Anti-inflammatory and antibacterial activities of P. petiolosa (Christ) Ching ethyl acetate extract against S. aureus in mice.

P. petiolosa as a typical Chinese herbal medicine has been generally utilized as Chinese native medicine formulation for treatment of chronic bronchitis, bronchial asthma and pneumoconiosis. The objective of this study was to evaluate the anti-inflammatory and antibacterial activities of P. petiolosa ethyl acetate extract (PPEAE) against S. aureus in mice. The air-dried leaves were extracted with ethyl acetate, mice were infected pneumonia by S. aureus. Colonization of S. aureus in lung tissue was calculated by plate colony count. The number of white blood cells (WBC) in blood was measured by blood cell automatic analyzer. The histopathological analysis of hematoxylin-eosin staining (H&E) of lung tissue was observed under microscope. Real-time PCR assay was employed to determine the relative mRNA expression of HO-1, iNOS and TNF-α. The results showed that, compared with control, after treated with PPEAE the wet/dry (W/D) weight ratio of mice lung tissue (decreased from 5.371 to 4.9) and the number of white blood cells (WBC) (decreased by 3.13×109/mL) decreased dramatically. The number of S. aureus was significantly reduced (from 1.93×105 CFU/mL to 26×103 CFU/mL) in lung tissue after treated with PPEAE. Furthermore, H&E staining showed that PPEAE obviously relieved the inflammation of lung tissue of infected mice. Meanwhile, real-time PCR results indicated that PPEAE down regulated the expression of inflammatory iNOS, TNF-α mRNA and up regulated the expression of anti-inflammatory HO-1 mRNA. In summary, this study revealed that application of crude product PPEAE had prominent antibacterial activity against S. aureus. PPEAE significantly reduced the biomass of S. aureus in lung tissue and effectively relieved the inflammation of S. aureus-induced pneumonia.