新型小檗碱衍生物的合成及其体外降糖活性

为提高小檗碱的水溶性以及降糖活性，对其C-9位进行了结构修饰，合成了6个9-O-小檗碱酯类衍生物（3a~3f），其中3b~3d和3f为新化合物，其结构经¹H NMR， IR和HR-MS(ESI)表征。选用人肝癌细胞（HepG2）建立胰岛素抵抗模型（HepG2-IR），通过MTT法研究了3a~3f的体外降糖活性。结果表明：3a~3f均具有不同程度的降糖活性，其中化合物3a(IC₅₀=0.044 ±0.97 mg·L^-1)在低浓度0.08 mg·L^-1时，对HepG2-IR细胞葡萄糖消耗量为3.5 mM，优于小檗碱(2.75 mM)。     

Stereoselective synthesis of (+)-SCH 351448: a unique ligand system for sodium, calcium, and other cations

(+)-SCH 351448 (Na+ salt A) was synthesized employing ring-closing olefin metathesis reaction of an open diene diester intermediate for construction of the 28-membered macrodiolide structure. The open diene diester was prepared from the monomeric hydroxy carboxylic acid and two different olefin fragments. The monomeric hydroxy acid was synthesized via Julia-Julia coupling reaction of intermediates derived from the same olefinic fragments. Oxane units in these fragments were prepared by radical cyclization reactions of beta-alkoxyacrylates. Analogous SCH 351448 salts incorporating other mono- and divalent cations may be prepared. Under acidic conditions, SCH 351448 (Na+ salt A) was the most stable complex, but SCH 351448 (Ca2+ salt) and (Na+ salt B) appear to be physiologically important species.     

A Novel Method for the Synthesis of Substituted Benzochromenes by Ethylenediamine Diacetate‐Catalyzed Cyclizations of Naphthalenols to α,β‐Unsaturated Aldehydes. Concise Synthesis of the Natural Products Lapachenole,Dihydrolapachenole, and Mollugin

A new synthetic route for biologically interesting benzochromenes was developed starting from naphthalenols and α,β‐unsaturated aldehydes in the presence of ethylenediamine diacetate. This methodology was applied for the total synthesis of the biologically important natural products lapachenole, dihydrolapachenole, and mollugin with a benzochromene moiety.     

硅的原子吸收光谱分析进展

对近十年来用原子吸收光谱法测定硅的情况进行评述．重点介绍用石墨炉测定硅时，为了避免硅与石墨炉中碳形成难熔碳化硅影响测定硅的灵敏度而使用的各种化学改进剂，涂层石墨管和一些新的实验技术．引用参考文献４２篇．     

The structural phase transitions of aminoguanidinium(1+) dihydrogen phosphate—study of crystal structures, vibrational spectra and thermal behavior

Aminoguanidinium(1+) dihydrogen phosphate was prepared by crystallization from aqueous solution. On the basis of the results of DSC measurements, X-ray structural analysis was carried out at temperatures of 160, 215 and 293 K for three aminoguanidinium(1+) dihydrogen phosphate phases ( |Z=2|non-ferroic |melting point 408 K; II |201-222 K|(2) |Z=2|non-ferroic|-; III |<201 K|(2)|Z=4|non-ferroic|-). The triclinic unit cell dimensions (a=6.8220(2), b=7.1000(2), c=7.4500(2) Å, α=86.925(2)°, β=80.731(2)°, γ=79.630(2)°, V=350.21(2) Å³—phase I) are similar for all three structural phases with the exception of phase III, where doubling of the c-axis length leads to an increase in the volume to 692.34(3) Å³. The crystal structure of all three modifications consists of parallel layers of dihydrogen phosphate anions that are interconnected by aminoguanidinium(1+) cations through hydrogen bonds of the N-H…O type. The planar aminoguanidinium(1+) cations are oriented almost parallel to each other and are perpendicular to the anion layers. The primary differences amongst phases I, II and III lie in the location of the H atom in the short O-H…O bonds connecting the dihydrogen phosphate anions in layers. The FTIR and FT Raman spectra of natural and deuterated compounds were recorded and interpreted. The FTIR spectra were studied down to a temperature of 90 K.     

Kinesin superfamily protein member 4 (KIF4) is localized to midzone and midbody in dividing cells

In association with microtubules, a variety of kinesins play important roles in cellular functions such as intracellular transport of organelles or vesicles, signal transduction, and cell division. In a previous study we revealed that human kinesin superfamily protein member 4 (KIF4) is a chromokinesin that binds to chromosomes. Since localization of several kinds of kinesin at midzone called central spindle, or midbody that connects two daughter cells, or both, suggests their implication in cell division, we investigated KIF4 localization of during mitosis and cytokinesis in Hela cells. In addition to association with segregating chromosomes through entire mitosis, it also localized to the midzone and to midbody at ana/telophase through cytokinesis. Especially in cells at cytokinesis, KIF4 appeared as a doublet facing each other at the apical ends of two daughter cells. Three- dimensional analysis of architectural relationship between microtubule bundles and KIF4 indicated that KIF4 forms a ring structure wrapping around the microtubule bundles. These results suggest that KIF4 is involved in cytokinesis, although direct evidence was not provided in this study.     

Thin-Layer Chromatographic Analysis of Flavonoids,Phenolic Acids,and Amino Acids in Some Croatian Hypericum Taxa

JPC – Journal of Planar Chromatography – Modern TLC - The flowering tops of Hypericum hirsutum, H. montanum, H. perforatum subsp. angustifolium, H. perforatum subsp. perforatum, and H....     

(C(wedge)N(wedge)N)Pt(C identical to C)nR] (HC(wedge)N(wedge)N = 6-aryl-2,2'-bipyridine,n = 1-4, R = aryl,SiMe3) as a new class of light-emitting materials and their applications in electrophosphorescent devices

Tridentate cyclometalated platinum(II) complexes bearing sigma-alkynyl ligands exhibit tunable photoluminescence and enhanced stability during vacuum deposition; OLEDs based on these materials display orange to red electrophosphorescence with low turn-on voltages (approximately 4 V), maximum luminance approaching 10,000 cd m-2 and efficiency up to 4.2 cd A-1.     

Reactivity of iron(II) 5,10,15,20-tetraaryl-21-oxaporphyrin with arylmagnesium bromide: formation of paramagnetic six-coordinate complexes with two axial aryl groups

Coordination of sigma-aryl carbanions by chloroiron(II) 5,20-ditolyl-10,15-diphenyl-21-oxaporphyrin (ODTDPP)Fe(II)Cl has been followed by (1)H NMR spectroscopy. Addition of pentafluorophenyl Grignard reagent (C(6)F(5))MgBr to the toluene solution of (ODTDPP)Fe(II)Cl in the absence of dioxygen at 205 K resulted in the formation of the high-spin (ODTDPP)Fe(II)(C(6)F(5)). The titration of (ODTDPP)Fe(II)Cl with a solution of (C(6)H(5))MgBr carried at 205 K yields a rare six-coordinate species which binds two sigma-aryl ligands [(ODTDPP)Fe(II)(C(6)H(5))(2)](-). Warming of the [(ODTDPP)Fe(II)(C(6)H(5))(2)](-) solution above 270 K results in the decomposition to mono-sigma-phenyliron species (ODTDPP)Fe(II)(C(6)H(5)). Controlled oxidation of [(ODTDPP)Fe(II)(C(6)H(5))(2)](-) with Br(2) affords (ODTDPP)Fe(III)(C(6)H(5))Br, which demonstrates a typical (1)H NMR pattern of low-spin sigma-aryl iron(III) porphyrin. The considered oxidation mechanism involves the (ODTDPP)Fe(III)(C(6)H(5))(2) species, which is readily reduced to the iron(I) 21-oxaporphyrin, followed by oxidation with Br(2) and replacement of one bromide anion by aryl substituent. The (1)H NMR spectra of paramagnetic iron complexes have been examined in detail. Functional group assignments have been made with the use of selective deuteration. The peculiar (1)H NMR spectral features of [(ODTDPP)Fe(II)(p-CH(3)C(6)H(4))(2)](-) (sigma-p-tolyl: ortho, 30.8; meta, 53.6; para-CH(3), 42.1; furan: -16.0; beta-H pyrrole: -27.5, -34.3, -41.8 ppm, at 205 K) are without a parallel to any iron(II) porphyrin or heteroporphyrin and indicate a profound alteration of the electronic structure of iron(II) porphyrin upon the coordination of two sigma-aryls.     

Cure behavior and thermal stability of an epoxy: new bismaleimide blends for composite matrices

A new bismaleimide (BMI) resin was synthesized to formulate epoxy(tetraglycidyl diaminodiphenyl methane; TGDDM) – bismaleimide thermoset blends for composite matrix applications. 4,4′-diaminodiphenyl methane (DDM) was used as an amine curing agent for the TGDDM. A Fourier transform infrared (FTIR) spectroscopy was employed to characterize the new BMI resin. Cure behavior of the epoxy–BMI blends was studied using a differential scanning calorimeter (DSC). DSC thermograms of the thermoset blends indicated two exothermic peaks. The glass transition temperature of the thermoset blends decreased with BMI content. Thermogravimetric analysis (TGA) was carried out to investigate thermal degradation behavior of the cured epoxy–BMI thermoset blends. The new BMI resin reacted partially with the DDM and weak intercrosslinking polymer networks were formed during cure of the thermoset blends.