Investigation of Biological and Prooxidant Activity of Zinc Oxide Nanoclusters and Nanoparticles.

Zinc oxide (ZnO) nanomaterials offer some promising antibacterial effects. In this study, a new form of ZnO is synthesized, named ZnO nanocluster bars (NCs). Herein, ZnO NCs, ZnO nanoparticles (NPs), ZnO coated with silica (ZnO-SiOA, ZnO-SiOB), and SiO2 NPs were prepared, characterized, and their antimicrobial and prooxidant activity were tested. The prooxidant activity of all nanomaterials was studied according to free-radical oxidation reactions (pH 7.4 and pH 8.5) in chemiluminescent model systems. Each form of new synthesized ZnO nanomaterials exhibited a unique behavior that varied from mild to strong prooxidant properties in the Fenton`s system. ZnO NPs and ZnO NCs showed strong antibacterial effects, ZnO-SiOA NPs did not show any antibacterial activity representing biocompatibility. All tested NMs also underwent oxidation by H2O2. ZnO NCs and ZnO NPs exhibited strong oxidation at pH 8.5 in the O2-. generating system. While, SiO2, ZnO-SiOA andZnO-SiOB possessed pronounced 60-80% antioxidant effects, SiO2 NPs acted as a definitive prooxidant which was not observed in other tests. ZnO NCs are strong oxidized, assuming that ZnO NCs provide a slower release of ZnO, which leads to having a stronger effect on bacterial strains.  Thus, ZnO NCs are an important antibacterial agent that could be an emergent replacement of traditional antibiotics.

Prooxidant and antimicrobic effects of iron and titanium oxide nanoparticles and thalicarpine.

The aim is to evaluate the prooxidant and antimicrobial effects of Fe3O4 and TiO2 nanoparticles and thalicarpine by luminescent and standard microbiological assays. Their effect on the kinetics of free-radical oxidation reactions (at pH 7.4 and pH 8.5) is studied in the following model systems, using activated chemiluminescence: chemical, with Fenton's reagent (H2O2-FeSO4)-for the generation of hydroxyl radicals (.OH); chemical, with oxidant hydrogen peroxide (H2O2); chemical (NAD.H-PhMS), for the generation of superoxide radicals (O2.-). Fe3O4 nanoparticles exhibit highly pronounced antioxidant properties; TiO2 nanoparticles exhibit mild to moderate prooxidant properties at neutral and alkaline conditions. Those properties are tested by the chemiluminescent method for the first time. Thalicarpine and its combination with TiO2 nanoparticles exhibit pronounced antioxidant activities at pH 8.5 which are lost and transformed into well-presented prooxidant effects at pH 7.4. That is a result-supported proof on the observed typical properties of thalicarpine and TiO2, namely antibacterial, organic-preserving and anti-pathogenic activities. The antimicrobial effect is tested on Gram-positive and Gram-negative bacteria: two strains of Escherichia coli, Bacillus cereus 1095 and Staphylococcus aureus. All bacteria are destroyed after the application of TiO2, but not Fe3O4 nanoparticles, showing their antibacterial effect. Thalicarpine, in combination with TiO2, showed even synergetic antibacterial effect.

Antibacterial effect of TiO2 :Cu:Ag thin coatings on Pseudomonas strain measured by microbiological and ATP assays.

The aim of this study is to investigate the antimicrobial properties of nanocomposite thin TiO2 :Cu:Ag films on Pseudomonas putida as a natural isolate and an opportunistic pathogen. Several different methods were used to compare the antibacterial effect of thin TiO2 :Cu:Ag layers obtained by radiofrequency magnetron sputter deposition against P. putida: optical density of the bacterial suspension, most probable number of survived cells, dehydrogenase activity inhibition, scanning electron microscopy images, atomic flame absorption spectroscopy, and adenosine triphosphate (ATP) luminescent assay. Optical density measurements and most probable plate count were in agreement and showed a strong bactericidal effect of the as-deposited and only bacteriostatic effect of the annealed coatings with the same metal content on tested bacteria. As the metal quantity in the medium rises during the first hour of the experiment, it could be suggested that this is the main reason for cell death. ATP-luminescent assay showed up to 18-fold reduction of the signal. It was compared with other microbiological and biochemical assays to prove the strong antibacterial effect of nanocomposite thin TiO2 :Cu:Ag coatings with the possibilities of medical applications. Protection of medical devices against infections is a significant current challenge raised by an increasing number of medical devices-associated infections and microbial resistance to conventional antibiotic and multidrug treatments. Deposition of antimicrobial coatings is one of the current approaches to mitigate the problem.

Combined efficacy of oseltamivir, isoprinosine and ellagic acid in influenza A(H3N2)-infected mice.

Influenza pathogenesis comprises a complex cascade of impaired cellular processes resulting from the viral replication and exaggerated immune response accompanied by reactive oxygen species (ROS) burst and oxidative stress, destructing membranous structures and tissues. By classical virological and biochemical methods we compared and evaluated the therapeutic effects of 2.5mg/kg/day of the antiviral drug - oseltamivir (OS), 500mg/kg/day of the immune modulator - isoprinosine (IP) and 500mg/kg/day of the antioxidant agent ellagic acid (EA) with a focus on their combined activities in influenza H3N2 virus-infected mice. The survival, lung pathology and titers, as well as the oxidative stress biomarker thiobarbituric acid reactive substances (TBARS) in the lungs, liver and blood plasma, correlated to the activities of the antioxidant enzymes superoxide dismutase (SOD) and glutathione reductase (GR) were assessed. We found that the viral inhibitor applied together with the immune modulator and the antioxidant exhibited strong therapeutic effects on the survival of the influenza-challenged mice. That effect was mostly pronounced for the triple combination - protection index (PI) of 75.2%, mean survival time (MST) extended by 5.8 days compared to the PBS control and significant reduction of the lung titers by 1.38 Δlg; 2.3 scores lower lung pathology and 8 times reduction of the accumulated TBARS in the lungs and liver on the 5-th day p.i. The enzymatic assays revealed that this combination demonstrated very good protection against the damaging superoxide radicals (83% efficiency of SOD, in comparison to healthy controls 100%). The double combinations of OS with IP and EA also showed protective effects according to the virological analysis - PI of 53.1% and 54.5%. Ten times higher GR activity was observed when the combination EA+OS and monotherapy of EA were applied (96% in comparison to healthy controls 100%). The best antioxidant effect in blood plasma was observed in the EA+IP group - 4 times reduction in the TBARS-content compared to infected controls but it did not have any efficacy on the survival and lung injury.

Comparative study on the antioxidant capacities of synthetic influenza inhibitors and ellagic acid in model systems.

This study compares the antioxidant capacities in vitro of several synthetic and natural compounds applied and researched for influenza treatment - oseltamivir, isoprinosine, ellagic acid, vitamin E and vitamin C. Three chemical systems are utilized for the generation of reactive oxygen species (ROS) at pH 7.4 and pH 8.5: (1) Fenton's (Fe2++H2O2) for OH and -OH species (2) H2O2 (3) NADH-phenazinemethosulfat, for superoxide radicals (O2-). The kinetics was evaluated by lucigenin-enhanced chemiluminescence. The calculated constants of inhibition k7 describe the antioxidant capacity at the moment of oxidative burst. Their values do not necessarily correspond to the calculated total antioxidant activity. The obtained results revealed that the synthetic anti-influenza drugs (oseltamivir and isoprinosine) as well as ellagic acid possess pronounced scavenging properties mostly against superoxide radicals, comparable and higher than that of traditional natural antioxidants. Quantitative analysis of the antioxidant effects of the examined synthetic substances was performed. The results compared the corresponding effect of the average physiological concentrations and the applied therapeutic antioxidant dose. With these experiments we registered new aspects of their therapeutic activities, due to antioxidant properties against hydroxyl, superoxide radicals and H2O2 oxidation.

Effects of rutin and quercetin on monooxygenase activities in experimental influenza virus infection.

The aim of this work is to study the effect of the flavonoids rutin and quercetin on hepatic monooxygenase activities in experimental influenza virus infection (EIVI). EIVI causes oxidative stress in the whole organism. This is confirmed by the rapidly increased concentrations of thiobarbituric reactive substances in influenza-infected mice: lungs - 290%; blood plasma - more than 320%; liver - 230%; brain - 50%. Although known for their antioxidant activities, rutin and quercetin exhibit prooxidant effect in healthy and antioxidant activity in influenza-infected animals. The pretreatment with both flavonoids (20 mg/kg b.w.) restores oxidative damage mostly in the target organ of the infection as well as in the liver of all infected mice (lungs: rutin - 30%, quercetin - 40%, combination - 45%; liver: rutin - 12%; quercetin - 40%; combination - 50%). As far as EIVI causes oxidative stress, toxicosis and inhibition of the hepatic monooxygenase activity, it is important to study the effects of rutin and quercetin on these systems. Both flavonoids induce the level of cytochrome P-450 (rutin - 13%, quercetin - 30%, combination - 22%) but inactivate NADPH-cytochrome c reductase, aminopyrine N-demethylase and analgin N-demethylase on the 5th day of EIVI. Probably, these flavonoids affect different components of the monooxygenase system. These effects could be explained with oxidative hepatic intoxication on the 5th critical day of EIVI as well as higher dose treatment. More data are needed on the antioxidant/prooxidant effects of rutin and quercetin, probably due to specific metabolic and physiological activities, chemical structure, etc.