Glutathione Prodrugs Research Articles

Impact of N-acetylcysteine and etodolac treatment on systolic and diastolic function in a rat model of myocardial steatosis induced by high-fat-diet.

Obesity is a worldwide problem, leading to cardiomyopathy. Oxidative stress and inflammation have been reported to play significant roles in developing obesity cardiomyopathy. N-acetylcysteine is a glutathione prodrug that preserves liver against steatosis via constraining the production of reactive oxygen species. Etodolac is a nonsteroidal anti-inflammatory drug which has been demonstrated to protect liver against fibrosis. The aim of the present study was to evaluate and compare the effects of N-acetylcysteine and etodolac on impaired cardiac functions due to high-fat-diet (HFD) induced myocardial steatosis in rats. Thirty-two male Sprague-Dawley rats were randomly divided into four groups. Control group was maintained on standard-rat-basic-diet (SD) for 20 weeks, while HFD was given to three study groups for 20 weeks. Then N-acetylcysteine was given to one of the study groups (HFD+NAC), and etodolac to another group (HFD+ETD) as a supplement for 4 weeks while all groups were continued on SD. At the end of the study periods, hearts were examined by Langendorff technique and rat livers were evaluated histologically. HFD and HFD+ETD groups presented with significantly higher steatosis and fibrosis in liver compared to other groups. HFD+NAC preserved diastolic functions. Also HFD+NAC and HFD+ETD groups had significantly better systolic funtions than HFD group. Obesity is associated with diastolic dysfunction rather than systolic dysfunction. NAC may protect the heart against diastolic dysfunction due to obesity. NAC and etodolac treatment improve systolic function, even in the absence of systolic dysfunction.

Effectiveness of 4-hydroxy phenyl N-tert-butylnitrone (4-OHPBN) alone and in combination with other antioxidant drugs in the treatment of acute acoustic trauma in chinchilla

Acute acoustic trauma (AAT) results in oxidative stress to the cochlea through overproduction of cellular reactive oxygen, nitrogen, and other free radical species appearing from 1 h to 10 days after noise exposure. It has been shown that N-acetyl-L-cysteine (NAC), a glutathione prodrug, and acetyl-L-carnitine (ALCAR), a mitochondrial biogenesis agent, are effective in reducing noise-induced hearing loss. Phenyl N-tert-butylnitrone (PBN), a nitrone-based free radical trap, appears to suppress oxidative stress in a variety of disorders and several biological models. In this study, we tested whether 4-hydroxy PBN (4-OHPBN), a major metabolite of PBN, administered 4 h after noise exposure is effective in treating noise-induced hearing loss and whether a combination of antioxidant drugs (4-OHPBN plus NAC and 4-OHPBN plus NAC plus ALCAR) provides greater efficacy in attenuating AAT since each agent addresses different injury mechanisms. Chinchilla were exposed to a 105 dB octave-band noise centered at 4 kHz for 6 h. 4-OHPBN and combinations of antioxidant drugs were intraperitoneally administered beginning 4 h after noise exposure. Hearing threshold shifts in auditory brainstem responses and missing outer hair cell counts were obtained. 4-OHPBN reduced threshold shifts in a dose-dependent manner while both drug combinations showed greater effects. These results demonstrate that 4-OHPBN and combinations of antioxidants can effectively treat acute acoustic trauma and drug combinations may increase the effectiveness of treatment and decrease the required individual medication dose.

Review: Targeting therapeutics against glutathione depletion in diabetes and its complications

Glutathione (GSH) is the most abundant intracellular antioxidant, the dysregulation of which is widely implicated in disease states. There is in vitro and clinical evidence that abnormal glutathione status is involved in β-cell dysfunction and in the pathogenesis of long-term complications of diabetes. Interest has developed in the potential for therapeutic modification of glutathione status in the treatment of diabetes. There is evidence which supports the use of glutathione pro-drugs, lipoic acid and vitamin supplementation but further studies are required before these enter widespread use. Studies into the role of oxidative stress in diabetes rely heavily on the ability to measure glutathione, which has been a problematic analyte to measure in the laboratory. New electrochemical methods being developed should speed up the rate at which data can be accumulated and will help define clinical utility for its measurement.

Protective Effects of α-Tocopherol and N-Acetyl-Cysteine on Diazinon-Induced Oxidative Stress and Acetylcholinesterase Inhibition in Rats

ABSTRACTDiazinon, an organophosphate (OP) insecticide, is widely used in agriculture and domestically. Reactive oxygen species (ROS) caused by OPs are involved in the toxicity of various pesticides. The aim of the present study was to analyze the role of diazinon in inducing oxidative stress in adult male Wistar rats and to evaluate the possible protective effects of α-tocopherol (TPH) and the glutathione prodrug N-acetyl-cysteine (NAC) after 4 weeks of exposure to a sublethal dose of diazinon. TPH (10 mg/kg/day), NAC (160 mg/kg/day), diazinon (25 mg/kg/day), a combination of NAC (160 mg/kg/day) and diazinon (25 mg/kg/day), and a combination of TPH (10 mg/kg/day) and diazinon (25 mg/kg/day) were given to rats orally via gavage for 4 weeks. The thiobarbituric acid reactive substances (TBARS) marker of lipid peroxides levels, total thiol molecules, and total antioxidant capacity of plasma were all analyzed as biomarkers of oxidative stress. In addition, the acetylcholinesterase (AChE) activity was measured as a biomarker of toxicity. The results from this study well indicate diazinon-induced oxidative stress demonstrated by enhanced TBARS, decreased total thiol molecules, and total antioxidant capacity. In addition, AChE activity was inhibited as a marker of OP toxicity. Data show the protective roles of TPH and NAC in reducing the diazinon-induced oxidative stress. Interestingly, both TPH and NAC recovered diazinon-induced AChE inhibition. It is concluded that supplementation with TPH and NAC can reduce toxicity of OP in human exposure.

Prevention of naphthalene‐induced pulmonary toxicity by glutathione prodrugs: Roles for glutathione depletion in adduct formation and cell injury

Naphthalene is metabolized in the lung and liver to reactive intermediates by cytochrome P450 enzymes. These reactive species deplete glutathione, covalently bind to proteins, and cause necrosis in Clara cells of the lung. The importance of glutathione loss in naphthalene toxicity was investigated by using the glutathione prodrugs (glutathione monoethylester or cysteine-glutathione mixed disulfide) to maintain glutathione pools during naphthalene exposure. Mice given a single intraperitoneal injection of naphthalene (1.5 mmol/kg) were treated with either prodrug (2.5 mmol/kg) 30 min later. Both compounds effectively maintained glutathione levels and decreased naphthalene-protein adducts in the lung and liver. However, cysteine-glutathione mixed disulfide was more effective at preventing Clara cell injury. To study the prodrugs in Clara cells without the influence of hepatic naphthalene metabolism and circulating glutathione, dose-response and time-course studies were conducted with intrapulmonary airway explant cultures. Only the ester of glutathione raised GSH in vitro; however, both compounds limited protein adducts and cell necrosis. In vitro protection was not associated with decreased naphthalene metabolism. We conclude that (1) glutathione prodrugs can prevent naphthalene toxicity in Clara cells, (2) the prodrugs effectively prevent glutathione loss in vivo, and (3) cysteine-glutathione mixed disulfide prevents naphthalene injury in vitro without raising glutathione levels.

Novel inhibitory effects of gamma-glutamylcysteine ethyl ester against human immunodeficiency virus type 1 production and propagation.

The anti-human immunodeficiency virus type I (anti-HIV-1) effects of gamma-glutamylcysteine ethyl ester (gamma-GCE; TEI-2306) were examined in vitro. In initial studies using a vigorously HIV-1-producing human T-lymphocytic cell line, gamma-GCE displayed a novel biphasic repressive effect on chronic HIV-1 infection that was unlike that of other glutathione prodrugs or other reported antioxidants. In high doses, up to a concentration of 2.5 mM, at which neither glutathione (GSH) nor another GSH precursor has shown inhibitory effects, gamma-GCE potently inhibited the production of HIV-1 by a selective cytopathic effect against infected cells, while the viability and growth of uninfected cells were unaffected at the same gamma-GCE concentrations. At lower concentrations (200 to 400 microM), gamma-GCE significantly repressed the virus production from chronically HIV-1-expressing cells without affecting their viability. The discrepancy of the thresholds of the toxic doses between infected and uninfected cells was found to be more than 10-fold. Relatively high doses of gamma-GCE, utilized in acute HIV-1 infection of T-lymphocytic cells, entirely blocked the propagation of HIV-1 and rescued the cells from HIV-1-induced cell death. Furthermore, gamma-GCE at such concentrations was found to directly inhibit the infectivity of HIV-1 within 4 h. Repressive effects of gamma-GCE on acute HIV-1 infection in human primary human peripheral blood mononuclear cells were also demonstrated. Here, the anti-HIV-1 strategy utilizing gamma-GCE is removal of both HIV-1-producing cells and free infectious HIV-1 in vitro, in place of specific immunoclearance in vivo, which might lead to an arrest or slowing of viral propagation in HIV-1-infected individuals.

New evidence for role of glutathione in HIV infection

Glutathione may be one of the keys to a strong immune system in patients with AIDS. This finding has many clinical implications for patients, as it suggests that certain glutathione-depleting drugs should be avoided, and that the glutathione prodrug acetylcysteine may be able to boost the immune system of particular patient groups. The latest evidence supporting such a role for glutathione was presented at the Joint Meeting of the American Academy of Allergy, Asthma and Immunology, the American Association of Immunologists and the Clinical Immunology Society [ San Francisco, US; February 1997 ].