ABSTRACT
O objetivo deste estudo foi avaliar os efeitos do timol e carvacrol contra Aspergillus flavus e a produção de aflatoxinas. Foram determinadas a concentração inibitória mínima (CIM), o espectro fungitóxico e a atividade inibidora de micotoxinas pelo timol e carvacrol. Os resultados mostraram que timol e carvacrol exibiram ação fungicida de acordo com a CIM de 2500 e 30 µg mL-1, respectivamente. Tanto o timol quanto o carvacrol inibiram significativamente o crescimento de A. flavus (p<0,05) a partir de 600 e 15 µg mL-1, respectivamente. A biomassa fúngica, estimada pela determinação da concentração de ergosterol, foi significativamente reduzida (p <0,05) em 2500 µg mL-1 de timol e 250 µg mL-1 de carvacrol. O timol e o carvacrol exibiram efeitos antiaflatoxigênicos em 600 e 125 µg mL-1, respectivamente. O timol e o carvacrol exibiram atividade antifúngica, mas não exibiram alta atividade antiaflatoxigênica. Carvacrol e timol podem ser considerados como potentes compostos naturais antifúngicos contra A. flavus.
The aim of this study was to evaluate the effects of thymol and carvacrol upon production of aflatoxins by Aspergillus flavus and upon its growth. Minimal inhibitory concentration (MIC), fungitoxic spectrum and mycotoxin inhibition were assessed. Results showed thymol and carvacrol exhibited fungicidal action, as determined by MIC values of 2500 and 30 µg mL-1, respectively. Both thymol and carvacrol significantly inhibited growth of A. flavus (p<0.05) at concentrations of 600 and 15 µg mL-1, respectively. Fungal biomass, as estimated by determination of ergosterol concentration, was significantly reduced (p<0.05) at thymol concentrations of 2500 µg mL-1 and at carvacrol concentrations of 250 µg mL-1. Thymol and carvacrol exhibited antiaflatoxigenic effects at concentrations of 600 and 125 µg mL-1, respectively. While both thymol and carvacrol showed possessing antifungal activities, neither were highly antiaflatoxigenic. Carvacrol and thymol might be considered for use as potential antifungal natural compounds against A. flavus.
ABSTRACT
ABSTRACT: Peanuts are a nutritious food consumed worldwide. Some species of the genus Aspergillus, producers of aflatoxins, colonize peanuts. Human exposure to aflatoxins occurs by ingesting contaminated foods. The objective of this paper was to assess the occurrence and dietary exposure of the population to aflatoxins in peanuts commercially available in Maringa, Brazil, from May 2013 to April 2017. A total of 104 peanut samples were evaluated by thin-layer chromatography and confirmed by derivatization with trifluoroacetic acid. The contamination rate detected was 24.0% in average concentration of 13.4µg/kg. Twenty positive samples (19.2%) exceeded the maximum level permitted in Brazil for the sum of four aflatoxins. Estimated probable daily intake was 1,28 µg/kg body weight/day, exceeding the Provisional Maximum Tolerable Daily Intake (0.001μg/kg body weight/day). According to the high levels of aflatoxins found in peanuts, there is need for further monitoring the presence of aflatoxins in peanuts in natura to reduce the levels of contamination.
RESUMO: O amendoim é um alimento nutritivo e muito consumido no mundo todo. Algumas espécies de fungos do gênero Aspergillus, produtores de aflatoxinas, colonizam o amendoim. A exposição humana as aflatoxinas ocorre por meio do consumo de alimentos contaminados. O objetivo deste estudo foi avaliar a ocorrência e exposição da população as aflatoxinas em amendoim comercializado no município de Maringá, Brasil, durante o período de maio de 2013 a abril de 2017. Foram avaliadas 104 amostras de amendoim por análise cromatográfica e confirmadas por derivação com ácido trifluoroacético. A frequência de contaminação foi de 24,0% em concentração média de 13,4µg/kg. Vinte amostras positivas (19,2%) apresentaram-se acima do limite máximo permitido no Brasil para a somatória das quatro aflatoxinas. A ingestão diária provável média encontrada foi de 1,28µg/kg peso corpóreo/dia, superando a ingestão diária máxima tolerável provisória (0,001µg/kg peso corpóreo/dia). De acordo com os elevados teores de aflatoxinas encontrados em amendoim, há necessidade de um maior monitoramento da presença de aflatoxinas em alimentos, tendo em vista a redução nos níveis de contaminação do amendoim in natura.
ABSTRACT
Abstract Aflatoxins are mutagenic, carcinogenic, and teratogenic mycotoxins. The objective of this work was to study the presence of aflatoxigenic Aspergillus in commercial Bulgur wheat in the city of Maringá, Paraná, Brazil. Thirty samples of commercial Bulgur wheat, acquired in the period of August 2011 to January 2012, were evaluated. The enumeration analysis showed that samples had up to 273.3 CFU of molds and 133.3 CFU of aflatoxigenic Aspergillus per gram of wheat. Forty-two monosporic isolates were obtained and identified as Aspergillus flavus. The isolates were analyzed regarding their aflatoxigenic potential by culture in coconut milk agar; hydroxide vapor exposure; chromatography; and polymerase chain reaction (PCR) targeting genes that code enzymes of the aflatoxins synthesis pathway. Some of the isolates were confirmed to be aflatoxin producers and several of them presented a genetic profile of aflatoxin synthesis. The obtained results demonstrated that Bulgur wheat A. flavus contamination is concerning.