Ubiquinone redox cycle as a cellular antioxidant defense system

Kishi, Takeo; Takahashi, Takayuki; Usui, Akinori; Okamoto, Tadashi

doi:10.1002/biof.5520100208

Cited by 18 publications

(7 citation statements)

References 30 publications

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“…The accumulation of intracellular As may interfere with the activity of the enzyme viz. cytosolic NADPH-CoQ reductase accountable for the reduction of ubiquinone to ubiquinols [38]. Simultaneous administration of AEIA along with NaAsO 2 could significantly reinstate co-enzymes Q levels in the tissues.…”

Section: Discussionmentioning

confidence: 99%

Ameliorative effect of water spinach, Ipomea aquatica (Convolvulaceae), against experimentally induced arsenic toxicity

et al. 2015

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BackgroundIpomea aquatica (Convolvulaceae) is traditionally used against Arsenic (As) poisoning in folk medicines in India. The present study was designed to explore the therapeutic role of aqueous extract of I. aquatica (AEIA) against As-intoxication.MethodsAEIA was chemically standardized by spectroscopic and chromatographic analysis. The cytoprotective role of AEIA was measured on isolated murine hepatocytes. The effect on redox status were measured after incubating the hepatocytes with NaAsO2 (10 μM) + AEIA (400 μg/ml). The protective effect of AEIA (400 μg/ml) in expressions of apoptotic proteins were estimated in vitro. The protective role of AEIA was measured by in vivo assay in mice. Haematological, biochemical, As bioaccumulation and histological parameters were evaluated to ensure the protective role of AEIA (100 mg/kg) against NaAsO2 (10 mg/kg) intoxication.ResultsPhytochemical analysis revealed presence of substantial quantities of phenolics, flavonoids, saponins and ascorbic acid in AEIA. Incubation of murine hepatocytes with AEIA (0–400 μg/ml) + NaAsO2 (10 μM) exerted a concentration dependent cytoprotective effect. Incubation of murine hepatocytes with NaAsO2 (10 μM, ~ IC50) induced apoptosis via augmenting oxidative stress. NaAsO2 treated hepatocytes exhibited significantly (p < 0.01) enhanced levels of ROS production, lipid peroxidation and protein carbonylation with concomitant depletion of antioxidant enzymes (p < 0.05-0.01) and GSH (p < 0.01) levels. However, AEIA (400 μg/ml) + NaAsO2 (10 μM) could significantly (p < 0.05-0.01) reinstate the aforementioned parameters to near-normal status. Besides, AEIA (400 μg/ml) could significantly counteract (p <0.05-0.01) ROS mediated alteration in the expressions of apoptotic proteins viz. Bcl-2, BAD, Cyt C, Apaf 1, caspases, Fas and Bid. In in vivo bioassay, NaAsO2 (10 mg/kg) treatment in mice caused significantly (p < 0.05-0.01) elevated As bioaccumulation, ATP levels, DNA fragmentations and oxidative stress in the liver, kidney, heart, brain and testes along with alteration in cytoarchitecture of these organs. In addition, the serum biochemical and haematological parameters were significantly (p < 0.05-0.01) altered in the NaAsO2-treated animals. However, concurrent administration of AEIA (100 mg/ml) could significantly reinstate the NaAsO2-induced pathogenesis.ConclusionPresence of substantial quantities of dietary antioxidants within AEIA would be responsible for overall protective effect.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0430-3) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Ameliorative effect of water spinach, Ipomea aquatica (Convolvulaceae), against experimentally induced arsenic toxicity

et al. 2015

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“…(NQO1) (7), formerly known as diaphorase, and the so far unnamed NQO1 analog with higher affinity for NADPH than NADH, which performs the same two electron redox reactions as NQO1 (24). The components of the PMET system vary by cell type; phagocytes, for instance, express specialized PMET enzymes, and NADPH oxidases, such as NOX2, and cells simultaneously express multiple enzymes capable of supporting PMET activity.…”

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confidence: 99%

Plasma membrane electron transport in pancreatic β-cells is mediated in part by NQO1

Gray

Eisen

Cline

et al. 2011

American Journal of Physiology-Endocrinology and Metabolism

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Plasma membrane electron transport (PMET), a cytosolic/plasma membrane analog of mitochondrial electron transport, is a ubiquitous system of cytosolic and plasma membrane oxidoreductases that oxidizes cytosolic NADH and NADPH and passes electrons to extracellular targets. While PMET has been shown to play an important role in a variety of cell types, no studies exist to evaluate its function in insulin-secreting cells. Here we demonstrate the presence of robust PMET activity in primary islets and clonal β-cells, as assessed by the reduction of the plasma membrane-impermeable dyes WST-1 and ferricyanide. Because the degree of metabolic function of β-cells (reflected by the level of insulin output) increases in a glucose-dependent manner between 4 and 10 mM glucose, PMET was evaluated under these conditions. PMET activity was present at 4 mM glucose and was further stimulated at 10 mM glucose. PMET activity at 10 mM glucose was inhibited by the application of the flavoprotein inhibitor diphenylene iodonium and various antioxidants. Overexpression of cytosolic NAD(P)H-quinone oxidoreductase (NQO1) increased PMET activity in the presence of 10 mM glucose while inhibition of NQO1 by its inhibitor dicoumarol abolished this activity. Mitochondrial inhibitors rotenone, antimycin A, and potassium cyanide elevated PMET activity. Regardless of glucose levels, PMET activity was greatly enhanced by the application of aminooxyacetate, an inhibitor of the malate-aspartate shuttle. We propose a model for the role of PMET as a regulator of glycolytic flux and an important component of the metabolic machinery in β-cells.

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“…Riboflavin is characterized by antihypoxic effect associated with activation of flavin reductase and reduction of the content of macroergic substances (ATP and creatine phosphate), as well as by antioxidant effects caused by glutathione reduction [8]. Nicotinamide is a component of NAD, it activates cellular NAD-dependent dehydrogenases and antioxidant systems of ubiquinone oxidoreductases, protecting cell membranes from free radicals [10]. As the targets of CN components cytoprotective effects are different in hypoxia, presumably, their effects are synergic.…”

Section: Resultsmentioning

confidence: 99%

Effect of cerebronorm on energy metabolism and lipid peroxidation in rat brain during hypoxia

Vasilyev

Хазанов

2007

Bull Exp Biol Med

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Ubiquinone redox cycle as a cellular antioxidant defense system

Cited by 18 publications

References 30 publications

Ameliorative effect of water spinach, Ipomea aquatica (Convolvulaceae), against experimentally induced arsenic toxicity

Ameliorative effect of water spinach, Ipomea aquatica (Convolvulaceae), against experimentally induced arsenic toxicity

Plasma membrane electron transport in pancreatic β-cells is mediated in part by NQO1

Effect of cerebronorm on energy metabolism and lipid peroxidation in rat brain during hypoxia

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