Preparative separation of flavone dimers from Dysosma versipellis by counter‐current chromatography: Trifluoroacetic acid as a solvent system modifier

The separation of natural products is grueling and time‐consuming work with repeated isolations needed to obtain purified compounds. However, using counter‐current chromatography, a unique liquid–liquid partition chromatography, constituents can usually be purified efficiently. During the separation of flavone dimers from Dysosma versipellis (Hance) by counter‐current chromatography, the separation resolution and sample loading was impeded by the emulsification of the sample. By screening, trifluoroacetic acid was selected as the solvent modifier to eliminate the emulsification. Then, a quaternary solvent system of hexane/ethyl acetate/methanol/water (4:6:5:5 v/v/v/v) with trifluoroacetic acid at a low concentration of 0.5% v/v was used to purify the components from D. versipellis. Compared to that without trifluoroacetic acid, the separation resolution as well as the sample loading both increased greatly. In addition, flavone dimers in low concentrations could be enriched and purified at high sample loading. As a result, five podophyllotoxins and 11 flavonoids were purified and characterized by interpretation of spectroscopic data, in which two of eight flavone dimers were new and a known flavone dimer was first separated from this species.     

Simultaneous determination of sesquiterpene lactones isoalantolactone and alantolactone isomers in rat plasma by liquid chromatography with tandem mass spectrometry: Application to a pharmacokinetic study

A selective, sensitive, and accurate LC–MS/MS method for the simultaneous determination of isoalantolactone and alantolactone in rat plasma has been developed using psoralen as the internal standard. LC–MS/MS analysis was carried out on a Triple Quadrupole mass spectrometer using positive ion ESI and the selected reaction monitoring mode. The assays were linear in the range of 7.5–750 ng/mL for isoalantolactone and 5.5–550 ng/mL for alantolactone. The average recoveries in plasma samples both were better than 85%. The intra‐ and inter‐day precision and accuracy values were found to be within the assay variability criteria limits according to the US FDA guidelines. The method was successfully applied to pharmacokinetic studies of the two structural isomers after an intravenous injection of Inula helenium formulation to rats.     

Screening of allergic components mediated by H1R in homoharringtonine injection through H1R/CMC‐HPLC/MS

It has been reported that the histamine H₁ receptor (H₁R) gene is up‐regulated in patients with allergic rhinitis and H₁R expression level strongly correlates with the severity of allergy symptoms. Drugs for therapy should avoid allergy symptoms, especially for patients with over‐expressed H₁R. Therefore, screening of the components which could induce H₁R activation is urgently needed for drug safety evaluation. Homoharringtonine injection is a preparation for acute nonlymphocytic leukemia, which is approved by China Food and Drug Administration (CFDA) and US Food and Drug Administration. However, severely adverse reactions often occur with intravenous injection of the preparation. In present study, an H₁R/CMC model was applied for capturing membrane retained components which could induce H₁R activation. Retention components were enriched and analyzed by H₁R/CMC‐HPLC/MS. Homoharringtonine was recognized, separated and identified in homoharringtonine injection. Ca²⁺ flux assay and p‐IP3R expression founded that homoharringtonine retained by the H₁R/CMC model increased phosphorylation of IP3R and promoted cytosolic free Ca²⁺ elevation in a dose‐dependent manner which further verified the activity of homoharringtonine in activating the H₁R. In conclusion, homoharringtonine was screened and identified as a potential allergic factor. This provides an indication that a patient with over‐expressed H₁R should be aware of possible allergic reaction when applying homoharringtonine injection. Copyright © 2014 John Wiley & Sons, Ltd.     

The pharmacokinetic study of sinomenine,paeoniflorin and paeonol in rats after oral administration of a herbal product Qingfu Guanjiesu capsule by HPLC

An accurate and reliable high‐performance liquid chromatography–diode array detector (HPLC‐DAD) method was developed and validated for determination of sinomenine (SI), paeoniflorin (PF) and paeonol (PA), which was further applied to assess the pharmacokinetics of SI, PF and PA in an anti‐arthritic herbal product, Qingfu Guanjieshu (QFGJS) capsule, in rats. Successful separation was achieved with a C₁₈ column and a mobile phase composed of acetonitrile and aqueous phase (containing 0.1% formic acid, adjusted with triethylamine to pH 3.5 ± 0.2). The method was validated with excellent precision, accuracy, recovery and stability in calibration ranges from 0.06 to 11.62 µg/mL for SI, from 0.09 to 35.70 µg/mL for PF, and from 0.15 to 4.53 µg/mL for PA (with r² > 0.999 for all three compounds). Our results showed that absorption of PF after administration of QFGJS was similar to that after oral administration of PF alone; the absorption of SI was decreased while the absorption of PA was increased after giving QFGJS orally compared with pure compounds. We may conclude that pharmacokinetic studies of complex herbal products are not only necessary but also feasible by using representative bioactive chemicals as indicators of establishing quality control standards and of determining pharmacokinetic behavior of herbal medicines. Copyright © 2014 John Wiley & Sons, Ltd.     

Stereoselective synthesis of (−)-synargentolide B

A convergent, enantioselective total synthesis of (?)-synargentolide-B has been accomplished from readily available l-arabinose and d-ethyl lactate by a 10-step sequence involving Still-Gennari olefination, one-pot acidic deprotection/lactonization and olefin cross-metathesis reaction as the key step.     

Investigation of potential toxic components based on the identification of Genkwa Flos chemical constituents and their metabolites by high‐performance liquid chromatography coupled with a Q Exactive high‐resolution benchtop quadrupole Orbitrap mass spectrometer

Genkwa Flos, a famous traditional Chinese medicine has been reported to have significant hepatotoxicity. A high‐throughput and reliable method was established to explore potential toxic components by high‐performance liquid chromatography coupled with a Q Exactive high‐performance benchtop quadrupole‐Orbitrap mass spectrometer. A total of 68 compounds including 22 chemical components and 46 metabolites were tentatively identified based on the accurately measured mass value, retention time, and fragmentation pattern. Besides, the metabolic pathways of main components in Genkwa Flos were also illustrated. The results indicated that hydroxylation, demethylation, methylation, glucuronidation, sulfation, cysteine conjugation, and glutathione conjugation participated in the metabolic reactions of Genkwa Flos. Moreover, 12 Genkwa Flos chemical components and 26 metabolites were detected in cell lysate, which were considered as the bound components to HL‐7702 cells. In view of cell affinity theory, these compounds were preliminarily deduced to be potential toxic ingredients for the hepatotoxicity induced by Genkwa Flos. The results demonstrated that the developed method was a very feasible and efficient approach for the components identification even in the complex matrix. In conclusion, this study will provide a deep insight into the toxic substances of Genkwa Flos and lay a chemical basis for in‐depth toxic studies on Genkwa Flos hepatotoxicity.     

Finding thet-join structure of graphs

t-joins are generalizations of postman tours, matchings, and paths;t-cuts contain planar multicommodity flows as a special case. In this paper we present a polynomial time combinatorial algorithm that determines a minimumt-join and a maximum packing oft-cuts and that ends up with a Gallai-Edmonds type structural decompostion of (G, t) pairs, independent of the running of the algorithm. It only uses simple combinatorial steps such as the symmetric difference of two sets of edges and does not use any shrinking operations.     

Infrapetiole Exploration of the Supraglottis for exposure of the Anterior Glottal Commissure

Chevalier Jackson championed rigid endoscopy of the upperaerodigestive tract and facilitated its development and popularity at the beginning of the 20th century. He realized that endoscopy and open surgery are inextricably linked for effective management of diseases of the upper air and food passages. Toward this end, Jackson contributed a number of important innovations to direct laryngoscopy, while developing a unique mastery of the technique. Ultimately, he combined this endoscopic proficiency with open surgical techniques.     

电感耦合等离子体原子发射光谱/质谱法在中药微量元素及形态分析中的应用

本文对近年来电感耦合等离子体原子发射光谱法（ICP－AES）和电感耦合等离子体质谱（ICP－MS）在中药微量元素及形态分析中的应用进行了评述，讨论了应用ICP－AES／MS技术测定中药微量元素样品处理和各种分析方法，引用文献58篇。微波消解可作为中药微量元素分析理想的样品处理方法；ICP－AES／MS及各种联用技术在中药微量元素含量及形态分析中将发挥越来越重要的作用。