Structural and Functional Implications of the Interaction between Macrolide Antibiotics and Bile Acids

Macrolide antibiotics, such as azithromycin and erythromycin, are in widespread use for the treatment of bacterial infections. Macrolides are taken up and excreted mainly by bile. Additionally, they have been implicated in biliary system diseases and to modify the excretion of other drugs through bile. Despite mounting evidence for the interplay between macrolide antibiotics and bile acids, the molecular details of this interaction remain unknown. Herein, we show by NMR measurements that macrolides directly bind to bile acid micelles. The topology of this interaction has been determined by solvent paramagnetic relaxation enhancements (solvent PREs). The macrolides were found to be bound close to the surface of the micelle. Increasing hydrophobicity of both the macrolide and the bile acid strengthen this interaction. Both bile acid and macrolide molecules show similar solvent PREs across their whole structures, indicating that there are no preferred orientations of them in the bile micelle aggregates. The binding to bile aggregates does not impede macrolide antibiotics from targeting bacteria. In fact, the toxicity of azithromycin towards enterotoxic E. coli (ETEC) is even slightly increased in the presence of bile, as was shown by effective concentration (EC₅₀) values.     

Impact of the flexibility of pillar linkers on the structure and CO_2 adsorption property of ‘‘pillar-layered' MOFs

A new metal–organic framework {[Zn_2(bpta)(bpy-ee)(H_2O)_2]·x solve}_n(1)(H_4bpta = biphenyl-2,20,6,60-tetracarboxylic acid and bpy-ee = 1,2-bis(4-pyridyl)ethylene) has been obtained under hydrothermal condition, and structurally characterized by single-crystal X-ray diffraction. Complex 1 reveals a threedimensional(3D) ‘‘pillar-layered' framework with non-flexible linker, in which some different structure characters can be found compared to that of some related other ‘‘pillar-layered' MOFs based on flexible pillar linkers. It demonstrates the impact of the flexibility of pillar linker on the final structure in this system. In addition, the selective CO_2 adsorption performance of 1 was also investigated.     

地方工科院校《功能高分子材料》课程教学内容的精选与实践

随着材料学的蓬勃发展,功能高分子材料的种类及用途日益繁多,因而《功能高分子材料》课程教学内容涵盖也不断延伸。针对地方工科院校高分子材料与工程专业人才培养的机制和目标,作者探索实践了如何以学生为本、以社会和行业的人才需求为导向,紧密联系地方经济与行业格局,因时因势对课程教学内容进行优化和完善。在此基础上,通过科学合理的教学实践,使学生既能牢固掌握功能高分子材料的基础知识,又能了解本领域最前沿的科学发展动态,拓宽学习思路,提高学习积极性,增强对专业的认可与对行业的期待。     

Double-stranded ladderphanes with C2-symmetric planar chiral ferrocene linkers

Eight ladderphanes with C₂-symmetric planar chiral ferrocene linkers are synthesized by ring opening metathesis polymerization of bisnorbornene monomers using Grubbs-I catalyst. The aminobenzoate in both monomers and polymers shows absorption maximum around 320 nm. Both monomers and polymers are Circular dichroism (CD) active. Little enhancements of CD profiles around 320 nm are observed for ladderphanes having chiral chloro- or phenyl-substituted ferrocene linkers. However, ladderphanes with a phenyl substituent on the cyclopendienyl ring exhibits enhancement of CD curves aound 240–300 nm. The congested phenyl moieties in adjacent linkers in this polymer might be well oriented such that interactions between these aromatic substituents on different monomeric units might provoke the enhancement of the CD curves in this region. When the methyl-substituted cyclopendienyl ligand is used for chiral ferrocene linkers, the ladderphanes exhibit two-fold enhancement of CD spectrum around 320 nm. This enhancement is further increased when the cyclopentadienyl ligand contains an additional phenyl substituent, owing to exciton coupling between aminobenzoate moieties in adjacent monomeric units. Moreover, the intensity of the CD curves in the region of 240–300 nm is significantly increased. These results suggest that the later polymer may adopt a posible helical structure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2999–3010     

A Liouville theorem for weighted p−Laplace operator on smooth metric measure spaces

We prove that on a smooth metric measure space with m ?Bakry–Émery curvature bounded from below by ?(m ? 1)K for some constant K ≥0 (i.e., Ric_{f ,m} ≥?(m ? 1)K ), the following degenerate elliptic equation (0.1) has no nonconstant positive solution when p > 1 and constant λ _{f ,p} satisfies Our approach is based on the local Sobolev inequality and the Moser's iterative technique and is different from Cheng‐Yau's method, which was used by Wang‐Zhu in 2012 to derive a same Liouville theorem when 1 < p ≤2, Ric_{f ,m} ≥?(m ? 1)K and the sectional curvature is bounded from below. Copyright © 2016 John Wiley & Sons, Ltd.     

Sesquiterpenoids from the Fruits of Alpinia oxyphylla and Their Anti‐Acetylcholinesterase Activity

Fourteen sesquiterpenoids were isolated from the fruits of Alpinia oxyphylla Miq . Their structures were elucidated based on NMR analyses (¹H, ¹³C, DEPT, ¹H,¹H‐COSY, HMQC, HMBC, and NOESY) and identified as 12‐nornootkaton‐6‐en‐11‐one ( 3 ), (+)‐(3S,4aS,5R)‐2,3,4,4a,5,6‐hexahydro‐3‐isopropenyl‐4a,5‐dimethyl‐1,7‐naphthoquinone ( 5 ), nootkatene ( 6 ), 9β‐hydroxynootkatone ( 7 ), 2β‐hydroxy‐δ‐cadinol ( 8 ), 4‐isopropyl‐6‐methyl‐1‐tetralone ( 11 ), oxyphyllone E ( 12 ), oxyphyllone D ( 13 ), oxyphyllanene B ( 15 ), oxyphyllone A ( 16 ), oxyphyllol E ( 17 ), (9E)‐humulene‐2,3;6,7‐diepoxide ( 18 ), mustakone ( 20 ), and pubescone ( 21 ). Among them, 3 was a new norsesquiterpenoid, 8 was a new natural product, and 5, 6, 11, 20, 21 were isolated from A. oxyphylla for the first time. Twenty sesquiterpenoids, 1 – 5 and 7 – 21 , were investigated for their in vitro acetylcholinesterase (AChE) inhibitory activities, including previously isolated seven sesquiterpenoids from A. oxyphylla, (11S)‐12‐chloronootkaton‐11‐ol ( 1 ), (11R)‐12‐chloronootkaton‐11‐ol ( 2 ), nootkatone ( 4 ), oxyphyllenodiol A ( 9 ), oxyphyllenodiol B ( 10 ), 7‐epiteucrenone B ( 14 ), and alpinenone ( 19 ). TLC‐Bioautographic assay indicated that 1 – 4, 7, 14, 16, 18, 19 , and 21 displayed anti‐AChE activities at 10 nmol. Microplate assay confirmed that 19, 18, 16 , and 21 displayed moderate‐to‐weak anti‐AChE activities at the concentration of 100 μM , and 19 was the most potent inhibitor with an IC₅₀ value of 81.6±3.5 μM . The presence of anti‐AChE sesquiterpenoids in A. oxyphylla may partially support the traditional use of this fruit for the treatment of dementia.     

新型C-异戊烯基香豆素的合成

以7-羟基香豆素或7-羟基-4-甲基香豆素为原料,通过异戊烯基化反应合成了四个新的C-异戊烯基香豆素,其结构经1H NMR,IR和MS表征.     

Electrochemical Detection of Catechol on Boron‐doped Diamond Electrode Modified with Au/TiO2 Nanorod Composite

Au/TiO₂ nanorod composites with different ratios of [TiO₂]:[Au] have been prepared by chemically reducing AuCl₄^‐ on the positively charged TiO₂ nanorods surface and used to modify boron‐doped diamond (BDD) electrodes. The electrochemical behaviors of catechol on the bare and different Au/TiO₂ nanorod composites‐modified BDD electrodes are studied. The cyclic voltammetric results indicate that these different Au/TiO₂ nanorod composites‐modified BDD electrodes can enhance the electrocatalytic activity toward catechol detection, as compared with the bare BDD electrode. Among these different conditions, the Au/TiO₂‐BDD3 electrode (the ratio of [TiO₂]:[Au] is 27:1) is the most choice for catechol detection. The electrochemical response dependences of the Au/TiO₂‐BDD3 electrode on pH of solution and the applied potential are studied. The detection limit of catechol is found to be about 1.4 × 10^‐6 M in a linear range from 5 × 10^‐6 M to 200 × 10^‐6 M on the Au/TiO₂‐BDD3 electrode.     

Isometric Extension Problem Between Strictly Convex Two-dimensional Normed Spaces

In this paper, based on the smooth point of the unit ball and its support linear functional,we show two equivalent formulations of the isometric extension problem between the unit spheres of strictly convex two-dimensional normed spaces. We prove that these equivalent formulations have a positive answer in a special case.     

Synthesis of Polynorbornene-Poly(ethylene-co-propylene)Diblock Copolymer

IntroductionSincethefirstexampleofobtaininglivingpolymersfrompolymerizations0fstyreneandisoprenebyusingsodiumnaphthenateasananionicinitiat0rwasdiscl0sedinl956bySzwarc',avarietyoftailoredblockcopolymershavebeensynthesized.Livingpolymerizati0ncanbeappliedtoprepareblockcopolymerswithawiderangeofpropertiesnotattainablewithhom0polymersorrandomcopolymers'.Duringtherecentdecade,thesynthesesofwell-definedtransition-metalalkylidenec0mPlexes"'haveprovidedeffectivecatalystsforlivingring-openingmetathesi…