RESUMO
ABSTRACT: The interest in the use of green tea (Camellia sinensis) (L.) Kuntze (Theaceae) products have increased in the last few years due to its medicinal properties. In the present study, we proposed that headspace solid phase microextraction, in combination with gas chromatography coupled to mass spectrometric could be an efficient method to assess the volatile compounds and to ensure the quality control of C. sinensis. We have also compared the anatomical leaf of different commercial green tea samples, analyzed the information in their labels and determined the presence of foreign materials, moisture content, total ashes and microorganisms. Among the 30 analyzed samples, six were identified as C. sinensis according to the anatomical study; 83.4% were not in accordance with the specified limits for foreign matter and 6.6% for moisture content. All samples presented total ashes in accordance with the current legislation. The analysis indicated the presence of several different volatile organic compounds, being terpenes, hydrocarbons and alcohols the major ones. Microbiological analysis showed that 13.3% and 16.6% of the samples exceeded the limits for counts of molds and yeasts, and for mesophilic bacteria, respectively. 73.3% presented E. coli above the established sanitary limits.
RESUMO: O interesse no chá verde comercial (Camellia sinensis) (L.) Kuntze (Theaceae) tem aumentado nos últimos anos devido suas propriedades medicinais. No presente estudo utilizamos a microextração em fase sólida, em combinação com a cromatografia gasosa acoplada com espectrometria de massas, como um eficiente método de caracterização de compostos voláteis e efetuamos o controle de qualidade de C. sinensis. Comparamos também a anatomia das folhas de diferentes amostras comerciais de chá verde, as informações de seus rótulos e determinamos a presença de matérias estranhas, de microrganismos, o teor de umidade e de cinzas totais. Entre as trinta amostras analisadas, seis foram identificadas como C. sinensis de acordo com o estudo anatômico; 83,4% não estavam de acordo com os limites especificados para matérias estranhas e 6,6% para o teor de umidade. Todas as amostras apresentaram cinzas totais de acordo com a legislação vigente. As análises evidenciaram diversos compostos orgânicos voláteis distintos, sendo majoritários terpenos, hidrocarbonetos e álcoois. As análises microbiológicas mostraram que 13,3 e 16,6% das amostras excedeu os limites de contagem para bolores e leveduras, e para bactérias mesófilas, respectivamente. Por fim, 73,3% das amostras apresentou Escherichia coli acima dos limites sanitários estabelecidos.
RESUMO
Endophytic fungi represent ubiquitous microbial organisms able to live in the tissues of different plants around the world and represent a prolific source of bioactive metabolites. In the present study, the endophytic fungus Aspergillus calidoustus was isolated from the medicinal plant Acanthospermum australe (Asteraceae), and identified using molecular, physiological and morphological methods. A methylene chloride crude extract of A. calidoustus has been produced and subjected to antifungal bioassay-directed fractionation which resulted in the isolation of the two bioactive compounds: ophiobolin K and 6-epi-ophiobolin K. These pure compounds displayed antifungal activity against fungal plant pathogens, protozoal activity against Trypanosoma cruzi, and cytotoxic activity against human tumoral cell lines. The results show that A. calidoustus was able to produce the antifungal and cytotoxic metabolites ophiobolin K and 6-epi-ophiobolin K, which may help the fungus to colonise and occupy the substratum as well as survive in natural environments.