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

The aim is to evaluate the prooxidant and antimicrobial effects of FeO and TiO 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 (HO-FeSO)-for the generation of hydroxyl radicals (OH); chemical, with oxidant hydrogen peroxide (HO); chemical (NAD.H-PhMS), for the generation of superoxide radicals (O). FeO nanoparticles exhibit highly pronounced antioxidant properties; TiO 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 TiO 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 TiO, 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 TiO, but not FeO nanoparticles, showing their antibacterial effect. Thalicarpine, in combination with TiO, showed even synergetic antibacterial effect.