Protozoan parasites belonging to genera Leishmania and Trypanosoma are the etiological agents of severe neglected tropical diseases (NTDs) that cause enormous social and economic impact in many countries of tropical and sub-tropical areas of the world. In our screening program for new drug leads from natural sources, we found that the crude extract of the endophytic fungus Cochliobolus sp. (UFMGCB-555) could kill 90% of the amastigote-like forms of Leishmania amazonensis and inhibit by 100% Ellman's reagent reduction in the trypanothione reductase (TryR) assay, when tested at 20 µg mL−1. UFMGCB-555 was isolated from the plant Piptadenia adiantoides J.F. Macbr (Fabaceae) and identified based on the sequence of the internally transcribed spacer (ITS) regions of its ribosomal DNA. The chromatographic fractionation of the extract was guided by the TryR assay and resulted in the isolation of cochlioquinone A and isocochlioquinone A. Both compounds were active in the assay with L. amazonensis, disclosing EC50 values (effective concentrations required to kill 50% of the parasite) of 1.7 µM (95% confidence interval = 1.6 to 1.9 µM) and 4.1 µM (95% confidence interval = 3.6 to 4.7 µM), respectively. These compounds were not active against three human cancer cell lines (MCF-7, TK-10, and UACC-62), indicating some degree of selectivity towards the parasites. These results suggest that cochlioquinones are attractive lead compounds that deserve further investigation aiming at developing new drugs to treat leishmaniasis. The findings also reinforce the role of endophytic fungi as an important source of compounds with potential to enter the pipeline for drug development against NTDs.

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BackgroundThe aim of this study was to isolate and identify the antifungal compounds from the extracts of Schinus terebinthifolius (Anacardiaceae) against clinical isolates of the pathogenic fungus Paracoccidioides brasiliensis.MethodsThe hexane and dichlomethane fractions from leaves and stems of S. terebinthifolius were fractionated using several chromatography techniques to afford four compounds.ResultsThe compounds isolated from S. terebinthifolius were identified as schinol (1), a new biphenyl compound, namely, 4'-ethyl-4-methyl-2,2',6,6'-tetrahydroxy[1,1'-biphenyl]-4,4'-dicarboxylate (2), quercetin (3), and kaempferol (4). Compounds 1 and 2 were active against different strains of P. brasiliensis, showing a minimal inhibitory concentration value against the isolate Pb B339 of 15.6 μg/ml. The isolate Pb 1578 was more sensitive to compound 1 with a MIC value of 7.5 μg/ml. Schinol presented synergistic effect only when combined with itraconazole. The compounds isolated from S. terebinthifolius were not able to inhibit cell wall synthesis or assembly using the sorbitol assay.ConclusionThis work reveals for the first time the occurrence of compound 2 and discloses activity of compounds 1 and 2 against several clinical isolates of P. brasiliensis. These results justify further studies to clarify the mechanisms of action of these compounds.

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Parasitic protozoan species belonging to the genera Trypanosoma and Leishmania are the etiological agents of several diseases in tropical areas of the world, for which there is an urgent need for effective and affordable treatment. In this regard, we are screening the Brazilian biodiversity, especially its flora and mycota, for natural products that could serve as leads for drug development against these diseases. Trypanothione reductase (TR) is an enzyme involved in the protection of Trypanosoma and Leishmania species against oxidative stress, and is considered to be a validated drug target. The endophytic fungus Alternaria sp. (UFMGCB55) was isolated from the plant Trixis vauthieri DC (Asteraceae), known to contain trypanocidal compounds. The organic extract of the culture of Alternaria sp. was able to inhibit TR by 99%, when tested at 20 microg mL(-1). Fractionation of the extract identified altenusin, a biphenyl derivative with an IC50 value of 4.3+/-0.3 microM in the TR assay. This compound is the first in its class to have shown TR inhibitory activity, opening new perspectives for the design of more effective derivatives that could serve as drug leads for new chemotherapeutic agents to treat trypanosomiasis and leishmaniasis.

Aiming to identify new sources of bioactive secondary metabolites, we isolated 82 endophytic fungi from stems and barks of the native Brazilian tree Caesalpinia echinata Lam. (Fabaceae). We tested their ethyl acetate extracts in several in vitro assays. The organic extracts from three isolates showed antibacterial activity against Staphylococcus aureus and Escherichia coli [minimal inhibitory concentration (MIC) 32-64 μg/mL]. One isolate inhibited the growth of Salmonella typhimurium (MIC 64 μg/mL) and two isolates inhibited the growth of Klebsiella oxytoca (MIC 64 μg/mL), Candida albicans and Candida tropicalis (MIC 64-128 μg/mL). Fourteen extracts at a concentration of 20 μg/mL showed antitumour activities against human breast cancer and human renal cancer cells, while two isolates showed anti-tumour activities against human melanoma cancer cells. Six extracts were able to reduce the proliferation of human peripheral blood mononuclear cells, indicating some degree of selective toxicity. Four isolates were able to inhibit Leishmania (Leishmania) amazonensis and one isolate inhibited Trypanosoma cruzi by at least 40% at 20 μg/mL. The trypanocidal extract obtained from Fusarium sp. [KF611679] culture was subjected to bioguided fractionation, which revealed beauvericin as the compound responsible for the observed toxicity of Fusarium sp. to T. cruzi. This depsipeptide showed a half maximal inhibitory concentration of 1.9 μg/mL (2.43 μM) in a T. cruzi cellular culture assay.

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Uma nova substância, denominada habenariosídeo {[(2R)-2-[(2,3,4,6-tetra-O-acetil-b-Dglicopiranosil)oxi]-2-(2-metilpropil)-1,4-dioxo-1,4-butanodiil]bis(oximetileno-4,1-fenileno) bis-b-D-glicopiranosídeo}, foi isolada das frações polares do extrato etanólico de Habenaria petalodes Lindl. (Orchidaceae), juntamente com duas substâncias conhecidas e estruturalmente relacionadas, a loroglossina e a militarina. Os flavonóides: isoquercitrina, isorramnetina 3-O-b-D-glicopiranosídeo e isorramnetina 3,7-di-O-b-D-glicopiranosídeo, também foram isolados. As estruturas do habenariosídeo e das demais substâncias foram determinadas pela análise dos dados de EM, IV, UV e RMN mono e bidimensional e comparação com os dados publicados na literatura. IntroductionThe Brazilian flora is exceedingly rich and comprises more than 56,000 endemic plant species. Among the 22,000 members of the family Orchidaceae that have been described worldwide, approximately 1,800 grow endemically in Brazil. 1 In spite of its size and diversity when compared with other plant families, a relatively small number of orchid species have been investigated regarding their chemical composition, with about 300 secondary metabolites reported so far. These included, among others, flavonoids, terpenoids, quinones, phenanthrenes, stilbenes, lignans, and glucosylated benzyl esters of succinic, malic, tartaric and citric acids. [2][3][4][5][6] The phytochemical investigations of Brazilian Orchidaceae are also restricted to few published works: a report concerning the presence of methylated C-glycosylflavones as taxonomic markers in fifteen orchids, 7 and the investigation of the floral composition of other twenty-one species. 8 The genus Habenaria (Orchidaceae) comprises over 600 species of which around 170 occur in Brazil. 9 However, to the best of our knowledge only Habenaria repens Nutt. was chemically investigated so far, resulting in the identification of habenariol, a compound with potent feeding deterrent activity. [10][11][12] In the present paper we report the first phytochemical investigation of Habenaria petalodes Lindl., describing the isolation and structure elucidation of six compounds (1-6), including a new 2-malic acid derivative (4) denominated habenarioside. Cota et al. 1099 Vol. 19, No. 6, 2008 Results and DiscussionThe whole plant was extracted by maceration with ethanol and the extract was subjected to liquid-liquid partition between CH 2 Cl 2 and MeOH:H 2 O (1:1) to afford an organic and a hydroalcoholic fraction. The latter was subjected to solid phase extraction (SFE) using RP-18 cartridges followed by semi-preparative RP-HPLC to yield six compounds (Figure 1-2).The ESI-MS of compounds 1 and 5 exhibited quasimolecular ion peaks ([M + Na] + ) at m/z 765 and m/z 749, respectively. Their molecular weight, together with their UV, 1 H and 13 C NMR data were in accordance with those reported for loroglossin (1) and militarin (5). 5,14 Habenarioside (4) which was given the trivial name habenarioside as it is a mono-glucosylated derivative of hab...