You are here: Home Published Research A chalcone with potent inhibiting activity against biofilm formation of nontypeable Haemophilus influenzae.

Duangkamol Kunthalert, Sudarat Baothong, Pichit Khetkam, Suwadee Chokchaisiri, and Apichart Suksamrarn (2014)

A chalcone with potent inhibiting activity against biofilm formation of nontypeable Haemophilus influenzae.

Microbiology and immunology.

Nontypeable Haemophilus influenzae (NTHi) is an important human respiratory pathogen and this bacterium frequently causes biofilm infections. Resistance to conventional antimicrobials of bacteria within the biofilm poses a major difficulty in current medical treatment on a global scale. Novel agents that are effective against NTHi biofilm are therefore required and in an urgent need. In this study, a series of natural and synthetic chalcones with various chemical substituents were evaluated in vitro for their antibiofilm activities against strong biofilm-forming strains of NTHi. Of the test chalcones, 3-hydroxychalcone (chalcone 8) exhibited the most potent inhibitory activity, with mean minimum biofilm inhibitory concentration (MBIC50 ) value of 16 μg/mL (71.35 μM), or approximately 6-fold more active than azithromycin (MBIC50 419.68 μM), the reference drug. The inhibitory activity of chalcone 8 which was a chemically modified chalcone, appeared to be superior to those of natural chalcones tested. Significantly, chalcone 8 effectively inhibited biofilm formation of all studied NTHi strains. This indicated that antibiofilm activities of such compound occurred across multiple strong-biofilm forming NTHi isolates of different clinical origins. As examined by antimicrobial and growth curve assays, chalcone 8 at concentration that decreased biofilm formation did not affect growth of NTHi, suggesting a non-antimicrobial biofilm inhibitory effect of chalcone 8. In terms of structure-activity relationship, the potential substituent on the chalcone backbone required for antibiofilm activity was discussed. These results indicated the powerful antibiofilm action of 3-hydroxychalcone (chalcone 8) and suggested the potential application of chalcone 8 as a new therapeutic agent for control of NTHi biofilm-associated infections.

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