A synthetic derivative of natural neolignans from Krameria lappacea (Dombey) Burdet: effect on planktonic and sessile form of staphylococci

  • Andrea Cellini, 'Sapienza' University, Rome, ITALY, Italy
  • Ezio Bombardelli, Indena SpA, Milan, Italy, Italy
  • Rosanna Papa, 'Sapienza' University, Rome, ITALY, Italy
  • Gian Luca Scoarughi, 'Sapienza' University, Rome, ITALY, Italy
  • Marco Artini, Sapienza University, Rome, ITALY, Italy
  • Paolo Morazzoni, Indena SpA, Milan, Italy, Italy
  • Laura Selan, Sapienza University, Rome, ITALY, Italy

    • Objective: Benzofurans of natural origin (alkaloids, pterocarpans, flavonoids etc.) have been found to possess a wide range of biological activities including antioxidant, antimicrobial and anti-inflammatory activities. We analyzed the antimicrobial effect of a synthetic derivative of the dihydroxybenzofuran (DHBF), originally isolated from Krameria lappacea (Dombey) Burdet. This plant is well known in medicine for its bronchodilator, antiviral, antioxidant and photoprotective properties due to the high production of lignans and neolignans. In the present study the effect of DHBF was analyzed for its antibacterial activity against S. aureus and S. epidermidis planktonic and sessile cultures.

    Methods: S. aureus 6538P and S. epidermidis RP62A strains were used. Determination of MIC and MBC for DHBF was carried out. Its influence on biofilm formation was assessed by using crystal violet. The effect of DHBF on surface proteins and autolysins was evaluated by SDS-PAGE and zymogram, respectively. Surface proteins were extracted from bacteria grown in the absence and in the presence of sub-inhibiting concentration of DHBF. In order to study the modulation of surface adhesins/autolysins, zymograms were also performed.

    Results: DHBF shows a strong bactericidal activity on the two tested bacterial strains in planktonic form. A marked inhibition of biofilm formation of two strains tested was also observed. The inhibition effect of preformed biofilm of S. aureus and S. epidermidis was significant at concentration twice than MIC/MBC values. In order to evaluate the influence of DHBF on surface protein patterns for both strains SDS-PAGE and zymogram analyses were carried out. SDS-PAGE analysis revealed a modification of surface protein pattern for treated bacteria in comparison with that of untreated bacteria. Analysis of zymogram pattern under the same conditions is ongoing.

    Conclusions: The data obtained show that DHBF treatment is effective to impair adhesion by Staphylococcus spp to abiotic surfaces. DHBF strongly reduces also the biomass of preformed biofilm, suggesting a possible application in biofilm infections.