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Cyclization of hydroxy-substituted gem-chloronitroso compounds under the action of bases affords cyclic nitronates, namely, isoxazoline N-oxides and 5,6-dihydro-4H-1,2-oxazine N-oxides. The process is reversible, viz., the chloronitroso compounds are regenerated upon the action of hydrogen chloride on the cyclization products. A method for the synthesis of cyclic nitronates from aldols using the title reaction was developed. The cyclization mechanism was studied and the kinetic parameters of the process were determined using UV—Vis and IR monitoring and the results of quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Water is not a good solvent for most organic compounds, yet water can offer many benefits to some organic reactions, hence enriching organic chemistry. Herein, the unique divergent reactivity of 2‐substituted indoles with ⋅NO sources is presented. The amount of water solvent was harnessed for a scalable, benign, and expedient synthesis of indolenine oximes, albeit with water's inability to dissolve the reactants. 2‐Methoxyethyl nitrite, which has been tailored for reactions in water, empowered this protocol by enhancing the product selectivity. We further report on chemoselective transformations of the products that rely on their structural features. Our findings are expected to offer access to an underexplored chemical space. The platform is also applicable to oximinomalonate synthesis. Mechanistic studies revealed the important role of water in the reversal of stability between oxime and nitroso compounds, promoting the proton transfer. [ABSTRACT FROM AUTHOR]

This article discusses recent developments in the photocatalytic reduction of nitro compounds to valuable intermediates, such as amines and azo compounds. Nitro compounds are widely used in various industries but pose environmental and health hazards due to their toxicity and nondegradability. Traditional reduction methods often use harsh conditions and toxic chemicals, making the utilization of photocatalytic organic transformations an attractive option for sustainable and green chemical processes. The article provides an overview of different photocatalytic systems, including metal-organic frameworks, semiconductors, and nanocomposites, and explores their synthesis, performance, stability, recyclability, and selectivity. The use of hole scavengers and sacrificial reagents to enhance the reduction process is also mentioned. The studies demonstrate the potential of these photocatalytic systems for efficient and environmentally friendly nitro compound reduction. [Extracted from the article]

Metabolism of nitric oxide (NO) donors: dinitrosyl iron complexes (DNIC), nitrosothiols (RSNO), and nitroprusside was studied on a chick embryo model. The obtained results give reason to assume that DNIC constituting the main pool of nitroso compounds in the vast majority of tissues are NO donors immediately interacting with the physiological target of NO, and other NO donors can perform this function after their transformation into DNIC. NO is released from DNIC not spontaneously, but under a joint influence of a factor destroying the complex and a target having chemical affinity for NO. A similar mechanism is apparently implicated in NO passage through the cell membrane. [ABSTRACT FROM AUTHOR]

The azoxy functional group is an important structural motif and represents the formally oxidized counterpart of the azo group. Azoxy compounds find numerous applications ranging from pharmaceuticals to functional materials, yet their synthesis remains underdeveloped with a main focus on the formation symmetric azoxy compounds. To overcome challenges in the synthesis of such unsymmetric azoxy compounds, we designed a process employing readily accessible nitroso compounds and iminoiodinanes. This method builds on the use of visible light irradiation to generate a triplet nitrene from iminoiodinanes, which is trapped by nitroso arenes to give access to sulfonyl‐protected azoxy compounds with a good substrate scope and functional group tolerance. We further describe two applications of these sulfonyl‐protected azoxy compounds as radical precursors in synthesis, where the whole azoxy group can be transferred and employed in C(sp3)−H functionalization of ethers or 1,2‐difunctionalization of vinyl ethers. All of the reactions occurred at room temperature under visible light irradiation without the addition of any photoredox catalysts and additives. Control experiments, mechanism investigations, and DFT studies well explained the observed reactivity. [ABSTRACT FROM AUTHOR]

The azoxy functional group is an important structural motif and represents the formally oxidized counterpart of the azo group. Azoxy compounds find numerous applications ranging from pharmaceuticals to functional materials, yet their synthesis remains underdeveloped with a main focus on the formation symmetric azoxy compounds. To overcome challenges in the synthesis of such unsymmetric azoxy compounds, we designed a process employing readily accessible nitroso compounds and iminoiodinanes. This method builds on the use of visible light irradiation to generate a triplet nitrene from iminoiodinanes, which is trapped by nitroso arenes to give access to sulfonyl‐protected azoxy compounds with a good substrate scope and functional group tolerance. We further describe two applications of these sulfonyl‐protected azoxy compounds as radical precursors in synthesis, where the whole azoxy group can be transferred and employed in C(sp3)−H functionalization of ethers or 1,2‐difunctionalization of vinyl ethers. All of the reactions occurred at room temperature under visible light irradiation without the addition of any photoredox catalysts and additives. Control experiments, mechanism investigations, and DFT studies well explained the observed reactivity. [ABSTRACT FROM AUTHOR]

The aim of this work is to highlight the influence of UV light on the hydrolysis reaction of nifedipine (NIF) in the presence of alkaline solutions. In this context, the photodegradation of NIF in the absence of alkaline solutions caused (a) a change in the ratio between the absorbances of three bands in the UV-VIS spectra localized at 224–240 nm, 272–276 nm and 310–340 nm, assigned to the electronic transitions of -COOCH3 groups, -NO2 groups and a heterocycle with six atoms; (b) a red-shift of the photoluminescence (PL) band from 458 nm to 477 nm, simultaneous with an increase in its intensity; (c) a decrease in the ratio of the Raman line intensities, which peaked at 1224 cm−1 and 1649 cm−1, associated with the vibrational modes of -C-C-O in the ester group and C=C stretching; and (d) a decrease in the ratio between the absorbances of the IR bands, which peaked at 1493 cm−1 and 1223 cm−1, associated with the vibrational modes of the -NO2 group and C-N stretching. These changes were explained considering the NIF photodegradation reaction, which leads to the generation of the compound 4-(2-nitrosophenyl)-2.6-dimethyl-3.5-dimethoxy carbonyl pyridine. The interaction of NIF with NaOH in the absence of UV light was demonstrated to induce changes in the vibrational mode of the -C-C-O bond in the ester group. The photodegradation of NIF after its reaction with NaOH induces significant changes highlighted in its (a) UV-VIS spectra, by the shift of the absorption band at 238 nm; (b) PL spectra, by the supraunitary value of the ratio between the emission band intensities at 394–396 nm and 450 nm; (c) Raman spectra, by the change in the ratio between the intensities of the lines that peaked at 1224 cm−1 and 1649 cm−1 from 0.61 to 0.49; and (d) FTIR spectra, by the lowered absorbance of the IR band at 1493 cm−1 assigned to the vibrational mode of the -NO2 group as a result of the generation of the nitroso compound. These changes were explained considering the hydrolysis reaction products of NIF, as the nitroso compound is converted to a lactam-type compound. The photodegradation reaction rate constants of NIF and NIF after interaction with NaOH were also reported. The decrease in thermal stability of NIF samples after interaction with NaOH, as well as of NIF after exposure to UV light compared to NIF prior to exposure to UV light, was demonstrated by thermogravimetry, and the key fragments were confirmed by mass spectrometry. [ABSTRACT FROM AUTHOR]

Our main goal in this work is to synthesize valuable sulfonamide compounds according to the principles of green chemistry and also to present a unique convergent paired mechanism for their synthesis. In this study, we introduced a new type of convergent paired electro-organic synthesis of sulfonamide derivatives via a catalyst, oxidant, halogen and amine-free method. In this research, instead of using toxic amine compounds, an innovative mechanism based on the reduction of nitro compounds and in-situ production of amine compounds was used. The mechanism of electrophile generation is the cathodic reduction of the nitro compound to the hydroxylamine compound and then the anodic oxidation of the hydroxylamine to the nitroso compound. On the other hand, the nucleophile generation mechanism involves the two-electron oxidation of sulfonyl hydrazide to related sulfinic acid at the anode surface. The reaction leading to the synthesis of sulfonamides involves a one-pot reaction of the generated nitroso compound with the produced sulfinic compound. [ABSTRACT FROM AUTHOR]

Background and Aim: The risk factors for cholangiocarcinoma (CCA) are opisthorchiasis and the intake of a combination of nitroso compounds through the consumption of traditionally fermented fish, which is very popular in areas where liver flukes are endemic. The incidence of CCA remains high because this cultural habit of rural people has been altered. Therefore, decreasing nitrate and nitrite concentrations in fermented fish are an alternative approach to reducing the risk of CCA. Thus, this study aimed to reduce nitrate and nitrite concentrations in fermented foods by heating and investigated its effect on CCA development in a hamster model. Materials and Methods: We used Association of Official Analytical Chemists method 973.31 to measure the nitrate and nitrite concentrations in both fermented fish (pla-ra [PR]) and pickled fish (pla-som [PS]) before and after boiling for 5 and 30 min, respectively. The same samples were fed to Opisthorchis viverrini (OV)-infected or -uninfected hamsters for 3 months. Thereafter, the hamsters’ liver and blood were collected for analysis. Results: The levels of nitrates and nitrites in PS and PR significantly decreased following boiling for 5 and 30 min. The OV-PR and OV-PS groups showed dramatically increased numbers of inflammatory cells, fibrosis surrounding the bile duct, and focal fibrotic areas. However, after boiling the fermented dishes for 5 and 30 min, the extent of inflammatory cell infiltration and intensity of fibrosis in these groups were decreased. Conclusion: Our findings suggest that boiling reduces nitrate and nitrite toxicity in fermented dishes, as evidenced by reduced hepatic inflammation. However, regardless of heating, kidney tissues are adversely affected when fermented meals are consumed daily. [ABSTRACT FROM AUTHOR]

The direct N‐alkylation reactions of ambident 3,5‐substituted 4‐nitroso‐1H‐pyrazoles are described for the first time. An efficient method of the 4‐nitroso‐1H‐pyrazoles and their sodium alkyl‐, allyl‐ salts regioselective N‐alkylation by benzyl halides, halocarboxylic acids esters, and related bifunctional alkylating agents is established with the use of superbasic conditions or reflux in acetone. A series of new N‐functionalized nitrosopyrazoles and bis(4‐nitrosopyrazole) compounds is successfully obtained with a yield of up to 85 %. Using quantum‐chemical calculations, it is shown that in terms of kinetics and thermodynamics, the N‐alkylation of the considered pyrazoles is a more advantageous process than O‐alkylation. [ABSTRACT FROM AUTHOR]

A wide variety of synthetic methods have been developed for the synthesis of functionalized aliphatic amines because of their broad utility in both synthetic and medicinal chemistry. The synthesis of functionalized aliphatic amines via direct C–H functionalization of readily available aliphatic amines, the majority of which rely on the use of metallic reagents/catalysts and hazardous oxidants, is advantageous in comparison to the classical multistep approaches. However, the scope to carry out such direct C–H functionalization of aliphatic amines under metal and oxidant-free conditions is being continuously explored. As a result, the examples of C–H functionalization of aliphatic amines employing iminium/azonium ions, which are formed via classical condensation of amines and carbonyl/nitroso compounds, are on the rise. This article summarizes the recent developments in the iminium and azonium-activated metal and oxidant-free C–H functionalization of aliphatic amines with the main focus on the intermolecular reactions of iminium/azonium ions, enamines, and zwitterions with suitable nucleophiles, electrophiles and dipolarophiles. [ABSTRACT FROM AUTHOR]

The presence of hydrogen peroxide along with ferrous iron produces hydroxyl radicals that preferably oxidize polyunsaturated fatty acids (PUFA) to alkyl radicals (L•). The reaction of L• with an oxygen molecule produces lipid peroxyl radical (LOO•) that collectively trigger chain reactions, which results in the accumulation of lipid peroxidation products (LOOH). Oxygenase enzymes, such as lipoxygenase, also stimulate the peroxidation of PUFA. The production of phospholipid hydroperoxides (P-LOOH) can result in the destruction of the architecture of cell membranes and ultimate cell death. This iron-dependent regulated cell death is generally referred to as ferroptosis. Radical scavengers, which include tocopherol and nitric oxide (•NO), react with lipid radicals and terminate the chain reaction. When tocopherol reductively detoxifies lipid radicals, the resultant tocopherol radicals are recycled via reduction by coenzyme Q or ascorbate. CoQ radicals are reduced back by the anti-ferroptotic enzyme FSP1. •NO reacts with lipid radicals and produces less reactive nitroso compounds. The resulting P-LOOH is reductively detoxified by the action of glutathione peroxidase 4 (GPX4) or peroxiredoxin 6 (PRDX6). The hydrolytic removal of LOOH from P-LOOH by calcium-independent phospholipase A2 leads the preservation of membrane structure. While the expression of such protective genes or the presence of these anti-oxidant compounds serve to maintain a healthy condition, tumor cells employ them to make themselves resistant to anti-tumor treatments. Thus, these defense mechanisms against ferroptosis are protective in ordinary cells but are also potential targets for cancer treatment. [ABSTRACT FROM AUTHOR]

The formation of new carbon–nitrogen bonds is indisputably one of the most important tasks in synthetic organic chemistry. Here, nitroso compounds offer a highly interesting reactivity that complements traditional amination strategies, allowing for the introduction of nitrogen functionalities via ene-type reactions or Diels–Alder cycloadditions. In this study, we highlight the potential of horseradish peroxidase as biological mediator for the generation of reactive nitroso species under environmentally benign conditions. Exploiting a non-natural peroxidase reactivity, in combination with glucose oxidase as oxygen-activating biocatalyst, aerobic activation of a broad range of N-hydroxycarbamates and hydroxamic acids is achieved. Thus both intra- and intermolecular nitroso-ene as well as nitroso-Diels–Alder reactions are performed with high efficiency. Relying on a commercial and robust enzyme system, the aqueous catalyst solution can be recycled over numerous reaction cycles without significant loss of activity. Overall, this green and scalable C–N bond-forming strategy enables the production of allylic amides and various N-heterocyclic building blocks utilizing only air and glucose as sacrificial reagents. [ABSTRACT FROM AUTHOR]

Nitrosamines occur widespread in food, drinking water, cosmetics, as well as tobacco smoke and can arise endogenously. More recently, nitrosamines have been detected as impurities in various drugs. This is of particular concern as nitrosamines are alkylating agents that are genotoxic and carcinogenic. We first summarize the current knowledge on the different sources and chemical nature of alkylating agents with a focus on relevant nitrosamines. Subsequently, we present the major DNA alkylation adducts induced by nitrosamines upon their metabolic activation by CYP450 monooxygenases. We then describe the DNA repair pathways engaged by the various DNA alkylation adducts, which include base excision repair, direct damage reversal by MGMT and ALKBH, as well as nucleotide excision repair. Their roles in the protection against the genotoxic and carcinogenic effects of nitrosamines are highlighted. Finally, we address DNA translesion synthesis as a DNA damage tolerance mechanism relevant to DNA alkylation adducts. [ABSTRACT FROM AUTHOR]

The successful use of 1,3,4,2-triazaphospholenes (TAPs) as organo-catalysts stresses the need for efficient synthetic routes to these molecules. In this study, we establish the [1 + 4]-cycloaddition of PBr3 to azo-pyridines as a new approach to preparing pyrido-annellated TAPs in a single step from easily available precursors. The modular assembly of the azo-component via condensation of primary amines and nitroso compounds along with the feasibility of post-functionalization at the P–Br bond under conservation of the heterocyclic structure allows, in principle, to address a wide range of target molecules, which is illustrated by prototypical examples. The successful synthesis of a transition metal complex confirms for the first time the ability of a TAP to act as a P-donor ligand. Crystallographic studies suggest that hyperconjugation effects and intermolecular interactions induce a qualitatively similar ionic polarization of the P–Br bonds in TAPs as in better known isoelectronic diazaphospholenes. [ABSTRACT FROM AUTHOR]

Subsequent to the dietary uptake of nitrate/nitrite in combination with acetaldehyde/ethanol, combination effects resulting from the sustained endogenous exposure to nitrite and acetaldehyde may be expected. This may imply locoregional effects in the upper gastrointestinal tract as well as systemic effects, such as a potential influence on endogenous formation of N-nitroso compounds (NOC). Salivary concentrations of the individual components nitrate and nitrite and acetaldehyde are known to rise after ingestion, absorption and systemic distribution, thereby reflecting their respective plasma kinetics and parallel secretion through the salivary glands as well as the microbial/enzymatic metabolism in the oral cavity. Salivary excretion may also occur with certain drug molecules and food constituents and their metabolites. Therefore, putative combination effects in the oral cavity and the upper digestive tract may occur, but this has remained largely unexplored up to now. In this Guest Editorial, published evidence on exposure levels and biokinetics of nitrate/nitrite/NOx, NOC and acetaldehyde in the organism is reviewed and knowledge gaps concerning combination effects are identified. Research is suggested to be initiated to study the related unresolved issues. [ABSTRACT FROM AUTHOR]

The structure and bonding of H2NNO, the simplest N-nitrosamine, and a key intermediate in deNOx processes, have been precisely characterized using a combination of rotational spectroscopy of its more abundant isotopic species and high-level quantum chemical calculations. Isotopic spectroscopy provides compelling evidence that this species is formed promptly in our discharge expansion via the NH2 + NO reaction and is collisionally cooled prior to subsequent unimolecular rearrangement. H2NNO is found to possess an essentially planar geometry, an NNO angle of 113.67(5)°, and a N—N bond length of 1.342(3) Å; in combination with the derived nitrogen quadrupole coupling constants, its bonding is best described as an admixture of uncharged dipolar (H2N—N=O, single bond) and zwitterion (H2N+=N—O-, double bond) structures. At the CCSD(T) level, and extrapolating to the complete basis set limit, the planar geometry appears to represent the minimum of the potential surface, although the torsional potential of this molecule is extremely flat. [ABSTRACT FROM AUTHOR]

Background: Nitrosatable drugs commonly prescribed during pregnancy can react with nitrite to form N-nitroso compounds which have been associated with an increased risk of stillbirth. Whether maternal residential drinking water nitrate modifies this association is unknown. We investigated, if household drinking water nitrate was associated with stillbirth, and if it modified the association between nitrosatable prescription drug intake and the risk of stillbirth.Methods: We conducted an individual-level register- and population-based cohort study using 652,810 women with the first recorded singleton pregnancy in the Danish Medical Birth Registry between 1997 and 2017. Nitrosatable drug exposure was recorded by use of the Danish National Patient Registry defined as women with a first redeemed prescription of a nitrosatable drug the first 22 weeks of pregnancy. The reference group was women with no redeemed prescription of a nitrosatable drug in this period. The average individual drinking water nitrate concentration level (mg/L) was calculated in the same period. We categorized nitrosatable drugs as secondary amines, tertiary amines, and amides. Cox hazard regression was used to estimate crude and adjusted hazard ratios with 95% confidence intervals for stillbirth stratified into five categories of nitrate concentrations: ≤1 mg/L, > 1- ≤ 2 mg/L, > 2- ≤ 5 mg/L, > 5- ≤ 25 mg/L, and > 25 mg/L.Results: Drinking water nitrate exposure in the population was not associated with the risk of stillbirth. Among 100,244 women who had a nitrosatable prescription drug redeemed ≤22 weeks of pregnancy of pregnancy, 418 (0.42%) had a stillbirth compared to 1993 stillbirths (0.36%) among 552,566 referent women. Women with any nitrosatable prescription drug intake and > 1- ≤ 2 mg/L nitrate concentration had an increased risk of stillbirth [adjusted hazard ratio 1.55 (95% confidence interval, 1.15-2.09)] compared with referent women. In the stratified analyses, the highest risk of stillbirth was found among women with secondary amine intake and > 25 mg/L nitrate concentrations [adjusted hazard ratio 3.11 (95% CI, 1.08-8.94)].Conclusions: The association between nitrosatable prescription drug intake and the risk of stillbirth may depend on the level of nitrate in household drinking water. Evaluations of the effect of nitrosatable drug intake on perinatal outcomes might consider nitrate exposure from drinking water. [ABSTRACT FROM AUTHOR]

The research has proved the practical importance of using a biopolymer complex of thermostable animal proteins with functional and technological properties as a component of restructured ham-type products. It has been established that the water-holding and fat-holding capacity and the stabilising power of meat products significantly increase due to the introduction of the biopolymer complex developed by the authors, which contains sodium caseinate, buttermilk powder, and blood plasma Vepro 75 PSC. The experiments have confirmed that a protein-infat emulsion based on a biopolymer complex of thermostable animal proteins, a protein stabiliser obtained from turkey skin, and pork and turkey fats can be used as a component of restructured ham-type products from PSE pork and turkey meat. Thus, 5, 10, 15, and 20% of the proteinin-fat emulsion added to the formulations of restructured hams from lowfat pork and turkey meat increase the water-holding capacity of model meat systems by 7.49–9.05%, and their fat-holding capacity by 8.11–9.32%. Regular patterns have been established in how the stability of the functional and technological properties of the protein-infat emulsion changes throughout storage, depending on the nature and the content of a protein preparation (Vepro 75 PSC, sodium caseinate, buttermilk) and on the fat composition. It has been proved that the introduction of a protein-in-fat emulsion into the composition of hams allows obtaining products with improved and persistently high consumer properties. It has been confirmed that 0.35% of powdered sweet potato juice, in the presence of 0.025% of the starter culture of Staphylococcus carnosus, can be included in the composition of restructured ham-type products from PSE and turkey meat to colour them rosy-red, thus making it unnecessary to use sodium nitrite, a hazardous chemical. Sweet potato juice powder used in the presence of 0.025% of Staphylococcus carnosus has been found to reduce the residual amount of sodium nitrite to 3.10– 3.11 mg/100 g, because nitrate transforms into nitroso compounds more completely. The results of the study are of practical significance and will be helpful in expanding the range of restructured ham-type products of enhanced nutritional value. [ABSTRACT FROM AUTHOR]

The acyl nitroso Diels–Alder reaction of 1,3‐dienes with electrochemically oxidised hydroxamic acids is described. By using alternating current electrolysis, their typical electro‐induced decomposition could be suppressed in favour of the 1,2‐oxazine cycloaddition products. The reaction was optimised using Design of Experiments (DoE) and a sensitivity test was conducted. A mixture of triethylamine/hexafluoroisopropanol served as supporting electrolyte in dichloromethane, thus giving products of high purity after evaporation of the volatiles without further purification. The optimised reaction conditions were applied to various 1,3‐dienes and hydroxamic acids, giving up to 96 % isolated yield. [ABSTRACT FROM AUTHOR]

In the presence of Na2 CO3 , conjugate addition of α-halo hydrazones to nitroso compounds proceeded readily to give polyfunctionalized nitrones in reasonable chemical yields and excellent stereoselectivities. The chemical structure and the stereochemical configuration of the products were unambiguously identified by an X-ray single-crystal structural analysis. [ABSTRACT FROM AUTHOR]

A nitroso Diels–Alder (NDA) reaction between cyclopentadiene and an in situ generated nitroso compound leads to a new heterocyclic monomer for ring opening metathesis polymerization (ROMP) reactions. This monomer could be polymerized in the presence of Grubbs‐third generation initiator with good control over Mn and decent Ð values. The resulting isoxazolidine‐containing material could undergo further hydrogenation, deprotection, and modification with Dansyl chloride as well as ring opening to provide an amino‐and hydroxyl‐decorated "polyolefin." [ABSTRACT FROM AUTHOR]

We studied different approaches to the synthesis of polyfluoroalkyl-containing 1-methyl-4-nitrosopyrazoles, which are based on the cyclization of 4,4,4-trifluoro-3,3-dihydroxy-2-hydroxyimino-1-R-butan-1-ones or 2-hydroxyimino-1,3-diketones with methylhydrazine and on a one-pot sequential treatment of 1,3-diketones with sodium nitrite and methylhydrazine. It was found that the regioselectivity of the formation of 1-methyl-4-nitrosopyrazoles is affected by the steric factors of 1,3-dicarbonyl reagents. The study of the mycostatic effect of 4-nitrosopyrazoles showed that the introduction of a bulky polyfluoroalkyl or tert-butyl substituent leads to a decrease in their activity. [ABSTRACT FROM AUTHOR]

The challenges faced in the activation and functionalization of C−H bonds while producing high‐value aromatic intermediates are significant for synthetic organic chemistry. This review summarizes the advancements made toward the C−H functionalization of N‐nitrosoanilines in the past decade, in which the nitroso group coordinates to a transition metal, such as rhodium, palladium, cobalt, iridium, and ruthenium, acting as a directing group to allow the activation of the ortho C−H bond. The versatility of this synthetic approach has led to the regio‐ and chemoselective introduction of various functional groups giving rise to aromatic congeners with diverse functional and structural properties. C−H functionalized nitroso compounds can be further transformed into valuable synthetic intermediates and unique heterocyclic compounds. A description of the mechanism underlying each reaction is also included. This review includes the following sections: [ABSTRACT FROM AUTHOR]

An atom‐economic intermolecular radical addition reaction of acyloxy nitroso compounds to electron‐deficient alkenes mediated by visible light is reported. The starting nitroso derivatives are readily prepared by oxidation of the corresponding oximes prepared from ketones and the overall transformation represents an oxidative coupling of a ketone with a Michael acceptor. The cascade proceeds smoothly under mild conditions, providing a series of valuable functionalized oximes in moderate to good yields. Mechanistic studies suggest that these cascades proceed via addition/coupling processes that are controlled by the persistent radical effect (PRE) with NO acting as the persistent species. [ABSTRACT FROM AUTHOR]

Beetroot juice (BRJ) has become increasingly popular amongst athletes aiming to improve sport performances. BRJ contains high concentrations of nitrate, which can be converted into nitric oxide (NO) after consumption. NO has various functions in the human body, including a vasodilatory effect, which reduces blood pressure and increases oxygen- and nutrient delivery to various organs. These effects indicate that BRJ may have relevant applications in prevention and treatment of cardiovascular disease. Furthermore, the consumption of BRJ also has an impact on oxygen delivery to skeletal muscles, muscle efficiency, tolerance and endurance and may thus have a positive impact on sports performances. Aside from the beneficial aspects of BRJ consumption, there may also be potential health risks. Drinking BRJ may easily increase nitrate intake above the acceptable daily intake, which is known to stimulate the endogenous formation of N-nitroso compounds (NOC's), a class of compounds that is known to be carcinogenic and that may also induce several other adverse effects. Compared to studies on the beneficial effects, the amount of data and literature on the negative effects of BRJ is rather limited, and should be increased in order to perform a balanced risk assessment. [ABSTRACT FROM AUTHOR]

To gain a deeper understanding of the formation of the synthetically important 3,6‐dihydro‐2H‐1,2‐oxazines, the 6‐endo‐trig cyclization of allenyl‐substituted hydroxylamines was experimentally investigated in detail employing a model compound. The solvent effect was moderate with respect to the rate, but crucial to suppress side‐product formation. Surprisingly, acids or bases had no big influence on the cyclization rate. With O‐deuterated allenyl hydroxylamine a high primary isotope effect was found, indicating that the proton transfer is crucial in the rate‐determining step. DFT calculations evidence that the allenyl‐substituted hydroxylamine is converted into an energetically similar zwitterionic intermediate with an allyl cation subunit. It cyclizes to the 1,2‐oxazine as the most stable species. Alternative pathways starting from the zwitterion were computationally investigated. Interestingly, it can also undergo a fragmentation to give a pentadiene derivative and a nitroso compound. The hetero Diels–Alder reaction of these components may also deliver the 1,2‐oxazine. To evaluate an alternative mechanistic scenario, calculations of the protonated allenyl‐substituted hydroxylamine were also performed. [ABSTRACT FROM AUTHOR]

Background: High dietary intake of nitrate and nitrite might increase the risk of type 1 diabetes. To our knowledge, no earlier prospective study has explored whether maternal dietary intake of nitrate and nitrite during pregnancy is associated with the risk of type 1 diabetes in the offspring.Objective: Our aim was to study association between maternal intake of nitrate and nitrite during pregnancy and the risk of islet autoimmunity and type 1 diabetes in the offspring.Design: Children born between 1997 and 2004 at Oulu and Tampere University Hospitals in Finland and carrying increased human leukocyte antigen (HLA)-conferred risk for type 1 diabetes were followed in the Type 1 Diabetes Prediction and Prevention (DIPP) study from 3 mo of age. Islet autoantibodies were screened at 3- to 12-mo intervals from serum samples. Of 4879 children, 312 developed islet autoimmunity and 178 developed type 1 diabetes during a 15-y follow-up. Maternal intake of nitrate and nitrite during the eighth month of pregnancy was assessed after birth using a validated self-administered FFQ. Cox proportional hazards regression was used for the statistical analyses.Results: Maternal intake of nitrate and nitrite during pregnancy was not associated with the child's risk of islet autoimmunity [nitrate: HR 0.99 (95% CI: 0.88, 1.11); nitrite: HR 1.03 (95% CI: 0.92, 1.15)] or type 1 diabetes [nitrate: HR 1.02 (95% CI: 0.88, 1.17); nitrite: HR 0.97 (95% CI: 0.83, 1.12)] when adjusted for energy (residual method), sex, HLA risk group, and family history of diabetes. Further adjustment for dietary antioxidants (vitamin C, vitamin E, and selenium) did not change the results.Conclusion: Maternal dietary intake of nitrate or nitrite during pregnancy is not associated with the risk of islet autoimmunity or type 1 diabetes in the offspring genetically at risk for type 1 diabetes. [ABSTRACT FROM AUTHOR]

Beetroot juice (BRJ) has become increasingly popular amongst athletes aiming to improve sport performances. BRJ contains high concentrations of nitrate, which can be converted into nitric oxide (NO) after consumption. NO has various functions in the human body, including a vasodilatory effect, which reduces blood pressure and increases oxygen- and nutrient delivery to various organs. These effects indicate that BRJ may have relevant applications in prevention and treatment of cardiovascular disease. Furthermore, the consumption of BRJ also has an impact on oxygen delivery to skeletal muscles, muscle efficiency, tolerance and endurance and may thus have a positive impact on sports performances. Aside from the beneficial aspects of BRJ consumption, there may also be potential health risks. Drinking BRJ may easily increase nitrate intake above the acceptable daily intake, which is known to stimulate the endogenous formation of N-nitroso compounds (NOC's), a class of compounds that is known to be carcinogenic and that may also induce several other adverse effects. Compared to studies on the beneficial effects, the amount of data and literature on the negative effects of BRJ is rather limited, and should be increased in order to perform a balanced risk assessment. [ABSTRACT FROM AUTHOR]

The [4+2]‐cycloadditions of α‐nitrosoalkenes with thiochalcones occur with high selectivity at the thioketone moiety of the dienophile providing styryl‐substituted 4H‐1,5,2‐oxathiazines in moderate to good yields. Of the eight conceivable hetero‐Diels–Alder adducts only this isomer was observed, thus a prototype of a highly periselective and regioselective cycloaddition has been identified. Analysis of crude product mixtures revealed that the α‐nitrosoalkene also adds competitively to the thioketone moiety of the thiochalcone dimer affording bis‐heterocyclic [4+2]‐cycloadducts. The experiments are supported by high‐level DFT calculations that were also extended to related hetero‐Diels–Alder reactions of other nitroso compounds and thioketones. These calculations reveal that the title cycloadditions are kinetically controlled processes confirming the role of thioketones as superdienophiles. The computational study was also applied to the experimentally studied thiochalcone dimerization, and showed that the 1,2‐dithiin and 2H‐thiopyran isomers are in equilibrium with the monomer. Again, the DFT calculations indicate kinetic control of this process. [ABSTRACT FROM AUTHOR]

β-Endorphin exerts a broad spectrum of physiological activity on mood, immune functions, pain management, reward effects, and behavioral stability. β-Endorphin is produced in certain neurons within the central and peripheral nervous system but also in the skin, especially in response to ultraviolet radiation. In the present study we have investigated the impact of visible blue light at λ = 453 nm (BL) on β-endorphin production of primary human skin keratinocytes (hKC) in-vitro as well as on systemic β-endorphin formation of whole-body exposed subjects in-vivo. We found that BL irradiation significantly enhanced both keratinocytic β-endorphin production of hKC cultures as well as systemic β-endorphin concentrations in light exposed healthy subjects. Interestingly, in hKC cultures elevated β-endorphin formation was paralleled by significantly increased levels of non-enzymatically generated nitric oxide (NO), whereas elevated systemic β-endorphin values of BL-exposed subjects were accompanied by enhanced systemic concentration of bioactive NO-derivates. These findings point to a pivotal role of NO in the molecular mechanism of the observed BL-induced effects, and indeed, exogenously applied NO was able to significantly enhance β-endorphin production in hKC cultures. Thus, our finding of BL-induced increases in systemic β-endorphin concentration in-vivo can be plausibly explained by an event sequence comprising 1.) BL-driven non-enzymatic formation of NO in the exposed skin tissue, 2.) systemic distribution of cutaneously produced NO in the form of bioactive nitroso compounds, 3.) a subsequent NO-dependent induction of β-endorphin synthesis in epidermal keratinocytes, and 4.) probably also a NO-dependent modulation of β-endorphin synthesis in specialized neurons within the central and peripheral nervous system. Image 1 • In addition to its essential role in vitamin D synthesis, the environmental factor sunlight, especially its ultraviolet (UV) fraction, also strongly affects the human psyche, e.g. by modulating the synthesis psychoactive mediators like β-endorphin. • Here we show for the first time with human skin keratinocyte cultures but also with whole-body-irradiated healthy volunteers that visible UV radiation-free blue light, which has a much lower risk for side effects than UV radiation, also can induce a significant increase in local as well as systemic production of β-endorphin. • The underlying mechanism comprises an enhanced local or systemic generation of nitric oxide (NO) via blue lightinduced decomposition of photo-labile NO derivates. • Thus, based on our findings, blue light might have a relevant clinical potential to serve as supportive measure in the therapy of several psychiatric disorders that might by modulated by β-endorphin. [ABSTRACT FROM AUTHOR]

In this study, a simple approach such as the electrodeposition of palladium on carbon paste electrode (CPE) can be used with success to catalyze the reduction of p‐Nitrophenol (p‐NP). The electrodeposition procedure was carried out using cyclic voltammetry in acidic media. All parameters that influence the shift and the current intensity of the cathodic peak of p‐NP were optimized. Interestingly, Pd/CPE can catalyze the reduction of p‐NP to intermediate nitroso derivative. Electrocatalytic behavior at Pd/CPE toward p‐NP reduction was evaluated using the cyclic voltammetry, linear voltammetry, and differential pulse voltammetry, always following the concentration‐dependent current variance to confirm that the peak under study corresponds to the p‐NP reduction. Moreover, the catalytic activity of the Pd/CPE toward p‐NP reduction was also investigated during the electrolysis process. All results showing that palladium modified carbon paste electrode is considered a high catalyst for p‐NP reduction, with a satisfactory ability to detect it in aqueous media. [ABSTRACT FROM AUTHOR]

It is imperative to learn new synthetic transformations to succeed in drug discovery and development. We report the substrate‐driven synthesis of β‐enaminones and N‐aryl pyrroles from indolizines and nitrosoarenes; aryl‐substituted indolizines lead to β‐enaminones in a regio‐ and diastereoselective manner, whereas alkyl‐substituted indolizines produce tetrasubstituted pyrroles. All products contain a pyridine unit, the second most abundant ring (after phenyl) in the FDA Orange Book. In both cases, the reactions proceed at room temperature without any catalyst. Moreover, both types of products can be obtained in one pot from commercial materials as well as at a gram scale. It is worthy of note that the regioselectivity of the β‐enaminones is inaccessible by the standard literature methods and their utility has been exemplified in the synthesis of diverse heterocycles. We have made every endeavor to put forward the corresponding reaction mechanisms based on thorough experimental work. [ABSTRACT FROM AUTHOR]

In the presence of Fe3+ cation, S-nitrosoglutathione (GSNO) loses the potency to inhibit catalase in the system containing hemoglobin (an NO trap) with iron chelator or -SH inhibitor (a "sulfhydric poison" Hg2+). In the absence of hemoglobin, the inhibitory potency is retained in both cases. These properties are characteristic of dinitrosyl-iron complexes containing ferrous iron and thiols (DNIC/RSH). Since the potency to inhibit catalase results from the presence of -NO group, its loss in the presence of hemoglobin relates probably to transfer of this group to hemoglobin. The nitrosothiols are relatively stable compounds, so their ability to release NO under the action of iron chelators, which is characteristic of DNIC/RSH, can have important physiological implications, because the role of such chelators can be played by some endogenous agents as well. Thus, release of NO from the donor compounds can be controlled and regulated. Probably, the agents such as nitrosothiol+Fe3+ are the major constituents in the pool of nitroso compounds. [ABSTRACT FROM AUTHOR]

• A Quick Easy Cheap Effective Rugged Safe (QuEChERS) method resulted in best analyte recoveries. • Recovery efficiencies exceeded 89% for most target analytes in serum and urine. • Most analytes showed minimal matrix effects (between 80 and 120%) in both matrices. • QuEChERS is an advantageous alternative for pesticide analysis in serum and urine. In the acidic environment of the stomach, nitrosatable pesticide residues may react with nitrite to form potentially carcinogenic pesticide-associated N -nitroso compounds (PANOCs). The objective of this study was to develop a method for the analysis of 10 nitrosatable pesticides and breakdown products in human serum and urine. Three sample preparation methods were evaluated for extraction of target analytes from the biomatrices. Deproteinization by methanol for 300-μL aliquots of serum with a final extract volume of 225 μL resulted in excessive ion enhancement of some analytes and suppression of others. Three types of solid-phase extraction cartridges were tested for optimal analyte retention from 200-μL aliquots of serum with a final extract volume of 400 μL; this approach resulted in significant analyte loss for some compounds. The Quick, Easy, Cheap, Effective, Rugged, and Safe approach resulted in a suitable method for extraction of the analytes from each biomatrix. Biofluid samples (500 μL) were spiked to 100 μg L−1 with analytical standards and extracted using 500 μL of acetonitrile (ACN) with 4% acetic acid (AcOH) for serum and 0.1% AcOH in ACN for urine. For extraction, 200 mg magnesium sulfate (MgSO 4) and 50 mg sodium acetate were added for serum and 200 mg MgSO 4 and 50 mg sodium chloride were added for urine. Final extract volumes for both biomatrices using the QuEChERS method was 400 μL after dilution. Samples were analyzed via ultra-high pressure liquid chromatography/high-resolution accurate mass orbital ion trap mass spectrometry. Mean recoveries for target analytes in serum and urine ranged between 74 and 120% (%RSD < 12) and 96 to 116% (%RSD ≤ 10), respectively. These methods may be used in large-scale biomonitoring studies to analyze PANNs and their parent compounds in human serum and urine. [ABSTRACT FROM AUTHOR]

• A variety of organic nitric oxide derivatives can act as ligands. • Nitrosoarenes can display redox activity as ligands. • Azodioxide complexes can display unusual coordination geometry. • The coordination chemistry of nitroso compounds is relevant to toxicology. Organic derivatives of nitric oxide can serve as ligands for transition metals in a variety of fashions. This review surveys recent developments in the coordination chemistry of four main classes of organic NO derivatives: nitrosoalkanes and nitrosoarenes, azodioxides, and nitrosamines. Highlighted work includes evidence that nitrosoarenes can behave as redox-active ("non-innocent") ligands, an expansion in the number of crystallographically characterized azodioxide complexes, and the synthesis of N -bound primary nitrosamines. Relevance to the bioinorganic chemistry of metalloenzymes is noted. [ABSTRACT FROM AUTHOR]

Punicalagin and ellagic acid are the major polyphenols present in pomegranate peels. The contents of α‐punicalagin, β‐punicalagin, and ellagic acid in the pomegranate peels were approximately 75, 72, and 20 µM, respectively. The reactions of polyphenols in pomegranate peels with sodium nitrite under simulated stomach conditions were studied. The reactions decreased the polyphenolic contents of the pomegranate peels and accompanied the formation of nitroso compounds. The oxidation rates followed the order ellagic acid ＜α‐punicalagin ≈ β‐punicalagin. The results suggested that the reactions can occur in the stomach after a meal, while the pH changes from 2 to 4.5. [ABSTRACT FROM AUTHOR]

Low-lying relaxation satellites give rise to ultrafast electron dynamics following outer-valence ionization of a molecular system. To demonstrate the impact of such satellites, the evolution of the electronic cloud after sudden removal of an electron from the highest occupied molecular orbital (HOMO) of the organic unsaturated nitroso compound 2-nitroso[1,3]oxazolo[5,4-d][1,3]oxazole is traced in real time and space using ab initio methods only. Our results show that the initially created hole charge remains stationary but on top of it the system reacts by an ultrafast π-π* excitation followed by a cyclic excitation-de-excitation process which leads to a redistribution of the charge. The π-π* excitation following the removal of the HOMO electron takes place on a subfemtosecond time scale and the period of the excitation-de-excitation alternations is about 1.4 fs. In real space the processes of excitation and de-excitation represent ultrafast delocalization and localization of the charge. The results are analyzed by simple two- and three-state models. [ABSTRACT FROM AUTHOR]

The first n→π* transitions of 18 nitroso and 16 thiocarbonyl dyes have been computed by time-dependent density functional theory (TD-DFT) using pure as well as global and range-separated hybrid functionals. It turns out that the accuracy of all hybrids is relatively similar, i.e., the inclusion of a growing fraction of exact exchange does neither worsen nor improve significantly the raw TD-DFT estimations. However, after a simple linear regression, it appears that the range-separated hybrids provide a better accuracy than global hybrids. [ABSTRACT FROM AUTHOR]

N-nitroso compounds (NOCs) exposure is a major risk factor for the development of gastric cancer. However, the carcinogenic mechanisms by which NOCs induce gastric and other cancers, especially the NOCs-induced Warburg effect, have not been comprehensively studied. Lactate dehydrogenase (LDH), which has two subunits (LDHA and LDHB), plays an important role in the Warburg effect of tumor cells. Therefore, we hypothesized that LDHA and LDHB could promote Warburg effect in malignant transformed GES-1 cells induced by Nmethyl-N′-nitro-N-nitrosoguanidine (MNNG). GES-1 cells were exposed to 1 μmol/L MNNG and cultured for 40 passages. During the culturing process, cell proliferation, migration, and soft agar colony formation significantly increased after 30 passages. Following MNNG exposure, lactate, LDH, glucose uptake, and the expression levels of key enzymes in glycolysis were significantly increased. Knocking down LDHA or LDHB alone reduced lactate secretion, inhibited cell viability, and impaired migratory capacities. Knocking down LDHA and LDHB together fully suppressed lactate secretion and effectively suppressed the malignant phenotype of cells transformed by long-term MNNG exposure. Finally, we demonstrated that overexpression of LDHA and LDHB promotes the malignant transformation of GES-1 cells by enhancing the Warburg effect during long-term exposure to NOCs. • Long-tern MNNG exposure induced Warburg effect in GES-1 cells. • Both expression of LDHA and LDHB was increased in transformed GES-1 cells by MNNG. • LDHA and LDHB play an important role in Warburg effect of transformed GES-1 cells by MNNG. • MNNG have the potential binding sites with LDHA and LDHB. [ABSTRACT FROM AUTHOR]

A POM involving oxo-cerium and oxo-tungsten efficiently catalyzes the selective oxidation of aniline towards nitrosobenzene in water. [Display omitted] • Aniline is one of the most persistent pollutants in waste water effusing from the manufacturing of various industrial organic, including dyes, pesticides, rubber chemicals, and pharmaceuticals. It is highly toxic, mutagenic, and potentially fatal and can be regarded as a severe threat to humans and other creatures. But it can be converted into value-added chemicals under appropriate conditions, achieving to make the pollutant profitable. The conversion process proceeding in water is highly desirable and practical from both the elimination of pollutant in waste water and the production of value-added chemicals points of view. With the aim to realize the selective oxidation of aniline towards nitrosobenzene, one of the highly value-added products, in water, we have synthesized a {Ce 3 }-sandwiching POM catalyst K 10 Na 4 [Ce 3 (μ 2 -O) 3 (GeW 9 O 34) 2 ]·24H 2 O which possesses excellent stability in water and created a green system for the reaction. Experimental results show that the system can efficiently convert aniline towards nitrosobenzene selectively without any additives. Under optimized condition, aniline can be quantitatively converted and the selectivity towards nitrosobenzene reaches up to 82.9% without any additives. In the manuscript, following highlights are clearly presented. • Modulating the catalytic properties of the catalyst by incorporating rare-earth metal into POM skeleton. • Creating an effective system for the selective oxidation of aniline towards nitrosobenzene by using the water-soluble 1 as the catalyst without any phase transfer compounds and achieving quantitative conversion of aniline and high selectivity of 82.9% towards nitrosobenzene, which usually participates in further reaction and therefore leads to low selectivity under oxidative conditions. • The performance comparisons of different catalysts reveal that the structural combination of oxo-cerium and oxo-tungsten facilitates the enhancement of catalytic performance. • Water serves as the green solvent for the selective oxidation of aniline. The selective oxidation of aniline towards high value-added products in water is of great importance from both the elimination of aniline pollutant in water and the production of high value-added chemicals points of view. Herein, we report the synthesis and application of a {Ce 3 }-sandwiching germanotungstate K 10 Na 4 [Ce 3 (μ 2 -O) 3 (GeW 9 O 34) 2 ]·24H 2 O (1) in the selective oxidation of aniline and derivatives towards corresponding nitroso compounds in water with diluent H 2 O 2 as the oxidant. Compound 1 has been carefully characterized by X-ray single-crystal diffraction, TG, FT-IR, PXRD, XPS, and SEM. Under optimized condition, aniline can be quantitatively converted and the selectivity towards nitrosobenzene reaches up to 86.0% without any additives. The performance comparisons of different catalysts reveal that the structural combination of oxo-cerium and oxo-tungsten facilitates the enhancement of catalytic performance. [ABSTRACT FROM AUTHOR]

Studies scalar and angular correlations in CF[sub 3]NO photodissociation. Recoil speed distributions; Nitric oxide product rotational distributions; Potential energy surface on which photodissociation occurs; Statistical mechanism of photodissociation.

Abstract The problems of contamination of many products by nitroso compounds have been discussed since 1970′s and have been partially solved, namely, the contamination by carcinogenic volatile N-nitrosamines. However, there is still a gap in knowing non-volatile nitroso compounds in terms of both the determination of these compounds and the description of their toxicity. Therefore, a procedure for their detailed non-targeted study is necessary to be developed. Based on these facts, a new method permitting the detection and the classification of nitroso compound groups, such as N-nitroso, C-nitroso, and interfering substances in the nitrosamine specific chemiluminescence detection after previous gas chromatographic separation, was developed. The method is based on signal profiling of chromatographic peaks recorded by a chemiluminescence detector at different pyrolytic temperatures and subsequent multivariate chemometric classification. The resulting classification function by linear discriminant analysis shows good performance with total accuracy of 96.12% after the method validation. The method was successfully applied and demonstrated on a non-targeted beer sample analysis. Nitroso compounds detected by the method were selected for detailed structural analysis by GC-MS/MS. The combination of the presented method with the MS/MS instrumentation provides a really powerful analytical tool for the identification of unknown nitroso compounds in complex samples. This study represents a valuable contribution to the protocols of identification of organic compounds with the nitrogen functional groups – toxicologically and analytically important nitroso compounds. Graphical abstract Image 1 Highlights • The NCD method for selective discrimination of N- and C-nitroso compounds from other interfering compounds was developed. • Gas chromatography with chemiluminescence detection and chemometric discriminant analysis was used for this method. • Resulted classification model shows good performance with total accuracy of 96.12%. • The method is usable in non-targeted detection of nitroso compounds in complex samples. • In connection with MS/MS instrument, the method provides a highly valuable tool in nitroso compounds identification tasks. [ABSTRACT FROM AUTHOR]

Three types of organic solid‐state reactions, dimerizations, dissociations, and Z‐E isomerizations were investigated by using the transformations of aromatic C‐nitroso compounds in crystalline solids as a convenient molecular model. Here we propose a conceptual frame for solid‐state organic reaction mechanisms by examining activation parameters obtained from kinetic measurements under specific experimental conditions. The possibility of the appearance of a sort of short‐lived intermediate liquid phase that constitutes a critical condition for initiating chemical reaction in crystalline solids, similarly to the mechanism for the thermal solid‐state reactions proposed by Paul and Curtin is discussed. The analogy of the proposed concept with the recent hypothesis about the variable rigidity/softness of the reaction cavity in the enzyme reactions, and with the newest molecular dynamic simulation studies of solid phase transformations was considered. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A turn-on fluorescent probe for H 2 S has been developed. • The proposed probe employs a nitroso group as the recognition unit. • The proposed probe exhibits high selectivity, excellent sensitivity and rapid response for H 2 S. • The proposed probe can be used for fluorescence imaging of H 2 S in living cells. Abstract A turn-on fluorescent probe for hydrogen sulfide (H 2 S) employing flavylium derivative as the fluorophore and nitroso group as the recognition unit and was designed and synthesized. The free probe is almost non-fluorescent. Upon addition of H 2 S to the solution of the probe, its nitroso group was transformed to the corresponding amino group with fast reaction kinetics, affording a dramatic enhancement of fluorescence emission. The fluorescence intensity of the proposed probe at 625 nm showed a good linear with the concentration of NaHS over a range from 0 to 4 μM, with a limit detection of 29 nM (3δ). The proposed probe exhibited high selectivity, excellent sensitivity and rapid response (∼5 min) for H 2 S. Moreover, this probe was successfully used for fluorescence imaging of exogenous and endogenous H 2 S in living cells. [ABSTRACT FROM AUTHOR]

Abstract Carcinogenic effects in humans are ascribed to processed meat by organisations such as International Agency for Research on Cancer, World Cancer Research Fund and American Institute for Cancer Research. However, the term 'processed meat' covers a heterogenic group of products whose content of potential hazards differ considerably. To improve estimates of associations between processed meat intake and cancer risk we investigated ways to divide processed meat into subgroups that more precisely reflects its carcinogenic characteristics. We collected ingredient lists and declarations of salt content for >1000 processed meat products on the Danish market and combined the information with knowledge related to processing parameters. Some compounds that could affect the products' carcinogenic characteristics, alone or in combination, were evaluated and compared for 12 types of processed meat products, and we suggest subgrouping of processed meat with similar level of carcinogenic potential, which could improve the understanding of the cancer risk associated with processed meat intake in scientific human studies. [ABSTRACT FROM AUTHOR]

Abstract S -nitrosocaptopril (CapNO) possesses dual capacities of both Captopril and an NO donor with enhanced efficacy and reduced side effects. CapNO crystals are difficult to make due to its unstable S-NO bond. Here, we report a novel stable S -nitrosocaptopril monohydrate (CapNO·H 2 O) that is stabilized by intermolecular five-membered structure, where one H of H 2 O forms a hydrogen bond with O- of the stable resonance zwitterion Cap–S+=N–O-, and the O in H 2 O forms the dipole-dipole interaction with S+ through two unpaired electrons. With the chelation and common ion effect, we synthesized and characterized CapNO·H 2 O that is stable at 4 °C for 180 days and thereafter without significant degradation. Compared to Captopril, CapNO showed direct vasorelaxation and beneficial effect on PAH rats, and could be self-assembled in rat stomach when Captopril and NaNO 2 were given separately. This novel CapNO·H 2 O with low entropy paves an avenue for its clinical trials and commercialization. Graphical abstract fx1 Highlights • A surprisingly stable S -nitrosocaptopril monohydrate crystal was prepared. • The stability of S -nitrosocaptopril is greatly improved due to H 2 O molecules. • S -nitrosocaptopril monohydrate is a promising new candidate vasodilator. • A new delivery method for S -nitrosocaptopril self-assembly in vivo was established. [ABSTRACT FROM AUTHOR]

Highlights • New type of stereoisomers – rotamers of 5-nitrosopyrimidines were analyzed by CE. • 5-Nitrosopyrimidines form two rotamers stabilized by intramolecular hydrogen bonds. • Best CE separations of rotamers were achieved with β-CD or CM-β-CD stereoselectors. • Binding constants of 5-nitrosopyrimidines complexes with β-CD were estimated by CE. Abstract For the first time, capillary electrophoresis has been successfully employed for the fast and highly efficient separations of a novel type of stereoisomers – planar rotamers (planamers) of four newly synthesized 5-nitrosopyrimidine derivatives. These derivatives can form two rotamers differing in the orientation of nitroso group due to strong intramolecular hydrogen bonds. Partial separation of rotamers of two 5-nitrosopyrimidines was achieved in alkaline 50 mM sodium tetraborate, pH 9.3, and in acidic 18.5/42 mM Tris/phosphate, pH 2.3, background electrolytes (BGEs) free of stereoselectors. To improve the separation of these rotamers and to attain the baseline or better separation of rotamers of other two 5-nitrosopyrimidines, various BGEs and different cyclodextrins-based stereoselectors were tested. The most effective, i.e. the fastest and baseline or better separations of rotamers of all analyzed 5-nitrosopyrimidines were achieved within a short time, 3.7–9.3 min, in the above alkaline or acidic BGEs using β-cyclodextrin (β-CD) or carboxymethyl-β-CD as stereoselectors. Moreover, since the experiments with β-CD resulted in good separations of rotamers of all the investigated 5-nitrosopyrimidines, the apparent binding constants of their complexes with this selector were determined from the dependence of their effective mobilities on the β-CD concentration in the BGEs. The examined complexes were found to be relatively weak, with the apparent binding constants in the range 11.3–153.0 L/mol. [ABSTRACT FROM AUTHOR]