Puerarin protects against Staphylococcus aureus-induced injury of human alveolar epithelial A549 cells via downregulating alpha-hemolysin secretion.

Alpha-hemolysin, a secreted pore-forming toxin, plays an indispensable role in the pathogenicity of Staphylococcus aureus. In this study, the antimicrobial activity of puerarin against S. aureus was investigated; as a result, puerarin showed no influence on the growth of this organism. However, hemolysis and western blotting assays showed that puerarin concentration dependently inhibited the secretion of alpha-hemolysin at low concentrations. Real-time RT-PCR assay was further employed to evaluate the transcriptional level of hla, the gene encoding alpha-hemolysin, and RNAIII, an effector molecule of the agr system. The results indicated that the RNAIII expression and subsequent hla transcription were also inhibited by puerarin in a dose-dependent manner. Furthermore, puerarin significantly prevented human alveolar epithelial A549 cells from S. aureus-induced injury. Thereby, puerarin may be considered as a potential candidate for the development of antivirulence drugs in the treatment of S. aureus-mediated infections.

The effect of molybdenum on the in vitro development of mouse preimplantation embryos.

The object of this study was to investigate the effect of molybdenum on the development of mouse preimplantation embryos cultured in vitro. Zygotes were flushed from one outbred mouse strain (Kunming), and then were cultured in potassium simplex optimized medium (KSOM) containing 0, 5, 10, 20, 40, 80, 120, and 160 µg/ml of molybdenum for 5 days until the mid-blastocyst stage. The addition of ≤ 20 µg/ml molybdenum did not affect the blastocyst and birth rates. Molybdenum at doses of 40 µg/ml and higher significantly decreased the cleavage, blastocyst and birth rates, the average cell number, and significantly increased the proportion of degenerative blastocysts. At 120 µg/ml molybdenum inhibited the blastocysts development to birth. At 160 µg/ml molybdenum caused overall developmental arrest (up to 16-cells) of embryos and their massive degeneration. In conclusion, molybdenum negatively affected the development of embryos in a dose-dependent manner. With lower doses (≤ 20 µg/ml), mouse embryos were not apparently damaged. With very high doses (≥ 40 µg/ml), embryo quality significantly decreased. This assessment of the effect of molybdenum on the preimplantation embryo is an initial survey of toxicological risk.