title: Synergistic antimicrobial activity of galangal (Alpinia galanga), rosemary (Rosmarinus officinalis) and lemon iron bark (Eucalyptus staigerana) extracts.
abstract: BACKGROUND
  In this study the synergistic antimicrobial activities of combinations of extracts from galangal (Alpinia galanga), rosemary (Rosmarinus officinalis) and lemon iron bark (Eucalyptus staigerana) were evaluated against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Clostridium perfringens. Chemical compositions of these extracts were also determined to provide further insight into antimicrobial constituents and their potential mechanisms of action.
  
  
  RESULTS
  Combinations of galangal with either rosemary or lemon iron bark showed synergistic antimicrobial activity. Specifically, galangal and rosemary showed synergistic activity against S. aureus and L. monocytogenes only, while galangal and lemon iron bark showed synergistic activity against E. coli and S. typhimurium. Chemical compositions of the extracts were determined by gas chromatographic-mass spectrometric analysis. The major chemical components of the galangal and lemon iron bark extracts were 1'-acetoxy-chavicol acetate (1'ACA) (63.4%) and neral (15.6%), respectively, while 1,8-cineole (26.3%) and camphor (20.3%) were identified as major chemical components of the rosemary extract.
  
  
  CONCLUSIONS
  The results of this study show that galangal, rosemary and lemon iron bark extracts contain components that may have different modes of antimicrobial action and combinations of these extracts may have potential as natural antimicrobials to preserve foods.
authors.affiliation: School of Land, Crop and Food Sciences, University of Queensland, St Lucia, QLD 4072, Australia.
authors.forename: Nimsha S
authors.initials: NS
authors.lastname: Weerakkody
authors.forename: Nola
authors.initials: N
authors.lastname: Caffin
authors.forename: Lynette K
authors.initials: LK
authors.lastname: Lambert
authors.forename: Mark S
authors.initials: MS
authors.lastname: Turner
authors.forename: Gary A
authors.initials: GA
authors.lastname: Dykes
mesh_terms: D032429:Alpinia / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000032:analysis / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D004357:Drug Synergism; D005052:Eucalyptus / Q000737:chemistry*; D005658:Fungi / Q000187:drug effects*; D008401:Gas Chromatography-Mass Spectrometry; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D027542:Rosmarinus / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D010936:Plant Extracts