RESUMO
INTRODUCTION: Aqueous and ethanolic extracts of Cajanus cajan (Fabaceae) were examined in vitro for their antiviral activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2). MATERIALS AND METHODS: The antiviral activity was determined using a plaque reduction assay. The cytotoxic concentration (CC50) as well as the inhibitory concentration (IC50) of the extracts was determined from dose-response curves. RESULTS: All extracts tested revealed a high antiviral activity against cell-free HSV-1 and HSV-2. The most active one was the Cajanus ethanol extract with IC50 values of 0.022 microg/ml for HSV-1 and 0.1 microg/ml for HSV-2. In order to identify the mode of antiviral action, the extracts were added to the host cells or viruses at different stages of infection. HSV-1 and HSV-2 were considerably inactivated when the viruses were pretreated with the extracts for 1 h prior to cell infection. At maximum non-cytotoxic concentrations of the extracts, plaque formation was significantly reduced by 95-99% for HSV-1 and HSV-2. In a time-dependent assay with cell-free HSV-1 over a period of 2 h, a clearly time-dependent effect was demonstrated whereby the Cajanus ethanol extract revealed a much higher activity than the Cajanus aqueous one. CONCLUSION: The results obtained indicate that the extracts affect HSV before cell adsorption, but have no effect on the intracellular virus replication. According to our findings, a therapeutic application of Cajanus ethanolic extracts containing crème or ointment as antiviral agent in recurrent HSV infection appears to be promising.
Assuntos
Antivirais/farmacologia , Cajanus/química , Etanol/química , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 2/efeitos dos fármacos , Extratos Vegetais/farmacologia , Água/química , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Herpes Simples/tratamento farmacológico , Concentração Inibidora 50 , Extratos Vegetais/toxicidade , Fatores de TempoRESUMO
We propose a new method for calculating optical defect levels and thermodynamic charge-transition levels of point defects in semiconductors, which includes quasiparticle corrections to the Kohn-Sham eigenvalues of density-functional theory. Its applicability is demonstrated for anion vacancies at the (110) surfaces of III-V semiconductors. We find the (+/0) charge-transition level to be 0.49 eV above the surface valence-band maximum for GaAs(110) and 0.82 eV for InP(110). The results show a clear improvement over the local-density approximation and agree closely with an experimental analysis.
