Antifungal activity of extracts from Atacama Desert fungi againstParacoccidioides brasiliensis and identification ofAspergillus felis as a promising source of natural bioactive compounds

Fungi of the genus Paracoccidioides are responsible for paracoccidioidomycosis. The occurrence of drug toxicity and relapse in this disease justify the development of new antifungal agents. Compounds extracted from fungal extract have showing antifungal activity. Extracts of 78 fungi isolated from rocks of the Atacama Desert were tested in a microdilution assay against Paracoccidioides brasiliensis Pb18. Approximately 18% (5) of the extracts showed minimum inhibitory concentration (MIC) values≤ 125.0 µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the best results, with an MIC of 15.6 µg/mL. This isolate was identified as Aspergillus felis (by macro and micromorphologies, and internal transcribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and was grown in five different culture media and extracted with various solvents to optimise its antifungal activity. Potato dextrose agar culture and dichloromethane extraction resulted in an MIC of 1.9 µg/mL against P. brasiliensis and did not show cytotoxicity at the concentrations tested in normal mammalian cell (Vero). This extract was subjected to bioassay-guided fractionation using analytical C18RP-high-performance liquid chromatography (HPLC) and an antifungal assay using P. brasiliensis. Analysis of the active fractions by HPLC-high resolution mass spectrometry allowed us to identify the antifungal agents present in the A. felis extracts cytochalasins. These results reveal the potential of A. felis as a producer of bioactive compounds with antifungal activity.

Flavonoids from leaves of Mauritia flexuosa

The chromatographic fractionation of the Mauritia flexuosa L. f., Arecaceae, leaves extract, a plant known by the name of buriti palm tree, resulted in the isolation of six flavonoids: tricin-7-O-rutinoside, apigenin-6-C-arabinoside, 8-C-glucoside (isoschaftoside), kaempferol-3-O-rutinoside (nicotiflorine), quercetin-3-O-rutinoside (rutin), luteolin-8-C-glucoside (orientin) and luteolin-6-C-glucoside (isoorientin). The flavonoids were found out and previously reported as constituents of the Arecaceae family plants, but the occurrence of C-glucoside flavonoids, in the species being analyzed, is described for the first time on this study. The structural elucidations of all of the isolated compounds were performed by means of the comparison of their spectral data (¹H and 13C NMR, UV and ESI-MS) with those ones of the literature.

Chemical constituents and leishmanicidal activity from leaves of Kielmeyera variabilis

Many phenolic compounds such as xanthones, quinones and coumarins have been isolated from Kielmeyera species; however the presence of flavonoids have been showed in other genera in the Calophylleae tribe as Caraipa, Mesua and Calophyllum. Six known glycosidic flavonoids: quercetin 3-β-O-galactopyranoside (1), quercetin 3-β-O-glucopyranoside (2), quercetin 3-O-α-rhamnoside (3), luteolin 6-C-β-glucopyranoside (4), isovitexin (5), kaempferol 3-O-α-rhamnoside (6) and one triterpene, lupenone (7) were isolated, for the first time, from organic crude extract of Kielmeyera variabilis Mart. & Zucc., Calophyllaceae, leaves. The crude organic extract from K. variabilis leaves exhibited 95% of leishmanidal activity at 20 µg/mL on amastigote-like form of Leishmania (Leishmania) amazonensis in vitro model and only compound 3 showed 40-45% of growth inhibition at concentration ranging from 0.78 to 20 µg/mL. In addition, quercetin 3-O-α-rhamnoside (quercitrin) was found to be the major metabolite. Our results and previous reports suggest that synergistic effects of flavonoid glycosides are the cause of significant leishmanidal activity of the crude organic extract from K. variabilis leaves.

Bioactivity of the compounds isolated from Blepharocalyx salicifolius

Blepharocalyx salicifolius (Kunth) O. Berg, Myrtaceae, is an endemic species that occurs at Southern America. This species was studied to intend to isolation of the active compounds that could be used in vitro model against leishmaniosis, tumoral cell and paracoccidioidomycosis. After Gel Permeation Chromatography, the ethanolic extract from leaves yielded sixteen fractions. Five compounds were isolated and assayed, showing activity against tumoral cells, from 3.33 to 12.83 µg.mL-1; Leishmania (Leishmania) amazonensis from 2.19 to 20.80 µg.mL-1 and Paracoccidioides brasiliensis from 3.10 to 12.5 µg.mL-1.