RESUMO
A study on the potential of houseflies (Musca domestica L.) to spread fungal spores in Gauteng Province, South Africa proved that houseflies are vectors for fungal spores. Therefore, there is a need to determine the toxigenic potentials and to identify the mycotoxins produced by fungal isolates derived from this study. In total 377 potentially toxigenic isolates of Aspergillus (186), Fusarium (85) and Penicillium (106) species (spp.) were isolated. These isolates were further tested for their ability to produce aflatoxins (AFs) [aflatoxin B1, B2, G1 and G2], deoxynivalenol (DON), fumonisin B1 (FB1) ochratoxin A (OTA), and zearalenone (ZEA) by high-performance liquid chromatography (HPLC) respectively. Strains of A. flavus and A. parasiticus belonging to the genera of Aspergillus were found to be the main producers of AFB1, AFB2, AFG1, and AFG2, while A. carbonarius, A. niger and A. ochraceus produced OTA. Fumonisin B1 was produced by F. verticillioides and F. proliferatum with concentrations ranging from 20 to 1834µg/kg and 79 to 262µg/kg respectively. Deoxynivalenol produced mainly by F. culmorum (2-6µg/kg), F. graminearum (1-4µg/kg), F. poae (1-3µg/kg), and F. sporotrichioides (2-3µg/kg) species was the least detected toxin in this study. The high mycotoxins levels produced in isolates from houseflies in this study are regarded as unsafe, especially when international legislated tolerance levels for mycotoxins are considered. Thus, possible human exposure to mycotoxins may pose concerns with respect to human health and demands constant and consistent investigation.
Assuntos
Aspergillus/isolamento & purificação , Fusarium/isolamento & purificação , Moscas Domésticas/microbiologia , Micotoxinas/análise , Micotoxinas/biossíntese , Penicillium/isolamento & purificação , Animais , Aspergillus/classificação , Aspergillus/metabolismo , Cromatografia Líquida de Alta Pressão , Contagem de Colônia Microbiana , Fusarium/classificação , Fusarium/metabolismo , Penicillium/classificação , Penicillium/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , África do Sul , Esporos Fúngicos/isolamento & purificação , Esporos Fúngicos/metabolismoRESUMO
Several insects that act as vectors, including houseflies (Musca domestica L.), are often considered to be an important source of fungal contamination in human foods. Houseflies are also involved in the transmission of bacterial pathogens that may pose a serious hazard to human health. Thus, the rural population of South Africa, as typified by that in the Gauteng Province investigated in this study, is at high risk from fungal exposure disseminated by houseflies and it is therefore important to assess the role of flies in contaminating various food commodities. Eighty four samples of houseflies (captured from households and pit toilets) were studied for their potential to carry fungal spores into food commodities. The fungi occurring in samples of raw maize (15) and porridge (19) were also assessed. Fungal isolates were identified based on morphological characteristics by conventional identification methods. Fifteen genera of fungi were isolated and identified, of which Aspergillus, Fusarium, Penicillium, Cladosporium, Moniliella and Mucor were the most prevalent in all three sample types analysed. The incidence rates of fungal contamination per total fungal count isolated in houseflies, maize and porridge were recorded with mean fungal load of 2×10(8) CFU/ml, 1×10(7)CFU/g and 2×10(7)CFU/g respectively. Additionally, A. flavus, A. parasiticus, F. verticillioides, F. proliferatum, P. verrucosum, P. aurantiogriseum and M. suaveolens were the most frequent fungal isolates in houseflies with incidence rate of 34%, 11%, 27%, 21%, 22%, 17% and 32% respectively. F. verticillioides, A. flavus, A. niger and P. oslonii were the most prevalent species contaminating porridge and maize with incidence rate of 23%, 32%, 16% and 28% in maize samples, while incidence rates of 59%, 15% and 29% were recorded in porridge samples with the exception of F. verticillioides. The prevalence of these genera of fungi may pose serious health risks.
Assuntos
Ascomicetos/isolamento & purificação , Aspergillus/isolamento & purificação , Microbiologia de Alimentos , Fusarium/isolamento & purificação , Moscas Domésticas/microbiologia , Penicillium/isolamento & purificação , Animais , Contagem de Colônia Microbiana , Grão Comestível/microbiologia , Humanos , África do Sul , Zea mays/microbiologiaRESUMO
Houseflies are the commonest insects which have increasingly overcrowded human dwellings, particularly in rural areas and constitute a health hazard. In the environment they move back and forth by feeding and breeding on food commodities and filth. This may lead to the spread of diseases and also mycotoxin-producing fungi. Thus frequent exposure to the activity of such houseflies will have an impact on the welfare of humans. The study investigated the natural occurrence of fungal contamination in housefly samples captured from different households and pit toilets from a rural community in South Africa. Fungal contamination data were based on the prevalence, contamination level and morphological characteristics of the different identified species. A total of 497 fungal isolates of 15 genera including Aspergillus (37%), Fusarium (17%), Penicillium (21%), Alternaria (1.4%), Chrysosporium (2%), Cladosporium (0.2%), Curvularia (0.4%), Epicoccum (1%), Eupenicillium (1%), Moniliella (9%), Mucor (2%), Nigrospora (1%), Rhizopus (2%), Scopulariopsis (2%) and Yeasts (3%) were identified from the external surfaces of both female and male houseflies. The range of fungal contamination per total fungal count isolated from female and male houseflies were recorded with mean fungal load of 4.1×10(6), 8.4×10(6), 4.4×10(6), 3.3×10(5), 9.8×10(6), 2.2×10(4), 5.6×10(4), 2.9×10(6), 5.2×10(6), 4.7×10(6), 4.5×10(7), 4.6×10(6), 2.3×10(6), 4.9×10(7) and 6.4×10(6)CFU/ml, respectively. However, the range from The most dominant fungal isolates of the female housefly samples were Aspergillus flavus, Fusarium verticillioides, Penicillium verrucosum and Moniliella suaveolens, while A. flavus, Aspergillus parasiticus, F. verticillioides, Fusarium proliferatum and Penicillium aurantiogriseum were most prevalent in male samples. The study proves that housefly is a vector for fungal spores. Therefore, it is crucial to implement housefly-control measures to curb the spread of diseases.
Assuntos
Fungos/classificação , Moscas Domésticas/microbiologia , Insetos Vetores/microbiologia , Animais , Aspergillus/classificação , Aspergillus/isolamento & purificação , Características da Família , Feminino , Fungos/isolamento & purificação , Fusarium/classificação , Fusarium/isolamento & purificação , Humanos , Masculino , Penicillium/classificação , Penicillium/isolamento & purificação , Fatores de Risco , África do SulRESUMO
Fusarium toxins with reference to fumonisin B1 (FB1) have long been regarded as contaminants of maize and maize-based related products. However, when consumed they can cause intoxication, especially in humans. Therefore, effective quantitative methods for assessing the dietary exposure of this toxic fungal metabolite are required. The objective of this investigation was to evaluate the effect on the use of a bio-wipe kit, which is a faecal material collection kit, to detect the presence of FB1. Faecal materials were collected from a rural farming community in Gauteng Province, South Africa. In total, 200 samples of faecal material were analysed for Fusarium species using a serial dilution method, while FB1 was further analysed and quantified by reversed-phase TLC and HPLC. The study showed the presence of 11 different Fusarium species grown on potato dextrose agar culture medium of which F. verticillioides and F. proliferatum, producers of FB1, and F. oxysporum were the dominant species. Fumonisin B1 was recorded at an incidence rate of 65% of the total using TLC. Results from HPLC showed that 84% were positive at different ranges of concentration for FB1. This study supports the use of a bio-wipe as a rapid method to determine human exposure to FB1.
Assuntos
Carcinógenos Ambientais/análise , Fezes/química , Doenças Transmitidas por Alimentos/diagnóstico , Fumonisinas/análise , Fusariose/diagnóstico , Fusarium/isolamento & purificação , Kit de Reagentes para Diagnóstico , Biomarcadores/análise , Biomarcadores/metabolismo , Carcinógenos Ambientais/metabolismo , Carcinógenos Ambientais/toxicidade , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Cromatografia em Camada Fina , Fezes/microbiologia , Contaminação de Alimentos , Microbiologia de Alimentos , Doenças Transmitidas por Alimentos/epidemiologia , Doenças Transmitidas por Alimentos/metabolismo , Doenças Transmitidas por Alimentos/microbiologia , Fumonisinas/metabolismo , Fumonisinas/toxicidade , Fusariose/epidemiologia , Fusariose/metabolismo , Fusariose/microbiologia , Fusarium/crescimento & desenvolvimento , Fusarium/metabolismo , Humanos , Incidência , Viabilidade Microbiana , Prevalência , Saúde da População Rural , África do Sul/epidemiologia , Especificidade da EspécieRESUMO
Aflatoxins (AFs) are naturally occurring secondary metabolites. This toxin is principally produced by Aspergillus flavus and Aspergillus parasiticus in compound feeds worldwide. Compound feeds are feeds blended from various raw materials and additives. Contaminations of these feeds by AFs and its possible transmission into edible materials like milk, egg and organs of the body, are a serious problem. Expression of the Nor~1 (aflD) gene is the main factor responsible for AFs production. For this reason, a study was carried out to establish a correlation between levels of AFs and determinant gene (Nor~1) in South African compound feeds. To achieve this, compound feeds (n=30) were analyzed for Nor~1 gene using real time polymerase chain reaction (RT-PCR), while AFs levels in similar samples were estimated using high-performance liquid chromatography (HPLC) after an immune-affinity clean-up extraction procedure. Results indicated that AFs levels in positive samples ranged from 0.7 to 33.0 ppb. These levels generally did not correlate (R(2)=0.093) with those of Nor~1 gene in similar samples. Consequently, Nor~1 gene levels established via RT-PCR cannot be used as a predicting model for AFs in compound feeds. Only four of the feeds analyzed, specifically poultry feeds, contained levels of AFs above the regulatory limits of 10 ppb established in South Africa (S.A.). This should be considered unsafe when consumed on a continuous basis and may pose some health related problems especially when AFs are found together with other significant mycotoxins such as ochratoxins (OTs) and/or fumonisins (FBs).
Assuntos
Aflatoxinas/análise , Oxirredutases do Álcool/genética , Ração Animal/análise , Aspergillus/genética , Microbiologia de Alimentos , Proteínas Fúngicas/genética , Animais , Álcool Oxidorredutases Dependentes de NAD(+) e NADP(+) , Reação em Cadeia da Polimerase em Tempo Real , África do Sul , Estatística como AssuntoRESUMO
Fusarium species (spp.) and fumonisin B1 (FB1) contaminations were monitored in maize and porridge consumed by a rural population of Limpopo Province, South Africa. Faecal samples were also analysed for FB1 as a means of estimating the degree of dietary exposure to this mycotoxin. In total, 142 samples of maize (n = 54), porridge (47) and faeces (41) were screened for Fusarium spp. using a serial dilution technique followed by DNA sequencing, while FB1 was further screened and quantified by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), respectively. At least four species of Fusarium were identified, of which F. verticillioides was the most prevalent in all three sample types analysed. The contamination levels of FB1 were significantly higher in 87% of maize sampled (range = 101-53,863 µg kg⻹) as compared with porridge (74% incidence rate; range = 0.2-20 µg kg⻹) and faecal samples (100% incidence rate; range = 0.3-464 µg kg⻹). Thus, it can be deduced that the level of human exposure to FB1 via the consumption of maize was high as several samples contained levels exceeding 1000 µg kg⻹, which was strongly supported by the levels found in faecal samples. Further data revealed that a high proportion of FB1 is destroyed or removed by processing maize into porridge. As maize porridge is consumed as a staple, the low levels found provide a means to limit exposure to FB1. Levels of FB1 found in the faeces which were higher indicate that other foods contaminated with the toxin are also consumed.
Assuntos
Produtos Agrícolas/microbiologia , Contaminação de Alimentos , Fumonisinas/análise , Fusarium/isolamento & purificação , Doenças das Plantas/microbiologia , Sementes/microbiologia , Zea mays/microbiologia , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Cromatografia em Camada Fina , Produtos Agrícolas/química , Produtos Agrícolas/crescimento & desenvolvimento , Fezes/química , Manipulação de Alimentos , Microbiologia de Alimentos , Fumonisinas/administração & dosagem , Fumonisinas/metabolismo , Fusarium/classificação , Fusarium/crescimento & desenvolvimento , Fusarium/metabolismo , Temperatura Alta , Humanos , Tipagem Molecular , Técnicas de Tipagem Micológica , Saúde da População Rural , Sementes/química , Sementes/crescimento & desenvolvimento , África do Sul , Especificidade da Espécie , Zea mays/química , Zea mays/crescimento & desenvolvimentoRESUMO
Spontaneous nephropathy in Bulgaria, which is observed frequently during meat inspection and which differs morphologically from the classical description of mycotoxic porcine/chicken nephropathy as made in Denmark, was found to have a multi-mycotoxic aetiology being mainly provoked by a combined effect of ochratoxin A, penicillic acid and fumonisin B1 in addition to a not-yet-known metabolite. Mean contamination levels of ochratoxin A were consecutively low (188.8 and 376.4 microg kg(-1)) in contrast to high contamination levels of fumonisin B1 (5564.1 and 3254.5 microg kg(-1)) and penicillic acid (838.6 and 904.9 microg kg(-1)) for 2006 and 2007, respectively. Some other mycotoxins with lower importance such as citrinin, penitrem A, etc., may also influence clinicopathological picture of this nephropathy. A heavy contamination with Gibberella fujikuroi var. moniliformis (Fusarium verticillioides) and Penicillium aurantiogriseum complex (mainly Penicillium polonicum) was observed in almost all examined feed samples coming from pig and chick farms with nephropathy problems from Bulgaria. In contrast, low contamination with Aspergillus ochraceus, Penicillium verrucosum and Penicillium citrinum was observed in the same feed samples and these species were isolated as very rare components of the mycobiota.
Assuntos
Nefropatia dos Bálcãs/etiologia , Nefropatias/veterinária , Micotoxicose/veterinária , Doenças das Aves Domésticas/etiologia , Doenças dos Suínos/etiologia , Ração Animal/análise , Ração Animal/toxicidade , Animais , Bulgária , Galinhas , Sinergismo Farmacológico , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Fumonisinas/toxicidade , Humanos , Nefropatias/etiologia , Nefropatias/patologia , Micotoxicose/etiologia , Micotoxicose/patologia , Micotoxinas/análise , Micotoxinas/toxicidade , Ocratoxinas/toxicidade , Ácido Penicílico/toxicidade , Sus scrofa , Suínos , Doenças dos Suínos/patologiaRESUMO
The objective of this study was to test the hypothesis that autoantibodies to phospholipids and to oxidised low-density lipoprotein (ox-LDL) are increased in pre-eclamptic and eclamptic women compared with normal pregnancy. Serum concentrations of autoantibodies to ox-LDL and to cardiolipin were measured in 21 non-pregnant controls, 29 pregnant controls, 21 pre-eclamptic and six eclamptic women. Concentrations of IgG antibodies to ox-LDL and to cardiolipin were not significantly different in women with eclampsia as compared with the non-pregnant controls, pregnant controls and pre-eclampsia. Concentrations of IgM antibodies to cardiolipin were significantly lower in women with pre-eclampsia compared with non-pregnant controls and eclampsia. All three pregnant states differ markedly from the non-pregnant controls, of whom only 5% (1 of 21) had "high positive" IgG antibodies. These results suggest that ACAs rise as a result of the pregnant state rather than as a result of preeclampsia or eclampsia. According to these results, there is no evidence of increased production of serum autoantibodies against modified LDL in African women with pre-eclampsia, which may reflect reduced lipid peroxidation involving lipoproteins or no link at all. In addition, IgG and IgM anticardiolipin antibodies have no diagnostic value in preeclampsia and eclampsia.
Assuntos
Anticorpos Anticardiolipina/imunologia , Anticorpos Antifosfolipídeos/imunologia , Cardiolipinas/imunologia , Eclampsia/imunologia , Lipoproteínas LDL/imunologia , Pré-Eclâmpsia/imunologia , Adolescente , Adulto , Anticorpos Anticardiolipina/sangue , Anticorpos Antifosfolipídeos/sangue , Síndrome Antifosfolipídica/complicações , Biomarcadores , Reações Cruzadas/imunologia , Eclampsia/diagnóstico , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulinas/imunologia , Pré-Eclâmpsia/diagnóstico , Pré-Eclâmpsia/etiologia , GravidezRESUMO
Aflatoxin B1 (AFB1 ) is a carcinogenic mycotoxin found in feeds and in airborne grain dusts. Aflatoxin B1 requires biotransformation to the AFB1-8,9 epoxide (AFBO) by a bioactivation system and subsequent covalent binding to DNA or proteins, to exert its carcinogenic potential. The lung contains cytochrome P450, prostaglandin-H-synthase, lipoxygenase, epoxide hydrolase and other bioactivation enzymes, and is thus a potential target for the effects of AFB1 via the routes of inhalation and ingestion. The A549 human epithelioid lung cell line and the methylthiazol tetrazolium (MTT) bioassay were used to investigate the cytotoxicity of AFB1 and its chemically synthesised epoxide (AFBO) in vitro. Statistical analysis of the MTT results indicated that there were overall significant differences between the control and both the AFB1-treated (p < 0.0001) and AFBO-treated cells (p = 0.002). However, there was no significant difference between AFB1 and AFBO-treated cells, when the entire range of concentrations were assessed against each other (p = 0.2877). When analysed at each concentration, only at 0.01 mM was there a significant difference between the effects of AFB1 and AFBO (p = 0.0358). The results of this investigation show that AFB1 and AFBO are both cytotoxic in the A549 cell line.
Assuntos
Aflatoxina B1/análogos & derivados , Aflatoxina B1/toxicidade , Carcinógenos/toxicidade , Pulmão/efeitos dos fármacos , Aflatoxina B1/síntese química , Células Epitelioides/efeitos dos fármacos , Formazans , Humanos , Sais de Tetrazólio , Células Tumorais CultivadasRESUMO
BACKGROUND: The objective of this study was to test the hypothesis that maternal plasma, cord plasma and placental tissue lipid peroxidation products are increased and antioxidants are decreased in women with pre-eclampsia. METHODS: Placenta, maternal and cord plasma were collected at delivery from 29 normal, 21 pre-eclamptic and six eclamptic women. Plasma was collected from 21 non-pregnant matched controls. The analyses were measured by HPLC and colorimetric assay. RESULTS: Plasma maternal concentrations of uric acid, LPO, MDA, ascorbic acid, vitamin E and cholesterol were not significantly different in pre-eclampsia as compared with normal pregnancy. Plasma concentrations of ascorbic acid and vitamin E were not significantly different in normal pregnancy as compared with the non-pregnant controls. Cord plasma concentrations of MDA were significantly higher in eclampsia (1.16+/-0.26 micromol/l) as compared with normal pregnancy (0.79+/-0.05 micromol/l, p<0.02) and pre-eclampsia (0.83+/-0.05 micromol/l, p<0.05). Cord plasma concentrations of vitamin E were significantly higher in eclampsia (21.3+/-7.5 micromol/l) as compared with normal pregnancy (10.2+/-1.1 micromol/l, p<0.01) and pre-eclampsia (10.4+/-1.8 micromol/l, p<0.04). Placental concentrations of LPO, MDA and ascorbic acid were not significantly different in pre-eclampsia as compared with normal pregnancy. Plasma cord concentrations of LPO and placental concentrations of vitamin E were undetected for normal pregnant, pre-eclamptic and eclamptic women respectively. Uric acid concentrations were significantly increased in eclampsia as compared with the non-pregnant controls (p<0.0001), normal pregnant controls (p<0.0001) and pre-eclampsia (p<0.008). CONCLUSIONS: The findings in this study do not show any evidence of deficiency in the maternal protective antioxidant systems or increased production of lipid peroxidation products, LPO and MDA in African women with pre-eclampsia as compared with normal pregnancy. However, there was evidence of increased cord plasma concentrations of MDA and vitamin E in eclampsia as compared with normal pregnancy and pre-eclampsia. The placenta may be effective in removing MDA. The antioxidant uric acid serves as a protective role whilst the antioxidant and oxidant capacity in the different study groups remained unchanged.
Assuntos
Peróxidos Lipídicos/sangue , Estresse Oxidativo , Pré-Eclâmpsia/metabolismo , Adolescente , Adulto , Ácido Ascórbico/sangue , População Negra , Estudos de Casos e Controles , Colesterol/sangue , Eclampsia/sangue , Eclampsia/metabolismo , Feminino , Sangue Fetal/metabolismo , Humanos , Peróxidos Lipídicos/metabolismo , Malondialdeído/sangue , Placenta/metabolismo , Pré-Eclâmpsia/sangue , Gravidez/sangue , Gravidez/metabolismo , Terceiro Trimestre da Gravidez/sangue , Vitamina E/sangueRESUMO
We surveyed households in rural and urban areas of KwaZulu Natal, South Africa, to assess the exposure of the inhabitants to fumonisin B(1) (FB(1)), a mycotoxin produced by Fusarium verticillioides. In southern African regions maize, used as a staple food by the population, is prone to F. verticillioides infection. Furthermore, high levels of FB(1) in maize have been associated with esophageal cancer in South Africa. We assessed exposure of the population to FB(1) at three levels, namely, by analyzing stored maize, plate-ready food, and feces. The positions of participating households in the rural area were recorded using geographic information systems (GIS) for ease and accuracy of follow-up. Of the 50 rural maize samples examined, 32% had levels of FB(1) ranging from 0.1-22.2 mg/kg, whereas 29% of the 28 cooked maize (phutu) samples contained FB(1) ranging from 0.1-0.4 mg/kg. The incidence and levels of FB(1) in feces were 33% and 0.5-39.0 mg/kg, respectively. Of the 49 urban maize samples analyzed 6.1% had a range of 0.2-0.5 mg/kg FB(1), whereas 3 of 44 fecal samples (6%) ranged between 0.6 and 16.2 mg/kg. No FB(1) was detected in urban phutu samples. Because these levels are lower than those published from regions in South Africa with high incidence of esophageal cancer, it may be concluded that the risk of esophageal cancer from FB(1) exposure is lower in the KwaZulu Natal region.
Assuntos
Ácidos Carboxílicos/efeitos adversos , Exposição Ambiental/estatística & dados numéricos , Neoplasias Esofágicas/epidemiologia , Fumonisinas , Micotoxinas/efeitos adversos , Ácidos Carboxílicos/análise , Cromatografia Líquida de Alta Pressão , Neoplasias Esofágicas/etiologia , Fezes/química , Contaminação de Alimentos/análise , Humanos , Incidência , Micotoxinas/análise , Saúde da População Rural , África do Sul/epidemiologia , Saúde da População Urbana , Zea maysRESUMO
The objective of this study was to test the hypothesis that TNF-alpha, TNFp55 receptor and sICAM-1 are markers of immune activation, protective response to concentrations of TNF-alpha and endothelial cell activation, respectively, in pre-eclampsia. In addition, MPO and sL-selectin were selected as blood discriminators of neutrophil activation. This was a cross-sectional study comparing 21 non-pregnant controls, 29 normal pregnant controls, 21 pre-eclamptic and six eclamptic women. Blood concentrations of TNF-alpha, sTNFp55 receptor, sICAM-1, sL-selectin, myeloperoxidase, leucocyte count, neutrophil count, C-reactive protein and gamma-glutamyl transferase were estimated. The neutrophil count was significantly decreased in pre-eclampsia compared with normal pregnancy (9.12+/-0.95 vs. 12.52+/-0.80 x 10(9)/l, P<0.01). Serum concentrations of sL-selectin were significantly higher in non-pregnant controls compared with pregnant controls (P<0.0001), pre-eclampsia (P<0.0001) and eclampsia (P<0.0001). Serum concentrations of TNF-alpha, sTNFp55 receptor, sICAM-1, sL-selectin and MPO were not significantly different in women with pre-eclampsia compared with normal pregnancy. Serum concentrations of TNF-alpha, sTNFp55, sICAM-1, sL-selectin and MPO did not discriminate between normal and pre-eclamptic pregnancies. The high neutrophil count in normal and eclamptic pregnancies and the lack of shedded L-selectin suggests that neutrophil exudation to inflammatory sites was increased in women with an accompanying inflammatory response.
RESUMO
Fumonisin B1 (FB1) is a compound that occurs frequently in rural foods and feeds, creating health hazards. When ingested, FB1 does not appear to change in structure and is mostly excreted unchanged in faeces within 24 h. Twenty human stool samples obtained from rural school children of Vulamehlo, south of Durban (South Africa), were analysed for FB1, as well as 23 urban control samples obtained from various households within the Durban metropolitan area. The samples were freeze-dried and ground to a fine powder. A fraction of each sample was extracted three times with aqueous ethylenediaminetetraacetic acid at pH 5.2. The pooled extracts were purified using reversed phase C18 solid phase extraction cartridges. Analytical high performance liquid chromatography was used to quantitate the amount of FB1 as an o-phthaldialdehyde (OPA) derivative in the extracts. The rural (35%) and the urban samples (9%) showed the presence of FB ranging from 790 to 19 560 ng g(-1) of freeze dried stool. It was concluded that this method could be used as a routine biomarker for short term human exposure to FB1 in contaminated food.
RESUMO
The toxins produced by Fusarium moniliforme, which include fumonisins, are possible human carcinogens. Fumonisins are inhibitors of de novo sphingolipid biosynthesis. Alterations of the ratio of sphinganine (Sa) to sphingosine (So) in urine and serum has been proposed as a possible biomarker of exposure to this toxin. A new method was developed for their analysis in tissues and urine. This work describes the further adaptation of the method to the analysis of Sa and So in serum and its validation in sera of untreated and fumonisin B1 (FB1 ) treated rats and mice. No significant differences in the Sa/So ratios were observed in the FB1 treated rats. In mice, the increase was only of marginal statistical significance. Determination of Sa/So ratios in human sera could readily be made in small volumes (from 0.3 to 0.5 ml) of serum.
Assuntos
Biomarcadores/sangue , Ácidos Carboxílicos/toxicidade , Fumonisinas , Esfingosina/análogos & derivados , Esfingosina/sangue , Animais , Cromatografia Líquida de Alta Pressão/métodos , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Ratos , Espectrometria de FluorescênciaRESUMO
Seven alkyl and aryl homologues of O-methylsterigmatocystin (OMST) were synthesised and fed in separate experiments to a mutant of Aspergillus parasiticus capable of converting sterigmatocystin (ST) to aflatoxin B1 (AFB1). Their conversion to AFB1 was followed over a time period and it was found that O-propylsterigmatocystin (OPRST) was converted to AFB1 more rapidly than O-ethylsterigmatocystin (OEST) or OMST or ST itself. The aryl derivative O-benzoylsterigmatocystin (OBzST) was converted at the slowest rate. These results show that alkyl and aryl homologues of OMST may be converted to AFB1, suggesting that the methylation of ST is not an absolute requirement for its conversion to AFB1. It seems likely that whatever enzyme(s) are involved in this process exhibit relative specificity. As to whether alkylation of ST is an obligatory step in AFB1 biosynthesis is neither supported nor disproved as the fungal cells used are presumably capable of methylating ST. The fact that the propyl derivative showed fastest conversion is not necessarily significant as this may be due to faster diffusion of the least polar of the derivatives through the cell membrane.
Assuntos
Aflatoxinas/metabolismo , Aspergillus/metabolismo , Esterigmatocistina/metabolismo , Aspergillus/genética , Biotransformação , Mutação , Esterigmatocistina/análogos & derivados , Esterigmatocistina/síntese química , Esterigmatocistina/farmacocinéticaRESUMO
The relationship of oxidants and anti-oxidants in preeclampsia with reference to the dietary anti-oxidants vitamin C and vitamin E was investigated. Three groups of patients were studied in the third trimester of pregnancy: normotensives ( n = 32), mild pre-eclamptics ( n = 15) and severe pre-eclamptics ( n = 31) with a group of healthy non-pregnant women ( n = 18) serving as a control. Total anti-oxidant concentration, the concentrations of vitamin C, vitamin E, superoxide dismutase, uric acid and the concentration of total oxidant activity, as reflected by lipid peroxides, were measured in plasma or red blood cells. Total anti-oxidants and vitamin C concentrations were significantly lower in pre-eclamptic patients than in pregnant controls (P < 0.05), with the concentrations in the pregnant controls being significantly lower than in the non-pregnant controls (P < 0.05). There was no significant difference in vitamin E concentration for all four groups. Superoxide dismutase activity was significantly lower in the normal pregnancy group. Lipid peroxides were significantly increased in the three pregnant groups (P < 0.05) with no differences noted between these groups. The relationship of oxidants to anti-oxidants in pregnancy and pre-eclampsia is dependent on many factors but balance appears to be upset in pre-eclampsia. The reduction in anti-oxidant concentrations in pre-eclampsia suggests either a primary deficit or consumption of the anti-oxidants measured. Of the dietary anti-oxidants studied, vitamin C was most affected in pre-eclampsia.
RESUMO
The fumonisins (FBs) are a group of closely related mycotoxins that are prevalent in maize. They were isolated from strains of Fusarium moniliforme (Sheldon), which were implicated in the aetiology of human oesophageal cancer in the Transkei, South Africa. Their discovery explained the cause of equine encephalomalacia, or "hole in the head" syndrome, when it was found by feeding trials in horses that they elicited the disease. Subsequently, they were found to cause hepatic cancer in rats and pulmonary oedema in pigs, with most animal species tested showing liver and kidney damage. FB1 is the most important of the group and, although poorly absorbed from the gastrointestinal tract, its action is at the cellular level, affecting sphingolipid metabolism. Ceramides derived from sphingosine metabolism are cell regulatory factors affecting, among other things, DNA synthesis. Because FB1 has a close molecular resemblance to sphinganine, it interferes with ceramide biosynthesis and, hence, the processes that it regulates, which is thought to explain its carcinogenic properties. Studies on the FBs are still at a relatively early stage, but it is already clear that they play an important role in animal mycotoxicoses and, by implication, in human disease. A more positive aspect is that they will be used in elucidating the role of sphingolipids in cellular regulation.
Assuntos
Doenças dos Animais/induzido quimicamente , Carcinógenos Ambientais/toxicidade , Fumonisinas , Micotoxinas/toxicidade , Animais , Carcinógenos Ambientais/efeitos adversos , Neoplasias Esofágicas/induzido quimicamente , Neoplasias Esofágicas/veterinária , Fusarium/química , Humanos , Estrutura Molecular , Micotoxinas/química , Micotoxinas/isolamento & purificaçãoRESUMO
During the year of 1994, 417 samples of agricultural commodities, comprising: maize, compound animal feeds, oil seeds, soya bean, fish meal and forage were examined for fungi and over 20 mycotoxins using a multi-screen augmented with individual assays. Trichothecenes had the highest incidence of over 19% in all samples received, followed by aflatoxin at 6% and then zearalenone at 3%. Selected samples (73) were analyzed for fumonisin B1 and of these, 69 (94%) were found to be positive. Because of this result and high incidence of Fusarium spp. (over 70%) in maize and maize containing feeds, which was higher than either Aspergillus spp. (19%) or Penicillium spp. (33%), attention is drawn to the actual and potential presence of fumonisin in the food chain.