Caracterização química e atividade biológica de metabólitos especiais obtidos de fungos endofíticos associados às folhas de Vochysia divergens POHL (Vochysiaceae)

Abstract

The endophytic microrganisms colonize the houseplants and generally inhabit their roots and aerial parts such as leaves and stems, but apparently not cause any harm to their hosts, living in symbiotic association. In addition to their number of important functions to the host, these microrganisms are potentially useful in agriculture and industry, particularly in the pharmaceutical and crop protection. Against this background, this research seeks bioactive substances from the chemical study of endophytic fungi associated with plant species Vochysia divergens (Cambará). From this perspective, the endophytic fungi were isolated and purified from the leaves, using appropriate techniques, subsequently grown on solid medium (Potato Dextrose Agar) and subjected to extraction of metabolites of interest with organic solvent to yield crude extracts. These extracts were tested against biological assays, focusing on the detection of potential antifungal and antibacterial activities, and also analyzed by TLC, HPLC and 1 H NMR to assess the chemical profile of metabolites present. The analyze of this information was based on spectra definition, chromatograms resolved, the crude extract masses on a small scale and biological activity indicated the fungi with the best potential for larger scale growth. The strains of interest were grown on a larger scale and its crude extracts subjected to chromatographic fractionation, aiming to isolate and characterize the bioactive substances. From the crude extract of Nigrospora oryzae, four fungal metabolites were identified through special spectroscopic 1D and 2D and gave 5-methyl-melleine, 5-methyl-5-methyl-8-methoxy melleine, sclerine and Daldinone A. Lasiodiplodin was isolated from the Pseudofusicoccum stromaticum fungus. The Nigrospora sphaerica fungus produced two novel metabolites 10,11-dihydroxy-5,5,8-trimethyl-4-oxocicloundeca-1,8-dienecarbaldeide and the 12,13,14,15-tetrametil-6,7,8,9,10,11-hexaidro-1H-azepino[5,4,3-cd]indólico. Thus, this study aims to search for new potential bioactive agents, in addition to program rational studies of endophytes chemistry and contribute to the knowledge of diversity and biotechnological potential of microorganisms associated with V. divergens.