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A series of sulfosuccinate esters of cyclic alcohols was synthesized and we studied their effect on the kinetics of methane hydrate formation in high-pressure autoclaves. The effects of the structure of these compounds on foaming, induction time, and water-to-hydrate conversion were considered in comparison with sodium dodecyl sulfate. The preparation of these compounds was presented in detail. An increase in size of the cyclic fragment from C5 to C7 leads to some increase in the rates of nucleation and growth of the methane hydrate, while going to an eight-membered carbon ring leads to a decrease in the promotion effect. The effect of the synthesized compounds on the increase in rate of gas hydrates is comparable to the effect for sodium dodecyl sulfate. At the same time, the proposed reagents possess better performance characteristics (do not contribute to foaming). [ABSTRACT FROM AUTHOR]

[Display omitted] • The first regioselective palladium(II)-catalyzed alkoxy-aryloxycarbonylation of olefins is described. • Various olefins, alcohols and phenols have been converted into the corresponding mixed alkyl-aryl succinates in one-step, with yields up to 90%, under mild reaction conditions (4 bar of CO and 20 °C). • The selectivity of the process has been explained by means of DFT calculations. • The unexpected role of the oxidant benzoquinone, in promoting the final elimination step leading to the succinic product, has been identified. The direct alkoxy-aryloxycarbonylation reaction of olefins has been realized for the first time. Under palladium(II) catalysis and with p -benzoquinone as oxidant, various olefins (aromatic, aliphatic and 1,2-disubstituted), alcohols (primary, secondary and tertiary) and phenols (with different para , meta and ortho substituents) have been converted in one-step into mixed alkyl aryl succinates in moderate to excellent yields (up to 90%). The reaction is completely regioselective, as the aryl ester moiety was consistently observed on the more substituted carbon of the starting alkene double bond. Based on experimental results and detailed DFT calculations, a plausible catalytic cycle has been proposed, accounting for the observed regioselectivity. Interestingly, from our computation studies, benzoquinone was found to be crucial not only to regenerate the catalytic active species, but also for promoting the final elimination step, leading to the desired succinate. Finally, some reactions were performed to prove the different chemical behavior of the two installed ester groups. [ABSTRACT FROM AUTHOR]

The synthesis of dibenzyl-(1S*,2S*)-2,3-dihydro-1H-indene-1,2-dicarboxylate has been realized through a diastereospecific bis-alkoxycarbonylation reaction, which starts from the cheap and easily available 1H-indene, benzyl alcohol, and carbon monoxide. The catalyst is formed in situ by mixing Pd(TFA)2, the ligand N2,N3-bis(2,6-dimethylphenyl)butane-2,3-diimine, p-benzoquinone is used as an oxidant, and benzyl alcohol acts both as a nucleophile and as the main solvent. [ABSTRACT FROM AUTHOR]

The use of natural gas as an energy source is increasing significantly due to its low greenhouse gas emissions. However, the common methods of natural gas storage and transportation, such as liquefied or compressed natural gas, are limited in their applications because they require extreme conditions. Gas hydrate technology can be a promising alternative to conventional approaches, as artificially synthesized hydrates provide an economical, environmentally friendly, and safe medium to store energy. Nevertheless, the low rate of hydrate formation is a critical problem that hinders the industrial application of this technology. Therefore, chemical promoters are being developed to accelerate the kinetics of gas hydrate formation. In this paper, the effect of new sodium sulfosuccinate compounds, synthesized based on glycerol and pentaerythritol, on methane hydrate formation was studied. Experiments under dynamic conditions using high-pressure autoclaves demonstrated that the conversion of water-to-hydrate forms increased from 62 ± 5% in pure water to 86 ± 4% for the best promoter at concentration 500 ppm. In addition, the rate of hydrate formation increases 2–4 times for different concentrations. Moreover, none of the synthesized reagents formed foam, compared to sodium dodecyl sulfate, in which the foam rate was 3.7 ± 0.2. The obtained reagents showed good promotional properties and did not form foam, which makes them promising promoters for gas hydrate technology. [ABSTRACT FROM AUTHOR]

Background: Dipeptidyl peptidase-4 inhibitors (DPP-4Is) are used clinically as oral antidiabetic agents. Although DPP-4Is are known to ameliorate liver fibrosis, the protective mechanism of DPP-4Is in liver fibrosis remains obscure. In this study, gemigliptin was used to investigate the potential of DPP-4Is to alleviate the progression of liver fibrosis. Methods: To clarify the effects and mechanisms of gemigliptin, we conducted various experiments in LX-2 cells (immortalized human hepatic stellate cells [HSCs], the principal effectors of hepatic fibrogenesis), which were activated by succinate and exhibited elevated expression of α-smooth muscle actin, collagen type 1, and pro-inflammatory cytokines and increased cell proliferation. In vivo, we examined the effects and mechanisms of gemigliptin on a high-fat, high-cholesterol--induced mouse model of nonalcoholic steatohepatitis (NASH). Results: Gemigliptin decreased the expression of fibrogenesis markers and reduced the abnormal proliferation of HSCs. In addition, gemigliptin reduced the succinate-induced production of mitochondrial reactive oxygen species (ROS), intracellular ROS, and mitochondrial fission in HSCs. Furthermore, in the mouse model of NASH-induced liver fibrosis, gemigliptin alleviated both liver fibrosis and mitochondrial dysfunction. Conclusion: Gemigliptin protected against HSC activation and liver fibrosis by alleviating mitochondrial dysfunction and ROS production, indicating its potential as a strategy for preventing the development of liver disease. [ABSTRACT FROM AUTHOR]

Succinic acid esters are important compounds that find many applications in various industrial fields. One of the most promising and easy ways of producing these molecules is represented by the bis-alkoxycarbonylation reaction of olefins. In particular, a recently developed catalytic system, consisting of an aryl α-diimine/palladium(II) catalyst and p-benzoquinone as an oxidant, has allowed succinates to be obtained in high yields. A similar methodology was applied here for the unprecedented synthesis of the bis(2-hydroxyethyl) 2-phenylsuccinate in 78% isolated yield, starting from the cheap and commercially available compounds styrene and ethylene glycol. To our knowledge, no other examples of bis-alkoxycarbonylations of olefins involving diols have been reported thus far. The obtained product was fully characterized by NMR and ESI-MS analyses. [ABSTRACT FROM AUTHOR]

Carotenoid succinates were synthesized from hydroxy carotenoids and were coupled to a commercially available derivative of melatonin via amide bond for producing more powerful anti-oxidants and yet new hybrid lipophilic bifunctional molecules with additional therapeutic effects. The coupling reactions produced conjugates in acceptable to good yields. Succinylation increased the water solubility of the carotenoids, while the conjugation with melatonin resulted in more lipophilic derivatives. The conjugates showed self-assembly in aqueous medium and yielded relatively stable colloidal solutions in phosphate-buffered saline. Antioxidant behavior was measured with ABTS and the FRAP methods for the carotenoids, the carotenoid succinates, and the conjugates with melatonin. A strong dependence on the quality of the solvent was observed. TEAC values of the new derivatives in phosphate-buffered saline were found to be comparable to or higher than those of parent carotenoids, however, synergism was observed only in FRAP assays. [ABSTRACT FROM AUTHOR]

[Display omitted] • The earth-abundant and cost-efficient CoCl 2 was employed to afford 1,4-dicarboxylic acid diesters under mild conditions. • The novel ligand (BiPyPhos) is the key to success. • This methodology features 100% atomic efficiency, time-saving, and acid-free. • The reaction affords the desired product directly, and an associative mechanism is proposed. Herein, we report a straightforward approach to access 1,4-dicarboxylic acid diesters via BiPyPhos-enabled cobalt-catalyzed bis-alkoxycarbonylation of alkynes. This strategy utilizes an earth-abundant and cost-efficient cobalt catalyst, free from acid additives or noble metal catalysts. The bifunctional ligand BiPyPhos plays a crucial character in both the rate-determining step and the stability of the cobalt catalytic system. The reaction delivers the product directly with an associative abstraction process. Mechanism studies coupled with NMR, FI-IR, HRMS, and single-crystal X-ray analysis indicate that the carbonyl cobalt hydride complex might be the catalytically active species. Utilizing CoCl 2 for bis-alkoxycarbonylation of alkynes has hardly any precedent. [ABSTRACT FROM AUTHOR]

A chemoselective method for the carbonylation of allylic substrates CH2=CHCH2X (X=OAc, OC(O)CH2CN, OPh, OEt, OC(O)OPh, OC(O)OiBu, N(H)C(O)Ph, N(Ph)C(O)Ph, N(H)Boc, N(Ph)Boc, Ph, CO2Bn, CN), leading to alkyl succinates with preservation of the X group, under Pd(II)‐catalyzed oxidative carbonylation conditions, has been developed. Our method shows a completely different inverse chemoselectivity with respect to the "classical" substitutive carbonylation of the allyl compounds, which is known to provide β,γ‐unsaturated carbonyl derivatives through the formation of a π‐allylpalladium intermediate. An accurate study, carried out using allyl acetate as model substrate, allowed to maximize the selectivity in the envisioned 2‐CH2X substituted succinates. The best catalyst is generated in situ by mixing Pd(TFA)2 (TFA=trifluoroacetate) and the N,N′‐di(anthracen‐9‐yl)butane‐2,3‐diimine ligand. p‐Benzoquinone was used as oxidant in presence of benzyl alcohol, which acts as a nucleophile and as a solvent, under 4 bar of CO at 20 °C. A combined effect of the ligand and the nucleophile, rationalized through DFT calculations, has been observed both in promoting the bis‐alkoxycarbonylation process and in preventing π‐allylpalladium‐mediated side reactions, allowing the attainment of succinate derivatives with moderate to good yields. [ABSTRACT FROM AUTHOR]

An efficient and convenient three-component reaction of dialkyl acetylene dicarboxylates with trialkyl(aryl) phosphites in the presence of maleimide or phthalimide provides a straightforward approach to the synthesis of stable dialkyl(aryl) phosphoryl succinates in excellent yields. While the reactions were carried out in the presence of triphenylphosphine, stabilized phosphoranes, obtained from three component reaction, undergo a smooth intramolecular Wittig reaction in boiling toluene to produce functionalized 2H-pyrrol-2-ones in good yields. [ABSTRACT FROM AUTHOR]

SUCNR1 is an auto- and paracrine sensor of the metabolic stress signal succinate. Using unsupervised molecular dynamics (MD) simulations (170.400 ns) and mutagenesis across human, mouse, and rat SUCNR1, we characterize how a five-arginine motif around the extracellular pole of TM-VI determines the initial capture of succinate in the extracellular vestibule (ECV) to either stay or move down to the orthosteric site. Metadynamics demonstrate low-energy succinate binding in both sites, with an energy barrier corresponding to an intermediate stage during which succinate, with an associated water cluster, unlocks the hydrogen-bond-stabilized conformationally constrained extracellular loop (ECL)-2b. Importantly, simultaneous binding of two succinate molecules through either a "sequential" or "bypassing" mode is a frequent endpoint. The mono-carboxylate NF-56-EJ40 antagonist enters SUCNR1 between TM-I and -II and does not unlock ECL-2b. It is proposed that occupancy of both high-affinity sites is required for selective activation of SUCNR1 by high local succinate concentrations. [Display omitted] • SUCNR1 attracts and binds succinate through a cluster of arginines around TM-VI • The arginines constitute two low-energy succinate binding sites • SUCNR1 is activated by simultaneous binding of two succinates at high concentrations • Binding of succinate, but not antagonist, unlocks constrained ECL-2 via water cluster Extracellular succinate is an auto- and paracrine metabolic stress signal sensed by SUCNR1. Using MD simulations, Shenol et al. found that SUCNR1 has two low-energy binding sites, and its selective activation by high, local concentrations of succinate requires simultaneous occupancy of both high-affinity sites. [ABSTRACT FROM AUTHOR]

Background. The study of surface activity, micelle formation, phase behavior and the identification of the nature of the structure of aggregates in solutions of surfactants with a double lipophilic chain is urgent. The study of the micelle-forming ability and phase behavior of surfactants is of practical importance, because their use in many industries is associated with the properties of micellar solutions. Purpose. Investigation of the surface activity and micelle-forming ability of the sodium salt of hexyl ester of decilensuccinic acid (D-12) and the phase behavior of the binary system AD-12 / water, the structure of aggregates in this system. Methodology. The critical micelle concentration was determined using the data on the surface tension of surfactant solutions. The phase state of the binary system was determined by visual observations and using a polarizing microscope. The type of liquid crystal was determined based on the microscopic texture. Originality. Due to the presence of hydrocarbon chains of the surfactant D-12, the lamellar liquidcrystalline phase prevails in a binary system with water on the phase diagram in a wide range. It was found that it coexists with water in the form of vesicles in the two-phase region of the phase diagram. Findings. A phase diagram of the D-12 / water binary system was obtained depending on the concentration of the components and the temperature of the system. At a surfactant concentration above the critical one, D-12 forms a normal micellar solution. At higher concentrations, D-12 molecules form lamellar liquid crystals. It was found that due to the double hydrocarbon chain of the D-12 molecule, the lamellar liquid crystal phase exists in a wide range of the phase diagram. It has been shown that, upon addition of water, the cross-sectional area of D-12 molecules in lamellar liquid crystals changes insignificantly, which is associated with the invariability of the distance between the lipophilic layers of liquid crystals. [ABSTRACT FROM AUTHOR]

Microbial ethylene-forming enzyme (EFE) converts the C3ÐC4 fragment of the ubiquitous primary metabolite 2-oxoglutarate (2OG) to its namesake alkene product. This reaction is very different from the simple decarboxylation of 2OG to succinate promoted by related enzymes and has inspired disparate mechanistic hypotheses. We show that EFE produces stereochemically random (equal cis and trans) 1,2-[2H2]-ethylene from (3S,4R)-[2H2]-2OG, appends an oxygen from O2 on the C1-derived (bi)carbonate, and can be diverted to w-hydroxylated monoacid products by modifications to 2OG or the enzyme. These results implicate an unusual radical-polar hybrid mechanism involving iron(II)-coordinated acylperoxycarbonate and alkylcarbonate intermediates. The mechanism explains how EFE accesses a high-energy carboxyl radical to initiate its fragmentation cascade, and it hints at capabilities of 2OG-dependent enzymes that may await discovery and exploitation. [ABSTRACT FROM AUTHOR]

BACKGROUND: A heavy load exercise may lead to skeletal muscle damage and the mitochondrial dysfunction. As an important treatment measure, acupuncture should play a certain role in the repair of injury. OBJECTIVE: To investigate the damage of skeletal muscle mitochondria in different phases after a heavy load exercise and acupuncture intervention, and further explore the role of acupuncture in preventing and treating exercise-induced skeletal muscle injury. METHODS: Male Sprague-Dawley rats were randomly divided into a control group, an acupuncture group, an exercise group and an exercise+acupuncture group. Among them, exercise and exercise+acupuncture groups performed a single bout heavy load exercise; and acupuncture and exercise+acupuncture groups performed acupuncture intervention. The acupuncture, exercise and exercise+acupuncture groups were further divided into 0, 2, 6, 12, 24, 48, and 72 hours groups according to the time points of sampling after the intervention. The ultrastructural changes of skeletal muscle mitochondria were observed by transmission electron microscopy. The fluorescence ratio of JC-1 was detected by fluorescent enzyme labeling technique. The content of cytoplasmic cytochrome C and mitochondrial function index, the activity of succinate ubiquinone oxidoreductase, were determined by ELISA. RESULTS AND CONCLUSION: After exercise, the mitochondrial ultrastructure was obviously damaged (severest at 12-24 hours), the cytoplasmic cytochrome C content was increased (P < 0.05), and the JC-1 ratio and succinate ubiquinone oxidoreductase activity were decreased (P < 0.05). The mitochondria were normal after acupuncture, and there was no significant changes in each test index (P > 0.05). Acupuncture intervention decreased the ultrastructural damage of skeletal muscle mitochondria, reduced the cytoplasmic cytochrome C content (P < 0.05), and increased the JC-1 ratio and succinate ubiquinone oxidoreductase activity (P < 0.05). To conclude, after a bout of eccentric exercise, the mitochondria have different degrees of damage and temporal changes, which peak from 12 to 24 hours. Acupuncture alone cannot cause obvious damage of skeletal muscle mitochondria. Acupuncture intervention can effectively improve mitochondrial damage caused by exercise and promote the recovery of mitochondrial function after exercise. [ABSTRACT FROM AUTHOR]

The design of the hierarchical structure and geometry of nanomaterials at the molecular and macroscopic level are crucial to determine their properties and applications. In this work, we describe a facile and effective method to control over the mesostructure and morphology of ethane-bridged PMOs with the assistance of various organic salts under basic conditions. It is demonstrated that the specific interaction between the surfactant and organic salts is responsible for the shape of surfactant micelles and the formation of ethane-bridged PMOs. Specifically, the structure and the hydrophobicity of the organic salts play a major role. The addition of organic salts with more hydrophobic organic moieties, such as sodium salicylate, sodium succinate and sodium benzoate, will increase the surfactant packing parameter more effectively, leading to the mesophase change from cubic Pm3n to 2-D hexagonal P6mm structure, whereas the addition of organic salts with lower hydrophobicity and larger polar head, like sodium oxalate, will result in the mesophase transformation from cubic Pm3n to 3-D hexagonal P63/mmc structure. Moreover, the addition of organic salts will not only affect the micellar formation, but also influence the charge matching at the surfactant/silicate interface as well as the condensation and aggregation kinetics of silica species. The addition of large amount of any organic salts will eventually lead to the formation of PMOs with disordered mesoporous structure. [ABSTRACT FROM AUTHOR]

Synthesis, IR spectroscopic and X-ray structural studies of crystals [UO2(C4H4O4)(C6H5NO2)2] (I) and a new modification [UO2(C4H4O4)(H2O)] (II), where C4H4O42– are succinate ions, and C6H5NO2 is isonicotinic acid. Structure I is formed by chains in which succinate ions play the role of bridging ligands Q02 and B2, and isonicotinic acid molecules in the form of a zwitterion are monodentate ligands M1. Chains I correspond to the crystal chemical formula АQ020.5B20.5M12, where = UO22+, Q02 and B2 = C4H4O42–, and M1 = C6H5NO2. The reasons of the change in the coordination type of half of the succinate ions in I from characteristic Q02 to rare B2 are explained from the standpoint of the 18-electron rule in uranyl compounds. Structure II, like the two already known modifications, corresponds to the crystal chemical formula АQ4M1, where A = UO22+, Q4 = C4H4O42–, and M1 = H2O. By the example of uranyl succinate monohydrate polymorphs, it was found that, like silica polymorphs, chemically identical 3D uranyl-containing frameworks can differ both in topology (reconstructive isomers) and in the symmetry of the framework (deformation isomers). It was found that the new γ-form of II in the region of ≈180 K reversibly transforms into the already known low-temperature β-modification. It was shown using the Voronoi–Dirichlet polyhedra, that the available data for the fourth polymorph [UO2(C4H4O4)(H2O)] registered in the CSD as {SUCCUR02}, are erroneous. [ABSTRACT FROM AUTHOR]

The objective of this study is to prepare zein/starch sodium octenyl succinate composite nanoparticles (ZSPs) via anti‐solvent precipitation technology and characterize their colloidal properties. The effects of polar solvents, ultrasonic treatment time, and concentrations of starch sodium octenyl succinate were investigated. We measured the particle size distribution, hydrophobicity, and apparent structures of the composite nanoparticles. Ultrasonic treatment time (0‐25 min) was found to play an important role in composite nanoparticle formation. The ZSP nanoparticles were with an average particle size in the range of 70 to 110 nm. When the ultrasonic treatment time exceeds 25 min, ZSPs became macroscopic particles. The fluorescence spectrum and three‐phase contact angle indicated that ZSPs presented hydrophilicity with largest three‐phase contact angle, which was 65.1°. Fourier transform infrared spectroscopy and scanning electron microscopy revealed that hydrophilic SSOS absorbed on the surface of zein nanoparticles via Van der Waals to improve their water solubility. The changes in solvent polarity and zein self‐assembly are considered to be the main driving force for composite nanoparticles conformational transitions from α‐helix to β‐sheet. Differential scanning calorimetry analysis indicated that ethanol combined ultrasonic treatment (10 min) was beneficial to enhance the thermal stability of composite nanoparticles, causing the highest Tg of 153.6°C. This work aims to provide a practical reference for formulating delivery systems using bioactive compounds containing zein as a carrier biopolymer. Practical Application: This work aims to provide a practical reference for formulating encapsulants for food and other bioactive compounds containing zein as a carrier biopolymer. Zein/starch sodium octenyl succinate composite nanoparticles formulated in this study provide novel stabilizers for emulsification systems or carriers of bioactive substances that can enhance the nutritional value, taste, or shelf life of foods. [ABSTRACT FROM AUTHOR]

Reactions of solid trihydroxopentaoxohexabismuth(III) pentanitrate trihydrate [Bi6O5(OH)3](NO3)5·3H2O and monoclinic bismuth oxide α-Bi2O3 with a succinic acid solution were studied with the aim of preparing a pharmaceutical substance, basic bismuth succinate С2Н4(СООBiO)2, meeting high purity requirements concerning the content of impurity metals. A procedure for preparing basic bismuth(III) succinate was suggested; it involves hydrolytic treatment of a process solution of bismuth in nitric acid to obtain high-purity [Bi6O5(OH)3](NO3)5·3H2O, its treatment with a NaOH solution to obtain finely crystalline α-Bi2O3, and the subsequent reaction of bismuth oxide with a succinic acid solution. The product composition was confirmed by X-ray diffraction, chemical analysis, IR and Raman spectroscopy, and thermal gravimetric analysis; the content of impurity metals was determined by the atomic absorption method. [ABSTRACT FROM AUTHOR]

A procedure was developed for preparing 2,3-dialkyl-substituted succinates by condensation of a succinic acid diester with two isobutyraldehyde molecules, followed by esterification and hydrogenation of the sum of dienes. Diethyl 2,3-diisobutylsuccinate of 75–99% purity was prepared by this procedure in a good yield. The use of the synthesized diethyl 2,3-diisobutylsuccinate as a stereoregulating component of titanium–magnesium catalysts allows synthesis of polypropylene with broad molecular-mass distribution. The catalysts prepared using >95% pure diethyl 2,3-diisobutylsuccinate have the best characteristics and allow preparation of polypropylene with high isotacticity index in a high yield. [ABSTRACT FROM AUTHOR]

BACKGROUND: In order to improve the stability of vitamin E and broaden its scope of application, an effective solution is to convert vitamin E into its derivatives. This work developed a new Candida rugosa lipase (CRL) nanogel based on modification of ionic liquid with vinyl functional groups. This novel CRL nanogel was used in the preparation process of vitamin E succinate based on the principle of non‐aqueous enzymology. At the same time, various factors including enzyme concentration, substrate molar ratio, reaction temperature and reaction time, that affect the yield of vitamin E succinate were optimized and analyzed. RESULTS: Different solvents with various hydrophobicity parameters (LogP values) from −1.3 to 3.5 were studied, it was found that dimethyl sulfoxide (DMSO) had the lowest LogP value among organic solvents but vitamin E succinate had the highest yield in DMSO. Furthermore, the effect of different operating conditions, such as molar ratios of substrate, enzyme concentration, reaction temperature and reaction time was studied. Under the optimal process conditions (enzyme concentration 6 mg mL−1, substrate molar ratio 4:1, reaction temperature 55 °C and reaction time 15 h), the product yield was 62.58 ± 1.16%. CRL and CRL nanogel were characterized using Fourier‐transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). It was shown that CRL nanogel influenced the catalytic behavior of lipase significantly by changing the structure and surface properties of CRL. CONCLUSION: Novel lipase nanogel was an excellent biocatalyst for enzymatic synthesis of vitamin E succinate. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

During the glyoxylate cycle, isocitrate lyases (ICLs) catalyze the lysis of isocitrate to glyoxylate and succinate. Itaconate has been reported to inhibit an ICL from Mycobacterium tuberculosis (tbICL). To elucidate the molecular mechanism of ICL inhibition, we determined the crystal structure of tbICL in complex with itaconate. Unexpectedly, succinate and itaconate were found to bind to the respective active sites in the dimeric form of tbICL. Our structure revealed the active site architecture as an open form, although the substrate and inhibitor were bound to the active sites. Our findings provide novel insights into the conformation of tbICL upon its binding to a substrate or inhibitor, along with molecular details of the inhibitory mechanism of itaconate. [ABSTRACT FROM AUTHOR]

The reaction of alkyl 2-(bromozinc)acylates, obtained from ethyl bromoacetate (or butyl 2-bromobutanoate, or butyl 2-bromo-2-methylpropanoate) under the action of zinc, with N-chloro- or N-bromodiethylamine in tetrahydrofuran at 20–25°C under argon for 2 h resulted in the formation of diethyl succinate (or dibutyl 2,3-diethyl succinate, or dibutyl tetramethyl succinate) and diethylamine instead of the expected products of the nucleophilic substitution of the halogen with the 2-alkoxycarbonylalkyl residue. An anion-radical reaction mechanism was proposed. [ABSTRACT FROM AUTHOR]

The aim of the study. To evaluate the effect of succinic acid derivatives on changes of mitochondrial function in rats under cerebral ischemia conditions. Materials and methods. In this work, the effect of succinic acid, ethylmethylhydroxypyridine succinate, and acetylaminosuccinic acid at doses of 50 mg/kg, 100 mg/kg, and 200 mg/kg (per os) on the change of the neuronal mitochondria function was studied. Cerebral ischemia was reproduced by the Tamura method. The following parameters were evaluated: changes in aerobic/anaerobic metabolism, mitochondrial membrane potential, the opening rate of the mitochondrial pore of transitional permeability and the activity of apoptotic systems. Results. During the study, it was found that the use of the test-compounds at doses of 100 mg/kg and 200 mg/kg contributed to an increase in ATP-generating activity, as well as the maximum respiration level and respiratory capacity, while accompanied by a decrease in the intensity of anaerobic metabolism reactions. Also, upon administration of the test succinic acid derivatives, an increase in the mitochondrial membrane potential and latent opening time of the mitochondrial pore transitional permeability were observed. Moreover, the activity of caspase-3 and apoptosis-inducing factor on groups treated by test objects at doses of 100 mg/kg and 200 mg/kg was significantly lower than that in untreated animals. Conclusion. The studied succinic acid derivatives contribute to the restoration of mitochondrial function in cerebral ischemia conditions, while the most effective dose can be considered to be 100 mg/kg. [ABSTRACT FROM AUTHOR]

Using first-order derivative techniques, a simple accurate and precise Ultraviolet spectrophotometric method was developed for the determination of solifenacin succinate and tamsulosin hydrochloride in combined dosage form. Every solifinacin succinate and tamsulosin hydrochloride was scanned in the wavelength region of 200-400 nm for determination of sampling wavelengths and selected sampling wavelengths were selected. Sampling wavelengths were chosen at 265 nm (zero crossing of solifinacin succinate) where the absorbance of tamsulosin hydrochloride was important and at 250 nm (zero crossing of tamsulosin hydrochloride) where the absorbance of solifinacin succinate was significant. For solifenacin succinate, linearity ranged from 10 to 100 μg/ml with a correlation coefficient of 0.998 and 2 to 10 μg/ml for the correlation coefficient of tamsulosin hydrochloride is 0.9988. The median recovery was considered to be satisfactory. For the routine study of solifenacin succinate and tamsulosin hydrochloride in combined dosage forms, the approach proposed can be applied. [ABSTRACT FROM AUTHOR]

For more effective chemotherapy and targeted treatment of colorectal cancer, this study seeks to develop chitosan (CH)-human serum albumin (HAS)-D-α-tocopheryl polyethylene glycol 1000 (TPGS) nanoparticles (BOS-CH-HSA-TPGS-NPs) coated with Bosutinib (BOS). Nuclear magnetic resonance (NMR) indicated that chitosan's structure was modified by carbodiimide coupling with HSA. We used a Box-Behnken design to find the ideal region for particle size, zeta potential, and entrapment efficiency, eventually emerging at a formulation with these values: 187.14 ± 3.2 nm, 76.2 ± 0.96 %, and 21.1 ± 2.3 mV. Differential scanning calorimetry (DSC), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), High-performance liquid chromatography (HPLC) were all used to characterize the sample in detail. At a phosphate buffer pH of 7.4, in vitro drug release tests showed both Higuchi model release (0.954) and Fickian diffusion (n = 0.5). Compared to free BOS, HCT116 cell lines showed considerably higher cytotoxicity in in vitro cytotoxicity assays. In male albino Wistar rats, the BOS-CH-HSA-TPGS-NPs also showed enhanced pharmacokinetics, targeting efficiency, and biocompatibility. When used to the treatment of colorectal cancer, the BOS-CH-HSA-TPGS NPs show promise as a sustained-release therapy with improved therapeutic effects by addressing the challenges of poor solubility, poor permeability, and toxic side effects. [Display omitted] • Synthesized TPGS-coated CH-HSA carbodiimide-conjugated NPs encapsulating Bosutinib (BOS). • Analyzed material properties and process factors using Box-Behnken design for quality enhancement. • Utilized FTIR, XRD, SEM, AFM for characterization, assessed in-vitro drug release, and HCT116 cytotoxicity. • In-vivo rat study indicated superior targeting, colon-specific uptake, and biocompatibility. • Optimized BOS-CH-HSA-TPGS NPs exhibiting sustained in-vitro anti-cancer activity on HCT116 cells. [ABSTRACT FROM AUTHOR]

Key to the success of intracellular pathogens is the ability to sense and respond to a changing host cell environment. Macrophages exposed to microbial products undergo metabolic changes that drive inflammatory responses. However, the role of macrophage metabolic reprogramming in bacterial adaptation to the intracellular environment has not been explored. Here, using metabolic profiling and dual RNA sequencing, we show that succinate accumulation in macrophages is sensed by intracellular Salmonella Typhimurium (S. Tm) to promote antimicrobial resistance and type III secretion. S. Tm lacking the succinate uptake transporter DcuB displays impaired survival in macrophages and in mice. Thus, S. Tm co-opts the metabolic reprogramming of infected macrophages as a signal that induces its own virulence and survival, providing an additional perspective on metabolic host–pathogen cross-talk. [ABSTRACT FROM AUTHOR]

Background: The global production of glycerol is increasing year by year since the demands of biodiesel is rising. It is benefit for high-yield succinate synthesis due to its high reducing property. A. succinogenes, a succinate-producing candidate, cannot grow on glycerol anaerobically, as it needs a terminal electron acceptor to maintain the balance of intracellular NADH and NAD+. Microbial fuel cell (MFC) has been widely used to release extra intracellular electrons. However, A. succinogenes is a non-electroactive strain which need the support of electron shuttle in MFC, and pervious research showed that acid-tolerant A. succinogenes has higher content of unsaturated fatty acids, which may be beneficial for the transmembrane transport of lipophilic electron shuttle. Results: MFC-assisted succinate production was evaluated using neutral red as an electron shuttle to recover the glycerol utilization. First, an acid-tolerant mutant JF1315 was selected by atmospheric and room temperature plasma (ARTP) mutagenesis aiming to improve transmembrane transport of neutral red (NR). Additionally, MFC was established to increase the ratio of oxidized NR to reduced NR. By combining these two strategies, ability of JF1315 for glycerol utilization was significantly enhanced, and 23.92 g/L succinate was accumulated with a yield of 0.88 g/g from around 30 g/L initial glycerol, along with an output voltage above 300 mV. Conclusions: A novel MFC-assisted system was established to improve glycerol utilization by A. succinogenes for succinate and electricity production, making this system as a platform for chemicals production and electrical supply simultaneously. [ABSTRACT FROM AUTHOR]

In this study, curcumin nanosuspensions (Cur-NSs) were prepared using D-alpha-tocopheryl polyethylene glycol succinate (vitamin E TPGS), and their physical properties (i.e., particle size, dispersion stability) were investigated. Also, the antioxidant activity of Cur-NSs in emulsion systems was evaluated by peroxide value change and the oxidation products were monitored by nuclear magnetic resonance spectroscopy. The initial particle size of Cur-NSs containing a high curcumin concentration (0.30–0.50%) was smaller than that at low concentration (0.05–0.15%). When Cur-NSs were stored at 25°C, aggregation of curcumin particles was observed with increasing storage period. The aggregation rate decreased as the curcumin concentration in Cur-NSs increased. These observations were supported by changes in the transmission intensity profile using Turbiscan. Regarding the antioxidant activity of Cur-NSs, the emulsions with curcumin additions of 200 mg/kg or higher showed improved antioxidant effects compared to the control, but a lower activity than the positive control with 200 mg/kg catechin. [ABSTRACT FROM AUTHOR]

Ficin was immobilized by entrapment into gels based on food-grade chitosan and chitosan succinate. The optimum ratio of protein content (mg/g of carrier), total activity (in U/mL of solution), and specific activity (in U/mg of protein) was achieved when ficin was immobilized by entrapment into the gels (based on food-grade chitosan and chitosan succinate) using glycine buffer at pH 9.0 and 9.5, respectively. The proposed technology is accessible for Russian laboratories and is promising for further investigation of the immobilized ficin preparations in medicine and the pharmaceutical industry because of the combination of relatively inexpensive components. [ABSTRACT FROM AUTHOR]

Succinate dehydrogenase (SDH) is an inner mitochondrial membrane protein complex that links the Krebs cycle to the electron transport system. It can produce significant amounts of superoxide (O 2) and hydrogen peroxide (H2O2); however, the precise mechanisms are unknown. This fact hinders the development of next-generation antioxidant therapies targeting mitochondria. To help address this problem, we developed a computational model to analyze and identify the kinetic mechanism of O 2 and H2O2 production by SDH. Our model includes the major redox centers in the complex, namely FAD, three iron-sulfur clusters, and a transiently bound semiquinone. Oxidation state transitions involve a one- or two-electron redox reaction, each being thermodynamically constrained. Model parameters were simultaneously fit to many data sets using a variety of succinate oxidation and free radical production data. In the absence of respiratory chain inhibitors, model analysis revealed the 3Fe-4S iron-sulfur cluster as the primaryO 2 source. However, when the quinone reductase site is inhibited or the quinone pool is highly reduced, O 2 is generated primarily by the FAD. In addition, H2O2 production is only significant when the enzyme is fully reduced, and fumarate is absent. Our simulations also reveal that the redox state of the quinone pool is the primary determinant of free radical production by SDH. In this study, we showed the importance of analyzing enzyme kinetics and associated side reactions in a consistent, quantitative, and biophysically detailed manner using a diverse set of experimental data to interpret and explain experimental observations froma unified perspective. [ABSTRACT FROM AUTHOR]

Propionyl-CoA carboxylase (PCC) is a promising enzyme in the fields of biological CO 2 utilization, synthesis of natrual products, and so on. The activity and substrate specificity of PCC are dependent on its key subunit carboxyltransferase (CT). To obtain PCC with high enzyme activity, seven pccB genes encoding CT subunit from diverse microorganisms were expressed in recombinant E. coli , and PccB from Bacillus subtilis showed the highest activity in vitro. To further optimize this protein using directed evolution, a genetic screening system based on oxaloacetate availability was designed to enrich the active variants of PccB Bs. Four amino acid substitutions (D46G, L97Q, N220I and I391T) proved of great assistance in PccB Bs activity improvement, and a double mutant of PccB Bs (N220I/I391T) showed a 94-fold increase of overall catalytic efficiency indicated by k cat / K m. Moreover, this PccB Bs double mutant was applied in construction of new succinate biosynthetic pathway. This new pathway produces succinate from acetyl-CoA with fixation of two CO 2 molecules, which was confirmed by isotope labeling experiment with NaH13CO 3. Compared with previous succinate production based on carboxylation of phosphoenolpyruvate or pyruvate, this new pathway showed some advantages including higher CO 2 fixation potentiality and availability under aerobic conditions. In summary, this study developed a PCC with high enzyme activity which can be widely used in biotechnology field, and also demonstrated the feasibility of new succinate biosynthetic pathway with two CO 2 fixation reactions. • Several propionyl-CoA carboxylases (PCCs) were cloned and assayed in vitro. • Activity of B. subtilis PCC were notable improved by directed evolution. • The improved PCC was applied in a novel succinate biosynthetic pathway. • Succinate is produced from acetyl-CoA with fixation of two CO 2 molecules. [ABSTRACT FROM AUTHOR]

Insight into the impact of mixed internal donors, comprising bis-methoxymethyl-fluorene (BMF) and 2,2-diisopropyl succinate (DIS), on the crystalline structure of MgCl2 supported Ziegler–Natta catalysts is developed. The propylene polymerization performance of the catalysts is studied and compared with related single internal electron donor systems. A study of the crystalline structure of the catalysts reveals that an increase in the DIS content leads to a relatively higher amount of the α-form over the β-form in the catalyst matrix. The catalyst performance is explained through the coordination nature and composition of the internal donors. Molecular weight analysis shows that the molecular weight distribution of these systems is within the range 2.8–3.3. Meanwhile, in these systems an increase in the DIS content is conducive to improving not only the relative content but also the lamellar thickness of the polymer chains. A promising feature of the obtained results is that they provide guidelines for synthesizing desired polymer properties through a change in the mixture of internal donors in the catalysts. [ABSTRACT FROM AUTHOR]

DNA methylation is one of the best studied epigenetic modifications. Alteration of the global DNA methylation level occurs in abnormal cells, such as those associated with cancers and Alzheimer's disease. Several assays are used to determine the global DNA methylation level, including the bisulfite-based assay, high-performance liquid chromatography (HPLC)–based assay, enzyme-linked immunosorbent assay (ELISA), and methyl acceptance assay. However, these assays require several cumbersome steps to detect methylation levels. We developed a simpler enzymatic assay for the quantification of the global DNA methylation level using the Ten-eleven translocation (TET) protein. TET proteins mediate DNA demethylation through the oxidation of 5-methylcytosine (5mC) in CpG in mammalian cells. Succinate is produced during this oxidation reaction, and the amount of succinate produced correlates to the global DNA methylation level. The catalytic domain of the TET2 was expressed in Escherichia coli (E. coli), and the purified TET2 catalytic domain was reacted with human genomic DNA. The reaction solution was used for enzymatic succinate quantification with no purification step. The results showed that the succinate produced through TET-mediated oxidation increased with increasing global DNA methylation levels in human genomic DNA, which was determined using the bisulfite method. These results show that the global DNA methylation level is quantifiable by measuring the amount of succinate produced by the TET2-mediated 5mC oxidation reaction. [ABSTRACT FROM AUTHOR]

Despite advances in therapy, myocardial infarction (MI) remains a leading cause of death worldwide. Recently, the mitochondrion has been targeted in cardio-protection due to its role in reperfusion injury after MI. Similarly, the mitochondrion has been reported to play critical role in cardiovascular disease-associated liver dysfunctions. Medicinal plants are used in the treatment of cardiovascular diseases in Nigeria Ethnomedicine, particularly Bridelia ferruginea (BF). The study explored the effect of aqueous leaves extract of BF (AEBF) as heart and liver mitochondrial permeability transition (mPT) pore opening inhibitor using Isoprenaline-hydrochloride (ISO)-induced MI rat model. Twenty rats were used in the study, while eight were orally and daily pretreated for 14 days with 200 or 400 mg/kg of AEBF before intraperitoneal injection of ISO (100 mg/kg) for 2 days at 24 h interval. The mPT pore opening was spectrophotometrically assessed under sodium succinate energized condition at 540 nm. Results: The AEBF at 200 and 400 mg/kg decreased elevated plasmatic creatine kinase, lactate dehydrogenase and aspartate aminotransferase in ISO-induced MI in rats. Similarly, increased heart and liver lipid peroxides were inhibited by AEBF. The mPT pore opening of ISO-induced MI in rat heart was inhibited by AEBF and this impacted positively on the liver mPT pore. Furthermore, histologic examinations showed that 400 mg/kg AEBF pretreatment showed absence of lesions and necrotic cells. Conclusion: Taken together AEBF protected the heart and liver of ISO-induced MI in rats via inhibition of mPT pore opening. Hence, this may be relevant in cardio- and hepato-protection. [ABSTRACT FROM AUTHOR]

Glimepiride (GMD) is a hypoglycemic agent that has variation in bioavailability for its unexpected absorption. Glimepiride was formulated in a buccal film loaded with a nanobased formulation to enhance its absorption via buccal mucosa. Nanostructured lipid carriers (NLCs) and D-α-tocopherol polyethylene glycol 1000 succinate-based micelles enhance GMD solubility and improve its permeation through the buccal mucosa. The formulation variables were optimized using a Box-Behnken design. These factors, such as the percent of micelles relative to NLC (X1), the percent of Carbopol (X2), and the percent of permeation enhancer (X3), were investigated for their effect on the initial release (Y1) and the cumulative release after 6 hours (Y2). The optimum levels for X1, X2, and X3 were 100%, 0.05%, and 1.8%, respectively. The optimized formulation revealed that the permeation of GMD from the film was in favor of micelles. This optimized film was then coated with ethyl cellulose to direct the release only through the buccal mucosa. The optimized unidirectional GMD transmucosal film showed a release of 93.9% of GMD content at 6 hours compared to 60.41% of GMDrelease from the raw GMD film. This finding confirmed the suitability of transmucosal delivery ofGMDvia the buccal mucosa. [ABSTRACT FROM AUTHOR]

Blends of poly(lactic acid) (PLA) with poly(butylene succinate) (PBS) were compounded in the presence of dicumyl peroxide (DCP) to improve the compatibility and foaming capabilities. PLA/PBS blends with a weight ratio of 40/60 and DCP contents of 0, 0.1, 0.4 and 1 wt% were analyzed. Blends and neat materials were foam injection molded using azodicarbonamide as a chemical foaming agent. The thermal and rheological behaviors of materials are discussed. The morphologies and mechanical responses of the foamed samples are compared and analyzed. The best blend results were obtained with 0.1 wt% of peroxide, reaching impact strength values similar to those of neat-foamed PBS and cell population densities higher than neat PLA. Peroxide contents higher than 0.4 wt% tend to decrease the performance of the blend due to excessive crosslinking. [ABSTRACT FROM AUTHOR]

To assess the role of core metabolism genes in bacterial virulence - independently of their effect on growth - we correlated the genome, the transcriptome and the pathogenicity in flies and mice of 30 fully sequenced Pseudomonas strains. Gene presence correlates robustly with pathogenicity differences among all Pseudomonas species, but not among the P. aeruginosa strains. However, gene expression differences are evident between highly and lowly pathogenic P. aeruginosa strains in multiple virulence factors and a few metabolism genes. Moreover, 16.5%, a noticeable fraction of the core metabolism genes of P. aeruginosa strain PA14 (compared to 8.5% of the non-metabolic genes tested), appear necessary for full virulence when mutated. Most of these virulence-defective core metabolism mutants are compromised in at least one key virulence mechanism independently of auxotrophy. A pathway level analysis of PA14 core metabolism, uncovers beta-oxidation and the biosynthesis of amino-acids, succinate, citramalate, and chorismate to be important for full virulence. Strikingly, the relative expression among P. aeruginosa strains of genes belonging in these metabolic pathways is indicative of their pathogenicity. Thus, P. aeruginosa strain-to-strain virulence variation, remains largely obscure at the genome level, but can be dissected at the pathway level via functional transcriptomics of core metabolism. [ABSTRACT FROM AUTHOR]

Acetate is the main by-product from microbial succinate production. In this study, we performed acetate removal by Methanosarcina barkeri 227 for succinate fermentation by Actinobacillus succinogenes 130Z. The acetoclastic methanogen M. barkeri requires similar environmental factors to A. succinogenes, and the conditions required for co-cultivation were optimized in this study: gas used for anaerobicization, strain adaptation, medium composition, pH adjustment, and inoculation time points. M. barkeri 227 was adapted to acetate for 150 days, which accelerated the acetate consumption to 9-fold (from 190 to 1726 mmol gDW−1 day−1). In the acetate-adapted strain, there was a noticeable increase in transcription of genes required for acetoclastic pathway—satP (acetate transporter), ackA (acetate kinase), cdhA (carbon monoxide dehydrogenase/acetyl-CoA synthase complex), and mtrH (methyl-H4STP:CoM methyltransferase), which was not induced before the adaptation process. The activities of two energy-consuming steps in the pathway—acetate uptake and acetate kinase—increased about 3-fold. This acetate-adapted M. barkeri could be successfully applied to succinate fermentation culture of A. succinogenes, but only after pH adjustment following completion of fermentation. This study suggests the utility of M. barkeri as an acetate scavenger during fermentation for further steps towards genetic and process engineering. [ABSTRACT FROM AUTHOR]

Tandem bis‐alkoxycarbonylation of alkynes allows for the preparation of 2‐substituted succinates from alkynes and nucleophile alcohol via two successive alkoxycarbonylation with advantages of 100 % atomic economy and simplified one‐pot operation. Herein, the one‐pot tandem bis‐alkoxycarbonylation of alkynes was accomplished over the bi‐functional catalytic system containing Xantphos‐modified Pd‐complex and Lewis super‐acid of Al(OTf)3. It was found that, via the synergetic catalysis, the involved Xantphos‐modified Pd‐complex was responsible for the activation of CO and the alkynes through coordination to Pd‐center while Al(OTf)3 was in charge of the activation of the alcohol to facilitate the formation of [Pd−H]+ active species. The in situ high‐pressure FT‐IR analysis, coupled with 1H/13C NMR spectral characterizations, confirmed that the introduced Al(OTf)3 with intensive oxophilicity (via acid‐base pair interaction) was able to activate nucleophilic MeOH to be a reliable proton‐donor (i. e. hydride‐source) to warrant the formation and stability of [Pd−H]+ species upon the oxidation of Pd0 by H+ (Pd0+H+→[PdII−H]+). Over the developed bi‐functional catalytic system, the yields of the target diesters were obtained in the range of 36∼86 % in this sequence with the wide substrate scope. [ABSTRACT FROM AUTHOR]

The study of cancer metabolism has evolved vastly beyond the remit of tumour proliferation and survival with the identification of the role of 'oncometabolites' in tumorigenesis. Simply defined, oncometabolites are conventional metabolites that, when aberrantly accumulated, have pro-oncogenic functions. Their discovery has led researchers to revisit the Warburg hypothesis, first postulated in the 1950s, of aberrant metabolism as an aetiological determinant of cancer. As such, the identification of oncometabolites and their utilization in diagnostics and prognostics, as novel therapeutic targets and as biomarkers of disease, are areas of considerable interest in oncology. To date, fumarate, succinate, L-2-hydroxyglutarate (L-2-HG) and D-2-hydroxyglutarate (D-2-HG) have been characterized as bona fide oncometabolites. Extensive metabolic reprogramming occurs during tumour initiation and progression in renal cell carcinoma (RCC) and three oncometabolites - fumarate, succinate and L-2-HG - have been implicated in this disease process. All of these oncometabolites inhibit a superfamily of enzymes known as α-ketoglutarate-dependent dioxygenases, leading to epigenetic dysregulation and induction of pseudohypoxic phenotypes, and also have specific pro-oncogenic capabilities. Oncometabolites could potentially be exploited for the development of novel targeted therapies and as biomarkers of disease. [ABSTRACT FROM AUTHOR]

The use of a modified, four-stage purification scheme allowed us to obtain electrophoretically homogeneous preparations of constitutive forms of succinate dehydrogenase from maize (Zea mays L.) scutellum in the late stages of seed germination. It has been established that the isoenzymes differed significantly in their quaternary structure. Thus, succinate dehydrogenase 1 turned out to be a heterotetramer, and succinate dehydrogenase 2 turned out to be a heteroterodimer. It was found that their main catalytic and kinetic characteristics also differed, in particular, by their affinity to the substrate (succinate) and the value of pH optimum of the catalyzed reaction. Succinate dehydrogenase 2 was characterized by enhanced resistance to a specific inhibitor—malonate. [ABSTRACT FROM AUTHOR]

Since the identification of succinate's receptor in 2004, studies supporting the involvement of succinate signaling through its receptor in various diseases have accumulated and most of these investigations have highlighted succinate's pro-inflammatory role. Taken with the fact that succinate is an intermediate metabolite in the center of mitochondrial activity, and considering its potential regulation of protein succinylation through succinyl-coenzyme A, a review on the overall multifaceted actions of succinate to discuss whether and how these actions relate to the cellular locations of succinate is much warranted. Mechanistically, it is important to consider the sources of succinate, which include somatic cellular released succinate and those produced by the microbiome, especially the gut microbiota, which is an equivalent, if not greater contributor of succinate levels in the body. Continue learning the critical roles of succinate signaling, known and unknown, in many pathophysiological conditions is important. Furthermore, studies to delineate the regulation of succinate levels and to determine how succinate elicits various types of signaling in a temporal and spatial manner are also required. [ABSTRACT FROM AUTHOR]

The first example of the bis‐alkoxycarbonylation of acrylic esters and acrylic amides, leading to differently substituted 1,1,2‐ethanetricarboxylate compounds and 2‐carbamoylsuccinates respectively, is reported. The catalyst is formed in situ by mixing Pd(TFA)2 (TFA=trifluoroacetate) and the ligand bis(2,6‐dimethylphenyl)butane‐2,3‐diimine. The reaction, that proceeds using p‐benzoquinone as oxidant and p‐toluenesulfonic acid as additive, has been applied to variously substituted electron‐poor alkenes, employing different alcohols as nucleophiles, under very mild reaction conditions (4 bar of carbon monoxide at 20 °C). Remarkably, this catalytic system is able to promote the carbonylation of both the β‐ and the generally unreactive α‐positions of acrylic esters and amides, allowing the formation of bis‐alkoxycarbonylated products in good to excellent yields (up to 98%). The trend of reactivity, observed with the different electron‐deficient olefins, has been rationalized on the basis of the proposed catalytic cycle and DFT calculations. [ABSTRACT FROM AUTHOR]

In the present study, a methanogenic alkane-degrading (a mixture of C9 to C12n-alkanes) culture enriched from production water of a low-temperature oil reservoir was established and assessed. Significant methane production was detected in the alkane-amended enrichment cultures compared with alkane-free controls over an incubation period of 1 year. At the end of the incubation, fumarate addition metabolites (C9 to C12 alkylsuccinates) and assA genes (encoding the alpha subunit of alkylsuccinate synthase) were detected only in the alkane-amended enrichment cultures. Microbial community analysis showed that putative syntrophic n-alkane degraders (Smithella) capable of initiating n-alkanes by fumarate addition mechanism were enriched in the alkane-amended enrichment cultures. In addition, both hydrogenotrophic (Methanocalculus) and acetoclastic (Methanothrix) methanogens were also observed. Our results provide further evidence that alkanes can be activated by addition to fumarate under methanogenic conditions. [ABSTRACT FROM AUTHOR]

In this study, it focused on empty fruit brunch (EFB) fibres reinforcement in polybutylene succinate (PBS) with modified tapioca starch by using hot press technique for the use of agricultural mulch film. Mechanical, morphological and thermal properties were studied. Mechanical analysis showed decreased in values of modulus strength for both tensile and flexural testing for fibres insertion. Higher EFB fibre contents in films resulted lower mechanical properties due to poor fibre wetting from insufficient matrix. This has also found evident in SEM micrograph, showing poor interfacial bonding. Water vapour permeability (WVP) shows as higher hydrophilic EFB fibre reinforcement contents, the rate of WVP also increase. Besides this, little or no significant changes on thermal properties for composite films. This is because high thermal stability PBS polymer show its superior thermal properties dominantly. Even though EFB fibres insertion into PBS/tapioca starch biocomposite films have found lower mechanical properties. It successfully reduced the cost of mulch film production without significant changes of thermal performances. [ABSTRACT FROM AUTHOR]

In situ generated palladium on aluminum oxide provides an active and efficient catalytic system for the preparation of arylmethylidene succinates using the Heck–Matsuda reaction. Beside the monoarylation the first examples of the biarylation of these monomers will be described. [ABSTRACT FROM AUTHOR]

Fusarubin analogues of Fusarium oxysporum f. sp. ciceris were investigated for antifungal activity in vitro against five soil borne phytopathogenic fungi. 3-O-Methyl-8-O-methyl-fusarubin was inhibitory towards S. sclerotiorum (EC50 0.33 mmol L−1) and Sclerotium rolfsii (EC50 0.38 mmol L−1). A structure–antifungal activity relationship of fusarubin analogues was established from their activity performance. Possible mechanism of action of these compounds was studied using molecular docking and simulations against three target enzymes which revealed receptor ligand binding affinity. Docking of 3-O-methyl-8-O-methyl-fusarubin into the succinate dehydrogenase site revealed formation of salt bridge, hydrogen bond, π–anion, π–alkyl, and Van der Waals interactions. [ABSTRACT FROM AUTHOR]