Anti-quorum sensing potential of crude Kigelia africana fruit extracts

• Published in: Sensors (Basel, Switzerland) Switzerland), 2013-02, Vol.13 (3), p.2802-2817
• Main Author: Chenia, Hafizah Y
• Format: Article
• Language: English
• Subjects: Agrobacterium tumefaciens - drug effects; Agrobacterium tumefaciens - growth & development; Antimicrobial agents; Bacteria; Bacterial infections; Bignoniaceae - chemistry; Biosensing Techniques; Breastfeeding & lactation; Chromobacterium - drug effects; Chromobacterium - growth & development; Drug resistance; Drug Resistance, Microbial - genetics; Fruit - chemistry; Fruits; Herbal medicine; Humans; Infections; Kigelia africana; Metabolites; Pathogenesis; Pathogens; phytochemical extracts; Phytochemicals; Plant Extracts - chemistry; Plant Extracts - pharmacology; Quorum Sensing - drug effects; quorum sensing inhibition; Sensors; Tropical diseases; Virulence
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s130302802

The increasing incidence of multidrug-resistant pathogens has stimulated the search for novel anti-virulence compounds. Although many phytochemicals show promising antimicrobial activity, their power lies in their anti-virulence properties. Thus the quorum sensing (QS) inhibitory activity of four crude Kigelia africana fruit extracts was assessed qualitatively and quantitatively using the Chromobacterium violaceum and Agrobacterium tumefaciens biosensor systems. Inhibition of QS-controlled violacein production in C. violaceum was assayed using the qualitative agar diffusion assay as well as by quantifying violacein inhibition using K. africana extracts ranging from 0.31-8.2 mg/mL. Qualitative modulation of QS activity was investigated using the agar diffusion double ring assay. All four extracts showed varying levels of anti-QS activity with zones of violacein inhibition ranging from 9-10 mm. The effect on violacein inhibition was significant in the following order: hexane > dichloromethane > ethyl acetate > methanol. Inhibition was concentration-dependent, with the ≥90% inhibition being obtained with ≥1.3 mg/mL of the hexane extract. Both LuxI and LuxR activity were affected by crude extracts suggesting that the phytochemicals target both QS signal and receptor. K. africana extracts with their anti-QS activity, have the potential to be novel therapeutic agents, which might be important in reducing virulence and pathogenicity of drug-resistant bacteria in vivo.