Search Results (130)

In 2019, carbamates derived from 3-hydroxypyridine were classified as nerve agents and subsequently included in the Annex on Chemicals by the Conference of the States Parties. Herein, we describe the preparation of a structural simulant of this class of compounds, 10-hydroxy-N,N-dimethyl-N-((3-(tosyloxy)pyridin-2-yl)methyl)decan-1-aminium bromide. The compound was synthesized via tosylation of 2-((N,N-dimethylamino)methyl)pyridin-3-ol with tosyl chloride in the presence of sodium hydride, followed by alkylation of the resulting ((N,N-dimethylamino)methyl)pyridin-3-yl 4-methylbenzenesulfonate with 10-bromodecan-1-ol. Full article

Lanthanide-based single-molecule magnets (Ln-SMMs) showing stimuli-responsive changes in photoluminescence (PL) and magnetic properties are attractive for their potential applications in information storage and molecular devices. In this work, we report two mononuclear complexes, namely, Dy(SCN)₂(NO₃)(Cl-depma)₂(4-hpy)₂ (Dy-Cl) and Dy(SCN)₂(NO₃)(Br-depma)₂(4-hpy)₂ (Dy-Br), where X-depma represents 10-X-9-diethylphosphinomethylanthracene (X = Cl, Br) and 4-hpy is 4-hydroxypyridine. Both contain face-to-face π-π-interacted anthracene rings and exhibit yellow-green excimer emission. Unlike the other related Dy–anthracene complexes without a halogen substituent, Dy-Cl and Dy-Br cannot undergo photocycloaddition reaction under UV-light irradiation. However, they exhibited remarkable grinding-induced changes in luminescence. Magnetic studies revealed that Dy-Cl and Dy-Br show SMM behavior under zero dc field with the effective energy barriers (U_eff/k_B) of 259 K and 264 K, respectively. We also investigated the effect of pressure on the magnetic properties of Dy-Br and observed a reduction in the magnetization value, narrowing of the butterfly-shaped hysteresis loop, and acceleration of the magnetic relaxation under 1.09 GPa. The results demonstrate that introducing a halogen substituent into an anthracene group may pose significant influences on the photophysical and photochemical properties of the complexes. In addition, pressure may be a promising external stimulus to modulate the PL and SMM behaviors of Dy–anthracene complexes. Full article

The reaction of CoCl₂ · 6H₂O with 6-chloro-2-hydroxypyridine (Hchp) and 1,10-phenanthroline (phen) afforded the complex [Co(chp)₂(phen)] (1). Although this complex has been previously reported, it was obtained in this work under mild conditions (in acetonitrile at room temperature) and characterized for the first time by single-crystal X-ray diffraction. The use of Co(F₃CCOO)₂ · 4H₂O under similar conditions yielded a new trinuclear molecular complex [Co₃(chp)₂(F₃CCOO)₄(phen)₂] (2). According to X-ray diffraction data, the cobalt(II) ions in complexes 1 and 2 are located in an octahedral environment (coordination number CN_Co = 6). As an ambidentate ligand, Hchp exhibits different types of coordination modes in the resulting complexes 1 and 2. Additional stabilization of molecules in the crystal is achieved by π-π stacking between aromatic systems of coordinated phen ligands. The cytotoxic activity of 1 and [CoCl₂(phen)₂] · 1.5MeCN (3) against a panel of human cancer cell lines (SKBR3, HCT116, A549) and normal dermal fibroblasts (HDF) was evaluated using the MTT assay. Complex 3 demonstrated cytotoxic activity against the HCT116 cell line comparable to that of cisplatin, indicating its potential as a promising antitumor agent. Full article

The endometrial immune response in postpartum cows is key to maintaining uterine health and preventing inflammatory diseases such as metritis and endometritis. Appropriate management strategies and diets that enhance the immune response are crucial during the transition period; therefore, diets rich in omega-3 fatty acids have been proposed for their potential beneficial effects on cows. Docosahexaenoic acid (DHA) is an omega-3 fatty acid with anti-inflammatory effects in immune cells; however, its effects on bovine endometrial immunity are not fully known. This study aimed to determine the effect of DHA on the inflammatory response in bovine endometrial (BEND) cells. BEND cells were incubated with DHA without or with lipopolysaccharide (LPS), and the mRNA expressions of prostaglandin-endoperoxide synthase 2 (PTGS2), interleukin (IL)-6, and CXCL8 were analyzed using RT-qPCR. The protein amount of IL-6, or CXCL8, and Resolvin D1 (RvD1) in the cell culture medium were analyzed using ELISA. DHA significantly reduced the expression of LPS-induced IL-6 and PTGS2 but increased LPS-induced CXCL8 expression. In addition, DHA reduced LPS-induced ERK1/2 and Akt phosphorylation, as assessed by immunoblotting. DHA increased the production of RvD1, a metabolite of DHA, at 8 and 24 h. In addition, RvD1 reduced LPS-induced CXCL8 production and increased the phosphorylation of ERK1/2 and Akt. Finally, changes in metabolite levels, such as an increase in 2-hydroxypyridine in DHA-treated cells, were obtained using a metabolomic assay. In conclusion, DHA reduced IL-6 and PTGS2 mRNA expression and IL-6 protein release and increased RvD1 levels in bovine endometrial cells, which suggest that DHA could have beneficial effects on endometrial immunity. The increase in CXCL8 mRNA expression and protein release induced by DHA remains to be studied; however, it could play a role in the innate defensive mechanisms of phagocytes. Full article

The efficient recovery of rhenium (Re), a critical metal in high-tech industries, is essential to address its growing demand and reduce reliance on primary mining. In this study, we developed novel anion-exchange resins for the selective adsorption and recovery of Re(VII) ions from acidic solutions, simulating industrial by-products. The resins were synthesized from a vinylbenzyl chloride-co-divinylbenzene copolymer modified with aliphatic, heterocyclic, and aromatic weakly basic amines, selected from among bis(3-aminopropyl)amine (BAPA), 1-(2-pyrimidinyl)piperazine (PIP), thiosemicarbazide (TSC), 2-amino-3-hydroxypyridine (AHP), 1-(2-hydroxyethyl)piperazine (HEP), 4-amino-2,6-dihydroxypyrimidine (AHPI), and 2-thiazolamine (TA). The adsorption of Re on BAPA, PIP, and HEP resins obeyed the Langmuir model, and the resins exhibited high adsorption capacities, with maximum values reaching 435.4 mg Re g⁻¹ at pH 6. Furthermore, strong selectivity for ReO₄⁻ ions over competing species, including Mo, Cu, and V, was noted in solutions simulating the leachates of the by-products of Cu-Mo ores. Additionally, complete elution of Re was possible. The developed resins turned out to be highly suitable for the continuous-flow-mode adsorption of ReO₄⁻, revealing outstanding adsorption capacities before reaching column breakthrough. In this context, the novel anion-exchange resins developed offer a reference for further Re recovery strategies. Full article

Two hydrazone Schiff base-bridging ligands with different heterocycles {2-[(E)-(5-chloro-2-hydroxyphenyl)methylidene]diazanyl}(pyrazine-2-yl)methanone (H₂L_Schiff-1) and (E)-N′-(2-hydroxy-3-methoxybenzylidene)nicotinohydrazide (H₂L_Schiff-2) together with 1,3-di(2-pyridyl)-1,3-propanedione (Hdpp) were chosen to construct two new Dy₂ complexes, [Dy₂(L_Schiff-1)₂(DMF)₂(dpp)₂]·0.5DMF (1) and [Dy₂(L_Schiff-2)₂(DMF)₂(dpp)₂]·2DMF (2). Although the [N₂O₆] coordination spheres are observed for the Dy³⁺ ions in 1 and 2, their coordination configurations have some differences (both the biaugmented trigonal prism and the Snub diphenoid J84 in 1 and only the biaugmented trigonal prism in 2). Magnetic research revealed that both 1 and 2 possess ferromagnetic interactions between two Dy³⁺ ions and perform as zero-field single-molecule magnets, with U_eff/k values of 49.7 K at 0 Oe for 1 and 151.8 K at 0 Oe for 2. This work suggests that the heterocycle groups (pyrazine vs. pyridine) on the hydrazone Schiff base-bridging ligands have effects on the SMM properties of 1 and 2. Full article

The reaction of CuCl₂∙2H₂O, (E)-2-hydroxy-1,2-di(pyridin-2-yl)ethanone oxime (α-pyroxH₂) and Et₃N in refluxing MeOH gave complex [Cu₁₂Cl₁₂(mpydol)₄(pydox)₂(MeOH)₄] (1), where mpydol²⁻ is the dianion of 1,2-dimethoxy-1,2-di(pyridin-2-yl)ethane-1,2-diol and pydox²⁻ is the dianion of (E,E)-1,2-di(pyridin-2-yl)ethanedione dioxime. “Blind” experiments have proven that the transformation of α-pyroxH₂ is copper(II)-assisted. By changing the solvent from MeOH to MeCN, the polymeric compound {[Cu₄Cl₄(pic)₄]}_n (2) was isolated; pic⁻ is the pyridine-2-carboxylato(-1) ligand. The observed α-pyroxH₂ → pic⁻ transformation is also copper(II)-assisted. The topology of the metal ions in 1 can be described as consisting of four consecutive isosceles triangles in a zigzag configuration. Complex 2 is a 2D coordination polymer consisting of Cu^II₄ squares. Complete mechanistic views for the α-pyroxH₂ → mpydol²⁻, pydox²⁻ and pic⁻ transformations are critically discussed. In 1, the six Cu^II ions of the “central” triangles seem to be strongly antiferromagnetically coupled, thus cancelling out their spins ($S_{{\mathrm{Cu}}_6}$ = 0). The two local spins of S = 1/2 for each of the antiferromagnetically coupled “terminal” Cu^II₃ triangles result in an overall S = 1 ground state spin value for 1. In 2, the four Cu^II ions within each tetrameric unit are practically isolated and ferromagnetic interactions occur between these units through Cu^II–(μ-Cl)–Cu^II bridges. Full article

Introduction: Inhibiting cyclooxygenase-2 (COX-2) is a potential strategy in inflammation therapy. Thus, developing COX-2 inhibitors plays a pivotal role in efficient inflammation treatment. This study discloses the synthesis of new heterocyclic compounds incorporating pyridine, pyran, and/or pyrazole moieties as COX-2 inhibitors. Methods: In this study, the Claisen–Schmidt reaction of 1-(5-hydroxy-1,3-diphenyl-1H-pyrazol-4-yl)ethan-1-one 1 and p-methoxybenzaldehyde in ethanol containing aqueous sodium hydroxide (10%) led to the formation of 1-(5-hydroxy-1,3-diphenyl-1H-pyrazol-4-yl)-3-(4-methoxyphenyl)prop-2-en-1-one) 2. The latter compound was allowed to react as a key precursor with various nucleophiles such as ethyl cyanoacetate, malononitrile, cyclohexanone, ethyl acetoacetate, hydrazine, cyano acid hydrazide, hydrazide, and/or thiosemicarbazide to yield new heterocyclic derivatives comprising pyridine, pyran, and/or pyrazole moieties 3–15, according to the Michael addition reaction. The newly synthesized compounds were depicted using spectroscopic techniques such as IR, ¹H-NMR, ¹³C-NMR, and MS. Moreover, their anti-inflammatory efficiency was in vitro evaluated by means of protein denaturation inhibition and cell membrane protection assay. Results: The results of 2^−ΔΔct values of COX-2 expression for compounds 6, 11, 12, and 13 were 6.6, 2.9, 25.8, and 10.1, respectively. Therefore, compound 12, followed by 13, 11, and 6, showed potent anti-inflammatory properties by in vitro evaluation. Further, an in silico molecular docking study was performed on the best-docked compounds and reference drug (Diclofenac) to investigate their binding affinities against the active site of the target enzyme. The obtained results from the in silico study aligned with the biological evaluation. Conclusions: The studies open new doors for designing new heterocycles containing pyridine, pyran, and/or pyrazole moieties as potent anti-inflammatory agents. Full article

Consumers prefer mung beans for their low allergenicity and nutritional benefits. However, flavour development in mung bean foods has been problematic, with beany flavour being a limiting factor. Hot processing is crucial in forming mung bean flavours, and storage-induced changes in flavour precursors directly impact the taste post-processing. This study used metabolomics to analyse the effects of hot processing (baking and cooking) on mung bean flavour and differences after storage. A total of 131 flavour precursors and 45 volatile substances were identified across six sample groups. The results showed that baking and cooking upregulated 22 and 18 volatile substances (ketones, aldehydes, esters, pyridine, pyrazines, etc.), respectively. The Maillard reaction during baking notably increased compounds like 2-hydroxypyridine, 2-methoxy-3-isobutyl pyrazine, 1,2-hexanedione, and 2,3-butanedione. Both methods inhibited linoleic acid oxidation, significantly reducing hexanal content, a key “bean” odour substance. However, storage accelerated linoleic acid conversion to C13 peroxides, increasing hexanal content and bean odour. This process decreased precursor substances like glucose-1-phosphate and caused the accumulation of pyruvic acid intermediates in pentose phosphate and pyruvate metabolism/amino acid metabolism pathways, leading to reduced mung bean taste richness. Full article

Heterobimetallic complexes of an ambidentate deferiprone derivative, 3-hydroxy-2-methyl-1-(3-((pyridin-2-ylmethyl)amino)propyl)pyridin-4(1H)-one (PyPropHpH), incorporating an octahedral [Co(4N)]³⁺ (4N = tris(2-aminoethyl)amine (tren) or tris(2-pyridylmethyl)amine (tpa)) and a half-sandwich type [(η⁶-p-cym)Ru]²⁺ (p-cym = p-cymene) entity have been synthesized and characterized by various analytical techniques. The reaction between PyPropHpH and [Co(4N)Cl]Cl₂ resulted in the exclusive (O,O) coordination of the ligand to Co(III) yielding [Co(tren)PyPropHp](PF₆)₂ (1) and [Co(tpa)PyPropHp](PF₆)₂ (2). This binding mode was further supported by the molecular structure of [Co(tpa)PyPropHp]₂(ClO₄)₃(OH)·6H₂O (5) and [Co(tren)PyPropHpH]Cl(PF₆)₂·2H₂O·C₂H₅OH (6), respectively, obtained via the slow evaporation of the appropriate reaction mixtures and analyzed using X-ray crystallography. Subsequent treatment of 1 or 2 with [Ru(η⁶-p-cym)Cl₂]₂ in a one-pot reaction afforded the corresponding heterobimetallic complexes, [Co(tren)PyPropHp(η⁶-p-cym)RuCl](PF₆)₃ (3) and [Co(tpa)PyPropHp(η⁶-p-cym)RuCl](PF₆)₃ (4), in which the piano-stool Ru core is coordinated by the (N,N) chelating set of the ligand. Cyclic voltammetric measurements revealed that the tpa complexes can be reduced at less negative potentials, suggesting their capability to be bioreductively activated under hypoxia (1% O₂). Hypoxia activation of 2 and 4 was demonstrated by cytotoxicity studies on the MCF-7 human breast cancer cell line. PyPropHpH was shown to be a typical iron-chelating anticancer agent, raising the mRNA levels of TfR1, Ndrg1 and p21. Further qRT-PCR studies provided unambiguous evidence for the bioreduction of 2 after 72 h incubation under hypoxia, in which the characteristic gene induction profile caused by the liberated iron-sequestering PyPropHpH was observed. Full article

Long-range proton transfer in several conjugated proton cranes, originating from 7-hydroxy quinoline as a proton transfer platform, has been investigated theoretically by means of DFT and TD-DFT methodology. Major emphasis was given to their applicability to provide clean switching upon irradiation. The border conditions require the existence of a single enol tautomer in the ground state, which under excitation through a series of consecutive exited and ground state intramolecular proton transfer steps is transferred to the keto tautomer. It was shown that the most suitable candidates are based on using iso-quinoline, pyrimidine and 4-nitropyridine as proton crane units. Their suitability is a function of aromaticity changes, the basicity of the nitrogen atom from the proton crane unit and the structural effects originating from their conjugation with 7-hydroxy quinoline. Full article

Monomers of N-hydroxypyridine-2(1H)-thione were isolated in low-temperature matrices of solid normal hydrogen (n-H₂). The matrix-isolated compound was irradiated with UV-B (λ = 305 nm) or UV-A (λ > 360 nm) light. Upon such irradiation, the initial form of N-hydroxypyridine-2(1H)-thione was completely consumed and converted into photoproducts. 2-Mercaptopyridine and water were identified as the main products of these photochemical transformations. Identification of photoproduced 2-mercaptopyridine is unquestionable. It is based on the identity of two sets of IR bands: (i) the bands observed in the IR spectrum recorded (in a separate experiment) for monomers of 2-mercaptopyridine trapped in an n-H₂ matrix and (ii) a set of IR bands observed in the spectrum recorded after UV irradiation of N-hydroxypyridine-2(1H)-thione. It should be emphasized that the UV-induced processes, occurring for N-hydroxypyridine-2(1H)-thione isolated in an n-H₂ matrix, lead to products that are significantly different from those generated from the compound trapped in solid Ar or in solid N₂. Full article

An efficient and operationally simple method for the synthesis of α-acyloxy ketones through the readily available 2-methylimidazole-promoted reaction of α-hydroxy ketones and anhydrides is developed. In the reaction, the anhydrides act as both a substrate and a solvent. The new method features good substrate tolerance, mild reaction conditions, readily accessible starting materials, and excellent yields, providing facile and green access to the targets. Importantly, the reaction also avoids the use of reagents with pungent odors, such as pyridine, in traditional esterification, which may promote the development of organocatalysis using nitrogen-containing heterocyclic compounds as catalysts. Full article

2-Chloropyridine-3-carbonitrile derivative 1 was utilized as a key precursor to build a series of linear and angular annulated pyridines linked to a 6-hydroxy-4,7-dimethoxybenzofuran moiety. Reaction of substrate 1 with various hydrazines afforded pyrazolo[3,4-b]pyridines. Treatment of substrate 1 with 1,3-N,N-binucleophiles including 3-amino-1,2,4-triazole, 5-amino-1H-tetrazole, 3-amino-6-methyl-1,2,4-triazin-5(4H)-one and 2-aminobenzimidazole produced the novel angular pyrido[3,2-e][1,2,4]triazolo[4,3-a]pyrimidine, pyrido[3,2-e][1,2,4]tetrazolo[1,5-a]pyrimidine, pyrido[3′,2′:5,6] pyrimido[2,1-c][1,2,4]triazine and benzo[4,5]imidazo[1,2-a]pyrido[3,2-e]pyrimidine, respectively. Reaction of substrate 1 with 1,3-C,N-binucleophiles including cyanoacetamides and 1H-benzimidazol-2-ylacetonitrile furnished 1,8-naphthyridines and benzoimidazonaphthyridine. Moreover, reacting substrate 1 with 5-aminopyrazoles gave pyrazolo[3,4-b][1,8]naphthyridines. Finally, reaction of compound 1 with 6-aminouracils as cyclic enamines yielded pyrimido[4,5-b][1,8]naphthyridines. Some of the synthesized products showed noteworthy antimicrobial efficiency against all types of microbial strains. Structures of the produced compounds were established using analytical and spectroscopic tools. Full article

The Caf1/CNOT7 nuclease is a catalytic component of the Ccr4-Not deadenylase complex, which is a key regulator of post-transcriptional gene regulation. In addition to providing catalytic activity, Caf1/CNOT7 and its paralogue Caf1/CNOT8 also contribute a structural function by mediating interactions between the large, non-catalytic subunit CNOT1, which forms the backbone of the Ccr4-Not complex and the second nuclease subunit Ccr4 (CNOT6/CNOT6L). To facilitate investigations into the role of Caf1/CNOT7 in gene regulation, we aimed to discover and develop non-nucleoside inhibitors of the enzyme. Here, we disclose that the tri-substituted 2-pyridone compound 5-(5-bromo-2-hydroxy-benzoyl)-1-(4-chloro-2-methoxy-5-methyl-phenyl)-2-oxo-pyridine-3-carbonitrile is an inhibitor of the Caf1/CNOT7 nuclease. Using a fluorescence-based nuclease assay, the activity of 16 structural analogues was determined, which predominantly explored substituents on the 1-phenyl group. While no compound with higher potency was identified among this set of structural analogues, the lowest potency was observed with the analogue lacking substituents on the 1-phenyl group. This indicates that substituents on the 1-phenyl group contribute significantly to binding. To identify possible binding modes of the inhibitors, molecular docking was carried out. This analysis suggested that the binding modes of the five most potent inhibitors may display similar conformations upon binding active site residues. Possible interactions include π-π interactions with His225, hydrogen bonding with the backbone of Phe43 and Van der Waals interactions with His225, Leu209, Leu112 and Leu115. Full article