International Congress on Occupational & Environmental Toxicology - ICOETox 2016
Abstract
Ascorbic acid (AA) is a standard antioxidant and its radical scavenging properties also appear to be responsible for its antigenotoxic properties. Nanoparticle-mediated delivery of antioxidant compounds is intended to increase their bioavailability while maintaining their effectiveness. Colloids consisting of the 45-Å TiO2 nanoparticles (NPs) with anatase crystal structure were prepared by acidic hydrolysis of TiCl4. The synthesized TiO2 NPs were characterized using transmission electron microscopy and X-ray diffraction analysis. The charge transfer (CT) complex formation between surface Ti atoms and AA is indicated by immediate appearance of red color. The aim of this study was to compare, for the first time, the antioxidant and antigenotoxic effects of AA attached to the surface of TiO2 NPs with free AA in a wide concentration range. For evaluation of antigenotoxic properties whole blood cells were first treated with 50 μM H2O2 to induce DNA damage, and then exposed to 3 different concentrations of free AA (1.3×10-2, 2.6×10-2, and 3.9×10-2 M) and the same concentrations of AA attached to TiO2 NPs (0.05, 0.1, and 0.15 M) for 30 min at 37 0C. The level of DNA damage was evaluated by comet assay method. For evaluation of antioxidant properties, total antioxidant capacity (TAC), total antioxidative status (TAS) and prooxidative-antioxidative balance (PAB) were determined in human serum pool during 2 and 24 h incubation at 37 °C, without and with terc-buthyl-hydroperoxide (TBH) as exogenously added oxidant. As expected, the results of DNA damage showed that the increase of AA concentration leads to a reduction of DNA damage. The similar concentration dependence was observed for surface-modified TiO2 NPs with AA. So, no significant differences between the antigenotoxic properties of free AA and AA attached to the TiO2 NPs were noticed, but only the highest concentrations showed significant effect in both experimental treatments. Regarding short-term oxidative balance in biological material (serum), during 2h, by measuring the TAC we have showed that the complex NP and AA, so as ascorbic acid showed a significant increase in TAC capacity, compared to native serum. This increase of antioxidative capacity couldn’t be abrogated even with a powerful oxidant, terc-buthylhydroperoxide presence (TBH). After 24h hour incubation the TAC level in both samples decreased towards the baseline level. About the TOS, which measures all oxidative components in plasma such as hydrogen-peroxide and lipid hydroperoxide, the complex of NP and AA versus AA alone showed inconsistent results. Prooxidative-antioxidative balance (PAB) measuring equilibrium between oxidants and antioxidants remains low, almost imponderable after 2h and after 24h serum incubation with the two substances. To summarize, we suggest that surface-modified TiO2 NPs with AA and/or similar compounds can be used to improve their bioavailability while maintaining its beneficial activities.3rd International Congress on Occupational & Environmental Toxicology - ICOETox 2016 and 3rd Ibero-American Meeting on Toxicology and Environmental Health International (IBAMTOX 2016), 21-23 June 2016 | Port
