title: Subinhibitory concentrations of perilla oil affect the expression of secreted virulence factor genes in Staphylococcus aureus.
abstract: BACKGROUND
  The pathogenicity of staphylococcus aureus is dependent largely upon its ability to secrete a number of virulence factors, therefore, anti-virulence strategy to combat S. aureus-mediated infections is now gaining great interest. It is widely recognized that some plant essential oils could affect the production of staphylococcal exotoxins when used at subinhibitory concentrations. Perilla [Perilla frutescens (L.) Britton], a natural medicine found in eastern Asia, is primarily used as both a medicinal and culinary herb. Its essential oil (perilla oil) has been previously demonstrated to be active against S. aureus. However, there are no data on the influence of perilla oil on the production of S. aureus exotoxins.
  
  
  RESULTS
  A broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of perilla oil against S. aureus strains. Hemolysis, tumour necrosis factor (TNF) release, Western blot, and real-time RT-PCR assays were performed to evaluate the effects of subinhibitory concentrations of perilla oil on exotoxins production in S. aureus. The data presented here show that perilla oil dose-dependently decreased the production of α-toxin, enterotoxins A and B (the major staphylococcal enterotoxins), and toxic shock syndrome toxin 1 (TSST-1) in both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA).
  
  
  CONCLUSIONS
  The production of α-toxin, SEA, SEB, and TSST-1 in S. aureus was decreased by perilla oil. These data suggest that perilla oil may be useful for the treatment of S. aureus infections when used in combination with β-lactam antibiotics, which can increase exotoxins production by S. aureus at subinhibitory concentrations. Furthermore, perilla oil could be rationally applied in food systems as a novel food preservative both to inhibit the growth of S. aureus and to repress the production of exotoxins, particularly staphylococcal enterotoxins.
authors.affiliation: Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Animal Science and Veterinary Medicine, Jilin University, Changchun, People's Republic of China.
authors.forename: Jiazhang
authors.initials: J
authors.lastname: Qiu
authors.forename: Xiaoran
authors.initials: X
authors.lastname: Zhang
authors.forename: Mingjing
authors.initials: M
authors.lastname: Luo
authors.forename: Hongen
authors.initials: H
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Dong
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Wang
authors.forename: Bingfeng
authors.initials: B
authors.lastname: Leng
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Wang
authors.forename: Haihua
authors.initials: H
authors.lastname: Feng
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Ren
authors.forename: Xuming
authors.initials: X
authors.lastname: Deng
mesh_terms: D000900:Anti-Bacterial Agents; D016588:Anticarcinogenic Agents; D005098:Exotoxins / Q000096:biosynthesis / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D010938:Plant Oils / Q000494:pharmacology; D010946:Plants, Medicinal; D013211:Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics*; D017962:alpha-Linolenic Acid / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D016588:Anticarcinogenic Agents; D005098:Exotoxins; D010938:Plant Oils; D037521:Virulence Factors; D017962:alpha-Linolenic Acid; C058216:perilla seed oil