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1.
mBio ; 11(3)2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32371599

RESUMO

The vaginal microbiota influences sexual transmission of human immunodeficiency virus type 1 (HIV-1). Colonization of the vaginal tract is normally dominated by Lactobacillus species. Both Lactobacillus and Enterococcus faecalis may secrete reutericyclin, which inhibits the growth of a variety of pathogenic bacteria. Increasing evidence suggests a potential therapeutic role for an analogue of reutericyclin, glycerol monolaurate (GML), against microbial pathogens. Previous studies using a macaque vaginal simian immunodeficiency virus (SIV) transmission model demonstrated that GML reduces transmission and alters immune responses to infection in vitro Previous studies showed that structural analogues of GML negatively impact other enveloped viruses. We sought to expand understanding of how GML inhibits HIV-1 and other enveloped viruses and show that GML restricts HIV-1 entry post-CD4 engagement at the step of coreceptor binding. Further, HIV-1 and yellow fever virus (YFV) particles were more sensitive to GML interference than particles "matured" by proteolytic processing. We show that high-pressure-liquid-chromatography (HPLC)-purified reutericyclin and reutericyclin secreted by Lactobacillus inhibit HIV-1. These data emphasize the importance and protective nature of the normal vaginal flora during viral infections and provide insights into the antiviral mechanism of GML during HIV-1 infection and, more broadly, to other enveloped viruses.IMPORTANCE A total of 340 million sexually transmitted infections (STIs) are acquired each year. Antimicrobial agents that target multiple infectious pathogens are ideal candidates to reduce the number of newly acquired STIs. The antimicrobial and immunoregulatory properties of GML make it an excellent candidate to fit this critical need. Previous studies established the safety profile and antibacterial activity of GML against both Gram-positive and Gram-negative bacteria. GML protected against high-dose SIV infection and reduced inflammation, which can exacerbate disease, during infection. We found that GML inhibits HIV-1 and other human-pathogenic viruses (yellow fever virus, mumps virus, and Zika virus), broadening its antimicrobial range. Because GML targets diverse infectious pathogens, GML may be an effective agent against the broad range of sexually transmitted pathogens. Further, our data show that reutericyclin, a GML analog expressed by some lactobacillus species, also inhibits HIV-1 replication and thus may contribute to the protective effect of Lactobacillus in HIV-1 transmission.


Assuntos
Antivirais/farmacologia , Lactobacillus/metabolismo , Lauratos/farmacologia , Monoglicerídeos/farmacologia , Proteínas do Envelope Viral/metabolismo , Vírus/efeitos dos fármacos , Animais , Antivirais/metabolismo , Feminino , HIV-1/efeitos dos fármacos , HIV-1/metabolismo , HIV-1/fisiologia , Humanos , Lauratos/metabolismo , Monoglicerídeos/metabolismo , Receptores Virais/metabolismo , Ácido Tenuazônico/análogos & derivados , Ácido Tenuazônico/metabolismo , Ácido Tenuazônico/farmacologia , Vagina/microbiologia , Ligação Viral , Internalização do Vírus , Vírus/metabolismo
3.
Sci Rep ; 9(1): 14550, 2019 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601928

RESUMO

Human milk has antimicrobial compounds and immunomodulatory activities. We investigated glycerol monolaurate (GML) in human milk versus bovine milk and infant formula for antimicrobial and anti-inflammatory activities. Human milk contained approximately 3000 µg/ml of GML, compared to 150 µg/ml in bovine milk and none in infant formula. For bacteria tested (Staphylococcus aureus, Bacillus subtilis, Clostridium perfringens, Escherichia coli), except Enterococcus faecalis, human milk was more antimicrobial than bovine milk and formula. The Enterococcus faecalis strain, which was not inhibited, produced reutericyclin, which is an analogue of GML and functions as a growth stimulant in bacteria that produce it. Removal of GML and other lipophilic molecules from human milk by ethanol extraction resulted in a loss of antibacterial activity, which was restored by re-addition of GML. GML addition caused bovine milk to become antimicrobial. Human milk but not bovine milk or formula inhibited superantigen and bacterial-induced IL-8 production by model human epithelial cells. GML may contribute beneficially to human milk compared to bovine milk or infant formula.


Assuntos
Antibacterianos/farmacologia , Anti-Inflamatórios/farmacologia , Lauratos/farmacologia , Leite Humano/química , Monoglicerídeos/farmacologia , Animais , Bacillus subtilis/efeitos dos fármacos , Bovinos , Clostridium perfringens/efeitos dos fármacos , Enterococcus faecalis/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Humanos , Inflamação , Testes de Sensibilidade Microbiana , Staphylococcus aureus/efeitos dos fármacos , Ácido Tenuazônico/análogos & derivados , Ácido Tenuazônico/metabolismo
4.
J Appl Microbiol ; 126(1): 177-190, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30216614

RESUMO

AIM: To observe the variation in accumulation of Fusarium and Alternaria mycotoxins across a topographically heterogeneous field and tested biotic (fungal and bacterial abundance) and abiotic (microclimate) parameters as explanatory variables. METHODS AND RESULTS: We selected a wheat field characterized by a diversified topography, to be responsible for variations in productivity and in canopy-driven microclimate. Fusarium and Alternaria mycotoxins where quantified in wheat ears at three sampling dates between flowering and harvest at 40 points. Tenuazonic acid (TeA), alternariol (AOH), alternariol monomethyl ether (AME), tentoxin (TEN), deoxynivalenol (DON), zearalenone (ZEN) and deoxynivalenol-3-Glucoside (DON.3G) were quantified. In canopy temperature, air and soil humidity were recorded for each point with data-loggers. Fusarium spp. as trichothecene producers, Alternaria spp. and fungal abundances were assessed using qPCR. Pseudomonas fluorescens bacteria were quantified with a culture based method. We only found DON, DON.3G, TeA and TEN to be ubiquitous across the whole field, while AME, AOH and ZEN were only occasionally detected. Fusarium was more abundant in spots with high soil humidity, while Alternaria in warmer and drier spots. Mycotoxins correlated differently to the observed explanatory variables: positive correlations between DON accumulation, tri 5 gene and Fusarium abundance were clearly detected. The correlations among the others observed variables, such as microclimatic conditions, varied among the sampling dates. The results of statistical model identification do not exclude that species coexistence could influence mycotoxin production. CONCLUSIONS: Fusarium and Alternaria mycotoxins accumulation varies heavily across the field and the sampling dates, providing the realism of landscape-scale studies. Mycotoxin concentrations appear to be partially explained by biotic and abiotic variables. SIGNIFICANCE AND IMPACT OF THE STUDY: We provide a useful experimental design and useful data for understanding the dynamics of mycotoxin biosynthesis in wheat.


Assuntos
Contaminação de Alimentos/análise , Micotoxinas/química , Triticum/química , Alternaria/genética , Alternaria/crescimento & desenvolvimento , Alternaria/metabolismo , Fusarium/genética , Fusarium/crescimento & desenvolvimento , Fusarium/metabolismo , Glucosídeos/análise , Glucosídeos/metabolismo , Lactonas/análise , Lactonas/metabolismo , Microclima , Micotoxinas/metabolismo , Pseudomonas fluorescens/química , Pseudomonas fluorescens/genética , Pseudomonas fluorescens/crescimento & desenvolvimento , Pseudomonas fluorescens/metabolismo , Metabolismo Secundário , Microbiologia do Solo , Ácido Tenuazônico/análise , Ácido Tenuazônico/metabolismo , Tricotecenos/análise , Tricotecenos/metabolismo , Triticum/microbiologia , Zearalenona/análise , Zearalenona/metabolismo
5.
Toxicol Lett ; 301: 168-178, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30321595

RESUMO

Alternaria mycotoxins frequently contaminate agricultural crops and may impact animal and human health. However, data on mammalian metabolism and potential biomarkers of exposure for human biomonitoring (HBM) are scarce. Here, we report the preliminary investigation with respect to metabolism and excretion of Alternaria toxins in Sprague Dawley rats. Four animals were housed in metabolic cages for 24 h after gavage administration of an Alternaria alternata culture extract containing ten known toxins. LC-MS/MS analysis of 17 Alternaria toxins in urine and fecal samples allowed to gain first insights regarding xenobiotic metabolism and excretion rates. Alternariol (6-10%), alternariol monomethyl ether (AME, 6-7%) and tenuazonic acid (up to 55%) were recovered in urine and fecal samples (9%, 87%, 0.3%, respectively), while perylene quinones administered at comparatively high levels, were either determined at very low levels (up to 0.5% altertoxin I in urine and 15% in feces; 0.2% alterperylenol in urine and 3% in feces) or not at all (altertoxin II, stemphyltoxin III). AME-3-sulfate, which was not present in the administered extract, was determined in urine, representing up to 23% of the AME intake. Critical evaluation of the applied sample preparation protocol and LC-MS/MS analysis revealed interesting preliminary results and information crucial for improving follow-up experiments.


Assuntos
Alternaria , Micotoxinas/metabolismo , Animais , Benzo(a)Antracenos/metabolismo , Benzo(a)Antracenos/urina , Cromatografia Líquida , Fezes/química , Lactonas/metabolismo , Lactonas/urina , Limite de Detecção , Masculino , Micotoxinas/urina , Perileno/análogos & derivados , Perileno/metabolismo , Perileno/urina , Ratos , Ratos Sprague-Dawley , Espectrometria de Massas em Tandem , Ácido Tenuazônico/metabolismo , Ácido Tenuazônico/urina
6.
Sci Total Environ ; 640-641: 1132-1138, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30021278

RESUMO

Sorghum is the fifth most cultivated and consumed grain in the world. However, this grain is frequently contaminated with toxins from fungi. The present study evaluated the effects of environmental factors on tenuazonic acid (TeA) production by Epicoccum sorghinum in the field and in controlled laboratory conditions. In this study, 50 sorghum grain samples were collected from summer and autumn growing seasons and analyzed for TeA contamination using LC-MS/MS. To further understand the ecophysiology of this fungus, an isolated strain of E. sorghinum from the field was investigated for its development and TeA production under controlled environmental conditions in the laboratory. In the ecophysiological investigation, the effects of water activity (0.90, 0.95, 0.99) and temperature (18, 22, 26 and 30 °C) were evaluated on the radial growth, enzymatic production and expression of TAS1, which is the gene involved in TeA production. Results showed that in the field, the summer season presented the highest TeA average level in the grains (587.8 µg/kg) compared to level found in the autumn (440.5 µg/kg). The ecophysiological investigation confirmed that E. sorghinum produces more actively TeA under environmental conditions simulating the summer season. Optimum growth, maximum TAS1 gene expression, and higher extracellular enzymatic production were observed at 26 °C with a water activity of 0.99. Pearson correlation analyses showed that the production of TeA highly correlates with fungal growth. The present study demonstrates that abiotic factors in a combined approach of field and laboratory conditions will assist in predicting the driving environmental factors that could affect growth of E. sorghinum and TeA production in sorghum grains.


Assuntos
Ascomicetos/fisiologia , Ácido Tenuazônico/metabolismo , Alternaria , Micotoxinas , Sorghum
7.
ACS Chem Biol ; 12(9): 2270-2274, 2017 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-28820236

RESUMO

Tenuazonic acid (TeA) is a mycotoxin produced by the rice blast fungus Pyricularia oryzae and some plant pathogenic fungi. We previously demonstrated that TeA is biosynthesized in P. oryzae by TeA synthetase 1 (TAS1) and that its production is induced by osmo-sensory MAPK-encoding gene (OSM1) deletion or the addition of 1% DMSO to cultures; however, the regulatory mechanisms of TeA production were unknown. Here, we identify a Zn(II)2-Cys6-type transcription factor in the upstream region of TAS1, which is encoded by TAS2 and regulates TeA production. We also find PoLAE1, which is a homologue of LaeA, a regulator of fungal secondary metabolism. Analysis of PoLAE1 deletion and overexpression strains indicate that PoLAE1 drives TeA production. We also demonstrate that two TeA-inducing signals, 1% DMSO addition and OSM1 deletion, were transmitted through PoLAE1. Our results indicate that TeA production is regulated by two specific regulators, TAS2 and PoLAE1, in P. oryzae.


Assuntos
Ascomicetos/metabolismo , Vias Biossintéticas , Proteínas Fúngicas/metabolismo , Micotoxinas/metabolismo , Ácido Tenuazônico/metabolismo , Oryza/microbiologia , Fatores de Transcrição/metabolismo
8.
Plant Physiol Biochem ; 115: 73-82, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28324684

RESUMO

A toxin-deficient mutant strain, HP001 mutant of Alternaria alternata, whose mycelium is unable to infect its host, produces little tenuazonic acid (TeA) toxin. How TeA plays a role in initiating host infection by A. alternata remains unclear. In this research we use Imaging-PAM based on chlorophyll fluorescence parameters and transmission electron microscopy to explore the role of TeA toxin during the infection process of A. alternata. Photosystem II damage began even before wild type mycelium infected the leaves of its host, croftonweed (Ageratina adenophora). Compared with the wild type, HP001 mutant produces morphologically different colonies, hyphae with thinner cell walls, has higher reactive oxygen species (ROS) content and lower peroxidase activity, and fails to form appressoria on the host surface. Adding TeA toxin allows the mutant to partially recover these characters and more closely resemble the wild type. Additionally, we found that the mutant is able to elicit disease symptoms when its mycelium is placed on leaves whose epidermis has been manually removed, which indicates that TeA may be determinant in the fungus recognition of its plant host. Lack of TeA toxin appears responsible for the loss of pathogenicity of the HP001 mutant. As a key virulence factor, TeA toxin not only damages the host plant but also is involved in maintaining ROS content, host recognition, inducing appressoria to infect the host and for allowing completion of the infection process.


Assuntos
Ageratina/metabolismo , Alternaria/metabolismo , Ácido Tenuazônico/toxicidade , Fatores de Virulência/toxicidade , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Doenças das Plantas , Folhas de Planta/microbiologia , Ácido Tenuazônico/metabolismo , Fatores de Virulência/metabolismo
9.
Bioorg Med Chem Lett ; 26(24): 5843-5850, 2016 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-27865702

RESUMO

The diversity of natural products is greater than that of combinatorial chemistry compounds and is similar to that of drugs. Compounds rich in sp3 carbons, such as natural products, typically exhibit high structural complexity and high specificity to molecular targets. Microorganisms can synthesize such sp3 carbon-rich compounds and can be used as excellent factories for making bioactive compounds. Here, we mainly focus on pathway engineering of two sp3 carbon-rich bioactive indole alkaloids, fumitremorgin C and terpendole E. We also demonstrate the importance of activation of secondary metabolism by focusing on tenuazonic acid, a bioactive tetramic acid compound, as an example.


Assuntos
Produtos Biológicos/metabolismo , Diterpenos/metabolismo , Fungos/metabolismo , Alcaloides Indólicos/metabolismo , Indóis/metabolismo , Ácido Tenuazônico/metabolismo , Produtos Biológicos/química , Diterpenos/química , Alcaloides Indólicos/química , Indóis/química , Estrutura Molecular , Metabolismo Secundário , Ácido Tenuazônico/química
10.
Int J Food Microbiol ; 236: 155-60, 2016 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-27517345

RESUMO

Sweet pepper (Capsicum annuum) is an important crop cultivated worldwide, with Argentina being one of the major producers in South America. The fruit is susceptible to several fungal diseases, leading to severe economic losses for producers. In this study, Alternaria was found as the prevalent genus in mouldy peppers (50% fruits infected). Morphological identification revealed that all 64 Alternaria isolates belonged to small-spored species, most of them corresponding to A. tenuissima, A. arborescens and A. alternata species-groups. Their secondary metabolite profile was evaluated in vitro; alternariols were synthesized by most of the isolates (91% for alternariol and 92% for alternariol monomethyl ether). A high number of Alternaria spp. also produced tenuazonic acid (64%), altenuene (84%) and tentoxin (72%). In addition, damaged pepper fruits were analysed for the presence of tenuazonic acid and alternariols. A total 32 out of 48 spoiled pepper fruits were contaminated with at least one of these metabolites. Half of the samples were positive for tenuazonic acid (range 8-11,422µg/kg), while alternariol and its monomethyl ether were less frequently detected (21 and 29%, respectively) and at lower concentrations. This is the first report on the natural occurrence of Alternaria mycotoxins in Argentinean sweet pepper, and highlights a consumer risk when mouldy fruits are used in industrialized products because these compounds are not destroyed by conventional heat treatments.


Assuntos
Alternaria/isolamento & purificação , Micotoxinas/análise , Piper nigrum/microbiologia , Verduras/microbiologia , Alternaria/classificação , Alternaria/genética , Argentina , Contaminação de Alimentos/análise , Frutas/microbiologia , Lactonas/metabolismo , Micotoxinas/metabolismo , América do Sul , Ácido Tenuazônico/metabolismo , Verduras/química
11.
Int J Food Microbiol ; 219: 44-9, 2016 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-26708802

RESUMO

Alternaria arborescens has been reported as a common fungal species invading tomatoes and is capable of producing several mycotoxins in infected plants, fruits and in agricultural commodities. Alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA) are some of the main Alternaria mycotoxins that can be found as contaminants of food. This species can produce these toxic metabolites together with AAL toxins (Alternaria alternata f. sp. lycopersicum toxins), which can act as inhibitors of sphingolipid biosynthesis. The objective of this study was to determine the effect of water activity (aw, 0.995, 0.975, 0.950) and temperature (6, 15, 20, 25 and 30 °C) on mycotoxin production by A. arborescens on a synthetic tomato medium. The optimum production of AOH and AME occurred at 0.975 aw after 40 days of incubation at 30 °C. The maximum TeA accumulation was observed at 0.975 aw and 25 °C and at 0.950 aw and 30 °C. AAL TA was produced in higher quantities at 0.995 aw and 30 °C. At 6 °C no quantifiable levels of AOH or AME were detected, but significant amounts of TeA were produced at 0.975 aw. In general, high aw levels and high temperatures were favorable for mycotoxin production. The greatest accumulation of all four toxins occurred at 0.975 aw and 30 °C. The results obtained here could be extrapolated to evaluate the risk of tomato fruits and tomato products contamination caused by these toxins.


Assuntos
Alternaria/metabolismo , Lycopersicon esculentum/microbiologia , Micotoxinas/metabolismo , Temperatura , Água/metabolismo , Alternaria/patogenicidade , Contaminação de Alimentos , Microbiologia de Alimentos , Frutas/química , Lactonas/metabolismo , Micotoxinas/análise , Esfingolipídeos/biossíntese , Ácido Tenuazônico/metabolismo
12.
J Agric Food Chem ; 63(38): 8560-7, 2015 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-26371380

RESUMO

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantitate tenuazonic acid (TeA) in pig and broiler chicken plasma was successfully developed and validated. Linear matrix-matched calibration curves ranged between 5 and 200 ng/mL. Correlation coefficients, goodness-of-fit coefficients, and within-day and between-day precision and accuracy fell well within the acceptance criteria. The limit of quantitation was 5.0 ng/mL in both pig and broiler chicken plasma. The LC-MS/MS method was applied in a comparative toxicokinetic study in both pigs and broiler chickens. TeA was completely bioavailable after oral administration in both animal species. However, absorption was deemed to be slower in broiler chickens (mean tmax 0.32 h in pigs vs 2.60 h in chickens). TeA was more slowly eliminated in broiler chickens (mean t1/2el 0.55 h in pigs vs 2.45 h in chickens after oral administration), mainly due to the significantly lower total body clearance (mean Cl 446.1 mL/h/kg in pigs vs 59.2 mL/h/kg in chickens after oral administration). Tissue residue studies and further research to elucidate the biotransformation and excretion processes of TeA in pigs, broiler chickens, and other animal species are imperative.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Micotoxinas/sangue , Micotoxinas/toxicidade , Espectrometria de Massas em Tandem/métodos , Ácido Tenuazônico/sangue , Ácido Tenuazônico/toxicidade , Animais , Galinhas , Micotoxinas/metabolismo , Suínos , Ácido Tenuazônico/metabolismo , Toxicocinética
13.
Rev. iberoam. micol ; 31(2): 119-124, abr.-jun. 2014.
Artigo em Espanhol | IBECS | ID: ibc-121252

RESUMO

Antecedentes. Muchas especies de Alternaria han sido estudiadas por su capacidad de producir metabolitos secundarios bioactivos como la tentoxina (TEN), algunos de los cuales tienen propiedades tóxicas. Las principales toxinas de Alternaria contaminantes de alimentos son el ácido tenuazónico, el alternariol (AOH), el alternariol monometil éter (AME), el altenueno y las altertoxinas i , ii y iii . Objetivos. Determinar los perfiles de metabolitos secundarios característicos de cepas de Alternaria aisladas de tomate para su clasificación quimiotaxonómica. Métodos. Los perfiles de metabolitos secundarios se determinaron por HPLC-MS. Resultados. Los aislamientos de Alternaria obtenidos a partir de tomates con «enmohecimiento negro» pertenecen, según sus características morfológicas, a los grupos especie Alternaria alternata, Alternaria tenuissima y Alternaria arborescens, siendo A. tenuissima el más frecuentemente aislado. Se determinaron los perfiles más característicos de metabolitos secundarios de los grupos especie A. alternata (AOH, AME, TEN), A. tenuissima (AOH, AME, TEN, ácido tenuazónico) y A. arborescens (AOH, AME, TEN, ácido tenuazónico), siendo algunas cepas de este último grupo especie capaces de sintetizar toxinas AAL. Conclusiones. Los perfiles de producción de metabolitos secundarios son una herramienta útil para la diferenciación de aislamientos de Alternaria pertenecientes a grupos especie de esporas pequeñas difícilmente identificables por sus características morfológicas (AU)


Background. Many Alternaria species have been studied for their ability to produce bioactive secondary metabolites, such as tentoxin (TEN), some of which have toxic properties. The main food contaminant toxins are tenuazonic acid, alternariol (AOH), alternariol monomethyl ether (AME), altenuene, and altertoxins i, ii and iii. Aims. To determine the profiles of secondary metabolites characteristic of Alternaria strains isolated from tomato for their chemotaxonomic classification. Methods. The profiles of secondary metabolites were determined by HPLC MS. Results. The Alternaria isolates obtained from spoiled tomatoes belong, according to their morphological characteristics, to the species groups Alternaria alternata, Alternaria tenuissima and Alternaria arborescens, with A. tenuissima being the most frequent. The most frequent profiles of secondary metabolites belonging to the species groups A. alternata (AOH, AME, TEN), A. tenuissima (AOH, AME, TEN, tenuazonic acid) and A. arborescens (AOH, AME, TEN, tenuazonic acid) were determined, with some isolates of the latter being able to synthesize AAL toxins. Conclusions. Secondary metabolite profiles are a useful tool for the differentiation of small spored Alternaria isolates not easily identifiable by their morphological characteristics (AU)


Assuntos
Alternaria/isolamento & purificação , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Micotoxinas , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida de Alta Pressão , Micotoxinas/metabolismo , Ácido Tenuazônico/metabolismo , Toxinas Bacterianas/metabolismo
14.
J Chromatogr A ; 1289: 27-36, 2013 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-23578482

RESUMO

Analogues of the Alternaria mycotoxin tenuazonic acid (TA, biosynthesized by the fungus from the amino acid isoleucine) derived from valine (ValTA), leucine (LeuTA), alanine (AlaTA) and phenylalanine (PheTA) were synthesized and characterized by mass spectrometry (MS) and (1)H nuclear magnetic resonance (NMR) spectroscopy. Concentrations of stock solutions were determined by quantitative (1)H NMR (qHNMR). Two analytical methods based on high performance liquid chromatography (HPLC) and MS detection were developed, one with derivatization with 2,4-dinitrophenylhydrazine (DNPH) and one without derivatization. Limits of detection (LODs) were between 1-3 µg/kg (with derivatization) and 50-80 µg/kg (without derivatization). Respective limits of quantitation (LOQs) were about three times higher. Beside TA, the analogues LeuTA (about 4% of TA content) and ValTA (about 10% of TA content) were found in highly contaminated sorghum infant cereals and sorghum grains. Other analogues were not detected. Quantification of LeuTA and ValTA was performed using [(13)C6,(15)N]-TA as internal standard and matrix matched calibration. Recovery was between 95±11% and 102±10% for both compounds. Precision (relative standard deviation of triplicate sorghum cereal analyses three times during 3 weeks) was 7% for TA (912±60 µg/kg), 17% for LeuTA (43±8 µg/kg) and 19% for ValTA (118±22 µg/kg). These results indicate that several TA-like compounds, which are not yet characterized in aspects of their toxic properties, were detected in sorghum based infant food highly contaminated with TA, already.


Assuntos
Alternaria/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Grão Comestível/química , Contaminação de Alimentos/análise , Espectrometria de Massas/métodos , Micotoxinas/análogos & derivados , Ácido Tenuazônico/análogos & derivados , Alimentos Infantis/análise , Limite de Detecção , Espectroscopia de Ressonância Magnética , Micotoxinas/metabolismo , Sorghum/química , Ácido Tenuazônico/metabolismo
15.
Anal Bioanal Chem ; 405(12): 4149-58, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23397093

RESUMO

The content of tenuazonic acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02-100. The limits of detection and determination were 0.2 and 0.6 µg/L, respectively. The mean recovery of the stable isotope dilution assay was 102 ± 3 % in the range between 1.0 and 100 µg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3-17.3 µg/L or 2.3-10.3 ng/mg(-1) creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 µg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54-81 % after 6 h, depending on matrix and volunteer. After 24 h, 87-93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.


Assuntos
Técnicas de Diluição do Indicador , Micotoxinas/urina , Espectrometria de Massas em Tandem/métodos , Ácido Tenuazônico/urina , Adulto , Cromatografia Líquida/métodos , Creatina/urina , Ingestão de Alimentos , Feminino , Microbiologia de Alimentos/métodos , Glucuronidase/metabolismo , Humanos , Limite de Detecção , Masculino , Pessoa de Meia-Idade , Micotoxinas/metabolismo , Extração em Fase Sólida/métodos , Ácido Tenuazônico/metabolismo , Adulto Jovem
16.
Appl Environ Microbiol ; 79(6): 2103-6, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23335780

RESUMO

This study determined the membrane fluidity of clostridial endospores during treatment with heat and pressure with nisin or reutericyclin. Heating (90°C) reduced laurdan (6-dodecanoyl-2-dimethylaminonaphthalene) general polarization, corresponding to membrane fluidization. Pressure (200 MPa) stabilized membrane order. Reutericyclin and nisin exhibit divergent effects on heat- and pressure-induced spore inactivation and membrane fluidity.


Assuntos
Clostridium/fisiologia , Fluidez de Membrana/efeitos dos fármacos , Fluidez de Membrana/efeitos da radiação , Esporos Bacterianos/fisiologia , 2-Naftilamina/análogos & derivados , 2-Naftilamina/metabolismo , Clostridium/efeitos dos fármacos , Clostridium/efeitos da radiação , Temperatura Alta , Pressão Hidrostática , Lauratos/metabolismo , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Nisina/metabolismo , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/efeitos da radiação , Ácido Tenuazônico/análogos & derivados , Ácido Tenuazônico/metabolismo
17.
Biochim Biophys Acta ; 1767(4): 306-18, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17379181

RESUMO

Tenuazonic acid (TeA) is a natural phytotoxin produced by Alternaria alternata, the causal agent of brown leaf spot disease of Eupatorium adenophorum. Results from chlorophyll fluorescence revealed TeA can block electron flow from Q(A) to Q(B) at photosystem II acceptor side. Based on studies with D1-mutants of Chlamydomonas reinhardtii, the No. 256 amino acid plays a key role in TeA binding to the Q(B)-niche. The results of competitive replacement with [(14)C]atrazine combined with JIP-test and D1-mutant showed that TeA should be considered as a new type of photosystem II inhibitor because it has a different binding behavior within Q(B)-niche from other known photosystem II inhibitors. Bioassay of TeA and its analogues indicated 3-acyl-5-alkyltetramic and even tetramic acid compounds may represent a new structural framework for photosynthetic inhibitors.


Assuntos
Chlamydomonas reinhardtii/enzimologia , Complexo de Proteína do Fotossistema II/antagonistas & inibidores , Ácido Tenuazônico/toxicidade , Sequência de Aminoácidos , Animais , Atrazina/química , Benzoquinonas/metabolismo , Sítios de Ligação , Ligação Competitiva , Chlamydomonas reinhardtii/efeitos dos fármacos , Transporte de Elétrons/efeitos dos fármacos , Dados de Sequência Molecular , Mutação , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/genética , Conformação Proteica , Pirrolidinonas/química , Pirrolidinonas/farmacologia , Ácido Tenuazônico/metabolismo , Tilacoides/efeitos dos fármacos
18.
J Basic Microbiol ; 41(3-4): 179-83, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11512450

RESUMO

Surface cultures of Fusarium culmorum JP15 were found to respond to extracts of other fungi by enhanced production of orange-red fusarubin pigments and formation of aerial mycelium. Two inducers from strain Ulocladium sp. HKI 0226, the new (-)-terpestacin (1) and L-tenuazonic acid (2), were isolated. 1 inhibited syncytium formation by cells infected with respiratory syncytial virus (RSV).


Assuntos
Compostos Bicíclicos com Pontes/metabolismo , Fusarium/crescimento & desenvolvimento , Pigmentos Biológicos/biossíntese , Ácido Tenuazônico/metabolismo , Meios de Cultura , Espectrometria de Massas/métodos , Morfogênese , Vírus Sinciciais Respiratórios/fisiologia
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