Quercus cerris extracts limit Staphylococcus aureus biofilm formation

• Type of Material: Article
• Authors: Gerren H. Hobby, University of Arkansas for Medical Sciences; Cassandra Leah Quave, Emory University; Katie Nelson, Emory University; Cesar M. Compadre, University of Arkansas for Medical Sciences; Karen E. Beenken, University of Arkansas for Medical Sciences; Mark S. Smeltzer, University of Arkansas for Medical Sciences
• Language: English
• Date: 2012-12-18
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2012 Elsevier Ireland Ltd. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.jep.2012.10.042
• Title of Journal or Parent Work: Journal of Ethnopharmacology
• ISSN: 0378-8741
• Volume: 144
• Issue: 3
• Start Page: 812
• End Page: 815
• Grant/Funding Information: The funding agencies had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.; This project was supported by an F32 Fellowship to CLQ (AT005040) from the NIH National Center for Complementary and Alternative Medicine (NCCAM) and by the US Department of Defense grant USAMRAA OR090571 to MSS.
• Keywords: Oak; Quercus cerris; Staphylococcus aureus; biofilm
• Research Categories: Health Sciences, Immunology; Health Sciences, Pharmacology; Health Sciences, Pathology

Abstract

Ethnopharmacological relevance Quercus cerris L., Fagaceae has been used in traditional Mediterranean medicine for numerous purposes, including anti-infective therapies for diarrhea and wound care. Aim of the study To evaluate the anti-staphylococcal activity of fractions of ethanolic extracts of Q. cerris leaf and stem/fruit samples in models for biofilm and growth inhibition. Materials and methods Ethanolic extracts of Q. cerris leaves and stems/fruits were prepared, resuspended in water and fractioned by successively partitioning with hexane, ethyl acetate and butanol. The ability of the fractions to inhibit Staphylococcus aureus biofilm formation was tested using static crystal violet staining methods and confocal laser scanning microscopy. Growth studies were conducted to determine if the diminished capacity to form a biofilm was related to growth inhibition. Results The butanol extracts of both the leaf and stem/fruit samples were the most active, and at a dose of 200 μg/ml, the capacity to form a biofilm was limited to a level equivalent to that of the sarA mutant controls. Further examination of the impact of these fractions on S. aureus growth revealed that biofilm inhibition by the leaf butanol fraction was due to its bacteriostatic activity. The stem/fruit butanol fraction, however, showed a limited impact on growth, thus demonstrating that biofilm inhibition in this case is not related to the bacteriostatic activity of the extract. Conclusion Our evaluation of a medicinal plant used in Mediterranean ethnotherapies for infectious disease has demonstrated significant activity in the inhibition of staphylococcal biofilm formation with a mechanism unrelated to staphylococcal growth inhibition. These results contribute towards validation of this botanical remedy and form the groundwork for future studies in the search for novel biofilm inhibiting drugs.