Bioinspired manganese complexes catalyzed epoxidation for the synthesis of the epoxyketone fragment of carfilzomib

We report herein an efficient catalytic epoxidation reaction for the synthesis of epoxyketone (tert-butyl ((S)-4-methyl-1-((R)-2-methyloxiran-2-yl)-1-oxopentan-2-yl)carbamate), which is an important synthetic intermediate of carfilzomib.     

Reprint of: Recent advances in the functionalization of allenes via radical process

This review is focused on the recent advances in the functionalization of allenes via radical process. Different radical partners including carbon radicals and heteroatom radicals are discussed in the reactions of allenes. Generally, the radical formed in situ would attack the allene at the central carbon leading to allyl radical intermediate. However, the formation of alkenyl radical intermediate from allene could be observed as well in some cases with high regioselectivity and stereoselectivity.     

Preparation and in vitro/in vivo evaluation of anastrozole reservoir‐type intravaginal ring

This report details the preparation of anastrozole (ATZ) reservoir‐type intravaginal ring (IVR) and the detection of the concentration of ATZ in beagle dog plasma by liquid chromatography–tandem mass spectrometry (LC–MS/MS). An ATZ reservoir‐type IVR which included ATZ silicone elastomer core and a nonactive silicone layer was manufactured by reaction injection moulding at 80°C for 20 min. An in vitro release experiment was performed under sink conditions and the samples were determined by high‐performance liquid chromatography. A bioanalytical method was developed and validated for determination of ATZ in beagle dog plasma for IVR development. The analytical method consisted of the extraction of plasma samples and determination of ATZ by LC–MS/MS using buspirone as the internal standard. Separation was achieved on a Kinetex‐C₁₈ 110A column (3 × 30 mm, 2.6 μm, Phenomenex) using step‐gradient mobile phase and an isocratic flow rate consisting of formic acid. Protonated ions formed by a turboion spray in the positive mode was used to detect the analyte (ATZ) and internal standard. The MS–MS detection was performed on a triple quadrupole mass spectrometer equipped with electrospray ionization source. The mass spectrometer was operated in the multiple reaction monitoring mode. The mass transition ion‐pair was followed as m/z from 294.10 to 225.08 for anastrozole and m/z from 386.23 to 122.11 for buspirone. The results proved that the correlation between in vitro and in vivo analyses was relatively good.     

Characterization of the chemical constituents in Hongjingtian injection by liquid chromatography quadrupole time‐of‐flight mass spectrometry

Hongjingtian injection is made from Rhodiola wallichiana and used in the treatment of stable angina pectoris associated with coronary heart disease. In this study, the chemical constituents in Hongjingtian injection were comprehensively studied using liquid chromatography quadrupole time‐of‐flight mass spectrometry. A total of 49 compounds were identified or assumed, including 10 organic acids, nine phenylethanoids, 10 phenylpropanoids, two flavonoid glycosides, seven monoterpene glycosides, seven octylglycosides and four other types of compounds. The structures of seven compounds were confirmed by comparing their retention times, MS and UV spectra with the corresponding authentic standards. Amongst the 49 compounds, 35 were firstly found in R. wallichiana, while they have been reported in other species of the genus Rhodiola, including Rhodiola crenulata, Rhodiola sacra, Rhodiola rosea and Rhodiola kirilowii. The possible fragmentation pathways in the mass spectrometry of the major types of compounds are proposed and summarized. Our study demonstrates a rapid method for characterizing the chemical constituents present in the Hongjingtian injection, which could also be applied to the identification of chemical constituents in other TCM formulae containing R. wallichiana.     

Strain‐Induced Isomerization in One‐Dimensional Metal–Organic Chains

The ability to use mechanical strain to steer chemical reactions creates completely new opportunities for solution‐ and solid‐phase synthesis of functional molecules and materials. However, this strategy is not readily applied in the bottom‐up on‐surface synthesis of well‐defined nanostructures. We report an internal strain‐induced skeletal rearrangement of one‐dimensional (1D) metal–organic chains (MOCs) via a concurrent atom shift and bond cleavage on Cu(111) at room temperature. The process involves Cu‐catalyzed debromination of organic monomers to generate 1,5‐dimethylnaphthalene diradicals that coordinate to Cu adatoms, forming MOCs with both homochiral and heterochiral naphthalene backbone arrangements. Bond‐resolved non‐contact atomic force microscopy imaging combined with density functional theory calculations showed that the relief of substrate‐induced internal strain drives the skeletal rearrangement of MOCs via 1,3‐H shifts and shift of Cu adatoms that enable migration of the monomer backbone toward an energetically favorable registry with the Cu(111) substrate. Our findings on this strain‐induced structural rearrangement in 1D systems will enrich the toolbox for on‐surface synthesis of novel functional materials and quantum nanostructures.     

Resolving quantum dots and peptide assembly and disassembly using bending capillary electrophoresis

Despite the numerous techniques developed for the studying nanoparticle and peptide interaction nowadays, sensitive and convenient assay in the process of flow, especially to simulate the self‐assembly of quantum dots (QDs) and peptide inflow in blood vessels, still remains big challenges. Here, we report a novel assay for studying the self‐assembly of QDs and peptide, based on CE using a bending capillary. We demonstrate that the semicircles numbers of the bending capillary affect the self‐assembly kinetics of CdSe/ZnS QDs and ATTO‐D₃LVPRGSGP₉G₂H₆ peptide. Moreover, benefitting from this novel assay, the effect of the position on the self‐assembly has also been realized. More importantly, we also demonstrate that this novel assay can be used for studying the stability of the QDs–peptide complex inflow. We believe that our novel assay proposed in this work could be further used as a general strategy for the studying nanoparticle–biomolecule interaction or biomolecule–biomolecule interaction.     

Electrochemical Monitoring of ROS/RNS Homeostasis Within Individual Phagolysosomes Inside Single Macrophages

The existence of a homeostatic mechanism regulating reactive oxygen/nitrogen species (ROS/RNS) amounts inside phagolysosomes has been invoked to account for the efficiency of this process but could not be unambiguously documented. Now, intracellular electrochemical analysis with platinized nanowire electrodes (Pt‐NWEs) allowed monitoring ROS/RNS effluxes with sub‐millisecond resolution from individual phagolysosomes impacting onto the electrode inserted inside a living macrophage. This shows for the first time that the consumption of ROS/RNS by their oxidation at the nanoelectrode surface stimulates the production of significant ROS/RNS amounts inside phagolysosomes. These results establish the existence of the long‐postulated ROS/RNS homeostasis and allows its kinetics and efficiency to be quantified. ROS/RNS concentrations may then be maintained at sufficiently high levels for sustaining proper pathogen digestion rates without endangering the macrophage internal structures.     

Encapsulation of a Phase‐Change Material in Nanocapsules with a Well‐Defined Hole in the Wall for the Controlled Release of Drugs

As a class of biocompatible and biodegradable phase‐change materials, natural fatty acids have received considerable interest in recent years for temperature‐controlled release of drugs. However, the poor dispersibility and colloidal stability of their nanoparticles under physiological conditions place a major limitation on their applications in biomedicine. Herein, we report a facile method for encapsulating a mixture of two natural fatty acids (with a eutectic melting point at 39 °C) in a biocompatible, silica‐based nanocapsule to achieve both stable dispersion and controllable release of drugs. The nanocapsules have a well‐defined hole in the wall to ensure easy loading of fatty acids, together with multiple types of functional components such as therapeutics and near‐infrared dyes. The payloads can be released through the hole when the fatty acids are melted upon photothermal heating. The release profile can be controlled by varying the size of the hole and/or the duration of laser irradiation.     

5-(4-羟基苯基)-2,4-咪唑啉二酮酯类化合物的合成及其生物活性

在模拟AdSS酶天然抑制剂结构合成5-(4-羟基苄基)-2,4-咪唑啉二酮酯系列化合物的基础上,为优化其结构,以5-(4-羟基苯基)-2,4-咪唑啉二酮为中间体,合成了28个未见文献报道的5-(4-羟基苯基)-2,4-咪唑啉二酮羧酸酯类化合物,它们的结构均经IR,1HNMR和元素分析表征.初步生物活性测试表明目标化合物5-(4-羟基苯基)-2,4-咪唑啉二酮对叔丁基苯甲酸酯(2i)和2-噻吩酸酯(3b)在浓度200μg/mL时对拟南芥生长抑制率达70%..