Determination of cnidilin and its two metabolites in rat bile and stool after oral administration by HPLC/electrospray ionization tandem mass spectrometry

A simple, fast and sensitive method for the simultaneous determination of cnidilin and its two metabolites (M1 and M2) in rat bile and stool using HPLC coupled with electrospray ionization tandem mass spectrometry (HPLC‐ESI‐MS/MS) has been developed. The sample pretreatment was simple, because methanol was the only additive used for dilution of bile and ultrasound of stool. Pimpinellin was used as internal standard (IS). The separation was performed on a reverse phase C₁₈ column with gradient elution consisting of 0.5‰ aqueous formic acid and methanol (containing 0.5‰ formic acid). The detection was in the multiple‐reaction monitoring mode within 7 min. All the analytes were in accordance with the requirement of the validation of the method in vivo (linearity, precision, accuracy, limit of detection and limit of quantification). After oral administrating 24 mg/kg of the prototype drug cnidilin, M1 and M2 were determined in bile within 36 h, and in stool within 60 h. Cnidilin in bile was completely excreted in 24 h, and the main excretive amount of cnidilin was 80% in the first 6 h, but the drug recovery in bile within 24 h was <1.95%. In stool, the main excretive amount of cnidilin was 95.8% in the first 24 h, and the drug recovery within 48 h was lower than 1.48%. Copyright © 2012 John Wiley & Sons, Ltd.     

Fundamental and engineering thermal aspects of energy and environment

Journal of Thermal Analysis and Calorimetry -     

Synthesis and biological evaluation of 20-hydroxytriptonide and its analogues

20-Hydroxytriptonide was synthesized from readily accessible l-abietic acid in 22 linear steps, which features a Barton reaction carried out under air atmosphere to install the C20-hydroxy group. Meanwhile, we also synthesized (5R)-5-hydroxytriptolide's probable metabolite product. Preliminary structure–activity relationship studies revealed that C20-angular methyl group might play a key role in maintaining the electronic properties of the whole molecule, which was essential for retaining the cytotoxic activity and might easily and inevitably be affected by the introduction of a new group.     

酸性条件下正钛酸钛(IV)中心与过氧化氢反应机理的第一性原理研究

正钛酸钛(IV)中心与过氧化氢的溶液反应很早就已经开始被加以关注和研究, 因其在化学催化、分析化学以及精细陶瓷方面具有重要用途. 尽管如此, 其不同条件下的反应机理以及产物长期以来没有得到共识. 本文主要希望通过对特定条件下(pH<1), 对这一反应进行第一性计算研究. 其中计算主要采用B3LYP泛函和6-311G+(3df,2p)基组的组合, 对可能的反应路径进行分步以及总反应热的计算, 其结果(27 kJ/mol)与实验值较为接近. 通过仔细研究反应中分子轨道的变化, 指出成环反应和氢转移反应是整体反应的关键步骤, 采用单向连串反应假设对实验现象进行分析, 并决定其宏观反应动力学“准一级”的特征, 获得了对特定及一般实验条件下的结果的合理解释. 通过对这一反应机理的研究, 我们希望能够将其推广至其他过渡族金属中心与过氧化物结合的反应中, 得以指导高效环氧化催化剂及精细陶瓷的合成与制备.     

Determination of chain orientation in the monolayers of amino-acid-derived schiff base at the air-water interface using in situ infrared reflection absorption spectroscopy

The chain orientation in the monolayers of amino-acid-derived Schiff base, 4-(4-dodecyloxy)-2-hydroxybenzylideneamino)benzoic acid (DSA), at the air-water interface has been determined using infrared reflection absorption spectroscopy (IRRAS). On pure water, a condensed monolayer is formed with the long axes of Schiff base segments almost perpendicular to the water surface. In the presence of metal ions (Ca2+, Co2+, Zn2+, Ni2+, and Cu2+) in the subphase, the monolayer is expanded and the long axes of the Schiff base segments are inclined with respect to the monolayer normal depending on metal ion. The monolayer thickness, which is an important parameter for quantitative determination of orientation of hydrocarbon chains, is composed of alkyl chains and salicylideneaniline portions for the DSA monolayers. The effective thickness of the Schiff base portions is roughly estimated in the combination of the IRRAS results and surface pressure-area isotherms for computer simulation, since the only two observable p- and s-polarized reflectance-absorbance (RA) values can be obtained. The alkyl chains with almost all-trans conformations are oriented at an angle of about 10 degrees for H2O, 15 degrees for Ca2+, 30 degrees for Co2+, 35 degrees -40 degrees for Zn2+, and 35 degrees -40 degrees for Ni2+ with respect to the monolayer normal. The chain segments linked with gauche conformers in the case of Cu2+ are estimated to be 40 degrees -50 degrees away from the normal.     

Highly Uniform Alkali Doped Cobalt Oxide Derived from Anionic Metal-Organic Framework: Improving Activity and Water Tolerance for CO Oxidation

A sequence of alkali metal cation-exchanged Co metal-organic frameworks(Co-MOFs), therein after denoted as M@Co-MOF, M=Na⁺, K⁺, Rb⁺, and Cs⁺, was prepared and used as the precursors to obtain the corresponding alkali doped cobalt oxide(defined as M/Co₃O₄, M=Na⁺, K⁺, Rb⁺, and Cs⁺) through calcination under air atmosphere. The cobalt oxide modified by uniform alkali metals exhibited a significant promotion of catalytic activity for CO oxidation. The activity of M/Co₃O₄ decreased in the order of Cs⁺ > Na⁺ > K⁺ > Rb⁺. Experimental and theoretical results revealed that the anionic skeleton of Co-MOF could facilely adsorb alkali metal cations and play a crucial role in the formation of highly uniform alkali doped cobalt oxide. The further characterizations, such as temperature-programmed reduction of H₂(H₂-TPR), oxygen temperature-programmed desorption(O₂-TPD), X-ray photoelectron spectroscopy(XPS), and in situ diffuse reflectance infrared Fourier transform(DRIFT) spectra demonstrated that the enhanced catalytic activity is originated from the interfacial electron transfer as well as weakened the Co-O bond strength, which promoted oxygen desorption from Co₃O₄ and formation of cobalt species with the lower valence state. The Cs/Co₃O₄ catalyst was maintained for 60 h without deactivation and still showed a high activity in the presence of water.     

α-Linolenic Acid Suppresses Proliferation and Invasion in Osteosarcoma Cells via Inhibiting Fatty Acid Synthase

Fatty acid synthase (FASN) is highly expressed in multiple types of human cancers and is recognized as one of the targets for treating cancer metastasis. α-Linolenic acid is an omega-3 essential fatty acid and it possesses various biological activities. The present study was designed to reveal the effects of α-linolenic acid on osteosarcoma and to reveal whether the mechanism of α-linolenic acid in anticancer activity may be related to FASN inhibition. The cytotoxicity of α-linolenic acid was assessed in osteosarcoma MG63, 143B, and U2OS cells. Cell viability was detected by the MTT assay. The protein expression level was detected by western blotting. Flow cytometry, Annexin V/propidium iodide dual staining, and Hoechst 33258 staining were performed to assess the apoptotic effects. Wound healing assay was applied to detect the inhibitory effect of α-linolenic acid on osteosarcoma cells migration. The results showed that α-linolenic acid downregulated FASN expression. α-Linolenic acid inhibited osteosarcoma cell proliferation and migration in a dose-dependent manner. In addition, α-linolenic acid regulated endoplasmic reticulum transmembrane receptors and signal protein expression in osteosarcoma cells. The findings of the present study suggested that α-linolenic acid suppresses osteosarcoma cell proliferation and metastasis by inhibiting FASN expression, which provides a basis as a potential target for osteosarcoma treatment.