title: Tannin-rich fraction from Terminalia catappa inhibits quorum sensing (QS) in Chromobacterium violaceum and the QS-controlled biofilm maturation and LasA staphylolytic activity in Pseudomonas aeruginosa.
abstract: OBJECTIVE
  The study aimed to test the activity of Terminalia catappa L. against bacterial quorum sensing (QS) in order to provide a potential scientific basis for the traditional use of leaf extracts of this plant as an antiseptic.
  
  
  METHODS
  The anti-QS activity of the methanolic leaf extract of Terminalia catappa was detected through the inhibition of the QS-controlled violacein pigment production in Chromobacterium violaceum. Fractions resulting from size-exclusion chromatography were assayed. The most active fraction was characterized through qualitative phytochemical detection methods. The effect of this fraction on known QS-controlled phenotypes in test strains was assessed.
  
  
  RESULTS
  The fraction with the highest activity (labeled as TCF12) was characterized to be tannin-rich. It specifically inhibited QS-controlled violacein production in Chromobacterium violaceum with 50% reduction achieved at 62.5 μg mL(-1) without significantly affecting growth up to about 962 μg mL(-1). The assessment of its effects on LasA activity of Pseudomonas aeruginosa ATCC 10145 found that the production of this virulence determinant is reduced in a concentration dependent manner with about 50% reduction at 62.5 μg mL(-1). Furthermore, it was found that TCF12 was able to inhibit the maturation of biofilms of Pseudomonas aeruginosa, a phenotype that has also been known to be QS-regulated.
  
  
  CONCLUSIONS
  Therefore, tannin-rich components of Terminalia catappa leaves are able to inhibit certain phenotypic expression of QS in the test strains used.
authors.affiliation: Laboratory of Applied Microbiology, Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City 1101, Philippines. Joemar.Taganna@up.edu.ph
authors.forename: Joemar C
authors.initials: JC
authors.lastname: Taganna
authors.forename: Jusal P
authors.initials: JP
authors.lastname: Quanico
authors.forename: Rose Marie G
authors.initials: RM
authors.lastname: Perono
authors.forename: Evangeline C
authors.initials: EC
authors.lastname: Amor
authors.forename: Windell L
authors.initials: WL
authors.lastname: Rivera
mesh_terms: D018441:Biofilms; D002850:Chromatography, Gel; D002861:Chromobacterium / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D045726:Metalloproteases / Q000502:physiology*; D010936:Plant Extracts / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D053038:Quorum Sensing / Q000187:drug effects*; D013634:Tannins / Q000494:pharmacology*; D029766:Terminalia / Q000737:chemistry*; D037521:Virulence Factors / Q000502:physiology*
chemical_list: D010936:Plant Extracts; D013634:Tannins; D037521:Virulence Factors; C548166:LasA protein, Pseudomonas aeruginosa; D045726:Metalloproteases