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"Chen, Ye"
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Stereocontrolled 1,3-nitrogen migration to access chiral α-amino acids
α-Amino acids are essential for life as building blocks of proteins and components of diverse natural molecules. In both industry and academia, the incorporation of unnatural amino acids is often desirable for modulating chemical, physical and pharmaceutical properties. Here we report a protocol for the economical and practical synthesis of optically active α-amino acids based on an unprecedented stereocontrolled 1,3-nitrogen shift. Our method employs abundant and easily accessible carboxylic acids as starting materials, which are first connected to a nitrogenation reagent, followed by a highly regio- and enantioselective ruthenium- or iron-catalysed C(
sp
3
)–H amination. This straightforward method displays a very broad scope, providing rapid access to optically active α-amino acids with aryl, allyl, propargyl and alkyl side chains, and also permits stereocontrolled late-stage amination of carboxylic-acid-containing drugs and natural products.
A straightforward method for synthesizing optically active α-amino acids from abundant carboxylic acids has been developed. Based on a nitrene-mediated stereocontrolled 1,3-nitrogen shift, this approach provides access to a large variety of unnatural α-amino acids with aryl, allyl, propargyl and alkyl side chains and enables late-stage amination of carboxylic-acid-containing drugs.
Journal Article
The Signaling Pathways Regulating NLRP3 Inflammasome Activation
AbstractThe NLRP3 inflammasome is a multi-molecular complex that acts as a molecular platform to mediate caspase-1 activation, leading to IL-1β/IL-18 maturation and release in cells stimulated by various pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs). This inflammasome plays an important role in the innate immunity as its activation can further promote the occurrence of inflammation, enhance the ability of host to remove pathogens, and thus facilitate the repair of injured tissues. But if the inflammasome activation is dysregulated, it will cause the development of various inflammatory diseases and metabolic disorders. Therefore, under normal conditions, the activation of inflammasome is tightly regulated by various positive and negative signaling pathways to respond to the stimuli without damaging the host itself while maintaining homeostasis. In this review, we summarize recent advances in the major signaling pathways (including TLRs, MAPK, mTOR, autophagy, PKA, AMPK, and IFNR) that regulate NLRP3 inflammasome activation, providing a brief view of the molecular network that regulates this inflammasome as a theoretical basis for therapeutic intervention of NLRP3 dysregulation-related diseases.
Journal Article
Klotho overexpression improves amyloid‐β clearance and cognition in the APP/PS1 mouse model of Alzheimer's disease
Alzheimer's disease (AD) is the most prevalent type of dementia, characterized by the presence of amyloid‐β (Aβ) plaques. We previously reported that Klotho lowered Aβ levels in the brain and protected against cognitive deficits in amyloid precursor protein/presenilin 1(APP/PS1) mice. However, the underlying mechanism remains unclear. In this study, we induced intracerebral Klotho overexpression in 13‐month‐old APP/PS1 mice by injecting lentivirus that carried full‐length mouse Klotho cDNA in the lateral ventricle of the brain. We examined the effects of Klotho overexpression on cognition, Aβ burden, Aβ‐related neuropathology, microglia transformation, and Aβ transport systems in vivo. Additionally, we investigated the effects of Klotho on Aβ transport at the blood–cerebrospinal fluid barrier by knocking down Klotho in primary human choroid plexus epithelial cells (HCPEpiCs). The upregulation of Klotho levels in the brain and serum significantly ameliorated Aβ burden, neuronal and synaptic loss and cognitive deficits in aged APP/PS1 mice. Klotho treatment significantly inhibited NACHT, LRR, and PYD domain‐containing protein 3 (NLRP3) and the subsequent transformation of microglia to the M2 type that may enhance microglia‐mediated Aβ clearance. Meanwhile, Klotho overexpression also regulated Aβ transporter expression, which may promote Aβ transporter‐mediated Aβ clearance. Moreover, the ability of HCPEpiCs to transport Aβ in vitro was also significantly impaired by Klotho knockdown. Given the neuroprotective effect of Klotho overexpression, the present findings suggest that Klotho should be further investigated as a potential therapeutic target for AD.
Klotho, as an anti‐aging gene, has been studied in the field of AD in recent years. Our data showed that Klotho overexpression inhibited NLRP3 inflammasome activation and promoted Aβ clearance through an increase in M2 type microglia and the regulation of Aβ transporters in APP/PS1 mice, which effectively relieved neuroinflammation and Aβ burden and ameliorated AD‐like phenotypes.
Journal Article
Organic Photothermal Cocrystals: Rational Design, Controlled Synthesis, and Advanced Application
Organic photothermal cocrystals, integrating the advantages of intrinsic organic cocrystals and the fascinating photothermal conversion ability, hold attracted considerable interest in both basic science and practical applications, involving photoacoustic imaging, seawater desalination, and photothermal therapy, and so on. However, these organic photothermal cocrystals currently suffer individual cases discovered step by step, as well as the deep and systemic investigation in the corresponding photothermal conversion mechanisms is rarely carried out, suggesting a huge challenge for their further developments. Therefore, it is urgently necessary to investigate and explore the rational design and synthesis of high‐performance organic photothermal cocrystals for future applications. This review first and systematically summarizes the organic photothermal cocrystal in terms of molecular classification, the photothermal conversion mechanism, and their corresponding applications. The timely interpretation of the cocrystal photothermal effect will provide broad prospects for the purposeful fabrication of excellent organic photothermal cocrystals toward great efficiency, low cost, and multifunctionality.
Organic cocrystal simply self‐assembled from two or more different chemical species through noncovalent interactions has great superiority over monocomponent on their unpredicted and regulated chemicophysical properties, which provides a valuable guidance for the development of photothermal conversion. This minireview highlights the recent advances of organic photothermal cocrystals on the rational design, controlled synthesis, and advanced application.
Journal Article
Banana MaNAC1 activates secondary cell wall cellulose biosynthesis to enhance chilling resistance in fruit
Summary
Chilling injury has a negative impact on the quantity and quality of crops, especially subtropical and tropical plants. The plant cell wall is not only the main source of biomass production, but also the first barrier to various stresses. Therefore, improving the understanding of the alterations in cell wall architecture is of great significance for both biomass production and stress adaptation. Herein, we demonstrated that the cell wall principal component cellulose accumulated during chilling stress, which was caused by the activation of MaCESA proteins. The sequence‐multiple comparisons show that a cold‐inducible NAC transcriptional factor MaNAC1, a homologue of Secondary Wall NAC transcription factors, has high sequence similarity with Arabidopsis SND3. An increase in cell wall thickness and cellulosic glucan content was observed in MaNAC1‐overexpressing Arabidopsis lines, indicating that MaNAC1 participates in cellulose biosynthesis. Over‐expression of MaNAC1 in Arabidopsis mutant snd3 restored the defective secondary growth of thinner cell walls and increased cellulosic glucan content. Furthermore, the activation of MaCESA7 and MaCESA6B cellulose biosynthesis genes can be directly induced by MaNAC1 through binding to SNBE motifs within their promoters, leading to enhanced cellulose content during low‐temperature stress. Ultimately, tomato fruit showed greater cold resistance in MaNAC1 overexpression lines with thickened cell walls and increased cellulosic glucan content. Our findings revealed that MaNAC1 performs a vital role as a positive modulator in modulating cell wall cellulose metabolism within banana fruit under chilling stress.
Journal Article
Role of oxidative stress and inflammation-related signaling pathways in doxorubicin-induced cardiomyopathy
Doxorubicin (DOX) is a powerful and commonly used chemotherapeutic drug, used alone or in combination in a variety of cancers, while it has been found to cause serious cardiac side effects in clinical application. More and more researchers are trying to explore the molecular mechanisms of DOX-induced cardiomyopathy (DIC), in which oxidative stress and inflammation are considered to play a significant role. This review summarizes signaling pathways related to oxidative stress and inflammation in DIC and compounds that exert cardioprotective effects by acting on relevant signaling pathways, including the role of Nrf2/Keap1/ARE, Sirt1/p66Shc, Sirt1/PPAR/PGC-1α signaling pathways and NOS, NOX, Fe
2+
signaling in oxidative stress, as well as the role of NLRP3/caspase-1/GSDMD, HMGB1/TLR4/MAPKs/NF-κB, mTOR/TFEB/NF-κB pathways in DOX-induced inflammation. Hence, we attempt to explain the mechanisms of DIC in terms of oxidative stress and inflammation, and to provide a theoretical basis or new idea for further drug research on reducing DIC.
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Video Abstract
Journal Article
Dual catalysis for enantioselective convergent synthesis of enantiopure vicinal amino alcohols
Enantiopure vicinal amino alcohols and derivatives are essential structural motifs in natural products and pharmaceutically active molecules, and serve as main chiral sources in asymmetric synthesis. Currently known asymmetric catalytic protocols for this class of compounds are still rare and often suffer from limited scope of substrates, relatively low regio- or stereoselectivities, thus prompting the development of more effective methodologies. Herein we report a dual catalytic strategy for the convergent enantioselective synthesis of vicinal amino alcohols. The method features a radical-type Zimmerman–Traxler transition state formed from a rare earth metal with a nitrone and an aromatic ketyl radical in the presence of chiral
N
,
N
′-dioxide ligands. In addition to high level of enantio- and diastereoselectivities, our synthetic protocol affords advantages of simple operation, mild conditions, high-yielding, and a broad scope of substrates. Furthermore, this protocol has been successfully applied to the concise synthesis of pharmaceutically valuable compounds (e.g., ephedrine and selegiline).
Chiral vicinal amino alcohols are found in many bioactive compounds and may serve as chiral ligands. Here, the authors report a photocatalytic enantioselective cross-coupling of nitrones with aromatic aldehydes with a chiral ligand-coordinated rare earth ion synergistically producing enantiopure vicinal amino alcohols.
Journal Article
2022 Chinese national clinical practice guideline on Helicobacter pylori eradication treatment
Helicobacter pylori ( H. pylori ) infection is an infectious disease with a prevalence rate of up to 50% worldwide. It can cause indigestion, gastritis, peptic ulcer, and gastric cancer. H. pylori eradication treatment can effectively control disease progression and reduce the risk of the above conditions. However, the escalating trend of antibiotic resistance presents a global challenge for H. pylori eradication. We aim to provide guidance on pharmacological treatment of H. pylori infection.
This clinical practice guideline is developed following the World Health Organization's recommended process, adopting Grading of Recommendations Assessment, Development and Evaluation in assessing evidence quality, and utilizing Evidence to Decision framework to formulate clinical recommendations, minimizing bias and increasing transparency of the clinical practice guideline development process. We used the Reporting Items for practice Guidelines in HealThcare (RIGHT) statement and The Appraisal of Guidelines for Research and Evaluation II (AGREE II) as reporting and conduct guides to ensure the guideline's completeness and transparency.
Though decreasing in developed countries, the prevalence of H. pylori remains high in developing countries, causing a major public health burden. This clinical practice guideline contains 12 recommendations concerning pharmacological treatment for H. pylori eradication. Among them, it is worth highlighting that bismuth preparations are inexpensive, safe, and effective, consequently making bismuth quadruple therapy a preferred choice for initial and rescue treatment. In empirical treatment, high-dose dual therapy is equally effective compared with bismuth quadruple therapy.
The 12 recommendations in this clinical practice guideline are formed with consideration for stakeholders' values and preferences, resource use, feasibility, and acceptability. Recommendations are generalizable to resource limited settings with similar antibiotic resistance pattern as China, and lower middle-income countries facing comparable sociological and technical challenges.
Guidelines International Network (GIN) website, https://guidelines.ebmportal.com/node/69996 .
Journal Article