Subinhibitory concentrations of pinocembrin exert anti-Staphylococcus aureus activity by reducing α -toxin expression

Abstract

Aims: Natural products have been used as potentially important sources of novel antibacterials in combating pathogenic Staphylococcus aureus isolates, a major problem around the world. In this study, we aimed to investigate the antibacterial effects of pinocembrin (PNCB) against Staph. aureus pneumonia in a murine model and its influence on the production of Staph. aureus a-haemolysin (Hla). Methods and Results:The in vitro activities of PNCB on a-haemolysin production were determined using haemolysis, Western blot and real-time RT-PCR assays. The viability and cytotoxicity assays were performed to evaluate the influence of PNCB on a-toxin-mediated injury of human alveolar epithelial cells. Moreover, through histopathologic analysis, we further determined the in vivo effects of PNCB on Staph. aureus pneumonia in a mouse model. In vitro, PNCB at low concentrations exhibited inhibitory activity against a-haemolysin production and attenuated a-haemolysinmediated cell injury. Furthermore, the in vivo findings demonstrated that PNCB protected mice from Staph. aureus pneumonia. Conclusions: We have provided new evidence of the effects of PNCB, which suggest that PNCB attenuated a-haemolysin-mediated cell injury and protected mice from Staph. aureus pneumonia. Significance and Impact of the Study: The findings indicate that PNCB may be used as a basis for anti-Staphylococcus agent.

Chitosan-propolis nanoparticle formulation demonstrates anti-bacterial activity against Enterococcus faecalis biofilms

“…faecalis , Staphylococcus epidermidis , S . aureus (methicillin and gentamycin resistant), Bacillus cereus , Escherichia coli , Klebsiella pneumonia , Pseudomonas aeruginosa , Cryptococcus neoformans and Candida albicans [47, 48] and is also reported to inhibit both Gram-positive and Gram-negative bacteria and induce bacterial cell lysis [49]. …”

Antibiofilm and Antioxidant Activity of Propolis and Bud Poplar Resins versus Pseudomonas aeruginosa

“…For example, the stronger activity of propolis extract in reducing TNF- α and IL-1 β secretion and inhibiting ROS production could be due to its higher content in chrysin and galangin compared to bud poplar resins extract, while their comparable antimicrobial activity could reflect their similar content in pinocembrin. Indeed, while chrysin and galangin have been shown to hold effective antioxidant and anti-inflammatory activity [38–42] pinocembrin is considered to possess antimicrobial properties [43, 44]. The similarity in the composition and the activity between both extracts (from propolis and buds) is due to the fact that poplar trees are the source of the propolis sample.…”

Plant Phenolics and Phenolic-Enriched Extracts as Antimicrobial Agents against Food-Contaminating Microorganisms

“…The inhibitory effects of gallotannins may be attributed to their iron-complexing properties and ability to interact with proteins and inhibit enzyme activities [79]. At the same time, flavonoids have a series of antibacterial actions with different mechanisms of action, such as inhibition of nucleic acid synthesis [80], induction of cytoplasmic membrane damage [81,82] and inhibition of energy metabolism [83], biofilm formation [3] and bacterial toxin production [84]. The flavonoid catechin can penetrate the lipid bilayers of the membrane resulting in leakage of intramembranous materials and liposome aggregation [85,86].…”