findings of our study were that the antidepressant-like effect was reversed in angiotensin IV treated IRAP(+/+) mice and was completely absent in age- and gender-matched IRAP(-/-) mice. The lack of an antidepressant-like effect of oxytocin in young male and middle-aged female IRAP(-/-) mice attributes an important role to IRAP in mediating this effect.


Assuntos
Aminopeptidases/metabolismo , Antidepressivos/uso terapêutico , Depressão/tratamento farmacológico , Ocitocina/uso terapêutico , Fatores Etários , Angiotensina II/análogos & derivados , Angiotensina II/farmacologia , Animais , Antidepressivos/farmacologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/enzimologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Cistinil Aminopeptidase/deficiência , Cistinil Aminopeptidase/genética , Depressão/sangue , Depressão/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Comportamento Exploratório/efeitos dos fármacos , Feminino , Imipramina/uso terapêutico , Resposta de Imobilidade Tônica/efeitos dos fármacos , Insulina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Atividade Motora/efeitos dos fármacos , Ocitocina/sangue , Ocitocina/farmacologia
12.
Fundam Clin Pharmacol ; 26(2): 194-7, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21477268

RESUMO

Radioligand binding studies revealed that Ang IV binds to insulin-regulated aminopeptidase (IRAP)/'AT(4) receptors' with high affinity. Yet, as these experiments were routinely carried out in the presence of chelators, only the catalytic zinc-depleted apo-form of IRAP was labelled. While the chelators remove the catalytic zinc from IRAP and protect Ang IV from proteolytic degradation, the aminopeptidase N selective inhibitor '7B' only exerts the latter effect. By using 7B along with the new stable Ang IV-analog [(3) H]AL-11, we here show that the native enzyme is only a low-affinity target for Ang IV.


Assuntos
Angiotensina II/análogos & derivados , Quelantes/farmacologia , Cistinil Aminopeptidase/metabolismo , Compostos Organofosforados/farmacologia , Tirosina/análogos & derivados , Angiotensina II/metabolismo , Animais , Antígenos CD13/antagonistas & inibidores , Antígenos CD13/metabolismo , Células CHO , Linhagem Celular , Cricetinae , Cricetulus , Camundongos , Ensaio Radioligante , Tirosina/farmacologia , Zinco/química
13.
J Pept Sci ; 17(8): 545-53, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21538707

RESUMO

The aromatic amino acids Tyr and Phe in angiotensin IV (Ang IV) were conformationally constrained by the use of ß-Me substituted analogs, or cyclic constrained analogs. None of these modifications was allowed for Tyr¹, while only e-ß-MePhe6 substitution resulted in an AngIV analog with high IRAP potency and selectivity versus AP-N or the AT1 receptor. This indicates an important role of the orientation of the Phe6 for inducing selectivity. Pro5 replacement with 2-aminocyclopentanecarboxylic acid maintained IRAP potency and abolished AT1 affinity. These results confirm the importance of conformational constrained amino acids to generate selectivity in bioactive peptides.


Assuntos
Angiotensina II/análogos & derivados , Fenilalanina/metabolismo , Prolina/metabolismo , Tirosina/metabolismo , Aminopeptidases/metabolismo , Angiotensina II/química , Angiotensina II/metabolismo , Animais , Biocatálise , Células CHO , Membrana Celular/metabolismo , Células Cultivadas , Cricetinae , Cricetulus , Células HEK293 , Humanos , Estrutura Molecular , Fenilalanina/análogos & derivados , Fenilalanina/química , Prolina/análogos & derivados , Prolina/química , Conformação Proteica , Espectrofotometria Atômica , Especificidade por Substrato , Tirosina/análogos & derivados , Tirosina/química
14.
Mol Cell Endocrinol ; 339(1-2): 34-44, 2011 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-21457753

RESUMO

Insulin regulated aminopeptidase (IRAP) recognises "AT(4)-receptor" ligands like angiotensin IV (Ang IV) and peptidomimetics like AL-11. The metabolic stability and high affinity of [(3)H]AL-11 for catalytically active IRAP allowed its detection in Chinese hamster ovary (CHO-K1) cell membranes in the absence of chelators (Demaegdt et al., 2009). Here, we show that, contrary to [(3)H]Ang IV, [(3)H]AL-11 displays high affinity and specificity for IRAP in intact CHO-K1 cells as well. After binding to IRAP at the surface, [(3)H]AL-11 is effectively internalized by an endocytotic process. Unexpectedly, surface binding and internalization of [(3)H]AL-11 was not affected by pretreating the cells with Ang IV but declined with AL-11. In the latter case surface expression of IRAP even increased. After elimination of simpler explanations, it is proposed that metabolically stable "AT(4)-receptor" ligands undergo semi-continuous cycling between the cell surface and endosomal compartments. The in vivo efficacy of stable and unstable "AT(4)-receptor" ligands could therefore differ.


Assuntos
Angiotensina II/análogos & derivados , Cistinil Aminopeptidase/metabolismo , Peptidomiméticos/farmacologia , Angiotensina II/farmacologia , Animais , Ligação Competitiva , Células CHO , Cricetinae , Cricetulus , Células HEK293 , Hemoglobinas/farmacologia , Humanos , Ligantes , Fragmentos de Peptídeos/farmacologia , Ligação Proteica , Transporte Proteico , Ensaio Radioligante
15.
J Med Chem ; 54(11): 3779-92, 2011 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-21476495

RESUMO

Macrocyclic analogues of angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) targeting the insulin-regulated aminopeptidase (IRAP) have been designed, synthesized, and evaluated biologically. Replacement of His(4)-Pro(5)-Phe(6) by a 2-(aminomethyl)phenylacetic acid (AMPAA) moiety and of Val(1) and Ile(3) by amino acids bearing olefinic side chains followed by macrocyclization provided potent IRAP inhibitors. The impact of the ring size and the type (saturated versus unsaturated), configuration, and position of the carbon-carbon bridge was assessed. The ring size generally affects the potency more than the carbon-carbon bond characteristics. Replacing Tyr(2) by ß(3)hTyr or Phe is accepted, while N-methylation of Tyr(2) is deleterious for activity. Removal of the carboxyl group in the C-terminal slightly reduced the potency. Inhibitors 7 (K(i) = 4.1 nM) and 19 (K(i) = 1.8 nM), both encompassing 14-membered ring systems connected to AMPAA, are 10-fold more potent than Ang IV and are also more selective over aminopeptidase N (AP-N). Both compounds displayed high stability against proteolysis by metallopeptidases.


Assuntos
Cistinil Aminopeptidase/antagonistas & inibidores , Desenho de Fármacos , Lactamas/síntese química , Lactamas/farmacologia , Nootrópicos/síntese química , Nootrópicos/farmacologia , Fenilacetatos/síntese química , Fenilacetatos/farmacologia , Inibidores de Proteases/síntese química , Inibidores de Proteases/farmacologia , Alcenos/química , Angiotensina II/análogos & derivados , Angiotensina II/química , Animais , Células CHO , Cricetinae , Cricetulus , Cistinil Aminopeptidase/metabolismo , Estabilidade de Medicamentos , Lactamas/química , Nootrópicos/química , Fenilacetatos/química , Inibidores de Proteases/química , Relação Estrutura-Atividade
16.
Hypertension ; 57(5): 956-64, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21464395

RESUMO

Recently, a new derivative of angiotensin (Ang) II, called "Ang A," has been discovered to be present in plasma of healthy humans and, in increased concentrations, in end-stage renal failure patients. The objectives of the study were to investigate the blood pressure and renal hemodynamic responses to Ang A in normotensive and hypertensive rats and in genetically modified mice and the binding properties of Ang A to Ang II type 1 (AT(1)) or Ang II type 2 (AT(2)) receptors. Intravenous and intrarenal administration of Ang A induced dose-dependent pressor and renal vasoconstrictor responses in normotensive rats, which were blocked by the AT(1) receptor antagonist candesartan but were not altered by the AT(2) receptor ligands PD123319, CGP42112A, or compound 21. Similar responses were observed after intravenous administration in spontaneously hypertensive rats. Deletion of AT(1a) receptors in mice almost completely abolished the pressor and renal vasoconstrictor responses to Ang A, indicating that its effects are mediated via AT(1a) receptors. Ang A was less potent than Ang II in vivo. The in vitro study demonstrated that Ang A is a full agonist for AT(1) receptors, with similar affinity for AT(1) and AT(2) receptors as Ang II. Overall, the responses to Ang A and Ang II were similar. Ang A has no physiological role to modulate the pressor and renal hemodynamic effects of Ang II.


Assuntos
Angiotensinas/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Receptor Tipo 1 de Angiotensina/metabolismo , Circulação Renal/efeitos dos fármacos , Vasoconstrição/efeitos dos fármacos , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Angiotensinas/metabolismo , Animais , Benzimidazóis/farmacologia , Compostos de Bifenilo , Pressão Sanguínea/fisiologia , Relação Dose-Resposta a Droga , Hipertensão/metabolismo , Rim/efeitos dos fármacos , Rim/metabolismo , Masculino , Camundongos , Camundongos Knockout , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Receptor Tipo 1 de Angiotensina/genética , Circulação Renal/fisiologia , Estatísticas não Paramétricas , Tetrazóis/farmacologia , Vasoconstrição/fisiologia
17.
J Med Chem ; 53(22): 8059-71, 2010 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-21047126

RESUMO

The insulin-regulated aminopeptidase (IRAP) localized in areas of the brain associated with memory and learning is emerging as a new promising therapeutic target for the treatment of memory dysfunctions. The angiotensin II metabolite angiotensin IV (Ang IV, Val(1)-Tyr(2)-Ile(3)-His(4)-Pro(5)-Phe(6)) binds with high affinity to IRAP and inhibits this aminopeptidase (K(i) = 62.4 nM). Furthermore, Ang IV has been demonstrated to enhance cognition in animal models and is believed to play an important role in cognitive processes. It is herein reported that displacement of the C-terminal tripeptide His(4)-Pro(5)-Phe(6) with a phenylacetic acid functionality combined with a constrained macrocyclic system in the N-terminal affords potent IRAP inhibitors that are less peptidic in character than the hexapeptide Ang IV. Configurational analysis of three pairs of diastereomeric Ang IV analogues was performed using a combination of solution NMR spectroscopic methods, Monte Carlo conformational searches, and NAMFIS calculations. The compounds encompassing l-amino acids only (4, 8, and 12) showed significantly higher bioactivity compared to their lld-epimers (5, 9, and 13). The best inhibitors in the series, compounds 8 and 12, incorporating a 13- and 14-membered disulfide ring system, respectively, and both with a ß(3)-homotyrosine residue (ß(3)hTyr) replacing Tyr(2), exhibit K(i) values of 3.3 and 5.2 nM, respectively.


Assuntos
Angiotensina II/análogos & derivados , Cistinil Aminopeptidase/antagonistas & inibidores , Dissulfetos/síntese química , Oligopeptídeos/síntese química , Peptídeos Cíclicos/síntese química , Angiotensina II/síntese química , Angiotensina II/química , Angiotensina II/farmacologia , Animais , Linhagem Celular , Cricetinae , Cricetulus , Dissulfetos/química , Dissulfetos/farmacologia , Humanos , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular , Método de Monte Carlo , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Peptídeos Cíclicos/química , Peptídeos Cíclicos/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade
18.
J Neurochem ; 112(5): 1223-34, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20028450

RESUMO

Intracerebroventricular (i.c.v.) administration of angiotensin IV (Ang IV) or Leu-Val-Val-haemorphin 7 (LVV-H7) improves memory performance in normal rats and reverses memory deficits in rat models for cognitive impairment. These memory effects were believed to be mediated via the putative 'AT4 receptor'. However, this binding site was identified as insulin-regulated aminopeptidase (IRAP). Correspondingly, Ang IV and LVV-H7 were characterised as IRAP inhibitors. This study investigates whether and how IRAP may be involved in the central effects of Ang IV and LVV-H7. We determined the effects of i.c.v. administration of Ang IV or LVV-H7 on hippocampal neurotransmitter levels using microdialysis in rats. We observed that Ang IV modulates hippocampal acetylcholine levels, whereas LVV-H7 does not. This discrepancy was reflected in the observation that Ang IV binds with micromolar affinity to the AT1 receptor whereas no binding affinity was observed for LVV-H7. Correspondingly, we demonstrated that the AT1 receptor is involved in the effects of Ang IV on hippocampal neurotransmitter levels and on spatial working memory in a plus maze spontaneous alternation task. However, the AT1 receptor was not involved in the spatial memory facilitating effect of LVV-H7. Finally, we demonstrated that Ang IV did not diffuse to the hippocampus following i.c.v. injection, suggesting an extrahippocampal site of action. We propose that AT1 receptors are implicated in the neurochemical and cognitive effects of Ang IV, whereas LVV-H7 may mediate its effects via IRAP.


Assuntos
Angiotensina II/análogos & derivados , Hemoglobinas/administração & dosagem , Hipocampo/efeitos dos fármacos , Memória de Curto Prazo/efeitos dos fármacos , Neurotransmissores/metabolismo , Fragmentos de Peptídeos/administração & dosagem , Receptor Tipo 1 de Angiotensina/fisiologia , Angiotensina II/administração & dosagem , Angiotensina II/farmacocinética , Animais , Relação Dose-Resposta a Droga , Hipocampo/diagnóstico por imagem , Hipocampo/metabolismo , Injeções Intraventriculares/métodos , Isótopos de Iodo/farmacocinética , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Microdiálise/métodos , Ligação Proteica/efeitos dos fármacos , Ratos , Ratos Wistar , Percepção Espacial/efeitos dos fármacos , Distribuição Tecidual/efeitos dos fármacos , Tomografia Computadorizada de Emissão de Fóton Único/métodos
19.
J Med Chem ; 52(18): 5612-8, 2009 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-19757839

RESUMO

The histidine residue in angiotensin IV was replaced by various conformationally constrained amino acids. The substitution of the His(4)-Pro(5) dipeptide sequence by the constrained Trp analogue Aia-Gly, in combination with beta(2)hVal substitution at the N-terminus, provided a new stable analogue H-(R)-beta(2)hVal-Tyr-Ile-Aia-Gly-Phe-OH (AL-40) that is a potent ligand for the Ang IV receptor IRAP and selective versus AP-N and the AT1 receptor.


Assuntos
Angiotensina II/análogos & derivados , Histidina , Sequência de Aminoácidos , Aminopeptidases/metabolismo , Angiotensina II/química , Angiotensina II/metabolismo , Animais , Azepinas/química , Biomimética , Células CHO , Ácidos Carboxílicos/química , Cricetinae , Cricetulus , Cistinil Aminopeptidase/metabolismo , Humanos , Fenilalanina/química , Conformação Proteica , Receptor Tipo 1 de Angiotensina/metabolismo , Especificidade por Substrato
20.
Mol Cell Endocrinol ; 311(1-2): 77-86, 2009 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-19643163

RESUMO

'AT(4) receptors' through which Angiotensin IV (Ang IV) improves memory acquisition, were recently identified as insulin regulated aminopeptidase (IRAP). Radioligand binding studies have hitherto been performed with iodinated Ang IV in the presence of divalent cation chelators EDTA and 1,10-phenanthrolin. Hence, they referred to the apo-form of IRAP. Presently, binding of [(3)H]Ang IV and [(3)H]AL-11, a stable Ang IV analog, was compared on Chinese hamster ovary (CHO-K1) and mouse hippocampal (P40H1) cell membranes. With chelators, their high affinity sites showed the same pharmacological profile as for [(125)I]Ang IV binding. Without chelators, only high affinity binding was perceived for [(3)H]AL-11. The same pharmacological profile was recorded in both membrane preparations; it was different from the one in the presence of chelators and corresponded to catalytically active IRAP (despite the concurrent presence of aminopeptidase N (APN) in P40H1 cell membranes). This confirms that the active and apo-forms of IRAP have a distinct pharmacological profile.


Assuntos
Angiotensina II/análogos & derivados , Cistinil Aminopeptidase/metabolismo , Receptores de Angiotensina/metabolismo , Coloração e Rotulagem , Angiotensina II/metabolismo , Animais , Ligação Competitiva , Bioensaio , Células CHO , Cricetinae , Cricetulus , Cistinil Aminopeptidase/antagonistas & inibidores , Humanos , Cinética , Ligantes , Camundongos , Trítio
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