ubiquinone and diphenyleneiodonium

Antroquinonol have significantly anti-tumour effects on various cancer cells. There is still lack of reports on regulation of environmental factors on antroquinonol production by Antrodia camphorata.. An effective submerged fermentation method was employed to induce antroquinonol with adding H. The results demonstrated that addition of H

Topics: Antineoplastic Agents; Antrodia; Bioreactors; China; Enzyme Inhibitors; Fermentation; Hydrogen Peroxide; Molecular Structure; Mycelium; Mycology; Onium Compounds; Osmolar Concentration; Oxidants; Oxidative Stress; Reactive Oxygen Species; Stereoisomerism; Time Factors; Ubiquinone

Mitochondrial gene knockout (rho(0)) cells that depend on glycolysis for their energy requirements show an increased ability to reduce cell-impermeable tetrazolium dyes by electron transport across the plasma membrane. In this report, we show for the first time, that oxygen functions as a terminal electron acceptor for trans-plasma membrane electron transport (tPMET) in HL60rho(0) cells, and that this cell surface oxygen consumption is associated with oxygen-dependent cell growth in the absence of mitochondrial electron transport function. Non-mitochondrial oxygen consumption by HL60rho(0) cells was extensively inhibited by extracellular NADH and NADPH, but not by NAD(+), localizing this process at the cell surface. Mitochondrial electron transport inhibitors and the uncoupler, FCCP, did not affect oxygen consumption by HL60rho(0) cells. Inhibitors of glucose uptake and glycolysis, the ubiquinone redox cycle inhibitors, capsaicin and resiniferatoxin, the flavin centre inhibitor, diphenyleneiodonium, and the NQO1 inhibitor, dicoumarol, all inhibited oxygen consumption by HL60rho(0) cells. Similarities in inhibition profiles between non-mitochondrial oxygen consumption and reduction of the cell-impermeable tetrazolium dye, WST-1, suggest that both systems may share a common tPMET pathway. This is supported by the finding that terminal electron acceptors from both pathways compete for electrons from intracellular NADH.

Topics: Aerobiosis; Capsaicin; Cell Membrane; Cell Survival; Dicumarol; Diterpenes; Electron Transport; Flavins; HL-60 Cells; Humans; Mitochondria; NAD; NADP; Onium Compounds; Oxidation-Reduction; Oxygen Consumption; Tetrazolium Salts; Time Factors; Ubiquinone; Uncoupling Agents

Reactive oxygen species (ROS) mediate volatile anesthetic preconditioning. We tested the hypothesis that isoflurane (ISO) generates ROS from electron transport chain complexes I and III. Rabbits (n = 55) underwent 30 min coronary artery occlusion followed by 3 h reperfusion and received 0.9% saline, the complex I inhibitor diphenyleneiodonium (DPI; 1.5 mg/kg bolus followed by 1.5 mg/kg over 1 h), or the complex III inhibitor myxothiazol (MYX; 0.1 mg/kg bolus followed by 0.3 mg/kg over 1 h) in the absence and presence of 1.0 minimum alveolar concentration ISO. ISO was administered for 30 min and discontinued 15 min before coronary occlusion. Infarct size and ROS production (n = 32) were determined using triphenyltetrazolium staining and ethidium-DNA fluorescence, respectively. Adenosine triphosphate (ATP) synthesis in mitochondria obtained from rabbit hearts (n = 24) subjected to drug interventions was measured by luciferin-luciferase luminometry. ISO significantly (P < 0.05) reduced infarct size (19% +/- 4%) as compared with control (39% +/- 4%). MYX (35% +/- 4%), but not DPI (24% +/- 2%), abolished this protection. ISO increased ethidium-DNA fluorescence (83 +/- 11 U) as compared with control (40 +/- 12 U). MYX (35 +/- 3 U), but not DPI (78 +/- 9 U), abolished ROS generation. DPI and MYX selectively reduced complex I- and complex III-mediated ATP synthesis, respectively. ROS generated from electron transport chain complex III mediate ISO-induced cardioprotection.

Topics: Adenosine Triphosphate; Anesthetics, Inhalation; Animals; Coenzymes; Electron Transport; Enzyme Inhibitors; Hemodynamics; In Vitro Techniques; Ischemic Preconditioning, Myocardial; Isoflurane; Male; Methacrylates; Mitochondria, Heart; Myocardial Infarction; NADH Dehydrogenase; Onium Compounds; Rabbits; Reactive Oxygen Species; Thiazoles; Ubiquinone; Ventricular Function, Left

Trans-plasma membrane electron transport is critical for maintaining cellular redox balance and viability, yet few, if any, investigations have studied it in intact primary neurons. In this investigation, extracellular reduction of 2,6-dichloroindophenol (DCIP) and ferricyanide (FeCN) were measured as indicators of trans-plasma membrane electron transport by chick forebrain neurons. Neurons readily reduced DCIP, but not FeCN unless CoQ(1), an exogenous ubiquinone analog, was added to the assays. CoQ(1) stimulated FeCN reduction in a dose-dependent manner but had no effect on DCIP reduction. Reduction of both substrates was totally inhibited by epsilon-maleimidocaproic acid (MCA), a membrane-impermeant thiol reagent, and slightly inhibited by superoxide dismutase. Diphenylene iodonium, a flavoenzyme inhibitor, completely inhibited FeCN reduction but had no affect on DCIP reduction, suggesting that these substrates are reduced by distinct redox pathways. The relationship between plasma membrane electron transport and neuronal viability was tested using the inhibitors MCA and capsaicin. MCA caused a dose-dependent decline in neuronal viability that closely paralleled its inhibition of both reductase activities. Similarly capsaicin, a NADH oxidase inhibitor, induced a rapid decline in neuronal viability. These results suggest that trans-plasma membrane electron transport helps maintain a stable redox environment required for neuronal viability.

Topics: 2,6-Dichloroindophenol; Animals; Capsaicin; Catalytic Domain; Cell Membrane; Cell Survival; Cells, Cultured; Central Nervous System; Chick Embryo; Dicumarol; Dose-Response Relationship, Drug; Electron Transport; Enzyme Inhibitors; Extracellular Space; Ferricyanides; Multienzyme Complexes; NADH, NADPH Oxidoreductases; Neurons; Onium Compounds; Oxidation-Reduction; Rotenone; Sulfhydryl Reagents; Superoxide Dismutase; Ubiquinone; Uncoupling Agents