Bioprospecção de fungos endofíticos associados às folhas da axonopus leptostachyus (Poaceae)

Abstract

Endophytic fungi colonize healthy plant organs, and are acknowledged as new sources of natural products. Its special metabolites have potential use in the farming, food and drug industries, with biological activities, such as antimicrobial, cytotoxic, among others. In this work, were selected for the chemical investigation and evaluation of potential bioactivity of its metabolites, the endophytic fungus P90 Magnaporthales sp., isolated from the leaves of the Pantanal grass Axonopus leptostachyus. The endophyte was cultivated in 50 petri dishes with PDA and incubated for 15 days at room temperature. The culture medium and mycelium were randomly cut, transferred to an erlenlenmeyer flask and extracted with EtOAc in shaking incubator for 24h. The material was filtered in low pressure and dried, resulting in a crude extract. The extract was fractionated in preparative scale by adsorption chromatography in normal phase (silica gel) with mobile phase methanol:chloroform:hexane (1:4:5). The resulting fractions were evaluated for detection of antibacterial activity with Minimal Inhibitory Concentration, Minimal Bactericidal Concentration, and biofilm reduction assays, and cytotoxic activity facing human carcinoma strains. The HPLC fractionation resulted in the isolation of 4 substances with superior purity grade, two of them demonstrating activity facing human colorectal cancer strain, one of which also showed antibacterial activity against the bacterial strain Enterococcus faecium. The substances were subsequently submitted to Nuclear Magnetic Resonance spectroscopy analysis for structural elucidation.