The development of chiroptical molecular switches for chiral sensing, data communication, optical displays, chiral logic gates, and asymmetric catalysis is currently a vibrant frontier of science and technology. Herein, we report a practical artificial dynamic system based on a 1,2-diaxial atropisomer. Organocatalytic parallel kinetic resolution allows the divergent synthesis of two sets of stereoisomers with vicinal C-C and N-N axes from the same racemic single-axis substrates.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
While biological machines are powered mainly by chemical transformations, chemically driven artificial rotary motor systems are very limited. Here, we report an aniline-phenol-based rotary molecular motor that operates via an information ratchet mechanism. The 360° directional rotation about a single covalent bond can be chemically driven by reversible oxazepine formation.
View Article and Find Full Text PDFSarcoplasmic calcium-binding protein (Cra a 4) from belongs to the EF-hand superfamily, and understanding of its structure-allergenicity relationship is still insufficient. In this study, chemical denaturants were used to destroy the structure of Cra a 4, showing that disruption of the structure reduced its IgG-/IgE-binding activity. To explore which critical amino acid site affects the allergenicity of Cra a 4, the mutants were obtained by site-directed mutations in the disulfide bonds site (C), conformational epitopes (I, D), or Ca-binding region (D, D) and their IgG-/IgE-binding activity was reduced significantly using serological tests.
View Article and Find Full Text PDFReported herein is a highly efficient dynamic kinetic resolution protocol for the atroposelective synthesis of heterobiaryls with vicinal C-C and N-N diaxes. Atropisomers bearing vicinal diaxes mainly exist in -triaryls, while that of biaryls is highly challenging in terms of the concerted rotation and deplanarization effects. The combination of C-C biaryl with N-N nonbiaryl delivers a novel class of vicinal-diaxis heterobiaryls.
View Article and Find Full Text PDFThe catalytic asymmetric dearomatization (CADA) reaction has proved to be a powerful protocol for rapid assembly of valuable three-dimensional cyclic compounds from readily available planar aromatics. In contrast to the well-studied indoles and naphthols, phenols have been considered challenging substrates for intermolecular CADA reactions due to the combination of strong aromaticity and potential regioselectivity issue over the multiple nucleophilic sites (O, C2 as well as C4). Reported herein are the chiral phosphoric acid-catalyzed divergent intermolecular CADA reactions of common phenols with azoalkenes, which deliver the tetrahydroindolone and cyclohexadienone products bearing an all-carbon quaternary stereogenic center in good yields with excellent ee values.
View Article and Find Full Text PDFThe first catalytic asymmetric interrupted Attanasi reaction has been established. Under the catalysis of a bifunctional organocatalyst, the condensation of cyclic β-keto esters with azoalkenes readily occurred, delivering a variety of bicyclic fused 2,3-dihydropyrroles with vicinal quaternary stereogenic centers in good yields and with good to excellent enantioselectivities (27 examples, up to 96% yield and 95% ee).
View Article and Find Full Text PDFThe Sc(III)-catalyzed [2,3]-sigmatropic rearrangement of sulfonium ylides derived from azoalkenes has been established. Owing to the absence of a carbenoid intermediate, this protocol represents the first non-carbenoid variant of the Doyle-Kirmse reaction. Under mild conditions, a variety of tertiary thioethers have been readily prepared in good to excellent yields.
View Article and Find Full Text PDFArginine kinase (AK) was identified as an allergen in . However, little information is available about its epitopes. In this study, AK from was registered to the World Health Organization/International Union of Immunological Societies allergen nomenclature committee to be named as Cra a 2.
View Article and Find Full Text PDFAxially chiral biaryl diols have achieved great success in asymmetric catalysis. By contrast, axially chiral biaryl amino alcohols are far less developed. Herein, we have rationally designed a versatile C -symmetric biaryl amino alcohol scaffold 1-(1-amino-pyrrol-2-yl)naphthalen-2-ol (NPNOL) on the basis of axially chiral C2-arylpyrrole framework.
View Article and Find Full Text PDF-Unsaturated -ketoesters prove to be versatile organic synthons participating in diverse catalytic asymmetric transformations with the breathtaking development of organo-catalysis, new catalytic systems including ingenious chiral ligands as well as Lewis acid cations. The highly efficient creation of stereogenic centers with excellent enantioselectivity is not a surprise, but owes to the bidentate coordination of its unique 1,2-dicarbonyl motif to artful chiral messenger, establishing a rigid system for the precise chiral-identification of the attack. In the past five years, various reaction modes of -unsaturated -ketoesters have been developed, involving their multiple reaction sites, such as the carbon-carbon double bond (C=C), the carbonyl group (C=O), the entire C=C-C=O fragment, and the ester group.
View Article and Find Full Text PDFOyster is a common food that causes allergy. However, little information is available about its allergens and cross-reactivity. In this study, arginine kinase (AK) was identified as a novel allergen in .
View Article and Find Full Text PDFChem Commun (Camb)
September 2021
The first Brønsted acid-catalyzed oxa-Michael reaction cascade of 2-indolylmethanols with trione alkenes was accomplished. By using this practical approach, a variety of tetracyclic indoles were readily created in an ordered sequence with excellent regio- and diastereoselectivity. 2-Indolylmethanols commendably served as four-atom synthons, as opposed to the common three-atom synthons in the previous literature reports.
View Article and Find Full Text PDFSarcoplasmic-calcium-binding protein (SCP) has been investigated as a novel allergen in . Nevertheless, knowledge of its effector-cell-based allergic relevance and epitopes is limited. In this study, the heat-resistant allergen SCP was able to induce significant upregulation of CD63 and CD203c ( < 0.
View Article and Find Full Text PDFAllergic reactions occur after the whole food is ingested, rather than the purified allergen. The present study explores the low-allergenic food processing for by analysis of macrostructure, digestibility, and immunoreactivity. Furthermore, the presence of modified amino acids on the reported IgE epitopes was analyzed by mass spectrometry.
View Article and Find Full Text PDFFood processing can change the structure and immunoreactivity of purified allergens, but the effect of food processing on the immunoreactivity of the processed and purified allergen is still poorly understood. In this study, tropomyosin (TM) was obtained from Scylla paramamosain and purified after different treatments. A basophil activation test was employed to detect the allergenicity of allergens.
View Article and Find Full Text PDFOysters are an important shellfish group known to cause food allergy; however, knowledge of their sensitization components and cross-reactivity is limited. This study aimed to identify a novel allergen in and investigate its cross-reactivity. To this end, a 20 kDa protein was purified from oyster and confirmed to be a sarcoplasmic-calcium-binding protein (SCP) by LC-MS/MS.
View Article and Find Full Text PDFMany types of shellfish, including shrimp, are sometimes cooked before ingestion. Hence, it is necessary to investigate how cooking (boiling, pressure treatment or none (raw)) affects the structure, digestibility and immunoreactivity of multi-component shrimp muscle. Protein extraction, simulated gastrointestinal digestion, immunoreactivity, immunoglobulin E (IgE)-mediated human mast cell degranulation, morphology, particle size and UV absorbance scanning were used to investigate changes in the shrimp muscle upon treatment.
View Article and Find Full Text PDFA series of flavone-7-phosphoramidate derivatives were synthesized and tested for their antiproliferative activity in vitro against human hepatoma cell line HepG2 and human normal hepatic cell line L-O2. Compound 8d, 16d and 17d, incorporating the amino acid alanine, exhibited high inhibitory activity on HepG2 cell line with IC50 values of 9.0 μmol/L, 5.
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