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Sepsis is a life-threatening condition, and treatment for sepsis in clinic is often not available, partially due to insufficient understanding of the pathogenesis of sepsis. Extensive study to elucidate the pathogenesis is required to improve the clinical management and outcome of sepsis. In this study, we investigated the pathogenesis of sepsis using peripheral blood mononuclear cells (PBMCs) from septic patients and studied the underlying mechanism of miR-16-5p on aerobic glycolysis in lipopolysaccharide (LPS)-treated THP1 and Raw264.7 cells. The levels of RNA and protein were determined by real-time quantitative PCR and immunoblotting assay, respectively. The production of high mobility group box 1 (HMGB1) was measured by enzyme-linked immunosorbent assay. The levels of succinate and lactate were determined using colorimetric kits. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were measured by extracellular flux analyzer. The results showed that the expression of miR-16-5p was elevated, while sirtuin 3 (SIRT3) was decreased in PBMCs from septic patients and LPS-treated cells, along with accumulation of acetylated succinate dehydrogenase complex, subunit A. Concomitantly, an increase in HMGB1, succinate, lactate, as well as ECAR and a decrease in OCR were observed. Knockdown of miR-16-5p upregulated SIRT3 expression, facilitated SDHA deacetylation, and attenuated sepsis-related aerobic glycolysis. Further study identified that SIRT3 is targeted by miR-16-5p, and overexpression of SIRT3 rescued LPS-induced responses via deacetylation of SDHA. Our findings revealed a novel miR-16-5p-regulated SIRT3-SDHA axis in sepsis and provided novel insights for sepsis treatment.

The current method used in latex industries to determine the volatile fatty acids contents of Hevea brasiliensis latex is steam distillation. However, the accuracy of the method has been debated for some time. We assessed the accuracy of the method and developed a new, more reliable high-performance liquid chromatographic method of determining acids in latex. The volatile fatty acids (formic, acetic, propionic, butyric, and valeric acids) and nonvolatile organic acids (oxalic, malic, lactic, citric, and succinic acids) in latex are directly determined simultaneously for the first time with high sensitivity and without losses during sample preparation. To avoid errors from derivatization, an acid-resistant Prevail HPLC column and a gradient mobile phase of 25 mM potassium dihydrogen phosphate (pH 2.5) and acetonitrile were employed. Under optimum conditions, the calibrations of both types of acids demonstrated satisfactory correlation coefficients of ≥0.990, with limits of detection ranging from 0.02 to 395 mM. The developed method demonstrated the profiles of acids in field and concentrated latex of the same batch. Moreover, the evolution of the profiles of all studied acids in both types of latex during a 3-month period was also revealed.

Deregulated metabolism is a well-known feature of several challenging diseases, including diabetes, obesity and cancer. Besides their important role as intracellular bioenergetic molecules, dietary nutrients and metabolic intermediates are released in the extracellular environment. As such, they may achieve unconventional roles as hormone-like molecules by activating cell surface G-protein-coupled receptors (GPCRs) that regulate several pathophysiological processes. In this review, we provide an insight into the role of lactate, succinate, fatty acids, amino acids as well as ketogenesis-derived and β-oxidation-derived intermediates as extracellular signalling molecules. Moreover, the mechanisms by which their cognate metabolite-sensing GPCRs integrate nutritional and metabolic signals with specific intracellular pathways will be described. A better comprehension of these aspects is of fundamental importance to identify GPCRs as novel druggable targets.

The high viscosity and low solubility of octenyl succinate starch (OSAS) in water often lead to low reaction efficiency and uneven distribution of OSA groups, which can be solved by subjecting OSA starch to enzymatic digestion. Waxy corn starch is used to produce OSAS. The molecular weight of enzymolysis modified octenyl succinate starches (E-OSAS) decreased with the addition of enzyme, and the substitution of enzymatically digested OSAS was larger than that of OSAS. As the addition of pullulanase increased, the substitution of E-OSAS tended to increase and the apparent viscosity decreased significantly. The smaller its particle size and polydispersity index (PDI), the larger the absolute value of the zeta potential. E

Background: SUCNR1 is a sensor of extracellular succinate, a Krebs cycle intermediate generated in excess during oxidative stress and has been linked to metabolic regulation and inflammation. While mast cells express SUCNR1, its role in mast cell reactivity and allergic conditions such as asthma remains to be elucidated. Methods: Cord blood-derived mast cells and human mast cell line LAD-2 challenged by SUCNR1 ligands were analyzed for the activation and mediator release. Effects on mast cell-dependent bronchoconstriction were assessed in guinea pig trachea and isolated human small bronchi challenged with antigen and anti-IgE, respectively. Results: SUCNR1 is abundantly expressed on human mast cells. Challenge with succinate, or the synthetic non-metabolite agonist cis-epoxysuccinate, renders mast cells hypersensitive to IgE-dependent activation, resulting in augmented degranulation and histamine release, de novo biosynthesis of eicosanoids and cytokine secretion. The succinate-potentiated mast cell reactivity was attenuated by SUCNR1 knockdown and selective SUCNR1 antagonists and could be tuned by pharmacologically targeting protein kinase C and extracellular signal-regulated kinase. Both succinate and cis-epoxysuccinate dose-dependently potentiated antigen-induced contraction in a mast cell-dependent guinea pig airway model, associated with increased generation of cysteinyl-leukotrienes and histamine in trachea. Similarly, cis-epoxysuccinate aggravated IgE-receptor-induced contraction of human bronchi, which was blocked by SUCNR1 antagonism. Conclusion: SUCNR1 amplifies IgE-receptor-induced mast cell activation and allergic bronchoconstriction, suggesting a role for this pathway in aggravation of allergic asthma, thus linking metabolic perturbations to mast cell-dependent inflammation.

Small molecule drug intervention for chondrocytes is a valuable method for the treatment of osteoarthritis (OA). The 4-octyl itaconate (OI) is a cellular derivative of itaconate with sound cell permeability and transformation rate. We attempted to confirm the protective role of OI in chondrocytes and its regulatory mechanism. We used lipopolysaccharide (LPS) to induce chondrocyte inflammation injury. After the OI treatment, the secretion and mRNA expression of Il-6, Il-10, Mcp-1 and Tnf-α were detected by ELISA and qPCR. The protective effect of OI on articular cartilage was further verified in surgical destabilization of the medial meniscus model of OA. Cell death and apoptosis were evaluated based on CCK8, LDH, Typan blue staining, Annexin V and TUNEL analyses. The small interfering RNAs were used to knockout the Nrf2 gene of chondrocytes to verify the OI-mediated Nrf2 signalling pathway. The results revealed that OI protects cells from LPS-induced inflammatory injury and attenuates cell death and apoptosis induced by LPS. Similar protective effects were also observed on articular cartilage in mice. The OI activated Nrf2 signalling pathway and promoted the stable expression and translocation of Nrf2 into the nucleus. When the Nrf2 signalling pathway was blocked, the protective effect of OI was significantly counteracted in chondrocytes and a mouse arthritis model. Both itaconate and its derivative (i.e., OI) showed important medical effects in the treatment of OA.

Anaerobic toluene degradation proceeds by fumarate addition to produce (R)-benzylsuccinate as first intermediate, which is further degraded via β-oxidation by five enzymes encoded in the conserved bbs operon. This study characterizes two enzymes of this pathway, (E)-benzylidenesuccinyl-CoA hydratase (BbsH), and (S,R)-2-(α-hydroxybenzyl)succinyl-CoA dehydrogenase (BbsCD) from Thauera aromatica. BbsH, a member of the enoyl-CoA hydratase family, converts (E)-benzylidenesuccinyl-CoA to 2-(α-hydroxybenzyl)succinyl-CoA and was subsequently used in a coupled enzyme assay with BbsCD, which belongs to the short-chain dehydrogenases/reductase (SDR) family. The BbsCD crystal structure shows a C2-symmetric heterotetramer consisting of BbsC2 and BbsD2 dimers. BbsD subunits are catalytically active and capable of binding NAD+ and substrate, whereas BbsC subunits represent built-in pseudoenzyme moieties lacking all motifs of the SDR family required for substrate binding or catalysis. Molecular modeling studies predict that the active site of BbsD is specific for conversion of the (S,R)-diastereomer of 2-(α-hydroxybenzyl)succinyl-CoA to (S)-2-benzoylsuccinyl-CoA by hydride transfer to the re-face of nicotinamide adenine dinucleotide (NAD)+ . Furthermore, BbsC subunits are not engaged in substrate binding and merely serve as scaffold for the BbsD dimer. BbsCD represents a novel clade of related enzymes within the SDR family, which adopt a heterotetrameric architecture and catalyze the β-oxidation of aromatic succinate adducts.

Enhancing the specific surface area of stationary phase is important in chromatographic science, especially in open-tubular column in which the coating only exists on the inner surface. In this work, a porous layer open-tubular (PLOT) column with stationary phase of styrene and itaconic acid-copolymerized polymer was developed. Thermal-initiated polymerization method with strategies like controlling the ratio of reaction reagents to solvents and reaction time, confinement by the narrow inner diameter of capillary were used for preparing the stationary phase with uniform structure and relatively thick layer. Due to the high separation efficiency and capacity, the PLOT column was used for capillary electrochromatography (CEC) separation of multiple groups of analytes like alkylbenzenes, phenyl amines, phenols, vanillins, and sulfonamides with theoretical plates (N) up to 1,54,845 N/m. In addition, due to high permeability of the CEC column and large electroosmotic flow mobility generated by abundant carboxyl groups in the coating material, the PLOT-CEC column was successfully coupled with mass spectrometry (MS) through a sheath flow interface. The developed PLOT-CEC-MS method was used for the analysis of antiseptics like parabens and herbicides like pyridines.

The tricarboxylic acid (TCA) cycle is the epicenter of cellular aerobic metabolism. TCA cycle intermediates facilitate energy production and provide anabolic precursors, but also function as intra- and extracellular metabolic signals regulating pleiotropic biological processes. Despite the importance of circulating TCA cycle metabolites as signaling molecules, the source of circulating TCA cycle intermediates remains uncertain. We observe that in mice, the concentration of TCA cycle intermediates in the portal blood exceeds that in tail blood indicating that the gut is a major contributor to circulating TCA cycle metabolites. With a focus on succinate as a representative of a TCA cycle intermediate with signaling activities and using a combination of gut microbiota depletion mouse models and isotopomer tracing, we demonstrate that intestinal microbiota is not a major contributor to circulating succinate. Moreover, we demonstrate that endogenous succinate production is markedly higher than intestinal succinate absorption in normal physiological conditions. Altogether, these results indicate that endogenous succinate production within the intestinal tissue is a major physiological source of circulating succinate. These results provide a foundation for an investigation into the role of the intestine in regulating circulating TCA cycle metabolites and their potential signaling effects on health and disease.

A new amide (1), two new phenylpropanoid derivatives (2, 3), along with three new natural products, including three nitrogen chirality compounds, N-(3-methoxy-1,3-dioxopropyl)-D-phenylalanine methyl ester (4), N-(3-methoxy-1,3-dioxopropyl)-L-phenylalanine methyl ester (5), and N-acetyl-L-phenylalanine methyl ester (6), as well as dimethyl (2R,3R)-2-hydroxy-3-(((E)-3-(4-hydroxyphenyl)acryloyl)oxy)succinate (7) and dimethyl (S,E)-2-((3-(4-hydroxy-3-methoxyphenyl)acryloyl)oxy)succinate (8) were isolated from Delphinium kamaonense Hunth. Their structures were elucidated by extensive analysis of 1D and 2D NMR, and HR-ESI-MS experiments, and the absolute configurations were determined by comparative analysis of specific optical rotation. Compound 1 exhibited a moderate cytotoxicity effect against Hep-3B cancer cell lines (IC

A Pd-catalyzed asymmetric double hydroxycarbonylation of terminal alkynes was developed by using relay catalysis, providing a highly efficient route to chiral succinic acids (41 examples, 76-94 %, 94-99 % ee). Key to success was the combinatorial use of a Pd precursor with two distinct phosphine ligands in one pot. The synthetic utilities of this protocol were showcased in the facile synthesis of key intermediates for chiral pharmaceuticals.

Summary The unconventional yeast Pichia kudriavzevii is renowned for its ability to survive at low pH and has been exploited for the industrial production of various organic acids, especially succinic acid (SA). However, P. kudriavzevii can also utilize the di‐ and tricarboxylate intermediates of the Krebs cycle as the sole carbon sources for cell growth, which may adversely affect the extracellular accumulation of SA. Because the carboxylic acid transport machinery of P. kudriavzevii remains poorly understood, here, we focused on studying its SA transportation process from the perspective of mining and characterization of dicarboxylate transporters in a newly isolated acid‐tolerant P. kudriavzevii strain CY902. Through genome sequencing and transcriptome analysis, two JEN family carboxylate transporters (PkJEN2‐1 and PkJEN2‐2) were found to be involved in SA transport. Substrate specificity analysis revealed that both PkJEN proteins are active dicarboxylate transporters, that can effectively import succinate, fumarate and L‐malate into the cell. In addition, PkJEN2‐1 can transport α‐ketoglutarate, while PkJEN2‐2 cannot. Since PkJEN2‐1 shows higher transcript abundance than PkJEN2‐2, its role in dicarboxylate transport is more important than PkJEN2‐2. In addition, PKJEN2‐2 is also responsible for the uptake of citrate. To our best knowledge, this is the first study to show that a JEN2 subfamily transporter is involved in tricarboxylate transport in yeast. A combination of model‐based structure analysis and rational mutagenesis further proved that amino acid residues 392‐403 of the tenth transmembrane span (TMS‐X) of PkJEN2‐2 play an important role in determining the specificity of the tricarboxylate substrate. Moreover, these two PkJEN transporters only exhibited inward transport activity for SA, and simultaneous inactivation of both PkJEN transporters reduced the SA influx, resulting in enhanced extracellular accumulation of SA in the late stage of fermentation. This work provides useful information on the mechanism of di‐/tricarboxylic acid utilization in P. kudriavzevii, which will help improve the organic acid production performance of this microbial chassis., Two JEN2 transporters responsible for the utilization of dicarboxylic acids in P. kudriavzevii were identified and functionally characterized. The PkJEN2‐2 transporter also possesses specific tricarboxylic acid transportation activity. Inactivation of PkJEN transporters can be used as a useful strategy to increase SA titer in P. kudriavzevii.

1,2,3-Trisubstituted donor-acceptor cyclopropenes (DACPs) generated in situ from enoldiazo compounds react with nucleophiles to form α-substituted succinic acid derivatives in high yields. Initial dirhodium(II) carboxylate catalysis rapidly converts enoldiazo-acetates or -acetamides to DACPs that undergo catalyst-free Favorskii ring opening with amines, and also with anilines, alcohols, and thiols, when facilitated by catalytic amounts of 4-dimethylaminopyridine (DMAP). This methodology provides easy access to mixed esters and amides of monosubstituted succinic acids, including derivatives of naturally occurring compounds. It also affords dihydrazide, dihydroxamic acid, and diamide derivatives, as well as α-substituted tetrahydropyridazine-3,6-diones in high yields. Attempts to generate optically enriched DACPs were not successful because their populations having the R and S configurations formed with a chiral dirhodium catalyst are quite similar, and the loss of enantiocontrol likely originates from the DACP ring forming step which is reversible with its intermediate metal carbene.

A pair of enantiomeric ligands, (2R,3R)-dibenzyl-2,3-bis(isonicotinoyloxy)succinate ((R,R)-L) and (2S,3S)-dibenzyl-2,3-bis(isonicotinoyloxy)succinate ((S,S)-L), are designed and synthesized. Seven copper (II) coordination polymers {[Cu((R,R)-L)Br

QF-036 is an HIV-1 maturation inhibitor in pre-clinical development, and its antiviral activity against a laboratory HIV-1 strain and two drug-resistant strains was determined in the C8166 line. QF-036 was also subjected to absorption, distribution and metabolism (ADM) assessment in vitro, and pharmacokinetic profiles were evaluated in rats and monkeys. The 50% effective concentrations (EC50 ) of QF-036 against the three strains were 20.36 nM, 0.39 μM and 2.11 nM, respectively, demonstrating better antiviral potential than the first-generation antiviral maturation inhibitor bevirimat. QF-036 demonstrated moderate cell permeability, high plasma protein binding ability and good metabolic stability in vitro. After oral QF-036 administration to rats and monkeys, both species exhibited moderate bioavailability, and the plasma drug exposure increased in an approximately dose-proportional manner. When administered orally (30 mg/kg) to monkeys, the QF-036 plasma concentration (Cmax ) peaked at 3671 ng/mL (4.82 μM), 12 to 2410 times higher than the EC50 of laboratory or resistant HIV-1 strains. Moreover, the plasma concentration of QF-036 at 12 hours after administration was 263 ng/mL (0.35 μM), which approximately matched the highest EC50 value of the three test strains. The favourable viral inhibitory activity and pharmacokinetic properties provide critical support for QF-036 as a promising anti-HIV therapeutic candidate.

In recent years, inhibitors of the BET bromodomain proteins, such as BRD4 inhibitors, have demonstrated robust antitumor activity. JQ-1, a representative small molecular BRD4 inhibitor, is also effective to block PD-1/PD-L1 signaling by significantly decreasing the PD-L1 expression on tumor cells. However, toxicity of BRD4 inhibitors on lymphoid and hematopoietic tissues limits their clinical usage. In this research, we designed and studied an immunogenic BRD4 inhibitor, SZU-119, by coupling JQ-1 with a TLR7 agonist, SZU-101. In vitro, SZU-119 stimulated the production of cytokines in mouse BMDCs and spleen lymphocytes, and inhibited the expression of PD-L1 in mouse B16 tumor cells. In vivo, SZU-119 suppressed the B16 tumor growth at both injected and uninjected sites, and prolonged the survival time of mice. SZU-119 elevated the number of total CD8+ and IFN-γ+ CD8+ T cells in spleens, with greater CTL cytotoxicity to B16 tumor cells. It was also observed that the infiltration of CD8+ T cells was increased in tumors at both local and distant sites, and the PD-L1 expression was decreased in tumor cells at the primary site. In conclusion, we have demonstrated that SZU-119 activated the innate immune cells, kept efficacy of PD-L1 blockade and abrogated immune toxicity, showing more potent antitumor effects than the simple mixture of SZU-101 and JQ-1 in a mouse melanoma model. Our work provides new insights for the development of anti-melanoma drugs that concurrently target innate and adaptive immunity.

Dimethyl itaconate (DI) is a membrane‐permeable itaconate derivative with anti‐inflammatory functions. However, the anti‐inflammatory effect of DI has never been studied in fungal keratitis. In this study, we tested the protective effect of DI against fungal keratitis and assessed the role of NF‐E2‐related factor‐2 (Nrf2)/heme oxygenase‐1 (HO‐1) signaling in this process. Eyes of C57BL/6 (B6) mice were treated with 2 mm DI after infection with Aspergillus fumigatus. Human corneal epithelial cells (HCECs) were pretreated with 0.25 mm DI and then incubated with A. fumigatus. Clinical scoring, slit‐lamp photography, myeloperoxidase determination, flow cytometry and immunostaining were used to assess the disease response and treatment efficacy. PCR, Western blot and ELISA were used to assess the expression of interleukin‐1β (IL‐1β), chemokine (C–X–C motif) ligand 1, IL‐6, IL‐8, Nrf2 and HO‐1. In addition, quantification of viable fungi, absorbance assays and fluorimetry were used to measure DI fungistatic activity. We observed that DI‐treated eyes showed decreased clinical scores, fungal loads, polymorphonuclear neutrophil (PMN) infiltration and cytokine expression, compared with phosphate‐buffered saline‐treated infected eyes. DI treatment decreased the cytokine levels in infected corneas and in HCECs stimulated with A. fumigatus. Moreover, DI treatment increased Nrf2 and HO‐1 expression in corneas and nuclear Nrf2 accumulation in HCECs. DI‐induced cytokine downregulation was inhibited by pretreatment with an Nrf2 or HO‐1 inhibitor. Finally, DI treatment reduced the A. fumigatus absorbance and fungal mass. These data indicate that DI protects against fungal keratitis by limiting inflammation via the Nrf2/HO‐1 signaling pathway and that DI inhibits the growth of A. fumigatus., In this study, we showed that dimethyl itaconate (DI) exerts protective effects in fungal keratitis. On the one hand, DI alleviates inflammation by activating the NF‐E2‐related factor‐2 (Nrf2)/heme oxygenase‐1 (HO‐1) signaling pathway in Aspergillus fumigatus‐induced keratitis. On the other hand, DI reduces the fungal load and inhibits the growth of A. fumigatus.

Large clinical trials and real-world studies have demonstrated that the beneficial effects of sodium-glucose co-transporter 2 (SGLT2) inhibitors on renal outcomes regardless of the presence of diabetes. However, the mechanism remains obscure. Here, we analyze the anti-fibrotic and anti-inflammatory effects of dapagliflozin, a SGLT2 inhibitor, on renal alternations using the ischemia/reperfusion-induced fibrosis model. Transcriptome and metabolome analysis showed that the accumulation of tricarboxylic acid (TCA) cycle metabolites and upregulation of inflammation in fibrosis renal cortical tissue were mitigated by dapagliflozin treatment. Moreover, dapagliflozin markedly relieved the activation of mammalian target of rapamycin and hypoxia inducible factor-1α signaling and restored tubular cell-preferred fatty acid oxidation. Notably, NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation was strikingly blocked by dapagliflozin. We further demonstrated that the immunomodulatory metabolite itaconate derived from the TCA cycle was significantly boosted as a result of decreased isocitrate dehydrogenase 2 and increased immune-responsive gene 1 and mitochondrial citrate carrier in dapagliflozin-treated mice, which contributed to the inhibitory effect of dapagliflozin on NLRP3 inflammasome activation. Furthermore, administration of cell-permeable itaconate surrogate prevented activation of NLRP3 inflammasome and protected kidney against fibrosis development. Our results identify a novel mechanism coupling metabolism and inflammation for kidney benefits of SGLT2 inhibition in progressive chronic kidney disease.

Human milk oligosaccharides (HMOs), multifunctional glycans naturally present in human milk, are known to contribute to the infant's microbiota and immune system development. However, the molecular specificity of HMOs on microbiota and associated fermentation is not yet fully understood, and is important for the development of infant formula optimum functionality.In vitro fermentation is carried out on structurally different HMOs with infant fecal inocula dominated by Bifidobacterium longum, Bifidobacterium breve, and Bacteroides. The gas, metabolite (SCFA, lactate, and succinate) profiles, and microbiota responses differ between individual microbiota inocula patterns regardless of HMO structure. In terms of HMO pairs with same sugar composition but different glycosidic bonds, gas and metabolite profiles are similar with the B. longum- and B. breve-dominated inocula. However, large individual variations are observed with the Bacteroides-dominated inocula. The microbial communities at the end of fermentation are closely related to the initial microbiota composition.The findings demonstrate that short-term in vitro fermentation outcomes largely depend on the initial gut microbiota composition more than the impact of HMO molecular specificity. These results advance the current understanding for the design of personalized infant nutritional solutions and therapies in future.

The BTBR T + Itpr3tf/J (BTBR) mouse has developmental disorders in the central nervous system and many aberrant neuroanatomical structures. However, identification of the pathological mechanisms underlying these abnormal neuroanatomical structures in the brains of BTBR mice is still lacking. Posttranslational modifications (PTMs) are known to be involved in the regulation of diverse cellular processes, and evidence shows that some types of PTMs are associated with the development of the central nervous system. In this study, we detected four novel PTMs in the cerebral cortex of BTBR mice as compared to C57BL/6 J (B6) mice using western blotting. Results revealed that lysine crotonylation and succinylation were elevated in the cerebral cortex of BTBR mice compared to levels in B6 mice. We speculate that elevated profiles of lysine crotonylation and succinylation may be involved in mechanisms related to neuroanatomical abnormalities in cerebral cortex of BTBR mice.

Gastric cancer (GC) is a malignancy of the lining of the stomach and is prone to distant metastasis, which involves a variety of complex molecules. The S100 proteins are a family of calcium‐binding cytosolic proteins that possess a wide range of intracellular and extracellular functions and play pivotal roles in the invasion and migration of tumour cells. Among these, S100A10 is known to be overexpressed in GC. Lysine succinylation, a recently identified form of protein post‐translational modification, is an important regulator of cellular processes. Here, we demonstrated that S100A10 was succinylated at lysine residue 47 (K47), and levels of succinylated S100A10 were increased in human GC. Moreover, K47 succinylation of S100A10 was stabilized by suppression of ubiquitylation and subsequent proteasomal degradation. Furthermore, carnitine palmitoyltransferase 1A (CPT1A) was found to function as a lysine succinyltransferase that interacts with S100A10. Succinylation of S100A10 is regulated by CPT1A, while desuccinylation is regulated by SIRT5. Overexpression of a succinylation mimetic mutant, K47E S100A10, increased cell invasion and migration. Taken together, this study reveals a novel mechanism of S100A10 accumulation mediated by succinylation in GC, which promotes GC progression and is regulated by the succinyltransferase CPT1A and SIRT5‐mediated desuccinylation.

Biological nitrogen fixation emerging from the symbiosis between bacteria and crop plants holds promise to increase the sustainability of agriculture. One of the biggest hurdles for the engineering of nitrogen‐fixing organisms is an incomplete knowledge of metabolic interactions between microbe and plant. In contrast to the previously assumed supply of only succinate, we describe here the CATCH‐N cycle as a novel metabolic pathway that co‐catabolizes plant‐provided arginine and succinate to drive the energy‐demanding process of symbiotic nitrogen fixation in endosymbiotic rhizobia. Using systems biology, isotope labeling studies and transposon sequencing in conjunction with biochemical characterization, we uncovered highly redundant network components of the CATCH‐N cycle including transaminases that interlink the co‐catabolism of arginine and succinate. The CATCH‐N cycle uses N2 as an additional sink for reductant and therefore delivers up to 25% higher yields of nitrogen than classical arginine catabolism—two alanines and three ammonium ions are secreted for each input of arginine and succinate. We argue that the CATCH‐N cycle has evolved as part of a synergistic interaction to sustain bacterial metabolism in the microoxic and highly acid environment of symbiosomes. Thus, the CATCH‐N cycle entangles the metabolism of both partners to promote symbiosis. Our results provide a theoretical framework and metabolic blueprint for the rational design of plants and plant‐associated organisms with new properties to improve nitrogen fixation., This study challenges the current model of nitrogen exchange in rhizobia‐legumes symbiosis and describes the CATCH‐N cycle, which operates on the provision of arginine and succinate by the plant as part of a metabolic network driving symbiotic nitrogen fixation in rhizobia.

Sarpogrelate is widely used to treat peripheral vascular disorders. However, it has been demonstrated to have a poor pharmacokinetic (PK) profile and marked within-subject variability. Here, the bioequivalence of 2 formulations of sarpogrelate (100-mg tablets) was assessed by using the reference-scaled average bioequivalence (RSABE) method, and the PK parameters were quantified in healthy Chinese subjects under fasting (n = 38) and fed (n = 35) conditions. In this open and randomized 4-way replicate study, a single dose of sarpogrelate was administered followed by a 3-day washout period. The sarpogrelate concentration in blood samples was measured by liquid chromatography-tandem mass spectrometry within 6 hours (fasting) or 10 hours (fed) of drug administration, and the PK parameters were determined by a noncompartmental model. The bioequivalence of the 2 formulations under both conditions was assessed using the ratios of ln(peak concentration [Cmax ]) and ln(area under the concentration-time curve [AUC]) within the limits based on the RSABE method. The 90% CIs for the ratios of lnCmax , lnAUC0-t , and lnAUC0-∞ were 0.8531-1.1100, 0.9616-1.0737, and 0.9550-1.0684, respectively, under fasting conditions and 0.8918-1.1076, 0.9818-1.0694, and 0.9818-1.0686, respectively, under fed conditions, which were within the RSABE acceptance limits. Food intake decreased the systemic exposure and the Cmax of sarpogrelate by 0.9-fold and 0.5-fold, respectively.

Background: High molecular weight (MW) synthetic colloids interfere with refractometry. The effect of low MW synthetic colloids on refractometry is unknown. Objectives: To investigate the effect of 6% hydroxyethyl starch 130/0.4 (HES) and 4% succinylated gelatin (GELO) on the refractometric measurement of total plasma protein (TPP) and colloid osmotic pressure (COP) in canine plasma. Methods: Heparinized plasma from 10 dogs was diluted with 0.9% saline (NaCl), HES, and GELO in ratios of plasma:fluid, 9:1, 8:2, 7:3, 6:4, and 5:5. The biuret TPP (TPPb), refractometric TPP (TPPr), and COP assays were performed for all dilutions. Agreement (bias, 95% limits of agreement (LOA)) was tested between the TPPb (NaCl) and the TPPr of the NaCl, HES, and GELO plasma dilutions, and between the TPPb (NaCl) and the TPPb of the HES and GELO plasma dilutions. Results: A small bias (0.06 g/dL, 95% LOA −0.51 to 0.39 g/dL) existed between TPPb (NaCl) and TPPr (NaCl). A large bias was found between TPPb (NaCl) and TPPr (HES) (1.38 g/dL, 95% LOA 0.30 to 3.10 g/dL), and TPPr (GELO) (1.18 g/dL, 95% LOA 0.53 to 2.88 g/dL). A small bias was found between TPPb (NaCl) and TPPb (HES) (0.08 g/dL, 95% LOA −2.04 to 2.20 g/dL), and a large bias was found between TPPb (NaCl) and TPPb (GELO) (1.00 g/dL, 95% LOA −0.59 to 2.60 g/dL). Increasing overestimation of TPPb (NaCl) by TPPr (HES and GELO) and TPPb (GELO) occurred with increasing colloid volumes. Conclusions: HES and GELO interfered with TPPr, and GELO also interfered with TPPb, in vitro. These variables should be interpreted with caution for dogs that have received these synthetic colloids.

A series of asymmetrically disubstituted diitaconate monomers is presented. Starting from itaconic anhydride, functional groups could be placed selectively at the two nonequivalent carbonyl groups. By using 2D NMR spectroscopy, it was shown that the first functionalization step occurred at the carbonyl group in the β position to the double bond. These monomers were copolymerized with N,N-dimethylacrylamide (DMAA) to yield polymer-based synthetic mimics of antimicrobial peptides (SMAMPs). They were obtained by free radical polymerization, a metal-free process, and still maintained facial amphiphilicity at the repeat unit level. This eliminates the need for laborious metal removal and is advantageous from a regulatory and product safety perspective. The poly(diitaconate-co-DMAA) copolymers obtained were statistical to alternating, and the monomer feed ratio roughly matched that of the repeat unit content of the copolymers. Investigations of varied R group hydrophobicity, repeat unit ratio, and molecular mass on antimicrobial activity against Escherichia coli and on compatibility with human keratinocytes showed that the polymers with the longest R groups and lowest DMAA content were the most antimicrobial and hemolytic. This is in agreement with the biological activity of previously reported SMAMPs. Thus, the design concept of facial amphiphilicity has successfully been transferred, but the selectivity of these polymers for bacteria over mammalian cells still needs to be optimized.

Gene deletion strategies using flux balance analysis (FBA) have improved the growth-coupled production of various compounds. However, the productivities were often below the expectation because the cells failed to adapt to these genetic perturbations. Here, we demonstrate the productivity of the succinate of the designed gene deletion strain was improved by adaptive laboratory evolution (ALE). Although FBA predicted deletions of adhE-pykAF-gldA-pflB lead to produce succinate from glycerol with a yield of 0.45 C-mol/C-mol, the knockout mutant did not produce only 0.08 C-mol/Cmol, experimentally. After the ALE experiments, the highest succinate yield of an evolved strain reached to the expected value. Genome sequencing analysis revealed all evolved strains possessed novel mutations in ppc of I829S or R849S. In vitro enzymatic assay and metabolic profiling analysis revealed that these mutations desensitizing an allosteric inhibition by L-aspartate and improved the flux through Ppc, while the activity of Ppc in the unevolved strain was tightly regulated by L-aspartate. These result demonstrated that the evolved strains achieved the improvement of succinate production by expanding the flux space of Ppc, realizing the predicted metabolic state by FBA.

The 2,5-diaminoterephthalate (DAT) structural motif is a powerful chromophore with remarkable fluorescence properties. Containing two carboxylate and two amino groups, it defines a colored molecular scaffold that allows for orthogonal functionalization with up to four different functional units. These compounds can be accessed in a remarkably simple fashion through reactions of succinyl succinates with amines, followed by aerobic oxidation, which is, from a preparative point of view, an issue of paramount importance. Even though DATs have been known since the beginning of the last century, compared to other classes of dyes they are so far underrated in the literature. This review highlights applications in life sciences and materials science. Equipped with maleimides and cyclooctyne moieties, for example, the chromophore can be covalently conjugated to biomolecules, which allows for the study of protein conformations and protein–protein interactions. In some cases, DATs serve as “turn-on” probes, because their fluorescence quantum yields are increased by orders of magnitude upon reaction with the molecular target. Additionally, DAT fluorophores exhibit efficient emission in the solid state. By choosing appropriate substituents at the amino and carboxylate moieties, the emission wavelengths can be tuned in a broad range. As nanocrystalline needles, for example, DATs can be applied as fluorescence antennas for plasmon polaritons on a gold surface.

Poly(propyl ether imine) (PETIM) dendrimers of one to three generations are used as dendritic cores to identify the influence of varying connector types that connect the dendritic core with peripheral mesogens on the emerging liquid crystalline (LC) properties. The LC properties vary in these dendritic liquid crystals, even when the dendrimer generations and thus the number of peripheral mesogenic moieties remain identical. PETIM dendrimer generations one to three, ester and amide connectors varying with succinates, phthalates, and succinamides, are studied herein. Cholesteryl moieties are installed at the peripheries through the above connectors to induce mesogenic properties. These modified dendritic liquid crystals reveal a layered mesophase structure in most ester and amide connector-derivatives, whereas a third-generation phthalate ester dendrimer favors a rectangular columnar mesophase structure. A transition from layered to a rectangular columnar structure results by a mere change in the connector varying between a succinate or succinamide or phthalate, within one particular dendrimer generation and without altering the underlying dendrimer core or the number of mesogenic moieties. The study demonstrates that in dendritic liquid crystals with essentially identical chemical constitutions, a change in the connector type connecting the mesogen with the dendrimer core is sufficient to change the mesophase structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

Succinylation of proteins is widespread, modifies both the charge and size of the molecules, and can alter their function. For example, liver mitochondrial proteins have 1,190 unique succinylation sites representing multiple metabolic pathways. Succinylation is sensitive to both increases and decreases of the NAD+ -dependent desuccinylase, SIRT5. Although the succinyl group for succinylation is derived from metabolism, the effects of systematic variation of metabolism on mitochondrial succinylation are not known. Changes in succinylation of mitochondrial proteins following variations in metabolism were compared against the mitochondrial redox state as estimated by the mitochondrial NAD+ /NADH ratio using fluorescent probes. The ratio was decreased by reduced glycolysis and/or glutathione depletion (iodoacetic acid; 2-deoxyglucose), depressed tricarboxylic acid cycle activity (carboxyethyl ester of succinyl phosphonate), and impairment of electron transport (antimycin) or ATP synthase (oligomycin), while uncouplers of oxidative phosphorylation (carbonyl cyanide m-chlorophenyl hydrazine or tyrphostin) increased the NAD+ /NADH ratio. All of the conditions decreased succinylation. In contrast, reducing the oxygen from 20% to 2.4% increased succinylation. The results demonstrate that succinylation varies with metabolic states, is not correlated to the mitochondrial NAD+ /NADH ratio, and may help coordinate the response to metabolic challenge.

In this study, Ag-ZnO nanophotocatalyst has been synthesized through microemulsion technique and the effect of silver modification on ZnO nanorods has been evaluated. The photocatalytic activity of nanocatalyst was examined by degradation of Acid Yellow 23 (AY23) as a model of mono azo dye under UV illumination. Ag-ZnO catalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDXS) and diffuse reflectance spectroscopy (DRS) analysis. The degradation of AY23 was studied under different operational parameters. Results show that the photocatalytic reaction followed the pseudo-first-order kinetic. The highest photocatalytic degradation of 20 mg/L AY23 dye solution under UV irradiation (light intensity = 50 W/m2 , [Ag-ZnO]0 = 400 mg/L with 2 wt% Ag doped ZnO, calcined at 450 °C) was about 93.3% during 30 minutes of reaction that shows an enhancement in comparison to pure ZnO which was 65.48%.

Itaconic acid (IA) is a naturally occurring dicarboxylic acid with applications in the manufacture of polymers. IA can be produced by fermentation using the fungi Aspergillus terreus or Ustilago maydis as biocatalysts. Indirect evidence has suggested that the mitochondrial carriers U. maydis Um_Mtt1 and A. terreus At_MttA export mitochondrially synthesized cis-aconitate to the cytosol for IA synthesis using malate as a countersubstrate. Here, by assaying the transport features of recombinant Um_Mtt1 and At_MttA in reconstituted liposomes, we find that both proteins efficiently transport cis-aconitate, but malate is well transported only by Um_Mtt1 and 2-oxoglutarate only by At_MttA. Bioinformatic analysis shows that Um_Mtt1 and At_MttA form a distinctive mitochondrial carrier subfamily. Our data show that although fulfilling the same physiological task, Um_Mtt1 and At_MttA have different biochemical features.

Macrophages play a central role in innate immunity as the first line of defense against pathogen infection. Upon exposure to inflammatory stimuli, macrophages rapidly respond and subsequently undergo metabolic reprogramming to substantially produce cellular metabolites such as itaconate. As a derivate of the tricarboxylic acid cycle, itaconate is derived from the decarboxylation of cis-aconitate mediated by immunoresponsive gene 1 in the mitochondrial matrix. It is well known that itaconate has a direct antimicrobial effect by inhibiting isocitrate lyase. Strikingly, two recent studies published in Nature showed that itaconate markedly decreases the production of proinflammatory mediators in lipopolysaccharide-treated macrophages and ameliorates sepsis and psoriasis in animal models, revealing a novel biological action of itaconate beyond its regular roles in antimicrobial defense. The mechanism for this anti-inflammatory effect has been proposed to involve the inhibition of succinate dehydrogenase, blockade of IκBζ translation and activation of Nrf2. These intriguing discoveries provide a new explanation for how macrophages are switched from a pro- to an anti-inflammatory state to limit the damage and facilitate tissue repair under proinflammatory conditions. Thus, the emerging effect of itaconate as a crucial determinant of macrophage inflammation has important implications in further understanding cellular immunometabolism and developing future therapeutics for the treatment of inflammatory diseases. In this review, we focus on the roles of itaconate in controlling the inflammatory response during macrophage activation, providing a rationale for future investigation and therapeutic intervention.

The interfacial properties of pure reverse micelles (RMs) are a consequence of the magnitude and nature of noncovalent interactions between confined water and the surfactant polar head. Addition of a second surfactant to form mixed RMs is expected to influence these interactions and thus affect these properties at the nanoscale level. Herein, pure and mixed RMs stabilized by sodium 1,4-bis-2-ethylhexylsulfosuccinate and tri-n-octyl phosphine oxide (TOPO) surfactants in n-heptane were formulated and studied by varying both the water content and the TOPO mole fraction. The microenvironment generated was sensed by following the solvatochromic behavior of the 1-methyl-8-oxyquinolinium betaine probe and (31) P NMR spectroscopy. The results reveal unique properties of mixed RMs and we give experimental evidence that free water can be detected in the polar core of the mixed RMs at very low water content. We anticipate that these findings will have an impact on the use of such media as nanoreactors for many types of chemical reactions, such as enzymatic reactions and nanoparticle synthesis.

The front cover picture, provided by Carla Carfagna et al., shows the first example of an oxidative bis‐alkoxycarbonylation of acrylic esters and acrylic amides, leading to 2‐EWG‐substituted succinates. Despite the low reactivity of electron‐deficient olefins in carbonylation reactions, the aryl α‐diimine palladium(II) catalyst is able to promote the carbonylation of both the β‐ and the generally non‐reactive α‐positions of electron‐poor alkenes, under mild reaction conditions (PCO=4 bar, T=20 °C). Further details of this work can be found in the full paper on pages 533–544

The crystal structures of carboxypeptidase T (CpT) complexes with phenylalanine and arginine substrate analogs - benzylsuccinic acid and (2-guanidinoethylmercapto)succinic acid - were determined by the molecular replacement method at resolutions of 1.57 Å and 1.62 Å to clarify the broad substrate specificity profile of the enzyme. The conservative Leu211 and Leu254 residues (also present in both carboxypeptidase A and carboxypeptidase B) were shown to be structural determinants for recognition of hydrophobic substrates, whereas Asp263 was for recognition of positively charged substrates. Mutations of these determinants modify the substrate profile: the CpT variant Leu211Gln acquires carboxypeptidase B-like properties, and the CpT variant Asp263Asn the carboxypeptidase A-like selectivity. The Pro248-Asp258 loop interacting with Leu254 and Tyr255 was shown to be responsible for recognition of the substrate's C-terminal residue. Substrate binding at the S1' subsite leads to the ligand-dependent shift of this loop, and Leu254 side chain movement induces the conformation rearrangement of the Glu277 residue crucial for catalysis. This is a novel insight into the substrate selectivity of metallocarboxypeptidases that demonstrates the importance of interactions between the S1' subsite and the catalytic center.

Fumaramic acid derivatives can be converted into their cis isomer maleamic acid derivatives under UV illumination, and these maleamic acid derivatives show pH-responsive degradability at acidic pH only after the preceding photoisomerization. The rate of the tandem photoisomerization-degradation of fumaramic acid derivatives can be finely controlled by changing the substituents on the double bond. Photoisomerization-based unlocking of the pH-responsive degradability of fumaramic acid derivatives has strong potential for the development of multisignal-responsive smart materials in biomedical applications.

Asymmetric hydrogenation of maleic and fumaric acid derivatives with iridium catalysts based on N,P ligands provides an efficient route to chiral enantioenriched succinates. A new catalyst derived from a 2,6-difluorophenyl-substituted pyridine-phosphinite ligand was developed and enables the conversion of a wide range of 2-alkyl and 2-arylmaleic acid diesters into the corresponding succinates in high enantiomeric purity. Mixtures of cis/trans substrates can be hydrogenated in an enantioconvergent fashion with high enantioselectivity, and further enhances the scope of this transformation. The products are valuable chiral building blocks with a structural motif found in many bioactive compounds, such as metalloproteinase inhibitors.

Synthetic polyester elastomeric constructs have become increasingly important for a range of healthcare applications, due to tunable soft elastic properties that mimic those of human tissues. A number of these constructs require intricate mechanical design to achieve a tunable material with controllable curing. Here, the synthesis and characterization of poly(itaconate-co-citrate-co-octanediol) (PICO) is presented, which exhibits tunable formation of elastomeric networks through radical crosslinking of itaconate in the polymer backbone of viscous polyester gels. Through variation of reaction times and monomer molar composition, materials with modulation of a wide range of elasticity (36-1476 kPa) are generated, indicating the tunability of materials to specific elastomeric constructs. This correlated with measured rapid and controllable gelation times. As a proof of principle, scaffold support for cardiac tissue patches is developed, which presents visible tissue organization and viability with appropriate elastomeric support from PICO materials. These formulations present potential application in a range of healthcare applications with requirement for elastomeric support with controllable, rapid gelation under mild conditions.

The oxidation of 1,4-butanediol and butyrolactone have been investigated by using supported gold, palladium and gold-palladium nanoparticles. The products of such reactions are valuable chemical intermediates and, for example, can present a viable pathway for the sustainable production of polymers. If both gold and palladium were present, a significant synergistic effect on the selective formation of dimethyl succinate was observed. The support played a significant role in the reaction, with magnesium hydroxide leading to the highest yield of dimethyl succinate. Based on structural characterisation of the fresh and used catalysts, it was determined that small gold-palladium nanoalloys supported on a basic Mg(OH)2 support provided the best catalysts for this reaction.

Background: 5-hydroxytryptamine (5-HT) receptors are upregulated in activated hepatic stellate cells (HSCs), and are therefore thought to play an important role in their activation. Aim: The aim of this study was to determine whether 5-HT2A receptor antagonists affect the activation or apoptosis of HSCs in vitro and/or in vivo. Methods: For the in vitro experiments, the viability, apoptosis and wound healing ability of LX-2 cells were examined after treatment with various 5-HT2A receptor antagonists. Levels of HSC activation markers (procollagen type I, a-SMA, TGF-b and Smad 2/3) were measured. For in vivo experiments, rats were divided into three groups: (i) a control group, (ii) a disease group, in which cirrhosis was induced by thioacetamide (iii) a treatment group, in which cirrhosis was induced and a 5-HT2A receptor antagonist (sarpogrelate, 30 mg/kg) was administered. Results: 5-HT2A, but not 5-HT2B receptor mRNA increased with time upon HSC activation. 5-HT2A receptor antagonists (ketanserin and sarpogrelate) inhibited viability and wound healing in LX-2 cells and induced apoptosis. Expression of a-SMA and procollagen type I was also inhibited. In the in vivo study, lobular inflammation was reduced in the sarpogrelate-treated group, but there was only slight and statistically insignificant attenuation of periportal fibrosis. Expression of a-SMA, TGF-b and Smad 2/3 was also reduced in the treatment group. Conclusions: 5-HT2A receptor antagonists can reduce inflammation and the activation of HSCs in this cirrhotic model. The total amount of 5-hydroxytryptamine (5-HT, also known as serotonin) in the human body is around 10 mg, with approximately 95% of this in the gastrointestinal tract and the remaining 5% in the brain (1). It is secreted by enterochromaffin cells into the blood, where it is actively taken up by platelets (2). It is involved in a variety of functions such as regulation of emotion, appetite, sleep, gastrointestinal motility, secretion, vascular contraction, relaxation and platelet aggregation (3, 4). 5-HT has an important role in proliferation of hepatocytes as reported in recent studies. 5-HT secreted from platelets was found to play an important role in the regeneration of hepatocytes (5, 6). Recently, Nagao et al. demonstrated an involvement of 5-HT in the thrombocytotic effect in splenectomy-induced liver regeneration, and in the amelioration of fibrosis in rat liver with secondary biliary cirrhosis (6). Tian et al. showed that 5-HT could prevent small-for-size liver graft failure in mice by enhancing hepatocyte regeneration via the IL-6 pathway (7). These studies are consistent with previous work demonstrating that platelets promote liver regeneration (5). These evidences indicate that 5-HT has protective role against hepatic ischaemic and reperfusion injury. Until now most studies have focused on the promotion of hepatic regeneration by 5-HT via preservation of the hepatic microcirculation and IL-6 pathway, but 5-HT has other effects on the liver. For example, the increased levels of reactive oxygen species produced by 5-HT degradation aggravate steatohepatitis (8), and expression of 5-HT receptors is upregulated in activated HSCs (9). This interesting pleiotropic influence of 5-HT on the liver suggested that comprehensive investigation of its cell type specific expression patterns and its roles in various liver conditions would be valuable, along with studies involving selective blockade. There are as yet no published data on the effects of selective 5-HT blockers on in vitro or in vivo hepatic stellate cell (HSC) activation. Renal mesangial cells, which have similar properties to HSCs, produce increased levels of TGF-b and connective tissue growth factor in response to activation of 5-HT2A receptors (10–12). 5-HT2 receptors are also

A one-pot, convergent method for the synthesis of 5,6-dihydroquinolines by simple mixing of two equivalents of acyclic α,α-dicyanoolefins and one equivalent of acetylenic ester in the presence of Et3N is described. Three new C–C and one C–N bonds are created in this operation. In the same reaction, cyclic α,α-dicyanoolefins led to the formation of succinates. Further hydrolysis and decarboxylation of 5,6-dihydroquinoline led to quinoline.

A new N-hydantoin-containing biocompatible and enzymatically degradable polyester with antibacterial properties is presented. Different polyesters of dimethyl succinate, 1,4-butanediol, and 3-[N,N-di(β-hydroxyethyl)aminoethyl]-5,5-dimethylhydantoin in varying molar ratios are prepared via two-step melt polycondensation. The antibacterially active N-halamine form is obtained by subsequent chlorination of the polyesters with sodium hypochlorite. Chemical structures, thermal properties, and spherulitic morphologies of the copolymers are studied adopting FT-IR, NMR, TGA, DSC, WAXD, and POM. The polyesters exhibit antibacterial activity against Escherichia coli. The adopted synthetic approach can be transferred to other polyesters in a straightforward manner.

Beverage emulsions containing flavor oils that have a relatively high water-solubility are unstable to droplet growth due to Ostwald ripening. The aim of this study was to improve the stability of model beverage emulsions to this kind of droplet growth by incorporating poorly water-soluble triglyceride oils. High pressure homogenization was used to prepare a series of 5 wt% oil-in-water emulsions stabilized by modified starch that had different lipid phase compositions (orange oil : corn oil). Emulsions prepared using only orange oil as the lipid phase were highly unstable to droplet growth during storage, which was attributed to Ostwald ripening resulting from the relatively high water-solubility of orange oil. Droplet growth could be effectively inhibited by incorporating ≥ 10% corn oil into the lipid phase prior to homogenization. In addition, creaming was also retarded because the lipid phase density was closer to that of the aqueous phase density. These results illustrate a simple method of improving the physical stability of orange oil emulsions for utilization in the food, beverage, and fragrance industries.

An experimental approach was developed to determine the intrinsic thermolysis rate constants of the central carbon–carbon bond during the dl/meso isomerization of diethyl 2,3-dicyano-2,3-di(p-substituted phenyl)succinates (G=H, Me, OMe, Cl, and NO2) at temperatures ranging from 80 to 120 °C. The obtained rate constants are significantly affected by the polarity of the para substituents, in sharp contrast to their negligible effects on the dl/meso isomerization equilibrium constants. Moreover, the substituent effects on the activation enthalpies can be linearly correlated with the Hammett substituent resonance constants and the homolytic dissociation enthalpies (bond dissociation energies) of the benzylic C–H bonds of ethyl 2-cyano-2-(p-substituted phenyl)acetates. Copyright © 2011 John Wiley & Sons, Ltd.

Summary Diverse microorganisms have been described to degrade petroleum hydrocarbons anaerobically. Strains able to utilize n-alkanes do not grow with aromatic hydrocarbons, whereas strains able to utilize aromatic hydrocarbons do not grow with n-alkanes. To investigate this specificity in more detail, three anaerobic n-alkane degraders (two denitrifying, one sulfate-reducing) and eight anaerobic alkylbenzene degraders (five denitrifying, three sulfate-reducing) were incubated with mixtures of n-alkanes and toluene. Whereas the toluene degradationers formed only the characteristic toluene-derived benzylsuccinate and benzoate, but no n-alkane-derived metabolites, the n-alkane degraders formed toluene-derived benzylsuccinate, 4-phenylbutanoate, phenylacetate and benzoate besides the regular n-alkane-derived (1-methylalkyl)succinates and methyl-branched alkanoates. The co-metabolic conversion of toluene by anaerobic n-alkane degraders to the level of benzoate obviously follows the anaerobic n-alkane degradation pathway with C-skeleton rearrangement and decarboxylation rather than the β-oxidation pathway of anaerobic toluene metabolism. Hence, petroleum-derived aromatic metabolites detectable in anoxic environments may not be exclusively formed by genuine alkylbenzene degraders. In addition, the hitherto largely unexplored fate of fumarate hydrogen during the activation reactions was examined with (2,3-2H2)fumarate as co-substrate. Deuterium was completely exchanged with hydrogen at the substituted carbon atom (C-2) of the succinate adducts of n-alkanes, whereas it is retained in toluene-derived benzylsuccinate, regardless of the type of enzyme catalysing the fumarate addition reaction.