Taichi Kashiwagi

Kinetic analysis of superoxide anion radical-scavenging and hydroxyl radical-scavenging activities of platinum nanoparticles

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.

Protective mechanism of reduced water against alloxan-induced pancreatic β-cell damage: Scavenging effect against reactive oxygen species

Reactive oxygen species (ROS) cause irreversible damage to biological macromolecules, resulting in many diseases. Reduced water (RW) such as hydrogen-rich electrolyzed reduced water and natural reduced waters like Hita Tenryosui water in Japan and Nordenau water in Germany that are known to improve various diseases, could protect a hamster pancreatic β cell line, HIT-T15 from alloxan-induced cell damage. Alloxan, a diabetogenic compound, is used to induce type 1 diabetes mellitus in animals. Its diabetogenic effect is exerted via the production of ROS. Alloxan-treated HIT-T15 cells exhibited lowered viability, increased intracellular ROS levels, elevated cytosolic free Ca2+ concentration, DNA fragmentation, decreased intracellular ATP levels and lowering of glucose-stimulated release of insulin. RW completely prevented the generation of alloxan-induced ROS, increase of cytosolic Ca2+ concentration, decrease of intracellular ATP level, and lowering of glucose-stimulated insulin release, and strongly blocked DNA fragmentation, partially suppressing the lowering of viability of alloxan-treated cells. Intracellular ATP levels and glucose-stimulated insulin secretion were increased by RW to 2–3.5 times and 2–4 times, respectively, suggesting that RW enhances the glucose-sensitivity and glucose response of β-cells. The protective activity of RW was stable at 4 °C for over a month, but was lost by autoclaving. These results suggest that RW protects pancreatic β-cells from alloxan-induced cell damage by preventing alloxan-derived ROS generation. RW may be useful in preventing alloxan-induced type 1-diabetes mellitus.

Suppressive effects of electrolyzed reduced water on alloxan-induced apoptosis and type 1 diabetes mellitus

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 β-cells. Here, we showed that electrolyzed reduced water prevented alloxan-induced DNA fragmentation and the production of cells in sub-G1 phase in HIT-T15 pancreatic β-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 β-cells and the development of symptoms in type 1 diabetes model mice by alleviating the alloxan-derived generation of reactive oxygen species.

Electrochemically Reduced Water Protects Neural Cells from Oxidative Damage

Aging-related neurodegenerative disorders are closely associated with mitochondrial dysfunction and oxidative stresses and their incidence tends to increase with aging. Brain is the most vulnerable to reactive species generated by a higher rate of oxygen consumption and glucose utilization compared to other organs. Electrochemically reduced water (ERW) was demonstrated to scavenge reactive oxygen species (ROS) in several cell types. In the present study, the protective effect of ERW against hydrogen peroxide (H2O2) and nitric oxide (NO) was investigated in several rodent neuronal cell lines and primary cells. ERW was found to significantly suppress H2O2 (50–200 μM) induced PC12 and SFME cell deaths. ERW scavenged intracellular ROS and exhibited a protective effect against neuronal network damage caused by 200 μM H2O2 in N1E-115 cells. ERW significantly suppressed NO-induced cytotoxicity in PC12 cells despite the fact that it did not have the ability to scavenge intracellular NO. ERW significantly suppressed both glutamate induced Ca2+ influx and the resulting cytotoxicity in primary cells. These results collectively demonstrated for the first time that ERW protects several types of neuronal cells by scavenging ROS because of the presence of hydrogen and platinum nanoparticles dissolved in ERW.

SUPPRESSION OF CELL GROWTH BY PLATINUM NANOCOLLOIDS AS SCAVENGERS AGAINST REACTIVE OXYGEN SPECIES

Electrolysed-reduced water (ERW) contained Platinum nanocolloids (PtNCs) of 1–10 nm, suggesting that PtNCs in ERW functioned as active hydrogen donors and scavenge intracellular reactive oxygen species (ROS). Electron paramagnetic resonance (EPR) analysis revealed that synthesized PtNCs of about 2 nm scavenged superoxide anion radicals and DPPH radicals. Synthesized PtNCs scavenged intracellular ROS and suppressed the growth of human leukemia K562 cells.

Suppression of Oxidative Stress-Induced Apoptosis of Neuronal Cells by Electrolyzed-Reduced Water

We have proposed an active hydrogen reduced water theory that active hydrogen produced by electrolysis of water is stabilized in the form of hydrogenated metal nanocolloids in electrolyzed reduced water (ERW) and scavenges intracellular reactive oxygen species (ROS). Because various brain diseases are caused by oxygen stress, we examined the effect of ERW on oxidative stress-induced apoptois of neuronal cells. ERW suppressed the H2O2-induced cell death of mouse neuroblastoma N1E115 cells, rat pheochromocytoma PC12 cells and mouse neuronal stem SFME cells. ERW lowered the intracellular ROS level of N1E115 cells, suppressing the H2O2-induced decrease of mitochondrial membrane potential and intracellular ATP level, which are markers of apoptosis. These results suggested the effectiveness of ERW for prevention of various brain diseases caused by oxidative stress.

Erratum to: Suppressive effects of natural reduced waters on alloxan-induced apoptosis and type 1 diabetes mellitus

The original article has been published with an error that is corrected below: Under the heading ‘‘Mineral waters and medium preparation’’ in the section of Materials and methods, the sentence ‘‘NMWs have the following physical properties: for Hita T. W., pH of 7.29 ± 0.02 and Eh of 410.33 ± 10.41 mV’’ should be replaced by ‘‘NMWs have the following physical properties: for Hita T. W., pH of 8.29 ± 0.02 and Eh of 410.33 ± 10.41 mV.’’

Suppression of glutamate-induced neural cell death by electrolyzed-reduced water

Electrolyzed-reduced water (ERW) produced by electrolyzing water in cathode side has the ability to scavenge reactive oxygen species (ROS). Here, we investigated the effect of ERW on oxidative stress-induced neural cell death by glutamate. When cell viability assay was performed using primary rat cerebral cortical culture as neural model, ERW suppressed neural cell death by glutamate. Furthermore, intracellular ROS levels were reduced by ERW, suggesting that suppressive effect of ERW on the glutamate-induced neural cell death was due to the suppression of glutamate-induced ROS augmentation by ERW.