Antifungal Activity of Decyl Gallate against Several Species of Pathogenic Fungi

This work aims to demonstrate that the gallic acid structure modification to the decyl gallate (G14) compound contributed to increase the antifungal activity against several species of pathogenic fungi, mainly, Candida spp., Cryptococcus spp., Paracoccidioides spp., and Histoplasma capsulatum, according to standardized microdilution method described by Clinical Laboratory Standard Institute (CLSI) documents. Moreover this compound has a particularly good selectivity index value, which makes it an excellent candidate for broad-spectrum antifungal prototype and encourages the continuation of subsequent studies for the discovery of its mechanism of action

Perfil fenotípico e de expressão de proteínas de Cryptococcus neoformans após tratamento com substâncias obtidas da planta Pterogyne nitens

A criptococose tem emergido como importante infecção oportunista em pacientes imunossuprimidos e imunocompetentes causando principalmente a neurocriptococose. Cryptococcus neoformans, um dos agentes, é uma levedura capsulada comumente encontrada em infecções do sistema nervoso central em pacientes HIV positivos. No mercado há fármacos para o tratamento dessas infecções, porém problemas são verificados quanto ao espectro de ação, custos e efeitos adversos. As plantas são usadas na medicina por longa data constituindo-se de uma ótima alternativa para busca de substâncias que podem ser utilizadas na formulação de novos antifúngicos. Neste estudo foram avaliados vários extratos, frações e substâncias puras do projeto BIOTA frente à cepa ATCC de C. neoformans, bem como em isolados clínicos com perfil de sensível e resistente frente ao fluconazol. Também foi feita a padronização e aplicação da metodologia do “tabuleiro de xadrez” para verificação de atividade sinérgica, aditiva, indiferente e antagônica entre as frações de plantas de interesse, bem como a molécula pedalitina associada com outras substâncias de origem vegetal e com as drogas sintéticas fluconazol e anfotericina B. Os que apresentaram melhores concentrações inibitórias mínimas...Cryptococcosis is a disease that has emerged as an important opportunistic infection in immunocompromised and immunocompetent patients mainly causing cryptococcal meningitis. Cryptococcus neoformans, one of the agents, is encapsulated yeast most commonly found in central nervous system infections in HIV patients. There are drugs on the marketplace for the treatment of these infections, but problems are related to spectrum of action, costs and adverse effects. Plants are used in medicine for a long time and they are a great alternative to look for substances that can be used to develop new antifungal agents. In this study we evaluated several extracts, fractions and pure substances from BIOTA project against the ATCC strain of C. neoformans, as well as clinical isolates with sensible and resistant profile to fluconazole. The standardization and application of the methodology of the chessboard technique was developed to verify synergistic, additive, indifferent and antagonistic activities among the fractions of the selected plants, and the molecule pedalitin associated with other natural compounds and the synthetic drugs fluconazole and amphotericin B. The substances that presented the best minimum inhibitory concentrations were selected to verify the fungi protein profile before and after contact with the plant substance and adhesion profile to cells (pneumocytes) A549. Among the plants studied, Pterogyne nitens, specie that belongs to the family Fabaceae, which has the active substance called pedalitin, presented a significant antifungal activity against the isolates of C. neoformans including resistant. Suspensions of C. neoformans with and without treatment with fluconazole and in contact with pedalitin were analyzed by SDS-PAGE and two-dimensional electrophoresis. These treatments revealed changes in the expression... (Complete abstract click electronic access below)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Microplate alamarblue assay for paracoccidioides susceptibility testing

CLSI method M27-A3 is not available for use with dimorphic fungi, such as those of the Paracoccidioides genus. In this study, we developed a microdilution method and added the alamarBlue reagent to test the responses of Paracoccidioides brasiliensis and Paracoccidioides lutzii against amphotericin B and itraconazole antifungals. The test proved to be sensitive, practical, and inexpensive and can be used to monitor the activity of low-growth microorganisms and their response to various drugs. © 2013, American Society for Microbiology

Amphotericin B mediates killing in Cryptococcus neoformans through the induction of a strong oxidative burst

We studied the effects of Amphotericin B (AmB) on Cryptococcus neoformans using different viability methods (CFUs enumeration, XTT assay and propidium iodide permeability). After 1 h of incubation, there were no viable colonies when the cells were exposed to AmB concentrations >= 1 mg/L. In the same conditions, the cells did not become permeable to propidium iodide, a phenomenon that was not observed until 3 h of incubation. When viability was measured in parallel using XTT assay, a result consistent with the CFUs was obtained, although we also observed a paradoxical effect in which at high AmB concentrations, a higher XTT reduction was measured than at intermediate AmB concentrations. This paradoxical effect was not observed after 3 h of incubation with AmB, and lack of XTT reduction was observed at AmB concentrations higher than 1 mg/L. When stained with dihydrofluorescein, AmB induced a strong intracellular oxidative burst. Consistent with oxidative damage, AmB induced protein carbonylation. Our results indicate that in C. neoformans, Amphotericin B causes intracellular damage mediated through the production of free radicals before damage on the cell membrane, measured by propidium iodide uptake. (C) 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved

Anti-Candida and anti-Cryptococcus evaluation of 15 non-alkaloidal compounds from Pterogyne nitens

Objective: To evaluate anti-Candida and anti-Cryptococcus activities of 15 non-alkaloidal compounds from Pterogyne nitens Tulasne (Leguminosae), a South American medicinal plant. Methods: Compounds were submitted to antifungal assays, using microdilution method described by Clinical and Laboratory Standards Institute document, with minor modifications. Five species of Candida and two species of Cryptococcus, including clinical isolates were screened. Antifungal activity was expressed by minimum inhibitory concentration (MIC). Amphotericin B and fluconazole were used as standard antifungal drugs. Results: Among tested compounds, six substances presented fungal growth inhibition (MIC < 31.2 μg/mL) [three flavone derivatives (1–3), a glycosylated flavonol derivative (5) and two phenolic acids (10 and 12)]. Sorbifolin (1), exhibited potent antifungal activity, demonstrating MIC value of 3.90 μg/mL against Candida glabrata ATCC 90030, Cryptococcus gattii 118 and fluconazole-resistant clinical isolate of Cryptococcus neoformans var. grubii. Pedalin (2) and nitensoside B (3), two glycosylated flavone derivatives, were active against Cryptococcus neoformans ATCC 90012 (MIC = 7.80 μg/mL). Conclusions: Flavone derivatives from Pterogyne nitens can serve as prototypes for the design and development of innovative anti-Candida and anti-Cryptococcus hits