Latest ArticlesTo overcome the shortcomings of single component carrier supported platinum (Pt)-based catalysts, herein, we demonstrate the fabrication of alumina combined mesoporous carbon to prepare a series of alumina-carbon composites and their corresponding Pt-based catalysts. The alumina-carbon composites Al@PhFC are synthesized by using phloroglucinol-formaldehyde resin as carbon source and aluminum acetylacetone as the aluminum source. Further, the effect of alumina content on the properties of the composites is investigated. The composites and catalysts are characterized by using XRD, XPS, N2 sorption, and TEM. The Pt/Al@PhFC-1.8 composite with appropriate amounts of alumina, pore diameter, and moderate Pt nanoparticle size, resulted in 99.5% of conversion efficiency and 77.4% of optical selectivity in the asymmetric hydrogenation of ethyl 2-oxo-4-phenylbutanoate (EOPB). Interestingly, this composite can be used more than 20 times without a significant decrease in its performance.
Dipyrrolyldiketone difluoroboron complexes (BONEPYs) were synthesized by condensation of the corresponding pyrroles and malonyl chloride followed by treatment with BF3·OEt2. The aryl-substituted pyrrole is introduced to form a cyclic system in order to investigate anion binding studies. In BONEPYs 1-3 the o-H of the aryl group forms hydrogen bonding with F- to give a more table complex. In contrast, the intramolecular hydrogen-bonded BONEPYendo-4 is more stable than its exo isomer. While adding F-, the hydrogen bonds must be broken first to give 4·(3)F-. Owing to the electron-rich group (-OMe), the o-H of the phenyl group can hardly interact with F- via hydrogen bonding to give the less stable complex 4·(5)F-. The energy differences between the different conformations were calculated using DFT methods, which is consistent to the experimental observations.
We reveal here a visible-light promoted phosphorylation of 2-isocyanoaryl thioethers for the first time with concomitant C(sp3)-S bond cleavage and imidoyl C-S formation. Additionally, this method features the use of 3 mol% organic dye Rose Bengal as the photocatalyst without external transition-metal or peroxide oxidants, and provides a novel and environmentally friendly approach for the preparation of a variety of 2-phosphoryl benzothiazoles in moderate to good yields.
The copper-catalyzed directed dearomatization of indoles with the assistance of directing groups has been developed for the synthesis of 2, 3-diazido indolines with good yields and excellent diastereoselectivities in aqueous solution. The resultant 2, 3-diazides can be smoothly converted to other functional groups, including vicinal diamines, triazoles and benzotriazoles, in a single step.
The rigidity of nanoparticles was newly reported to influence their oral delivery. Semi-elastic nanoparticles can enhance the penetration in mucus and uptake by epithelial cells. However, it is still challenging and unclear that the semi-elastic core-shell nanoparticles can enhance the oral bioavailability of peptide drugs. This study was for the first time to validate the semi-elastic coreshell poly(lactic-co-glycolic acid) (PLGA)-lipid nanoparticles (LNPs) as the carrier of the oral peptide drug. The antihypertensive peptide Val-Leu-Pro-Val-Pro (VP5) loaded LNPs (VP5-LNPs) were prepared by a modified thin-film ultrasonic dispersion method. Uptake experiment was performed in Caco-2 and HT-29 cells and monitored by high content screening (HCS) and flow cytometric (FCM). Pharmacokinetics of VP5-LNPs was carried out in Sprague-Dawley (SD) rats and analyzed by DAS 2.0. The optimal VP5-LNPs had an average particle size of 247.3±3.8 nm, zeta potential of -6.57±0.45 mV and excellent entrapment efficiency (EE) of 89.88%±1.23%. Transmission electron microscope (TEM) and Differential scanning calorimeter (DSC) further confirmed the core-shell structure. VP5-LNPs could increase the cellular uptake in vitro and have a 2.55-fold increase in AUC0-72 h, indicating a great promotion of the oral bioavailability. The semi-elastic LNPs remarkably improved the oral availability of peptide and could be a promising oral peptide delivery system for peptide drugs in the future.
Bioorthogonal cleavage and ligation reactions together form one more integrated system about the repertoire of bioorthogonal chemistry, capacitating an array of thrilling new biological applications. The bond-cleavage type and position of biomolecular remain a great challenge, which determines the metabolic pathway of the targets in living systems. Herein we designed two linkages of methylene and carbonyl group attached the N-3 position of the 5-ethynyl-2'-deoxyuridine (EdU) base or the oxygen atom at deoxyribose 3' position to a photocaging group, which would be cleaved by irradiation with 365 nm ultraviolet light. EdU derivatives linked by methylene at the N-3 position had better photodecage efficiency and stability in the absence of light. This paper provides a strategy for studying the nucleoside metabolic pathways in cells, which can easily and conveniently evaluate the effect of the position and type of the linkages. The developed strategy affords a reference for controlling spatial and temporal metabolism of small-molecule drugs, allowing direct manipulation of intact cells under physiological conditions.
Accurate quantitation of site-specific mRNA mutation in single cells or in peripheral blood is of great significance for both biological and biomedical studies. How to eliminate the false-positive interference from the abundant normal mRNA is still a big challenge. Herein, we have proposed an LNA (locked nucleic acid)-assisted high-specificity strategy which can selectively guide the RNase H to cleave only the wildtype mRNA (wtRNA) while the mutant mRNA (mutRNA) will remain intact. The intact mutRNA can be amplified and detected by real-time reverse transcription (RT)-PCR but the disconnected wtRNA will be not replicated at all. Based on the highly selective depletion of wtRNA, this elegant design effectively avoids the false-positive interference from the high background of normal mRNA and thus can guarantee the accurate and reliable detection of rare mutRNA in real biomedical samples. Besides for the excellent specificity, ultrahigh sensitivity is also achieved for this proposed assay, which allows the quantification of mutRNA at single molecule and single cell level. Due to its easy design, high sensitivity and specificity, the established LNA probe-assisted RT-PCR strategy provides a powerful tool for studying the function of mutRNA at the single cell level and for the mutRNA-associated liquid biopsy.
Hyperinoids A (1) and B (2), two prenylated acylphloroglucinol related meroterpenoids, were isolated from Hypericum patulum. Compound 1 incorporates an unprecedented 11, 12-dioxatetracyclo[5.4.3.01, 7.04, 14]tetradecane system, while 2 possesses a unique 10, 11-dioxatetracyclo[5.3.3.01, 7.04, 13] tridecane system. Their structures were established by spectroscopic analysis and X-ray crystallographic data. Compounds 1 and 2 were identified as potent NF-κB inhibitors and suppressed the LPS-induced inflammatory responses in RAW 246.7 macrophages and primary mouse BMDM cells
Mesoporous semiconducting metal oxides (SMOs) heterojunctions are appealing sensors for gas detecting. However, due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area, the synthesis of mesoporous SMOs heterojunctions with highly ordered mesostructures, highly crystallized frameworks, and high surface area remains a huge challenge. In this work, we develop a novel "acid-base pair" adjusted solvent evaporation induced self-assembly (EISA) strategy to prepare highly crystallized ordered mesoporous TiO2/WO3 (OM-TiO2/WO3) heterojunctions. The WCl6 and titanium isopropoxide (TIPO) are used as the precursors, respectively, which function as the "acid-base pair", enabling the coassembly with the structure directing agent (PEO-b-PS) into highly ordered mesostructures. In addition, PEO-b-PS can be converted to rigid carbon which can protect the mesostructures from collapse during the crystallization process. The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures, large pore size (~21.1 nm), highly crystalline frameworks and surface area (~98 m2/g). As a sensor for acetone, the obtained OM-TiO2/WO3 show excellent response/recovery performance (3 s/5 s), good linear dependence, repeatability, selectivity, and long-term stability (35 days).
(±)-Crataegusnorin A (1a/1b) and B (2a/2b), two pairs of rare 8, 9'-epoxy-type norlignan enantiomers featuring a γ-butyrolactone ring, were isolated from the fruit of Crataegus pinnatifida. Their structures were determined via extensive spectroscopic analyses. Gauge-independent atomic orbital (GIAO) NMR chemical shift calculations, combined with the advanced statistical method DP4+ were employed to establish the relative configurations of four compounds. Next, chiral separation was accomplished by chiral chromatographic column and the absolute configurations of the four compounds were unambiguously assigned by comparison between their experimental electronic circular dichroism curves with the quantum-mechanically calculated curves based on time-dependent density functional theory (TDDFT). All the isolates were evaluated for their neuroprotective activities against H2O2-induced cell injury in human neuroblastoma SH-SY5Y cells. The results showed that two pairs of enantiomers 1a/1b and 2a/2b displayed diff; erent effect on neuroprotective activity. Among them, compound 2a displayed the most potent neuroprotective effect. Further flow cytometry analysis indicated that 2a could protect SH-SY5Y cells from oxidative damage through inhibiting cell apoptosis.
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