Hironobu Murase

Synthesis of a novel vitamin E derivative, 2-(α-d-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol, by α-glucosidase-catalyzed transglycosylation

A novel derivative of vitamin E, vitamin E glucoside, was synthesized from 2-hydroxymethyl-2,5,7,8-tetramethylchroman-6-ol and maltose in a solution containing DMSO by transglycosylation with α-glucosidase from Saccharomyces species. The glycosylated product was identified as 2-(α-d-glucopyranosyl)methyl-2,5,7,8,-tetramethylchroman-6-ol (TMG) by mass spectrometry and nuclear magnetic resonance spectroscopy. The optimal pH of transglycosylation was 5.5, and the yield of TMG increased as the concentration of maltose increased. IMG has high solubility in water (>1×103 mg/mL). The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of TMG was found to be nearly the same as those of α-tocopherol, Trolox (2-carboxy-2,5,7,8-tetramethylchroman-6-ol), and ascorbic acid.

Helicobacter pylori Water Extract Induces Interleukin-8 Production by Gastric Epithelial Cells

In Helicobacter pylori-associated gastricmucosal injury, interleukin (IL)-8, a potent leukocytechemoattractant, is produced by epithelial cellsinfected by H. pylori and directs neutrophils to thegastric mucosa. According to previous studies, the IL-8production requires direct contact between the bacteriaand epithelial cells. The aims of the present study wereto determine whether an H. pylori water extract (HPE) induces IL-8 production by gastricepithelial cells and to characterize IL-8-inducingsubstances in HPE. Extracts were prepared from astandard strain and from strains obtained from patientswith gastric ulcers. After addition of HPE to MKN 45cells, a gastric cancer cell line, IL-8 in supernatantsand IL-8 mRNA were measured by immunoassay and reversetranscription-polymerase chain reaction, respectively. For characterization, active fractions obtainedby gel filtration of standard-strain HPE were treated byheating or trypsinization. To study the signal pathwayleading to IL-8 production, inhibitors for protein kinase A (PKA), protein kinase C (PKC),or protein tyrosine kinase (PTK) were incubated withMKN45 cells before HPE stimulation. HPE from thestandard strain and one of these clinical strainsinduced IL-8 production. Lipopolysaccharide or cagA inthe strains showed no correlation with IL-8concentration. Standard-strain HPE induced IL-8 mRNAexpression in MKN 45 cells. Gel filtration localizedactivity to a low-molecular-weight fraction of about 7kDa, which was resistant to heat and trypsin digestion.PKC inhibitors significantly blocked HPE-induced IL-8production by MKN 45 cells; however, the PKA inhibitor or PTK inhibitors showed a partial inhibitoryeffect. HPE contains a nonprotein substance of lowmolecular weight that is responsible for IL-8 inductionin gastric epithelial cells. This induction is mainly dependent on the activation of PKC butpartially also dependent on PKA or PTK.

In Vivo Postirradiation Protection by a Vitamin E Analog, α-TMG

Abstract Satyamitra, M. M., Uma Devi, P., Murase, H. and Kagiya, V. T. In Vivo Postirradiation Protection by a Vitamin E Analog, α-TMG. Radiat. Res. 160, 655–661 (2003). The water-soluble vitamin E derivative α-TMG is an excellent radical scavenger. A dose of 600 mg/kg TMG significantly reduced radiation clastogenicity in mouse bone marrow when administered after irradiation. The present study was aimed at investigating the radioprotective effect of postirradiation treatment with α-TMG against a range of whole-body lethal (8.5–12 Gy) and sublethal (1–5 Gy) doses of radiation in adult Swiss albino mice. Protection against lethal irradiation was evaluated from 30-day mouse survival and against sublethal doses was assessed from micronuclei and chromosomal aberrations in the bone marrow 24 h after irradiation. An intraperitoneal injection of 600 mg/kg TMG within 10 min of lethal irradiation increased survival, giving a dose modification factor (DMF) of 1.09. TMG at doses of 400 mg/kg and 600 mg/kg significantly reduced the percentage of aberrant metaphases, the different types of aberrations, and the number of micronucleated erythrocytes. DMFs of 1.22 and 1.48 for percentage aberrant metaphases and 1.6 and 1.98 for micronuclei were obtained for 400 mg/kg and 600 mg/kg TMG, respectively. No drug toxicity was observed at these doses. The effectiveness of TMG when administered postirradiation suggests its possible utility for protection against unplanned radiation exposures.

Effects of Phenolic Compounds on Reactions Involving Various Organic Radicals

Investigation of effects produced by 26 various phenol and diphenol derivatives, including industrial and natural antioxidants (ionol, bis-phenol 2246, α-tocopherol), on final product yields of radiation-induced free-radical processes involving peroxyl, alkyl, α-hydroxyalkyl and α,β-dihydroxyalkyl radicals has been performed. Ionol and bis-phenol 2246 have been shown to be more effective than α-tocopherol or diphenol derivatives in suppressing hydrocarbon oxidation processes. At the same time, α-tocopherol and its water-soluble analogues, as well as diphenol-based substances, are more effective than phenol derivatives in regulating various homolytic processes involving carbon-centered radicals. This fact can be accounted for by taking into consideration the contribution to formation of the final product set and the respective yields made by semiquinone radicals and compounds with quinoid structure arising in the course of homolytic transformations in systems containing diphenol derivatives.

Inhibitory effect of a novel water-soluble vitamin E derivative on atherosclerosis in rabbits

A novel vitamin E derivative that is freely soluble in water, 2-(alpha-D-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol (TMG), was evaluated for ability to inhibit development of atherosclerosis in Watanabe heritable hyperlipidemic (WHHL) rabbits or cholesterol-loaded New Zealand White rabbits. Although TMG rapidly entered the circulation blood after oral administration, the blood TMG concentration remained low, while neither TMG nor its metabolites appeared in the low-density lipoprotein (LDL) fraction. TMG did not decrease serum total cholesterol and the various lipoprotein-associated cholesterol fractions (very LDL-, or high-density lipoprotein- (HDL) cholesterol). TMG reduced the serum concentration of thiobarbituric acid-reactive substances (TBARS; an index of lipid peroxidation) in cholesterol-loaded rabbits but not WHHL rabbits. Nonetheless, TMG inhibited aortic atherosclerosis as effectively as probucol in both models. Our results indicate that TMG opposes progression of atherosclerosis not only by preventing oxidation of LDL, but also by presently unknown mechanisms. Even an antioxidant with no uptake by LDL apparently can inhibit development of atherosclerosis despite a very low serum concentration.

Modification of Mortality and Tumorigenesis by Tocopherol-mono-glucoside (TMG) Administered after X Irradiation in Mice and Rats

Abstract The effects of TMG [2-(α-d-glucopyranosyl) methyl-2,5,7,8-tetramethylchroman-6-ol], a water-soluble vitamin E derivative, administered after irradiation on the mortality of X-irradiated mice and on the development of tumors in the mammary and pituitary glands in rats were investigated. When TMG (650 mg/kg) was administered intraperitoneally (i.p.) to C3H mice immediately after whole-body exposure to 7 Gy radiation, the 30-day survival was significantly higher than that of the control mice. The i.p. administration of TMG at 4 h after irradiation significantly improved survival compared to that of the controls, but administration 8 h after irradiation did not have a significant effect. Subcutaneous administration of TMG immediately after irradiation also decreased mortality significantly. When dams of lactating Wister rats were exposed to 1.5 Gy of X rays at day 21 after parturition and were then treated with diethylstilbestrol as a tumor promoter, the incidence of mammary tumors and pituitary tumors was increased compared to that in the nonirradiated control group. The administration of TMG (600 mg/kg, i.p.) after irradiation significantly reduced the incidence of mammary tumors and pituitary tumors. The number of rats that were free of both mammary and pituitary gland tumors was enhanced fourfold by TMG. These results suggest that TMG is effective in preventing radiation-induced bone marrow death in mice and in reducing mammary and pituitary tumors in rats even when it is administered after irradiation.

A NOVEL WATER-SOLUBLE VITAMIN E DERIVATIVE PREVENTS ACUTE LUNG INJURY BY BACTERIAL ENDOTOXIN

1. Various chemokines, such as keratinocyte chemoattractant (KC), macrophage inflammatory protein (MIP)‐1α and macrophage chemoattractant protein (MCP)‐1, are involved in the pathogenesis of acute lung injury induced by bacterial endotoxin (lipopolysaccharide; LPS). Oxidative stress is an important regulator of the expression of these chemokines, whereas vitamin E protects against LPS‐induced insults. In the present study, we determined the effects of 2‐(α‐d‐glucopyranosyl) methyl‐2,5,7,8‐tetramethylchroman‐6‐ol (TMG), a novel water‐soluble vitamin E derivative with excellent anti‐oxidant activity, on acute lung injury induced by intratracheal instillation of LPS (125 µg/kg) in mice.

Analysis of the addition products of α-tocopherol with phosphatidylcholine-peroxyl radicals by high-performance liquid chromatography with chemiluminescent detection.

A chemiluminescence-based high-performance liquid chromatographic method was developed for the analysis of the addition products of α-tocopherol with phosphatidylcholine-peroxyl radicals (TOO-PC). The TOO-PC eluted from a reversed-phase column was reacted with a chemiluminescent reagent consisting of a Cypridina luciferin analog and a lipid-soluble iron chelate in acidic methanol at 50°C, and the generated chemiluminescence was monitored. The detection limit for TOO-PC by this method was about 1 pmol. This method was applied to the detection of TOO-PC in the peroxidized membranes prepared from rabbit erythrocyte ghosts. When the erythrocyte ghosts were peroxidized by the addition of a water-soluble free radical initiator, a peak corresponding to TOO-PC was detected on the chromatogram with chemiluminescent detection. The amount of TOO-PC in the erythrocyte membranes increased with the depletion of endogenous α-tocopherol. The results indicate that this method proved useful for the detection of the TOO-PC formed by the peroxyl-radical scavenging reactions of α-tocopherol in biological systems.

A Novel Vitamin E Derivative (TMG) Protects Against Gastric Mucosal Damage Induced by Ischemia and Reperfusion in Rats

The aim of the present study was to investigate the antioxidative effects of water-soluble vitamin E derivative, 2-(α-d-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol (TMG), on ischemia–reperfusion (I/R) -induced gastric mucosal injury in rats. Gastric ischemia was induced by applying a small clamp to the celiac artery and reoxygenation was produced by removal of the clamp. The area of gastric mucosal erosion, the concentration of thiobarbituric acid-reactive substances, and the myeloperoxidase activity in gastric mucosa significantly increased in I/R groups compared with those of sham-operated groups. These increases were significantly inhibited by pretreatment with TMG. The contents of both mucosal TNF-α and CINC-2β in I/R groups were also increased compared with the levels of those in sham-operated groups. These increases of the inflammatory cytokines were significantly inhibited by the treatment with TMG. It is concluded that TMG inhibited lipid peroxidation and reduced development of the gastric mucosal inflammation induced by I/R in rats.

A novel water-soluble vitamin E derivative, 2-(alpha-D-glucopyranosyl)methyl-2,5,7,8-tetramethylchroman-6-ol, protects against acute lung injury and mortality in endotoxemic rats.

Satisfactory therapy for acute lung injury related to endotoxemia remains to be established. However, in vivo antioxidant treatment with N-acetylcysteine reportedly suppresses acute lung injury and proinflammatory cytokine production induced by endotoxin (lipopolysaccharide, LPS). In addition, intrinsic vitamin E is protective against LPS-induced insults. We determined the effects of a novel water-soluble vitamin E derivative, 2-(&agr;-d-glucopyranosyl) methyl-2,5,7,8-tetramethylchroman-6-ol (TMG), on acute lung injury and mortality induced by LPS in rats. Intravenous injection of TMG (4 or 40 mg/kg) effectively decreased mortality and prevented the increased alveolar permeability and pulmonary edema that were caused by intravenous injection of LPS (20 mg/kg). Treatment with TMG decreased the enhanced lung expression of TNF-&agr; caused by LPS. TMG also suppressed the sequestration of neutrophils in the lung induced by LPS. These results indicate that TMG is a possible therapeutic agent for acute lung injury and mortality, especially that caused by gram-negative bacteria. The therapeutic effects could be mediated at least partly through suppression of the increased expression of TNF-&agr; and neutrophil sequestration in the lung that are caused by LPS.