Resveratrol/Selenium Nanocomposite with Antioxidative and Antibacterial Properties.

In this work, we synthesized a new composite material comprised of previously formulated resveratrol nanobelt-like particles (ResNPs) and selenium nanoparticles (SeNPs), namely ResSeNPs. Characterization was provided by FESEM and optical microscopy, as well as by UV-Vis and FTIR spectroscopy, the last showing hydrogen bonds between ResNPs and SeNPs. DPPH, TBA, and FRAP assays showed excellent antioxidative abilities with ResNPs and SeNPs contributing mainly to lipid peroxidation inhibition and reducing/scavenging activity, respectively. The antibacterial effect against common medicinal implant colonizers pointed to notably higher activity against Staphylococcus isolates (minimal inhibitory concentrations 0.75-1.5%) compared to tested gram-negative species (Escherichia coli and Pseudomonas aeruginosa). Antibiofilm activity against S. aureus, S. epidermidis, and P. aeruginosa determined in a crystal violet assay was promising (up to 69%), but monitoring of selected biofilm-related gene expression (pelA and algD) indicated the necessity of the involvement of a larger number of genes in the analysis in order to further establish the underlying mechanism. Although biocompatibility screening showed some cytotoxicity and genotoxicity in MTT and alkaline comet assays, respectively, it is important to note that active antioxidative and antibacterial/antibiofilm concentrations were non-cytotoxic and non-genotoxic in normal MRC-5 cells. These results encourage further composite improvements and investigation in order to adapt it for specific biomedical purposes.

Could alder buckthorn (Frangula alnus Mill) be a source of chemotherapeutics effective against hepato- and colorectal carcinoma? An in vitro study.

Among numerous types of cancer, hepatocellular and colorectal carcinoma are important causes of mortality. Given the nature of these cancer types and their resistance, it is of great importance to find new chemotherapeutics and therapy targets, so plant products seem to be an excellent choice in such search. The main goal of this study was to investigate anticancer activity of Frangula alnus ethyl-acetate extract (FA) and its dominant constituent emodin (E) on hepatocellular and colorectal carcinoma cell lines, HepG2 and HCT116, as well as on normal MRC-5 fibroblasts. Cytotoxicity was investigated in MTT test and both FA and E showed strong reduction of cell viability in cancer cells. Flow cytometer analysis demonstrated that FA and E led to G1 phase arrest and slight accumulation of cells in the G2/M phase; additionally, annexinV-FITC/7AAD dying showed that FA and E decreased cell viability and triggered apoptosis in all cell lines. FA and E evidenced strong genotoxic potential in comet assay performed on all cell lines, while tests measuring antioxidative potential (DPPH and TBA) demonstrated strong effect of FA. It could be concluded that both FA and E have significant anticancer activity against hepatocellular and colorectal carcinoma cell lines HepG2 and HCT116, but notable selectivity was not observed.

Cinnamon essential oil and its emulsion as efficient antibiofilm agents to combat Acinetobacter baumannii.

Acinetobacter baumannii is an emerging nosocomial pathogen resistant to a wide spectrum of antibiotics, with great potential to form a biofilm, which further aggravates treatment of infections caused by it. Therefore, searching for new potent agents that are efficient against A. baumannii seems to be a necessity. One of them, which has already been proven to possess a wide spectrum of biological activities, including antimicrobial effect, is cinnamon essential oil. Still, further increase of antibacterial efficacy and improvement of bioavailability of cinnamon oil is possible by emulsification process. The aim of this study was comparative analysis of cinnamon essential oil and its emulsion against biofilm forming A. baumannii clinical isolates. Furthermore, the investigation of toxicological aspects of possible applications of essential oil and emulsion was done as well. Gas chromatography-mass spectrometry of essential oil indicated trans-cinnamaldehyde as the most abundant component. The cinnamon emulsion was synthesized from cinnamon essential oil by combining modified low- and high- energy methods. Synthesized emulsion was characterized with Fourier-transform infrared spectroscopy and photon correlation spectroscopy. Both substances exhibited significant antibacterial (minimal inhibitory concentrations in the range 0.125-0.5 mg/ml) and antibiofilm effects (inhibitions of formation and reduction of pre-formed biofilm were 47-81 and 30-62%, respectively). Compared to essential oil, the efficacy of emulsion was even stronger considering the small share of pure oil (20%) in the emulsion. The result of biofilm eradication assay was confirmed by scanning electron microscopy. Even though the cytotoxicity was high especially for the emulsion, genotoxicity was not determined. In conclusion, strong antibacterial/antibiofilm effect against A. baumannii of the cinnamon essential oil and the fact that emulsification even potentiated the activity, seems to be of great significance. Observed cytotoxicity implicated that further analysis is needed in order to clearly determine active principles being responsible for obtained antibacterial/antibiofilm and cytotoxic properties.

Elucidating the antibiofilm activity of Frangula emodin against Staphylococcus aureus biofilms.

AIMS: Because the Staphylococcus aureus is one of the most well-known pathogens associated with medical devices and nosocomial infections, the aim of the study was to examine antibiofilm potential of emodin against it. METHODS AND RESULTS: Antibacterial activity was examined through microdilution assay. Antibiofilm testing included crystal violet staining of biofilm biomass and morphology analysis by Atomic force microscopy (AFM). Furthermore, aerobic respiration was monitored using the Micro-Oxymax respirometer. For investigation of gene expression qRT-PCR was performed. Emodin demonstrated strong antibacterial activity and ability to inhibit biofilm formation of all tested strains. The effect on preformed biofilms was spotted in few strains. AFM revealed that emodin affects biofilm structure and roughness. Monitoring of respiration under emodin treatment in planktonic and biofilm form revealed that emodin influenced aerobic respiration. Moreover, qRT-PCR showed that emodin modulates expression of icaA, icaD, srrA and srrB genes, as well as RNAIII, and that this activity was strain-specific. CONCLUSION: The results obtained in this study indicate the novel antibiofilm activity of emodin and its multiple pathways of action. SIGNIFICANCE AND IMPACT OF STUDY: This is the first study that examined pathways through which emodin expressed its antibiofilm activity.