山楂叶总黄酮中α-葡萄糖苷酶抑制剂的超滤质谱筛选研究

In vitro α-glycosidase inhibition assays and Ultrafiltration LC-DAD-ESI-MSn were combined to screening α-glucosidase inhibitors from hawthorn leaves flavonoids extract. As a result, hawthorn leaves flavonoids extract showed strong α-glucosidase inhibitory activity, four compounds presented α-glucosidase inhibitory effects were observed and identified by LC-DAD-MSn, and further confirmed by high resolution SORI-CID FT ICR MS data.

Theoretical studies on electronic structures, spectra and charge transporting properties of a series of Pt((CN)-N-Lambda)(2) complexes

We report a quantum-chemical study of electronic, optical and charge transporting properties of four platinum (II) complexes, pt((CN)-N-Lambda)(2) ((CN)-N-Lambda=phenylpyridine or thiophenepyridine). The lowest-lying absorptions at 442, 440, 447 and 429 nm are all attributed to the mixed transition characters of metal-to-ligand charge transfer (MLCT) and ligand-centered (LC) pi - pi(*) transition. While, unexpectedly, the lowest-lying phosphorescent emissions at 663, 660, 675 and 742 nm are mainly from metal-to-ligand charge transfer ((MLCT)-M-3) ligand-centered (LC) pi ->pi* transition. Ionization potential (IP), electron affinities (EA) and reorganization energy P (lambda(hole/electron)) were obtained to evaluate the charge transfer and balance properties between hole and electron.

Identification of Phenylethanoid Glycosides in Plant Extract of Plantago asiatica L. by Liquid Chromatography-Electrospray Ionization Mass Spectrometry

The present work describes a liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method for rapid identification of phenylethanoid glycosides in plant extract from Plantago asiatica L. By using a binary mobile phase system consisting of 0.2% acetic acid and acetonitrile under gradient conditions, a good separation was achieved on a reversed-phase C-18 column. The [M-H](-) ions, the molecular weights, and the fragment ions of phenylethanoid glycosides were obtained in the negative ion mode using LC-ESI-MS. The identification of the phenylethanoid glycosides (peaks 1-3) in the extract of P. asiatica L. was based on matching their retention time, the detection of molecular ions, and the fragment ions obtained by collision-induced dissociation (CID) experiments with those of the authentic standards and data reported in the literature.

Analysis of Saponins from Leaves of Aralia elata by Liquid Chromatography and Multi-stage Tandem Mass Spectrometry

Four saponins were isolated from the leaves of Aralia elata, and established using NMR and other spectroscopic methods, as well as data reported in the literature. Three Aralia saponins from the leaves of Aralia elata sharing the same structures as those isolated from the root bark suggested that the leaves would be a good substitute for the root bark of Aralia elata. These four Aralia saponins were then extensively investigated using complementarily positive and negative electrospray ionization multistage tandem mass spectrometry (ESI-MSn). Two isomers of saponins with different sugar linkages were then successfully differentiated by positive ESI-MSn and verified with different retention times and the collision-induced dissociation (CID) spectra by LC-MS. A simple and effective LC-MS method was thus developed for the rapid identification and screening of these saponins in plant extracts from leaves of Aralia elata.

Tunable Multiresponsive Methacrylic Acid Based Inverse Opal Hydrogels Prepared by Controlling the Synthesis Conditions

Methacrylic acid based inverse opal hydrogels (MIOHs) have been prepared by controlling the synthesis conditions, including cross-linker content, solvent content, and water content in solvent mixtures to explore the effect of the synthesis conditions (especially solvent content and mixture) on the response performance. Various response events (pH, solvent, ionic strength, 1,4-phenylenediamine dihydrochloride (PDA) response) have been investigated. For pH, solvent response, the same response behaviors have been observed: both the increased solvent (only ethanol) content and the enhanced water content in solvent will lead to the reduced response level of MIOHs compared to that of the increased cross-linker content. However, two different kinds of response behaviors for ionic strength response have been found by adjusting the synthesis conditions. The kinetics of pH response shows characteristics of a diffusion-limited process, and the equilibrium response time is about 20 min, which cannot be reduced by changing the synthesis conditions.

Four New Lanthanide-Nitronyl Nitroxide (Ln(III)=Pr-III, Sm-III, Eu-III, Tm-III) Complexes and a Tb-III Complex Exhibiting Single-Molecule Magnet Behavior

Five new complexes based on rare-earth-radical [Ln(hfac)(3)(NIT-5-Br-3py)](2) (Ln=Pr (1), Sm (2), Eu (3), Tb (4), Tm (5); hfac = hexafluoroacetylacetonate; NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) have been synthesized and characterized by X-ray crystal diffraction. The single-crystal structures show that these complexes have similar structures, in which a NIT-5-Br-3py molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N-O group and nitrogen atom from the pyridine ring to form a four-spin system. Both static and dynamic magnetic properties were measured for complex 4, which exhibits single-molecule magnetism behavior.

A monometallic tri-spin single-molecule magnet based on rare earth radicals

A mononuclear tri-spin single-molecule magnet based on the rare earth radical [Tb(hfac)(3)(NITPhOEt)(2)] (NITPhOEt = 4'-ethoxy-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized, structurally characterized and the alternating current signals show a slow relaxation of magnetization and frequency-dependent signals.

不同时间内家兔尿液中乌头碱代谢产物的研究

首次采用LC/ESI-MSn方法对乌头碱灌胃给药后不同时间内家兔尿液中的乌头碱代谢产物进对比研究。经与空白尿样对照发现,在0~4h和4~8h两个时间段,家兔尿液中除乌头碱(AC)原形外,均含有相同的代谢产物,但相对含量差别很大。通过总离子流色谱图(TIC)可以发现3个主要代谢产物(M1,M2,M4)。分别测定了各代谢产物的准分子离子及其各级碎片离子,与AC在ESI-MSn条件下的质谱碎裂规律相比较,并参考AC体内代谢文献,推断尿液中的主要代谢产物M1为16-O-去甲基乌头碱;M2和M4的m/z均为616,为同分异构体,结构还需要进一步的确认。