N-acetyl-L-cysteine Concentrations Research Articles

Cerebral venous congestion alters brain metabolite profiles, impairing cognitive function

Vascular cognitive impairment (VCI) represents the second most common cause of dementia after Alzheimer's disease, and pathological changes in cerebral vascular structure and function are pivotal causes of VCI. Cognitive impairment caused by arterial ischemia has been extensively studied the whole time; the influence of cerebral venous congestion on cognitive impairment draws doctors’ attention in recent clinical practice, but the underlying neuropathophysiological alterations are not completely understood. This study elucidated the specific pathogenetic role of cerebral venous congestion in cognitive-behavioral deterioration and possible electrophysiological mechanisms. Using cerebral venous congestion rat models, we found these rats exhibited decreased long-term potentiation (LTP) in the hippocampal dentate gyrus and impaired spatial learning and memory. Based on untargeted metabolomics, N-acetyl-L-cysteine (NAC) deficiency was detected in cerebral venous congestion rats; supplementation with NAC appeared to ameliorate synaptic deficits, rescue impaired LTP, and mitigate cognitive impairment. In a cohort of cerebral venous congestion patients, NAC levels were decreased; NAC concentration was negatively correlated with subjective cognitive decline (SCD) score but positively correlated with mini-mental state examination (MMSE) score. These findings provide a new perspective on cognitive impairment and support further exploration of NAC as a therapeutic target for the prevention and treatment of VCI.

Influence of dose and exposition time in the effectiveness of N-Acetyl-l-cysteine treatment in A549 human epithelial cells

N-Acetyl-l-cysteine (NAC) acts as a precursor of the tripeptide glutathione (GSH), one of the principal cell mechanisms for reactive oxygen species (ROS) detoxification. Chronic obstructive pulmonary disease (COPD) is associated with enhanced inflammatory response and oxidative stress and NAC has been used to suppress various pathogenic processes in this disease. Studies show that the effects of NAC are dose-dependent, and it appears that the efficient doses in vitro are usually higher than the achieved in vivo plasma concentrations. However, to date, the inconsistencies between the in vitro NAC antioxidant and anti-inflammatory in vitro effects, by reproducing the in vivo NAC plasma concentrations as well as high NAC concentrations. To do so, A549 were transfected with polyinosinic-polycytidylic acid (Poly (I:C)) and treated with NAC at different treatment periods. Oxidative stress, release of proinflammatory mediators and NFkB activation were analyzed. Results suggest that NAC at low doses in chronic administration has sustained antioxidant and anti-inflammatory effects, while acute treatment with high dose NAC exerts a strong antioxidant and anti-inflammatory response.

Germination and regeneration of Eugenia involucrata (Myrtaceae) seeds correlated with reactive oxygen species

Abstract: Seeds of the genus Eugenia L. (Myrtaceae) have interesting propagation strategies, and the reactive oxygen species (ROS) seem to be related to their germination and seedling production. In this study, the effects of ROS on the germination of E. involucrata seeds were analyzed indirectly, with the application of N-acetyl-L-cysteine (NAC), an antioxidant. The results demonstrated that the incubation in NAC suppressed and/or delayed the germination of the seeds, as well as the regeneration of roots and aerial parts. The higher the concentration of NAC, the greater the effects on seed germination and regeneration.

Design, synthesis, and biological evaluation of selenium-containing small molecule compounds based on the dual mechanism of fungal CYP51 inhibition and fungal ROS generation

Herein, we modified our previously published miconazole analogue containing selenium A03 of fungal CYP51 (belongs to the cytochrome P450 monooxygenase (CYP) superfamily) inhibitors to obtain novel analogues with inhibitory effects on multiple fungal pathogens, but also with a novel mechanism of action such as inducing fungal ROS (reactive oxygen species) generation. Firstly, three novel series of selenium-containing azole derivatives were prepared to determine their antifungal activity against common test fungal strains and fluconazole-resistant strains. Among all the novel derivatives, compounds B06, B11 and B14 with excellent antifungal activity (0.03-4 µg/mL) can inhibit the fluconazole-resistant Candida Strain 17#, CaR, 632, 901 and 904 in the range of MIC (minimal inhibitory concentrations) values (0.25–16 µg/mL). Antifungal mechanism studies revealed representative compounds not only had dose-dependent inhibitory activity of CYP51 but also down-regulated the expression of resistance-associated genes. Interestingly, representative compound B11 could also promote the generation of ROS. Therefore, the MIC values of Candida albicans (SC5314) inhibited by B11 and C06 in the presence of different concentrations of antioxidant NAC (N-acetyl-L-cysteine) were measured to further verify the synergistic antifungal effect between the mechanism promoting fungal ROS production and CYP51 inhibitory activity. Meanwhile, the results of cytotoxic evaluation showed that representative compounds were at the same level as that of miconazole with IC50 of 8.61∼29.91 µM, suggesting that the toxicity of the target compounds did not increase after the introduction of selenium atoms. Moreover, the in vitro stability assays also indicated our developed compounds possessed better liver microsomal metabolic stabilities (T1/2=14.9–20.1 min) compared with miconazole (T1/2=8.3 min). And representative compound B11 also displayed stability in rat plasma (T1/2>360 min). In addition, the docking results showed that the binding modes of target compounds B06, B11 and C06 to Candida albicans CYP51 were almost the same as those of miconazole. Overall, the selenium-containing small molecule compounds with dual mechanism can be further developed for the potential treatment of invasive fungal infections.

Metal ion‐mediated carbon dot nanoprobe for fluorescent turn‐on sensing of N‐acetyl‐l‐cysteine

In this work, carbon dots (CDs) was easily synthesized from aspartic acid through a pyrolysis method. Based on their favourable fluorescence properties, CDs were utilized to design a metal ion-mediated fluorescent probe for N-acetyl-l-cysteine (NAC) detection. The fluorescence intensity of CDs was firstly quenched by manganese ions (Mn2+ ) through static quenching effect and subsequently restored by NAC via the combination with Mn2+ due to the coordination effect. Therefore, the fluorescent turn-on sensing of NAC was actuated based on the fluorescence quenching stimulated by Mn2+ and recovery induced by coordination. The fluorescence recovery efficiencies showed a proportional range to the concentration of NAC in the range 0.04-5mmol L-1 and the detection limit was 0.03 mmol L-1 . Furthermore, this metal ion-mediated fluorescent nanoprobe was applied to human urine sample detection and the standard recovery rates were located in the range 97.62-102.34%. This was the first time that Mn2+ was used to construct a fluorescent nanoprobe for NAC. Compared with other heavy metal ions, Mn2+ with good biosecurity prevented the risk of application, which made the nanoprobe green and biopractical. The facile synthesis of CDs and novel metal ion-mediated sensing mode made it a promising method for pharmaceutical analysis.

Conductive 2D phthalocyanine-based metal-organic framework as a photoelectrochemical sensor for N-acetyl-L-cysteine detection

The thiol compound N-acetyl-L-cysteine (NAC) functions as an antioxidant in protecting cells from cytotoxic poisoning and has numerous therapeutic applications. Therefore, its quantification holds significance in clinical research. Photoelectrochemical analysis is a fast, low-cost, and efficient technique for such a purpose. However, it is challenging to use it directly for NAC detection. Therefore, in this study, conductive 2D octa-hydroxy-substituted nickel(II) phthalocyanine copper metal-organic framework (NiPc-Cu MOF) as a photoelectrochemical (PEC) sensor was successfully fabricated for enhanced room-temperature NAC determination. As NAC is able to interact with Cu compounds, the NiPc-Cu MOF was used as a PEC sensor for sensitive NAC identification. The photocurrent produced by NiPc-Cu MOF was attenuated after NAC interaction. Under optimal conditions, the sensor accurately monitored NAC concentrations ranging from 0.0125 to 42.5 μM with an ultra-low limit of detection (5.2 nM). Notably, the methodology provides a straightforward and powerful way to efficiently determine NAC in a highly selective manner, which could be significantly beneficial in pharmaceutical process monitoring and quality control.

Structural and optical properties of N-acetyl-l-cysteine capped Sb2S3 quantum dots for LED applications

Present study deals with the synthesis of N-Acetyl l-cysteine (NAC) capped Sb2S3 quantum dots via hydrothermal route. Structural properties of the synthesized material were investigated by X-ray diffraction (XRD) crystallography, photoluminescence (PL), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, and scanning electron microscopy. XRD spectra revealed the orthorhombic structure of the as-prepared samples and assisted in the calculation of crystallite size of deposited films. The most intensive peaks for prepared samples were observed at angles 16.300, 25.150, 33.440 and 36.100 indexed as (020), (310), (211) and (231), indicating successful synthesis of Sb2S3nanoparticles. Different molar concentrations of N-acetyl-l-cysteine (NAC) were employed as capping agent and it was observed that its addition resulted in decrease in noise together with decline in peak broadness as well asits shifting toward higher angles at higher concentration, thus showing better crystallinity of Sb2S3. Fourier transform infrared spectroscopy (FTIR) was used to identify the chemical bond vibrations of the different groups present in Sb2S3nanoparticles. UV–Vis spectroscopy and photoluminescence analysis were carried out to observe the optical tuneability of the as prepared samples in correspondence of its bandgap. In case of UV–Vis, the absorption spectra demonstrated a sharp fall in absorbance spectrum near the band edge indicating that the material has a direct bandgap. It was found that the value of band gap energy changed from 2.57 to 1.97 eV for different concentration of NAC. However in case of PL, the strong emission peak shift was common for all samples between 647 nm and 712 nm that reflected the slight red shift in the prepared thin films.

Ovarian tissue cryopreservation for patients with premature ovary insufficiency caused by cancer treatment: optimal protocol

Objective: Premature ovary insufficiency is frequent after chemotherapy/radiotherapy in cancer patients. Ovarian tissue (OT) cryopreservation and later retransplantation, the routine method in Europe, has recently been implemented at the first center in China. We investigated the protective effect of the antioxidant N-acetyl-l-cysteine (NAC) during the decisive freezing–thawing steps.Methods: Fifteen OT samples were obtained from each of 13 cancer patients prospectively and randomly assigned to a control group and four groups with different NAC concentrations (Group 1, 0 mM NAC; Group 2, 0.5 mM NAC; Group 3, 1 mM NAC; Group 4, 5 mM NAC; Group 5, 25 mM NAC). After thawing, the follicle viability, DNA fragmentation, levels of reactive oxygen species (ROS), and total antioxidant capacity (TAC) were evaluated.Results: OT cryopreserved and thawed with 25 mM NAC (Group 5) has the lowest proportion of apoptotic stroma cells, but the worst follicle viability. The other four groups show similar anti-apoptosis and good follicle viability. Group 4 presented the lowest ROS and highest TAC levels.Conclusions: OT cryopreserved and thawed in medium supplemented with 5 mM NAC shows the highest antioxidant and lowest ROS capability, good apoptotic parameters, and follicle viability. Our results need to be confirmed in larger patient cohorts prior to being accepted as a standard protocol.

Asperyellone prevents HDF cells from UVB irradiation damages: An elaborated study.

The current study explores the photo-protective effect of asperyellone (AY) (a fungal secondary metabolite), assessed under in vitro condition using human dermal fibroblast cell line. AY was isolated from Aspergillus sp. during the resting phase and purified. The initial cytocompatibility assessment on concentrations of AY and the duration of exposure of UVB irradiations were studied respectively. N-acetyl-L-cysteine (NAC) was used as positive control. Cells were then pretreated with optimized concentration of AY (2.0 μM) and NAC (1 mM) for 1 hour and then UVB irradiated (30 mJ/cm 2 ) for the period of 10 minutes. Results revealed that reactive oxygen species generated upon UVB irradiation found scavenged by the AY pretreatment at a significant level. Furthermore, an appreciable reduction in apoptotic cell count and DNA damages support the scavenging effect of AY. Assessments on the expression of enzymatic and nonenzymatic antioxidants evidently prove the protective role of AY. The reduced expression levels of inflammatory markers (TNF-α and COX-2), collagen degraders (MMP 2 and MMP 9), apoptotic protein expressions (Bax and Bcl-2), and cell-cycle arrest analyses substantiate the photo-protective effect of AY similar to NAC (positive control). Thus, the observations made in the current study indicate the possible role of AY as a photo-protective agent.

Determination of dissolved and particulate thiols in Lake Biwa water and extracted fulvic acids by solid phase extraction followed by HPLC with fluorescence detection

Thiols are important antioxidants that can modulate the bioavailability and biogeochemistry of many soft metals, although their detection remains challenging in both their reduced (R–S) and oxidized (R–S–S–R) forms. Here, a modified biochemical method was applied to determine the levels of dissolved and particulate thiols in Lake Biwa water and extracted Lake Biwa fulvic acids obtained at various depths. This method involves the use of the reducing agent tris(2-carboxyethyl)phosphine and the fluorescent label 7-fluorobenzofurazan-4-sulfonic acid ammonium salt (SBD-F), followed by solid-phase extraction and HPLC with fluorescence detection. Dissolved cysteine (Cys) (2.0–6.0 nM), glutathione (GSH) (2.8–5.1 nM), and N-acetyl-l-cysteine (NAC) (1.6–4.2 nM) were detected throughout the water column but were broadly consistent at depths of 5–20 m. In contrast, abundant levels of particulate cysteine (1.3–3.5 × 102 nM) and glutathione (1.6–3.1 × 102 nM) were detected down to depths of 15 m. The particulate cysteine and glutathione were significantly covariant, and the ratios between them reflected the differences in the plankton community composition and availability of these compounds. This work also studied the concentrations of Cys, GSH and NAC in Lake Biwa fulvic acids (LBFAs) for the first time (at 0 m: cysteine, 0.8 nM; glutathione, 1.6 nM; NAC, 2.5 nM; at 10 m: cysteine, 1.4 nM; glutathione, 0.6 nM; NAC, 1.6 nM). The nanomolar to sub-nanomolar concentrations of the particulate and dissolved Cys, GSH and NAC in the lake indicates that these are an important class of ligands for chalcophile metals and may influence the distribution of plankton communities from the epilimnion to the hypolimnion of the lake.

Antioxidant activity and leukemia initiation prevention in vitro and in vivo by N-acetyl-L-cysteine.

N-acetyl-L-cysteine (NAC) is the most abundant water-soluble component of garlic. No study to date has studied the leukemia prevention ability of NAC in mouse systemic leukemia model. The current study aimed to investigate the leukemia initiation prevention potential of NAC in a mouse model. The cytotoxic concentration of NAC was determined first in HL-60 cells, and its in vivo activity was studied in a mouse acute myelocytic leukemia model with WEHI-3 leukemia cells. The results showed that a non-toxic concentration of NAC efficiently scavenged free-radicals, lowered lipid peroxidation and reduced DNA damage induced by hydrogen peroxide in a cultured HL-60 leukemia cell line. NAC also elevated the cellular antioxidant enzyme activity significantly. Furthermore, NAC prevented mouse death induced by injection of murine WEHI-3 leukemia cells and reduced organ damage, as well as activated antioxidant mechanisms. The results of this study provided strong evidence that NAC may have potential benefits in terms of elevating antioxidant activity and preventing leukemia initiation.

N-acetyl-L-cysteine protects dental tissue stem cells against oxidative stress in vitro.

The aim of our study was to investigate whether N-acetyl-L-cysteine (NAC) could protect stem cells from exfoliated deciduous teeth (SHED) against oxidative damage, during in vitro cultivation, to preserve regenerative potential of these cells. Accordingly, we examined the potential of cell culture supplementation with NAC in prevention of lipid peroxidation, unfavorable changes of total lipids fatty acid composition, and the effects on the activity of antioxidant enzymes. We analyzed the extent of oxidative damage in SHED after 48h treatment with different NAC concentrations. Cellular lipid peroxidation was determined upon reaction with thiobarbituric acid. All enzyme activities were measured spectrophotometrically, based on published methods. Fatty acid methyl esters were analyzed by gas-liquid chromatography. Concentration of 0.1mM NAC showed the most profound effects on SHED, significantly decreasing levels of lipid peroxidation in comparison to control. This dose also diminished the activities of antioxidant enzymes. Furthermore, NAC treatment significantly changed fatty acid composition of cells, reducing levels of oleic acid and monounsaturated fatty acids and increasing linoleic acid, n-6, and total polyunsaturated fatty acid (PUFA) proportions. Low dose of NAC significantly decreased lipid peroxidation and altered fatty acid composition towards increasing PUFA. The reduced oxidative damage of cellular lipids could be strongly related to improved SHED survival in vitro. Low doses of antioxidants, applied during stem cells culturing and maintenance, could improve cellular characteristics in vitro. This is prerequisite for successful use of stem cells in various clinical applications.

N-acetyl-l-cysteine controls osteoclastogenesis through regulating Th17 differentiation and RANKL in rheumatoid arthritis

Background/AimsThis study aimed to determine the regulatory role of N-acetyl-l-cysteine (NAC), an antioxidant, in interleukin 17 (IL-17)-induced osteoclast differentiation in rheumatoid arthritis (RA).MethodsAfter RA synovial fibroblasts were stimulated by IL-17, the expression and production of receptor activator of nuclear factor κ-B ligand (RANKL) was determined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). Osteoclastogenesis was also determined after co-cultures of IL-17-stimulated RA synovial fibroblasts, Th17 cells and various concentrations of NAC with monocytes. After human peripheral CD4+ T cells were cultured with NAC under Th17 condition, IL-17, interferon γ, IL-4, Foxp3, RANKL, and IL-2 expression and production was determined by flow cytometry or ELISA.ResultsWhen RA synovial fibroblasts were stimulated by IL-17, IL-17 stimulated the production of RANKL, and NAC reduced the IL-17-induced RANKL production in a dose-dependent manner. NAC decreased IL-17-activated phosphorylation of mammalian target of rapamycin, c-Jun N-terminal kinase, and inhibitor of κB. When human peripheral blood CD14+ monocytes were cultured with macrophage colony-stimulating factor and IL-17 or RANKL, osteoclasts were differentiated, and NAC reduced the osteoclastogenesis. After human peripheral CD4+ T cells were co-cultured with IL-17-pretreated RA synovial fibroblasts or Th17 cells, NAC reduced their osteoclastogenesis. Under Th17 polarizing condition, NAC decreased Th17 cell differentiation and IL-17 and RANKL production.ConclusionsNAC inhibits the IL-17-induced RANKL production in RA synovial fibroblasts and IL-17-induced osteoclast differentiation. NAC also reduced Th17 polarization. NAC could be a supplementary therapeutic option for inflammatory and bony destructive processes in RA.

Polycaprolactone–Polyaniline Blend: Effects of the Addition of Cysteine on the Structural and Molecular Properties

Organic molecule conjugates usually arrange themselves into complex multiphase systems that are sensitive to processing and local chemical environment. Moreover, these conjugates are able to self-assemble at different scales, varying from nano- to macroscale. In addition, intermolecular interactions introduce structural variations in the molecular packing and large-scale ordering, which directly affects different physicochemical properties of the materials. Herein, we study the synthesis of polymer blends based on poly(e)-caprolactone (PCL) with polyaniline (PANI) doped with the amino acid N-acetyl-l-cysteine (NAC). Samples were prepared either through solution casting or via electrospinning methods. The materials were characterized regarding their morphological, structural, and molecular properties at different length scales. From the results obtained, the relationship between changes in blend properties and different NAC concentrations was determined. Deep structural details have been unveiled by using ...

N-Acetyl-l-cysteine enhances ex-vivo amplification of deciduous teeth dental pulp stem cells

ObjectiveObtaining high number of stem cells is of interest for cell based therapies. N-Acetyl-l-cysteine (NAC) acts as a source of sulfhydryl groups and an anti-oxidative agent. The aim of this study was to test different NAC concentration on proliferation and differentiation of deciduous teeth dental pulp stem cells (DTSCs) in vitro as well as to define the possible underlining mechanism of its effect. DesignNumber of viable, apoptotic and senescent DTSCs was determined after addition of NAC (0.1mM, 1.0mM, 2.0mM). Also, cell cycle analysis, HIF1-α expression, LDH isoenzymes, superoxide-dismutase (SOD) and catalase (CAT) activity, sulfhydryl groups content, the level of lipids’ and proteins’ oxidative damage and differentiation capacity of NAC treated DTSCs was determined. ResultsDTSCs expressed HIF-1α in all conditions. The lowest NAC dose (0.1mM) increased the number of DTSCs by one fifth comparing to the control, most likely stimulating entry of cells into S phase of cell cycle and enhancing the activity of LDH5 isoenzyme. The highest NAC dose (2mM) inhibited DTSCs proliferation. Also, DTSCs had the lowest level of oxidative damage with 0.1mM NAC. All tested NAC concentrations enhanced DTSCs osteo-chondrogenesis. ConclusionThe lowest NAC dose exerted significant positive effect on DTSCs proliferation as well as antioxidative protection creating beneficial environment for stem cells in vitro cultivation especially when their clinical use is important for stimulation of osteo-chondrogenesis.

Seminal Plasma: Effect on Motility, Membrane Functionality, and Spermatic Chromatin Dispersion of Equine Sperm Treated with N-acetyl-L-cysteine at 5°C

Background: N-acetyl-L-cysteine (NAC) is a low molecular weight thiol studied as an antioxidant for stallion semen preservation without changes on sperm viability. Equine seminal plasma is rich in sulfur proteins (cysteine residues) named CRISPS, which, when combined with sulfur-containing antioxidants, can enhance the appearance of DNA lesions. The aim of this study was to assess and compare the effect of different concentrations of NAC by evaluating motility, membrane function and sperm chromatin integrity of equine semen cooled at 5°C in 50% of seminal plasma.Materials, Methods & Results: Nine ejaculates from 9 stallions were divided into 4 aliquots, diluted and divided in nonsupplemented skim milk group (0.0 mM), or supplemented with 5.0, 2.5 and 0.5 mM NAC. Evaluations were made at 0 h, 24 h and 48 h of cooling, except for motility which was evaluated only up to 24 h. The 0.5 (59.7 μM2) and 5.0 mM NAC (55.5 μM2) groups showed similar areas of sperm chromatin dispersion among all groups. However, the area of chromatin dispersion between the non-supplemented group was higher = 65.3 μM2 than the group supplemented with 2.5 mM. The percentage of cells with a functional plasma membrane was similar between supplemented and non-supplemented (0.0 mM) groups, but higher (P < 0.05) in the 0.5 mM NAC (39.7 and 39.8%, respectively) than that of 2.5 mM (34.5%) and 5.0 mM (34.2%) concentrations. Progressive motility was similar among all groups supplemented with NAC. The 0.5 mM NAC group showed 35.2% motile cells while the non-supplemented group exhibited 36.2%. Although 50% seminal plasma was used, NAC did not affect sperm chromatin integrity.Discussion: Seminal plasma interfered more in the results of different concentrations of NAC. This statement is proven by the motility analysis where all NAC concentrations showed similar results. Plasma percentage higher than 20% in diluted semen causes deleterious effects on sperm, such as decreased motility and fertilizing capacity. The membrane analysis in our study was compromised because NAC (2.5 to 5.0 mM) showed high osmolarity. As this was not adjusted, it affected the result. The 2.5 mM NAC group showed a lower area of sperm chromatin dispersion than none-treated sperm, although showing similar results to the other treatments. In a study with semen of Mangalarga Marchador stallions, the 2.5 mM of NAC was able to protect sperm membrane integrity. However, in another study, where semen was kept cooled between 5 and 15°C, no change was observed on sperm quality over different concentrations of NAC. This reinforces that 2.5 mM of NAC provides adequate protection to semen exposed to harmful conditions.The high percentage of plasma associated with this sulfur antioxidant did not compromise DNA integrity, as NAC concentration used was 100 times less than the concentration needed to induce DNA lesions.

A Voltammetric Sensor Based on Modified Multi-Walled Carbon Nanotubes for N-Acetyl-L-Cysteine Determination in the Presence of Tryptophan Using 4-Chlorocatechol as a Homogenous Electrochemical Catalyst.

Simultaneous determination of N-acetyl-L-cysteine (NAC) and Tryptophan (Trp) has been studied at the surface of glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) in the presence of 4-chlorocatechol as homogenous electrochemical catalyst in aqueous media. The electrocatalytic properties of GCE modified with MWCNTs in the presence of 4-chlorocatechol toward the electrocatalytic oxidation of NAC and Trp was studied using cyclic voltammetry (CV), double-step potential chronoamperometry and differential pulse voltammetry (DPV). The results has shown that NAC participates in Michael type addition reaction with electrogenerated quinone from electrooxidation of 4-chlorocatechol at MWCNT/GCE to form the corresponding thioquinone derivative. The reoxidation of the adduct leads to increase in the oxidative current which is proportional to the concentration of NAC. Differential pulse voltammogram peak currents of NAC and Trp increased linearly with their concentration at the ranges of 5-60 μM and 5-50 μM, respectively and the detection limits for NAC and Trp were sequentially 3.427 μM and 2.494 μM. The proposed method was successfully used for the determination of NAC in pharmaceutical samples and the obtained results were found to be reasonable.

Electrocatalytic oxidation and sensitive determination of N-acetyl-L-cysteine at cyclodextrin-carbon nanotubes modified glassy carbon electrode

The electrochemical behavior and electroanalysis of N-acetyl-L-cysteine (NAC) were studied at a glassy carbon electrode modified with β-cyclodextrin (β-CD) and carbon nanotubes (β-CD/MWCNT/GCE). The β-CD/MWCNT/GCE displayed excellent electrocatalytic performance to the catalytic oxidation reactions of NAC. Because NAC is selectively enriched by β-CD, the β-CD/MWCNT/GCE can solve the problems of the signal attenuation caused by the adsorption of the NAC oxidation product. The influence of the experimental conditions on the NAC electrochemical behavior was also considered, when using a modified electrode. The mechanism and kinetics of the catalytic oxidation reactions of NAC were monitored by the cyclic voltammetry and chronoamperometry. The catalytic oxidation rate constant k (4.21 ± 0.05) × 103 M−1 s−1 was calculated using electrochemical approaches. The results showed that in 1.0 × 10−3 M of potassium ferricyanide solution, the current signals were proportional to the NAC concentration from 4.4 × 10−4 M to 8.0 × 10−2 M [Ip(10−6 A) = 0.58412 + 5.38 × 103c(M), R2 = 0.9934], and the detection limit (S/N = 3) was 5.02 × 10−5 M. For 80 mM NAC, six successive measurements yielded R.S.D. of 3.4%, which shows that the sensor is reproducible. The proposed method can be applied for the determination of NAC in routine analysis.

Quantitative Analysis of Small Molecular Weight Thiols and Disulfides in Blood from a Sickle Cell Disease Patient Infused with N-Acetyl-L-Cysteine

N-acetyl-L-cysteine (NAC) is an FDA approved drug used to treat acetaminophen overdose or as a mucolytic agent in respiratory disorders. The commonly accepted mechanism of action is that NAC undergoes deacetylation to cysteine, which is then used to synthesize glutathione (GSH), a major intracellular antioxidant. Like other thiol-containing compounds, NAC can also act as a reducing agent to break protein disulfide bonds or as a scavenger of reactive oxygen species. Due to its antioxidant properties, NAC has been proposed as a potential treatment for many diseases associated with oxidative stress, including sickle cell disease (SCD), neurological disorders, infectious diseases, and cancers. Though NAC has been widely studied, a full understanding of the mechanism by which NAC is effective in vivo has been limited by challenges in accurately quantifying NAC and its metabolites.As part of a clinical trial of NAC therapy in SCD, we have developed a liquid chromatography-mass spectrometry (LC-MS) based assay to quantify small molecule free thiols and disulfides using isotopically labeled internal standards. We applied this method to quantify small molecular thiols and disulfides in whole blood, red blood cells, and plasma from a SCD patient before (pre) and at 1, 8, 24 and 72 hr time points of intravenous administration of NAC at a dose of 300 mg/kg (a bolus infusion of 150 mg/kg for 1 hour followed by 150 mg/kg given over the next 7 hr). The cysteine concentration in whole blood increased to 286 μM at 1 hr from 97 μM at baseline, indicating that NAC is indeed rapidly metabolized (deacetylated) to cysteine. Interestingly, although cysteine concentration in RBCs increased over 4 fold at 1 hr and remained high compared to baseline, the highest concentration of total GSH in blood was observed at 24 hr (743 μM compared to 494 μM at baseline). Intracellular availability of cysteine is known as a rate-limiting step for GSH synthesis, and the delayed accumulation of GSH may suggest that NAC is involved in the extracellular deficit of reducing equivalents before it serves as a substrate in GSH synthesis.To explore this possibility, we quantitated NAC and its oxidation products, homo- and mixed disulfides. We found that total NAC concentration reached 1.58 mM in whole blood at 1 hr, but 44% of NAC was oxidized to N-acetyl-cystine (NAC-ss) or formed mixed disulfides with GSH (GS-ss-NAC) and Cys (Cys-ss-NAC), whereas the NAC used for infusion contained less than 0.5% in the oxidized form (NAC-ss). Concurrent with the formation of NAC disulfides, the levels of oxidized GSH (GSSG, GS-ss-Cys) and cysteine (cystine) were significantly decreased. These observations suggest that NAC administration of SCD not only increases GSH levels by raising the cysteine concentration, but also directly functions as an antioxidant to reduce oxidative stress. SCD patients are known to have low levels of GSH and frequently experience oxidative stress. NAC treatment is likely to address both issues. We plan to analyze the effects of NAC on blood small molecule thiol concentrations in several more SCD patients. DisclosuresNo relevant conflicts of interest to declare.

Trace analysis of N-acetyl-L-cysteine using luminol-H2O2 chemiluminescence system catalyzed by silver nanoparticles.

N-Acetyl-L-cysteine (NAC) can inhibit the luminol-H2 O2 , reaction, which is catalyzed by silver nanoparticles. Based on this phenomenon a new method was developed for NAC determination. Under optimum conditions, a linear relationship between chemiluminescence intensity and NAC concentration was found in the range 0.034-0.98 µg/mL. The detection limit was 0.010 µg/mL (S/N =3), and the relative standard deviation (RSD) was <5% for 0.480 µg/mL NAC (n =5). This simple, sensitive and inexpensive method has been applied to measure the concentration of NAC in pharmaceutical tablets.