HEALTH NEWS

Study Title:

Quercetin and Other Citrus Flavonoids Disrupt E. Coli Biofilms

Study Abstract

AIM:
This study investigated the quorum sensing, biofilm and type three secretion system (TTSS) inhibitory properties of citrus flavonoids.

METHODS AND RESULTS:
Flavonoids were tested for their ability to inhibit quorum sensing using Vibrio harveyi reporter assay. Biofilm assays were carried out in 96-well plates. Inhibition of biofilm formation in Escherichia coli O157:H7 and V. harveyi by citrus flavonoids was measured. Furthermore, effect of naringenin on expression of V. harveyi TTSS was investigated by semi-quantitative PCR. Differential responses for different flavonoids were observed for different cell-cell signalling systems. Among the tested flavonoids, naringenin, kaempferol, quercetin and apigenin were effective antagonists of cell-cell signalling. Furthermore, these flavonoids suppressed the biofilm formation in V. harveyi and E. coli O157:H7. In addition, naringenin altered the expression of genes encoding TTSS in V. harveyi.

CONCLUSION:
The results of the study indicate a potential modulation of bacterial cell-cell communication, E. coli O157:H7 biofilm and V. harveyi virulence, by flavonoids especially naringenin, quercetin, sinensetin and apigenin. Among the tested flavonoids, naringenin emerged as potent and possibly a nonspecific inhibitor of autoinducer-mediated cell-cell signalling. Naringenin and other flavonoids are prominent secondary metabolites present in citrus species. Therefore, citrus, being a major source of some of these flavonoids and by virtue of widely consumed fruit, may modulate the intestinal microflora.

SIGNIFICANCE AND IMPACT OF THE STUDY:
Currently, a limited number of naturally occurring compounds have demonstrated their potential in inhibition of cell-cell communications; therefore, citrus flavonoids may be useful as lead compounds for the development of antipathogenic agents.

Study Information

Vikram A, Jayaprakasha GK, Jesudhasan PR, Pillai SD, Patil BS.
Suppression of bacterial cell-cell signalling, biofilm formation and type III secretion system by citrus flavonoids.
Appl Microbiol.
2010 August
Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A&M University, College Station, TX 77843-2119, USA.