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Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for the renewal of the authorisation of l‐cystine as nutritional feed additive. The additive is authorised for use in all animal species (3c391). The applicant has provided evidence that the additive currently in the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed concluded that the use of the feed additive in animal nutrition remains safe for the target species, the consumers and the environment. As regards the safety for the user, l‐cystine is not an irritant to skin or eyes and is not a skin sensitiser. Exposure by inhalation of persons handling the additive cannot be excluded. The present application for the renewal of the authorisation does not include any modification proposal that would have an impact on the efficacy of the additive and therefore there is no need for reassessing the efficacy. [ABSTRACT FROM AUTHOR]

Abstract Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the assessment of the application for the renewal of the authorisation of l‐cystine as nutritional feed additive. The additive is authorised for use in all animal species (3c391). The applicant has provided evidence that the additive currently in the market complies with the existing conditions of authorisation. The EFSA Panel on Additives and Products or Substances used in Animal Feed concluded that the use of the feed additive in animal nutrition remains safe for the target species, the consumers and the environment. As regards the safety for the user, l‐cystine is not an irritant to skin or eyes and is not a skin sensitiser. Exposure by inhalation of persons handling the additive cannot be excluded. The present application for the renewal of the authorisation does not include any modification proposal that would have an impact on the efficacy of the additive and therefore there is no need for reassessing the efficacy.

Kidney stone diseases are increasing globally in prevalence and recurrence rates, indicating an urgent medical need for developing new therapies that can prevent stone formation. One approach we have been working on is to develop small molecule inhibitors that can interfere with the crystallization process of the chemical substances that form the stones. For these drug discovery efforts, it is critical to have available easily accessible assay methods to evaluate the potential inhibitors and rank them for structure-activity relationship studies. Herein, we report a convenient, medium-to-high throughput assay platform using, as an example, the screening and evaluation of inhibitors of L-cystine crystallization for the prevention of kidney stones in cystinuria. The assay involves preparing a supersaturated solution, followed by incubating small volumes (<1 mL) of the supersaturated solution with test inhibitors for 72 hours, and finally measuring L-cystine concentrations in the supernatants after centrifugation using either a colorimetric or fluorometric method. Compared to traditional techniques for studying crystallization inhibitors, this miniaturized multi-well assay format is simple to implement, cost-effective, and widely applicable in determining and distinguishing the activities of compounds that inhibit crystallization. This assay has been successfully employed to discover L-cystine diamides as highly potent inhibitors of L-cystine crystallization such as LH708 with an EC50 of 0.058 µM, 70-fold more potent than L-CDME (EC50 = 4.31 µM). [ABSTRACT FROM AUTHOR]

Cystine-enriched food supplements are increasingly popular due to their beneficial health effects. However, the lack of industry standards and market regulations resulted in quality issues with cystine food products, including cases of food adulteration and fraud. This study established a reliable and practical method for determining cystine in food supplements and additives using quantitative NMR (qNMR). With the optimized testing solvent, acquisition time, and relaxation delay, the method exhibited higher sensitivity, precision, and reproducibility than the conventional titrimetric method. Additionally, it was more straightforward and more economical than HPLC and LC-MS. Furthermore, the current qNMR method was applied to investigate different food supplements and additives regarding cystine quantity. As a result, four of eight food supplement samples were found to be inaccurately labeled or even with fake labeling, with the relative actual amount of cystine ranging from 0.3% to 107.2%. In comparison, all three food additive samples exhibited satisfactory quality (the relative actual amount of cystine: 97.0–99.9%). Notably, there was no obvious correlation between the quantifiable properties (price and labeled cystine amount) of the tested food supplement samples and their relative actual amount of cystine. The newly developed qNMR-based approach and the subsequent findings might help standardization and regulation of the cystine supplement market. [ABSTRACT FROM AUTHOR]

The sulfur electric‐field‐gradient tensor for a disulfide bond in 33S2‐labeled L‐cystine has been investigated by 33S nuclear quadrupole resonance (NQR). 33S2‐labeled L‐cystine is synthesized by introduction of disulfide ions prepared from elemental 33S‐sulfur into an amino acid derivative, the side chain of which is iodinated. In its NQR spectrum, sharp single peaks are observed at between 24.63 and 24.90 MHz in the temperature range from 80 to 298 K. The two‐dimensional nutation echo 33S NQR experiment is carried out at 160 K, and the quadrupole coupling constant, CQ, and the asymmetric parameter, ηQ, are obtained to be 46.9(9) MHz and 0.6(1), respectively. The calculated 33S electric‐field‐gradient tensor components with respect to the molecular frame is briefly discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] The reaction of L-cysteine with sodium thiosulfate in aqueous solution at pH 9 affords mainly L-cystine with noticeable amounts of L-cysteine sulfonic anion –O 2 CCH(NH+)CH SO–. NMR study revealed the formation of intermediate L-cysteine sulfenic acid and L-cysteine S -sulfite, the latter existing in two active forms –O 2 CCH(NH 2)CH 2 S(=S)O– and –O CCH(NH)CH SSO–. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sensing of biomarker L-cystine for the early diagnosis of cystinuria. • Development of thioglycolated-β-CD anchored silver nanoparticles as the nano biosensor. • Offers both recognition and quantification of L-cystine by spectroscopic fingerprinting. • Provides naked-eye detection by indicator displacement assay. • Cellulose paper-dye test strip is developed for use in point-of-care units. Accurate sensing of small biomolecules from complex biofluid media remains a challenge due to adverse interaction of metallic salts and other biofluid components. L-cystine is the most important biomarker for the disease cystinuria. Recognition of L-cystine in urine is thus fundamental for the timely detection of cystinuria and related chronic kidney disease (CKD). Poor solubility of L-cystine offer limits to design suitable sensors. Herein, we report the synthesis of thioglycolated-β-CD (TG-β-CD) anchored silver nanoparticles (AgNP) as a potential receptor (TG-β-CD ⊃ AgNP) for the effective optical recognition and quantification of L-cystine through UV–Vis and SERS (surface enhanced Raman spectroscopy) spectroscopic fingerprinting and suitable colourimetric naked-eye detection of L-cystine by indicator displacement assay. Methyl orange (Met-O) indicator was precomplexed with the receptor to generate the probe solution (Met-O@TG-β-CD ⊃ AgNP). Indicator has been exchanged from Met-O@TG-β-CD ⊃ AgNP by the addition of L-cystine, with an instantaneous visible colour change from yellow to red. The method is tolerable to other interfering abundant ions and biomolecules. Based on the innovative sensing assay a cellulose paper-dye test strip is developed for point-of-care detection and quantification of the biomarker. Structures of TG-β-CD, TG-β-CD ⊃ AgNP and Met-O@TG-β-CD ⊃ AgNP were elucidated by UV–Vis, FT-IR, PXRD, 1H NMR, etc. spectroscopy. Scanning electron microscopy (SEM) was used to examine the morphology of TG-β-CD, AgNP and TG-β-CD ⊃ AgNP. The chemical changes during the assay were evaluated by conductance, UV–Vis and SERS. The competitive displacement of the indicator and UV turn-on at ppm level analyte concentration made the process compatible for day-to-day point-of-care units. [ABSTRACT FROM AUTHOR]

Gestational diabetes mellitus (GDM) disrupts glucolipid metabolism, endangering maternal and fetal health. Despite limited research on its pathogenesis and treatments, we conducted a study using serum samples from GDM-diagnosed pregnant women. We performed metabolic sequencing to identify key small molecule metabolites and explored their molecular interactions with FGF21. We also investigated FGF21's impact on GDM using blood samples from affected women. Our analysis revealed a novel finding: elevated levels of L-Cystine in GDM patients. Furthermore, we observed a positive correlation between L-Cystine and FGF21 levels, and found that L-Cystine induces NRF2 expression via FGF21 for a period of 96 h. Under high glucose (HG) conditions, FGF21 upregulates NRF2 and downstream genes NQO1 and EPHX1 via AKT phosphorylation induced by activation of IRS1, enhancing endothelial function. Additionally, we confirmed that levels of FGF21, L-Cystine, and endothelial function at the third trimester were effectively enhanced through appropriate exercise and diet during pregnancy in GDM patients (GDM + ED). These findings suggest FGF21 as a potential therapeutic agent for GDM, particularly in protecting endothelial cells. Moreover, elevated L-Cystine via appropriate exercise and diet might be a potential strategy to enhance FGF21's efficacy. The schematic diagram illustrates the protective effect of FGF21 on HUVEC under high sugar conditions. A hyperglycemic environment can induce functional damage and oxidative stress to placental endothelial cells, impairing their function and leading to apoptosis. This study revealed that L-Cystine (induced by exercise and diet) could enhance endogenous expression of FGF21 and NRF2, but did not significantly improve cell phenotype. Adequate exogenous FGF21 and endogenous FGF21 can regulate NRF2 by promoting AKT phosphorylation through IRS1, facilitating its nuclear translocation, and transcription of downstream antioxidant genes (EPHX1, NQO1, AKR1A1 , et al), thereby inhibiting the production of ROS and HUVECs apoptosis while promoting HUVECs migration to ameliorate endothelial function and angiogenesis. [Display omitted] • L-Cystine modestly up-regulates FGF21 under HG induced stress, improving endothelial dysfunction over a prolonged period. • Adequate exogenous FGF21 prevents GDM-induced endothelial dysfunction and confers resistance against oxidative stress. • Nrf2 plays a pivotal role in the improvement of endothelial function by FGF21 under GDM conditions. • FGF21 modulates the nuclear localization of Nrf2 under high glucose conditions through IRS1/Akt signaling pathway. • Proper exercise and diet during pregnancy effectively enhance FGF21 and L-Cystine in GDM patients at the second trimester. [ABSTRACT FROM AUTHOR]

Cystine-enriched food supplements are increasingly popular due to their beneficial health effects. However, the lack of industry standards and market regulations resulted in quality issues with cystine food products, including cases of food adulteration and fraud. This study established a reliable and practical method for determining cystine in food supplements and additives using quantitative NMR (qNMR). With the optimized testing solvent, acquisition time, and relaxation delay, the method exhibited higher sensitivity, precision, and reproducibility than the conventional titrimetric method. Additionally, it was more straightforward and more economical than HPLC and LC-MS. Furthermore, the current qNMR method was applied to investigate different food supplements and additives regarding cystine quantity. As a result, four of eight food supplement samples were found to be inaccurately labeled or even with fake labeling, with the relative actual amount of cystine ranging from 0.3% to 107.2%. In comparison, all three food additive samples exhibited satisfactory quality (the relative actual amount of cystine: 97.0–99.9%). Notably, there was no obvious correlation between the quantifiable properties (price and labeled cystine amount) of the tested food supplement samples and their relative actual amount of cystine. The newly developed qNMR-based approach and the subsequent findings might help standardization and regulation of the cystine supplement market.

It is assumed that genetic diseases affecting the metabolism of cysteine and the kidney function lead to two different kinds of pathologies, namely cystinuria and cystinosis whereby generate l-cystine crystals. Recently, the presence of l-cysteine crystal has been underlined in the case of cystinosis. Interestingly, it can be strikingly seen that cystine ([–S–CH2–CH–(NH2)–COOH]2) consists of two cysteine (C3H7NO2S) molecules connected by a disulfide (S–S) bond. Therefore, the study of cystine and cysteine is important for providing a better understanding of cystinuria and cystinosis. In this paper, we elucidate the discrepancy between l-cystine and l-cysteine by investigating the theoretical and experimental infrared spectra (IR), X-ray diffraction (XRD) as well as Raman spectra aiming to obtain a better characterization of abnormal deposits related to these two genetic pathologies. [ABSTRACT FROM AUTHOR]

The reaction of L-cysteine solution with the iron(III) compounds FeCl3, Fe2(SO4)3, and Fe(NO3)3 in an acidic medium (pH 2) was studied. The reaction was complete in 30 min and formed L-cystine (21–40%) as the main product. The reaction of L-cysteine with FeCl3 formed L-cysteine sulfonic acid in the solution as a by-product. The products from the reaction of L-cysteine with the Fe(III) compounds were interpreted by IR and NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Boron nitride nanotubes (BNNTs), the structural analogues to carbon nanotubes (CNTs), attracted considerable attention due to their excellent properties. However, the synthesis of BNNTs suffers from high-temperature requirement, which increases the cost and adds complexity to instruments (arc-discharge, plasma-assisted CVD, etc.), preventing further exploration of BNNTs and use of harmful chemicals (catalytic chemical vapor deposition) resulting in unwanted byproducts. Here, we demonstrate sulfur-containing compound-assisted synthesis of BNNTs at a relatively low temperature of 1050 °C from colemanite via a chemical vapor deposition (CVD) method. Comparison between thiophene, l-cystine, and l-methionine revealed that thiophene is the most effective sulfur compound with more stable decomposition products and low vapor pressure. Moreover, we have evaluated ulexite and etidot-67 as an alternative to colemanite. We believe that our findings can offer solutions to commonly encountered problems of BNNT synthesis in terms of high energy consumption and precursor cost, leading to broader use of BNNTs in various applications. [ABSTRACT FROM AUTHOR]

Background: Glutathione has become a potential skin‐lightening ingredient after the discovery of its anti‐melanogenic properties. Various mechanisms of action have been considered to explain this property, one of them being the skewing of the melanin synthesis pathway toward the production of lighter pheomelanin instead of darker eumelanin, consequently producing a lightening effect. Aims: To evaluate the skin lightening and anti‐dark spot effects of oral supplementation with L‐Cystine associated with L‐Glutathione as compared to placebo and benchmark. Methods: Effects of this L‐Cystine‐L‐Glutathione oral combination were investigated in a 12‐week randomized, double‐blind, parallel‐group, benchmark‐ and placebo‐controlled trial involving 124 Asian female subjects. Women were randomly allocated into 4 equal groups (500 mg L‐Cystine and 250 mg L‐Glutathione, 250 mg reduced L‐Glutathione, 500 mg L‐Cystine, or a placebo, daily). Skin color was measured at baseline, after 6 and 12 weeks by spectrophotometry. Size and color of facial dark spots were determined from digital photographs. Results: A significant skin lightening was observed after 12 weeks of oral supplementation with L‐Cystine associated with L‐Glutathione. This combination also induced a significant reduction in the size of facial dark spots after 6 and 12 weeks. It is noteworthy that the observed effects were not only significantly better than those obtained with placebo, but also with L‐Cystine alone or L‐Glutathione alone. Conclusion: The daily oral administration of 500 mg L‐Cystine and 250 mg L‐Glutathione during 12 weeks was a safe treatment to effectively lighten the skin and reduce the size of facial dark spots of Asian women. [ABSTRACT FROM AUTHOR]

Background: Hydrogen sulfide (H2S) is a pivotal gasotransmitter networking with nitric oxide (NO) and carbon monoxide (CO) to regulate basic homeostatic functions. It is released by the alternative pathways of transulfuration by the enzymes Cystathionine Beta Synthase (CBS) and Cystathionine Gamma Lyase (CSE), and by Cysteine AminoTransferase (CAT)/ 3-Mercaptopyruvate Sulfur Transferase (3MPST). A non-enzymatic, intravascular release is also in place. We retrospectively investigated the possibility to modulate the endogenous H2S release and signaling in humans by a dietary manipulation with supplemented micronutrients (L-cystine, Taurine and pyridoxal 5-phopsphate/P5P). Methods: Patients referring for antiaging purposes underwent a 10-day supplementation. Blood was collected at baseline and after treatment and the metabolome was investigated by mass spectrometry to monitor the changes in the metabolites reporting on H2S metabolism and related pathways. Results: Data were available from 6 middle aged subjects (2 women). Micronutrients increased 3-mercaptopyruvate (P =.03), reporting on the activity of CAT that provides the substrate for H2S release within mitochondria by 3MPST, decreased lanthionine (P =.024), reporting the release of H2S from CBS, and had no significant effect of H2S release from CSE. This is compatible with a homeostatic balancing. We also recorded a strong increase of reporters of H2S-induced pathways including 5-MethylTHF (P =.001) and SAME (P =.022), reporting on methylation capacity, and of BH4 (P =.021) and BH2 (P =.028) reporting on nitric oxide metabolism. These activations may be explained by the concomitant induction of non-enzymatic release of H2S. Conclusions: Although the current evidences are weak and will need to be confirmed, the effect of micronutrients was compatible with an increase of the H2S endogenous release and signaling within the control of homeostatic mechanisms, further endorsing the role of feeding in health and disease. These effects might result in a H2S boosting effect in case of defective activity of pathologic origin, which should be checked in duly designed clinical trials. [ABSTRACT FROM AUTHOR]

Nitroaromatic chemicals, including 4-nitrophenol (4-NP) and dyes, pose substantial risks to human health and the environment. Various catalysts that facilitate the reduction of 4-NP to 4-aminophenol (4-AP) have been documented to reduce its toxicity. Herein, we developed a novel nanocomposite consisting of needle-like copper oxide nanorods immobilized with L-cystine functionalized polyglycidyl methacrylate integrated graphene oxide (Cys-PGMA@GO-CuO) nanocomposite. The formation of this nanocomposite was comprehensively characterized using various analytical techniques. X-ray diffraction revealed a semi-crystalline nature for pure PGMA/GO with a prominent peak at 2θ = 19.25°. The introduction of inherently crystalline CuO nanoparticles in Cys-PGMA@GO-CuO rendered the entire composite completely crystalline. Further, the photocatalytic efficiency of the Cys-PGMA@GO-CuO nanocomposite was evaluated through advanced oxidation processes (AOP) for treating various toxic pollutants in wastewater remediation. The nanocomposite efficiently degraded dyes like methyl orange (99.8%) and methylene blue (99.9%) in just 50 mins and reduced toxic 4-NP to 4-AP within 40 mins. We further investigated the optimal degradation conditions based on [oxidant], [dye], and the presence of scavengers to understand the rate of degradation. Notably, the composite exhibited remarkable recyclability and stability. The performance of Cys-PGMA@GO-CuO was further evaluated using real wastewater samples, achieving a remarkable decolorization of 99.5% in textile dyeing wastewater and 97.1% in methylene blue-contaminated tap water. These results demonstrate the promising potential of this nanocomposite as an economically viable alternative approach for removing various organic pollutants from wastewater. Additionally, its successful application in real water sample analysis suggests its significant potential for practical implementation in water treatment processes. [Display omitted] [ABSTRACT FROM AUTHOR]

Recently, many efforts have been dedicated to creating enzyme-mimicking catalysts to replace natural enzymes in practical fields. Inspired by the pathological biomineralization behaviour of l-cystine, in this study, we constructed a laccase-like catalyst through the co-assembly of l-cystine with Cu ions. Structural analysis revealed that the formed catalytic Cu-cystine nanoleaves (Cu-Cys NLs) possess a Cu(I)-Cu(II) electron transfer system similar to that in natural laccase. Reaction kinetic studies demonstrated that the catalyst follows the typical Michaelis-Menten model. Compared with natural laccase, the Cu-Cys NLs exhibit superior stability during long-term incubation under extreme pH, high-temperature or high-salt conditions. Remarkably, the Cu-Cys NLs could be easily recovered and still maintained 76% of their activity after 8 cycles. Finally, this laccase mimic was employed to develop a colorimetric method for epinephrine detection, which achieved a wider linear range (9–455 µmol·L−1) and lower limit of detection (2.7 µmol·L−1). The Cu-Cys NLs also displayed excellent specificity and sensitivity towards epinephrine in a test based on urine samples. [ABSTRACT FROM AUTHOR]

In the present study, graphene oxide (GO) nanosheets were functionalized with l-cystine (GO@Cystine), a natural and stable sulfur-containing amino acid, via a simple one-pot process. The synthesized adsorbent was used to selectively extract and concentrate mercury (Hg) ions from aqueous solutions before their determination by cold vapor atomic absorption spectrometry. To achieve maximum performance, key parameters affecting the extraction process were investigated and optimized. The results showed that 30 mg GO@Cystine was capable of extracting Hg ions at pH = 3.0, with an average efficiency of 96%. Due to the strong binding of Hg ions to the adsorbent surface, the quantitative elution with HCl solution was possible at concentrations above 5 mol L−1. The linear calibration curve in the concentration range of 0.1–10.0 ng mL−1 (r = 0.9974), the limit of detection of 13 ng L−1, and the relative standard deviations of 3.3% and 2.7% were achieved at 0.5 and 2.5 ng mL−1, respectively. The adsorbent capacity and the maximum preconcentration factor were 98.3 mg g−1 and 125, respectively. The proposed method was able to extract and measure mercury ions in aqueous environmental samples, such as river water and seawater. The extraction recoveries of the spiked standard solutions (2.5 ng mL−1) ranged from 94.8 to 97.2%. Therefore, along with other common adsorbents, the use of GO@Cystine as a highly potent, low-cost, simple, environmentally friendly, and selective adsorbent is recommended. [ABSTRACT FROM AUTHOR]

Abstract Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on l‐cystine produced using Pantoea ananatis NITE BP‐02525 when used as a nutritional additive (amino acid) or as a sensory additive (flavouring compound) in feed and water for drinking for all animal species. l‐Cystine is a dispensable sulfur‐containing amino acid, naturally occurring in proteins of plants and animals. The amino acid l‐cystine produced by fermentation with P. ananatis NITE BP‐02525 is safe for all animal species, if the requirements for sulfur‐containing amino acids are respected. The maximum amount of l‐cystine that can be safely added to the diet will depend on the levels of other sulfur amino acids. This conclusion would also cover its use as a sensory additive. The use of l‐cystine produced by fermentation with P. ananatis NITE BP‐02525 in animal nutrition raises no safety concerns to consumers of animal products. The additive under assessment is considered slightly irritating by inhalation, not irritating to the skin or eyes and is not a skin sensitiser. There is no risk for persons handling the additive from the exposure to endotoxins by inhalation. The use of the l‐cystine produced by fermentation with P. ananatis NITE BP‐02525 as a feed additive does not represent a risk to the environment. l‐Cystine is considered efficacious in partially meeting the requirements of sulfur‐containing amino acids in all animal species. For the supplemental l‐cystine to be as efficacious in ruminants as in non‐ruminant species, it would require protection against degradation in the rumen. It is also considered efficacious as a feed flavouring compound under the proposed conditions of use.

Saccharothrix algeriensis NRRL B-24137 is an actinobacterium isolated from Algerian Saharan soil. This strain has the ability to produce several dithiolopyrrolone antibiotic derivatives depending on the precursors added to the culture medium. This group of antibiotics is known for their potent antimicrobial and anticancer activities. Holomycin is a member of the dithiolopyrrolone group of antibiotics, and has already been isolated from several species of actinobacteria belonging to the genus Streptomyces and also from some Gram-negative bacteria. In this study, holomycin was produced for the first time in the culture broth of a non-Streptomyces actinobacteria. This antibiotic was induced by adding 5 mM of L-cystine as precursor to the semi-synthetic fermentation broth of Sa. algeriensis NRRL B-24137 and then fully identified after HPLC purification. The minimum inhibitory concentrations (MIC) of holomycin were determined against several pathogenic microorganisms, including Escherichia coli ATCC 10536 Klebsiella pneumoniae CIP 82.91, Listeria monocytogenes CIP 82110, Staphylococcus aureus CIP 7625, Aspergillus carbonarius M333, Fusarium culmorum FC1, Candida albicans IPA 200. This antibiotic showed a broad-spectrum antimicrobial activity, inhibiting a variety of Gram-positive and Gram-negative bacteria, and micro-fungi. [ABSTRACT FROM AUTHOR]

Previously we found that three components of a commonly used mammalian cell culture medium incorporated into agar killed cryptococci (Granger and Call 2019). The components were L- c ystine, i ron [Fe(III)], and p yridoxal (CIP). We now report on a buffered solution at neutral pH of the three components, which was highly fungicidal without agar. We showed that CIP fungicidal activity, identical to the findings with cell culture medium, was inactivated by visible light and was unstable with storage in the dark. Congeners replacing either pyridoxal or L-cystine in CIP revealed structural requirements for fungicidal activity. Replacing pyridoxal in CIP with 2-hydroxy-5-nitrobenzaldehyde produced a solution that was equally fungicidal and maintained fungicidal activity upon storage in the dark for up to 50 days. We employed methods for excluding iron from CIP and found that fungicidal activity was not affected. Upon mixing L-cystine and pyridoxal in buffer at pH 7.0, diode array spectroscopy revealed a red-shift of absorbance maximum from 391 nm to 398 nm. Our findings point to Schiff base reaction between the pyridoxal aldehyde group of C1 with the alpha amino group(s) of cystine to yield a fungicidal compound. Light at wave length approximately 400 nm inactivates this complex accompanied by bleaching of the pyridine ring of pyridoxal. Our findings may be useful for design of a class of fungicidal compounds formed through Schiff base reaction of disulfide compounds with aromatic ring-bearing aldehydes. [ABSTRACT FROM AUTHOR]

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on l‐cystine produced using Pantoea ananatis NITE BP‐02525 when used as a nutritional additive (amino acid) or as a sensory additive (flavouring compound) in feed and water for drinking for all animal species. l‐Cystine is a dispensable sulfur‐containing amino acid, naturally occurring in proteins of plants and animals. The amino acid l‐cystine produced by fermentation with P. ananatis NITE BP‐02525 is safe for all animal species, if the requirements for sulfur‐containing amino acids are respected. The maximum amount of l‐cystine that can be safely added to the diet will depend on the levels of other sulfur amino acids. This conclusion would also cover its use as a sensory additive. The use of l‐cystine produced by fermentation with P. ananatis NITE BP‐02525 in animal nutrition raises no safety concerns to consumers of animal products. The additive under assessment is considered slightly irritating by inhalation, not irritating to the skin or eyes and is not a skin sensitiser. There is no risk for persons handling the additive from the exposure to endotoxins by inhalation. The use of the l‐cystine produced by fermentation with P. ananatis NITE BP‐02525 as a feed additive does not represent a risk to the environment. l‐Cystine is considered efficacious in partially meeting the requirements of sulfur‐containing amino acids in all animal species. For the supplemental l‐cystine to be as efficacious in ruminants as in non‐ruminant species, it would require protection against degradation in the rumen. It is also considered efficacious as a feed flavouring compound under the proposed conditions of use. [ABSTRACT FROM AUTHOR]

Thanks to the characteristics of lightweight and high-efficiency in low-frequency, triboelectric nanogenerator (TENG) is considered a highly promising technology to effectively harvest human mechanical energy. However, the low output of wearable TENG significantly limits its application in self-powered wearable electronic systems. Herein, we propose a high-output multilayer-structured triboelectric nanogenerator (HM-TENG) fabricated by nylon/ L -cystine composite nanofiber film (NCNF), which can efficiently harvest various human bio-mechanical energy. Based on the excellent positive triboelectric performance of L -cystine and the corresponding preparation process research, the fabricated TENG by NCNF with 8 w% L -cystine achieves several times the output performance of TENG with pure nylon nanofiber. Besides, the fabricated HM-TENG obtain a high power density of 11.52 W/m2, which is 5–500 folds higher than previous related research work. Importantly, relied on the designed power management circuit and the installation of a foot mounted HM-TENG, various self-powered wearable electronic devices constructed by harvesting human bio-mechanical energy have been successfully demonstrated. Our research not only provides a novel method for developing high-output TENG but also offers a important solution for the design of self-powered electronic devices. [Display omitted] • It is found that L -cystine has better positive triboelectric performance than nylon through software simulation. • Fabricated by NCNF with 8 w% L -cystine, TENG achieves several times output performance of TENG with pure nylon nanofiber. • The power density of HM-TENG increased to 11.52 W/m−2, which is 1–2 orders of magnitude higher than previous similar studies. • HM-TENG with PMC can provides energy for sustainable operation of wearable electronics by harvesting bio-mechanical energy. [ABSTRACT FROM AUTHOR]

L-cystine (LC) was employed as an additive to inhibit crystallization of V(II) or V(III) specie in the negative electrolyte and extend the practical application of vanadium redox flow battery (VRFB) at below-ambient temperatures. UV-Vis spectrometry showed LC has no effect on the absorption in the range of 300-800 nm. Crossover testing indicated that LC can permeate from negative side to positive side across the membrane Nafion 117. Static thermal stability testing showed LC can significantly inhibit precipitation of V(II)~V(IV) ions or V(V) in 1.8 M vanadium electrolyte with 3.0 M H2SO4 at 5 or 50 °C. It is found that 2-4 wt% LC in vanadium electrolytes can lower viscosity compared to the blank electrolyte. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) show V(III) electrolyte with 2 wt% LC exhibits superior electrochemical activity and diffusion coefficient, compared with the pristine electrolyte. VRFB single-cell tests operating at 5 and 50 °C were investigated. LC can inhibit the capacity decay and voltage efficiency loss at below-ambient temperatures. VRFB with LC obtains better performance of higher capacity retention (93.14 vs. 92.21%) and energy efficiency (73.36 vs. 68.66%) than the pristine at 5 °C. [ABSTRACT FROM AUTHOR]

A more efficient, economical and environmentally friendly process which combines with organic synthesis, electrochemical reduction and electrodialysis technology to produce high quality N-acetyl-L-cysteine. [Display omitted] • A novel green process to produce high quality NAC was developed. • The NAC preparation process combines electrochemical synthesis with electrodialysis technology, using the carbon electrode. • The novel process improved production efficiency and reduced energy consumption and production cost. • The novel process significantly reduced the quantity of organic solvents consumption and wastes discharge, which is environmentally friendly. N-acetyl-L-cysteine (NAC) is widely used in the biochemistry, pharmaceuticals and food additives. At present, the synthesis methods of NAC are difficult to achieve high-quality NAC production due to multi-step separation, poor product quality and heavy pollution. In this study, a new green process was developed combined with organic synthesis, electrochemical reduction and electrodialysis technology to efficiently produce high quality NAC. This new process adopted the strategy of acylation followed by electrolysis. Firstly, L-cystine was acetylated to N, N'-diacetyl-L-cystine (DiNAC), and then DiNAC was electrochemically directly reduced to NAC using carbon cathode. Finally, the high quality NAC was extracted after desalting by electrodialysis. The novel preparation process avoids racemization and oxidation of intermediate products, achieves the removal of impurities, desalting and recycling of electrolyte, and largely reduces wastes discharge. The pilot scale test showed that the total yield was 73.1%, the electrochemical yield was 96.2%, and the energy consumption was 2.56 kW·h kg−1. The brief environmental and tech-economic analysis demonstrated that the process had the advantages of mild reaction conditions, short synthesis steps, high product quality, low waste emissions. It indicates that this novel process is efficient, economical, environmentally friendly, and suitable for the industrial production. [ABSTRACT FROM AUTHOR]

Cystine is a sulphur-containing amino acid formed from two molecules of cysteine. It is present in many proteins and detoxifies many harmful chemicals, protects against radiation and pollution and is useful in the treatment of rheumatoid arthritis. It assists in the supply of insulin to the pancreas, which is needed for assimilation of sugars and starch. Thallium(III) is used as a two-electron oxidant in acid medium. The oxidation of L-cystine by thallium(III) was studied in 3.0 mol dm-3 perchloric acid medium at 30oC and the unreacted thallium(III) was determined iodometrically. The reaction was found to be first order dependent on [thallium(III)] and fractional order dependent on [cystine]. Increase in [H+] was found to decrease the reaction rate. Thallium(I), one of the products, has negligible effect on the rate of the reaction. A plausible mechanism was proposed considering Tl(OH)2+ to be the reactive species and invoking complexation between the substrate and Tl(OH)2+. Thermodynamic parameters for the rate-determining step, energy of activation, Ea and entropy of activation, ΔS* were computed using linear least squares method. [ABSTRACT FROM AUTHOR]

Solubilities of L-cystine, L-tyrosine, and L-leucine in aqueous NaCl media at 298.15 K have been studied. Indispensable and related solvent parameters such as molar mass, molar volume, etc., were also determined. The results are used to evaluate the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy and dipole-dipole interaction effects during the course of solvation. Various weak interactions involving solute-solvent or solvent-solvent molecules were characterized in order to find their role on the solvation of these amino acids. [ABSTRACT FROM AUTHOR]

The aim of the present study was to determine the effect of reducing agents (Lcystine, glutathione and proteases) on wheat gluten recovery and quality characteristics of dough and cookies. PBW-343 and RAJ-3765 wheat varieties were analysed for physico-chemical properties which indicated that wheat variety RAJ-3765 had superior quality characteristics in comparison to PBW-343. Wet gluten and dry gluten %yields were reduced with addition of reducing agents. As the concentration of reducing agents increased gluten, yield decreased further. The dough strength (resistance to extension) decreased, whereas extension of dough increased significantly with the addition of reducing agents. Upon addition of reducing agents, spread factor increased, whereas hardness decreased. Glutathione was found to be the most effective reducing agent out of the three reducing agents used in this study.

Herein, we are described a green route to prepare reduced graphene oxide supported cobalt inorganic complex nanocomposite (GRGO/[Co(bpy)3]) (bpy=2,2′-bipyridine) through facile and wet chemical approach. The formation of the nanocomposite was confirmed through suitable physical and chemical characterization techniques. The GRGO/[Co(bpy)3] nanocomposite was coated on the pretreated glassy carbon electrode (GCE). The GCE/GRGO/[Co(bpy)3] modified electrode has excellent electrocatalytic ability towards methyl parathion reduction, while the overpotential drops drastically to -0.18 V (vs. Ag/AgCl). Moreover, the effect of concentration, scan rate and electrolyte pH were detail studied. Besides, the linear response range was 0.05-1700 μM and the detection limit was 0.0029 μM (S/N=3) and the sensitivity was 1.8197 μA μM−1 cm−2. Moreover, the fabricated electrode has high level of selectivity, which delivers satisfactory repeatability, reproducibility and stability. The sensing method was successfully demonstrated in real samples such as, tomato and apple samples. [ABSTRACT FROM AUTHOR]

The sulfur electric-field-gradient tensor for a disulfide bond in 33 S 2 -labeled L-cystine has been investigated by 33 S nuclear quadrupole resonance (NQR). 33 S 2 -labeled L-cystine is synthesized by introduction of disulfide ions prepared from elemental 33 S-sulfur into an amino acid derivative, the side chain of which is iodinated. In its NQR spectrum, sharp single peaks are observed at between 24.63 and 24.90 MHz in the temperature range from 80 to 298 K. The two-dimensional nutation echo 33 S NQR experiment is carried out at 160 K, and the quadrupole coupling constant, C Q , and the asymmetric parameter, η Q , are obtained to be 46.9(9) MHz and 0.6(1), respectively. The calculated 33 S electric-field-gradient tensor components with respect to the molecular frame is briefly discussed., (© 2023 John Wiley & Sons, Ltd.)

Smart polymer nanogel-assisted drug delivery systems have attracted more and more attention in cancer chemotherapy because of their well-defined morphologies and pleiotropic functions in recent years. In this work, an L-cystine-crosslinked reduction-responsive polypeptide nanogel of methoxy poly(ethylene glycol)-poly(L-phenylalanine-co-L-cystine) (mPEG-P(LP-co-LC)) was employed as a smart excipient for RM-1 prostate cancer (PCa) chemotherapy. Doxorubicin (DOX), as a regular chemotherapy drug, was embedded in the nanogel. The loading nanogel marked as NG/DOX was shown to exhibit glutathione (GSH)-induced swelling and GSH-accelerated DOX release. Subsequently, NG/DOX showed efficient cellular uptake and proliferation inhibition. Furthermore, NG/DOX presented enhanced antitumor efficacy and security in an RM-1 PCa-grafted mouse model in vivo, indicating its great potential for clinical treatment. [ABSTRACT FROM AUTHOR]

Cystinuria is a genetic disease marked by recurrent kidney stone formation, usually at a young age. It frequently leads to chronic kidney disease. Treatment options for cystinuria have been limited despite comprehensive understanding of its genetic pathophysiology. Currently available therapies suffer from either poor clinical adherence to the regimen or potentially serious adverse effects. Recently, we employed atomic force miscopy (AFM) to identify l-cystine dimethylester (CDME) as an effective molecular imposter of l-cystine, capable of inhibiting crystal growth in vitro. More recently, we demonstrated CDME's efficacy in inhibiting l-cystine crystal growth in vivo utilizing a murine model of cystinuria. The application of AFM to discover inhibitors of crystal growth through structural mimicry suggests a novel approach to preventing and treating crystal diseases. [ABSTRACT FROM AUTHOR]

L-cystine is a dispensable sulphur-containing amino acid, naturally occurring in proteins of plants and animals. L-cystine is safe for all animal species if the requirements for sulphur amino acids are respected. The maximum amount of L-cystine that can be safely added to the diet will depend on the levels of other sulphur-containing amino acids. Supplemental L-cystine will not be deposited in animal tissues as such: it will be incorporated in body proteins without causing any change in their natural composition or it will be metabolised and excreted. The product under application does not contain substances of toxicological concern. Thus, the use of L-cystine in animal nutrition does not raise any concerns for consumer safety. In the absence of any data, it would be prudent to consider L-cystine as irritant to skin, eyes and mucous membranes and as a potential dermal sensitiser. Therefore, it would be prudent to assume that exposure of skin, eyes and respiratory tract is hazardous. The use of the natural amino acid L-cystine as feed additive does not represent a risk to the environment. L-Cystine is considered efficacious in partially meeting the requirements for sulphur-containing amino acids in all animal species.

The present work reports the synthesis and evaluation of surface active properties of amino acid-based gemini surfactants, namely, sodium dilauraminocystine (SDLC) and sodium dimyristaminocystine (SDMC) derived from L-cystine and fatty acids. The effect of reaction variables like molar ratio of raw materials and temperature has been studied for the synthesis of these gemini surfactants. In preparation of these gemini surfactants, fatty acids (lauric/myristic) were reacted with thionyl chloride to obtain respective acid chlorides (lauroyl/myristoyl). These acid chlorides were further reacted with L-cystine at different reaction conditions to get amino acid based-gemini surfactants. The study revealed that 1:2.5 molar ratio of reactants, namely, L-cystine and lauroyl/myristoyl chloride and 10–15° reaction temperature resulted in maximum yield of amino acid-based gemini surfactants (SDLC and SDMC). Surface active properties of synthesized gemini surfactants (SDLC and SDMC) were also compared with their corresponding monomeric units, namely, sodium lauroyl cysteine (SLC) and sodium myristoyl cysteine (SMC), respectively. The results demonstrated that gemini surfactants (SDLC and SDMC) had better surface active properties than their corresponding monomeric units. The structures of synthesized amino acid-based gemini surfactants were also confirmed by FTIR,1H NMR,13C NMR, and ESI-MS spectral data. [ABSTRACT FROM AUTHOR]

The results of the kinetic measurements of Bi(III) electroreduction on a mercury electrode in 1–8 mol dm −3 chlorate (VII) solutions and in the presence of cystine demonstrate a dependence of the process on the temperature. The applied electrochemical techniques (DC polarography, cyclic and SWV voltammetry) allowed for the determination of the kinetic and thermodynamic parameters and their correlation with water activity. The catalytic activity of cystine was confirmed by the decrease in overall enthalpies of activation. The changes in the values of ΔH≠ and ΔS0 for Bi(III) electroreduction in the presence of cystine with the increase of chlorate (VII) concentration showed that the mechanism is different in solutions with low water activity as compared to those with high water activity. Probably it is connected with a different structure of the activated complexes (Bi-Hg(SR) 2), mediating electron transfer. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The adsorption and corrosion inhibition behavior of mild steel in 0.1 M H2SO4in presence of L-cystine and L-cystine in combination with surfactants sodium dodecyl sulfate and cetyltrimethyl ammonium bromide at 30–60°C was investigated using weight loss and potentiodynamic polarization measurements. Inhibition efficiency of L-cystine is synergistically enhanced on addition of surfactants. Surface morphology of corroded steel samples was evaluated using scanning electron microscopy and atomic force microscopy, which further confirmed the existence of an adsorbed protective film on the mild steel surface. Calculated thermodynamic parameters reveal that adsorption process is spontaneous and obey Langmuir adsorption isotherm. [ABSTRACT FROM AUTHOR]

The aim of the present study was to determine the effect of reducing agents (Lcystine, glutathione and proteases) on wheat gluten recovery and quality characteristics of dough and cookies. PBW-343 and RAJ-3765 wheat varieties were analysed for physico-chemical properties which indicated that wheat variety RAJ-3765 had superior quality characteristics in comparison to PBW-343. Wet gluten and dry gluten %yields were reduced with addition of reducing agents. As the concentration of reducing agents increased gluten, yield decreased further. The dough strength (resistance to extension) decreased, whereas extension of dough increased significantly with the addition of reducing agents. Upon addition of reducing agents, spread factor increased, whereas hardness decreased. Glutathione was found to be the most effective reducing agent out of the three reducing agents used in this study. [ABSTRACT FROM AUTHOR]

L-cystine is a dispensable sulphur-containing amino acid, naturally occurring in proteins of plants and animals. L-cystine is safe for all animal species if the requirements for sulphur amino acids are respected. The maximum amount of L-cystine that can be safely added to the diet will depend on the levels of other sulphur-containing amino acids. Supplemental L-cystine will not be deposited in animal tissues as such: it will be incorporated in body proteins without causing any change in their natural composition or it will be metabolised and excreted. The product under application does not contain substances of toxicological concern. Thus, the use of L-cystine in animal nutrition does not raise any concerns for consumer safety. In the absence of any data, it would be prudent to consider L-cystine as irritant to skin, eyes and mucous membranes and as a potential dermal sensitiser. Therefore, it would be prudent to assume that exposure of skin, eyes and respiratory tract is hazardous. The use of the natural amino acid L-cystine as feed additive does not represent a risk to the environment. L-Cystine is considered efficacious in partially meeting the requirements for sulphur-containing amino acids in all animal species. [ABSTRACT FROM AUTHOR]

Abstract: The results of kinetic measurements revealed an accelerating influence of cystine and water activity on multistep Bi(III) ion electroreduction in chlorates(VII). The magnitude of the catalytic effect of cystine was determined based on the obtained kinetic parameters, which were correlated with water activity. The multistep Bi(III) electroreduction process is controlled by the kinetics of the formation of active Bi–Hg(SR)2 complexes preceding the transfer of consecutive electrons. Cystine is a mediator in the formation of these complexes, which are located inside the adsorbate layer. A mechanism is proposed for the catalytic action of cystine on Bi(III) ion electroreduction in chlorate(VII) solutions. [Copyright &y& Elsevier]