Curvularin produced by endophytic Cochliobolus sp. G2-20 isolated from Sapindus saponaria L. and evaluation of biological activity

Abstract

Endophytic fungi are organisms that live within intercellular tissues of healthy plants and are able to produce a huge variety of secondary metabolites with a broad spectrum of use. The endophytic fungus Cochliobolus sp. G2-20, still little known, and can effectively produce bioactive compounds. It was isolated from Sapindus saponaria L., a plant with antimicrobial effects. The aim of this study was to obtain secondary metabolites from the fungus Cochliobolus sp. G2-20 isolated from medicinal plant S. saponaria L., to characterize the main compounds of crude extract of secondary metabolites and to evaluate their antimicrobial activity. The endophytic fungus was grown in potato dextrose broth for 7 days without agitation at a temperature of 28°C. It was used for the filtration followed by centrifugation to the obtainment of broth without mycelium. The supernatant was partitioned with ethyl acetate resulting in an extract that was fractionated and used to identify metabolite compounds. After chromatographic procedures, the fractions were analyzed by 1H (300 MHz) and 13C (75.5 MHz) nuclear magnetic resonance for identification of the chemical components. Curvularin was identified from fraction D being the main substance produced by Cochliobolus sp. G2-20, and had an inhibitory effect on growth of the fungi Moniliophthora perniciosa, Didymella bryoniae, and Fusarium solani forma specialis (f. sp.) glycines, and bacteria Micrococcus luteus, Xanthomonas axonopodis pv. phaseoli, Staphylococcus aureus, Escherichia coli, and Enterococcus hirae. The extract of the endophytic fungus Cochliobolus sp. showed antibacterial and antifungal activities, thus confirming its potential for biotechnological applications.