Esteroide, alcaloides e atividade biológica de fungos endofíticos de Palicourea corymbifera (Rubiaceae)

Abstract

This work describes the screening performed with 32 endophytic fungi from leaves of the plant species Palicourea corymbifera in order to select fungi of interest for the production of substances with biotechnological applications. Seventeen morphotypes grown on Sabouraud agar (AS) and 15 on potato dextrose agar (AB) were isolated. At first, a chemical selection was performed for the presence of relevant metabolites. Fungi grown in AS were grown in Sabouraud liquid medium and those isolated in AB were grown in potato liquid medium, both media added with 0.2% yeast extract (EL). Mycelia extracts and broths were chemically evaluated by comparative thin layer chromatography (TLC) and by hydrogen nuclear magnetic resonance (1H NMR). From the result of the chemical screening, 3 fungi coded as SBPC15, SBPC16 and BDPC15 were selected. In order to be identified and to increase the production of biomass. These three fungi were cultivated under the same conditions of temperature (30 °C), time (20 days) and agitation (orbital shaker 120 rpm). Where the difference was in terms of the culture media used. The SBPC15 fungus was grown in Sabouraud broth with 0.2% yeast extract. The SBPC16 fungus was grown in Sabouraud broth with 0.2% yeast extract, and in a liquid medium containing glucose, yeast extract and peptone. The BDPC15 fungus was cultivated in potato broth added with 0.2% yeast extract and Sabouraud broth added with 0.2% yeast extract. The EtOAc extract from the fungus broth (SBPC15) was fractionated and the substances were obtained; tyramine (I) and cycle Proline Tyrosine (II). For the fungus BDPC15 cultivated in liquid potato medium, both the fractionation of the DCM extract from the broth and the mycelium DCM extract resulted in the substance cytochalasin D (III). cytochalasin D (III) was also obtained from the aforementioned fungus cultivated in Sabouraud liquid medium. For the SBPC16 fungus cultivated in Sabouraud, fractionation of the EtOAc extract of mycelium resulted in the substance indole acetamide (IV). Still from SBPC 15 cultivated in liquid medium containing glucose, yeast extract and peptone, the MeOH extract of mycelium was submitted to a liquid/liquid partition, from the fractionation of the EtOAc phase the substance ergosterol (V) was obtained. Part of the mycelia extracts (DCM, EtOAc and MeOH) and broth extracts (DCM and EtOAc) as well as the isolated substances were submitted to bioassays regarding activities; antimicrobial by microdilution in broth, angiogenic assay by the chorioallantoic membrane method and phytotoxicity. The selected fungi were identified as to their taxonomy as being: Xylaria sp. 1 (SBPC15), Xylaria sp. 2 (BDPC15) and Colletotrichum dianesei (SBPC15). In the antimicrobial assay, the extracts of the fungus Xylaria sp.1 four bacteria were sensitive; Acinetobacter baumani, Edwardsiella tarda, Salmonella enteritidis, Staphylococcus aureus, and a fungus; Candida albicans. For the fungus Colletotrichum dianesei, the extracts showed activity against five pathogenic bacteria: Acinetobacter baumani, Edwardsiella tarda, Pseudomonas fluorescens, Salmonella enteritidis, Staphylococcus aureus. For antimicrobial testing with substances: cytochalasin D and ergosterol, none showed growth inhibitory activity against the evaluated strains. In the phytotoxicity test, the extracts of the fungus Xylaria sp. 1, promoted a reduction in the speed of germination and growth of Lactuca sativa. In the approach using substances, cytochalasin D caused root necrosis in L. sativa. In the angiogenesis activity assay, indole acetamide showed antiangiogenic activity. The results of this research reinforce the biotechnological potential of endophytic fungi from the Amazon. This fact has been proven by obtaining substances, some with commercial reality already established and others that can be prototype molecules for the production of other chemical structures with possible bioactivity.