RESUMO
The acaricidal activity of trans-cinnamaldehyde was evaluated in vitro on Psoroptes cuniculi. In this study, different concentrations of trans-cinnamaldehyde were tested, and the observed mites mortality was compared with that observed in untreated and treated (Acacerulen R®) controls. The morphological changes in P. cuniculi treated with trans-cinnamaldehyde were examined with light microscopy. By the analysis of variance one-way test, up to 8 µg/ml of trans-cinnamaldehyde gave highly significant (P < 0.01) percentages of mite mortality compared with the untreated controls, but only up to 256 µg/ml, it showed the same efficacy of Acacerulen R®. At the same time, a bioassay was conducted by exposing mites to varying doses of trans-cinnamaldehyde in vitro cultures. The resulting data were analyzed by using a time-dose-mortality modeling technique, yielding the parameters for time and dose effects of P. cuniculi. The ß value was 2.01, indicating that trans-cinnamaldehyde had a good activity to kill P. cuniculi adults. Based on the time-dose-mortality relationships fitted and the virulence indices estimated, trans-cinnamaldehyde is a promising microbial agent for mites control.
Assuntos
Acaricidas/farmacologia , Acroleína/análogos & derivados , Extratos Vegetais/farmacologia , Óleos de Plantas/farmacologia , Psoroptidae/efeitos dos fármacos , Acroleína/farmacologia , Animais , Cassia/química , Infestações por Ácaros/tratamento farmacológico , Extratos Vegetais/química , Óleos de Plantas/química , Controle de Ácaros e Carrapatos/métodosRESUMO
Sodium houttuyfonate (SH), an addition compound of sodium bisulfite and houttuynin, showed in vitro antibacterial activity against 21 Staphylococcus aureus (S. aureus) strains grown in planktonic cultures. Microarray results showed decreased levels of autolysin atl, sle1, cidA and lytN transcripts in the SH-treated strain as compared to the control strain, consistent with the induction of the autolytic repressors lrgAB and sarA and with the downregulation of the positive regulators agrA and RNAIII. Triton X-100-induced autolysis was significantly decreased by SH in S. aureus ATCC 25923, and quantitative bacteriolytic assays and zymographic analysis demonstrated SH-mediated reduction of extracellular murein hydrolase activity in these cells. Anti-biofilm assay showed that SH is poorly active against S. aureus grown in biofilm cultures, whereas SH diminished the amounts of extracellular DNA (eDNA) of S. aureus in a dose-dependent manner, which suggested that SH may impede biofilm formation by reducing the expression of cidA to inhibit autolysis and eDNA release in the early phase. Some of the microarray results were confirmed by real-time RT-PCR.