A new C21-steroidal glycoside from Cynanchum stauntonii

A new C21-steroidal glycoside with two known compounds were isolated from the root of Cynanchum Stauntonii.Based on thespectral analysis,including MS,1H NMR,13C NMR,DEPT,1H-1H COSY,13C-1H COSY,HMQC and HMBC,their chemicalstructures were determinated as glaucogenin-C 3-O-a-L-cymaropyranosyl-(1→4)-b-D-digitoxopyranosyl-(1→4)-β-D-canaropyranoside(1),stigmasterol(2)and ursolic acid(3).     

Host-guest complexes of cucubit[8]uril with phenanthrolines and some methyl derivatives

Cucurbituril a molecular container (or host) has a rigid hollow interior cavity which is large enough to accommodate, one or more, smaller molecules (or guests). The cavity is accessible through two carbonyl portal openings. Molecules or guests enter the …     

Synthesis and Characterization of Tetraosmium Carbonyl Complexes Containing a Bridging CO2 Ligand

Treatment of (thd)H (thd=2,2,6,6-tetramethyl-3,5-heptandionate) with excess Os₃(CO)₁₂ in an autoclave at 180°C gives the formation of a brown metal chain complex [Os₂(CO)₅(thd)₂]₂ (1) and a yellow CO₂ cluster complex [Os₄(-H)(-CO₂)(thd)(CO)₁₃] (2) in low yields. Complex 2 was fully identified by a combination of spectroscopic methods and X-ray diffraction study, showing a unique CO₂ ligand bridging a triosmium metal fragment, Os₃(-H)(CO)₁₀ and a monometallic osmium fragment, Os(CO)₃(thd). Upon treatment of 1 with Me₃NO at an elevated temperature, oxidation of the CO ligand occurred at the position trans to the unique CO₂ ligand on the Os(CO)₃(thd) fragment, giving the formation of a second CO₂ cluster [Os₄(-H)(-CO₂)(thd)(CO)₁₂(NCMe)] (3), which is stabilized by a weakly coordinated acetonitrile molecule.     

偏最小二乘-同步荧光法测定人尿中黄蝶呤

建立了人尿中黄蝶呤含量测定的同步荧光分析方法。在pH 7.8 KH2PO4-NaOH缓冲溶液中,于Δλ为70 nm的条件下对黄蝶呤及其它蝶呤类化合物进行同步荧光扫描,所得的重叠波谱数据用主成分回归法(PCR)、偏最小二乘法(PLS)、经典最小二乘法(CLS)和径向基人工神经网络(RBF-ANN)等多元校正法进行处理,结果表明偏最小二乘法(PLS)的分析结果最好,其标准偏差为4.29%。该方法简便、快速、准确,避免了较繁琐的样品前处理过程,应用于人尿中黄蝶呤分析,结果令人满意。     

The interfacial dilational properties of hydrophobically modified associating polyacrylamide studied by the interfacial tension relaxation method at an oil-water interface

The interfacial dilational viscoelastic properties of hydrophobically associating block copolymer composed of acrylamide (AM) and a low amount of 2-phenoxylethyl acrylate (POEA) (<1.0 mol%) at the octane-water interfaces were studied by means of the interfacial tension relaxation method. The dependencies of interfacial dilational elasticity and viscous component on the dilational frequency were investigated. The interaction of hydrophobically associating block copolymer [P(AM/POEA)] with sodium dodecyl sulfate (SDS) has been explored. The results show that at lower frequency, the dilational elasticity for different concentration copolymer is close to zero; at higher frequency, the dilational elasticity shows no change with increased frequency; At moderate frequency (10(-3)-1 Hz), the dilational elasticity decreased with a decrease in the dilational frequency. The results show that the hydrophobic groups of [P(AM/POEA)] chains can be associated by inter- or intrachain liaisons in water solution. The dilational viscous component for P(AM/POEA) comes forth a different maximum value at different frequencies when the polymer concentration is different. It is generally believed that the dilational viscous component reflects the summation of the various microscopic relaxation processes at and near the interface and different relaxation processes have different characteristic frequencies. The spectrum of dilational viscous component may appear more than once maximum values at different frequencies. The influence of SDS on the limiting dilational elasticity and viscous component for polymer solution was elucidated. For 5000 ppm polymer solution, the limiting dilational elasticity decreased with an increase in SDS concentration. The dilational viscous component passed through a maximum value with a rise in the dilational frequency, which appeared at different frequency when SDS concentration is different; and the higher is the concentration, the lower is the dilational frequency. It can be explained that macromolecules may be substituted by SDS molecules in the interface and the interaction of molecules decrease, which makes the limiting dilational elasticity decrease. For 200 ppm polymer solution, the limiting dilational elasticity increased firstly and then decreased with SDS concentration increasing. This may be explained that the interfacial polymer concentration is so low that SDS molecules absorbed in the interface dominate dilational properties of the interfacial film even at very low SDS concentration. However, SDS molecules can gradually substitute the polymer molecules in the interface with a rise in SDS concentration, which results in the decrease in the limiting dilational elasticity.     

相转移催化合成对甲氧基肉桂酸-2-乙基己酯的研究

对甲氧基肉桂酸 2 乙基己酯是一种有效的ＵＶＢ防晒剂[1 ,2 ] ,一般采用Ｃｌａｉｓｅｎ Ｓｃｈｍｉｄｔ缩合反应制得[3] ,但由于催化剂ＫＯＨ处于水相 ,对反应物不能充分起到催化作用导致产率较低[4] 。我们利用乙二醇 (ＰＥＧ)为相转移催化剂合成立体专一的反式对甲氧基肉桂酸 2 乙基己酯 ,产率提高到 72 .5 %。合成路线如下 :1　实验部分1 .1　仪器与试剂ＢＩＯ ＲＡＰＦＴ45 0红外光谱仪 ,用液膜法测试 ;Ｂｒｕｒｅｒ ＡＭ 30 0超导核磁共振仪 (溶剂ＤＣ Ｃｌ3) ;ＭＡＴ/44Ｓ ,ＧＣ ＭＳ型色质联用谱仪 ;试剂均为分析纯 ,上海化学试剂…     

Resonance double light scattering method for the determination of proteins with morin-CTMAB

A new determination method of proteins with the limit of determination at nanogram levels is proposed by using a common spectrofluorimeter to detect intensity of resonance double line scattering (RDLS). Proteins including bovine serum albumin (BSA), human serum albumin (HSA) can combine with morin and cetyltrimethylammonium briomide (CTMAB) in the pH range 7.0-8.0 and produce enhanced RDLS signal at lambda(ex)/lambda(em) 305.0/610.0 nm. Optimization conditions for the morin-protein-CTMAB interaction were tested. In the studied system, BSA/CTMAB/morin = 1:2:3. The association constant of morin with BSA is 5.2 x 10(4). Under the optimum conditions, the linear range is 7.5 x 10(-8)-1.0 x 10(-5) g/ml for BSA, 2.5 x 10(-8)-5.0 x 10(-6) g/ml for HSA. The detection limits (S/N = 3) are 66.0 ng/ml for BSA and 23.0 ng/ml for HSA, respectively. Four synthetic samples were analyzed satisfactorily.     

羟基取代烷基苯磺酸盐界面扩张粘弹性质

研究了2-羟基-3,5-二癸基苯磺酸钠(C10C10OHphSO3Na)表面和正癸烷-水界面上的扩张粘弹性质, 考察了平衡时间对界面性质的影响. 研究结果表明, 羟基取代烷基苯磺酸钠具有十分特异的界面性质, 其扩张模量比一般表面活性剂大一个数量级, 达到平衡的时间较长, 形成的界面膜弹性较大. 界面张力弛豫测定结果表明, 平衡时界面上存在特征时间长达103 s的慢过程. 上述实验结果可能是由于羟基间形成氢键造成的.     

New bioactive triterpenoid from Oldenlandia cantonensis How

A new pentacyclic triterpenoid, urs-12-en-29α-oic acid-3β-ol (1), was obtained from the ethanol extract of Chinese herb Oldenlandia cantonensis How. The structure was elucidated by spectroscopy methods, including nuclear magnetic resonance (NMR) (1D and 2D), infrared spectroscopy (IR), and mass spectrometry (MS). 1 exhibited significant inhibitory activity against the human DNA topoisomerase I (hTopo I), the cancer cell lines BEL-7402 and MCG-803, with the IC₅₀ values 12.0, 6.5, and 8.0 μg/mL, respectively. The volatile oil, the fraction of petroleum ether: EtOAc = 20:1 (V/V) on Si gel chromatography, was also quantitatively analyzed by gas chromatography mass spectrometry (GC-MS). As a result, 60 compounds were identified. Among them, the long chain aliphatics, terpenes and steroids, as the representative structure type, were found with percentages of 36.16%, 6.42% and 9.28%, respectively. Translated from Chinese Journal of Applied Chemistry, 2006, 23(8): 871–874 [译自: 应用化学]     

Supercritical fluid extraction of flumetralin in tobacco

Summary This work evaluates the level of Flumetralin residues in real tobacco samples. Conventional extraction methods were compared with SFE methods in both static and dynamic modes using CO₂ and CO₂ with modifier. Additionally, in the dynamic SFE mode, different collection approaches, such as collection at room temperature without solvent, collection at room temperature in the presence of solvent (hexane) and collection in an ice bath, without solvent, were studied. SFE showed itself to be a promising extraction technique for pesticide residues in tobacco samples.