Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 36
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Acta Biol Hung ; 68(2): 220-231, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28605977

RESUMO

The present study investigated the linalool (Lol)-induced effects in acute toxicity tests in the human pathogen Candida albicans (C. albicans). Lol treatments induced reduced germ tube formation of the pathogen, which plays a crucial role in the virulence. In comparison with the untreated control, the exposure of 107 cells ml-1 to 0.7 mM or 1.4 mM Lol for one hour induced 20% and 30% decrements, respectively, in the colony-forming ability. At the same time, these treatments caused dose-dependent decrease in the levels of superoxide anion radical and total reactive oxygen species, while there was 1.5 and 1.8-fold increases in the concentrations of peroxides and lipid peroxides, respectively, indicating oxidative stress induction in the presence of Lol. Lol treatments resulted in different adaptive modifications of the antioxidant system. In 0.7 mM-treated cells, decreased specific activities of superoxide dismutase and catalase were detected, while exposure to 1.4 mM Lol resulted in the up-regulation of catalase, glutathione reductase and glutathione peroxidases.


Assuntos
Candida albicans/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Monoterpenos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Peróxidos/metabolismo , Candida albicans/patogenicidade , Relação Dose-Resposta a Droga , Humanos
2.
Apoptosis ; 22(2): 175-187, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27826675

RESUMO

The effects of clary sage (Salvia sclarea L.) oil (CS-oil), and its two main components, linalool (Lol) and linalyl acetate (LA), on cells of the eukaryotic human pathogen yeast Candida albicans were studied. Dynamic and thermodynamic properties of the plasma membrane were investigated by electron paramagnetic resonance (EPR) spectroscopy, with 5-doxylstearic acid (5-SASL) and 16-SASL as spin labels. The monitoring of the head group regions with 5-SASL revealed break-point frequency decrease in a temperature dependent manner of the plasma membrane between 9.55 and 13.15 °C in untreated, in CS-oil-, Lol- and LA-treated membranes. The results suggest a significant increase in fluidity of the treated plasma membranes close to the head groups. Comparison of the results observed with the two spin labels demonstrated that CS-oil and LA induced an increased level of fluidization at both depths of the plasma membrane. Whereas Lol treatment induced a less (1 %) ordered bilayer organization in the superficial regions and an increased (10 %) order of the membrane leaflet in deeper layers. Acute toxicity tests and EPR results indicated that both the apoptotic and the effects exerted on the plasma membrane fluidity depended on the composition and chemical structure of the examined materials. In comparison with the control, treatment with CS-oil, Lol or LA induced 13.0, 12.3 and 26.4 % loss respectively, of the metabolites absorbing at 260 nm, as a biological consequence of the plasma membrane fluidizing effects. Our results confirmed that clary sage oil causes plasma membrane perturbations which leads to cell apoptosis process.


Assuntos
Apoptose/genética , Candida albicans/genética , Membrana Celular/genética , Antifúngicos/farmacologia , Apoptose/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Espectroscopia de Ressonância de Spin Eletrônica , Fluidez de Membrana/efeitos dos fármacos , Monoterpenos/farmacologia , Óleos Vegetais/química , Óleos Vegetais/farmacologia , Salvia/química , Marcadores de Spin
3.
Toxicon ; 111: 100-7, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26752674

RESUMO

The effects of combined treatment with patulin (PAT) and citrinin (CTN) on Schizosaccharomyces pombe cells were investigated in acute toxicity tests. In comparison with the controls the exposure of fission yeast cells (10(7) cells ml(-1)) to PAT + CTN (250 µM each) for 1 h at a survival rate of 66.6% significantly elevated the concentration of total reactive oxygen species (ROS) via increased levels of peroxides without affecting the concentrations of superoxides or the hydroxyl radical. This treatment induced a 3.08-fold increase in the specific concentration of glutathione and elevated specific activities of catalase and glutathione S-transferase, while at the same time the activity of glutathione reductase decreased. The pattern of the ROS was the same as that induced by CTN (Máté et al., 2014), while the presence of PAT in the PAT + CTN combination treatment modified the activities of the antioxidant system (Papp et al., 2012) in comparison with the individual PAT or CTN treatment, suggesting toxin-specific regulation of glutathione and the enzymes of the antioxidant system and the possibility that the transcription factor (pap1 and atf1) -regulated processes might be influenced directly by ROS.


Assuntos
Antioxidantes/metabolismo , Citrinina/farmacologia , Patulina/farmacologia , Schizosaccharomyces/efeitos dos fármacos , Schizosaccharomyces/metabolismo , Citrinina/administração & dosagem , Citrinina/farmacocinética , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Enzimas/genética , Enzimas/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Glutationa/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Proteínas Associadas a Pancreatite , Patulina/administração & dosagem , Patulina/farmacocinética , Peróxidos
4.
Acta Biol Hung ; 66(3): 326-38, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26344028

RESUMO

The wild-type viral protein R (Vpr) of human immunodeficiency virus type 1 exerts multiple effects on cellular activities during infection, including the induction of cell cycle G2 arrest and the death of human cells and cells of the fission yeast Schizosaccharomyces pombe. In this study, wild-type Vpr (NL4-3Vpr) integrated as a single copy gene in S. pombe chromosome was used to investigate the molecular impact of Vpr on cellular oxidative stress. NL4-3Vpr triggered an atypical response in early (14-h), and a wellregulated oxidative stress response in late (35-h) log-phase cultures. Specifically, NL4-3Vpr expression induced oxidative stress in the 14-h cultures leading, to decreased levels of superoxide anion (O(2)(·-)), hydroxyl radical (·OH) and glutathione (GSH), and significantly decreased activities of catalase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and glutathione S-transferase. In the 35-h cultures, elevated levels of O(2)(·-) and peroxides were accompanied by increased activities of most antioxidant enzymes, suggesting that the Vpr-induced unbalanced redox state of the cells might contribute to the adverse effects in HIV-infected patients.


Assuntos
Cromossomos Fúngicos , HIV-1/genética , Oxirredutases , Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces , Produtos do Gene vpr do Vírus da Imunodeficiência Humana , Cromossomos Fúngicos/genética , Cromossomos Fúngicos/metabolismo , Humanos , Oxirredução , Estresse Oxidativo/fisiologia , Oxirredutases/genética , Oxirredutases/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/metabolismo , Produtos do Gene vpr do Vírus da Imunodeficiência Humana/biossíntese , Produtos do Gene vpr do Vírus da Imunodeficiência Humana/genética
5.
Toxicon ; 90: 155-66, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25128706

RESUMO

In this study, the citrinin (CTN)-induced accumulation of reactive oxygen species (ROS) and the regulation of the activities of antioxidant enzymes were investigated in acute toxicity tests in Schizosaccharomyces pombe. 30% of the CTN was accumulated by the cells in 1000 µM CTN solution. In comparison with the control, exposure of 10(7) cells ml(-1) to 1000 µM CTN for 60 min at pH = 4.5 induced significantly (p < 1%) elevated levels of peroxides and total ROS, but not of superoxide or hydroxyl radicals, while there was a 3-fold increase in the concentration of glutathione. ROS-induced adaptation processes at cell and molecular levels via activation of the redox-sensitive transcription factors Pap1 and (in part) Atf1 resulted in significantly increased specific activities of glutathione peroxidases, glucose-6-phosphate dehydrogenase and glutathione S-transferase and in decreased levels of catalase and glutathione reductase, but no changes were detected in the activities of superoxide dismutases. This treatment caused a G2/M cell cycle arrest and elevated the number of fragmented nuclei, which is one of the markers of apoptosis. Comparison of these results with those for the positive control, 200 µM H2O2, suggested that CTN induced a medium level of oxidative stress.


Assuntos
Citrinina/toxicidade , Estresse Oxidativo , Schizosaccharomyces/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Peróxido de Hidrogênio/metabolismo , Proteínas Associadas a Pancreatite , Espécies Reativas de Oxigênio/metabolismo , Schizosaccharomyces/citologia , Schizosaccharomyces/metabolismo , Fatores de Transcrição/metabolismo
6.
J Basic Microbiol ; 54 Suppl 1: S50-62, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24687861

RESUMO

The molecular mechanism of tert-butyl hydroperoxide (t-BuOOH) elicited cytotoxicity and the background of t-BuOOH sensitivity were studied in the Saccharomyces cerevisiae ergosterol-less gene deletion mutant erg5Δ and its parental strain BY4741. In comparison to BY4741, untreated erg5Δ cells exhibited alterations in sterol and fatty acid compositions of the plasma membrane, as reflected by the inherent amphotericin B resistance, an elevated level (31%) of plasma membrane rigidity and a decreased uptake of glycerol. Surprisingly, the untreated erg5Δ cells exhibited an unbalanced intracellular redox state, accompanied by the continuous upregulation of the antioxidant enzymes Mn superoxide dismutase, catalase, and glutathione S-transferase, which resulted in decreased specific concentrations of superoxide and peroxides and elevated levels of the hydroxyl radical and thiols. The 2.5-fold sensitivity of erg5Δ to t-BuOOH suggested that the oxidative stress adaptation processes of the mutant could not restore the redox homeostasis of the cells and there is an overlap between sterol and redox homeostases. t-BuOOH treatment of both strains induced adaptive modification of the sterol and fatty acid compositions, increased the plasma membrane fluidity and elevated the specific activities of most antioxidant enzymes through specific regulation processes in a strain-dependent manner.


Assuntos
Membrana Celular/efeitos dos fármacos , Membrana Celular/fisiologia , Estresse Oxidativo , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/fisiologia , Estresse Fisiológico , terc-Butil Hidroperóxido/toxicidade , Membrana Celular/química , Sistema Enzimático do Citocromo P-450/genética , Ácidos Graxos/análise , Deleção de Genes , Glicerol/metabolismo , Fluidez de Membrana , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Esteróis/análise
7.
Med Mycol ; 52(2): 140-8, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24004389

RESUMO

The investigation of the antifungal activities of drugs whose primary activities are not related to their antimicrobial potential is in the current forefront of research. Statin compounds, which are routinely used as cholesterol-lowering drugs, may also exert direct antimicrobial effects. In this study, the in vitro antifungal activities of various statins (lovastatin, simvastatin, fluvastatin, atorvastatin, rosuvastatin and pravastatin) were examined against one isolate each of four dermatophyte species (Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis and Microsporum gypseum). Basically, statins were effective in inhibiting all dermatophyte studied, but were particularly active against M. canis and T. mentagrophytes. Fluvastatin and simvastatin were active against all of the tested fungi causing a complete inhibition of their growth at very low concentrations (6.25-12.5 µg/ml). Lovastatin and rosuvastatin had inhibitory effects at higher concentrations (25-128 µg/ml), while atorvastatin and pravastatin proved the less effective. The in vitro interactions between statins and different antifungals (ketoconazole, itraconazole, fluconazole, amphotericin B, nystatin, griseofulvin, terbinafine and primycin) were also investigated using a standard chequerboard broth microdilution method. Synergetic interactions were observed in several cases, most of them were noticed when statins were combined with terbinafine and the different azoles. Some combinations were particularly active (ketoconazole-simvastatin or terbinafine-simvastatin), as they were found to exert synergistic effect against all of the investigated isolates. The other antifungals showed synergistic interactions with statins in only certain cases. These results suggest that statins exert substantial antifungal effects against dermatophyte fungi and they should be promising components in a combination therapy as they can act synergistically with a number of clinically used antifungal agents.


Assuntos
Antifúngicos/farmacologia , Arthrodermataceae/efeitos dos fármacos , Sinergismo Farmacológico , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Microsporum/efeitos dos fármacos , Trichophyton/efeitos dos fármacos , Testes de Sensibilidade Microbiana
8.
J Basic Microbiol ; 54(3): 215-25, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23712692

RESUMO

The one-gene mutant hyd1-190 of the fission yeast Schizosaccharomyces pombe displayed four-fold resistance to tert-butyl hydroperoxide (t-BuOOH) in comparison with its parental strain hyd(+). The cells of hyd1-190 exhibited a quantitative alteration in the sterol content and hence in the fatty acid composition of the plasma membrane, reflected in a two-fold amphotericin B sensitivity, increased rigidity of the plasma membrane, revealed by an elevated (Δ7.9 °C) phase-transition temperature, measured by means of electron paramagnetic resonance spectroscopy, and a significantly decreased uptake of glycerol. Treatment of the strains with a subinhibitory concentration (0.2 mM) of t-BuOOH induced adaptation via modification of the sterol and fatty acid compositions, resulting in increased (Δ3.95 °C) and decreased (Δ6.83 °C) phase-transition temperatures of the hyd(+) and hyd1-190 strains, respectively, in order to defend the cells against the consequences of t-BuOOH-induced external oxidative stress. However, in contrast with hyd(+), hyd1-190 lacks the ability to adapt to t-BuOOH at a cell level.


Assuntos
Membrana Celular/metabolismo , Schizosaccharomyces/metabolismo , terc-Butil Hidroperóxido/metabolismo , Glicerol/metabolismo , Temperatura Alta , Mutação , Transição de Fase , Schizosaccharomyces/efeitos dos fármacos , Schizosaccharomyces/ultraestrutura , terc-Butil Hidroperóxido/toxicidade
9.
Food Chem Toxicol ; 59: 636-42, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23851147

RESUMO

Citrinin (CTN) is a toxic fungal metabolite that is a hazardous contaminant of foods and feeds. In the present study, its acute toxicity and effects on the plasma membrane of Schizosaccharomyces pombe were investigated. The minimum inhibitory concentration of CTN against the yeast cells proved to be 500 µM. Treatment with 0, 250, 500 or 1000 µM CTN for 60 min resulted in a 0%, 2%, 21% or 100% decrease, respectively, in the survival rate of the cell population. Treatment of cells with 0, 100, 500 or 1000 µM CTN for 20 min induced decrease in the phase-transition temperature of the 5-doxylstearic acid-labeled plasma membrane to 16.51, 16.04, 14.18 or 13.98°C, respectively as measured by electron paramagnetic resonance spectroscopy. This perturbation was accompanied by the efflux of essential K⁺ from the cells. The existence of an interaction between CTN and glutathione was detected for the first time by spectrofluorometry. Our observations may suggest a direct interaction of CTN with the free sulfhydryl groups of the integral proteins of the plasma membrane, leading to dose-dependent membrane fluidization. The change in fluidity disturbed the ionic homeostasis, contributing to the death of the cells, which is a novel aspect of CTN cytotoxicity.


Assuntos
Antifúngicos/farmacologia , Membrana Celular/efeitos dos fármacos , Citrinina/farmacologia , Fluidez de Membrana/efeitos dos fármacos , Schizosaccharomyces/efeitos dos fármacos , Antifúngicos/química , Antifúngicos/metabolismo , Membrana Celular/química , Permeabilidade da Membrana Celular , Citrinina/química , Citrinina/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Glutationa/química , Glutationa/metabolismo , Testes de Sensibilidade Microbiana , Viabilidade Microbiana , Potássio/análise , Potássio/metabolismo , Protoplastos/química , Protoplastos/efeitos dos fármacos , Schizosaccharomyces/química , Schizosaccharomyces/crescimento & desenvolvimento , Espectrometria de Fluorescência , Temperatura de Transição/efeitos dos fármacos
10.
Toxicon ; 73: 130-43, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23896534

RESUMO

This study investigates the non-estrogenic mode of zearalenone (ZEA) toxicity in a novel aspect via accumulation of reactive oxygen species (ROS) and the regulation of the activities of antioxidant enzymes in the Schizosaccharomyces pombe in acute toxicity tests. In comparison with the control, 500 µM ZEA treatment caused 66% decrease in the concentration of glutathione (GSH), which was a consequence, in the absence of ZEA-GSH interaction, of the GSH-consuming processes of the antioxidant system; this depletion of GSH initiated a 1.8- and 2.0-fold accumulation of the superoxide anion and hydrogen peroxide, but did not increase the concentration of the hydroxyl radical; ROS-induced adaptation processes via activation of the Pap1 transcription factor resulted in significantly increased activities of superoxide dismutases, catalase, glutathione reductase and glutathione S-transferase, and decreased activities of glutathione peroxidase and glucose-6-phosphate dehydrogenase. This treatment altered the sterol composition of the cells by inducing decreased concentrations of ergosterol, squalene and 24-methylene-24,25-hydrolanosterol, and also elevated the number of fragmented nuclei. Cells strived to correct the unbalanced redox state by regulation of the antioxidant system, but this was not enough to defend the cells from the disturbed sterol composition, the cell cycle arrest, and the fragmentation of nuclei.


Assuntos
Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Schizosaccharomyces/metabolismo , Zearalenona/toxicidade , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Núcleo Celular/efeitos dos fármacos , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Testes de Sensibilidade Microbiana , Oxirredução , Proteínas Associadas a Pancreatite , Schizosaccharomyces/efeitos dos fármacos , Esteróis/metabolismo , Superóxidos/metabolismo , Testes de Toxicidade Aguda
11.
J Antibiot (Tokyo) ; 66(2): 67-72, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23168406

RESUMO

The in vitro antifungal activities of the macrolide lactone antibiotic complex primycin (PC) and its main components, A1 (50%), A2 (7.3%) and C1 (13%), against the opportunistic pathogenic fungus Candida albicans 33erg(+)were determined by microdilution testing. The MIC(100) (the minimal concentration required for 100% growth inhibition) values found, A2 (2 µg ml(-1)), PC (32 µg ml(-1)), A1 (32 µg ml(-1)) and C1 (64 µg ml(-1)), suggested that the biological activity of PC is highly dependent on the proportions of its constituents. In vivo measurements of the biophysical properties of plasma membranes were carried out by electron paramagnetic resonance (EPR) spectroscopic methods, using the spin probe 5-(4,4-dimethyloxazolidine-N-oxyl)stearic acid. Conventional EPR measurements demonstrated altered phase transition temperatures (Tm) of the plasma membrane of strain 33erg(+) as a consequence of treatment with PC or its constituents: for cells treated with 128 µg ml(-1) PC, A1, A2 or C1 for 15 min, Tm was 17, 21, 14.5 and 15 °C, respectively; that is significantly higher than the Tm of untreated cells, 12 °C. The molecular motions of the near-surface hydrophobic region of the plasma membrane, estimated by saturation transfer EPR spectroscopy, reflected changes in the membrane phases after the treatment. Two physiological membrane phases were detected in control samples: liquid-ordered and liquid-disordered, characterized by molecular movements ∼10(-6)-10(-8) s and ≥10(-9) s. The cells treated with the investigated compounds showed the strong presence of a non-physiological gel phase additional to the above phases, characterized by movements ≤10(-5) s.


Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Macrolídeos/farmacologia , Antifúngicos/química , Antifúngicos/metabolismo , Candida albicans/isolamento & purificação , Candida albicans/metabolismo , Membrana Celular/química , Macrolídeos/química , Macrolídeos/classificação , Macrolídeos/metabolismo , Testes de Sensibilidade Microbiana
12.
FEMS Yeast Res ; 12(8): 958-68, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22909133

RESUMO

7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT) is an antifungal agent that induces oxidative stress and enhances the activity of other antifungals with different modes of action. A genome-wide screening of Saccharomyces cerevisiae genomic library in the high-copy-number plasmid revealed three genes, YAP1, PDE2, and STB3, which increased the CTBT tolerance of the parental strain. The YAP1 gene is known to activate many genes in response to oxidants. The PDE2 and STB3 genes encode the high-affinity cAMP phosphodiesterase and the transcription factor recognizing the ribosomal RNA processing element in promoter sequences, respectively. The protective effects of their overexpression against CTBT toxicity was observed in the absence of certain proteins involved in stress responses, cell wall integrity signaling, and chromatin remodeling. The enhanced CTBT tolerance of the YAP1, PDE2, and STB3 transformants was a consequence of their high antioxidant enzyme activities at the beginning of CTBT treatment in comparison with that of the parental strain, for that they inactivated the CTBT-induced reactive oxygen species. These results point to the complex interplay among the oxidant sensing, cAMP-protein kinase A signaling, and transcription reprogramming of yeast cells, leading to their better adaptation to the stress imposed by CTBT.


Assuntos
Estresse Oxidativo/efeitos dos fármacos , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Transativadores/genética , Fatores de Transcrição/genética , Triazinas/farmacologia , Antifúngicos/farmacologia , Reprogramação Celular , DNA Fúngico/genética , Tolerância a Medicamentos , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Análise de Sequência com Séries de Oligonucleotídeos , Espécies Reativas de Oxigênio , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Análise de Sequência de DNA , Transdução de Sinais , Transativadores/metabolismo , Fatores de Transcrição/metabolismo
13.
Food Chem Toxicol ; 50(10): 3792-8, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22796319

RESUMO

Patulin (PAT), is one of the most widely disseminated mycotoxins found in agricultural products. In this study the PAT-induced accumulation of reactive oxygen species (ROS) and the regulation of the specific activities of antioxidant enzymes were investigated in the single cell eukaryotic organism Schizosaccharomyces pombe. In comparison with the untreated cells, 500 µM PAT treatment caused a 43% decrease in the concentration of the main intracellular antioxidant, glutathione (GSH); this depletion of GSH initiated a 2.44- and a 2.6-fold accumulation of superoxide anion and hydrogen peroxide, respectively, but did not increase the concentration of hydroxyl radicals; the reduction of ROS-induced adaptation processes via the activation of Pap1 transcription factor resulted in significantly increased specific activities of Cu/Zn superoxide dismutase, catalase and glutathione S-transferase to protect the cells against the ROS-induced unbalanced redox state. However, no change was measured in the activities of glutathione reductase, glutathione peroxidase and glucose-6-phosphate dehydrogenase. It seems reasonable to assume that the temporary PAT-induced ROS accumulation plays a crucial role in adaptation processes. The adverse effects of PAT may be exerted mainly through the destruction of cellular membranes and protein/enzyme functions.


Assuntos
Estresse Oxidativo/efeitos dos fármacos , Patulina/toxicidade , Schizosaccharomyces/efeitos dos fármacos , Antioxidantes/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Proteínas Associadas a Pancreatite , Espécies Reativas de Oxigênio , Schizosaccharomyces/citologia , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/metabolismo
14.
J Basic Microbiol ; 52(6): 642-52, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22359238

RESUMO

The fungal mycotoxin patulin is produced by several molds, especially by Aspergillus and Penicillium. The aim of this study was to clarify whether patulin causes alterations in plasma membrane permeability of Schizosaccharomyces pombe lead to cellular shrinkage charateristic to apoptosis or increases cell size indicating necrosis in cells. Transmission and scanning electronmicroscopy revealed that lower concentrations of patulin induced cellular shrinkage and blebbing, higher concentration caused expansion without cellular disruption. Large-scale morphological changes of individual cells were followed by time lapse video microscopy. Patulin caused the elongation and stickiness of cells or rounded up their shapes. To visualize chromatin structures of S. pombe nuclei upon patulin treatment, protoplasts were isolated from S. pombe and subjected to fluorescent microscopy. Chromatin changes in the presence of 50 µM patulin concentration were characterized by elongated nuclei containing sticky fibrillary chromatin and enlarged round shaped nuclei trapped at the fibrillary stage of chromatin condensation. Short (60 min) incubation of S. pombe cells in the presence of high (500 µM) patulin concentration generated patches of condensed chromatin bodies inside the nucleus and caused nuclear expansion, with the rest of chromatin remaining in fibrillary form. Longer (90 min, 500 µM) incubation resulted in fewer highly condensed chromatin patches and in nuclear fragmentation. Although, high patulin concentration increased the size of S. pombe size, it did not lead to necrotic explosion of cells, neither did the fragmented nuclei resemble apoptotic bodies that would have indicated programmed cell death. All these morphological changes and the high rate of cell survival point to rapid adaptation and mixed type of fungistatic effects.


Assuntos
Cromatina/efeitos dos fármacos , Micotoxinas/farmacologia , Patulina/farmacologia , Schizosaccharomyces/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Apoptose/genética , Membrana Celular/efeitos dos fármacos , Membrana Celular/genética , Membrana Celular/metabolismo , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/genética , Núcleo Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Células Cultivadas , Cromatina/genética , Necrose/genética , Necrose/metabolismo , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo
15.
J Antibiot (Tokyo) ; 65(4): 193-6, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22274705

RESUMO

The interaction of the antibiotic primycin with the main fungal sterol, ergosterol, was investigated in vitro in order to monitor the effect of primycin on the fungal plasma membrane at the molecular level. The thermodynamic parameters of complex formation were determined by measuring Rayleigh scattering as a signal sensitive to particle size. The Benesi-Hildebrand method validated the 1 : 1 stoichiometry of the primycin-ergosterol complexes. A very low enthalpy change (ΔH=-1.14 kJ mol(-1)) was measured during the complex formation, which itself cannot be responsible for the molecular association. However, the entropy production (ΔS=29.78 J mol K(-1)) observed during the complex formation can describe the molecular interaction. This effect is probably due to the partial destruction of the solvation shell of the interacting species before the interlinking of the molecules. The results highlight the importance of ergosterol as concerns the mode of effect of primycin in the treatment of fungal infections. As the entropy has a determinant role in the ergosterol-primycin interaction, this interaction exhibits a very high temperature dependence, with the important consequence that the effect exerted by primycin on the cell membranes increases with rising temperature, and the effect is therefore pronounced in fevered bodies.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Candida albicans/efeitos dos fármacos , Ergosterol/química , Ergosterol/metabolismo , Macrolídeos/química , Macrolídeos/farmacologia , Candida albicans/química , Candida albicans/metabolismo , Membrana Celular/química , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Entropia , Simulação de Dinâmica Molecular , Tamanho da Partícula , Espalhamento de Radiação , Espectrometria de Fluorescência
16.
Biochim Biophys Acta ; 1818(1): 42-8, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21978596

RESUMO

The direct interaction of the antibiotic primycin with the plasma membrane was investigated by employing the well-characterized ergosterol-producing, amphotericin B-sensitive parental Candida albicans strain 33erg(+) and its ergosterol-less amphotericin B-resistant plasma membrane mutant erg-2. The growth inhibition concentration in shaken liquid medium was 64 µgml(-1) for 33erg(+) and 128 µgml(-1) for erg-2, suggesting that the plasma membrane composition influences the mode of action of primycin. To determine the primycin-induced changes in the plasma membrane dynamic, electron paramagnetic resonance (EPR) spectroscopy methods were used, the spin-labeled fatty acid 5-(4,4-dimethyloxazolidine-N-oxyl)stearic acid) being applied for the in vivo measurements. The phase transition temperatures of untreated strain 33erg(+) and its mutant erg-2 were 12.5°C and 11°C, respectively. After 128 µgml(-1) primycin treatment, these values increased to 17.5°C and 16°C, revealing a significant reduction in the phospholipid flexibility. Saturation transfer EPR measurements demonstrated that, the rotational correlation times of the spin label molecule for the control samples of 33erg(+) and erg-2 were 60 ns and 100 ns. These correlation times gradually decreased on the addition of increasing primycin concentrations, reaching 8 µs and 1 µs. The results indicate the plasma membrane "rigidizing" effect of primycin, a feature that may stem from its ability to undergo complex formation with membrane constituent fatty acid molecules, causing alterations in the structures of phospholipids in the hydrophobic surface near the fatty acid chain region.


Assuntos
Antibacterianos/química , Candida albicans/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Ergosterol/metabolismo , Macrolídeos/química , Anfotericina B/farmacologia , Antibacterianos/farmacologia , Candida albicans/genética , Candida albicans/metabolismo , Membrana Celular/química , Membrana Celular/metabolismo , Relação Dose-Resposta a Droga , Espectroscopia de Ressonância de Spin Eletrônica , Ergosterol/química , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Deleção de Genes , Genes Fúngicos , Interações Hidrofóbicas e Hidrofílicas , Macrolídeos/farmacologia , Fluidez de Membrana , Transição de Fase , Marcadores de Spin , Temperatura Ambiente
17.
Folia Microbiol (Praha) ; 56(4): 353-9, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21818608

RESUMO

The abc1(-)/coq8(-) gene deletion respiratory-deficient mutant NBp17 of fission yeast Schizosaccharomyces pombe displayed a phenotypic fermentation pattern with enhanced production of glycerol and acetate, and also possessed oxidative stress-sensitive phenotypes to H(2)O(2), menadione, tBuOOH, Cd(2+), and chromate in comparison with its parental respiratory-competent strain HNT. As a consequence of internal stress-inducing mutation, adaptation processes to restore the redox homeostasis of mutant NBp17 cells were detected in minimal glucose medium. Mutant NBp17 produced significantly increased amounts of O(2)•- and H(2)O(2) as a result of the decreased internal glutathione concentration and the only slightly increased glutathione reductase activity. The Cr(VI) reduction capacity and hence the •OH production ability were decreased. The mutant cells demonstrated increased specific activities of superoxide dismutases and glutathione reductase (but not catalase) to detoxify at least partially the overproduction of reactive oxygen species. All these features may be explained by the decreased redox capacity of the mutant cells. Most notably, mutant NBp17 hyperaccumulated yellow CdS.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Cádmio/metabolismo , Deleção de Genes , Glutationa/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Ubiquinona/genética , Testes de Sensibilidade Microbiana , Oxidantes/farmacologia , Oxirredução , Peróxidos/metabolismo , Fenótipo , Schizosaccharomyces/efeitos dos fármacos
18.
Int J Food Microbiol ; 144(3): 480-6, 2011 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-21131081

RESUMO

The anti-yeast activities of four essential oils (EOs) from clary sage, juniper, lemon and marjoram against wild-type isolates of the food-related yeasts Geotrichum candidum, Pichia anomala, Saccharomyces cerevisiae and Schizosaccharomyces pombe in malt extract (ME) medium, apple juice and milk were investigated. Minimal inhibitory concentrations (MICs) for the EOs and their main components were determined and the checkerboard method was used to calculate fractional inhibitory concentration (FIC) indices for the combinations of EOs or components. The most sensitive yeast was S. pombe (MICs of 0.0625-0.125 µl/ml) while G. candidum proved to be the most insensitive (MICs of 0.5-2 µl/ml). In general, the lag phases were lengthened by increasing EO concentrations, while significant reduction of growth rates was obtained only at the highest EO concentrations. The anti-yeast effects of the EOs were good in the acidic pH range optimal for yeasts growth. Combinations of juniper and clary sage EOs resulted in additive effects in the case of S. cerevisiae and G. candidum, but all other combinations showed no interaction. The combination of α-pinene and limonene led to synergism, while the combination of α-pinene with linalool resulted in an additive effect. Cloudy apple juice protected the yeasts against the effect of lemon EO: the lag phases were shorter and the growth rates higher than in clear apple juice. Lemon EO decreased the growth rate of G. candidum in skimmed milk in a dose-independent manner. Our results show that by adding lemon EO to clear apple juice a new, harmonic taste can be achieved and open storage time could be prolonged.


Assuntos
Antifúngicos/farmacologia , Bebidas/microbiologia , Microbiologia de Alimentos , Óleos Voláteis/farmacologia , Leveduras/efeitos dos fármacos , Animais , Meios de Cultura/química , Frutas/microbiologia , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Leite/microbiologia
19.
FEMS Microbiol Lett ; 307(2): 175-84, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20636975

RESUMO

The treatment of opportunistic fungal infections is often difficult as the number of available antifungal agents is limited. Nowadays, there is increasing interest in the investigation of the antifungal activity of nonantifungal drugs, and in the development of efficient antifungal combination therapy. In this study, the in vitro interactions of the effects of various statins (lovastatin, simvastatin, fluvastatin, atorvastatin (ATO), rosuvastatin (ROS) and pravastatin) and various azole antifungals [miconazole, ketoconazole, itraconazole and fluconazole (FLU)] against different opportunistic pathogenic fungi were investigated using a standard chequerboard broth microdilution method. When the investigated strains were sensitive to both compounds of the combination, additive interactions were frequently noticed. Synergistic interactions were observed in many cases when a strain was sensitive only to the azole compound (as in certain combinations with ATO or ROS) or the statin compound (as in certain combinations with FLU). In many combinations with an additive effect, the concentrations of drugs needed for total growth inhibition could be decreased by several dilution steps. Similar interactions were observed when the variability of the within-species sensitivities to some selected drug combinations was investigated.


Assuntos
Antifúngicos/farmacologia , Aspergillus/efeitos dos fármacos , Azóis/farmacologia , Candida/efeitos dos fármacos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Piperazinas/farmacologia , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana , Rhizomucor/efeitos dos fármacos , Especificidade da Espécie
20.
Food Chem Toxicol ; 48(7): 1898-904, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20430061

RESUMO

Patulin is a toxic metabolite produced by various species of Penicillium, Aspergillus and Byssochlamys. In the present study, its effects on the plasma membrane of fission yeast Schizosaccharomyces pombe were investigated. The phase-transition temperature (G) of untreated cells, measured by electron paramagnetic resonance spectrometry proved to be 14.1 degrees C. Treatment of cells for 20 min with 50, 500, or 1000 microM patulin resulted in a decrease of the G value of the plasma membrane to 13.9, 10.1 or 8.7 degrees C, respectively. This change in the transition temperature was accompanied by the loss of compounds absorbing light at 260 nm. Treatment of cells with 50, 500 or 1000 microM patulin for 20 min induced the efflux of 25%, 30.5% or 34%, respectively, of these compounds. Besides its cytotoxic effects an adaptation process was observed. This is the first study to describe the direct interaction of patulin with the plasma membrane, a process which could definitely contribute to the adverse toxic effects induced by patulin.


Assuntos
Membrana Celular/efeitos dos fármacos , Patulina/farmacologia , Schizosaccharomyces/efeitos dos fármacos , Membrana Celular/química , Espectroscopia de Ressonância de Spin Eletrônica , Testes de Sensibilidade Microbiana , Patulina/metabolismo , Schizosaccharomyces/metabolismo , Schizosaccharomyces/ultraestrutura , Temperatura Ambiente
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA