Bauhinia guianensis is a typical plant in the Amazon region belonging to the family Leguminosea, used by local populations for the treatment of infectious and renal diseases. Previous work on the plant B. guianensis led to the isolation of substances with anti-inflammatory and analgesic activities. Thus, compounds isolated from B. guianensis with antimicrobial activities had not been identified. Given that there is a possibility of biological activity reported for a given plant being found in the endophytic fungi, we decided to isolate endophytic fungi from B. guianensis and test their antimicrobial activities. The alkaloids known as fumigaclavine C and pseurotin A were isolated by column chromatography and identified by 1D and 2D NMR techniques and mass spectrometry. The alkaloids are first reported as broad-spectrum antibacterial agents with good activity.

The antiproliferative effect of julocrotine, an alkaloid isolated from Croton pullei var. glabrior (Euphorbiaceae), was studied in the macrophage amastigote and promastigote stages of the protozoan Leishmania (L.) amazonensis, which causes cutaneous leishmaniasis in the New World. Julocrotine showed a dose-dependent effect against the amastigote and promastigote forms, where 79 μM julocrotine inhibited promastigote growth by 54%, with an IC50 of 67 μM. To analyze the antiamastigote activity of the drug, murine peritoneal macrophages infected with L. amazonensis promastigotes were treated with different concentrations of julocrotine. An 80% inhibition of amastigote development was observed using 79 μM julocrotine for 72 h, with an IC50 of 19.8 μM. In addition, ultrastructural observation of the parasites showed a significant reduction in the number of amastigotes in the parasitophorous vacuoles and morphological changes in promastigotes, such as swelling of the mitochondrion, chromatin condensation, presence of membranous structures near the Golgi complex, and some vesicle bodies in the flagellar pocket. A colorimetric assay (MTT), which measures cytotoxic metabolic activity, showed that macrophages maintain their viability after treatment with the drug. These results suggest that julocrotine effectively inhibits the growth of parasites and does not have any cytototoxic effects on the host cell.

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Antibiotic resistance results in higher medical costs, prolonged hospital stays and increased mortality and is rising to dangerously high levels in all parts of the world. Therefore, this study aims to search for new antimicrobial agents through bioprospecting of extracts of endophytic fungi from Bauhinia guianensis, a typical Amazonian plant used in combating infections. Seventeen (17) fungi were isolated and as result the methanolic extract of the fungus Exserohilum rostratum showed good activity against the bacteria tested. The polyketide monocerin was isolated by the chromatographic technique, identified by NMR and MS, showing broad antimicrobial spectrum.

The natural compound ravenelin was isolated from the biomass extracts of Exserohilum rostratum fungus, and its antimicrobial, antiplasmodial, and trypanocidal activities were evaluated. Ravenelin was isolated by column chromatography and HPLC and identified by NMR and MS. The susceptibility of Gram-positive and Gram-negative bacteria strains to ravenelin was determined by microbroth dilution assay. Cytotoxicity was evaluated in hepatocarcinoma cells (HepG2) and BALB/c peritoneal macrophages by using MTT. SYBR Green I-based assay was used in the asexual stages of Plasmodium falciparum. Trypanocidal activity was tested against the epimastigote and intracellular amastigote forms of Trypanosoma cruzi. Ravenelin was active against Gram-positive bacteria strains, with emphasis on Bacillus subtilis (MIC value of 7.5 µM). Ravenelin’s antiparasitic activities were assessed against both the epimastigote (IC50 value of 5 ± 1 µM) and the intracellular amastigote forms of T. cruzi (IC50 value of 9 ± 2 µM), as well as against P. falciparum (IC50 value of 3.4 ± 0.4 µM). Ravenelin showed low cytotoxic effects on both HepG2 (CC50 > 50 µM) and peritoneal macrophage (CC50 = 185 ± 1 µM) cells with attractive selectivity for the parasites (SI values > 15). These findings indicate that ravenelin is a natural compound with both antibacterial and antiparasitic activities, and considerable selectivity indexes. Therefore, ravenelin is an attractive candidate for hit-to-lead development.

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Endophytic fungi are fungi that colonize internal tissues of plants. There are few studies of compounds isolated from endophytic fungi of Amazon plants. Thus, the aim this study was the isolation and structural identification of sitosterol (1), stigmasterol (2), sitostenone (3), squalene (4), ergosterol (5) and ergosterol peroxide (6) from fungus Colletotrichum gloeosporioides isolated as endophytic from Virola michelli, a typical Amazon plant, used in folk medicine against skin infection. Compounds were isolated by chromatography column on silica and identified by 1 H and 13 C NMR and MS. The presence of phytosterols in fungi is rare and this is the first report of the isolation of the phytosterols sitosterol, stigmasterol and sitostenone from the genus Colletotrichum. KEYWORDS: Sterols, secondary metabolites, Amazon fungi. Fotoesteróis isolados do fungo endofítico Colletotrichum gloeosporioides (Melanconiaceae) RESUMOFungos endofíticos são fungos que colonizam os tecidos internos das plantas. Existem poucos estudos de compostos isolados de fungos endofíticos de plantas da Amazônia. Assim, o objetivo deste estudo foi o isolamento e identificação estrutural de sitosterol (1), estigmasterol (2), sitostenona (3), esqualeno (4), ergosterol (5) e peroxido de ergosterol (6) do fungo Colletotrichum gloeosporioides isolado como endofítico de Virola michelli, uma planta típica da Amazônia, usada na medicina popular no combate a infecções de pele. Os compostos foram isolados por cromatografia em coluna de sílica e identificados por RMN 1 H e 13 C e EM. A presença de fitoesteróis em fungos é rara e este é o primeiro relato do isolamento dos fitoesteróides sitosterol, estigmasterol e sitostenona do gêreno Colletotrichum. PALAVRAS-CHAVE: Esteróides, metabolitos secundários, fungos da Amazônia. (Melanconiaceae) Phytosterols isolated from endophytic fungus Colletotrichum gloeosporioides

Recebido em 30/4/08; aceito em 18/3/09; publicado na web em 4/8/09 STEROIDS PRODUCED BY Penicillium herquei, AN ENDOPHYTIC FUNGUS ISOLATED FROM THE FRUITS OF Melia azedarach (MELIACEAE). Six compounds comprising the groups of steroids, the ergosterol, the ergosterol peroxide, the cerevisterol, the neociclocitrinols, the ergosta-4,6,8(14),22-tetraen-3-one, the 25-hydroxy-ergosta-4,6,8(14),22-tetraen-3-one, were isolated from Penicillium herquei fungus obtained from Melia azedarach. The structures were identified by spectral methods of RMN 1D and 2D and MS.Keywords: steroids, endophytic fungus, Penicillium. INTRODUÇÃOMicro-organismos endofíticos estão presentes nos tecidos internos das plantas onde esta associação pode ocorrer em nível celular. É estimado que cerca de 80% das plantas são hospedeiras de fungos. 1-3A natureza dessas interações tem despertado o interesse de químicos, bioquímicos e biólogos na tentativa de entender essas associações, que é um fascinante e amplo campo de pesquisa. A colonização das plantas por endofíticos pode ser mediada pelo seu metabolismo secundário. 4 Em geral esses compostos apresentam atividades antimicrobianas e inseticidas, e sua produção pode ser uma forma de proteção da planta hospedeira contra invasões. 1,4 Nosso grupo tem estudado a química de micro-organismos associados a plantas da família Meliaceae. Uma grande coleção de fungos tem sido isolada das folhas, frutos, raiz e caule de Melia azedarach. 5Algumas espécies de Penicillium isoladas dessa planta têm produzido metabólitos secundários interessantes pela sua química e atividade biológica.6 Este artigo descreve o estudo químico de P. herquei, cultivado em arroz, o isolamento e identificação de esteroides. RESULTADOSAs substâncias 1, 2 e 3 foram obtidas da fase diclorometânica do extrato metanólico da biomassa produzida por P. herquei cultivado em arroz (Uncle Ben's). Essas substâncias são sólidas cristalinas e seus dados de RMN e EM são perfeitamente coincidentes com os descritos na literatura para o ergosterol (1), peróxido de ergosterol (2) e cerevisterol (3).