Antimicrobial activity of nitrochalcone and pentyl caffeate against hospital pathogens results in decreased microbial adhesion and biofilm formation.

The present study investigated the antimicrobial, anti-adhesion and anti-biofilm activity of the modified synthetic molecules nitrochalcone (NC-E05) and pentyl caffeate (C5) against microorganisms which have a high incidence in hospital-acquired infections. The compounds were further tested for their preliminary systemic toxicity in vivo. NC-E05 and C5 showed antimicrobial activity, with minimum inhibitory concentrations (MICs) ranging between 15.62 and 31.25 μg ml-1. Treatment with NC-E05 and C5 at 1 × MIC and/or 10 × MIC significantly reduced mono or mixed-species biofilm formation and viability. At MIC/2, the compounds decreased microbial adhesion to HaCaT keratinocytes from 1 to 3 h (p < 0.0001). In addition, NC-E05 and C5 demonstrated low toxicity in vivo in the Galleria mellonella model at anti-biofilm concentrations. Thus, the chemical modification of these molecules proved to be effective in the proposed anti-biofilm activity, opening opportunities for the development of new antimicrobials.