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.

Hepatitis C virus in vitro replication is efficiently inhibited by acridone Fac4.

Hepatitis C virus (HCV) affects about 170 million people worldwide. The current treatment has a high cost and variable response rates according to the virus genotype. Acridones, a group of compounds extracted from natural sources, showed potential antiviral actions against HCV. Thus, this study aimed to evaluate the effect of a panel of 14 synthetic acridones on the HCV life cycle. The compounds were screened using an Huh7.5 cell line stably harbouring the HCV genotype 2a subgenomic replicon SGR-Feo-JFH-1. Cells were incubated in the presence or absence of compounds for 72 h and cell viability and replication levels were assessed by MTT and luciferase assays, respectively. At a concentration of 5 µM the acridone Fac4 exhibited a >90 % inhibition of HCV replication with no effect on cell viability. The effects of Fac4 on virus replication, entry and release steps were evaluated in Huh7.5 cells infected with the JFH-1 isolate of HCV (HCVcc). Fac4 inhibited JFH-1 replication to approximately 70 %, while no effect was observed on virus entry. The antiviral activity of Fac4 was also observed on viral release, with almost 80 % of inhibition. No inhibitory effect was observed against genotype 3 replication. Fac4 was able to intercalate into dsRNA, however did not inhibit NS5B polymerase activity or translation driven by the HCV IRES. Although its mode of action is partly understood, Fac4 presents significant inhibition of HCV replication and can therefore be considered as a candidate for the development of a future anti-HCV treatment.