Prevention and Reversal of Selenite-Induced Cataracts by N-Acetylcysteine Amide in Wistar Rats

Background: The present study sought to evaluate the efficacy of N-acetylcysteine amide (NACA) eye drops in reversing the cataract formation induced by sodium selenite in male Wistar rat pups. Methods: Forty male Wistar rat pups were randomly divided into a control group, an N-acetylcysteine amide-only group, a sodium selenite-induced cataract group, and a NACA-treated sodium selenite-induced cataract group. Sodium selenite was injected intraperitoneally on postpartum day 10, whereas N-acetylcysteine amide was injected intraperitoneally on postpartum days 9, 11, and 13 in the respective groups. Cataracts were evaluated at the end of week 2 (postpartum day 14) when the rat pups opened their eyes. N-acetylcysteine amide eye drops were administered beginning on week 3 until the end of week 4 (postpartum days 15 to 30), and the rats were sacrificed at the end of week 4. Lenses were isolated and examined for oxidative stress parameters such as glutathione, lipid peroxidation, and calcium levels along with the glutathione reductase and thioltransferase enzyme activities. Casein zymography and Western blot of m-calpain were performed using the water soluble fraction of lens proteins. Results: Morphological examination of the lenses in the NACA-treated group indicated that NACA was able to reverse the cataract grade. In addition, glutathione level, thioltransferase activity, m-calpain activity, and m-calpain level (as assessed by Western blot) were all significantly higher in the NACA-treated group than in the sodium selenite-induced cataract group. Furthermore, sodium selenite- injected rat pups had significantly higher levels of malondialdehyde, glutathione reductase enzyme activity, and calcium levels, which were reduced to control levels upon treatment with NACA. Conclusions: The data suggest that NACA has the potential to significantly improve vision and decrease the burden of cataract-related loss of function. Prevention and reversal of cataract formation could have a global impact. Development of pharmacological agents like NACA may eventually prevent cataract formation in high-risk populations and may prevent progression of early-stage cataracts. This brings a paradigm shift from expensive surgical treatment of cataracts to relatively inexpensive prevention of vision loss

Antioxidant Potential of Sutherlandia Frutescens and its Protective Effects against Oxidative Stress in Various Cell Cultures

Sutherlandia frutescens (L.) R.Br. (SF) is a South African plant that is widely used to treat stress, infections, cancer, and chronic diseases, many of which involve oxidative stress. The aim of the study was to quantitatively assess the antioxidant potential of SF extracts in cell-free system as well as in cell lines. Dried SF vegetative parts were extracted using six different solvents, and the extracts were assessed for total phenolic and flavonoid contents, total reducing power, iron chelating capacity, and free radical scavenging power, including, scavenging of hydroxyl radicals, superoxide anions, nitric oxide, and hydrogen peroxide. We further investigated the freeze-dried hot water extract of SF (SFE) to assess its effect against oxidative stress induced by tert-butyl hydroperoxide (t-BHP), an organic peroxide. Three different cell lines: Chinese hamster ovary (CHO), human hepatoma (HepaRG), and human pulmonary alveolar carcinoma (A549) cells, were employed to determine cell viability, intracellular reactive oxygen species (ROS) levels, and reduced to oxidized glutathione levels (GSH/GSSG). The results indicated that: (1) SF extracts have significant antioxidant potential that is dependent upon the nature of the extraction solvent and (2) SFE protects against tBHP-induced oxidative stress in cells by scavenging ROS and preserving intracellular GSH/GSSG. Oxidative stress is implicated in a number of disorders, and due to the public\u27s concerns about synthetic antioxidants, various natural antioxidants are being explored for their therapeutic potential. Our findings support claims for S. frutescens being a promising adjunctive therapeutic for oxidative stress-related health problems

The Role of N-Acetylcysteine Amide in Defending Primary Human Retinal Pigment Epithelial Cells against Tert-Butyl Hydroperoxide-Induced Oxidative Stress

Background: Age-related macular degeneration (AMD) is a leading cause of blindness in the United States among adults age 60 and older. While oxidative stress is implicated in the pathogenesis of AMD, dietary antioxidants have been shown to delay AMD progression in clinical studies. We hypothesized that N-acetylcysteine amide (NACA), a thiol antioxidant, would protect retinal pigment epithelium and impede progression of retinal degeneration. Methods: tert-Butyl hydroperoxide (TBHP) was used to induce oxidative stress in cell cultures. The goal was to evaluate the efficacy of NACA in an in vitro model of AMD in primary human retinal pigment epithelial cells (HRPEpiC). Results: Our data indicates that TBHP generated reactive oxygen species (ROS), which reduced cell viability, depleted glutathione (GSH) levels, and compromised glutathione reductase (GR) activity. Pretreatment with NACA significantly reduced ROS generation, restored GSH levels and GR activity, and recovered transepithelial electrical resistance. Pretreatment with NACA did not decrease the number of dying cells as determined by flow cytometry analysis. However, survival was significantly improved when cells were co-exposed to NACA and TBHP after a shortened pretreatment period. Conclusion: Our data suggest that pretreatment with NACA reduces sublethal but not lethal effects of TBHP in HRPEpiC. NACA significantly improves cell survival when administered prior to and during oxidative damage similar to that observed in the development of dry AMD. These results indicate that continuation of a thiol antioxidant regimen for treatment of AMD is beneficial throughout the course of the disease, and NACA is a potent antioxidant that should be further evaluated for this purpose

N-acetyl-L-cysteine Amide Protects Retinal Pigment Epithelium Against Methamphetamine-induced Oxidative Stress

Methamphetamine (METH), a highly addictive drug used worldwide, induces oxidative stress in various animal organs. Recent animal studies indicate that methamphetamine also induces oxidative stress in the retina, which is an em- bryonic extension of the forebrain. The aim of this study, therefore, was to evaluate the pro- tecttive effects of N-acetylcysteine amide (NACA) against oxidative stress induced by METH in retinal pigment epithelium (RPE) cells. Our stud- ies showed that NACA protected against METH- induced oxidative stress in retinal pigment epithelial cells. Although METH significantly de- creased glutathione (GSH) levels and increased reactive oxygen species (ROS) and malondial- dehyde (MDA) levels, these returned to control levels with NACA treatment. Overall observa- tions indicated that NACA protected RPE cells against oxidative cell damage and death by in- hibiting lipid peroxidation, scavenging ROS, in- creasing levels of intracellular GSH, and main- taining the antioxidant enzyme activity and the integrity of the bloodretinal barrier (BRB). The effectiveness of NACA should be further evalu- ated to determine its potential for the treatment of numerous retinal diseases caused by oxidative stress

N-acetylcysteine Amide (NACA), a Novel GSH Prodrug: Its Metabolism and Implications in Health

Glutathione (γ-glutamyl-cysteinyl-glycine; GSH), the most abundant non-protein thiol, plays a pivotal role in various cellular functions. Glutathione deficiency leads to oxidative stress which is implicated in aging and in a number of pathologies, including Alzheimer\u27s disease, Parkinson\u27s disease, liver disease, cystic fibrosis, sickle cell anemia, HIV, AIDS, cancer, heart attack, stroke, and diabetes. Since GSH cannot be replenished directly due to its unfavorable biochemical and pharmacokinetic properties, a logical approach to enhancing antioxidant protection would be the use of GSH prodrugs. GSH may be increased by supplying GSH prodrugs like esters of GSH, γ-glutamyl cysteine, cysteine, cysteine esters, and N-acetylcysteine (NAC). However, large doses of these prodrugs are required due to their poor bioavailability and toxicity which limit their use as a therapeutic agent. A potential candidate that possesses far better characteristics for development as a GSH prodrug to address oxidative damage is the low molecular weight thiol antioxidant, N-acetylcysteine amide (NACA). NACA\u27s characteristics as a drug were improved over NAC by neutralizing the carboxylic group of NAC, which makes the NACA molecule more lipophilic and, therefore, enhances its ability to penetrate cellular membranes. The enhanced ability to penetrate cells allows NACA to be administered at a lower dose than NAC, giving the drug a greater therapeutic index and lowering the risk of side effects that traditionally have been associated with higher doses of NAC. NACA is an excellent source of sulfhydryl (SH) groups that can be converted by the cells into metabolites capable of stimulating glutathione synthesis. The molecule can also promote intracellular detoxification and act directly as a free radical scavenger. NACA functions as a carrier of NAC and its antioxidant and free radical scavenging abilities are equal to or better than those of NAC. Promising results with NACA have provided additional momentum for research on GSH prodrug-based approaches to treat oxidative stress-related disorders. This chapter will focus on the role of NACA in protection against oxidative damage by increasing GSH levels in numerous Oxidative Stress -related diseases

N-Acetylcysteine Amide Protects Against Methamphetamine-induced Tissue Damage in CD-1 Mice

Methamphetamine (METH), a highly addictive drug used worldwide, induces oxidative stress in various animal organs, especially the brain. This study evaluated oxidative damage caused by METH to tissues in CD-1 mice and identified a therapeutic drug that could protect against METH-induced toxicity. Male CD-1 mice were pretreated with a novel thiol antioxidant, N-acetylcysteine amide (NACA, 250 mg/kg body weight) or saline. Following this, METH (10 mg/kg body weight) or saline intraperitoneal injections were administered every 2 h over an 8-h period. Animals were killed 24 h after the last exposure. NACA-treated animals exposed to METH experienced significantly lower oxidative stress in their kidneys, livers, and brains than the untreated group, as indicated by their levels of glutathione, malondialdehyde, and protein carbonyl and their catalase and glutathione peroxidase activity. This suggests that METH induces oxidative stress in various organs and that a combination of NACA as a neuro- or tissue-protective agent, in conjunction with current treatment, might effectively treat METH abusers