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Nanoparticle-specific changes in Arabidopsis thaliana gene expression after exposure to ZnO, TiO2, and fullerene soot

The effect of exposure to 100 mg/L zinc oxide (nZnO), fullerene soot (FS) or titanium dioxide (nTiO(2)) nanoparticles on gene expression in Arabidopsis thaliana roots was studied using microarrays. After 7d, nZnO, FS, or nTiO(2) exposure resulted in 660 up- and 826 down-regulated genes, 232 up- and 189 down-regulated genes, and 80 up- and 74 down-regulated genes, respectively (expression difference>2-fold; p[t test]<0.05). The genes induced by nZnO and FS include mainly ontology groups annotated as stress responsive, including both abiotic (oxidative, salt, water deprivation) and biotic (wounding and defense to pathogens) stimuli. The down-regulated genes upon nZnO exposure were involved in cell organization and biogenesis, including translation, nucleosome assembly and microtubule based process. FS largely repressed the transcription of genes involved in electron transport and energy pathways. Only mild changes in gene expression were observed upon nTiO(2) exposure, which resulted in up- and down-regulation of genes involved mainly in responses to biotic and abiotic stimuli. The data clearly indicate that the mechanisms of phytotoxicity are highly nanoparticle dependent despite of a limited overlap in gene expression response.

In vitro anti-inflammatory activity of carvacrol: Inhibitory effect on COX-2 catalyzed prostaglandin E2 biosynthesisb

Possible anti-inflammatory effect of carvacrol was evaluated by in vitro cyclooxygenase-2 (COX-2) assay. Carvacrol inhibited production of prostaglandin E2 catalysed by COX-2 with an IC50 value of 0.8 μM what is practically the same concentration as the IC50 obtained for the standard inhibitors indomethacin and NS-398 with values of 0.7 μM and 0.8 μM, respectively. The COX-1 was inhibited approximately at the same rate (IC50 of 0.7 μM for carvacrol), which suggests non-selective inhibition of both enzyme isoforms. The results of the study demonstrate possible anti-inflammatory potential of this compound due to the inhibition of inducible COX-2 isoform.

Evaluation of Antimicrobial and Anti-Inflammatory Activities of Seed Extracts from Six Nigella Species

Seed extracts from six species of the genus Nigella (Family Ranunculaceae)-Nigella arvensis, Nigella damascena, Nigella hispanica, Nigella nigellastrum, Nigella orientalis, and Nigella sativa-obtained by successive extraction with n-hexane, chloroform, and methanol, were tested for their antimicrobial activity against 10 strains of pathogenic bacteria and yeast using the microdilution method as well as for anti-inflammatory properties by in vitro cyclooxygenase (COX)-1 and COX-2 assay. Chemical characterization of active extracts was carried out including free and fixed fatty acid analysis. Comparison of antimicrobial activity showed that N. arvensis chloroform extract was the most potent among all species tested, inhibiting Gram-positive bacterial and yeast strains with minimum inhibitory concentration (MIC) values ranging from 0.25 to 1 mg/mL. With the exception of selective inhibitory action of n-hexane extract of N. orientalis on growth of Bacteroides fragilis (MIC = 0.5 mg/mL), we observed no antimicrobial activity for other Nigella species. Anti-inflammatory screening revealed that N. sativa, N. orientalis, N. hispanica, N. arvensis n-hexane, and N. hispanica chloroform extracts had strong inhibitory activity (more than 80%) on COX-1 and N. orientalis, N. arvensis, and N. hispanica n-hexane extracts were most effective against COX-2, when the concentration of extracts was 100 microg/mL in both COX assays. In conclusion, N. arvensis, N. orientalis, and N. hispanica seeds, for the first time examined for antimicrobial and anti-inflammatory effects, revealed their significant activity in one or both assays.

The Transcriptomic Response of Arabidopsis thaliana to Zinc Oxide: A Comparison of the Impact of Nanoparticle, Bulk, and Ionic Zinc

The impact of nanosize was evaluated by comparing of the transcriptomic response of Arabidopsis thaliana roots to ZnO nanoparticles (nZnO), bulk ZnO, and ionic Zn(2+). Microarray analyses revealed 416 up- and 961 down-regulated transcripts (expression difference >2-fold, p [FDR] < 0.01) after a seven-day treatment with nZnO (average particle size 20 nm, concentration 4 mg L(-1)). Exposure to bulk ZnO resulted in 816 up- and 2179 down-regulated transcripts. The most dramatic changes (1711 transcripts up- and 3242 down-regulated) were caused by the presence of ionic Zn(2+) (applied as ZnSO4.7H20 at a concentration of 14.14 mg L(-1), corresponding to the amount of Zn contained in 4 mg L(-1) ZnO). Genes involved in stress response (e.g., to salt, osmotic stress or water deprivation) were the most relatively abundant group of gene transcripts up-regulated by all three Zn treatments while genes involved in cell organization and biogenesis (e.g., tubulins, arabinogalactan proteins) and DNA or RNA metabolism (e.g., histones) were the most relatively abundant groups of down-regulated transcripts. The similarity of the transcription profiles and the increasing number of changed transcripts correlating with the increased concentration of Zn(2+) in cultivation medium indicated that released Zn(2+) may substantially contribute to the toxic effect of nZnO because particle size has not demonstrated a decisive role.

Anti-inflammatory activity of natural stilbenoids: A review

Graphical abstract Figure. No caption available. ABSTRACT Resveratrol and other natural stilbenoids, including piceatannol, pterostilbene, and gnetol, are well‐known anti‐inflammatory compounds with indisputable activity in vitro as well as in vivo. Their molecular targets include inducible nitric oxide synthase, cyclooxygenases, leukotrienes, nuclear factor kappa B, tumor necrosis factor &agr;, interleukins and many more. This anti‐inflammatory activity together with their antioxidant activity is believed to stand behind their other positive health effects against cancer, cardiovascular and neurodegenerative diseases or diabetes. Thus, they are nowadays commercially marketed as nutraceuticals. Naturally, they are present in wine, grapes or berries. However, there is a rigorous debate about the real effect of these compounds on human health. It is argued that the concentration of stilbenoids in food and beverages is too low to have any therapeutic potential and this concentration is further reduced by their low bioavailability and extensive metabolism. Therefore, this review focuses on in vitro, in vivo, preclinical as well as clinical data available for various natural stilbenoids and summarizes the anti‐inflammatory targets on molecular level, compares the relevance of the experimental studies, discusses the metabolism of stilbenoids and the potential activity of their metabolites and relates this knowledge to human health. Moreover, the ways to augment stilbenoidsí efficacy are suggested with special focus on multitargeted therapy and nanocarriers.

Impact of Wines and Wine Constituents on Cyclooxygenase-1, Cyclooxygenase-2, and 5-Lipoxygenase Catalytic Activity

Cyclooxygenases and lipoxygenases are proinflammatory enzymes; the former affects platelet aggregation, vasoconstriction, vasodilatation and later the development of atherosclerosis. Red wines from Georgia and central and western Europe inhibited cyclooxygenase-1 (COX-1) activity in the range of 63–94%, cyclooxygenase-2 (COX-2) activity in the range of 20–44% (tested at a concentration of 5 mL/L), and 5-lipoxygenase (5-LOX) activity in the range of 72–84% (at a concentration of 18.87 mL/L). White wines inhibited 5-LOX in the range of 41–68% at a concentration of 18.87 mL/L and did not inhibit COX-1 and COX-2. Piceatannol (IC50 = 0.76 μM) was identified as a strong inhibitor of 5-LOX followed by luteolin (IC50 = 2.25 μM), quercetin (IC50 = 3.29 μM), and myricetin (IC50 = 4.02 μM). trans-Resveratrol was identified as an inhibitor of COX-1 (IC50 = 2.27 μM) and COX-2 (IC50 = 3.40 μM). Red wine as a complex mixture is a powerful inhibitor of COX-1, COX-2, and 5-LOX, the enzymes involved in eicosanoid biosynthetic pathway.

Redox and non-redox mechanism of in vitro cyclooxygenase inhibition by natural quinones.

In this study, ten anthra-, nine naphtho-, and five benzoquinone compounds of natural origin and five synthetic naphthoquinones were assessed, using an enzymatic in vitro assay, for their potential to inhibit cyclooxygenase-1 and -2 (COX-1 and COX-2), the key enzymes of the arachidonic acid cascade. IC₅₀ values comparable with COX reference inhibitor indomethacin were recorded for several quinones (primin, alkannin, diospyrin, juglone, 7-methyljuglone, and shikonin). For some of the compounds, we suggest the redox potential of quinones as the mechanism responsible for in vitro COX inhibition because of the quantitative correlation with their pro-oxidant effect. Structure-relationship activity studies revealed that the substitutions at positions 2 and 5 play the key roles in the COX inhibitory and pro-oxidant actions of naphthoquinones. In contrast, the redox mechanism alone could not explain the activity of primin, embelin, alkannin, and diospyrin. For these four quinones, molecular modeling suggested similar binding modes as for conventional nonsteroidal anti-inflammatory drugs (NSAIDs).

In vitro anti-microbial activity of extracts from the callus cultures of some Nigella species

Crude methanol extracts from callus cultures of Nigella arvensis, N. damascena, N. hispanica, N. integrifolia, and N. sativa were investigated for their anti-microbial activity. Growth inhibition was determined in Gram-positive and Gram-negative bacterial strains as well as in yeast by using a broth-microdilution method. The results showed that the extracts of all calli tested exhibited significant anti-microbial activity, especially against Bacillus cereus, Staphylococcus aureus and Staphylococcus epidermidis. Compared with other Nigella species, a callus culture of N. hispanica was the most effective against the microorganisms used in this study.

Prospective performance evaluation of selected common virtual screening tools. Case study: Cyclooxygenase (COX) 1 and 2.

Computational methods can be applied in drug development for the identification of novel lead candidates, but also for the prediction of pharmacokinetic properties and potential adverse effects, thereby aiding to prioritize and identify the most promising compounds. In principle, several techniques are available for this purpose, however, which one is the most suitable for a specific research objective still requires further investigation. Within this study, the performance of several programs, representing common virtual screening methods, was compared in a prospective manner. First, we selected top-ranked virtual screening hits from the three methods pharmacophore modeling, shape-based modeling, and docking. For comparison, these hits were then additionally predicted by external pharmacophore- and 2D similarity-based bioactivity profiling tools. Subsequently, the biological activities of the selected hits were assessed in vitro, which allowed for evaluating and comparing the prospective performance of the applied tools. Although all methods performed well, considerable differences were observed concerning hit rates, true positive and true negative hits, and hitlist composition. Our results suggest that a rational selection of the applied method represents a powerful strategy to maximize the success of a research project, tightly linked to its aims. We employed cyclooxygenase as application example, however, the focus of this study lied on highlighting the differences in the virtual screening tool performances and not in the identification of novel COX-inhibitors.

Effect of Metal Oxides on Plant Germination: Phytotoxicity of Nanoparticles, Bulk Materials, and Metal Ions

The recent rapid expansion of nanotechnologies has increased concern over the impact of engineered nanoparticles (ENPs) on the environment and biota. Although the toxicity of ENPs has received considerable attention in the recent years, there are still gaps in our knowledge of the mechanisms responsible for their effects. In this study, we tested the toxicity of various metal oxide ENPs (Al2O3, CuO, Fe3O4, MnO, TiO2, and ZnO), including nanowires together with their bulk counter particles and soluble metal salts, on germinating seeds of Sinapis alba L. Fe3O4, TiO2, MnO2, and Al2O3 ENPs did not negatively affected seed germination at any tested concentrations. However, CuO and ZnO ENPs showed a dose-dependent inhibition of germination. Metal ions were more toxic than metal oxide particles at corresponding concentrations. The highest toxicity was exhibited by Cu, followed by Zn, Fe, Al, and Mn ions. A comparison of ENPs with bulk materials did not reveal significantly higher ENP toxicity. Similarly, nanowires showed effects similar to other nanoparticles and bulk materials. Our results indicate that the nanosize or shape of particles did not play a crucial role, whereas metal ions released into cultivation media and accumulated in seedlings contributed significantly to the phytotoxicity of metal oxides.