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Ellagic acid derivatives from Terminalia chebula Retz. downregulate the expression of quorum sensing genes to attenuate Pseudomonas aeruginosa PAO1 virulence.

Sarabhai S, Sharma P, Capalash N - PLoS ONE (2013)

Bottom Line: Biofilm formation and alginate were significantly (p<0.05) reduced with enhanced (20%) susceptibility to tobramycin.Electrospray Ionization Mass Spectrometry also showed 90 and 64% reduction in the production of 3-oxo-C(12)HSL and C(4)HSL after treatment.This is the first report on anti QS activity of T. chebula fruit linked to EADs which down regulate the expression of lasIR and rhlIR genes with concomitant decrease in AHLs in P. aeruginosa PAO1 causing attenuation of its virulence factors and enhanced sensitivity of its biofilm towards tobramycin.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Panjab University, Chandigarh, India.

ABSTRACT

Background: Burgeoning antibiotic resistance in Pseudomonas aeruginosa has necessitated the development of anti pathogenic agents that can quench acylhomoserine lactone (AHL) mediated QS with least risk of resistance. This study explores the anti quorum sensing potential of T. chebula Retz. and identification of probable compounds(s) showing anti QS activity and the mechanism of attenuation of P. aeruginosa PAO1 virulence factors.

Methods and results: Methanol extract of T. chebula Retz. fruit showed anti QS activity using Agrobacterium tumefaciens A136. Bioactive fraction (F7), obtained by fractionation of methanol extract using Sephadex LH20, showed significant reduction (p<0.001) in QS regulated production of extracellular virulence factors in P. aeruginosa PAO1. Biofilm formation and alginate were significantly (p<0.05) reduced with enhanced (20%) susceptibility to tobramycin. Real Time PCR of F7 treated P. aeruginosa showed down regulation of autoinducer synthase (lasI and rhlI) and their cognate receptor (lasR and rhlR) genes by 89, 90, 90 and 93%, respectively. Electrospray Ionization Mass Spectrometry also showed 90 and 64% reduction in the production of 3-oxo-C(12)HSL and C(4)HSL after treatment. Decrease in AHLs as one of the mechanisms of quorum quenching by F7 was supported by the reversal of inhibited swarming motility in F7-treated P. aeruginosa PAO1 on addition of C(4)HSL. F7 also showed antagonistic activity against 3-oxo-C(12)HSL-dependent QS in E. coli bioreporter. C. elegans fed on F7-treated P. aeruginosa showed enhanced survival with LT50 increasing from 24 to 72 h. LC-ESI-MS of F7 revealed the presence of ellagic acid derivatives responsible for anti QS activity in T. chebula extract.

Conclusions: This is the first report on anti QS activity of T. chebula fruit linked to EADs which down regulate the expression of lasIR and rhlIR genes with concomitant decrease in AHLs in P. aeruginosa PAO1 causing attenuation of its virulence factors and enhanced sensitivity of its biofilm towards tobramycin.

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Schematic representation of bioassay guided fractionation of T. chebula fruit extract.
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pone-0053441-g001: Schematic representation of bioassay guided fractionation of T. chebula fruit extract.

Mentions: In order to separate the anti QS component(s), methanol extract fractionation scheme was followed as illustrated in Fig. 1. Fractions F6 and F7 showed anti QS activity indicated by 66 and 83% (p<0.001) reduction in violacein pigment production by biosensor CVO26, respectively (Fig. S2). However, anti QS components were probably more concentrated in F7 as it showed anti QS activity even at 0.1 mg/ml (data not shown). Phytochemical analysis of different fractions revealed the presence of terpenoides in F1 and F2, flavonoids in F6 and hydrolysable tannins in all seven fractions. However, protein precipitation assay confirmed the presence of higher amount of hydrolysable tannins in F4–F7 (Data not shown).


Ellagic acid derivatives from Terminalia chebula Retz. downregulate the expression of quorum sensing genes to attenuate Pseudomonas aeruginosa PAO1 virulence.

Sarabhai S, Sharma P, Capalash N - PLoS ONE (2013)

Schematic representation of bioassay guided fractionation of T. chebula fruit extract.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539995&req=5

pone-0053441-g001: Schematic representation of bioassay guided fractionation of T. chebula fruit extract.
Mentions: In order to separate the anti QS component(s), methanol extract fractionation scheme was followed as illustrated in Fig. 1. Fractions F6 and F7 showed anti QS activity indicated by 66 and 83% (p<0.001) reduction in violacein pigment production by biosensor CVO26, respectively (Fig. S2). However, anti QS components were probably more concentrated in F7 as it showed anti QS activity even at 0.1 mg/ml (data not shown). Phytochemical analysis of different fractions revealed the presence of terpenoides in F1 and F2, flavonoids in F6 and hydrolysable tannins in all seven fractions. However, protein precipitation assay confirmed the presence of higher amount of hydrolysable tannins in F4–F7 (Data not shown).

Bottom Line: Biofilm formation and alginate were significantly (p<0.05) reduced with enhanced (20%) susceptibility to tobramycin.Electrospray Ionization Mass Spectrometry also showed 90 and 64% reduction in the production of 3-oxo-C(12)HSL and C(4)HSL after treatment.This is the first report on anti QS activity of T. chebula fruit linked to EADs which down regulate the expression of lasIR and rhlIR genes with concomitant decrease in AHLs in P. aeruginosa PAO1 causing attenuation of its virulence factors and enhanced sensitivity of its biofilm towards tobramycin.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Panjab University, Chandigarh, India.

ABSTRACT

Background: Burgeoning antibiotic resistance in Pseudomonas aeruginosa has necessitated the development of anti pathogenic agents that can quench acylhomoserine lactone (AHL) mediated QS with least risk of resistance. This study explores the anti quorum sensing potential of T. chebula Retz. and identification of probable compounds(s) showing anti QS activity and the mechanism of attenuation of P. aeruginosa PAO1 virulence factors.

Methods and results: Methanol extract of T. chebula Retz. fruit showed anti QS activity using Agrobacterium tumefaciens A136. Bioactive fraction (F7), obtained by fractionation of methanol extract using Sephadex LH20, showed significant reduction (p<0.001) in QS regulated production of extracellular virulence factors in P. aeruginosa PAO1. Biofilm formation and alginate were significantly (p<0.05) reduced with enhanced (20%) susceptibility to tobramycin. Real Time PCR of F7 treated P. aeruginosa showed down regulation of autoinducer synthase (lasI and rhlI) and their cognate receptor (lasR and rhlR) genes by 89, 90, 90 and 93%, respectively. Electrospray Ionization Mass Spectrometry also showed 90 and 64% reduction in the production of 3-oxo-C(12)HSL and C(4)HSL after treatment. Decrease in AHLs as one of the mechanisms of quorum quenching by F7 was supported by the reversal of inhibited swarming motility in F7-treated P. aeruginosa PAO1 on addition of C(4)HSL. F7 also showed antagonistic activity against 3-oxo-C(12)HSL-dependent QS in E. coli bioreporter. C. elegans fed on F7-treated P. aeruginosa showed enhanced survival with LT50 increasing from 24 to 72 h. LC-ESI-MS of F7 revealed the presence of ellagic acid derivatives responsible for anti QS activity in T. chebula extract.

Conclusions: This is the first report on anti QS activity of T. chebula fruit linked to EADs which down regulate the expression of lasIR and rhlIR genes with concomitant decrease in AHLs in P. aeruginosa PAO1 causing attenuation of its virulence factors and enhanced sensitivity of its biofilm towards tobramycin.

Show MeSH
Related in: MedlinePlus