Release Of Hydrogen Sulfide Research Articles

Controlled release of hydrogen sulfide significantly reduces ROS stress and increases dopamine levels in transgenic C. elegans.

Hydrogen sulfide, an endogenous signalling molecule, is central to several pathophysiological processes in mammalian systems. It scavenges reactive oxygen species and is known to ameliorate dopaminergic neuronal degeneration in neurotoxin-induced Parkinson's disease models. The rapid volatilization of H2S from spontaneously releasing sulfide salts being a challenge, we describe peptide conjugates which exhibit tris(2-carboxyethyl)phosphine mediated "slow and sustained" H2S release. These conjugates reduced hydrogen peroxide-induced oxidative stress and significantly increased dopamine levels in transgenic C. elegans.

Thiotaurine: From Chemical and Biological Properties to Role in H2S Signaling.

In the last decade thiotaurine, 2-aminoethane thiosulfonate, has been investigated as an inflammatory modulating agent as a result of its ability to release hydrogen sulfide (H2S) known to play regulatory roles in inflammation. Thiotaurine can be included in the "taurine family" due to structural similarity to taurine and hypotaurine, and is characterized by the presence of a sulfane sulfur moiety. Thiotaurine can be produced by different pathways, such as the spontaneous transsulfuration between thiocysteine- a persulfide analogue of cysteine- and hypotaurine as well as in vivo from cystine. Moreover, the enzymatic oxidation of cysteamine to hypotaurine and thiotaurine in the presence of inorganic sulfur can occur in animal tissues and last but not least thiotaurine can be generated by the transfer of sulfur from mercaptopyruvate to hypotaurine catalyzed by a sulfurtransferase. Thiotaurine is an effective antioxidant agent as demonstrated by its ability to counteract the damage caused by pro-oxidants in the rat. Recently, we observed the influence of thiotaurine on human neutrophils functional responses. In particular, thiotaurine has been found to prevent human neutrophil spontaneous apoptosis suggesting an alternative or additional role to its antioxidant activity. It is likely that the sulfane sulfur of thiotaurine may modulate neutrophil activation via persulfidation of target proteins. In conclusion, thiotaurine can represent a biologically relevant sulfur donor acting as a biological intermediate in the transport, storage and release of sulfide.

Improved growth of pea, lettuce, and radish plants using the slow release of hydrogen sulfide from GYY-4137.

Hydrogen sulfide (H2S) is a key gasotransmitter in agriculture and has been reported to increase the growth of plants in the first two weeks and to mitigate the effects of environmental stressors. GYY-4137 is widely used in these studies because it slowly releases H2S, but there is disagreement as to whether it requires enzymes to release H2S. In this article we describe the release of H2S in water without enzymes and that it releases H2S faster in organic solvents than in water or when mixed in topsoil. Furthermore, we describe the long-term effect of dosing pea, radish, and lettuce plants with GYY-4137 for up to six weeks. The effect of GYY-4137 on plant growth for six weeks was either positive or negative depending on the loading of GYY-4137 and how it was applied to plants. The addition of GYY-4137 to lettuce plants via potting mix resulted in reduced growth and death of the plants. In contrast, application of GYY-4137 to the leaves of lettuce plants increased the harvest weight of the leaves by up to 86%. Our results demonstrate that GYY-4137 can have a positive, important effect on the growth of plants but that this effect is dependent on several factors.

Efficacy of isothiocyanate-based compounds on different forms of persistent pain.

PurposeCurrent pharmacotherapy for persistent pain related to neuropathy or articular diseases is unsatisfactory, due to the large number of unresponsive patients and side effects. Isothiocyanates (ITCs) are a class of natural or synthetic compounds characterized by the general formula R–NCS. ITCs show antihyperalgesic effects in models of central and peripheral nervous tissue injury and anti-inflammatory properties. The pharmacodynamics are strictly related to the release of the gasotransmitter hydrogen sulfide (H2S) from their moiety. In particular, phenyl ITC (PITC) and 3-carboxyphenyl ITC (3C-PITC) exhibit interesting slow H2S-release properties suitable for treating painful pathology. The aim of the present work was to evaluate the efficacy of PITC and 3C-PITC against mechanical hyperalgesia and spontaneous pain induced by nerve injury and osteoarthritis.MethodsNerve injury and osteoarthritis were induced in rats by ligation of the sciatic nerve (chronic constriction injury) and intra-articular injection of monoiodoacetate, respectively. Behavioral tests were performed 14 days after damage induction.ResultsSingle subcutaneous administrations of PITC, 3C-PITC (4.43 and 13.31 µmol kg−1, respectively) were able to completely reverse hypersensitivity to noxious stimuli in both models of neuropathic and osteoarticular pain. The effect of ITCs was compared with that of NaHS, the prototypical H2S donor, showing similar efficacy and higher potency. ITCs and NaHS also reduced spontaneous pain.ConclusionITCs offer a promising novel approach to counteract persistent, drug-resistant painful pathology.

243 - Modulation of NLRP3 inflammasome activation in human macrophages by slow release hydrogen sulfide compounds

The NLRP3 inflammasome complex undergoes priming and activation leading to pro-inflammatory IL-1β and IL-18 synthesis. This study investigated the potential role of mitochondrial redox modulation in activation of the NLRP3 inflammasome in human cells. THP-1 cells were differentiated to macrophages with PMA for 24 hours and the NLRP3 inflammasome primed with LPS (0.1µg/ml) followed by activation with bzATP. NLRP3 and pro-IL1β were detected by Western blotting and ASC speck formation by immunofluorescence as markers of NLRP3 inflammasome priming. IL-1β and IL-18 in cell media were quantified by ELISA as markers of inflammasome activation. Under the conditions employed, intracellular oxidant generation (mitoparaquat and paraquat; Pq) assessed by mitoSOX fluorescence, was not sufficient to prime macrophages and did not affect priming mediated by LPS. At a relatively high extracellular concentration (5 µM) mitoPq, but not Pq, was able to increase IL-1β production in LPS-primed macrophages, suggesting promotion of inflammatory responses; IL-18 production was not affected. In LPS-primed and bzATP activated cells, the non-targeted slow release H2S compound, GYY4137, slightly reduced IL-1β production but was able to reduce IL-18 synthesis by approximately 50%. Although the mitochondria-targeted, slow release H2S compound AP39 did not affect inflammasome priming, at 300 nM (final media concentration) it reduced IL-1β and IL-18 synthesis in primed and activated cells. These data support a role for redox active oxygen and sulfur species, particularly when targeted to mitochondria, in modulating inflammatory cytokine synthesis in human macrophages with pro- and anti-inflammatory activities respectively.

Reviewing microbial electrical systems and bacteriophage biocontrol as targeted novel treatments for reducing hydrogen sulfide emissions in urban sewer systems

Microbially induced concrete corrosion (MICC) is a costly, and ongoing problem affecting the infrastructure of water utilities worldwide. Traditionally MICC has been treated with chemicals and physical techniques that inhibit the release of hydrogen sulfide (H2S), preventing sulfuric acid formation and the consequent corrosion. However, these methods require continual dosing and monitoring to ensure process efficiency and prevent undue costs. This review focuses on recent research into two potential novel treatments for MICC: re-engineering the sewer sulfur cycle by removing sulfide using electrodes in microbial electrical systems as an alternative electron acceptor and; altering the microbial community using targeted bacteriophage biocontrol to reduce specific sulfide-producing bacteria. These novel treatments hold the potential to reduce water utilities reliance on continual chemical dosing providing a long-lasting treatment I believe necessitates further laboratory and field-trial investigation.

Clopidogrel as a donor probe and thioenol derivatives as flexible promoieties for enabling H2S biomedicine

Hydrogen sulfide has emerged as a critical endogenous signaling transmitter and a potentially versatile therapeutic agent. The key challenges in this field include the lack of approved hydrogen sulfide-releasing probes for in human exploration and the lack of controllable hydrogen sulfide promoieties that can be flexibly installed for therapeutics development. Here we report the identification of the widely used antithrombotic drug clopidogrel as a clinical hydrogen sulfide donor. Clopidogrel is metabolized in patients to form a circulating metabolite that contains a thioenol substructure, which is found to undergo spontaneous degradation to release hydrogen sulfide. Model studies demonstrate that thioenol derivatives are a class of controllable promoieties that can be conveniently installed on a minimal structure of ketone with an α-hydrogen. These results can provide chemical tools for advancing hydrogen sulfide biomedical research as well as developing hydrogen sulfide-releasing drugs.

Comparative Effects of Hydrogen Sulfide-Releasing Compounds on [3H]D-Aspartate Release from Bovine Isolated Retinae.

We investigated the pharmacological actions of a slow-releasing H2S donor, GYY 4137; a substrate for the biosynthesis of H2S, L-cysteine and its precursor, N-acetylcysteine on potassium (K+; 50mM)-evoked [3H]D-aspartate release from bovine isolated retinae using the Superfusion Method. GYY 4137 (10nM-10µM), L-cysteine (100nM-10µM) and N-acetylcysteine (10µM-1mM) elicited a concentration-dependent decrease in K+-evoked [3H]D-aspartate release from isolated bovine retinae without affecting basal tritium efflux. At equimolar concentration of 10µM, the rank order of activity was as follows: L-cysteine > GYY 4137 > N-acetylcysteine. A dual inhibitor of the biosynthetic enzymes for H2S, cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), amino-oxyacetic acid (AOA; 3mM) reversed the inhibitory responses caused by GYY 4137, L-cysteine and N-acetylcysteine on K+-evoked [3H]D-aspartate release. Glibenclamide (300µM), an inhibitor of KATP channels blocked the inhibitory action of GYY 4137 and L-cysteine but not that elicited by N-acetylcysteine on K+-induced [3H]D-aspartate release. The inhibitory effect of GYY 4137 and L-cysteine onK+-evoked [3H]D-aspartate release was reversed by the non-specific inhibitor of nitric oxide synthase (NOS), L-NAME (300µM). Furthermore, a specific inhibitor of inducible NOS(iNOS), aminoguanidine (10µM) blocked the inhibitory action of L-cysteine on K+-evoked [3H]D-aspartate release. We conclude that both donors and substrates for H2S production can inhibit amino acid neurotransmission in bovine isolated retinae, an effect that is dependent, at least in part, upon the intramural biosynthesis of this gas, and on the activity of KATP channels and NO synthase.

Multiple role of 3-mercaptopyruvate sulfurtransferase: antioxidative function, H2 S and polysulfide production and possible SOx production.

Rat 3-mercaptopyruvate sulfurtransferase (MPST) is a 32 808Da simple protein. Cys247 is a catalytic site, and Cys154 and Cys263 are on the enzyme surface. MPST is found in all tissues, particularly in the kidneys, although the localization of its activity differs in each tissue. In this review, four functions of MPST are reviewed: (i) antioxidative function: Cys247 is redox-sensitive and serves as a redox-sensing switch. It is oxidized to cysteine sulfenate, which has a low redox potential, upon which the enzyme is inactivated. Then, reduced thioredoxin (Trx) with a reducing system (Trx reductase and NADPH) reduces the sulfenate to restore activity; meanwhile, Cys154 and Cys263 form an intermolecular disulfide bond, which serves as another redox-sensing switch. Consequently, Trx specifically cleaves the intermolecular disulfide bond by converting it from the inactive form (dimer) to the active form (monomer). (ii) Hydrogen sulfide and polysulfide production: hydrogen sulfide is produced via reduction of the persulfurated sulfur-acceptor substrate by reduced Trx or Trx with a reducing system; as an alternative process, stable polysulfurated or persulfurated Cys247 as a reaction intermediate is reduced by Trx with a reducing system to release hydrogen sulfide and polysulfides. (iii) Possible sulfur oxide production: sulfur oxides (SO, SO2 and SO3 ) can be produced in the redox cycle of sulfane sulfur formed at the catalytic site Cys247 (Cys-SO- , Cys-SO2- and Cys-SO3- ) as reaction intermediates and released by reduced Trx or Trx with a reducing system. (iv) Possible anxiolytic-like effects: MPST-knockout mice exhibited anxiolytic-like effects.

Determination of decomposition-related volatile organic compounds from different pig tissues for environmental and forensic applications

Event Abstract Back to Event Determination of decomposition-related volatile organic compounds from different pig tissues for environmental and forensic applications Dibyendu Dutta1, 2, Samantha T. Keene1 and Ngee S. Chong1* 1 Middle Tennessee State University, Department of Chemistry, United States 2 New York Medical College, Department of Medicine, United States Research on the decomposition chemistry of porcine tissues is beneficial in environmental and forensic fields. The environmental management issues regarding the disposal of animal carcasses in catastrophic events with large human and livestock casualty require a detailed understanding of degradation by-products that could be released into the environmental media of soil, water, and air. Furthermore, the insights gained from research on decomposition of porcine tissues can be conducive toward the training of cadaver dogs for crime scene investigation, determining the presence of trace chemical evidence of decomposed tissues, and the estimation of postmortem interval (PMI) in homicide investigation. In this project, gas chromatography coupled with mass spectrometry (GC-MS) was used to identify and quantify postmortem volatile organic compounds (VOCs). Different types of pig tissues including skins, bones, muscle, and blood were used to investigate decomposition-related VOCs over a series of time-intervals over a period of 72 days. In blood, ethylbenzene appeared in the initial decomposition stages, and styrene and benzaldehyde peaked till late stages of decomposing. While phenylalanine may be the common source of origin of these compounds in blood, ethylbenzene can undergo dehydrogenation to form styrene, which can later produce benzaldehyde through oxidation. In bones, methanethiol and dimethyl sulfide appear during early decomposing stages, and become undetectable after day 23 due to their subsequent conversion to dimethyl disulfide. Besides being the by-products of bacterial metabolism, these sulfur compounds may also come from chemical degradation of methionine. While dimethyl sulfide and methanethiol can be the direct by-products of methionine degradation, dimethyl sulfide can also be formed by the release of hydrogen sulfide via intermolecular reaction of two methanethiol molecules. The subsequent formation dimethyl disulfide and dimethyl trisulfide was also observed. Thus, ethylbenzene, benzaldehyde, dimethyl sulfide, dimethyl disulfide and dimethyl trisulfide may be used as potential markers for PMI estimation. Keywords: Decomposition chemistry, Postmortem interval (PMI), Volatile organic compounds (V.O.C.), GC-MS (gas chromatography-mass spectrometry), forensic chemistry Conference: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference , Orlando, Florida, United States, 17 Sep - 20 Sep, 2018. Presentation Type: Oral Presentation Topic: Enviornmental and Green Chemistry Citation: Dutta D, Keene ST and Chong NS (2019). Determination of decomposition-related volatile organic compounds from different pig tissues for environmental and forensic applications. Front. Chem. Conference Abstract: National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE) 45th Annual Conference . doi: 10.3389/conf.fchem.2018.01.00008 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 25 Sep 2018; Published Online: 17 Jan 2019. * Correspondence: Dr. Ngee S Chong, Middle Tennessee State University, Department of Chemistry, Murfreesboro, United States, Ngee.Chong@mtsu.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Dibyendu Dutta Samantha T Keene Ngee S Chong Google Dibyendu Dutta Samantha T Keene Ngee S Chong Google Scholar Dibyendu Dutta Samantha T Keene Ngee S Chong PubMed Dibyendu Dutta Samantha T Keene Ngee S Chong Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Gypsum Bedding Impact on Hydrogen Sulfide Release from Dairy Manure Storages

Abstract. Elevated hydrogen sulfide (H2S) levels have been observed from open-air dairy manure storages that contain gypsum bedding. Gypsum (calcium sulfate), recycled from construction waste and manufacturing defects, provides a cost-effective bedding alternative for dairy cows. Gypsum bedding is reported to control moisture and bacteria in the stalls and can improve soil structure when land-applied. However, gypsum increases H2S production in the anaerobic environment of deep manure storages, which is released in dangerous concentrations when the manure is agitated. This study was undertaken to quantify and compare the H2S concentrations during agitation of manure storages for three dairy stall management categories: farms that use (1) traditional organic bedding, (2) gypsum bedding, and (3) gypsum bedding followed by a treatment added to the manure storage thought to reduce H2S emissions. Three farms used Vital Breakdown (manufactured by Homestead Nutrition, New Holland, Pa.), and one farm used OK-1000 (Pro Ag Solutions, Hawkins, Tex.). Nineteen agitation events at ten farms were monitored during spring and fall hauling seasons. Portable monitoring instruments recorded H2S concentrations around the perimeter of the manure storages prior to and during agitation. Results show that manure storage agitation at farms that use gypsum bedding produced H2S concentrations that were considered immediately dangerous to life and health (above 100 ppm). Increasing gypsum bedding use significantly increased cumulative H2S concentrations (p < 0.0001). Farms that used Vital Breakdown as an amendment significantly reduced cumulative H2S concentrations when compared to farms not using a manure treatment (p < 0.0001). Lower cumulative H2S concentrations at one farm were attributed to the OK-1000 manure treatment. Keywords: Cow, Dairy, Gas, Gypsum, Hydrogen sulfide, Manure, Safety.

Quantification of Hydrogen Sulfide and Cysteine Excreted by Bacterial Cells.

Bacteria release cysteine to moderate the size of their intracellular pools. They can also evolve hydrogen sulfide, either through dissimilatory reduction of oxidized forms of sulfur or through the deliberate or inadvertent degradation of intracellular cysteine. These processes can have important consequences upon microbial communities, because excreted cysteine autoxidizes to generate hydrogen peroxide, and hydrogen sulfide is a potentially toxic species that can block aerobic respiration by inhibiting cytochrome oxidases. Lead acetate strips can be used to obtain semiquantitative data of sulfide evolution (Oguri et al., 2012). Here we describe methods that allow more-quantitative and discriminatory measures of cysteine and hydrogen sulfide release from bacterial cells. An illustrative example is provided in which Escherichia coli rapidly evolves both cysteine and sulfide upon exposure to exogenous cystine (Chonoles Imlay et al., 2015; Korshunov et al., 2016).

Tetraphenylethylene conjugated p-hydroxyphenacyl: fluorescent organic nanoparticles for the release of hydrogen sulfide under visible light with real-time cellular imaging.

Hydrogen sulfide (H2S) behaves like a two-edged sword, at low concentrations it has beneficial and cytoprotective effects, while at higher concentrations it exhibits toxicity. Hence there is a keen interest in developing light responsive H2S donors with a spatio-temporal controlled release. Herein, we report visible light activatable tetraphenylethylene conjugated p-hydroxyphenacyl (TPE-pHP-H2S) nanoparticles for the release of hydrogen sulfide (H2S) with a real time monitoring ability. Our newly designed photoresponsive single component organic nanoparticle based H2S donor is built by integrating the tetraphenylethylene (TPE) moiety and p-hydroxyphenacyl (pHP) group so that it can display both aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT) properties. Aggregation-induced emission enhancement was exhibited by our TPE-pHP-H2S NP donor, which was then explored for the cellular imaging application. The ESIPT by the pHP moiety provided unique advantages to our TPE-pHP-H2S NP donor which include (i) the excitation wavelength extended to >410 nm (ii) a large Stokes shift (iii) a low inner filter effect and (iv) real-time monitoring of H2S release by a simple fluorescent colour change. In vitro studies showed that the TPE-pHP-H2S NP donor presents excellent properties like real-time monitoring, photoregulated H2S release and biocompatibility.

Environmental Depredation and Aesthetic Reflection in Wilhelm Raabe’s Late Fiction

In the winter of 1890 to 1891 the city of Braunschweig experienced a precipitous decline in the quality of its drinking water. The cause: beet sugar factories in the surrounding duchy were releasing hydrogen sulfide—the major byproduct of beet sugar production—into the Oker River watershed in quantities that exceeded the capacity of local water purification facilities. Wilhelm Raabe described the town’s situation in a letter to his daughter on January 17, 1891: “Be glad that you are not in Braunschweig. An absolute pigsty! We no longer bathe, we no longer brush our teeth, even in our cooked food you can taste the water from the Oker, spoiled by twelve sugar factories: Pfister′s Mill in its most terrible completion!” (Stadtarchiv Braunschweig, H III 10 : 2).1 The letter describes the intrusion of a byproduct of modern industry into a city that Raabe had once praised for the “ancient magnificence and beauty of lower Saxon bourgeois splendor.”2 In the letter Raabe understands environmental crisis as an aesthetic crisis, one that then precipitates a civilizational crisis: quotidian habits of hygiene and consumption are suddenly disrupted as the ugly signs of modern industry move from the duchy’s peripheral industrial settlements into the beautiful, pre-industrial urban core. Pfister’s Mill (Pfisters Mühle) is Raabe’s 1884 novel about water pollution from a beet sugar factory driving a mill out of business. If Pfister’s Mill reaches its “most terrible completion” in the calamity of 1891, then it is because what appeared in the novel as an individual tragedy has grown into a disaster for an entire city.

Release of hydrogen sulfide under intermittent flow conditions - the potential of simulation models.

For engineering purposes it is especially useful to be able to predict and control sewer corrosion rates and odor impacts as well as to design effective measures aiming to reduce effects related to hydrogen sulfide formation and release. Doing so, it is important to use modeling tools that are capable of assessing variations of dissolved oxygen, dissolved sulfide and hydrogen sulfide gas concentrations for a wide range of environmental scenarios. Two such models were assessed: AEROSEPT, an empirical formulation, and WATS, a conceptual and more complex approach. The models were applied to evaluate the effects of transitions between pressure mains and gravity sewers in the air-liquid mass transfer of hydrogen sulfide at the Ericeira sewer system in Portugal. This network is known to have odor and corrosion problems, especially during summer. Despite the unavoidable uncertainties due to the unsteady flow rate and the quantification of air velocity and turbulence, the simulation results obtained with both models have been shown to adequately predict the overall behavior of the system.

Metabolic, Cardiac, and Renal Effects of the Slow Hydrogen Sulfide-Releasing Molecule GYY4137 During Resuscitated Septic Shock in Swine with Pre-Existing Coronary Artery Disease.

Decreased levels of endogenous hydrogen sulfide (H2S) contribute to atherosclerosis, whereas equivocal data are available on H2S effects during sepsis. Moreover, H2S improved glucose utilization in anaesthetized, ventilated, hypothermic mice, but normothermia and/or sepsis blunted this effect. The metabolic effects of H2S in large animals are controversial. Therefore, we investigated the effects of the H2S donor GYY4137 during resuscitated, fecal peritonitis-induced septic shock in swine with genetically and diet-induced coronary artery disease (CAD). Twelve and 18 h after peritonitis induction, pigs received either GYY4137 (10 mg kg, n = 9) or vehicle (n = 8). Before, at 12 and 24 h of sepsis, we assessed left ventricular (pressure-conductance catheters) and renal (creatinine clearance, blood NGAL levels) function. Endogenous glucose production and glucose oxidation were derived from the plasma glucose isotope and the expiratory CO2/CO2 enrichment during continuous i.v. 1,2,3,4,5,6-C6-glucose infusion. GYY4137 significantly increased aerobic glucose oxidation, which coincided with higher requirements of exogenous glucose to maintain normoglycemia, as well as significantly lower arterial pH and decreased base excess. Apart from significantly lower cardiac eNOS expression and higher troponin levels, GYY4137 did not significantly influence cardiac and kidney function or the systemic inflammatory response. During resuscitated septic shock in swine with CAD, GYY4137 shifted metabolism to preferential carbohydrate utilization. Increased troponin levels are possibly due to reduced local NO availability. Cautious dosing, the timing of GYY4137 administration, and interspecies differences most likely account for the absence of any previously described anti-inflammatory or organ-protective effects of GYY4137 in this model.

Triggered and Tunable Hydrogen Sulfide Release from Photogenerated Thiobenzaldehydes.

Hydrogen sulfide (H2 S) has been identified as an important cell-signaling mediator and has a number of biological functions, such as vascular smooth muscle relaxation, neurotransmission, and regulation of inflammation. A facile and versatile approach for H2 S production initiated by light irradiation and controlled by reaction with an amine or an amino acid was developed. The donor was synthesized in a one-pot reaction, and simple crystallization led to a yield of approximately 90 %. The synthetic strategy is scalable and versatile, and the H2 S donors can be expressed ina number of different molecular and macromolecular forms, including crystalline small-molecule compounds, water-soluble polymers, polystyrene films, and hydrogels. The H2 S donors based on polystyrene film and hydrogel were used as cell-culture scaffolds. The H2 S donor based on water-soluble polymer was applied in photocontrolled inhibition of P-selectin expression on human platelets and subsequent regulation of platelet aggregation. This study provides the simplest controllable H2 S source to study its biological functions. The developed materials are also new therapeutic platforms to deliver H2 S, as there is no accumulation of toxic byproducts, and the donor materials from polystyrene films and hydrogels can be readily removed after releasing H2 S.

H2S Donors in creation of innovative drugs

Fundamental studies have identified a new group of gaseous signaling molecules – the so-called gasotransmitters – NO, CO, and H2S, which are involved in the regulation of a large number of metabolic processes. The results of these studies allowed determining a new direction in medicinal/pharmaceutical chemistry – creation of hydrogen sulfide donor compounds as potential drugs. The article presents the main achievements in the search for new H2S donors: the main stages of H2S metabolism and its biological effects; the classes of compounds that can release hydrogen sulfide based on the nature of sulfur-containing functional groups as well as the mechanism of H2S releasing. Additionally, the characteristic of the most successful direction – creation of the so-called hybrid molecules is given. The latter are compounds bearing fragments of the well known drugs covalently bounded with groups being capable to release H2S.

H2S-Releasing Polymer Micelles for Studying Selective Cell Toxicity.

We report the preparation of S-aroylthiooxime (SATO) functionalized amphiphilic block copolymer micelles that release hydrogen sulfide (H2S), a gaseous signaling molecule of relevance to various physiological and pathological conditions. The micelles release H2S in response to cysteine with a half-life of 3.3 h, which is substantially slower than a related small molecule SATO. Exogenous administration of H2S impacts growth and proliferation of cancer cells; however, the limited control over H2S generation from inorganic sulfide sources results in conflicting reports. Therefore, we compare the cellular cytotoxicity of SATO-functionalized micelles, which release H2S in a sustained manner, to Na2S, which releases H2S in a single dose. Our results show that H2S-releasing micelles significantly reduce the survival of HCT116 colon cancer cells relative to Na2S, GYY4137, and a small molecule SATO, indicating that release kinetics may play an important role in determining toxicity of H2S toward cancer cells. Furthermore, H2S-releasing micelles are well tolerated by immortalized fibroblasts (NIH/3T3 cells), suggesting a selective toxicity of H2S toward cancer cells.

Erratum: Water Science and Technology 75 (10), 2257-2267: Liquid-gas mass transfer at drop structures, Natércia Matias, Asbjørn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira and José Saldanha Matos, doi: 10.2166/wst.2017.103.

Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.