Copper-dependent inhibition and oxidative inactivation with affinity cleavage of yeast glutathione reductase.

Effects of copper on the activity and oxidative inactivation of yeast glutathione reductase were analyzed. Glutathione reductase from yeast was inhibited by cupric ion and more potently by cuprous ion. Copper ion inhibited the enzyme noncompetitively with respect to the substrate GSSG and NADPH.

Iron-dependent oxidative inactivation with affinity cleavage of pyruvate kinase.

Treatment of rabbit muscle pyruvate kinase with iron/ascorbate caused an inactivation with the cleavage of peptide bond. The inactivation or fragmentation of the enzyme was prevented by addition of Mg2+, catalase, and mannitol, but ADP and PEP the substrates did not show any effect. Protective effect of catalase and mannitol suggests that hydroxyl radical produced through the ferrous ion-dependent reduction of oxygen is responsible for the inactivation/fragmentation of the enzyme.

Activation of NADPH oxidase 1 in tumour colon epithelial cells.

In the plasma membrane fraction from Caco-2 human colon carcinoma cells, active Nox1 (NADPH oxidase 1) endogenously co-localizes with its regulatory components p22(phox), NOXO1, NOXA1 and Rac1. NADPH-specific superoxide generating activity was reduced by 80% in the presence of either a flavoenzyme inhibitor DPI (diphenyleneiodonium) or NADP(+). The plasma membranes from PMA-stimulated cells showed an increased amount of Rac1 (19.

Oxidative inactivation of reduced NADP-generating enzymes in E. coli: iron-dependent inactivation with affinity cleavage of NADP-isocitrate dehydrogenase.

Treatment of E. coli extract with iron/ascorbate preferentially inactivated NADP-isocitrate dehydrogenase without affecting glucose-6-phosphate dehydrogenase. NADP-Isocitrate dehydrogenase required divalent metals such as Mg(2+), Mn(2+ )or Fe(2+) ion.

Prooxidant action of maltol: role of transition metals in the generation of reactive oxygen species and enhanced formation of 8-hydroxy-2'-deoxyguanosine formation in DNA.

Maltol (3-hydroxy-2-methyl-4-pyrone) produced reactive oxygen species as a complex with transition metals. Maltol/iron complex inactivated aconitase the most sensitive enzyme to oxidative stress. The inactivation of aconitase was iron-dependent, and prevented by TEMPOL, a scavenger of reactive oxygen species, suggesting that the maltol/iron-mediated generation of superoxide anion is responsible for the inactivation of aconitase.

Inhibitory action of eugenol compounds on the production of nitric oxide in RAW264.7 macrophages.

Effects of eugenol compounds on the production of nitric oxide (NO) in RAW264.7 macrophages were analyzed in relation to the anti-inflammatory action of these compounds. Eugenol and isoeugenol inhibited lipopolysaccharide (LPS)-dependent production of NO, which was due to the inhibition of protein synthesis of inducible nitric oxide synthase (iNOS).

Generation of reactive oxygen species and induction of apoptosis of HL60 cells by ingredients of traditional herbal medicine, Sho-saiko-to.

The prooxidant and apoptosis-inducing effects of Sho-saiko-to, a traditional Sino-Japanese herbal medicine and its active ingredients were analyzed. Among the components of Sho-saiko-to, wogon, the extract of Scutellaria and licorice root extract induced apoptosis of HL60 cells and increased the intracellular levels of reactive oxygen species. Lower concentrations (5 to 20 muM) of baicalein, the principal flavonoid in the Scutellaria root extract, showed induction of cell apoptosis and elevated the intracellular reactive oxygen species.

Prooxidant action of hinokitiol: hinokitiol-iron dependent generation of reactive oxygen species.

Hinokitiol (alpha-thujaplicin, 2-hydroxy-4-isopropyl-2,4,6-cycloheptatrien-1-one), one of the tropolone compounds purified from the woods of Chamaecyparis and Thujopsis (hinoki and hiba), produced reactive oxygen species as a complex with transition metals. Hinokitiol/iron complex inactivated aconitase, the most sensitive enzyme to reactive oxygen, whereas it did not affect aldolase and glyceraldehyde 3-phosphate dehydrogenase. The inactivation of aconitase was iron-dependent, and prevented by TEMPOL, a scavenger of reactive oxygen species and superoxide dismutase, suggesting that the hinokitiol/iron-mediated generation of superoxide anion is responsible for the inactivation of aconitase.

Maltol/iron-mediated apoptosis in HL60 cells: participation of reactive oxygen species.

Apoptosis of HL60 cells by maltol was analyzed in relation to the maltol/iron-mediated generation of reactive oxygen species. Addition of maltol with FeSO(4) induced an apoptotic cell death as judged by flow cytometry analysis and DNA fragmentation on electrophoresis, but maltol or iron alone did not affect the cells. Treatment of HL60 cells with maltol/iron complex caused an effective inactivation of aconitase the most sensitive enzyme to reactive oxygen species.

Rosmarinic acid inhibits the formation of reactive oxygen and nitrogen species in RAW264.7 macrophages.

Antioxidant action of Rosmarinic acid (Ros A), a natural phenolic ingredient in many Lamiaceae herbs such as Perilla frutescens, sage, basil and mint, was analyzed in relation to the Ikappa-B activation in RAW264.7 macrophages. Ros A inhibited nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) protein synthesis induced by lipopolysaccharide (LPS), and also effectively suppressed phorbol 12-myristate 13-acetate (PMA)-induced superoxide production in RAW264.

Involvement of peroxynitrite in capsaicin-induced apoptosis of C6 glioma cells.

Capsaicin induces apoptosis in some types of cells, but its mechanism remains obscure. In this study, peroxynitrite, a powerful oxidant generated from the reaction of superoxide and nitric oxide (NO) in biological system, was demonstrated to be responsible for capsaicin-mediated apoptosis in C6 glioma cells. Capsaicin-induced apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and also identified by Annexin V staining and comet assay.

Prooxidant activity of curcumin: copper-dependent formation of 8-hydroxy-2'-deoxyguanosine in DNA and induction of apoptotic cell death.

Curcumin, a well-known antioxidant in a principal ingredient of turmeric, acted as a prooxidant causing a copper-dependent DNA damage and the induction of apoptosis. Treatment of DNA from plasmid pBR322 and calf thymus with curcumin plus copper ion caused strand scission and the formation of 8-hydroxy-2(')-deoxyguanosine in DNA. Addition of catalase protected DNA from the curcumin-dependent injuries, indicating that hydroxyl radical may participate in the DNA damage.

Role of vanilloid receptors in the capsaicin-mediated induction of iNOS in PC12 cells.

The vanilloid receptor 1(VR1) is a nonselective cation channel that is activated by pungent vanilloid compound, extracellular protons, or noxious heat. mRNA of VR1 and vanilloid receptor 1-like receptor (VRL1) were expressed in PC12 cells, and only VRI mRNA was detected in glioma and A10 cell lines. VRI protein was demonstrated in PC12 cells by immunocytochemistry and Western blotting.