title: Endemic malagasy Dalbergia species inhibit quorum sensing in Pseudomonas aeruginosa PAO1.
abstract: Various species of the plant genus Dalbergia are traditionally used as medicine for sundry ailments and some of them have been shown recently to quench the virulence of Gram-positive and Gram-negative bacteria. Cell-to-cell communication mechanisms, quorum sensing (QS) in particular, are key regulators of virulence in many pathogenic bacteria. Screening n-hexane extracts of leaves, roots and bark of endemic Malagasy Dalbergia species for their capacity to antagonize QS mechanisms in Pseudomonas aeruginosa PAO1 showed that many reduced the expression of the QS-regulated genes lasB and rhlA. However, only the extract of Dalbergia trichocarpa bark (DTB) showed a significant reduction of QS gene expression without any effect on the aceA gene encoding a QS-independent isocitrate lyase. Further characterization of DTB impact on QS revealed that the QS systems las and rhl are inhibited and that swarming, twitching, biofilm formation and the production of pyocyanin, elastase and proteases are also hampered in the presence of the DTB extract. Importantly, compared with the known QS inhibitor naringenin, the DTB extract showed a stronger negative effect on twitching, biofilm formation and tobramycin resistance. Preliminary structural characterization of these potent biofilm disrupters suggests that they belong to the phytosterols. The strong inhibition of motility and biofilm formation suggests that the DTB extract contains agents disrupting biofilm architecture, which is an important observation in the context of the design of new drugs targeting biofilm-encapsulated pathogens.
authors: Laboratoire de Formation et de Recherche en Biologie Médicale, Université d'Antananarivo, B.P. 566 Antananarivo 101, Madagascar.|Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Tsiry
authors: T
authors: Rasamiravaka
authors: Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Anaïs
authors: A
authors: Jedrzejowski
authors: Laboratoire de Biochimie et de Chimie Appliquées, Université de Ouagadougou, 09 BP 848 Ouagadougou 09, Burkina Faso.|Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Martin
authors: M
authors: Kiendrebeogo
authors: Laboratoire de Physiologie Végétale, Université d'Antananarivo, B.P. 906 Antananarivo 101, Madagascar.|Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Sanda
authors: S
authors: Rajaonson
authors: Laboratoire de Physiologie Végétale, Université d'Antananarivo, B.P. 906 Antananarivo 101, Madagascar.|Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Denis
authors: D
authors: Randriamampionona
authors: Laboratoire de Biodiversité et de Biotechnologie, Institut Malgache de Recherches Appliquées (IMRA), B.P. 3833 Avarabohitra Itaosy, Antananarivo 102, Madagascar.
authors: Christian
authors: C
authors: Rabemanantsoa
authors: Laboratoire de Formation et de Recherche en Biologie Médicale, Université d'Antananarivo, B.P. 566 Antananarivo 101, Madagascar.
authors: Abel
authors: A
authors: Andriantsimahavandy
authors: Laboratoire de Formation et de Recherche en Biologie Médicale, Université d'Antananarivo, B.P. 566 Antananarivo 101, Madagascar.
authors: Andry
authors: A
authors: Rasamindrakotroka
authors: Laboratoire de Pharmacognosie, de Bromatologie et de Nutrition Humaine, Université Libre de Bruxelles, CP 205/9, Boulevard du Triomphe, B-1050 Brussels, Belgium.
authors: Pierre
authors: P
authors: Duez
authors: Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Mondher
authors: M
authors: El Jaziri
authors: Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, 12 rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors: Olivier M
authors: OM
authors: Vandeputte
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects; D035782:Dalbergia / Q000737:chemistry* / Q000145:classification; D015536:Down-Regulation / Q000187:drug effects; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D010840:Phytosterols / Q000737:chemistry / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology*; D053038:Quorum Sensing / Q000187:drug effects*
chemical_list: D001426:Bacterial Proteins; D010840:Phytosterols; D010936:Plant Extracts