Estudo dos metabólitos de Aspergillus fumigatus visando o isolamento de uma substância bioativa contra

Abstract

Tuberculosis (TB) caused by Mycobacterium tuberculosisis one of the most lethal diseases in the world, causing millions of deaths every year. Due to the inadequate treatment and the emergence of multidrug-resistant strains, the search for new antimicrobial compounds have been often reported in the scientific literature. Drugs developed from natural products have been a frequent research target and promising results have been obtained with the discovery of antimicrobial compounds synthesized by endophytic microorganisms. Previous work demonstrated that an endophytic Aspergillus fumigatusspecies,isolated from Copaifera multijugaHayne (copaíba), produces antimicrobial compounds, which are released into the growth substrate. The direct use of this substrate (fermentation broth) in antibiosis assaysagainst M. tuberculosisin vitro allowed detectingantimicrobial activity against the pathogen when compared to the negative control. So, the objective of this work was the analysis and purification of these compounds by the fractionation of A. fumigatusmutant and non-mutantfermentation broth, aiming the selection of fractions with higher capacityfor inhibitM. tuberculosis. Mutants were obtained by the induction of the fungal culture to ultraviolet lightexposition. The wild and mutant derivatives isolateswere tested for antibiosis against the indicator organism, Staphylococcusaureusandthe antimicrobial activity has been evaluated by comparing in vitro antibiosis assaysand fungal extractson n-butanol by High Performance Liquid Chromatography (HPLC). After, n-butanolextracts of wild isolates were subjected to fractionation by Medium PressureLiquid Chromatography (MPLC), and the fractions were evaluated against M. smegmatis. After this test, the fractions that showed antagonistic activity were selected for testing against M. tuberculosis, and analyzed in analyticalHPLC. Among 18 mutants selected, eight showed antagonismagainst S. aureus. A peak with less than a minute of retention was correlated with the antimicrobial activity. On the fractionation, 30 fractions were obtained and among these, only two (F4 and F13) showed activity against M. smegmatisandonly F4 showed antagonism against M. tuberculosiswith an MIC of 256µg/mL. The chromatograms of both F4 andF13 showedpeaks atthe beginning of the analysis. The F4chromatogram showedtwo peaks with retention times of 2.1 and 2.4 minutes. These data will be useful in future optimization and purification of compounds