To establish the effect of Quercus infectoria G. Olivier extract and its main constituent, tannic acid, on staphylococcal biofilm and their anti-biofilm mechanisms.
Anti-biofilm activity of the plant materials on clinical isolated of methicillin-resistant Staphylococcus aureus and methicillin-susceptible Staph. aureus was employed using a crystal violet-stained microtiter plate method. The extract at minimum inhibitory concentration (MIC; 0.25 mg ml(-1)) was significantly reduced the biofilm formation of the isolates (P < 0.05). The effect on staphylococcal cell surface hydrophobicity (CSH) of the test compounds was investigated as a possible mode of action of the anti-biofilm activity. The hydrophobicity index of all the bacterial isolates increased following treatment with supra-MIC, MIC and sub-MIC of the extract and tannic acid. Observation of the treated bacterial cells by electron microscopy revealed that the test compounds caused clumps of partly divided cocci with thickened and slightly rough cell wall.
The results indicated that Q. infectoria extract and tannic acid affected staphylococcal biofilm formation and their effect on bacterial CSH and cell wall may involve in the anti-biofilm activity.
This evidence highlighted the anti-biofilm potency of the natural products and clarified their anti-biofilm mechanisms.
[Show abstract][Hide abstract] ABSTRACT: Staphylococcus aureus is a human commensal and pathogen that is capable of forming biofilms on a variety of host tissues and implanted medical
devices. Biofilm-associated infections resist antimicrobial chemotherapy and attack from the host immune system, making these
infections particularly difficult to treat. In order to gain insight into environmental conditions that influence S. aureus biofilm development, we screened a library of small molecules for the ability to inhibit S. aureus biofilm formation. This led to the finding that the polyphenolic compound tannic acid inhibits S. aureus biofilm formation in multiple biofilm models without inhibiting bacterial growth. We present evidence that tannic acid inhibits
S. aureus biofilm formation via a mechanism dependent upon the putative transglycosylase IsaA. Tannic acid did not inhibit biofilm
formation of an isaA mutant. Overexpression of wild-type IsaA inhibited biofilm formation, whereas overexpression of a catalytically dead IsaA
had no effect. Tannin-containing drinks like tea have been found to reduce methicillin-resistant S. aureus nasal colonization. We found that black tea inhibited S. aureus biofilm development and that an isaA mutant resisted this inhibition. Antibiofilm activity was eliminated from tea when milk was added to precipitate the tannic
acid. Finally, we developed a rodent model for S. aureus throat colonization and found that tea consumption reduced S. aureus throat colonization via an isaA-dependent mechanism. These findings provide insight into a molecular mechanism by which commonly consumed polyphenolic compounds,
such as tannins, influence S. aureus surface colonization.
Infection and immunity 12/2012; 81:(2). DOI:10.1128/IAI.00877-12 · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Tannins are a diverse group of plant-produced, polyphenolic compounds with metal-chelating and antimicrobial properties that
are prevalent in many soils. Using transcriptomics, we determined that tannic acid, a form of hydrolysable tannin, broadly
affects the expression of genes involved in iron and zinc homeostases, sulfur metabolism, biofilm formation, motility, and
secondary metabolite biosynthesis in the soil- and rhizosphere-inhabiting bacterium Pseudomonas protegens Pf-5.
[Show abstract][Hide abstract] ABSTRACT: Nowadays, The Patient Safety Is Seriously Jeopardized By The Emergence And Spread Of Nosocomial Pathogens In The Form Of Biofilm That Is Resistant To Traditional And Affordable Antimicrobials. Although Advances In Organic Synthesis Have Extended The Lifetime Of Classic Antibiotics Through Synthetic Modifications, The Search Of Innovative Antibiofilm Compounds From Natural Sources Can Provide New Templates, Novel Targets And Unique Mechanisms That Should Have Advantages Over Known Antimicrobial Agents. Testing Sub-Lethal Concentrations Of Crude Extracts And/Or Isolated Compounds From Plants And Microorganisms Is Critical To Acting On Mechanisms Subtler Than The Killing Activity, E.G. Those Influencing The Multicellular Behavior, Offering An Elegant Way To Develop Novel Antimicrobial-Free Antibiofilm Strategies. Herein We Discussed The Search And Biological Activity Of Small Molecules From Natural Sources And Their Synthetic Derivatives Able To Modulate Biofilm Genesis Of Nosocomial Pathogens Through Non-Microbicidal Mechanisms (Sub-Lethal Concentrations). The Present Work Offers An Overview About The Approaches Applied To The Discovery Of Lead Small Molecules Including A) Conventional Drug Design Methods Like Screening Of Chemical Compounds Obtained From Nature And B) Computer-Aided Drug Design Approaches. Finally, A Classification (Not Exhaustive But Representative) Based On The Natural Origin Of Small Molecules And Their Synthetic Derivatives Was Reported. The Information Presented In This Review Should Be Of Interest To A Broad Range Of Disciplines And Represents An Effort To Summarize Experimental Research And Advances In This Field.
Current topics in medicinal chemistry 11/2013; 13(24). DOI:10.2174/15680266113136660225 · 3.40 Impact Factor
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