Alzheimer's disease (AD) is the most common type of neurodegenerative disease in the contemporary era, and it is still clinically incurable. Eriodictyol, a natural flavonoid compound that is mainly ...present in citrus fruits and some Chinese herbal medicines, has been reported to exert anti-inflammatory, antioxidant, anticancer and neuroprotective effects. However, few studies have examined the anti-AD effect and molecular mechanism of eriodictyol.
APP/PS1 mice were treated with eriodictyol and the cognitive function of mice was assessed using behavioral tests. The level of amyloid-β (Aβ) aggregation and hyperphosphorylation of Tau in the mouse brain were detected by preforming a histological analysis and Western blotting. HT-22 cells induced by amyloid-β peptide (1-42) (Aβ
) oligomers were treated with eriodictyol, after which cell viability was determined and the production of p-Tau was tested using Western blotting. Then, the characteristics of ferroptosis, including iron aggregation, lipid peroxidation and the expression of glutathione peroxidase type 4 (GPX4), were determined both in vivo and in vitro using Fe straining, Western blotting and qPCR assays. Additionally, the expression level of vitamin D receptor (VDR) and the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway were tested using Western blotting and qPCR assays. Afterward, HT-22 cells with VDR knockout were used to explore the potential mechanisms, and the relationship between VDR and Nrf2 was further assessed by performing a coimmunoprecipitation assay and bioinformatics analysis.
Eriodictyol obviously ameliorated cognitive deficits in APP/PS1 mice, and suppressed Aβ aggregation and Tau phosphorylation in the brains of APP/PS1 mice. Moreover, eriodictyol inhibited Tau hyperphosphorylation and neurotoxicity in HT-22 cells induced by Aβ
oligomer. Furthermore, eriodictyol exerted an antiferroptosis effect both in vivo and in vitro, and its mechanism may be associated with the activation of the Nrf2/HO-1 signaling pathway. Additionally, further experiments explained that the activation of Nrf2/HO-1 signaling pathway by eriodictyol treatment mediated by VDR.
Eriodictyol alleviated memory impairment and AD-like pathological changes by activating the Nrf2/HO-1 signaling pathway through a mechanism mediated by VDR, which provides a new possibility for the treatment of AD.
The development of productive catalysts for the oxygen evolution reaction (OER) remains a major challenge requiring significant progress in both mechanism and material design. Conventionally, the ...thermodynamic barrier of lattice oxidation mechanism (LOM) is lower than that of absorbate evolution mechanism (AEM) because the former can overcome certain limitations. However, controlling the OER pathway from the AEM to the LOM by exploiting the intrinsic properties of the catalyst remains challenging. Herein, we incorporated F anions into the oxygen vacancies of spinel ZnCo2O4 and established a link between the electronic structure and the OER catalytic mechanism. Theoretical density calculations revealed that F upshifts the O 2p center and activates the redox capability of lattice O, successfully triggering the LOM pathway. Moreover, the high electronegativity of F anions is favourable for balancing the residual protonation, which can stabilize the structure of the catalyst.
In this work, we successfully filled the lattice oxygen vacancies of ZnCo2O4 with F atom, achieving the activation of lattice oxygen by regulating metal‐oxygen hybridization, and the dominant oxygen evolution reaction mechanism on ZnCo2O4 can transform from adsorbate evolution mechanism to lattice oxygen oxidation mechanism.
Given a hyperelliptic curve C of genus g over a number field K and a Weierstrass model \mathscr {C} of C over the ring of integers \mathcal {O}_K ( i.e. the hyperelliptic involution of C extends to ...\mathscr {C} and the quotient is a smooth model of \mathbb {P}^1_K over \mathcal {O}_K), we give necessary and sometimes sufficient conditions for \mathscr {C} to be defined by a global Weierstrass equation. In particular, if C has everywhere good reduction, we prove that it is defined by a global integral Weierstrass equation with invertible discriminant if the class number h_K is prime to 2(2g+1), confirming a conjecture of M. Sadek.
Constructing rich defect active site structure for material design is still a great challenge. Herein, a simple surface engineering strategy is demonstrated to construct one‐unit‐cell ZnIn2S4 atomic ...layers with the modulated surface energy of S vacancy. Rich surface energy can regulate and control the rich S vacancy, which ensures rich active sites, higher charge density and effective carrier transport. As a result, the ZnIn2S4 atomic layers with rich surface energy affords an obvious enhancement in H2O2 productive rate of 1592.04 µmol g−1 h−1, roughly 14.58 times superior to that with poor surface energy. Moreover, the in situ infrared diffuse reflection spectrum indicates that S vacancy as the oxygen reduction reaction active site is responsible for the critical intermediate *O2− and *OOH, corresponding to two‐electron oxygen reduction reaction. This study provides a valuable insight and guidance for constructing controllably defects to achieve highly efficient H2O2 production.
The ZnIn2S4 atomic layer with rich defect active sits is designed and prepared by a simple hydrothermal method. The relationship between surface energy and defects is investigated by density functional theory calculation and experiment, indicating that the controllable defects can be constructed by tuning surface energy. As the rich active site, S defect played a very important role in charge density and effective carrier transport during the photocatalytic H2O2 production.
Fluorinated ketones are widely prevalent in numerous biologically interesting molecules, and the development of novel transformations to access these structures is an important task in organic ...synthesis. Herein, we report the multicomponent radical acylfluoroalkylation of a variety of olefins in the presence of various commercially available aromatic aldehydes and fluoroalkyl reagents through N‐heterocyclic carbene organocatalysis. With this protocol, over 120 examples of functionalized ketones with diverse fluorine substituents have been synthesized in up to 99 % yield with complete regioselectivity. The generality of this catalytic strategy was further highlighted by its successful application in the late‐stage functionalization of pharmaceutical skeletons. Excellent diastereoselectivity could be achieved in the reactions forging multiple stereocenters. In addition, preliminary results have been achieved on the catalytic asymmetric variant of the olefin difunctionalization process.
Organocatalytic acylfluoroalkylation: A multicomponent radical acylfluoroalkylation of olefins through NHC organocatalysis was developed, and over 120 examples of fluoroketones were facilely accessed from simple materials. Moreover, a dearomative difunctionalization of indoles could be readily achieved in a highly diastereoselective manner. The generality and practicality were highlighted by the late‐stage modification of drug skeletons.
The catalytic conversion of alcohols under mild conditions is a great challenge because it is constrained by low selectivity and low activity. Herein, we demonstrate a hollow nanotube Fe2O3/MoO3 ...heterojunction (FeMo‐2) for the photoelectrocatalytic conversion of small‐molecule alcohols. Experimental and theoretical analyses reveal that the optical carrier transfer rate is enhanced by constructing interfacial internal electric fields and Fe‐O‐Mo charge transfer channels. For the formox process, heterojunctions possess superior HCHO‐selective reaction paths and free energy transitions, optimizing the selectivity of HCHO and enhancing the reactivity. FeMo‐2 shows a greatly improved performance compared to single Fe2O3; the photocurrent density of FeMo‐2 reaches 0.66 mA cm−2, which is 3.88 times that of Fe2O3 (0.17 mA cm−2), and the Faraday efficiency of the CH3OH‐to‐HCHO conversion is 95.7 %. This work may deepen our understanding of interfacial charge separation and has potential for the production of HCHO and for conversion reactions of other small‐molecule alcohols at cryogenic temperatures.
A Z‐Scheme Fe2O3/MoO3 hollow nanotube with a CH3OH‐to‐HCHO selectivity of 95.7 % was developed. The thin‐walled hollow structure facilitates a fast transfer of photogenerated carriers and enhances light utilization. The Fe‐O‐Mo charge transfer channel and internal electric field in the Fe2O3/MoO3 interface improve the charge transfer efficiency. PEC experiments and calculations demonstrate that C−H bond breaking is the rate‐determining step.
Nitrogen heterocycles are important structural subunits that occur widely in bioactive natural products, pharmaceuticals, agrochemicals, dyes, cosmetics, and functional materials. Considering the ...importance of these useful compounds in modern science, the synthesis of N‐heterocycles and their derivatives has always been a hot topic in organic synthesis. Recently, arenediazonium salts which can be easily prepared from inexpensive and abundantly available anilines, have been used as versatile nitrogen sources in the field of nitrogen heterocycle synthetic chemistry due to their ready availability, rich reactivity, and diverse transformations. The aim of the present review is to summarize the recent advances in the synthesis of nitrogen heterocycles using arenediazonium salts as nitrogen sources in the past ten years. Hopefully, it can provide practical guidance for the readers who are interested in utilizing arenediazonium salts as building blocks in organic synthesis. For simplicity and clarity, the organization of this review is based on the number of N atoms in the ring of nitrogen heterocycle.
By using the more electro‐negative Mn3+ ion to partially replace Co3+ at the octahedral site of spinel ZnCo2O4, i.e., forming ternary Zn–Mn–Co spinel oxide, the electrocatalytic oxygen ...reduction/evolution activity is found to be significantly increased. Considering the physical characterization and theoretical calculations, it demonstrated that the bond competition played a key role in regulating the cobalt valence state and the electrocatalytic activity. The partial replacement of octahedral‐site‐occupied Co3+ by Mn3+ can effectively modulate the adjacent Co–O bond and induce the Jahn–Teller effect, thus changing the originally stable crystal structure and optimizing the binding strength between the active center and reaction intermediates. Certainly, the Mn‐substituted ZnMn1.4Co0.6O4/NCNTs exhibit higher electrocatalytic oxygen reduction reaction (ORR) activity than that of ZnCo2O4/NCNTs and ZnMn2O4/NCNTs, supporting that the Co–O bond covalency determines the ORR activity of spinel ZnCo2O4. This study offers the competition between adjacent Co–O and Mn–O bonds via the BOh–O–BOh edge‐sharing geometry. The ion substitution at octahedral sites by less electronegative cations can be a new and effective way to improve the electrocatalytic performance of cobalt‐based spinel oxides.
The excellent electrocatalytic performance of ZnMn1.4Co0.6O4/NCNTs for oxygen reduction reaction is verified, presenting significant power density and durability in Zn–air batteries. A bond competition mechanism for the octahedral sites of spinel is also proposed. The presence of bond competition between CoO and MnO enables to modulate and optimize the electronic structure of ZnMn1.4Co0.6O4, resulting in the superior electrocatalytic activity.
The efficacy and synthetic versatility of asymmetric organocatalysis have contributed enormously to the field of organic synthesis since the early 2000s. As asymmetric organocatalytic methods mature, ...they have extended beyond the academia and undergone scale-up for the production of chiral drugs, natural products, and enantiomerically enriched bioactive molecules. This review provides a comprehensive overview of the applications of asymmetric organocatalysis in medicinal chemistry. A general picture of asymmetric organocatalytic strategies in medicinal chemistry is firstly presented, and the specific applications of these strategies in pharmaceutical synthesis are systematically described, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial, and antiparasitic agents, as well as several miscellaneous bioactive agents. The review concludes with a discussion of the challenges, limitations and future prospects for organocatalytic asymmetric synthesis of medicinally valuable compounds.
This review provides a comprehensive overview of the recent applications of organocatalytic strategies in pharmaceutical synthesis, with a focus on the preparation of antiviral, anticancer, neuroprotective, cardiovascular, antibacterial and antiparasitic agents.
In response to the threat of COVID-19, China initiated a nationwide campaign. Ideological work such as explaining the implemented policies and persuading the public always took a central role in ...mobilization, and it has been emphasized by Chinese government during Covid-19 as well. The legitimation discourse used in the campaign is the focus of the current study. The investigation takes into consideration the political logic of the relationship between the central and local governments as well as their working mechanism. More specifically, a total of 84 open letters written by the local governments to mobilize residents during the COVID-19 pandemic were analyzed. The study integrated the CDA perspective, legitimation theory, and campaign-style governance and examined what ideological discourses are constructed in the open letters, what type of authority is constructed for legitimation, and what is the main communication style used. In addition, the study paid attention to the patterns among the different local government ranks. The findings revealed that moral appeal and political authority were the key elements of legitimation discourse, but governments with lower ranks exhibited a trend of de-ideologization. Meanwhile, impersonal politeness and direct bold command contradictorily co-existed in open letters of basic level local governments. These finding reveal that despite the top government’s centralized power, realization of ideological work in a national campaign is confined by the divergent and complicated realities of local governments.
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