Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was designed to (1) evaluate retinal lipid peroxidation in early diabetes by the method specific for free malondialdehyde and 4-hydroxyalkenals, (2) identify impaired antioxidative defense mechanisms and (3) assess if enhanced retinal oxidative stress in diabetes is prevented by the potent antioxidant, DL-alpha-lipoic acid. The groups included control and streptozotocin-diabetic rats treated with or without DL-alpha-lipoic acid (100 mg kg(-1) day(-1), i.p., for 6 weeks). All parameters were measured in individual retinae. 4-Hydroxyalkenal concentration was increased in diabetic rats (2.63+/-0.60 vs. 1.44+/-0.30 nmol/mg soluble protein in controls, P<0.01), and this increase was prevented by DL-alpha-lipoic acid (1.20+/-0.88, P<0.01 vs. untreated diabetic group). Malondialdehyde, reduced glutathione (GSH) and oxidized glutathione (GSSG) concentrations were similar among the groups. Superoxide dismutase, glutathione peroxidase (GSHPx), glutathione reductase (GSSGRed) and glutathione transferase (GSHTrans) activities were decreased in diabetic rats vs. controls. Quinone reductase was upregulated in diabetic rats, whereas catalase and cytoplasmic NADH oxidase activities were unchanged. DL-alpha-Lipoic acid prevented changes in superoxide dismutase and quinone reductase activities induced by diabetes without affecting the enzymes of glutathione metabolism. In conclusion, accumulation of 4-hydroxyalkenals is an early marker of oxidative stress in the diabetic retina. Increased lipid peroxidation occurs in the absence of GSH depletion, and is prevented by DL-alpha-lipoic acid.
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PMID:Early changes in lipid peroxidation and antioxidative defense in diabetic rat retina: effect of DL-alpha-lipoic acid. 1085 58

alpha-Lipoic acid (LA), an antioxidant with broad neuroprotective capacity, is thought to act by scavenging reactive oxygen species and stimulation of glutathione synthesis. LA shows structural resemblance to dithiolethiones, like anethole dithiolethione (ADT). ADT protects against oxidative damage, primarily by induction of phase II detoxication enzymes, in particular NAD(P)H:quinone oxidoreductase (NQO1) and glutathione-S-transferase (GST). Therefore, we investigated whether LA, like ADT, is capable also of inducing these protective enzymes. Our data show that LA, like ADT, induces a highly significant, time- and concentration dependent, increase in the activity of NQO1 and GST in C6 astroglial cells. The LA or ADT mediated induction of NQO1 was further confirmed by quantitative PCR and western blot analysis. This work for the first time unequivocally demonstrates LA mediated upregulation of phase II detoxication enzymes, which may highly contribute to the compounds' neuroprotective potential. Moreover, the data support the notion of a common mechanism of action of LA and ADT.
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PMID:The neuroprotective antioxidant alpha-lipoic acid induces detoxication enzymes in cultured astroglial cells. 1218 Jan 95

Diabetes-induced erectile dysfunction is one of the most prevalent complications of diabetes in males. alpha-Lipoic acid (ALA) and its reduced form, dihydrolipoic acid, are powerful antioxidants. Data strongly suggest that, because of its antioxidant properties, ALA is particularly suited to the prevention and/or treatment of diabetic complications that arise from overproduction of reactive oxygen and nitrogen. The aim of this study was to investigate the localization of nitric oxide synthetase (NOS) in normal and diabetic rat cavernous smooth muscles and to examine the effects of ALA on them. Rats were divided into four groups: control, diabetic, diabetic plus ALA, and ALA only. Penile tissues were taken 15 days after drug application and examined histochemically and immunohistochemically. Comparison of the control and diabetic groups revealed that the axons of nerve cells were not identified with Masson trichrome in the diabetic group, whereas in the control group NOS localization and immunostaining (endothelial NOS [eNOS]) were normal. Diabetic rats administered ALA showed improvement in Masson trichrome, nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) and eNOS localization compared with untreated diabetic rats. Although there was no difference between the control group and the group administered ALA only, we observed an increase in NADPH-d and eNOS. In erection, eNOS and neuronal NOS (nNOS) may have a significant role. In pathologic conditions, erectile dysfunction may occur as a result of an increase in inducible macrophage-type NOS (iNOS). ALA plays an important role in treatment of erectile dysfunction by decreasing iNOS and increasing other isoforms of NOS.
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PMID:The effects of alpha-lipoic acid on nitric oxide synthetase dispersion in penile function in streptozotocin-induced diabetic rats. 1637 81

alpha-Lipoic acid (LA) is a naturally-occurring micronutrient that has been actively investigated for the treatment and management of various chronic medical conditions including neurodegenerative diseases, diabetes and hepatic disorders. However, relatively few studies have examined the effects of LA as a chemopreventive agent, particularly in regard to its ability to modulate homeostasis of oxidoreductive state and to regulate detoxification enzymes such as quinone reductase NQO1 in LA-responsive cells. We tested the hypothesis that LA affects the intracellular redox status and induces NQO1 expression using the human promyelocytic HL-60 leukemia cells. We showed that treatment by LA maintains HL-60 cells in a relatively reduced state, supported by the dose/time-dependent increase in the activities of glutathione peroxidase and glutathione reductase and decrease in the activity of catalase. Moreover, LA significantly increased the activity and protein expression of NQO1. The induction of NQO1 was accompanied by the nuclear accumulation of transcription factor Nrf2, which was correlated with a decreased level of Nrf2 in the cytosol as well as the concomitant reduction in the expression of cytoplasmic repressor of Nrf2, Keap1.
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PMID:Control of cellular redox status and upregulation of quinone reductase NQO1 via Nrf2 activation by alpha-lipoic acid in human leukemia HL-60 cells. 1881 98