Antifungal potential of punicalagin against Cryptococcus neoformans species complex.

This study evaluated the antifungal activity and cytotoxicity profile of the ellagitannin punicalagin, a compound extracted from the L. pacari A. St.-Hil (Lythraceae) leaf, against Cryptococcus neoformans species complex. Minimum inhibitory concentrations (MIC) were checked using the broth microdilution method. Minimum fungicidal concentrations (MFC) and time of death were used to confirm the antifungal activity of the compound. The in vitro cytotoxicity of punicalagin was tested in BALB/c3T3 fibroblasts and A549 human lung cancer cell line, while the hemolytic potential was tested on sheep erythrocytes. The morphological changes induced in yeast strains by the presence of punicalagin were also analyzed. Tested on eight isolates of the C. neoformans complex punicalagin showed MIC of 0.5 to 4.0 µg/mL and MFC> 256 µg/mL. Punicalagin also demonstrated a good growth inhibitory activity in time-kill curves, but it was not able to achieve a statistically significant reduction of fungal growth suggesting a fungistatic effect of the compound. In vitro cytotoxicity studies using the two cell lines showed that punicalagin has low activity on these cells and no activity on sheep erythrocytes. Morphological changes were seen in the yeasts strains studied when treated with punicalagin. Therefore, punicalagin is a potential antifungal for important pathogenic yeasts and presents a low cytotoxicity profile associated with no hemolytic effects.

Effects of the essential oil of Thymus vulgaris L. Against Cryptococcus neoformans

Cryptococcus neoformans is an encapsulated yeast found in the environment, responsible for causing of meningoencephalitis in patients with a compromised immune system. In Brazil, cryptococcosis is the second cause of death among systemic mycoses. The limited efficacy of the available antifungal drugs used in its treatment has encouraged the search for therapeutic alternatives, such as medicinal plants. Thymus vulgaris, popularly known as thyme, is an aromatic plant whose essential oil (EO) possesses antifungal properties. The aim of this study was to assess the action of T. vulgaris EO on C. neoformans clinical isolates. This oil was analyzed by gas chromatography/mass spectrometry (GC/MS), which showed that its main components were thymol, ρ-cymene and linalool. Microdilution broth tests showed that this EO was effective against fungal isolates, with minimum inhibitory concentrations (MICs) ranging from 32 to 128 µg/mL. In vitro interaction tests between this oil and fluconazole (FCZ) showed no potentiation of the antifungal action of this drug. Its effect on mitochondrial metabolism of fungal cells was also evaluated and results demonstrated alterations on the mitochondrial enzyme activity of fungal cells only at concentrations >1,024 µg/mL. The results of the action of this EO on human erythrocytes indicated that it has low cytotoxic activity at MIC values. This investigation describes the antifungal action of T. vulgaris, showing its potential in the development of alternatives in the treatment of C. neoformans

Pimenta pseudocaryophyllus inhibits virulence factors and promotes metabolic changes in Candida yeast.

INTRODUCTION: This is the first study to examine the in vitro susceptibility and the expression of virulence factors in Candida species in the presence of Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae), a Brazilian plant known as paucravo. Additionally, the mechanisms of action of the crude ethanol extract and the ethyl acetate and aqueous fractions of this plant were investigated. METHODS: The in vitro susceptibility of Candida was tested using the broth microdilution method, whereas an XTT reduction assay was used for biofilms. Adherence was determined by counting the number of yeast cells that adhered to 100 oral epithelial cells, and hyphal formation was verified in the hyphal induction medium M199. Flow cytometry with propidium iodide and FUN-1 was performed to assess the mechanism of action. RESULTS: The results revealed that the crude ethanol extract and the ethyl acetate and aqueous fractions of P. pseudocaryophyllus inhibited the growth of Candida isolates at a minimal inhibitory concentration (MIC) ranging from 64 to 256 µg/mL, whereas the 50% sessile minimal inhibitory concentration (SMIC50) ranged from 512 to >1,024 µg/mL. Adherence and hyphal formation were significantly reduced in the presence of the crude ethanol extract and both fractions. Although cell membrane injury was detected, the predominant mechanism of action appeared to be the alteration of yeast metabolism, as demonstrated by flow cytometry. CONCLUSIONS: Our results indicated that antifungal activity reduced the expression of virulence factors in yeast via the alteration of yeast metabolism, suggesting that the crude extract of P. pseudocaryophyllus and its fractions may contain novel antifungal agents.

Pimenta pseudocaryophyllus inhibits virulence factors and promotes metabolic changes in Candida yeast

Introduction This is the first study to examine the in vitro susceptibility and the expression of virulence factors in Candida species in the presence of Pimenta pseudocaryophyllus (Gomes) L.R. Landrum (Myrtaceae), a Brazilian plant known as paucravo. Additionally, the mechanisms of action of the crude ethanol extract and the ethyl acetate and aqueous fractions of this plant were investigated. Methods The in vitro susceptibility of Candida was tested using the broth microdilution method, whereas an XTT reduction assay was used for biofilms. Adherence was determined by counting the number of yeast cells that adhered to 100 oral epithelial cells, and hyphal formation was verified in the hyphal induction medium M199. Flow cytometry with propidium iodide and FUN-1 was performed to assess the mechanism of action. Results The results revealed that the crude ethanol extract and the ethyl acetate and aqueous fractions of P. pseudocaryophyllus inhibited the growth of Candida isolates at a minimal inhibitory concentration (MIC) ranging from 64 to 256µg/mL, whereas the 50% sessile minimal inhibitory concentration (SMIC50) ranged from 512 to >1,024µg/mL. Adherence and hyphal formation were significantly reduced in the presence of the crude ethanol extract and both fractions. Although cell membrane injury was detected, the predominant mechanism of action appeared to be the alteration of yeast metabolism, as demonstrated by flow cytometry. Conclusions Our results indicated that antifungal activity reduced the expression of virulence factors in yeast via the alteration of yeast metabolism, suggesting that the crude extract of P. pseudocaryophyllus and its fractions may contain novel antifungal agents. .