LC–DAD–ESI-MS-MS for Characterization and Quantitative Analysis of Diterpenoids from Coleus forskohlii

Qualitative characterization and quantitative analysis of labdane diterpenoids from Coleus forskohlii have been achieved by liquid chromatography hyphenated with photodiode-array detection and tandem electrospray ionization mass spectrometry (LC–DAD–ESI-MSⁿ). By use of this method, thirteen forskolin-type diterpenoids were identified in the crude extract on the basis of their fragmentation mechanisms. Fragmentation rules were deduced from nine forskolin-type standards by ESI-MS in positive-ion mode. It was found that fragmentation behavior varied with the position and number of the substituents on the skeleton; this could be used for convenient identification of this type of compound. Six marker diterpenoids were also quantified, and the quality of both the cultivated and wild plants was evaluated.

     

β-环糊精包覆碳纳米管基质用于氨基酸及小分子聚合物的MALDI-FT MS研究

制备了可用作氨基酸及小分子聚合物的MALDI-FTMS分析基质的β-环糊精包覆多壁碳纳米管.通过引入β-环糊精改善其碳纳米管亲水性.所制备的β-环糊精包覆多壁碳纳米管的扫描电镜图表明,该碳纳米管呈现纳米带状结构.与通常的氧化碳纳米管相比,所制备的β-环糊精改性CNT具有更低的背景信号.进一步采用氨基酸及聚乙二醇等小分子化合物对所制备的碳纳米管进行评价,得到很强的氨基酸及聚乙二醇的碱金属离子加合峰,表明该材料可使小分子化合物解吸离子化,且背景干扰小不会影响到小分子化合物检测.由此可见,制备的β-环糊精包覆多壁碳纳米管适于小分子化合物的MALDI-MS分析.     

Reversal effects of traditional Chinese herbs on multidrug resistance in cancer cells

Multidrug resistance (MDR) continues to be a major obstacle for successful anticancer therapy. In this work, fractions from 17 clinically used antitumour traditional Chinese medicinal herbs were tested for their potential to restore the sensitivity of MCF-7/ADR and A549/Taxol cells to a known antineoplastic agent. The effects of these fractions were evaluated by MTT method and an assay of the cellular accumulation of doxorubicin. Fractions from the PB group (herbs with the ability to promote blood circulation and remove blood stasis) showed more significant effects than fractions from the CH group (herbs with the ability to clear away heat and toxic materials). Fractions from CH?Cl? extracts were more effective than fractions from EtOAc extracts. Five herbs (Curcuma wenyujin, Chrysanthemum indicum, Salvia chinensis, Ligusticum chuanxiong Hort. and Cassia tora L.) could sensitise these resistant cancer cells at a non-toxic concentration (10?μg?mL?1), and markedly increased doxorubicin accumulation in MCF-7/ADR cells, which necessitates further investigations on the active ingredients of these herbs and their underlying mechanisms.     

A Highly Selective Turn-On Fluorescent Probe for the Detection of Zinc

A novel turn-on fluorescence probe L has been designed that exhibits high selectivity and sensitivity with a detection limit of 9.53 × 10⁻⁸ mol/L for the quantification of Zn²⁺. ¹H-NMR spectroscopy and single crystal X-ray diffraction analysis revealed the unsymmetrical nature of the structure of the Schiff base probe L. An emission titration experiment in the presence of different molar fractions of Zn²⁺ was used to perform a Job’s plot analysis. The results showed that the stoichiometric ratio of the complex formed by L and Zn²⁺ was 1:1. Moreover, the molecular structure of the mononuclear Cu complex reveals one ligand L coordinates with one Cu atom in the asymmetric unit. On adding CuCl₂ to the ZnCl₂/L system, a Cu-Zn complex was formed and a strong quenching behavior was observed, which inferred that the Cu²⁺ displaced Zn²⁺ to coordinate with the imine nitrogen atoms and hydroxyl oxygen atoms of probe L.     

Novel rearranged acetophenone derivatives possessing diverse architectures from the leaves of Melicope ptelefolia

Melicolones C–K (1–9), nine acetophenone derivatives with three unprecedented architectures, were characterized from the leaves of Melicope ptelefolia. Among them, melicolone C (1) was a novel acetophenone analogue possessing a highly rearranged spiro skeleton. Melicolones D-F (2–4) were three novel acetophenone congeners bearing unusual octalactone ring. Melicolones G-K (5–9) were five new prenylated acetophenone derivatives featuring a 9-oxatricyclo [3.2.1.13, 8]nonane core. Their structures were established by extensive spectroscopic analysis and ECD spectra. These different structures were presumably derived from the same precursor via three major biosynthetic pathways. Compounds 5–9 exerted moderate effects to reverse multidrug-resistance in MCF-7/ADR cells with reversal fold values ranging from 6.2 to 13.3.     

金属有机物化学气相沉积法生长Ga2（1-x）In2xO3薄膜的结构及光电性能研究

采用金属有机物化学气相沉积（MOCVD）法在蓝宝石（0001）衬底上制备出了Ga_2（1-x）In_2xO₃（x=01—09）薄膜,研究了薄膜的结构、电学和光学特性以及退火处理对薄膜性质的影响.测量结果表明：当In组分x=02时,样品为单斜β-Ga₂O₃结构;x=05的样品,薄膜呈现非晶结构,退火处理后薄膜结构得到明显的改善 关键词： 金属有机物化学气相沉积 2（1-x）In_2xO₃薄膜')" href="#">Ga_2（1-x）In_2xO₃薄膜 蓝宝石衬底 退火     

金属有机物化学气相沉积法生长Ga2(1-χ)In2χO3薄膜的结构及光电性能研究

采用金属有机物化学气相沉积(MOCVD)法在蓝宝石(0001)衬底上制备出了Ga2(1-χ)In2χO3(χ=0.1-0.9)薄膜,研究了薄膜的结构、电学和光学特性以及退火处理对薄膜性质的影响.测量结果表明:当In组分χ=0.2时,样品为单斜β-Ga2O3,结构;χ=0.5的样品,薄膜呈现非晶结构,退火处理后薄膜结构得到明显的改善,由非晶结构转变为具有(222)单一取向的立方In2O3结构;对于χ=0.8,薄膜为立方In2O3,结构,退火后薄膜的晶体质量得到提高.在可见光区薄膜本身的透过率均达到了85%以上,带隙宽度随样品中Ga含量的改变在3.76-4.43 eV之间变化,且经退火处理后带隙宽度明显增大.     

Two new monodesmosidic triterpene saponins from Gypsophila oldhamiana

Two new monodesmosidic triterpene saponins were isolated from the roots of Gypsophila oldhamiana (Caryophyllaceae). Their structures were elucidated on the basis of spectral data to be quillaic acid, alpha-L-arabinopyranosyl-(1-->4)-alpha-L-arabinopyranosyl-(1-->3)-beta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranosyl ester (1), and vaccaric acid, beta-D-glucopyranosyl-(1-->3)-[beta-D-xylopyranosyl-(1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-fucopyranosyl ester (2). Compound 1 showed a significant enhancement of granulocyte phagocytosis in vitro.     

Aphanalides A–H,ring A-seco limonoids from the fruits of Aphanamixis polystachya

Eight new ring A-seco limonoids, aphanalides A–H (1–8) were isolated from the fruits of Aphanamixis polystachya. Aphanalides A–C (1–3) are the first examples of ring A-seco limonoids with an unusual oxetane ring between C-7 and C-14. The structures of aphanalide A (1) and aphanalide C (3) were confirmed by single-crystal X-ray studies. Their structures including absolute stereochemistry were established on the basis of extensive NMR spectroscopic analysis, by comparison of experimental and calculated electron circular dichroism (ECD) and by X-ray diffraction, representing the first report of assignment of absolute configuration of such type ring A-seco limonoids. The biogenetic origin of aphanalides A–D (1–4) from aphanalides E–H (5–8) was also postulated.     

Three new phenolic glucosides from the roots of Rheum palmatum

A novel naphthalene glucoside, rheumone A (1), with an unprecedented skeleton containing a seven-membered lactone, and two new compounds, 1-O-phloroglucinyl-2-O-galloyl-6-O-cinnamoyl-β-D-glucoside (2) and chrysophanol 1-O-β-D-(6'-O-malonyl)glucoside (3), together with three known compounds (4-6) were isolated from the roots of Rheum palmatum. Their structures were elucidated mainly by spectroscopic analysis. These compounds were evaluated in vitro for their cytotoxicities towards human hepatocellular cancer cell lines Bel-7402 and Bel-7402/5Fu, and human gastric carcinoma cell line BGC-823. None of them showed cytotoxicity with IC(50) far beyond 50 μM.