Background Rosmarinus officinalis L. from Tunisia, popularly known as rosemary, is of a considerable importance for its medicinal uses and aromatic value. The aim of this study was to examine the chemical composition of Rosmarinus officinalis essential oil (ROEO) and to evaluate its antibiofilm activity on biofilm-forming bacterium and its anticancer activity on cancer cell lines.MethodsThe chemical composition of Rosmarinus officinalis essential oil (ROEO) was analyzed by GC-MS and its antibacterial activity was evaluated by micro-dilution method. The antibofilm activity of ROEO was evaluated using the crystal violet test and the cytotoxicity activity was determined by the MTT assay.ResultsIn this research, thirty-six compounds were identified in ROEO using GC-MS analyses. The main components were 1,8-cineole (23.56%), camphene (12.78%), camphor (12.55%) and β-pinene (12.3%). The antibacterial activity of ROEO was evaluated by micro-dilution method. The oil exhibited inhibition and bactericidal effect against two strains: Staphylococcus aureus ATCC 9144 and Staphylococcus epidermidis S61. It was found that the minimum inhibitory concentration (MIC) obtained for S. aureus and S. epidermidis ranged from 1.25 to 2.5 and from 0.312 to 0.625 μl ml−1, respectively and the minimum bactericidal concentration (MBC) were in the order of 5 and 2.5 μl ml−1, respectively. Furthermore, this oil showed a S. epidermidis biofilm inhibition more than 57% at a concentration of 25 μl ml−1. The eradication of 67% of the established biofilm was observed at a concentration of 50 μl ml−1 of ROEO, whereas the dose of 25 μl ml−1 removed only 38% of preformed biofilm. ROEO strongly inhibited the proliferation of Hela and MCF-7 cells with IC50 values of 0.011 and 0.253 μl ml−1, respectively.ConclusionOur results demonstrate that ROEO could have a potential role in the treatment of diseases related to infection by microorganisms or proliferation of cancer cells.

The bacterial strain F4, isolated from olive oil-contaminated soil, has been found to produce biosurfactants as confirmed by oil displacement test and the emulsification index results. The identification of the strain F4, by 16S ribosomal RNA gene, showed a close similarity to Bacillus safensis, therefore the strain has been termed Bacillus safensis F4. The Thin Layer Chromatography (TLC) and the High Pressure LiquidChromatography-Mass Spectrometry (HPLC-MS/MS) demonstrated that the biosurfactant had a lipopeptide structure and was classified as surfactin. The present study showed also that the produced biosurfactant has an important antibacterial activity against several pathogen strains as monitored with minimum inhibitory concentration (MIC) micro-assays. In particular, it presented an interesting antiplanktonic activity with a MIC of 6.25 mg mL-1 and anti-adhesive activity which exceeded 80%against the biofilm-forming Staphylococcus epidermidis S61 strain. Moreover, the produced lipopeptide showed an antitumor activity against T47D breast cancer cells and B16F10 mouse melanoma cells with IC 50 of 0.66 mg mL-1 and 1.17 mg mL-1 , respectively. Thus, our results demonstrated that Bacillus safensis F4 biosurfactant exhibited a polyvalent activity via a considerableantibiofilm and antitumoralpotencies.

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