Synthesis, Modification and Characterization of Antimicrobial Textile Surface Containing ZnO Nanoparticles

In this research, a textile surface was modified by the sol–gel methodology with a new antimicrobial coating containing nanoparticles active against bacteria resistant to antibiotics. The effect of ultrasonic irradiation power (40 to 90 kHz), the concentration of reagents (nanoparticles, precursor and acids) and time (15 to 72 min) were investigated in relation to the structure, morphology and antimicrobial activity of coatings with zinc oxide nanoparticles. The relationship between the sonocatalytic performance and structure of the resultant modification was established by using various techniques, such as FTIR spectroscopy (FTIR) and scanning electron microscopy with an EDX detector (SEM-EDX), thin-layer chromatography (TLC) and antimicrobial effects were determined on selected model microorganisms. The homogeneity of layers with ZnO nanoparticles on samples was increased by increasing the ultrasonic irradiation power and time. The ultrasonic irradiation unify did not only unify both the structure and the morphology of samples, it also prevented the agglomeration of the nanoparticles. Moreover, under optimal conditions, an antimicrobial coating with ZnO nanoparticles, active against bacterial species S. aureus and E. coli was efficiently prepared. Results of the Time-kill methodology revieled excellent results starting after 6 hours of exposal to antimicrobialy functionalized cellulose polymer.

Anthraquinone profile, antioxidant and antimicrobial activity of bark extracts of Rhamnus alaternus, R. fallax, R. intermedia and R. pumila

The quantity of phenols, as well as antioxidant and antimicrobial activities, were investigated in bark of Rhamnus alaternus L., R. fallax Boiss., R. intermedia Steud. et Hochst., and R. pumila Turra from natural stands in Croatia. The most abundant anthraquinones in the investigated extracts were chrysophanol in R. alaternus (3.14 mg/g), emodin in R. pumila (0.339 mg/g), and physcion in R. fallax (2.70 mg/g) and R. intermedia (0.285 mg/g). The species exhibiting the highest antioxidant activity were R. fallax and R. pumila. A positive correlation was observed between total phenolic and flavonoid levels of the extracts and antioxidant activity in some of the assays. All species showed antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Aspergillus niger and Microsporum gypseum with minimal inhibitory concentrations equal to or below 2.500 mg/mL. The results indicate that the investigated Rhamnus species are a source of anthraquinones and other phenols, which act as multifunctional antioxidants with antimicrobial activity.

Radioprotective effects of propolis and quercetin in gamma-irradiated mice evaluated by the alkaline comet assay

The radioprotective effects of ethanolic extract of propolis (EEP) and quercetin on the white blood cells of the whole-body irradiated CBA mice were investigated. Irradiation was performed using a gamma-ray source ((60)Co), and absorbed dose was 9 Gy. The efficiency of test components was evaluated when given intraperitoneally (ip) at a dose of 100 mg kg(-1) for 3 consecutive days before and/or after irradiation. Moreover, possible genotoxic effects of test components were also assessed on non-irradiated animals. For each experimental group leukocyte count was determined and the primary DNA damage in leukocytes was assessed using the alkaline comet assay. The higher efficiency of EEP and quercetin was observed when given preventively. The results suggest that propolis and quercetin given to mice before irradiation protect their white blood cells from lethal effects of irradiation and diminish primary DNA damage as confirmed by the alkaline comet assay. Positive results obtained on gamma-irradiated mice given EEP and quercetin, complementary with our earlier observations on survival of irradiated mice, indicate that these compounds could be considered effective non-toxic radioprotectors. The exact mechanisms of radioprotection by these compounds and their effects on DNA repair processes are still to be elucidated.

Antifungal activity of thyme (Thymus vulgaris L.) essential oil and thymol against moulds from damp dwellings

AIMS

To characterize antifungal activities of essential oil of thyme (Thymus vulgaris L.) and pure thymol, as comparative substance, on different mould species isolated from damp dwellings.

METHODS AND RESULTS

Fifty samples of wall scrapes were collected from damp dwellings in Zagreb, the capital of Croatia. The members of the following mould genera were recovered from the samples: Aspergillus (44%), Penicillium (18%) Alternaria, Ulocladium, Absidia and Mucor (8%) Cladosporium, Trichoderma and Rhizopus (6%), and Chaetomium (2%). Two strains of Stachybotrys chartarum were isolated from damp dwellings in Slovakia. Antifungal activities of the thyme essential oil, which contains p-cymene (36.5%), thymol (33.0%) and 1,8-cineole (11.3%) as main components, and pure thymol were determined by the dilution method and exposure to vaporous phase of the oil. Minimum inhibitory concentrations (MIC) of both thymol and essential oil were bellow 20 microg ml(-1), except for Mucor spp. (50.20 microg ml(-1)). Thymol exhibited approximately three-times stronger inhibition than essential oil of thyme. The vaporous phase of the thyme essential oil (82 microg l(-1)) in glass chambers strongly suppressed the sporulation of moulds during 60 days of exposure.

CONCLUSION

The thyme essential oil possesses a wide range spectrum of fungicidal activity. The vaporous phase of the oil exhibited long-lasting suppressive activity on moulds from damp dwellings.

SIGNIFICANCE AND IMPACT OF THE STUDY

Essential oil of thyme and thymol could be used for disinfection of mouldy walls in the dwellings in low concentration.