Mensuração de biomarcador de exposição às aflatoxinas em fluidos biológicos

Abstract

Aflatoxins are natural substances that present toxic and carcinogenic effects to humans. These substances may be present in human diet or, in specific cases, in the breathing air. Thus, the human exposition to aflatoxins is object of concern. One of the most effective ways to evaluate human exposition to aflatoxins is to measure the presence of biomarkers in biological fluids. Among the possibilities of aflatoxin presence biomarkers, the aflatoxin M 1 (AFM 1), present in human urine and milk, is considered a valid biomarker. The objective of this work was to evaluate the presence of AFM 1 in urine samples from individuals who live in urban and rural areas in the county of Piracicaba, state of São Paulo, Brazil, and in milk of pregnant women from Piracicaba and neighbor cities. Urine-donor individuals were researched in relation to the ingestion of food with high risk of containing aflatoxins through the application of a food frequency questionnaire and 24-hour recall. The analysis of AFM 1 in urine and milk was performed through high-performance liquid chromatography (HPLC) with fluorescence detection. The extract purification and extraction were performed with the aid of immunoaffinity columns. Overall, 69 urine and 18 human breast milk samples were analyzed. Among urine samples, the presence of AFM 1 was detected in 54 (78%), with concentrations ranging from 1.8 to 39.9 pg/mL. No statistical difference was observed between average concentrations detected in the urine of individuals from urban and rural areas, as well as the consumption of aflatoxin risky food. Although the AFM 1 concentrations detected are lower than those reported for other countries, the frequency of positive samples was quite high, showing that the populations studied are exposed to aflatoxins. Thus, further evaluations on the exposition levels should be performed, and considering that the sampling used in this work was punctual, there may be seasonal contamination variations in diet and the contamination level is heterogeneous within a food. No correlation between the consumption of risky food and concentrations detected in urine samples was observed. Only one milk sample presented detected contamination; however, the contamination level was between the limit of detection (LOD) and the limit of quantification (LOQ).

Incidência de aflatoxinas no amendoim (Arachis hypogaea L) cru em casca da região da Alta Paulista-SP, durante o período de 2011 a 2012

“…O estudo das micotoxinas iniciou-se na Inglaterra, em 1960, quando mais de 100.000 perus morreram em curto espaço de tempo, após consumirem ração que possuía em sua constituição torta de amendoim contaminada com aflatoxinas 2 . Entretanto, de acordo com Romero e Gloria 3 , a maioria dos fungos capaz de produzir micotoxinas está frequentemente envolvida na contaminação de produtos agrícolas. Os alimentos são susceptíveis à invasão de fungos micotoxigênicos durante os estágios de produção, processamento, transporte e armazenamento, sendo que as micotoxinas são estáveis, permanecem no substrato mesmo após a destruição do fungo 4 , além de serem resistentes aos processos de torrefação e pasteurização.…”

“…Entre os 18 tipos conhecidos de aflatoxinas, quatro são de interesse médico sanitário e são identificados como aflatoxinas B1, B2, G1 e G2, devido à coloração da fluorescência ("Blue" ou "Green") emitida quando expostas à luz ultravioleta de ondas longas 3 . Apesar de apresentarem quimicamente fórmula molecular bastante semelhante, as aflatoxinas do grupo B possuem anel ciclopentenona B1(C 17 Devido à biotransformação das aflatoxinas B1 e B2, no organismo de mamíferos que tenham ingerido alimentos contaminados, em M1 e M2, estudos tem demonstrado a presença desta toxina na carne, no leite de bovinos e humanos e em outros produtos lácteos 10 .…”