Thiol Compounds Research Articles

Synthesis of α‐1,3‐ and β‐1,3‐glucan esters with carbon–carbon double bonds and their surface modification

Abstractα‐1,3‐glucan and β‐1,3‐glucan esters with carbon–carbon double bonds (C=C), namely, α‐1,3‐glucan butenoate (α13GB) and β‐1,3‐glucan butenoate (β13GB), were synthesized from 3‐butenoic acid and trifluoroacetic anhydride. NMR analysis of the two esters revealed that the 3‐butenoyl groups were partially transformed to 2‐butenoyl groups. The total degree of substitution (DStotal) of the esters was calculated to be 3.0. According to gel permeation chromatography analysis, α13GB had a molecular weight (Mw) of 2.2 × 105 and β13GB had an Mw of 11.0 × 105, which was unexpectedly higher than that of the original glucan. This suggests that the β13GB chains were partially and intramolecularly crosslinked via the C=C bond. The α13GB and β13GB obtained had thermal degradation temperatures of 398 and 375 °C, respectively, and glass transition temperatures of 117 and 119 °C, respectively, which were higher than those of the corresponding saturated glucan butyrates. The surfaces of cast films of the esters were modified with 1H,1H,2H,2H‐perfluorodecanethiol, n‐dodecyl mercaptan or 3‐mercapto‐1,2‐propanediol via thiol‐ene reactions. Attenuated total reflection Fourier transform infrared spectroscopy and scanning electron microscopy energy‐dispersive X‐ray spectroscopy analyses revealed that the surface of α13GB was more successfully modified with these thiol compounds than that of β13GB. The water contact angle of the surface of each cast film was measured to evaluate its hydrophobicity and hydrophilicity, and indicated the successful surface modification of the film by the thiol compounds © 2020 Society of Chemical Industry

Reduced Thiol Compounds – Induced Biosensing, Bioimaging Analysis and Targeted Delivery

Reduced thiol compounds (RTCs), such as glutathione (GSH), cysteine (Cys), and homocysteine (Hcy), are important components of many amino acids and proteins. They are also basic building blocks that make up organisms and play an important role in physiology and pathology. Therefore, based on the fundamental characteristics of RTCs in vivo, researchers have reported their use in biosensing and imaging analysis and as carriers in life sciences and health sciences. In this review, we will introduce the principles of RTCs and highlight their applications in biosensing and imaging analysis and as carriers reported from 2015 to 2020.

Thiol-Bromo Click Reaction for One-Pot Synthesis of Star-Shaped Polymers.

Star-shaped polymers have unique physical properties and they are sought after materials in industry. However, the ease of synthesis is essential for translation of these materials into large-scale applications. Herein, a highly efficient synthetic method to prepare star-shaped polymers by combination of Cu-mediated reversible deactivation radical polymerization (Cu-RDRP) and thiol-bromo click reaction is described. Well-defined linear and block polymers with a very high bromine chain end fidelity are obtained via Cu-RDRP and subsequently react with multi-functional thiol compounds. High coupling efficiencies of larger than 90% are obtained owing to the quick and efficient reaction between thiols and alkyl bromides. Moreover, the arms of the obtained star-shaped polymers are linked via thioether bonds to the core, making them susceptible for oxidative degradation.

Surface spraying of anthocyanin through antioxidant defense and subcellular sequestration to decrease Cd accumulation in rice (Oryza sativa L.) grains in a lead-zinc mine area.

As an important class of flavonoids, anthocyanin has been used to enhance plant-defensive mechanisms against heavy metal stress. However, there are few available reports regarding surface spraying of anthocyanin for reduction of Cd poisoning in rice and its practical applications in paddy fields. After rice growing, measurements were taken of rice growth, pigments, the antioxidant system, thiol compounds, and distribution of Cd in rice tissues. The results showed that surface spraying anthocyanin could promote rice growth, and relative to the control, total chlorophyll significantly increased by 22.62% after surface spraying of 7.5gL-1 anthocyanin. Simultaneously, Cd accumulation in rice grains was 0.17 ± 0.02mgkg-1, which was significantly decreased by 46.88% relative to the control. In the pot experiment (40-day-old rice), treatment with 7.5gL-1 anthocyanin resulted in decreases of ·O2-, H2O2, and malondialdehyde contents in rice leaves, while the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were increased by 59.10, 23.81, 41.75, and 9.39%, respectively. Meanwhile, contents of glutathione, ascorbic acid, non-protein thiols, and phytochelatins showed respective increases of 7.24, 14.49, 42.81, and 41.13% compared with the control value. Subcellular analysis revealed that surface spraying of anthocyanin increased organelle and soluble fractions of Cd in leaf cells. In conclusion, surface spraying of 7.5gL-1 anthocyanin was mainly attributed to increased antioxidant activities and subcellular sequestration of Cd in organelles and soluble fractions in rice leaves to reduce Cd accumulation in rice grains in the field.

Effects of Exogenous Organic Acids on Cd Tolerance Mechanism of Salix variegata Franch. Under Cd Stress.

Chelate induction of organic acids has been recognized to enhance metal uptake and translocation in plants, but the underlying mechanism remains unclear. In this study, seedlings of Salix variegata were hydroponically exposed to the combinations of Cd (0 and 50 μM) and three exogenous organic acids (100 μM of citric, tartaric, or malic acid). Plant biomass, antioxidant enzymes, non-protein thiol compounds (NPT) content, and the expression of candidate genes associated with Cd accumulation and tolerance were determined. Results showed that Cd significantly inhibited plant biomass but stimulated the activity of antioxidant enzymes in the roots and leaves, while the lipid peroxidation increased as well. Respective addition of three organic acids greatly enhanced plant resistance to oxidative stress and reduced the lipid peroxidation induced by Cd, with the effect of malic acid showing greatest. The addition of organic acids also significantly increased the content of glutathione in the root, further improving the antioxidant capacity and potential of phytochelatin biosynthesis. Moreover, Cd induced the expression level of candidate genes in roots of S. variegata. The addition of three organic acids not only promoted the expression of candidate genes but also drastically increased Cd accumulation in S. variegata. In summary, application of citric, tartaric, or malic acid alleviated Cd-imposed toxicity through the boost of enzymatic and non-enzymatic antioxidants and candidate gene expression, while their effects on Cd tolerance and accumulation of S. variegata differed.

Pd (II) Immobilized on Clinoptilolite as a Highly Active Heterogeneous Catalyst for Ullmann Coupling-type S-arylation of Thiols with Aryl Halides.

There are a number of protocols for Ullmann coupling-type S-arylation reactions, many of them suffer from the use of homogenous and often corrosive catalyst, cumbersome workup procedures, and long reaction times. Besides, many of these reagents are expensive and non-recoverable, leading to the generation of a large amount of toxic waste particularly when large-scale applications are considered. The aim of this study was to prepare a new Pd catalyst bonded on the surface of zeolite as a heterogeneous catalyst. A heterogeneous palladium catalyst has been prepared by immobilizing Pd ions on Clinoptilolite. This novel developed heterogeneous catalyst was thoroughly examined for Ullmann coupling-type S-arylation reaction using different bases, solvents and 0.003 mg of the catalyst. The structural and morphological characterizations of the catalyst were carried out using XRD, TGA, BET and TEM techniques. Highly efficient heterogeneous palladium catalyst has been developed by immobilizing Pd ions on Clinoptilolite, as one of the most abundant naturally occurring zeolites for Ullmann Sarylation. By using this method, we provide an efficient way to a wide variety of substituted thiolic compounds. Moreover, the catalyst is easily recovered using simple filtration and reused for 5 consecutive runs. In this effort, we developed a new Pd catalyst bonded on the surface of zeolite as a substrate to prepare the heterogeneous catalyst. We demonstrate that this novel catalyst offers reliable and convincing data that may offer a valuable application in further developing the science and technology of Ullmann reaction protocols and allied industries. Additionally, the catalyst was reusable and kept its high activities over a number of cycles.

Methylmercury formation in boreal wetlands in relation to chemical speciation of mercury(II) and concentration of low molecular mass thiols

Methylmercury (MeHg) is a neurotoxin formed from inorganic divalent mercury (HgII) via microbial methylation, and boreal wetlands have been identified as major sources of MeHg. There is however a lack of studies investigating the relationship between the chemical speciation of HgII and MeHg formation in such environments, in particular regarding to role of thiol compounds. We determined HgII methylation potentials, kmeth, in boreal wetland soils using two HgII isotope tracers: 198Hg(OH)2(aq) and HgII bonded to thiol groups in natural organic matter, 200HgII–NOM(ads), representing HgII sources with high and low availability for methylation. The 198Hg(OH)2(aq) tracer was consistently methylated to a 5-fold higher extent than 200HgII–NOM(ads), independent of environmental conditions. This suggests that the concentration of HgII in porewater was a decisive factor for HgII methylation. A comprehensive thermodynamic speciation model (including HgII complexes with inorganic sulfide (H2S), polysulfides (H2Sn), thiols associated with natural organic matter (NOM–RSH) and specific low molecular mass thiols (LMM–RSH) provided new insights on the speciation of HgII in boreal wetland porewaters, but did not demonstrate any clear relationship between kmeth and the calculated chemical speciation. In contrast, significant positive relationships were observed between kmeth and the sum of LMM thiol compounds of biological origin. We suggest two possible mechanisms underlying these correlations: 1) LMM thiols kinetically control the size and composition of the HgII pool available for microbial uptake, and/or 2) LMM thiols are produced by microbes such that the correlation reflects a relation between microbial activity and MeHg formation.

Aluminum-Based Initiators from Thiols for Epoxide Polymerizations

We present a new method for epoxide polymerizations utilizing aluminum-based initiators, which leverage the chemical versatility of thiol compounds to control the polymer end group. The homo- and c...

Transcriptomic analyses reveal the pathways associated with the volatilization and resistance of mercury(II) in the fungus Lecythophora sp. DC-F1

The biotic enzymatic reduction of mercury II [Hg(II)] to elemental Hg [Hg(0)] is an important pathway for Hg detoxification in natural ecosystems. However, the mechanisms of Hg(II) volatilization and resistance in fungi have not been understood completely. In the present study, we investigated the mechanisms of Hg(II) volatilization and resistance in the fungus Lecythophora sp. DC-F1. Hg(II) volatilization occurred during the investigation via the reduction of Hg(II) to Hg(0) in DC-F1. Comparative transcriptome analyses of DC-F1 revealed 3439 differentially expressed genes under 10 mg/L Hg(II) stress, among which 2770 were up-regulated and 669 were down-regulated. Functional enrichment analyses of genes and pathways further suggested that the Hg(II) resistance of DC-F1 is a multisystem collaborative process with three important transcriptional responses to Hg(II) stress: a mer-mediated Hg detoxification system, a thiol compound metabolism, and a cell reactive oxygen species stress response system. The phylogenetic analysis of merA protein homologs suggests that the Hg(II) reduction by merA is widely distributed in fungi. Overall, this study provides evidence for the reduction of Hg(II) to Hg(0) in fungi via the mer-mediated Hg detoxification system and offers a comprehensive explanation for its role within Hg biogeochemical cycling. These findings offer a strong theoretical basis for the application of fungi in the bioremediation of Hg-contaminated envionments.

An aggregation-induced emission fluorogen/DNA probe carrying an endosome escaping pass for tracking reduced thiol compounds in cells.

The fluorescent nanoprobes for reduced thiol compounds (represented by glutathione, GSH) are constructed based on the aggregation-induced emission (AIE) luminescence mechanism and endosome escape technology. First, a DNA sequence was designed with the decoration of biotin at the 5'-end, disulfide bound in the internal portion, and amino at the 3'-end. The aptamer of the MCF-7 cell was also one of the most important structures in our DNA sequence for the selectivity of MCF-7 cells. We modified streptavidin-modified magnetic beads (MB) with biotin-modified influenza virus hemagglutinin peptide (HA) and biotin-DNA-amino to form MB/DNA/HA. Carboxyl-modified tetraphenylethylene (TPE), an iconic AIE fluorogen, was bonded with amino-modified DNA by covalent interactions (TPE/DNA). Then, the TPE molecule was attached on the outer layer of MB via biotin-modified TPE/DNA to form MB/DNA/HA/TPE. Compared with traditional AIE/biomolecule conjugates, the nanoprobe had an enhanced endosome escape function, due to the assembly of HA. This construction made the intracellular fluorescence response more accurate. In the presence of reduced thiol compounds (take GSH, for example), the disulfide bond on the DNA was reduced by thiol-disulfide exchange reactions and the TPE molecule was released into the solution. The shedding TPE molecule was more hydrophobic than TPE/DNA and the conversion of TPE/DNA to shedding TPE could lead to the aggregation of the TPE fluorogen. Thus, its fluorescence was enhanced. Under the optimized condition, the fluorescence intensity increased with the increase in concentration of GSH' ranging from 1.0 × 10-9M to 1.0 × 10-5M' and the detection limit was 1.0 × 10-9M. The relative standard deviation (RSD) was calculated to be 3.6%. The recovery in cell homogenate was from 94.5 to 102.7%. The nanoprobe provided a way for the detection of reduced thiol compounds in MCF-7 cells. We envision that, in the near future, our strategy of DNA-instructed AIE could be widely applied for biosensing and bioimaging in vitro and even in vivo with dramatically enhanced sensitivity. Graphical Abstract.

Evaluation of the changes in exposure to thiol compounds in chronic kidney disease patients using the PBPK model

Targeted covalent inhibitors designed to bind covalently to a specific molecular target have recently been a focus of drug development. Among these inhibitors, thiol compounds bind covalently to endogenous thiols in the body through a process involving disulfide bonds. We investigated the predictability of changes in the exposure to captopril, tiopronin, the active form of dalcetrapib and the active metabolite of prasugrel, R-138727, all of which have a sulfhydryl group, in moderate and severe chronic kidney disease (CKD) patients using a constructed PBPK model. The changes in the exposure to captopril, tiopronin and the active form of dalcetrapib under CKD conditions were well predicted. However, the change in exposure to R-138727, which is a secondary metabolite of prasugrel, was overpredicted. Although these thiol compounds covalently bind to endogenous thiols, our study concluded that changes in exposure to these compounds under CKD conditions can probably be predicted, except for compounds with a complicated mechanism whereby the thiol metabolite is generated.

Cellulose-Based Superhydrophobic Surface Decorated with Functional Groups Showing Distinct Wetting Abilities to Manipulate Water Harvesting.

Inspired by the distinct functions of desert beetles with efficient droplet nucleation and lotus leaves with excellent droplet removal, an integrated method is presented for the design of a superhydrophobic surface decorated with hydrophilic groups that can efficiently nucleate and remove water droplets. We constructed a cellulose-based superhydrophobic surface containing numerous olefin terminal groups by solvent exchange and spray coating. This surface is different from most of the reported biomimicking water harvesting surfaces that rely on complicated lithography and micropatterning techniques requiring special instruments. The obtained superhydrophobic surface was further modified using various thiol compounds via a thiol-ene reaction to manipulate the water harvesting property. The modified surfaces containing hydrophobic groups (e.g., 1-octadecanethiol and 1H,1H,2H,2H-perfluorodecanethiol) or a strong hydrophilic group (e.g., 3-mercaptopropionic acid and 6-mercapto-1-hexanol) exhibited insufficient fog collecting abilities due to poor water droplet nucleation or strong water adhesion. By contrast, the modified surface decorated with moderately hydrophilic amino groups combines the advantages of biological surfaces with distinct wetting features (such as fog-harvesting beetles and water-repellent lotus leaves), resulting in accelerated water nucleation and less compromise of the water removal efficiency. Molecular dynamic simulations revealed that the efficient droplet nucleation is attributed to the hydrophilic amino groups whereas the rapid droplet removal is due to the maintained superhydrophobicity of the amino group-modified surface. This strategy of decorating a superhydrophobic surface with moderately hydrophilic functional groups provides insight into the manipulation of droplet nucleation and removal for water collection efficiency.

Assessment of low intensivities γ-irradiation chronic influence on the state of thiol-disulphide exchange in the small intestine of rats

Today considerable attention is paid to the effects of ionizing radiation.chronic exposure in low doses and intensivity to humans and other bio-objects. The changes in the structural characteristics of the genome, nuclear, microsomal, mitochondrial, plasma membranes, cell proliferation, and the processes underlying radioresistance / radiosensitivity caused by irradiation have been experimentally studied. prolonged exposure to ionizing rays in small doses gradually causes a decrease in the endogenous reserve of thiol-dependent systems, and their complete depletion, which negatively affects the body's resistance to adverse environmental factors. There is a possibility of disturbances in the synthesis of thiol disulfide high molecular weight components. The objective: to study the state of thiol disulfide, glutathione redox system and acetylcholinesterase activity in the small intestine of rats of different sexes and ages under physiological conditions and under conditions of prolonged γ-irradiation in a total dose of 0.75 and 1.0 Gy. Results. It has been established that in a small bowel of intact mature rats after prolonged total γ-irradiation with a dose of 1.0 Gy, there were quite significant changes in the content of thiol compounds in the tissues of the small intestine. It was found that the content of SH-groups of protein origin in the tissues of the small intestine decreased relative to the age of control group animals by 28.8% and at the same time was lower than the value of males of the previous stage by 32.8%. The number of disulfide groups of protein origin in the small intestine of males three months after irradiation at a total dose of 1.0 Gy, relative to the same age control group animals, was 85.6% and at the same time was lower than the previous stage by 31.8%. Conclusions: 1.Under physiological conditions there are clear gender and age differences in the functional state of thiol-disulfide, glutathione redox system and acetylcholinesterase activity.Prolonged total γ-irradiation in the total dose of 0.75 and 1.0 Gy causes quite stable and profound changes in the functional state of the systems under study.The dependence of the detected changes on the time elapsed after radiation damage, the dose of γ-irradiation and the sex of the animals is clearly monitored.4. Females have been shown to be more radioresistant than males.

Postharvest application of thiol compounds affects surface browning and antioxidant activity of fresh-cut potatoes.

The aim of this study was to compare the effects of sodium metabisulphite and the thiol compounds, glutathione (GSH), L-cysteine (CYS), and N-acetylcysteine (NAC), on the enzymatic browning, antioxidant activities, total phenolic, and ascorbic acid content of potatoes after 1, 24, and 48hr. Three different concentrations (0.5%, 1.0%, and 2.0%) of each thiol compound were tested. While sulphite solution inhibited polyphenol oxidase as expected, NAC and CYS also decreased its activity. CYS-treated samples exhibited the highest residual thiol content, while the amount of residual thiol in GSH-treated samples was the lowest. The 2.0% NAC and 2.0% CYS solutions were the most effective at increasing antioxidant activity and ascorbic acid content; however, the results of total phenolic content assays were complicated. In summary, solutions containing 2.0% NAC, 1.0% CYS, and 2.0% CYS prevented enzymatic browning and increased the residual thiol content, ascorbic acid, and antioxidant activities of fresh-cut potatoes significantly, but GSH did not significantly inhibit browning. PRACTICAL APPLICATIONS: Fresh-cut potatoes are susceptible to enzymatic browning, which significantly reduces their commercial value. In literature, there have been several methods to protect the enzymatic browning of fruits and vegetables. Among these methods, thiols are good inhibitors of enzymatic browning. So, GSH, CYS, and NAC were used in this study. The outcomes of current work may help to inhibit polyphenol oxidase activity and increase the ascorbic acid content, residual thiol content, and antioxidant activity of fresh-cut potatoes. Both CYS and NAC may be useful alternatives to sulphite anti-browning agents, which may have adverse health effects.

Differential effects of Zn concentrations on Cr(VI) uptake by two Salvinia species: involvement of thiol compounds

Floating ferns of the genus Salvinia have great potential for phytoremediation of heavy metals. To date, the effect of essential metals on the accumulation and transport of toxic metals by aquatic ferns has not been suitably established. The aim of this study was to compare the ability of floating leaves of Salvinia minima and Salvinia rotundifolia species to accumulate Cr from Cr(VI solutions containing very low (0.02 mg L−1) and low (5 mg L−1) Zn concentrations. After 7-day metal-exposure period, results showed that Zn increased Cr accumulation in S. minima leaves whereas in S. rotundifolia decreased significantly. Contrarily Zn accumulation did not show great differences between species. This fact may indicate that Zn interfere Cr(VI) uptake by S. rotundifolia. Bioconcentration factor (BCF) and translocation factor (TF) were affected differently by Zn in both Salvinia species. Membrane stability index (MSI) of both Salvinia species was decreased significantly by 5 mg L−1 Zn concentration. Zn ions also increased hydrogen peroxide accumulation in fronds of Salvinia species. Total thiols (TT), non-protein thiols (NPT) and protein-bound thiols (PBT) were differentially affected by Cr(VI) and Zn ions. This study provides evidences on the involvement of different mechanisms against Cr(VI)/Zn toxicity in S. minima and S rotundifolia species.

Multiple enzymes can make hydrogen sulfide from cysteine in Treponema denticola

Treponema denticola is a spirochete that is involved in causing periodontal diseases. This bacterium can produce H2S from thiol compounds found in the gingival crevicular fluid. Determining how H2S is made by oral bacteria is important since this molecule is present at high levels in periodontally-diseased pockets and the biological effects of H2S can explain some of the pathologies seen in periodontitis. Thus, it is of interest to identify the enzyme, or enzymes, involved in the synthesis of H2S by T. denticola. We, and others, have previously identified and characterized a T. denticola cystalysin, called HlyA, which hydrolyzes cysteine into H2S (and pyruvate and ammonia). However, there have been no studies to show that HlyA is, or is not, the only pathway that T. denticola can use to make H2S. To address this question, allelic replacement mutagenesis was used to make a deletion mutant (ΔhlyA) in the gene encoding HlyA. The mutant produces the same amount of H2S from cysteine as do wild type spirochetes, indicating that T. denticola has at least one other enzyme that can generate H2S from cysteine. To identify candidates for this other enzyme, a BLASTp search of T. denticola strain 33520 was done. There was one gene that encoded an HlyA homolog so we named it HlyB. Recombinant His-tagged HlyB was expressed in E. coli and partially purified. This enzyme was able to make H2S from cysteine in vitro. To test the role of HlyB in vivo, an HlyB deletion mutant (ΔhlyB) was constructed in T. denticola. This mutant still made normal levels of H2S from cysteine, but a strain mutated in both hly genes (ΔhlyA ΔhlyB) synthesizes significantly less H2S from cysteine. We conclude that the HlyA and HlyB enzymes perform redundant functions in vivo and are the major contributors to H2S production in T. denticola. However, at least one other enzyme can still convert cysteine to H2S in the ΔhlyA ΔhlyB mutant. An in silico analysis that identifies candidate genes for this other enzyme is presented.

Isolation and analysis of a non-protein low molecular weight thiol-mercurial adduct from human prostate lymph node cells (LNCaP).

Thiol compounds present in human malignant prostate cells (LNCaP) were investigated after reaction with a mercurial blocking reagent. After extracting the cellular glutathione and some other low molecular weight (LMW) thiols using trichloroacetic acid the resulting the protein precipitate was extracted with buffered 8 M urea containing 2-chloromercuri-4-nitrophenol in an equimolar amount to that of the thiol present. After removing the insoluble chromatin fraction the urea soluble labeled adducts formed were chromatographed on G15 Sephadex. Three yellow coloured (A410 nm) fractions were obtained; first, the excluded protein fraction containing 16.0 ± 4.1% of the applied label followed by an intermediate fraction containing 5.9 ± 1.2%. Finally a LMW fraction emerged which contained 77.2 ± 3.7% of the total label applied and this was further analyzed by column chromatography, first on an anion exchange column and then on a PhenylSepharose 6 column to give what appeared to be a single component. LC–MS analysis of this component gave a pattern of mercuri-clusters, formed on MS ionization showing possible parent ions at 704 or 588 m/z, the former indicating that a thiol fragment of molecular weight approximately 467 could be present. No fragments with a single sulfur adduct (a 369 m/z fragment) were observed The adduct was analyzed for cysteine and other amino acids, nucleic acid bases, ribose and deoxyribose sugars, selenium and phosphorus; all were negative leading to the conclusion that a new class of unknown LMW thiol is present concealed in the protein matrices of these cells.

Inhibitory effect of alpha-lipoic acid on mitochondrial dysfunction and interleukin-8 expression in interleukin-1beta-stimulated ataxia teleangiectasia fibroblasts.

Ataxia telangiectasia (A-T) is an inherited neurodegenerative disease caused by mutation in the ataxia telangiectasia mutated (ATM) gene, leading to loss of function in the encoded protein ATM. Because ATM functions to reduce oxidative stress by up-regulating antioxidant enzymes, oxidative stress is a prevalent A-T phenotype and a mediator of the inflammation that drives A-T pathology. Reactive oxygen species (ROS) levels and the expression of pro-inflammatory cytokine interleukin-8 (IL-8) were higher in A-T cells than in normal cells. ROS are related to mitochondrial dysfunction and activation of nuclear factor kappa B (NF-κB) to induce IL-8 expression. Alpha-lipoic acid (α-LA), a naturally occurring thiol compound, shows an antioxidant effect in various cells. This study is aimed to determine if α-LA confers protection against NF-κB activation, IL-8 expression, and mitochondrial dysfunction in A-T cells which are exposed to the inflammatory cytokine IL-1β. A-T fibroblasts were treated with or without α-LA. The levels of intracellular and mitochondrial ROS, mRNA and protein levels of IL-8, mitochondrial membrane potential (MMP), ATP levels, and DNA binding activity of NF-κB were determined. As a result, IL-1β increased NF-κB activation, IL-8 expression, intracellular and mitochondrial ROS levels, but decreased MMP and ATP level in A-T cells. Pretreatment of A-T cells with α-LA inhibited IL-1β-induced activation of NF-κB, IL-8 expression, and mitochondrial dysfunction by reducing ROS levels. In conclusion, supplementation with α-LA may be beneficial for reducing the oxidative stress-induced mitochondrial dysfunction and IL-8 production associated with A-T.

Sequential desulfurization of thiol compounds containing liquid fuels: Adsorption over Ni-doped carbon beads followed by biodegradation using environmentally isolated Bacillus zhangzhouensis

Desulfurization of liquid fuels over a wide concentration range continues to be challenging. This study recommends a novel hybrid route to efficiently desulfurizing the thiols or organosulfur compounds containing liquid fuels. The tests performed on the dibenzothiophene (DBT) and thiophene (TH) containing n-octane over sulfur concentration range 300–1200 mg/L showed adsorptive desulfurization followed by the bacterial treatment to be efficient in decreasing the concentration level to 3–15 mg/L at 30 °C and 1 atm pressure. Adsorption performed using the Ni nanoparticles-dispersed porous carbon beads of ~ 0.8 mm size was effective at relatively higher concentrations. Upon nearly saturation in the adsorption step, further removal of the thiol compounds to low concentrations was possible by bacterial degradation using Bacillus zhangzhouensis isolated from the wastewater effluent of a petroleum industry. Fresh and spent adsorbents were characterized using various analytical techniques. Bacterial characterization involved the Christian gram staining and 16S rRNA sequencing. The data demonstrate for the first time ~ 99% removal of the thiol compounds, at rates faster than adsorption alone. The proposed sequential approach in this study can be effective in meeting the globally ever increasing stringent regulations for low sulfur content in fuel oils.

Synthesis of HA-SS-MP: A Prodrug With High Specificity for Cancer Cells

Thiolated hyaluronic acid was synthesized, and a quantification method was established to determine the content of the thiol group. Three thiol compounds, 2-nitro-5-mercapto-benzoic acid (TNB), 2- mercaptonicotinic acid (2-MNA), and mercaptopyridine (MPD), were tested for their efficiency in forming adducts with hyaluronic acid (HA) through disulfide bonds. Our results showed that MPD exhibited the highest disulfide exchange efficiency when the reaction was conducted at the optimal pH value. The synthesized hyaluronic acid-SS-mercaptopurine (HA-SS-MP) was characterized by 1H-nuclear magnetic resonance spectroscopy. The HA-SS-MP micelle showed a particle size of 264.4 nm in aqueous solution. An in vitro release experiment demonstrated that the releasing rate of 6-MP from HA-SS-MP in the release medium containing glutathione (GSH) was much higher than that in the release medium without GSH. Cell uptake experiments demonstrated the CD44 targeting of hyaluronic acid. Cytotoxicity tests in mouse melanoma cells (B16F10) showed that HA-SS-MP can kill melanoma cells effectively and with lower cytotoxicity, compared with the active ingredient, 6-MP.