The antioxidant and antibacterial activities, and total phenolic contents of Rosa damascena Mill. flower extracts (absolute, essential oil and hydrosol) were investigated. The chemical compositions of these extracts were analysed by GC-MS. Phenylethyl alcohol (78.38%) was found to be the main constituent of rose absolute, while citrenellol and geraniol were the major compounds (>55%) of rose essential oil and hydrosol. Tocopherol and carotene levels were determined by high performance liquid chromatography (HPLC) analysis. The levels of beta carotene (422.3+/-35.6 ppm), alpha tocopherol (2397.1+/-72.5 ppm) and gamma tocopherol (343.1+/-28.4 ppm) of rose absolute were found to be higher than that of essential oil and hydrosol. Their total phenolic contents were also evaluated. The total phenolic content of the tested extracts varied from 5.2 to 2134.3 GAE/mg L(-1). Rose absolute and essential oil contained high levels of phenolics and demonstrated strong antibacterial activity against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538), Chromobacterium violaceum (ATCC 12472) and Erwinia carotovora (ATCC 39048) strains.

Introduction: In the opportunistic pathogen Pseudomonas aeruginosa, the production of several virulence factors depends on quorum sensing (QS) involving N-acylhomoserine lactone signal molecules. In vitro studies have suggested that the QS system is crucial in the pathogenesis of P. aeruginosa. However, it is unclear whether QS systems of P. aeruginosa play the same role during infections. Methodology: In this study, to explore the contribution of QS systems to the pathogenesis of P. aeruginosa during urinary tract infections, we collected 82 clinical isolates. Detection of N-acyl-homoserine lactones (C12-HSL and C4-HSL) was performed on agar plates employing biosensor strains C. violaceum. Elastase and biofilm production were determined spectrophotometrically. QS genes were detected by PCR and subsequently underwent sequencing. Results and conclusion: Six isolates were found to be negative in the production of both C12-HSL and C4-HSL and all virulence factors tested. PCR analysis of these isolates revealed that four isolates contained all four QS genes while one isolate was negative for lasR gene, and one isolate negative for lasI, lasR and rhlR genes. Sequence analyses of these isolates showed that the lasR, lasI, rhlR and rhlI genes had point mutations. The combination of these mutations probably explains their C12-HSL, C4-HSL and virulence factor deficiencies. Results of this study suggest that QS deficient clinical isolates occur and are still capable of causing clinical infections in humans.

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