There are few reports on the physiological effects of metal nanoparticles (nps), especially with respect to their functions as scavengers for superoxide anion radical (O2(.-)) and hydroxyl radical (.OH). We tried to detect the scavenging activity of Pt nps using a hypoxanthine-xanthine oxidase system for O2(.-) and using a Fenton and a UV/H2O2 system for .OH. Electron spin resonance analysis revealed that 2 nm particle size Pt nps have the ability to scavenge O2(.-) and .OH. The calculated rate constant for the O2(.-)-scavenging reaction was 5.03 +/- 0.03 x 10(7) M (-1) s (-1). However, the analysis of the Fenton and UV/H 2O 2 system in the presence of Pt nps suggested that the .OH-scavenging reaction cannot be determined in both systems. Among particle sizes tested from 1 to 5 nm, 1 nm Pt nps showed the highest O2(.-)-scavenging ability. Almost no cytotoxicity was observed even after adherent cells (TIG-1, HeLa, HepG2, WI-38, and MRC-5) were exposed to Pt nps at concentrations as high as 50 mg/L. Pt nps scavenged intrinsically generated reactive oxygen species (ROS) in HeLa cells. Additionally, Pt nps significantly reduced the levels of intracellular O2(.-) generated by UVA irradiation and subsequently protected HeLa cells from ROS damage-induced cell death. These findings suggest that Pt nps may be a new type of antioxidant capable of circumventing the paradoxical effects of conventional antioxidants.
Tumor angiogenesis, the formation of new blood capillaries by vascular endothelial cells from existing vessels, is an important mechanism for supplying nutrients, oxygen, growth factors and others to tumor cells. Tumor cells trigger angiogenesis by secreting angiogenic factors, especially vascular endothelial growth factor (VEGF-A), 1) which plays an important role in the regulation of normal and abnormal angiogenesis.2) VEGF-A (commonly known as VEGF) was first reported as a vascular permeability-inducing factor secreted by tumor cells, and referred to as vascular permeability factor (VPF). Reactive oxygen species (ROS) are suggested to play an important role in angiogenesis. 10) Furthermore, there is increasing evidence of the involvement of H 2 O 2 in the regulation of angiogenesis.9,11-13) As well, a variety of cell lines derived from human tumors has been shown to produce large amounts of H 2 O 2 .14) Constitutive surveillance for cellular protection against oxidative stress is conferred by intracellular antioxidative agents.15) Excess amounts of ROS are toxic and cause a reduction of intracellular antioxidant levels.16) It has been reported that pretreatment of the heart with exogenous antioxidants improved its condition as a result of reducing ROS production.17) The VEGF-A gene is one that has its expression regulated by ROS, especially by H 2 O 2 . Additional data support that VEGF-A mRNA is up-regulated by H 2 O 2 in a dose-and time-dependent manner. 18,19) Taken together, these suggest that some endogenous as well as exogenous antioxidative agents can be used to regulate VEGF-A gene expression and/or H 2 O 2 production for therapeutic purposes.Electrolyzed reduced water (ERW) has attracted much attention because of its antioxidative potential. Water electrolysis typically produces two forms of water: reduced or alkaline (high pH) water near the cathode and an oxidized or acid (low pH) water near the anode. Applications of oxidized
Electrolyzed reduced water, which is capable of scavenging reactive oxygen species, is attracting recent attention because it has shown improved efficacy against several types of diseases including diabetes mellitus. Alloxan produces reactive oxygen species and causes type 1 diabetes mellitus in experimental animals by irreversible oxidative damage to insulin-producing b-cells. Here, we showed that electrolyzed reduced water prevented alloxaninduced DNA fragmentation and the production of cells in sub-G1 phase in HIT-T15 pancreatic b-cells. Blood glucose levels in alloxan-induced type 1 diabetes model mice were also significantly suppressed by feeding the mice with electrolyzed reduced water. These results suggest that electrolyzed reduced water can prevent apoptosis of pancreatic b-cells and the development of symptoms in type 1 diabetes model mice by alleviating the alloxan-derived generation of reactive oxygen species.Keywords Electrolyzed reduced water Á Alloxan Á Type 1 diabetes mellitus Á Reactive oxygen species Á HIT-T15 cells
Electrochemically reduced water (ERW) is produced near a cathode during electrolysis and exhibits an alkaline pH, contains richly dissolved hydrogen, and contains a small amount of platinum nanoparticles. ERW has reactive oxygen species (ROS)-scavenging activity and recent studies demonstrated that hydrogen-dissolved water exhibits ROS-scavenging activity. Thus, the antioxidative capacity of ERW is postulated to be dependent on the presence of hydrogen levels; however, there is no report verifying the role of dissolved hydrogen in ERW. In this report, we clarify whether the responsive factor for antioxidative activity in ERW is dissolved hydrogen. The intracellular ROS scavenging activity of ERW and hydrogen-dissolved water was tested by both fluorescent stain method and immuno spin trapping assay. We confirm that ERW possessed electrolysis intensity-dependent intracellular ROS-scavenging activity, and ERW exerts significantly superior ROS-scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water. ERW retained its ROS-scavenging activity after removal of dissolved hydrogen, but lost its activity when autoclaved. An oxygen radical absorbance capacity assay, the 2,2-diphenyl-1-picrylhydrazyl assay and chemiluminescence assay could not detect radical-scavenging activity in both ERW and hydrogen-dissolved water. These results indicate that ERW contains electrolysis-dependent hydrogen and an additional antioxidative factor predicted to be platinum nanoparticles.
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