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Strain of Ganoderma lucidum MDU-7 produce multiple extracellular isoforms of laccase in submerged culture condition using malt extract as a carbon source and copper sulfate as an inducer. SDS–PAGE followed by MALDI–TOF peptide fingerprinting confirmed laccase isozyme with molecular mass of 24–66 kDa. Two laccase isozymes (Glac H1 and Glac L1) were purified from native-PAGE protein purification method and a comparative catalytic and antioxidant study has been performed. Both of the laccase isozymes have optimum temperature and pH at 50 °C and 4.0, respectively. Glac L1 has higher stability in comparison to Glac H1, over wide range of temperature, pH, divalent metal ions and surfactants. The K m values of Glac L1 and Glac H1 determined for guaiacol, ABTS and O -tolidine were 98 μM, 26 μM, 320 μM and 281 μM, 29 μM, 338 μM, respectively. Glac H1, irrespective to its laccase activity and stability, acts as a better antioxidant than Glac L1. [ABSTRACT FROM AUTHOR]

Abstract: Thiol family of antioxidants has been considered to be the most effective class of radio protective agents. Present study reports a comparative evaluation of antioxidant thiols, namely N-acetyl cysteine (NAC), glutathione (GSH) and thioproline (TP), on gamma radiation-induced damage to human lymphocytes DNA as assessed by micronucleus (MN) formation and comet assay parameters. Pretreatment of cells with NAC, GSH and TP showed significant protection against DNA damage and MN frequency in irradiated lymphocytes (2–4Gy). The magnitude of DNA damage protection was found to be concentration dependent (100–300μM) which followed the order GSH>NAC>TP. Further, antioxidant thiols mediated protection against DNA damage in irradiated lymphocyte showed significant correlation with their ability to decrease intracellular ROS but not to the increase in intracellular GSH. Experiments on the effect of antioxidant thiols on plasmid DNA irradiated under cell free aqueous conditions showed that NAC exerts greater protection than GSH against radiation damage. TP showed similar responses in cellular and plasmid DNA. Greater protection of plasmid DNA by NAC is ascribable to its more potential hydrogen donor ability as revealed by radical chromogen 2,2-diphenyl-1-picrylhydrazyl (DPPH) photometric assay. Thus, present study indicated that radioprotection of lymphocytes DNA by antioxidant thiols are closely correlated to the reduction of cellular oxidative stress, which seems to involve multiple mechanisms. [Copyright &y& Elsevier]

Abstract: Cerium oxide nanoparticles (CeNPs) have shown promise as catalytic antioxidants in cell culture and animal models as both superoxide dismutase and catalase mimetics. The reactivity of the cerium (Ce) atoms at the surface of its oxide particle is critical to such therapeutic properties, yet little is known about the potential for a protein or small molecule corona to form on these materials in vivo. Moreover Ce atoms in these active sites have the potential to interact with small molecule anions, peptides, or sugars when administered in culture or animal models. Several nanomaterials have been shown to alter or aggregate under these conditions, rendering them less useful for biomedical applications. In this work we have studied the change in catalytic properties of CeNPs when exposed to various biologically relevant conditions in vitro. We have found that CeNPs are resistant to broad changes in pH and also not altered by incubation in cell culture medium. However to our surprise phosphate anions significantly altered the characteristics of these nanomaterials and shifted the catalytic behavior due to the binding of phosphate anions to cerium. Given the abundance of phosphate in biological systems in an inorganic form, it is likely that the action of CeNPs as a catalyst may be strongly influenced by the local concentration of phosphate in the cells and/or tissues in which it has been introduced. [Copyright &y& Elsevier]

Nrf2-mediated activation of antioxidant response element is a central part of molecular mechanisms governing the protective function of phase II detoxification and antioxidant enzymes against carcinogenesis, oxidative stress, and inflammation. Nrf2 is sequestered in the cytoplasm by its repressor, Keap1. We have designed and synthesized novel chalcone derivatives as Nrf2 activators. The potency of these compounds was measured by the expression of Nrf2 dependent antioxidant genes GCLM, NQO1, and HO1 in human lung epithelial cells, while the cytotoxicity was analyzed using MTT assay. In vivo potency of identified lead compounds to activate Nrf2 was evaluated using a mouse model. Our studies showed 2-trifluoromethyl-2′-methoxychalone (2b) to be a potent activator of Nrf2, both in vitro and in mice. Additional experiments showed that the activation of Nrf2 by this compound is independent of reactive oxygen species or redox changes. We have discussed a quantitative structure–activity relationship and proposed a possible mechanism of Nrf2 activation. [ABSTRACT FROM AUTHOR]