RESUMO
Candida albicans is a major fungal pathogen in humans. In our previous study, we reported that an ethanol extract from Aucklandia lappa weakens C. albicans cell wall by inhibiting synthesis or assembly of both (1,3)-ß-D-glucan polymers and chitin. In the current study, we found that the extract is involved in permeabilization of C. albicans cell membranes. While uptake of ethidium bromide (EtBr) was 3.0% in control cells, it increased to 7.4% for 30 min in the presence of the A. lappa ethanol extract at its minimal inhibitory concentration (MIC), 0.78 mg/ml, compared to uptake by heat-killed cells. Besides, leakage of DNA and proteins was observed in A. lappa-treated C. albicans cells. The increased uptake of EtBr and leakage of cellular materials suggest that A. lappa ethanol extract induced functional changes in C. albicans cell membranes. Incorporation of diphenylhexatriene (DPH) into membranes in the A. lappa-treated C. albicans cells at its MIC decreased to 84.8%, after 60 min of incubation, compared with that of the controls, indicate that there was a change in membrane dynamics. Moreover, the anticandidal effect of the A. lappa ethanol extract was enhanced at a growth temperature of 40°C compared to that at 35°C. The above data suggest that the antifungal activity of the A. lappa ethanol extract against C. albicans is associated with synergistic action of membrane permeabilization due to changes in membrane dynamics and cell wall damage caused by reduced formation of (1,3)-ß-D-glucan and chitin.
Assuntos
Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos dos fármacos , Saussurea/química , Candidíase , Membrana Celular/efeitos dos fármacos , Membrana Celular/microbiologia , Parede Celular/efeitos dos fármacos , Quitina/metabolismo , Glucanos/metabolismo , Testes de Sensibilidade Microbiana , Extratos Vegetais/farmacologia , TemperaturaAssuntos
Gangrena Gasosa/etiologia , Ferimentos e Lesões/complicações , Anaerobiose , Antibacterianos/uso terapêutico , Membrana Celular/microbiologia , Clostridium perfringens/isolamento & purificação , Dextranos/uso terapêutico , Gangrena Gasosa/tratamento farmacológico , Gangrena Gasosa/terapia , Humanos , Oxigenoterapia Hiperbárica , Peso Molecular , Infecção da Ferida Cirúrgica/complicações , Ferimentos e Lesões/microbiologiaAssuntos
Modelos Biológicos , Nicotiana , Plantas Tóxicas , Vírus do Mosaico do Tabaco , Adsorção , Cálcio/farmacologia , Radioisótopos de Carbono , Fracionamento Celular , Membrana Celular/microbiologia , Centrifugação com Gradiente de Concentração , Concentração de Íons de Hidrogênio , Cinética , Ornitina , Peptídeos/farmacologia , Extratos Vegetais , Cloreto de Sódio/farmacologia , Dodecilsulfato de Sódio/farmacologia , Sonicação , Tensoativos/farmacologia , Vírus do Mosaico do Tabaco/efeitos dos fármacos , Tripsina/farmacologia , Proteínas ViraisRESUMO
Structural alterations induced in HeLa cells by herpes simplex virus and the mechanism whereby the virus is formed in the nucleus in crystal arrays were studied by electron microscopy with both the usual and negatively stained sections. Aggregates of granular and filamentous material were observed in the cytoplasm of infected cells with both sections. On the other hand, no remarkable alterations in appearance of the cytoplasmic ground substance were observed with the usual sections of infected cells. However, the cytoplasmic ground substance of infected cells when negatively stained consisted of granular material which was different in appearance from the spongy material constituting the cytoplasmic matrix of uninfected cells. In the nucleus of infected cells, complexes consisting of round bodies, amorphous material, aggregates of uniform granules in rows, and viral crystals were often observed near the nuclear membrane in both types of sections. Examinations of the granular aggregates with negatively stained sections suggested that each granule represents a subunit and that the several adjoining subunits (approximately eight) constitute the requirement for formation of a single viral capsid with a core. Thus, rapid and simultaneous formation of the core and capsid within the aggregate would replace the rows of the granules with the viral crystal. The advantages of negative staining of thin sections for visualization of fine structural alterations are discussed.