<i>In vitro</i> anti-quorum sensing activity of phytol

<div><p>Anti-quorum sensing activity of the diterpene phytol was evaluated <i>in vitro</i> for the first time. This compound (at three sub-MIC concentrations – 0.5, 0.25 and 0.125 MIC, respectively) reduced the formation of <i>Pseudomonas aeruginosa</i> PAO1 biofilm in the range of 74.00–84.33% exhibiting higher activity than the both positive controls used, streptomycin and ampicillin. Phytol (0.5 MIC) also effectively reduced <i>P. aeruginosa</i> twitching and flagella motility. Indeed, the bacteria treated were incapable of producing a twitching zone and had almost round, smooth and regular colony edges. Finally, the tested compound (0.5 MIC) exhibited good <i>P. aeruginosa</i> pyocyanin inhibitory activity (51.94%) practically to the same extent as streptomycin (52.09%). According to the experimental data obtained, this phytol property may inspire design of medical foods targeting <i>P. aeruginosa</i> quorum sensing activity.</p></div

<i>In vitro</i> avarol does affect the growth of <i>Candida</i> sp.

<p>This work extends <i>in vitro</i> screening of antimicrobial activity of avarol, the marine natural product firstly isolated from the Mediterranean sponge <i>Dysidea avara</i>. Its anticandidial activity was evaluated by microdilution method against eight <i>Candida</i> strains, two ATCC and six clinical ones. At a different extent this compound was proven to be active against all the strains tested (MIC 0.8–6.0 μg/mL and MFC 1.6–12.0 μg/mL, respectively). According to the best of our knowledge, this is the first report on avarol activity towards any yeast strain which may be of relevance for Alzheimer’s disease. Indeed, avarol derivatives showing moderate AChE activity should be screened for anticandidial activity both <i>in vitro</i> and <i>in vivo</i>.</p

An insight into anti-biofilm and anti-quorum sensing activities of the selected anthocyanidins: the case study of <i>Pseudomonas aeruginosa</i> PAO1

<p>Anti-biofilm activity of three anthocyanidins (pelargonidin, cyanidin and delphinidin) was evaluated for the first time at <i>in vitro</i> conditions. All the compounds reduced the formation of <i>Pseudomonas aeruginosa</i> PAO1 biofilm at low sub-MIC (0.125 MIC) with delphinidin (c 56.25 μg/mL) being the most active (43%). In comparison, ampicillin (c 93.75 μg/mL) and streptomycin (c 21.25 μg/mL) (used as positive controls) were considerably less effective at the same sub-MIC (8 and 12%, respectively). Furthermore, at 0.5 MIC (c 225 μg/mL) this anthocyanidin molecule partly reduced the bacterial protrusions. However, no any of the aforementioned compounds inhibited the production of pyocyanin by the bacterial strain <i>P. aeruginosa</i> PAO1. Taken all together, the delphinidin scaffold could be taken into consideration for the design of the novel and more effective anti-biofilm agents inspired by the anthocyanidins.</p

<i>In vitro</i> antibiofilm activity of the freshwater bryozoan <i>Hyalinella punctata</i>: a case study of <i>Pseudomonas aeruginosa</i> PAO1

<p>The antibiofilm and possible antiquorum sensing effects against the strain <i>Pseudomonas aeruginosa</i> PAO1 of five crude extracts of the freshwater bryozoan <i>Hyalinella punctata</i> (Hancock, 1850) were evaluated <i>in vitro</i> for the first time. <i>H. punctata</i> ethyl acetate extract (HpEtAc) exhibited the highest antibiofilm activity reducing the biofilm formation of <i>P. aeruginosa</i> PAO1 in the range of 80.63–88.13%. While all tested extracts reduced the twitching motility of the aforementioned bacterial strain, HpEtAc showed to be the most effective. Finally, at a concentration of 0.5 MIC, the same extract mostly inhibited the production of pyocyanin by <i>P. aeruginosa</i> PAO1 (71.53%). In comparison both with the positive controls used (streptomycin and ampicillin, 67.13 and 69.77%, respectively), HpEtAc was found to inhibit pyocyanin in a higher extent. An extensive chemical characterisation of this particular extract may result in isolation and identification of novel lead compounds targeting <i>P. aeruginosa</i>, an opportunistic human pathogen.</p

Anti-quorum sensing activity of selected sponge extracts: a case study of <i>Pseudomonas aeruginosa</i>

<div><p>The anti-quorum sensing activities towards the bacterium <i>Pseudomonas aeruginosa</i> PA01 (pyocyanin production, biofilm formation and twitching and flagella motility) of two crude extracts (methanol and acetone) of the freshwater sponge <i>Ochridaspongia rotunda</i> (Arndt, 1937) were evaluated <i>in vitro</i> for the first time. Both extracts demonstrated <i>P. aeruginosa</i> pyocyanin inhibitory activity, reducing its production for 49.90% and 42.44%, respectively. In addition, they both showed higher anti-biofilm activity (48.29% and 53.99%, respectively) than ampicillin (30.84%). Finally, <i>O. rotunda</i> extracts effectively reduced twitching and flagella motility of <i>P. aeruginosa</i>. Taken all together, these results suggest that endemic sponge species from the oldest lake in Europe may offer novel bioactive natural products with promising medicinal potential towards <i>P. aeruginosa</i> infections.</p></div

An insight into antimicrobial activity of the freshwater bryozoan <i>Pectinatella magnifica</i>

<p>The antimicrobial activity of five crude extracts of the freshwater bryozoan <i>Pectinatella magnifica</i> (Leidy, 1851) was evaluated <i>in vitro</i> for the first time. <i>P. magnifica</i> acetone extract exhibited the highest antibacterial activity (minimum inhibitory concentrations (MIC) 0.004–0.350 mg/mL and MBC 0.007–0.500 mg/mL), while its methanol extract showed the most promising antifungal activity (MIC 0.03–0.12 mg/mL and MFC 0.06–0.25 mg/mL). Furthermore, at a concentration of 0.25 MIC, the methanol extract reduced biofilm formation of the bacterial strain <i>Pseudomonas aeruginosa</i> PAO1 in a considerable extent (59.14%). FTIR spectra of the most active extracts indicate the presence of carbonyl compounds, long-chain alcohols and/or sterols. According to the experimental data obtained, <i>P. magnifica</i> methanol extract may be considered as a good resource of novel natural products with potent antibiofilm activity against the bacterium well known for its resistance.</p