Smartphone-assisted colorimetric biosensor for the rapid visual detection of natural antioxidants in food samples.

Quantitative monitoring of the concentrations of epigallocatechin gallate (EGCG) and cysteine (Cys) is of great significance for promoting human health. In this study, iron/aluminum bimetallic MOF material MIL-53 (Fe, Al) was rapidly prepared under room temperature using a co-precipitation method, followed by investigating the peroxidase-like (POD-like) activity of MIL-53(Fe, Al) using 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic substrate. The results showed that the Michaelis -Menten constants of TMB and H2O2 as substrates were 0.167 mM and 0.108 mM, respectively. A colorimetric sensing platform for detecting EGCG and Cys was developed and successfully applied for analysis and quantitative detection using a smartphone. The linear detection range for EGCG was 15∼80 µM (R2=0.994) and for Cys was 7∼95 µM (R2=0.998). The limits of detection (LOD) were 0.719 µM and 0.363 µM for EGCG and Cys, respectively. This work provides a new and cost-effective approach for the real-time analysis of catechins and amino acids.

Cysteine triggered cascade reaction forming coumarin: Visualization of cysteine fluctuation in alcoholic liver disease by a NIR fluorescent probe.

Alcoholic liver disease (ALD) is a chronic toxic liver injury caused by long-term heavy drinking. Due to the increasing incidence, ALD is becoming one of important medical tasks. Many studies have shown that the main mechanism of liver damage caused by large amounts of alcohol may be related to antioxidant stress. As an important antioxidant, cysteine (Cys) is involved in maintaining the normal redox balance and detoxifying metabolic function of the liver, which may be closely related to the pathogenesis of ALD. Therefore, it is necessary to develop a simple non-invasive method for rapid monitoring of Cys in liver. Thus, a near-infrared (NIR) fluorescent probe DCI-Ac-Cys which undergoes Cys triggered cascade reaction to form coumarin fluorophore is developed. Using the DCI-Ac-Cys, decreased Cys was observed in the liver of ALD mice. Importantly, different levels of Cys were monitored in the livers of ALD mice taking silybin and curcumin with the antioxidant effects, indicating the excellent therapeutic effect on ALD. This study provides the important references for the accurate diagnosis of ALD and the pharmacodynamic evaluation of silybin and curcumin in the treatment of ALD, and support new ideas for the pathogenesis of ALD.

Oxidative stress-mediated protein sulfenylation in human diseases: Past, present, and future.

Reactive Oxygen Species (ROS) refer to a variety of derivatives of molecular oxygen that play crucial roles in regulating a wide range of physiological and pathological processes. Excessive ROS levels can cause oxidative stress, leading to cellular damage and even cell demise. However, moderately elevated levels of ROS can mediate the oxidative post-translational modifications (oxPTMs) of redox-sensitive proteins, thereby affecting protein functions and regulating various cellular signaling pathways. Among the oxPTMs, ROS-induced reversible protein sulfenylation represents the initial form of cysteine oxidation for sensing redox signaling. In this review, we will summarize the discovery, chemical formation, and detection approaches of protein sulfenylation. In addition, we will highlight recent findings for the roles of protein sulfenylation in various diseases, including thrombotic disorders, diabetes, cardiovascular diseases, neurodegenerative diseases, and cancer.

Organosulfur Compounds, S-Allyl-L-Cysteine and S-Ethyl-L-Cysteine, Target PCSK-9/LDL-R-Axis to Ameliorate Cardiovascular, Hepatic, and Metabolic Changes in High Carbohydrate and High Fat Diet-Induced Metabolic Syndrome in Rats.

Metabolic syndrome (MetS) is an ever-evolving set of diseases that poses a serious health risk in many countries worldwide. Existing evidence illustrates that individuals with MetS have a 30%-40% higher chance of acquiring type 2 diabetes mellitus (T2DM), cardiovascular disease (CVD), or both. This study was undertaken to uncover the regulatory role of natural organosulfur compounds (OSCs), S-allyl-L-cysteine (SAC), and S-ethyl-L-cysteine (SEC), in targeting high carbohydrate high fat (HCHF)-diet-induced MetS-associated risk management. Our findings suggested that SAC and SEC ameliorated HCHF-diet-induced diabetic profiles, plasma lipid and lipoprotein level, liver function, oxidative-stress, inflammatory cytokines, and chemokines including monocyte chemoattractant protein-1 (MCP-1), lipid peroxidation, plasma proprotein convertase subtilisin/kexin type-9 (PCSK-9), and high-sensitivity C-reactive protein (hs-CRP). Moreover, the assessment of the hepatic mRNA expression of the key genes involved in cholesterol homeostasis depicted that SAC and SEC downregulated the PCSK-9 mRNA expression via targeting the expression of HNF-1α, a transcriptional activator of PCSK-9. On the other hand, the LDL-receptor (LDL-R) expression was upregulated through the activation of its transcriptional regulator sterol regulatory element binding protein-2 (SREBP-2). In addition, the activity and the mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme-A reductases (HMG-R) and peroxisome proliferator-activated receptors (PPARs) were also improved by the treatment of SAC and SEC. We concluded that SAC and SEC can protect against MetS via improving the lipid and lipoprotein content, glycemic indices, hepatic function, targeting the inflammatory cascades, and oxidative imbalance, regulation of the mRNA expression of PCSK-9, LDL-R, SREBP-2, HNF-1α, PPARs, and inflammatory biomarkers.

Plant Defensin PgD1 a Biotechnological Alternative Against Plant Pathogens.

Plant defensins are small antimicrobial proteins (AMP) that participate in the immune defense of plants through their antibacterial, antiviral and antifungal activities. PgD1 is a defensin from Picea glauca (Canadian Pine) and has antifungal activity against plant pathogens. This activity positions it as an alternative biotechnological agent to pesticides commonly used against these plant fungi diseases. The present study aimed to recombinantly produce PgD1 in Escherichia coli to characterize its in vitro antifungal potential against different phytopathogens. To achieve this, the coding gene was amplified and cloned into pET30a( +). Recombinant plasmid was subsequently introduced into E. coli for the soluble expression of defensin PgD1. To evaluate the antifungal activity of the expressed protein, the growth inhibition test was used in solid and liquid media for approximately 7 days against significant plant pathogens, that cause significant crop damage including: Botrytis cinerea, Colletotrichum gloeosporioides, Colletotrichum musae, Colletotrichum graminicola and Fusarium oxysporum. Additionally, stability assessments included temperature variation experiments and inhibition tests using dithiothreitol (DTT). The results showed that there was significant inhibition of the fungal species tested when in the presence of PgD1. Furthermore, defensin proved to be resistant to temperature variations and demonstrated that part of its stability is due to its primary structure rich in cysteine ​​residues through the denaturation test with dithiothreitol (DTT) where the antifungal activity of PgD1 defensin was inhibited. These data indicate that recombinant PgD1 could be utilized as a plant protection technology in agriculture.

Simultaneous detection of cysteine and glutathione in food with a two-channel near-infrared fluorescent probe.

L-Cysteine (Cys) and glutathione (GSH) are closely related biological species that widely exist in food and living cells. To simultaneously detect Cys and GSH from different emission channels, we developed a fluorescent probe (BDP-NBD) based on near-infrared BODIPY and 7-nitrobenzofurazan (NBD). Upon nucleophilic substitution reaction with GSH, BDP-NBD generated an emission band at 713 nm, which can be used to determine GSH (0-100 µM) with a low detection limit (34 nM). Different from GSH, BDP-NBD underwent a nucleophilic substitution-rearrangement reaction with Cys, affording two emission bands at 550 nm and 713 nm, respectively. BDP-NBD was successfully employed to quantify Cys and GSH in various food samples with good recoveries (86.6%-104.6%). Besides, BDP-NBD can image Cys and GSH in living cells from two emission channels. Therefore, this work developed a tool for the simultaneous determination of Cys and GSH in both food and living cells so as to ensure food safety and human health.

Co-cold extrusion synergized with cysteine for enhancing physicochemical, rheological characteristics and in vitro digestibility of whey protein isolate.

Impacts of co-cold extrusion (≤50 °C) of whey protein isolate (WPI) and cysteine (Cys, 0, 20, 40, 60, 80 and 100 mmol/L) on its physicochemical, in vitro digestion and rheological properties were investigated. As Cys concentration increased, the emulsifying properties and in vitro digestibility of co-extruded WPI-Cys products showed an increasing trend. Specifically, when Cys reached 100 mmol/L, surface hydrophobicity, emulsification activity index (EAI), emulsification stability index (ESI) and in vitro stomach digestibility of the co-extruded WPI-Cys products increased by 205.07%, 77.51%, 193.95% and 71.81% compared with WPI, respectively. Principal component analysis (PCA) results further indicated that co-extruded WPI-Cys at a concentration of 100 mmol/L had the best functional properties. In addition, co-extruded WPI-Cys exhibited the strongest Péclet number (Pe) value and apparent viscosity at a Cys concentration of 100 mmol/L among all samples. Therefore, co-extrusion would be an effective method for modifying WPI, providing whey protein-based ingredients with excellent functional properties for food processing.

Cystine/cysteine metabolism regulates the progression and response to treatment of triple­negative breast cancer (Review).

Breast cancer is the most prevalent neoplasm affecting women globally, of which a notable proportion of cases are triple-negative breast cancer (TNBC). However, there are limited curative treatment options for patients with TNBC, despite advancements in the field. Amino acids and amino acid transporters serve vital roles in the regulation of tumor metabolism. Notably, cystine and cysteine can interconvert via a redox reaction, with cysteine exerting control on cell survival and growth and exogenous cystine serving a crucial role in the proliferation of numerous types of cancers. Breast cancer has been reported to disrupt the cystine/cysteine metabolism pathway, as cystine and cysteine transporters affect the development and growth of tumors. The present review aims to provide a comprehensive overview of the metabolic pathways involving cystine and cysteine in normal and TNBC cells. Furthermore, the roles of cystine and cysteine transporters in TNBC progression and metastasis and their potential as therapeutic targets for treatment of TNBC are evaluated.

Exploring the roles of SPARC as a proinflammatory factor and its potential as a novel therapeutic target against cardiovascular disease.

Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of CVD patients continues to increase despite extensive research and developments in this field. Chronic inflammation is a pivotal pathological component of CVD, and unveiling new proinflammatory factors will help devise novel preventive and therapeutic strategies. The extracellular matrix (ECM) not only provides structural support between cells, but also contributes to cellular functions. Secreted protein acidic and rich in cysteine (SPARC) is a collagen-binding matricellular protein that is particularly induced during development and tissue remodeling. A proinflammatory role for SPARC has been demonstrated in various animal models, such as in the lipopolysaccharide-induced footpad model and dextran sodium sulfate-induced colitis model. Recent clinical studies reported a positive correlation between elevated plasma SPARC levels and hypertension, obesity, and the inflammatory marker high-sensitive C-reactive protein. In addition, SPARC gene deletion attenuates the cardiac injury induced by aging, myocardial infarction, and pressure-load, suggesting that SPARC has deleterious effects on CVD. This review summarizes the regulatory and proinflammatory mechanisms of SPARC on CVD, chronic kidney disease (CKD) and cerebrovascular disease, and discusses the rationale behind measuring SPARC as a biomarker of CVD, and the effects of inhibition of SPARC in the prevention and treatment of CVD.

Identifying Quinones in Complex Aqueous Environmental Media (Biochar Extracts) through Tagging with Cysteine and Cysteine-Contained Peptides and High Resolution Mass Spectrometry Analysis.

Quinones are among the most important components in natural organic matter (NOM) for redox reactions; however, no quinones in complex environmental media have been identified. To aid the identification of quinone-containing molecules in ultracomplex environmental samples, we developed a chemical tagging method that makes use of a Michael addition reaction between quinones and thiols (-SH) in cysteine (Cys) and cysteine-contained peptides (CCP). After the tagging, candidates of quinones in representative aqueous environmental samples (water extractions of biochar) were identified through high-resolution mass spectrometry (HRMS) analysis. The MS and UV spectra analysis showed rapid reactions between Cys/CCP and model quinones with ß-carbon from the same benzene ring available for Michael addition. The tagging efficiency was not influenced by other co-occurring nonquinone representative compounds, including caffeic acid, cinnamic acid, and coumaric acid. Cys and CCP were used to tag quinones in water extractions of biochars, and possible candidates of quinones (20 and 53 based on tagging with Cys and CCP, respectively) were identified based on the HRMS features for products of reactions with Cys/CCP. This study has successfully demonstrated that such a Michael addition reaction can be used to tag quinones in complex environmental media and potentially determine their identities. The method will enable an in-depth understanding of the redox chemistry of NOM and its critical chemical compositions and structures.

Genomic and physiological properties of Anoxybacterium hadale gen. nov. sp. nov. reveal the important role of dissolved organic sulfur in microbial metabolism in hadal ecosystems.

Hadal zones account for the deepest 45% of the oceanic depth range and play an important role in ocean biogeochemical cycles. As the least-explored aquatic habitat on earth, hadal ecosystems contain a vast diversity of so far uncultured microorganisms that cannot be grown on conventional laboratory culture media. Therefore, it has been difficult to gain a true understanding of the detailed metabolic characteristics and ecological functions of those difficult-to-culture microorganisms in hadal environments. In this study, a novel anaerobic bacterial strain, MT110T, was isolated from a hadal sediment-water interface sample of the Mariana Trench at 10,890 m. The level of 16S rRNA gene sequence similarity and percentage of conserved proteins between strain MT110T and the closest relatives, Anaerovorax odorimutans DSM 5092T (94.9 and 46.6%) and Aminipila butyrica DSM 103574T (94.4 and 46.7%), indicated that strain MT110T exhibits sufficient molecular differences for genus-level delineation. Phylogenetic analyses based on both 16S rRNA gene and genome sequences showed that strain MT110T formed an independent monophyletic branch within the family Anaerovoracaceae. The combined evidence showed that strain MT110T represents a novel species of a novel genus, proposed as Anoxybacterium hadale gen. nov. sp. nov. (type strain MT110T = KCTC 15922T = MCCC 1K04061T), which represents a previously uncultured lineage of the class Clostridia. Physiologically, no tested organic matter could be used as sole carbon source by strain MT110T. Genomic analysis showed that MT110T had the potential capacity of utilizing various carbon sources, but the pathways of sulfur reduction were largely incomplete. Our experiments further revealed that cysteine is one of the essential nutrients for the survival of strain MT110T, and cannot be replaced by sulfite, leucine, or taurine. This result suggests that organic sulfur compounds might play an important role in metabolism and growth of the family Anaerovoracaceae and could be one of the key factors affecting the cultivation of the uncultured microbes. Our study brings a new perspective to the role of dissolved organic sulfur in hadal ecosystems and also provides valuable information for optimizing the conditions of isolating related microbial taxa from the hadal environment.

Low swelling and high mechanical strength organosilane hybrid polydivinylbenzene microspheres for hydrophilic interaction chromatography applications.

In this work, monodisperse organosilane hybrid polymer microspheres with a particle size of about 5 µm were synthesized using seed swelling polymerization. The organosilicon reagent methacryloxypropyltrimethoxysilane was introduced into the polymer framework as a copolymerization monomer, and the crosslinking degree of the microspheres was improved by the hydrolysis-condensation reaction of siloxanes. The synthesized hybrid microspheres have good mechanical strength as well as low swelling, with swelling propensity values of 0.167 and 0.348 in methanol and acetonitrile, respectively. Hybrid microspheres modified with cysteine have a hydrophilic interaction chromatography/reversed-phase liquid chromatography mixed-mode retention mechanism. Compared to the commercial cysteine-modified silica column, the synthesized stationary phase has higher separation selectivity for partially acidic or basic samples and better basic resistance for use under high pH mobile phase conditions (at least 10).

To Explore Potential Natural Inhibitors of Cysteine Proteases to Combat Human African Trypanosomiasis and Chagas Disease.

BACKGROUND: Human African Trypanosomiasis (HAT), also known as sleeping sickness, and Chagas disease are neglected tropical diseases caused by Trypanosoma brucei and Trypanosoma cruzi, respectively. These diseases present significant challenges in treatment due to the toxicity, low efficacy, and drug-resistant strains associated with current therapies. INTRODUCTION: Cysteine proteases play vital roles in the life cycles of these parasites, making them potential targets for therapeutic intervention. Natural inhibitors sourced from plants, marine organisms, and microorganisms show promise for developing novel therapies. METHODS: This review surveys the potential of natural inhibitors as therapeutic agents against HAT and Chagas disease. It compiles PubMed and PubChem information from various studies to provide an overview of their activities and characteristics, including their ability to inhibit cysteine proteases, modulate the host immune response, and interfere with other parasite proteins. RESULTS: Several natural inhibitors, such as berberine, curcumin, and tannins, have been identified and characterized. These inhibitors have demonstrated encouraging outcomes in both in vitro and in vivo experiments, indicating their potential as therapeutic agents for HAT and Chagas disease. CONCLUSION: Natural inhibitors of cysteine proteases offer a promising avenue for developing novel therapies against HAT and Chagas disease. Further research is needed to identify additional natural inhibitors and optimize their efficacy and safety for human use. The significance of this study lies in its potential to contribute to the discovery of effective, safe, and affordable treatments for these neglected tropical diseases.

The Facile Production of p-Chloroaniline Facilitated by an Efficient and Chemoselective Metal-Free N/S Co-Doped Carbon Catalyst.

The catalytic hydrogenation of the toxic and harmful p-chloronitrobenzene to produce the value-added p-chloroaniline is an essential reaction for the sustainable chemical industry. Nevertheless, ensuring satisfactory control of its chemoselectivity is a great challenge. In this work, a N/S co-doped metal-free carbon catalyst has been fabricated by using cysteine as a source of C, N, and S. The presence of calcium citrate (porogen agent) in the mixture subjected to pyrolysis provided the carbon with porosity, which permitted us to overcome the issues associated with the loss of heteroatoms during an otherwise necessary activation thermal treatment. Full characterization was carried out and the catalytic performance of the metal-free carbon material was tested in the hydrogenation reaction of p-chloronitrobenzene to selectively produce p-chloroaniline. Full selectivity was obtained but conversion was highly dependent on the introduction of S due to the synergetic effect of S and N heteroatoms. The N/S co-doped carbon (CYSCIT) exhibits a mesoporous architecture which favors mass transfer and a higher doping level, with more exposed N and S doping atoms which act as catalytic sites for the hydrogenation of p-chloronitrobenzene, resulting in enhanced catalytic performance when compared to the N-doped carbon obtained from melamine and calcium citrate (MELCIT) used as a reference.

Non-standard amino acid incorporation into thiol dioxygenases.

Thiol dioxygenases (TDOs) are non­heme Fe(II)­dependent enzymes that catalyze the O2-dependent oxidation of thiol substrates to their corresponding sulfinic acids. Six classes of TDOs have thus far been identified and two, cysteine dioxygenase (CDO) and cysteamine dioxygenase (ADO), are found in eukaryotes. All TDOs belong to the cupin superfamily of enzymes, which share a common ß­barrel fold and two cupin motifs: G(X)5HXH(X)3-6E(X)6G and G(X)5-7PXG(X)2H(X)3N. Crystal structures of TDOs revealed that these enzymes contain a relatively rare, neutral 3­His iron­binding facial triad. Despite this shared metal-binding site, TDOs vary greatly in their secondary coordination spheres. Site­directed mutagenesis has been used extensively to explore the impact of changes in secondary sphere residues on substrate specificity and enzymatic efficiency. This chapter summarizes site-directed mutagenesis studies of eukaryotic TDOs, focusing on the tools and practicality of non­standard amino acid incorporation.

The cell-permeant antioxidant D-thiol ester D-cysteine ethyl ester overcomes physical dependence to morphine in male Sprague Dawley rats.

The ability of morphine to decrease cysteine transport into neurons by inhibition of excitatory amino acid transporter 3 (EAA3) may be a key molecular mechanism underlying the acquisition of physical and psychological dependence to morphine. This study examined whether co-administration of the cell-penetrant antioxidant D-thiol ester, D-cysteine ethyl ester (D-CYSee), with morphine, would diminish the development of physical dependence to morphine in male Sprague Dawley rats. Systemic administration of the opioid receptor antagonist, naloxone (NLX), elicited pronounced withdrawal signs (e.g., wet-dog shakes, jumps, rears, circling) in rats that received a subcutaneous depot of morphine (150 mg/kg, SC) for 36 h and continuous intravenous infusion of vehicle (20 µL/h, IV). The NLX-precipitated withdrawal signs were reduced in rats that received an infusion of D-CYSee, but not D-cysteine, (both at 20.8 µmol/kg/h, IV) for the full 36 h. NLX elicited pronounced withdrawal signs in rats treated for 48 h with morphine (150 mg/kg, SC), plus continuous infusion of vehicle (20 µL/h, IV) that began at the 36 h timepoint of morphine treatment. The NLX-precipitated withdrawal signs were reduced in rats that received a 12 h infusion of D-CYSee, but not D-cysteine, (both at 20.8 µmol/kg/h, IV) that began at the 36 h timepoint of morphine treatment. These findings suggest that D-CYSee may attenuate the development of physical dependence to morphine and reverse established dependence to the opioid in male Sprague Dawley rats. Alternatively, D-CYSee may simply suppress the processes responsible for NLX-precipitated withdrawal. Nonetheless, D-CYSee and analogues may be novel therapeutics for the treatment of opioid use disorders.

Developing a vanillin-derived imidazo-pyridin-containing fluorescent probe for imaging cysteine in living pulmonary cells under oxygen supply variation.

In this work, derived from vanillin and imidazo-pyridin backbone, a fluorescent probe IPV-Cys was developed for imaging the cysteine (Cys) level in living pulmonary cells under oxygen supply variation. By mimicking the oxygen supply variation in both the solution test and cellular imaging, the optical performance and imaging effect of IPV-Cys was investigated. In the solution system, the oxygen supply variation caused no impact on the reporting signals. The fluorescence reporting signal intensity at 490 nm suggested the enhancement along with the increase of the Cys concentration. The advantages of IPV-Cys included relatively high sensitivity, high stability, and high selectivity. On the basis of the low cyto-toxicity, IPV-Cys achieved the monitoring the endogenous Cys level in in living pulmonary cells and the impact of the oxygen supply variation by reporting fluorescence signals. The information here was meaningful for both the pre-clinical diagnosis and surgical techniques.

Mining unique cysteine synthetases and computational study on thoroughly eliminating feedback inhibition through tunnel engineering.

L-cysteine is an essential component in pharmaceutical and agricultural industries, and synthetic biology has made strides in developing new metabolic pathways for its production, particularly in archaea with unique O-phosphoserine sulfhydrylases (OPSS) as key enzymes. In this study, we employed database mining to identify a highly catalytic activity OPSS from Acetobacterium sp. (AsOPSS). However, it was observed that the enzymatic activity of AsOPSS suffered significant feedback inhibition from the product L-cysteine, exhibiting an IC50 value of merely 1.2 mM. A semi-rational design combined with tunnel analysis strategy was conducted to engineer AsOPSS. The best variant, AsOPSSA218R was achieved, totally eliminating product inhibition without sacrificing catalytic efficiency. Molecular docking and molecular dynamic simulations indicated that the binding conformation of AsOPSSA218R with L-cys was altered, leading to a reduced affinity between L-cysteine and the active pocket. Tunnel analysis revealed that the AsOPSSA218R variant reshaped the landscape of the tunnel, resulting in the construction of a new tunnel. Furthermore, random acceleration molecular dynamics simulation and umbrella sampling simulation demonstrated that the novel tunnel improved the suitability for product release and effectively separated the interference between the product release and substrate binding processes. Finally, more than 45 mM of L-cysteine was produced in vitro within 2 h using the AsOPSSA218R variant. Our findings emphasize the potential for relieving feedback inhibition by artificially generating new product release channels, while also laying an enzymatic foundation for efficient L-cysteine production.

Electrocatalytic efficiency of carbon nitride supported gold nanoparticle based sensor for iodide and cysteine detection.

Extensive investigations are being conducted on gold nanoparticles focusing on their applications in biosensors, laser phototherapy, targeted drug delivery and bioimaging utilizing advanced detection techniques. In this work, an electrochemical sensor was developed based on graphite carbon nitride supported gold nanoparticles. Carbon nitride supported gold nanoparticles (Au-CN) was synthesized by applying a deposition-precipitation route followed by a chemical reduction technique. The composite system was characterized by X-ray diffraction and X-ray photo electron spectroscopy methods. Electron microscopy analysis confirmed the formation of gold nanoparticles within the size range of 5-15 nm on the carbon nitride support. Carbon nitride supported gold based sensor was employed for the electrochemical detection of iodide ion and l-cysteine. The limit of detection and sensitivity of the sensor was attained 8.9 µM and 0.96 µAµM⁻1cm⁻2, respectively, for iodide ion, while 0.48 µM and 5.8 µAµM⁻1cm⁻2, respectively, was achieved for the recognition of cysteine. Furthermore, a paper-based electrochemical device was developed using the Au-CN hybrid system that exhibited promising results in detecting iodide ions, highlighting its potential for economic and portable device applications.

Assessment of the antimicrobial and antibiofilm activity of the combination of N-acetyl cysteine and carvacrol against Staphylococcus aureus, the most common orthopedic infectious agent.

BACKGROUND: The increasing prevalence of antibiotic-resistant bacterial infections has led to the search for new approaches. OBJECTIVE: This study aimed to evaluate the effects of carvacrol and N-acetyl cysteine, both individually and in combination, on the planktonic cells and biofilm formations of Staphylococcus aureus, including methicillin-resistant and methicillin-sensitive strains. Additionally, the study sought to perform cytotoxicity tests and chemical characterization to further understand the properties and potential applications of these substances. METHODS: A total of 19 S. aureus strains were included in the study. Minimum inhibitory concentration and minimum bactericidal concentration were determined by assays. Synergy analysis tests were carried out. Cytotoxicity tests were conducted on the fibroblast cell line. Characterization test was performed. RESULTS: While Minimum inhibitory concentration and minimum bactericidal concentration values for carvacrol varied between 250-500 µg/ml, these values were in the range of 32-64 mg/ml for N-acetyl cysteine. Biofilm formation activities were identified. A total of eight strains, including six clinical and two standard strains with the highest biofilm-forming ability, were selected for combination studies. The combination of Carvacrol and N-acetyl cysteine exhibited synergistic and partially synergistic effects on the tested planktonic and biofilm strains, and these effects were dose-dependent. Carvacrol was found to be the most active drug at the end of 24, 48, and 72 hours. Regarding the synergistic effect of N-acetyl cysteine +carvacrol, it was revealed to exhibit higher activity than N-acetyl cysteine and lower activity than carvacrol. CONCLUSION: The combination of carvacrol and N-acetyl cysteine demonstrated synergistic and partially synergistic effects against both planktonic and biofilm forms of Staphylococcus aureus. These results suggest potential for novel approaches in managing orthopedic infections, warranting further research to explore their therapeutic applications.