The complexation of boric acid (BA) with various α-hydroxycarboxylic acids (HCAs) was examined by analyzing the change in the optical rotation after the addition of BA to aqueous HCA solutions, and ...the catalytic properties of the complexes were examined by catalyzing the esterification of the HCAs. The absolute values of the optical rotation of the HCAs increased with increasing BA-to-HCA molar ratio, and the rate of change of the optical rotation gradually decreased as the BA-to-HCA molar ratio increased, reaching a minimum value at a molar ratio of approximately three. As a catalyst, BA could catalyze the acetylation of hydroxyl groups in addition to the esterification of HCAs. Compared to the conventional synthesis routes of ATBC and ATOC, a synthesis route with BA as the catalyst allowed for a lower frequency of catalyst separation and replacement while providing light-colored products. BA could catalyze the formation of triethyl citrate, and the yield of triethyl citrate reached 93.8%. BA could also catalyze the reaction between malic acid and pinene to produce borneol malate. After saponification of borneol malate, borneol was obtained with a yield of 39%.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Significant β-hydroxy functionalized derivatives including nitroaldols, β-hydroxy nitriles and β-hydroxy carboxylic acids were successfully prepared, for the first time, by catalytic use of deep ...eutectic solvents (DES). This paper explores the versatility and effectiveness of DES as catalyst in three different carbon–carbon bond formation reactions. The uniqueness of this catalyst lies in its simplicity since it avoids expensive catalysts and multi-step synthesis as reported in literature. The compounds, which are potent intermediates for innumerable useful products, were synthesized in excellent yields within very short reaction times. The catalyst prepared from choline chloride and urea, is biodegradable, non-toxic, cost-effective and recyclable.
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► Catalytic role of deep eutectic solvent in C-C bond formation reaction is explored. ► The method gave excellent yields in lesser reaction times. ► Multi-step synthesis and expensive catalysts were avoided. ► The catalyst is recyclable with no loss in activity even after 4 runs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lactate is an intriguing molecule with emerging physiological roles in the brain. It has beneficial effects in animal models of acute brain injuries and traumatic brain injury or subarachnoid ...hemorrhage patients. However, the mechanism by which lactate provides protection is unclear. While there is evidence of a metabolic effect of lactate providing energy to deprived neurons, it can also activate the hydroxycarboxylic acid receptor 1 (HCAR1), a Gi-coupled protein receptor that modulates neuronal firing rates. After cerebral hypoxia-ischemia, endogenously produced brain lactate is largely increased, and the exogenous administration of more lactate can decrease lesion size and ameliorate the neurological outcome. To test whether HCAR1 plays a role in lactate-induced neuroprotection, we injected the agonists 3-chloro-5-hydroxybenzoic acid and 3,5-dihydroxybenzoic acid into mice subjected to 30-min middle cerebral artery occlusion. The
in vivo
administration of HCAR1 agonists at reperfusion did not appear to exert any relevant protective effect as seen with lactate administration. Our results suggest that the protective effects of lactate after hypoxia-ischemia come rather from the metabolic effects of lactate than its signaling through HCAR1.
•DMF may act in neurodegeneration and inflammation by activating the Nrf2 pathway.•DMF and MMF downregulates the immune response through HCA2/GPR109A pathway.•Nrf2 and HCA2/GPR109A pathways ...activation may explain DMF's efficacy and safety profile.
The mechanisms of action of dimethyl fumarate (DMF), and its metabolite, monomethyl fumarate (MMF), for the treatment of multiple sclerosis are not completely elucidated.
To discuss the role of DMF/MMF-induced hydroxycarboxylic acid receptor 2 (HCA2/GPR109A) pathway activation in the immune response and treatment of MS.
A narrative (traditional) review of the current literature.
Studies have shown that binding of DMF/MMF to HCA2 on dendritic cells inhibits the production of pro-inflammatory cytokines in vitro and in MS murine models. Evidence suggests that activation of HCA2 expressed in immune cells and gut epithelial cells by DMF/MMF, may induce anti-inflammatory responses in the intestinal mucosa.
Although the DMF/MMF mechanism of action remains unclear, evidence suggests that the activation of HCA2/GPR109A pathway downregulates the immune response and may activate anti-inflammatory response in the intestinal mucosa, possibly leading to reduction in CNS tissue damage in MS patients.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
α,ω‐Dicarboxylic acids are valuable precursors in various chemical industries and have recently been produced using biotechnological methods to overcome the limitations of chemical synthesis. ...Nonanedioic acid, decanedioic acid, undecanedioic acid, and dodecanedioic acid have been produced at high concentrations from ω‐hydroxycarboxylic acids using engineered biocatalysts. However, no study has been attempted on the efficient production of pentadecanedioic acid. Here, the production of pentadecanedioic acid from 15‐hydroxypentadecanoic acid was carried out with alcohol dehydrogenases (ADHs), aldehyde dehydrogenases (ALDHs), and NAD(P)H oxidases, including NAD(P)H flavin oxidoreductase (NFO), that used a co‐factor regeneration system, derived from several species and expressed in Escherichia coli. Among the enzymes, Kangiella koreensis ADH (KkADH), Geobacillus kaustophilus ALDH (GkALDH), and Deinococcus radiodurans NFO (DrNFO) were selected because they had the highest activity. E. coli expressing pRSF‐DrNFO and pACYC‐KkADH/GkALDH as the best distribution of three genes in two plasmids was used as a biocatalyst to produce pentadecanedioic acid. The optimal conditions for producing pentadecanedioic acid from 15‐hydroxypentadecanoic acid by the biocatalyst were pH 8.0, 35°C, 5% (v/v) methanol, 40 g L−1 cells, and 60 mM 15‐hydroxypentadecanoic acid with agitation at 250 rpm. Under these optimized conditions, 57.4 mM pentadecanedioic acid was produced after 3 h, with a molar yield of 95.6% and a productivity of 19.1 mM h−1. The molar yield and concentration of pentadecanedioic acid showed the highest values among the reported biotechnological production of pentadecanedioic acid.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Herein, we report a straightforward synthesis of valuable α‐hydroxycarboxylic acid molecules via an acceptorless dehydrogenative coupling of ethylene glycol and primary alcohols. A bench‐stable ...manganese complex catalyzed the reaction, which is scalable, with the product being isolated with high yields and selectivities under mild conditions. The protocol is environmentally benign, producing water and hydrogen gas as the only byproducts. Methanol can also be used as a C1 source for producing the platform molecule lactic acid, with a high turnover of >104. The methodology was also used to functionalize alcohols derived from natural products and fatty acids. Furthermore, it was applied for synthesizing α‐amino acid, α‐thiocarboxylic acid, and several drugs and bioactive molecules, including endogenous metabolites, Danshensu, Enalapril, Lisinopril, and Rosmarinic acid. Preliminary mechanistic studies were performed to shed light on the mechanism involved in the reaction.
A versatile synthesis of highly demanded α‐hydroxycarboxylic acids via dehydrogenative coupling of two feedstock chemicals, ethylene glycol, and primary alcohols, is reported. An Earth's abundant metal complex catalyzes the reaction with high yields and selectivities. Water and hydrogen gas are produced as the sole byproducts.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Solvent-induced chirality switching in the optical resolution of racemic tropic acid (TA) with (1R,2S)-2-amino-1,2-diphenylethanol has been demonstrated. Recrystallization of the diastereomeric salt ...mixture from i-PrOH or EtOH afforded the (S)-TA salt, while the (R)-TA salt was deposited from 1,4-dioxane and water-enriched alcohol solutions. Dual chirality switching was achieved by using two different types of solvents. The X-ray crystal structures of both diastereomeric salts showed that incorporation of the crystallization solvent played a crucial role in stabilizing each diastereomeric salt crystal. The mechanism of chirality switching has been discussed on the basis of the relative stability of the salt, as deduced from their structures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Dimethyl fumarate (DMF), recently approved as an oral immunomodulatory treatment for relapsing-remitting multiple sclerosis (MS), metabolizes to monomethyl fumarate (MMF) which crosses the ...blood–brain barrier and has demonstrated neuroprotective effects in experimental studies. We postulated that MMF exerts neuroprotective effects through modulation of microglia activation, a critical component of the neuroinflammatory cascade that occurs in neurodegenerative diseases such as MS. To ascertain our hypothesis and define the mechanistic pathways involved in the modulating effect of fumarates, we used real-time PCR and biochemical assays to assess changes in the molecular and functional phenotype of microglia, quantitative Western blotting to monitor activation of postulated pathway components, and ex vivo whole-cell patch clamp recording of excitatory post-synaptic currents in corticostriatal slices from mice with experimental autoimmune encephalomyelitis (EAE), a model for MS, to study synaptic transmission. We show that exposure to MMF switches the molecular and functional phenotype of activated microglia from classically activated, pro-inflammatory type to alternatively activated, neuroprotective one, through activation of the hydroxycarboxylic acid receptor 2 (HCAR2). We validate a downstream pathway mediated through the AMPK–Sirt1 axis resulting in deacetylation, and thereby inhibition, of NF-κB and, consequently, of secretion of pro-inflammatory molecules. We demonstrate through ex vivo monitoring of spontaneous glutamate-mediated excitatory post-synaptic currents of single neurons in corticostriatal slices from EAE mice that the neuroprotective effect of DMF was exerted on neurons at pre-synaptic terminals by modulating glutamate release. By exposing control slices to untreated and MMF-treated activated microglia, we confirm the modulating effect of MMF on microglia function and, thereby, its indirect neuroprotective effect at post-synaptic level. These findings, whereby DMF-induced activation of a new HCAR2-dependent pathway on microglia leads to the modulation of neuroinflammation and restores synaptic alterations occurring in EAE, represent a possible novel mechanism of action for DMF in MS.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Scalable protocols of straightforward synthesis of enantiomeric γ‐(acyloxy)carboxylic acids and γ‐lactones are presented. The key step is lipase‐catalyzed stereoselective acylation of ...γ‐hydroxycarboxylic acid sodium salt in organic solvent followed by acidification of the product, extraction and acidic relactonization of the unreacted enantiomer. The mixture of γ‐(acyloxy)carboxylic acid and γ‐lactone is separated either by extraction with solution of sodium bicarbonate or by distillation. A switch of enantioinduction of Candida antarctica lipase B along homologous nucleophiles from R configuration of γ‐hydroxyhexanoic acid salt to S configuration of the C7 and longer‐chain homologues has been disclosed. Both enantiomers of γ‐(acyloxy)pentanoic acids; γ‐(acetyloxy)octanoic and ‐nonanoic acids with S configuration; (1S,5R)‐5‐(chloroacetyloxy)cyclopent‐2‐en‐1‐ylacetic acid and enantiomeric γ‐lactones derived from them were prepared with e. r. >98.5/1.5. The rates of acylation of C5 to C9 homologous salts differ by three orders of magnitude but remain applicable for preparative synthesis by variation of the enzyme loading and reaction time.
The synthesis of enantiomeric γ‐(acyloxy)carboxylic acids and γ‐lactones from racemic γ‐lactones is reported, which involves lipase‐catalyzed acylation of γ‐hydroxycarboxylic acid sodium salts in organic solvent followed by relactonization of the unreacted enantiomer. The products were separated by extraction, no column chromatography is needed.
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BFBNIB, FZAB, GIS, IJS, KILJ, OILJ, SBCE, SBMB, UPUK
Monomethyl fumarate (MMF), metabolite of dimethyl fumarate (DMF), an immunosuppressive drug approved for the treatment of multiple sclerosis (MS), is a potent agonist for hydroxycarboxylic acid ...receptor 2 (HCAR2), eliciting signals that dampen cell activation or lead to inflammation such as the skin flushing reaction that is one of the main side effects of the treatment, together with gastrointestinal inflammation. Our aim is to further understand the molecular basis underlying these differential effects of the drug. We have used wild-type and HCAR2 knock-out mice to investigate,
in vitro
and
ex vivo
under steady-state and pathological conditions, the HCAR2-mediated signaling pathways activated by MMF in dendritic cells (DC), which promote differentiation of T cells, and in intestinal epithelial cells (IEC) where activation of a pro-inflammatory pathway, such as the cyclooxygenase-2 pathway involved in skin flushing, could underlie gastrointestinal side effects of the drug. To understand how DMF treatment might impact on gut inflammation induced by experimental autoimmune encephalomyelitis (EAE), the animal model for MS, we have used 3D X-ray phase contrast tomography and flow cytometry to monitor possible intestinal alterations at morphological and immunological levels, respectively. We show that HCAR2 is a pleiotropically linked receptor for MMF, mediating activation of different pathways leading to different outcomes in different cell types, depending on experimental
in-vitro
and
in-vivo
conditions. In the small intestine of EAE-affected mice, DMF treatment affected migration of tolerogenic DC from lamina propria to mesenteric lymph nodes, and/or reverted their profile to pro-inflammatory, probably as a result of reduced expression of aldehyde dehydrogenase and transforming growth factor beta as well as the inflammatory environment. Nevertheless, DMF treatment did not amplify the morphological alterations induced by EAE. On the basis of our further understanding of MMF signaling through HCAR2, we suggest that the pleiotropic signaling of fumarate
via
HCAR2 should be addressed for its pharmaceutical relevance in devising new lead compounds with reduced inflammatory side effects.
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