L-cysteine Methyl Ester Hydrochloride Research Articles

Construction and Performance Study of a Dual-Network Hydrogel Dressing Mimicking Skin Pore Drainage for Photothermal Exudate Removal and On-Demand Dissolution.

In recent years, negative pressure wound dressings have garnered widespread attentions. However, it is challenging to drain the accumulated fluid under negative pressures for hydrogel dressings. To address this issue, this study prepared a chemical/physical duel-network PEG-CMCS/AG/MXene hydrogel composed by chemical disulfide crosslinked network of four-arm polyethylene glycol/carboxymethyl chitosan (4-Arm-PEG-SH/CMCS), and the physical network of hydrogen bond of agar (AG). Under near-infrared light (NIR) irradiation, the PEG-CMCS/AG/MXene hydrogel undergoes photothermal heating due to integrate of MXene, which destructs the hydrogen bond network and allows the removal of exudate through a mechanism mimicking the sweat gland-like effect of skin pores. The photothermal heating effect also enables the antimicrobial activity to prevent wound infections. The excellent electrical conductivity of PEG-CMCS/AG/MXene can promote cell proliferation under the external electrical stimulation (ES) in vitro. The animal experiments of full-thickness skin defect model further demonstrate its ability to accelerate wound healing. The conversion between thioester and thiol achieved with L-cysteine methyl ester hydrochloride (L-CME) can provides the on-demand dissolution of the dressing in situ. This study holds promises to provide a novel solution to the issue of fluid accumulations under hydrogel dressings and offers new approaches to alleviating or avoiding the significant secondary injuries caused by frequent dressing changes.

Characterization of L-cysteine methyl ester hydrochloride–stabilized gold nanoparticles

Characterization of L-cysteine methyl ester hydrochloride–stabilized gold nanoparticles

Anti-Inflammatory Actions of Expectorants in a Rat Carrageenan-Induced Footpad Edema Model.

S-Carboxymethyl-L-cysteine (SCMS) exhibits sputum-regulating and anti-inflammatory actions. Previous studies reported the anti-inflammatory effects of SCMS on chronic inflammatory diseases, but no study has examined these effects on acute inflammatory diseases. In this study, we investigated the anti-inflammatory effects of SCMS in a rat carrageenan-induced footpad edema model, which is routinely used as an acute inflammation model. Expectorants were administered to rats with footpad edema induced by subcutaneously administering 1%λ-carrageenan to the footpad of the left posterior limb, and the dose dependency of the anti-inflammatory effects was evaluated. As a result, even when the dose of SCMS was increased to 400 mg/kg, there were no inhibitory effects on edema. Furthermore, we examined the inhibitory effects of other expectorants (ambroxol hydrochloride, N-acetyl-L-cysteine, L-cysteine ethylester hydrochloride, and L-cysteine methylester hydrochloride), which were reported to exhibit anti-inflammatory effects on chronic inflammation, on edema. However, none of these expectorants inhibited edema.

Design, Synthesis, and Safener Activity of Novel Methyl (R)-N-Benzoyl/Dichloroacetyl-Thiazolidine-4-Carboxylates.

A series of novel methyl (R)-N-benzoyl/dichloroacetyl-thiazolidine-4-carboxylates were designed by active substructure combination. The title compounds were synthesized using a one-pot route from l-cysteine methyl ester hydrochloride, acyl chloride, and ketones. All compounds were characterized by IR, 1H NMR, 13C NMR, and HRMS. The structure of 4q was determined by X-ray crystallography. The biological tests showed that the title compounds protected maize from chlorimuron-ethyl injury to some extent. The ALS activity assay showed that the title compounds increased the ALS activity of maize inhibited by chlorimuron-ethyl. Molecular docking modeling demonstrated that Compound 4e competed against chlorimuron-ethyl to combine with the herbicide target enzyme active site, causing the herbicide to be ineffective.

In Vitro Antifungal Activity of Cysteine Derivatives and their Combinations with Antifungal Agents Against Clinically Relevant Scedosporium species

Background: Members of the genus Scedosporium are emerging human pathogens, causing a wide range of infections. Their treatment means a challenge for clinicians, mostly because of the low susceptibility of these causative agents to conventional antifungal drugs. New alternative therapeutic approaches are required for better clinical outcomes. Cysteine and its derivatives alone or in combinations with antifungal drugs might have improved antifungal effects against Scedosporium species. Methods: The in vitro antifungal effects of two cysteine forms and three of their derivatives (i.e., D-cysteine, L-cysteine, L-cysteine-methyl ester hydrochloride, N-isobutyryl-D-cysteine, and N-isobutyryl-L-cysteine) were determined using the CLSI M38-A2 broth microdilution method. The in vitro drug interactions between the most effective cysteine derivatives and some conventional antifungal drugs were also investigated using checkerboard assays in case of four clinical isolates. Results: L-cysteine-methyl ester hydrochloride proved to be the most effective among the investigated compounds. N-isobutyryl-L-cysteine exhibited antifungal activity against one Scedosporium aurantiacum strain only. D-cysteine, L-cysteine and N-isobutyryl-D-cysteine proved to be ineffective against Scedosporium spp. in the investigated concentration range. No significant differences were found in the susceptibilities between environmental and clinical isolates. L-cysteine-methyl ester hydrochloride could interact synergistically with amphotericin B, caspofungin, terbinafine and voriconazole. Antagonistic interactions were not observed between the investigated compounds. Conclusions: The present study provides an evidence for the in vitro antifungal activity of L-cysteinemethyl ester hydrochloride and the synergistic interactions between this cysteine derivative and conventional antifungal agents. Based on our results, L-cysteine-methyl ester hydrochloride in combination with antifungal drugs could be applicable in the treatment of human Scedosporium infections in the future. However, further studies are required to clarify the antifungal mechanism of L-cysteine-methyl ester hydrochloride and to investigate its activity in vivo.

Hemicucurbiturils as receptors in extraction and transport of some amino acids

The molecular recognition properties of hemicucurbit[6]uril (HemiCB[6]) and hemicucurbit[12]uril (HemiCB[12]) towards a series of amino acid native and methyl esters (L-phenylalanine, L-leucine, L-valine, L-cysteine, L-tryptophan, L-isoleucine, L-phenylalanine methyl ester hydrochloride (L-PheOMe), L-tyrosine methyl ester hydrochloride (L-TyrOMe), L-valine methyl ester hydrochloride (L-ValOMe), L-leucine methyl ester hydrochloride (L-LeuOMe), L-serine methyl ester hydrochloride (L-SerOMe) and L-cysteine methyl ester hydrochloride (L-CysOMe) were investigated. In this respect, by means of liquid–liquid extraction, a series of amino acid native and methyl esters were extracted from an aqueous phase (pH = 5.5) into a chloroform phase as ion pairs in the presence of tropaeolin 00 as counterion. Based on results obtained in extraction experiments, the active transport assisted by pH gradient of amino acids as ion pairs through chloroform liquid membrane employing HemiCB[6] as carrier was performed. Both receptors used in experiments exhibited extractability towards amino acids under study. From the results obtained, one can observed the good affinity of both receptors, hemiCB[6, 12], towards hydrophobic amino acids (L-PheOMe, L-LeuOMe and L-ValOMe)). It was emphasised that the structure of hemicucurbiturils and amino acids together with the anion nature, and pH have influenced the experimental results.

Total synthesis of pro-resolving and tissue-regenerative Protectin sulfido-conjugates

The stereospecific total synthesis of the pro-resolving and tissue-regenerative Protectin sulfido-conjugates: 16R,17S-PCTR1, 16R,17S-PCTR2, and 16R,17S-PCTR3, derived from docosahexaenoic acid, has been achieved. The key intermediate 16S,17S-epoxy-Protectin methyl ester was synthesized using the Sharpless catalytic asymmetric epoxidation to generate the chiral centers at C16 and C17. A Cs2CO3 promoted coupling provided the skipped diyne intermediate. Wittig reactions and epoxide opening with glutathione, l-cysteinylglycine, and l-cysteine methyl ester hydrochloride, respectively, were the key steps in the synthesis.

Evaluation of the physicochemical properties and the biocompatibility of polyethylene glycol-conjugated gold nanoparticles: A formulation strategy for siRNA delivery

The potential of RNA interference (RNAi)-based therapeutics for cancer has received much attention; however, delivery of RNAi effectors, such as small interfering RNA (siRNA), remains an obstacle to clinical translation. Non-viral delivery vectors have been used extensively to enhance siRNA delivery. Recently, the potential of gold nanoparticles (AuNPs) for transporting drugs, proteins and genetic materials has been demonstrated. Previously, our laboratory synthesised positively charged, surfactant-free AuNPs in water by the reduction of gold (III) chloride (AuCl3) using hydroxylamine hydrochloride (NH2OH·HCl) in the presence of l-cysteine methyl ester hydrochloride (HSCH2CH(NH2)COOCH3·HCl) as a capping agent. These AuNPs, which achieve higher cell viability in comparison to cetyl trimethyl ammonium bromide (CTAB, a surfactant)-capped counterparts, have demonstrated potential for siRNA delivery. However, it is well known that systemic administration of cationic delivery systems without biological stablising moieties causes non-specific binding with negatively charged serum proteins, resulting in particle aggregation and opsonisation. Consequently, highly stable AuNPs capped with l-cysteine methyl ester hydrochloride conjugated to poly(ethylene glycol) (PEG) were synthesised in this study. PEGylation enhanced the biocompatibility of the AuNPs by reducing toxicity in a range of cell types, by inhibiting interaction with serum proteins thus avoiding aggregation, and, by providing protection against degradation by nucleases. Moreover, these PEGylated AuNPs formed nanoparticles (NPs) with siRNA (which was first compacted with protamine), and had a diameter within the nanoscale range (∼250nm) and a near neutral surface charge (∼10mV). In the future a bifunctional PEG chain on the AuNPs (i.e., SH-PEG-NH2, SH-PEG-COOH) will be used to facilitate conjugation of a targeting ligand to enhance cell specific uptake.

First total synthesis of pro-resolving and tissue-regenerative Maresin sulfido-conjugates

The first stereospecific total synthesis of the pro-resolving and tissue-regenerative Maresin sulfido-conjugates: 13R,14S-MCTR1, 13R,14S-MCTR2 and 13R,14S-MCTR3, derived from docosahexaenoic acid, has been achieved. The key intermediate 13S,14S-epoxy-Maresin methyl ester was synthesized using a chiral pool strategy starting from 2-deoxy-d-ribose. Wittig reactions, selective epoxide formation and epoxide opening with glutathione, l-cysteinylglycine and l-cysteine methyl ester hydrochloride respectively, were the key steps in the synthesis.

Synthesis of L-Cysteine grafted nanoporous carbon (CMK-3) and its use as a new cadmium sorbent

Mesoporous silica SBA-15 synthesized by hydrothermal method has been used as template silica and sucrose as the carbon source, in preparation of CMK-3. This was carboxylated by ammonium persulfate ((NH4)2S2O8) and H2SO4, and functionalized with L-Cysteine methyl ester hydrochloride. The resulting samples were characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and Nitrogen adsorption–desorption measurements (BET). The functionalized product shows the BET surface area of 548.4m2g−1 and pore diameter 26.1Å. Cadmium sorption conditions such as the pH value, contact time, adsorbent dose, in batch system have been optimized. Under the experimental conditions, the adsorption capacity for cadmium has been 198mgg−1. The increment in the Cd(II) adsorption capacity of CMK-3 functionalized with L-Cysteine is attributed to the oxygenous and thiols functional groups formed on the surface of CMK-3 which can react with Cd(II).

Study of a cysteine derivative as a corrosion inhibitor for carbon steel in phosphoric acid solution

Inhibition of corrosion of carbon steel in phosphoric acid solution by use of l-cysteine methyl ester hydrochloride has been investigated by measurement of weight loss and use of electrochemical methods. The efficiency of inhibition was increased by increasing the concentration of the inhibitor and reduced by increasing the temperature. Polarization studies revealed that this compound behaves as mixed-type inhibitor. Electrochemical impedance spectroscopy showed that dissolution of the steel occurs as a result of charge-transfer. Adsorption of the inhibitor obeyed the Langmuir adsorption isotherm. Kinetic and thermodynamic data were calculated and are discussed.

Temperature Effect, Activation Energies and Thermodynamic Adsorption Studies of L-Cysteine Methyl Ester Hydrochloride As Copper Corrosion Inhibitor In Nitric Acid 2M

Temperature Effect, Activation Energies and Thermodynamic Adsorption Studies of L-Cysteine Methyl Ester Hydrochloride As Copper Corrosion Inhibitor In Nitric Acid 2M

Surface-Enhanced Raman Scattering Spectroscopy of Explosive 2,4-Dinitroanisole using Modified Silver Nanoparticles

2,4-Dinitroanisole (DNAN) is being used as a replacement for 2,4,6-trinitrotoluene (TNT) as a less-sensitive melt-cast medium explosive than TNT. In this paper, we studied the surface-enhanced Raman spectroscopy (SERS) analysis of DNAN using Ag nanoparticles (AgNPs) modified by L-cysteine methyl ester hydrochloride. Due to the formation of a Meisenheimer complex between DNAN and the modifier, the modified AgNPs can detect 20 μg/L (0.2 ng) and 0.1 mg/L (1 ng) DNAN in deionized water and aged tap water, respectively. Three other chemicals (L-cysteine, N-acetyl-L-cysteine, and L-cysteine ethyl ester hydrochloride) were used as AgNPs modifiers to study the mechanism of the SERS of DNAN. It was confirmed that the amino group of L-cysteine methyl ester hydrochloride was the active group and that the methyl ester group significantly contributed to the high SERS sensitivity of DNAN. In order to further test the mechanism of Meisenheimer complex formation, the effect of anions and cations present in natural water on the SERS of DNAN was studied. It was found that CO(3)(2-), Cl(-), and K(+) at 100 mg/L did not negatively affect the SERS of 10 mg/L DNAN, while SO(4)(2-), Na(+), Mg(2+), and Ca(2+) at 100 mg/L significantly quenched the SERS of 10 mg/L DNAN. The negative effect of the bivalent cations could be offset by SO(4)(2-).

Optical Activity and Chiral Memory of Thiol-Capped CdTe Nanocrystals

CdTe nanocrystals (NCs) passivated with chiral ligands d- and l-cysteinemethylester hydrochloride were prepared and observed to exhibit characteristic CD profiles with symmetrical mirror images depending on the chirality of the capping ligand. The optical activity of CdTe NCs is shown to originate from the distorted CdS shell including chiral capping molecules. The chirality of the NC surface is maintained even after ligand exchange with an achiral thiol, providing an unprecedented chiral memory effect.

Synthesis, Docking and Anti-Tumor Activity of β-L-1,3-Thiazolidine Pyrimidine Nucleoside Analogues

In the search for effective, selective, and nontoxic antiviral and antitumor agents, a variety of strategies have been devised to design nucleoside analogues. Here we have described the versatile synthesis of beta-L-1,3-thiazolidine nucleoside analogues. These analogues are all derived from the key stereochemically defined intermediate N-tert-butoxy-carbonyl-4-hydroxymethyl-1,3-thiazolidine-2-ol which was accessible in 57% yield starting from L-Cysteine methylester hydrochloride. N-tert-butoxycarbonyl-2-acyloxy-4-trityloxymethyl-1,3-thiazolidine was coupled with the pyrimidine bases in the presence of Lewis acids stannic chloride or trimethyl silyl triflate following Vorbruggen procedure. Proof of the structure and configuration was obtained through (1)H NMR, (13)C NMR, Mass, elemental analysis and NOE experiments. Docking and antitumor activity of these nucleoside analogues are also reported.

High-Field Chlorine NMR Spectroscopy of Solid Organic Hydrochloride Salts: A Sensitive Probe of Hydrogen Bonding Environment

A series of organic hydrochloride salts has been investigated using solid-state 35Cl and 37Cl NMR spectroscopy at applied magnetic field strengths of 9.4 and 18.8 T. Magic-angle spinning, static Hahn-echo, and quadrupolar Carr−Purcell Meiboom−Gill (QCPMG) echo experiments have been applied to investigate the chlorine electric field gradient (EFG) and chemical shift (CS) tensors for l-tyrosine hydrochloride, l-cysteine methyl ester hydrochloride, l-cysteine ethyl ester hydrochloride, quinuclidine hydrochloride, and tris sarcosine calcium chloride. Chlorine-35 nuclear quadrupolar coupling constants for these compounds range from 2.23 to 5.25 MHz, and isotropic chemical shifts range from approximately 9 to 53 ppm relative to the chloride ion in aqueous solution. The results demonstrate the feasibility and benefits of high-field 35/37Cl NMR studies of organic chloride salts. A discussion of the data in the context of the known X-ray or neutron diffraction structures for these compounds suggests that the chlor...

Mercury(II) Complexes of L-Cysteine Methyl Ester

The mercurial complexation of L-cysteine methyl ester hydrochloride with mercury(II) nitrate, chloride, and acetate has been investigated at low pH. Bis(methyl L-cysteineato)mercury(II) hydrochloride hydronitrate monohydrate, following isolation and extensive characterization, was shown to be the substance reported in the literature as the dihydrochloride sesquihydrate complex. The preparation and properties of bis(methyl L-cysteineato)mercury(II) dihydrochloride monohydrate are reported for the first time. The properties and structural features of the complexes are discussed mainly in the context of investigations utilizing infrared, 1H- and 13C-n.m.r. spectroscopy.

Effect of the Structure of Some Mercaptans on Their Amperometric Titration with Silver Nitrate

Summary The mercaptans studied were l-cysteine hydrochloride, dl-homocysteine thiolactone hydrochloride, s-methyl-l-cysteine, thioglycolic amide, N-acetyl-dl-penicillamine, N-acetyl-dl-homocysteine thiolactone, l-cysteine methyl ester hydrochloride, 2-mercaptoethylamine hydrochloride, dl-penicillamine hydrochloride, α -toluenethiol, and sodium thioglycolate. These mercaptans yielded theoretical titrations with silver nitrate, except cysteine hydrochloride and penicillamine, which were about 25% too high in titer. Cysteine has three ionized forms whereby the carboxyl group is completely ionized at the pH of the amperometric titration, while at pH 11 or higher, the −SRNHNO 2 form predominates, but at pH 9.0 it is negligible and the −SRNH + 3 form predominates. Ultra-violet absorption analyses indicated that silver ions react not only with the -SH groups, but at some other site in the molecule, probably involving the ionic forms, −SRNH + 3 , −SRNH 2 , and complex formation.