In vitro ROS- and RNS-quenching and in vivo radioprotection by TMG, a water-soluble vitamin E derivative

抄録

We have measured in vitro quenching of reactive oxygen species (ROS; superoxide anion radical and hydroxyl radical) and reactive nitrogen species (RNS; peroxynitrite) by tocophrol monoglucoside (TMG), a water-soluble vitamin E derivative, with ESR spin trapping and HPLC analysys, respectively. In vivo radioprotection by TMG was also evaluated with colony assay using L5178Y cells and 30 day survival of C3H mice after X-ray irradiation. TMG showed similar quenching activity against ROS and RNS with Trolox, another water-soluble vitamin E derivative. The quenching of superoxide radical by TMG or Trolox (IC₅₀=290 µM) was effective more than one order of magnitude than that of hydroxyl radical. In vivo radioprotection of C3H mice was observed by i.p. administration of TMG (about 650 mg/kg) either pre- or post-irradiation (whole body 7 Gy). In addition, the administration even at 30-60 min after irradiation was still effective for extending the survival.