党参花粉多糖的研究

从蜜峰采集的党参花粉中,分离到5种多糖CPA～CPE,经凝胶过滤及电泳法验证了纯度并测定了分子量。对CPA进行了全水解、甲基化分析、NalO_4氧化和Smith降解分析,用旋光法测定了CPA中单糖残基的绝对构型,对CPA的IR、~1H NMR、~(13)C NMR及~1H NMR、~(13)C偶合NMR进行了分析,确定了异头碳的构型。对CPA进行了电子显微镜分析,首次在透射电子显微镜下观察并拍摄到了具有串珠状特殊二级结构的多糖照片,经分析得到了CPA二级结构的一些信息。     

HPLC determination of four active saponins from Panax notoginseng in rat serum and its application to pharmacokinetic studies

Four main active saponins (ginsenosides Rg1, Rb1, Rd and notoginsenoside R1) in Panax notoginseng in rat serum after oral and intravenous administration of total saponins of P. notoginseng (PNS) to rats were determined using a simple and sensitive high-performance chromatographic method. The serum samples were pretreated with solid-phase extraction before analysis. The calibration curves for the four saponins were linear in the given concentration ranges. The intra-day and inter-day assay coefficients in serum were less than 10.0% and the recoveries of the method were higher than 80.0% in the high, middle and low concentrations. This method was applied to study the pharmacokinetics following oral and intravenous administration of PNS.     

聚醚桥连二异羟肟酸单核和双核过渡金属配合物催化PNPP水解

Two polyether bridged dihydroxamic acids and their mono-and binuclear manganese(Ⅱ), zinc(Ⅱ) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p-nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono-and binuclear metal, the pseudo-macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dthydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo-macrocyclic polyether might synergetically activate H20 coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.     

Photoredox‐Catalyzed Functionalization of Alkenes with Thiourea Dioxide: Construction of Alkyl Sulfones or Sulfonamides

Sulfonylation of alkenes through photoredox‐catalyzed functionalization of alkenes with thiourea dioxide under visible‐light irradiation is achieved. The reaction of alkenes, thiourea dioxide and electrophiles provides a green and efficient access to alkyl sulfones and sulfonamides. A broad reaction scope is presented with good functional group compatibility and excellent regioselectivity. A plausible mechanism involving a radical addition process with sulfur dioxide radical anion (SO₂^‐) derived from the oxidation of sulfur dioxide anion (SO₂^2–) is proposed, which is supported by fluorescence quenching experiments.     

A facile solid-phase synthesis of substituted 2(5H)-furanones from polymer-supported alpha-selenocarboxylic acids

The synthesis of polystyrene-supported alpha-selenoacetic acid, alpha-selenopropionic acid, and alpha-selenophenylacetic acid is described. The reaction of the dilithio derivatives of polymer-supported alpha-selenocarboxylic acids with racemic epoxides or optically active styrene oxide afforded polystyrene-supported gamma-substituted alpha-selenobutyrolactones. The alpha-alkylation reaction of gamma-substituted polystyrene-supported alpha-selenobutyrolactones provided another route for the synthesis of polystyrene-supported alpha,gamma-disubstituted alpha-selenobutyrolactones. Subsequent oxidation-elimination with an excess of 30% hydrogen peroxide at room temperature afforded substituted (3- and 5-mono-; 3,4- and 3,5-di) 2(5H)-furanones in high yields and good purities.     

Theoretical Studies on the Abstraction Reaction of Atomic O（^3p） with Si2H6

The hydrogen abstraction reaction of O(^3P) with Si2H6 has been studied theoretially. Two transition states of ^3A″ and ^3A′ symmetries have been located for this abstraction reaction. Geometries have been optimized at the UMP2 leve with 6-311G (d) basis set. G3MP2 has been used for the final single-point energy calculation. The rate constants have been calculated over a wide temperature range of 200-3000K using canonical variational transition-state sheory (CVT) with small curvature tunneling effect(SCT). The calculated CVT/SCT rate constants match well with the experimental value.     

Fullerenes-extracted soot: a new adsorbent for collecting volatile organic compounds in ambient air

Fullerenes-extracted soot (FES) is the by-product of fullerenes production. Retention characteristics at different temperatures for 17 volatile organic compounds (VOCs) on FES are measured. The adsorption and desorption efficiencies for VOCs on FES adsorbent tubes range from 40.8 to 117%, most of them being 100+/-20%. The values are compared with Tenax GR, an adsorbent commonly used in environmental analysis. FES can be used as an adsorbent of low cost to collect VOCs in environmental samples.     

Novel Sesquiterpenes from the Fungus Lactarius piperatus

Four novel sesquiterpenes, namely 7α,8β,13‐trihydroxy‐5,13‐marasmanolide ( 2 ), isoplorantinone ( 5 ), 4,8,14‐trihydroxyilludala‐2,6,8‐triene ( 6 ), and 8‐hydroxy‐8,9‐secolactara‐1,6‐dien‐5,13‐olide ( 10 ), together with six known ones, 7α,8β‐dihydroxy‐5,13‐marasmanolide ( 1) , 7α,8α‐dihydroxy‐5,13‐marasmanolide ( 3 ), isolactarorufin ( 4 ), blennin A ( 7 ), blennin D ( 8 ), and lactarorufin ( 9 ), were isolated from the ethanolic extract of Lactarius piperatus. The structures of these sesquiterpenes, representing diversified structural types, were determined mainly by spectroscopic methods, especially 2D‐NMR techniques. The structure of 6 was further confirmed by a single‐crystal X‐ray‐diffraction determination.     

A potent and highly selective sulfotransferase inhibitor

In the present work, we have used a newly developed, fluorescence-based assay to screen a library of >30 000 compounds as potential beta-arylsulfotransferase-IV inhibitors. A total of 11 inhibitors were discovered. Most of the compounds discovered showed low micromolar inhibition, but one of the compounds showed potent inhibition (Ki = 96 nM). The most potent of these inhibitors was tested against a variety of other purine binding enzymes and showed remarkable specificity.