Elution–extrusion counter-current chromatographic separation and theoretical mechanism of antioxidant from Robinia pseudoacacia flower

Robinia pseudoacacia flowers have attracted much attention because of numerous bioactivities. In this study, its extract showed the potential scavenging ability for 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate) and 1,1-diphenyl-2-picrylhydrazyl free radicals. Under the guidance of antioxidant activity, the antioxidant extract was enriched by liquid-liquid extraction. The partition coefficients of the two main components in antioxidant extracts differed greatly, so in this study, elution-extrusion counter-current chromatography with the solvent system of n-hexane-ethyl acetate-methanol-water (2.5:5:2.5:5, v/v) was used to enhance the separation efficiency, and the two main components were successfully obtained. Among them, kaempferol showed strong antioxidant activity, which can be responsible for the activity of the extract. In order to deeply understand the antioxidant mechanism of kaempferol, the thermodynamics, frontier molecular orbital, and kinetics of scavenging free radicals were investigated by density functional theory. The results showed that 4′-OH in kaempferol was the most active group, which can scavenge free radicals by hydrogen atom transfer in non-polar solvents and activate 3-OH to generate double hydrogen atom transfer in the gas phase. But in polar solvents, it was more inclined to clear radicals through single electron transfer and proton transfer. The kinetic result showed that kaempferol needed 9.17 kcal/mol of activation energy to scavenge free radicals.     

A Covalent Binding Mode of a Pyrazole-Based CD38 Inhibitor

Brain concentrations of nicotinamide adenine dinucleotide (NAD⁺), an important cellular co-factor, tend to decrease with age and in neurodegeneration. As the NADase cluster of differentiation 38 (CD38) significantly contributes to NAD⁺ consumption, we reasoned that CD38 inhibition may be of therapeutic value for CNS disorders. The new pyrazole compound was designed based on a known CD38 inhibitor and showed good inhibitory potency. Several attempts to co-crystallise this pyrazole with CD38 and cyclic adenosine diphosphate ribose (cADPR) culminated in a high-resolution X-ray structure, in which the pyrazolyl group in the new compound formed a covalent bond with one of the ribosyl units of cADPR. This reaction proceeded under retention of configuration and resulted in a neutral ribosyl-pyrazole conjugate that is embedded within the active site of the enzyme. An analysis of this structural complex gave rise to design principles that enabled the preparation of more potent CD38 inhibitors with drug-like properties.     

Experimental study on synchrotron radiation photoionization of secondary organic aerosol derived from styrene ozonolysis

Secondary organic aerosol (SOA) produced by ozonolysis of styrene and other alkene compounds is a major part of fine particles in urban atmospheres. The atmospheric ozonolysis process of styrene is simulated in a smog chamber, and the formed SOA particles are detected on-line by a synchronous radiation vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) in this study. Through molecular ion peaks in the photonionization mass spectra of SOA and the corresponding photoionization efficiency curve, combined with off-line measurement verification of ultraviolet visible and infrared absorption spectra, it is determined that formaldehyde, formic acid, benzene, phenol, benzaldehyde, and benzoic acid are the main constituents of styrene SOA. These provide new information for studying the atmospheric ozonolysis oxidation mechanism of styrene. VUV-PIMS can get over complicated sample preparation procedures, secondary pollution, and other shortcomings of the off-line method and is a useful instrument to measure constituents and unveil the formation process of SOA particles.     

环境响应性微胶囊及其在农业领域中应用的研究进展

在传统农业中,如何高效率地使用农药,提高其利用率,一直是一大难题。环境响应性微胶囊是一类在外界环境的刺激下,可以相适应地改变其表面结构的物质。这一类微胶囊具有智能、可控、精准、高效等特点。目前,这一项技术已经被广泛地应用于农业生产中。本文主要综述了环境中pH、温度、光以及磁场四大因素对响应性微胶囊的影响,并且简要介绍了该类微胶囊的制备技术、形成机理、主要材料以及在农业领域的应用。     

The Universal Super Cation-Conductivity in Multiple-cation Mixed Chloride Solid-State Electrolytes

As exciting candidates for next-generation energy storage, all-solid-state lithium batteries (ASSLBs) are highly dependent on advanced solid-state electrolytes (SSEs). Here, using cost-effective LaCl₃ and CeCl₃ lattice (UCl₃-type structure) as the host and further combined with a multiple-cation mixed strategy, we report a series of UCl₃-type SSEs with high room-temperature ionic conductivities over 10⁻³ S cm⁻¹ and good compatibility with high-voltage oxide cathodes. The intrinsic large-size hexagonal one-dimensional channels and highly disordered amorphous phase induced by multi-metal cation species are believed to trigger fast multiple ionic conductions of Li⁺, Na⁺, K⁺, Cu⁺, and Ag⁺. The UCl₃-type SSEs enable a stable prototype ASSLB capable of over 3000 cycles and high reversibility at −30 °C. Further exploration of the brand-new multiple-cation mixed chlorides is likely to lead to the development of advanced halide SSEs suitable for ASSLBs with high energy density.     

Organocatalytic asymmetric [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with enals: Efficient approach to functionalized spiro N-heterocyclic oxindoles

An unprecedented chiral secondary amine-catalyzed [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes was developed. This strategy allowed the construction of structurally novel spiro N-heterocyclic oxindole derivatives in good yields (up to 91%) and good to excellent enantioselectivities (up to >99% ee), albeit with modest diastereoselectivities (up to 3.1:1 dr).     

Design,synthesis, and insecticidal activities of novel diamide derivatives with alpha-amino acid subunits

A series of diamide derivatives containing α-amino acids were designed and synthesized. These compounds were evaluated for their insecticidal activities against Plutella xylostella, Mythimna separate, Myzus persicae, and Tetranychus cinnabarinus. Most of the title compounds containing an l -phenylglycine skeleton were endowed with good activities at the concentration of 500 mg·L⁻¹. Compounds ( R)-A6 showed a potential value for further optimization as an insecticidal lead with the LC₅₀ value of 86.8 mg·L⁻¹.     

吲哚多样化环化合成咔唑衍生物研究进展

咔唑是一类特殊的含氮芳杂环分子,咔唑衍生物理化性质独特、结构多样,在天然产物、药物和功能材料领域有着广阔的应用,其合成方法一直备受关注.从吲哚直接环化到咔唑的合成方法简洁高效,原料廉价易得、产物种类多样.总结了近5年来以2,3-未取代吲哚为原料合成咔唑衍生物的方法,典型环化策略包含以下三种:[2+2′+2′]环化反应、[2+2′+2″]环化反应和[4+2]苯环化反应,探讨了每种方法的特点,并对未来的发展前景进行展望.     

A bio‐safe cyclophosphazene derivative flame retardant for polylactic acid composites: Flammability and cytotoxicity

An efficient bio‐safe cyclophosphazene flame retardant, 1,5,9,13,16,20‐Hexaoxa‐7,14,21‐triaza‐6λ⁴,8λ⁴,5λ⁴‐triphosphatrispiro[5.1.5.1.5.1]heneicosa‐6,8(14),15(21)‐triene (HCPO), was synthesized, and then was incorporated into polylactic acid (PLA) to improve the fire safety. The chemical structure of HCPO was confirmed by Fourier‐transformed infrared spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy. The thermal stability of the compound was characterized by thermogravimetric (TG) analyzer. The cytotoxic effects of HCPO to cells were evaluated. Fire behavior and thermal stability of PLA composites were investigated by vertical burning, limiting oxygen index (LOI), TG analysis, and cone calorimeter. The morphology of residual charring was observed by scanning electron microscope. The results showed HCPO was bio‐safe, and highly effective to enhance the flame retardancy of PLA composites. The LOI value was increased from 18.4 to 27.5 and UL‐94 grade achieved V‐0 for the PLA composite containing only 2% HCPO and 2% pentaerythrotol. It was demonstrated that intermolecular cross‐linking reaction between pentaerythrotol and HCPO in high temperature range could accelerate the formation of compact char layers.     

Multi-functional cotton textiles design using in situ generating zeolitic imidazolate framework-67 (ZIF-67) for effective UV resistance,antibacterial activity,and self-cleaning

Cellulose - In this study, a multifunctional cotton fabric with durable superhydrophobic, antibacterial, and UV resistance properties was prepared by in situ growth of zeolitic imidazolate...