Highly enantioselective 3+3 and 3+4 annulations of isatin‐derived enals with ethynylethylene carbonates and ethynyl benzoxazinanones are enabled by NHC/cooper cooperative catalysis, leading to a big ...library of spirooxindole derivatives in high structural diversity and enantioselectivity (up to 99 % ee). Both reactions represent a nicely synergistic integration of NHC and copper catalysis, in which both catalysts activate the substrates and the chiral NHC perfectly controls the stereochemistry.
All together now: A cooperative N‐heterocyclic carbene (NHC)/cooper catalytic system was developed for the diversity‐oriented synthesis of spirooxindole derivatives through enantioselective 3+3 and 3+4 annulation reactions. Highly enantioselective 3+3 and 3+4 annulations of isatin‐derived enals with ethynylethylene carbonates and ethynyl benzoxazinanones were achieved.
A hybrid palladium catalyst assembled from a chiral phosphoric acid (CPA) and thioamide enables a highly efficient and enantioselective β‐C(sp3)−H functionalization of thioamides (up to 99 % yield, ...97 % ee). A kinetic resolution of unsymmetrical thioamides by intermolecular C(sp3)−H arylation can be achieved with high s‐factors. Mechanistic investigations have revealed that stereocontrol is achieved by embedding the substrate in a robust chiral cavity defined by the bulky CPA and a neutral thioamide ligand.
Bulk up: A Pd‐catalyzed enantioselective β‐C(sp3)−H functionalization of thioamides has been developed using a chiral phosphoric acid (CPA) as the chiral auxiliary. Mass spectrometry studies and DFT analysis elucidate the role of the bulky CPA and the assistance of the thioamide ligand, which define a robust chiral cavity for achieving a high level of stereocontrol.
Nanoassemblies based on self‐assembly of biological building blocks are promising in mimicking the nanostructures, properties, and functionalities of natural enzymes. However, it remains a challenge ...to design of biomimetic nanozymes with tunable nanostructures and enhanced catalytic activities starting from simple biomolecules. Herein, the construction of nanoassemblies through coassembly of an amphiphilic amino acid and hemin is reported. The nanostructures and morphologies of the resulting nanoassemblies are readily controlled by tuning the molar ratio between the amino acid and hemin, thus leading to tailored peroxidase‐mimicking activities of the nanoassemblies. Importantly, the optimized nanoassemblies exhibit a remarkable catalytic efficiency that is comparable to the natural counterpart when considering molecular mass along with good robustness in multiple catalytic cycles. The nanoassemblies are effectively integrated as biomimetic nanozymes in a sensing system for catalytic detection of glucose. Therefore, this work demonstrates that nanozymes with advanced catalytic capabilities can be constructed by self‐assembly of minimalist biological building blocks and may thus promote the rational design and catalytic applications of biomimetic nanozymes.
Simple but complex: Biomimetic nanozymes with adjustable nanostructures, morphologies, and catalytic performances are facilely constructed by coassembly of minimalist biological building blocks, an amino acid derivative and hemin. The nanozymes exhibit a remarkable catalytic efficiency comparable to the natural horseradish peroxidase and show typical enzyme‐like characteristics in catalytic sensing of glucose.
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•MCP ameliorates ISO-induced myocardial fibrosis and cardiac dysfunction.•MCP decreases ISO-induced IL-1β, IL-18, TNF-α and Gal-3 levels.•MCP ameliorates myocardial fibrosis via ...inhibiting TLR4/MyD88/NF-κB signaling.
Myocardial fibrosis (MF) plays a key role in the development and progression of heart failure (HF) with limited effective therapies. Galectin-3 (Gal-3) is a biomarker associated with fibrosis and inflammation in patients with HF. The Gal-3 inhibitor modified citrus pectin (MCP) protects against cardiac dysfunction, though the underlying mechanism remains unclear. The aim of this study was to investigate the effect and mechanism of MCP on MF using an isoproterenol (ISO)-induced rat model of HF. Cardiac function was analyzed by echocardiography and electrocardiography. Histopathological changes in the heart tissue were assessed by hematoxylin-eosin and Masson trichrome staining. The mRNA and protein expression levels of signaling molecules and pro-inflammatory cytokines were monitored by immunohistochemistry, western blot, qRT-PCR and ELISA analyses. The results demonstrated that MCP ameliorated cardiac dysfunction, decreased myocardial injury and reduced collagen deposition. Furthermore, MCP downregulated the expression of Gal-3, TLR4 and MyD88, thereby inhibiting NF-κB-p65 activation. MCP also decreased the expression of IL-1β, IL-18 and TNF-α, which have been implicated in the pathogenesis of HF. These inhibitory effects were observed on day 15 and continued until day 22. Taken together, these results suggest that MCP ameliorates cardiac dysfunction through inhibiting inflammation and MF. These effects may be through downregulating Gal-3 expression and suppressing activation of the TLR4/MyD88/NF-κB signaling pathway. The present study supports the use of Gal-3 as a therapeutic target for the treatment of MF after myocardial infarction.
The first catalytic asymmetric decarboxylative 3 + 2 cycloaddition reaction of ethynylethylene carbonates with malononitrile has been developed successfully by an organo/copper cooperative system. ...This strategy led to a series of optically active polysubstituted dihydrofurans in good yields with high levels of enantioselectivities (up to 99% yield, 97% ee). The presence of the terminal alkynyl and the cyano group in the dihydrofuran products provides a wide scope for further structural transformations. More importantly, this organo/metal cooperative catalytic system will broaden the substrate scope and enable fundamentally new reactions.
Using Monte Carlo simulation, we investigated magnetic and thermodynamic characteristics of the rectangle core–shell ferrimagnetic mixed-spin (3/2, 2) Ising nanoribbon under the effects of sublattice ...crystal field, exchange coupling and temperature. Typical temperature dependence of the total magnetization, the core and shell magnetization, the susceptibility and the internal energy for several fixed values of Hamiltonian parameters were discussed in detail. The phase diagrams of the critical and compensation temperatures were presented in various Hamiltonian parameter planes. In addition, particular emphasis was given to the interesting multi-cycle hysteresis behaviors of the total system and sublattices. Our results show reasonable consistency compared with many previous theoretical and experimental studies.
•A rectangle core-shell ferrimagnetic Ising nanoribbon was proposed.•The effects of crystal field and exchange coupling were studied.•Magnetization, susceptibility and internal energy were discussed.•The phase diagrams of the critical and compensation temperatures were presented.•Interesting multi-cycle hysteresis behaviors were found.
Sirt6 has been implicated as a key regulator in aging-related diseases, including osteoarthritis. However, its functional role and molecular mechanism in chondrocyte senescence and osteoarthritis ...pathophysiology remain largely undefined. Here we show that Sirt6 deficiency exaggerates chondrocyte senescence and osteoarthritis progression, whereas intra-articular injection of adenovirus-Sirt6 markedly attenuates surgical destabilization of medial meniscus-induced osteoarthritis. Mechanistically, Sirt6 can directly interact with STAT5 and deacetylate STAT5, thus inhibiting the IL-15/JAK3-induced STAT5 translocation from cytoplasm to nucleus, which inactivates IL-15/JAK3/STAT5 signaling. Mass spectrometry revealed that Sirt6 deacetylated conserved lysine 163 on STAT5. Mutation of lysine 163 to arginine in STAT5 abolished the regulatory effect of Sirt6. In vivo, specific ablation of Sirt6 in chondrocytes exacerbated osteoarthritis. Pharmacological activation of Sirt6 substantially alleviated chondrocyte senescence. Taken together, Sirt6 attenuates chondrocyte senescence by inhibiting IL-15/JAK3/STAT5 signaling. Targeting Sirt6 represents a promising new approach for osteoarthritis.
African swine fever virus (ASFV) causes a highly contagious and often lethal swine viral disease, and leads to tremendous economic losses to the swine industry. Unfortunately, there are no vaccines ...and effective antiviral agents available to prevent and control ASFV outbreaks. Therefore, it is necessary to develop simple and rapid strategies to monitor ASFV-infected pigs to restrain its spread. In the current study, ASFV capsid protein p72 was expressed along with its chaperone pB602L to form trimers in human embryonic kidney 293 (HEK293) cells. The p72 trimers were subsequently labeled with colloidal gold to develop a immunochromatographic strip. The strip showed high specificity to ASFV-positive serum and no cross-reactivity to other swine virus positive sera. Importantly, the strip showed a higher sensitivity of detecting ASFV antibodies in both positive standard serum and clinical serum samples than a commercial enzyme-linked immunosorbent assay (ELISA) kit. Taken together, these results demonstrate the strip as a reliable diagnostic tool against ASFV infection, which will be appropriate for application in prevention and control of ASFV.
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ASFV p72 trimers were successfully generated
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A colloidal gold strip was developed based on ASFV p72 trimers
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The strip is appropriate for detecting ASFV antibodies in the field
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A mixed-spin (5/2, 3/2) Ising model is established to describe the antiferroelectric/ferroelectric (AFE/FE) BiFeO3/Co bilayer structure. We study the effects of the crystal field, exchange coupling ...and external longitudinal electric field on the dielectric properties of the bilayer based on Monte Carlo simulation. We illustrate the temperature dependence of polarization, susceptibility, internal energy and specific heat of the system in detail. As well, we depict the phase diagram and point out the rule of the blocking temperature with various parameters. In particular, we find rich and interesting multi-cycle electric hysteresis behaviors. The results show that these parameters play a crucial part in the physical properties of the AFE/FE BiFeO3/Co bilayer structure.
Asymmetric annulation of bench-stable α,β-unsaturated aryl esters with enamines was realized via cooperative catalysis of chiral isothiourea and Brønsted acid. This reaction proceeds via a chiral ...α,β-unsaturated acyl ammonium intermediate and offers a rapid access to functionalized 3,4-dihydropyridin-2-ones in high yields and excellent enantioselectivities.
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![Enantioselective [3 + 2] Cy...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1523-7060/small "Enantioselective [3 + 2] Cycloaddition Reaction of Ethynylethylene Carbonates with Malononitrile Enabled by Organo/Metal Cooperative Catalysis")
