青蒿内酯的结构

从青蒿(Artemisia annua L.)中除了分得抗疟有效成分——青蒿素外,还分得多种倍半萜化合物如青蒿甲素、青蒿丙素、青蒿酸、青蒿醇、青蒿酸甲酯、青蒿内酯V、青蒿内酯VI.我们从青蒿乙醇提取物的石油醚溶解部位,经硅胶柱层析,首次从天然界中分得一个微量倍半萜内酯——青蒿内酯(artemisilactone).该化合物曾在青蒿酸结构测定时,由青蒿酸经过氧化氢氧化制得,但结构及立体结构未阐明,本文报道其立体结构的测定.     

青蒿素及其一类物结构和合成的研究——Ⅺ.环氧青蒿酸的分离和鉴定

青蒿亦称黄花蒿(Artemisia annua L.),为菊科植物,我国民间用于治疗疟疾。据报道,该植物的主要成分为挥发油、烯炔和倍半萜内酯。倍半萜内酯有青蒿素、青蒿甲素、青蒿乙素及青蒿丙素(脱氧青蒿素)。此外,还有青蒿酸、香豆素及黄酮等。我们由山东七、八月所产青蒿提取物中分到青蒿素、青蒿甲素、青蒿乙素、青蒿丙     

青蒿化学成分的研究Ⅰ.11R-(-)-双氢青蒿酸的分离和结构鉴定

中药青蒿的化学成分如挥发油、烯炔、香豆素、黄酮和倍半萜类化合物等已有文献报道,其中青蒿酸(1)可能是青蒿素的生物合成前体。从青蒿提取青蒿酸后,在母液中我们分离到1lR-(-)-双氢青蒿酸(2),它可能是青蒿酸转化为青蒿素的一个中间体。本文主要报告它的分离和结构鉴定。从青蒿中提取青蒿酸已有报道,我们改用碱提取法,较简便地分离得到青蒿酸。青蒿酸的结晶原母液用重氮甲烷甲酯化,产物用制备性薄层层析分离得青蒿酸甲酯(3)及另一组     

青蒿素及其一类物的结构和合成 XXI: 青蒿酸的全合成

青蒿酸与抗疟新药青蒿素共存于植物青蒿中, 具有显著的抗菌活性, 它的结构和立体化学已经确定, 并被用作合成青蒿素及其一类物的原料, 本文报导以R-(+)-香草醛为原料合成青蒿酸。     

青蒿挥发油化学成分的分析测定

青蒿[1]Artemisia annua L.又名香蒿,为菊科植物青蒿或黄花蒿的全草.分布辽宁、河北、山东、山西、江苏、广东等地.青蒿在我国各地均有大量野生,资源丰富,本植物的根(青蒿根),果实(青蒿籽)均可供药用,青蒿具有抗疟、抗血吸虫、解热、镇痛及退虚热、和胃止痛等功效.青蒿的主要成分有苦味质、挥发油和青蒿碱、维生素A等.为探讨其挥发油的成分,我们对青蒿全草进行挥发油的提取,并用GC-MS进行测定分析,从中鉴定出44个化合物.     

青蒿素生物合成的研究III: 青蒿素和青蒿素B生物合成中的关键性中间体-青蒿素

以[15-^3H]青蒿酸为前体用青蒿匀聚浆体进行青蒿素和青蒿素B的生物合成.实验结果表明, 在青蒿植物由MVA生物合成青蒿素和青蒿素B的途径中, 青蒿酸是关键性中间体.     

青蒿素生物合成的研究II. 前体[15-^2H]-和[15-^3H]-青蒿酸的 化学合成

青蒿酸甲酯(5)用NBS溴化产生的溴化物,经NaBD~3CN或NaBD~4氘解,生成[15-^2H]-青蒿酸甲酯(6),其结构由MS,^1H,^2H和^1^3C的NMR确定。(6)经水解生成[15-^2H]-青蒿酸(4),用同样方法以NaB^3H~4为氘化试剂与溴化物反应,合成了[15-^3H]-青蒿酸(1)。     

青蒿素生物合成的研究II. 前体[15-^2H]-和[15-^3H]-青蒿酸的 化学合成

青蒿酸甲酯(5)用NBS溴化产生的溴化物,经NaBD~3CN或NaBD~4氘解,生成[15-^2H]-青蒿酸甲酯(6),其结构由MS,^1H,^2H和^1^3C的NMR确定。(6)经水解生成[15-^2H]-青蒿酸(4),用同样方法以NaB^3H~4为氘化试剂与溴化物反应,合成了[15-^3H]-青蒿酸(1)。     

青蒿砜—氨基二硫代甲酸酯类化合物的合成

以双氢青蒿素(DHA)为原料,与草酰氯发生酰化反应,然后经硫代吗啉取代反应、双氧水氧化反应得到青蒿砜1,由1经过烷基化反应、脱硅保护基和碘代反应得到青蒿砜-碘代物2α;以三乙胺为催化剂,2α与哌嗪类化合物、CS_2在"一锅煮"条件下得到青蒿砜-氨基二硫代甲酸酯化合物(3a~3d)。所有目标化合物的结构均经~1H NMR、~(13)C NMR、IR和HR-ESI-MS得到确证。     

青蒿素及其一类物的结构和合成XVI.青蒿戊素的合成和α-环氧青蒿酸甲酯环氧的开环反应

β-环氧青蒿酸甲酯(25)经甲酸处理得反式双竖键开环产物(26),经水解和内酯化得青蒿戊素(1),α-环氧青蒿酸甲酯(5)或叔丁酯(18)及α-环氧双氢青蒿酸甲酯(12a,b)与甲酸反应未生成反式双竖键开环产物,并对其反应机理作了讨论。     

HPLC Fingerprint Characteristics of Active Materials of Garlic and Other Allium Species

The bioactive molecules of garlic are classified according to their enzymatic activities as either alliinase activators or alliinase inactivators. The alliinase activation reaction system is mainly composed of sulfur-containing compounds, whereas the alliinase inactivation system is mainly composed of amino acid-based materials. The purpose of this study was to develop an effective way to digitally express features of complex active compounds of garlic as a basis for quality control. HPLC was used to develop the fingerprints of plants from different Allium species and different geographical regions according to whether the compounds were sulfur containing or based on amino acids. Using the Shannon equation, I values of sulfur-containing compounds from garlic ranged from 3.55 to 3.94, whereas I values of sulfur-containing compounds from other Allium plants, onions, leek, and Welsh onion, ranged from 3.38 to 3.53. The I values of amino acid-based compounds from garlic ranged from 3.67 to 3.91, whereas I values of these compounds from other Allium plants ranged from 3.88 to 3.99. This method effectively distinguished garlic from different species of Allium plants. This method also provided a way to digitally monitor the presence of complex active compounds of garlic and may allow evaluation of quality. This method may also provide a theoretical basis for quality control of bioactive compounds from other medicinal plants.     

ESR studies of aqueous suspensions of zinc oxide

Results are presented from a technique which allows reproducible ESR spectra to be obtained from circulating aqueous suspensions of various zinc oxides. Singlet ESR signals with g ≈ 1.96 were observed in the dark from In-ZnO and from several zinc oxides under UV illumination. Fast and slow components of the photoinduced ESR signal are attributed respectively to surface and bulk electrons produced initially from photogenerated electron—hole pairs.     

Reaction Kinetics of the Hydrothermal Treatment of Lignin

Lignins derived from abundant and renewable resources are nontoxic and extremely versatile in performance, qualities that have made them increasingly important in many industrial applications. We have shown recently that liquefaction of lignin extracted from aspen wood resulted in a 90% yield of liquid. In this paper, the hydrothermal treatment of five types of lignin and biomass residues was studied: Kraft pine lignin provided by MeadWestvaco, Kraft pine lignin from Sigma-Aldrich, organosolv lignin extracted from oat hull, the residues of mixed southern hardwoods, and switchgrass after hydrolysis. The yields were found dependent on the composition or structure of the raw materials, which may result from different pretreatment processes. We propose a kinetic model to describe the hydrothermal treatment of Kraft pine lignin and compare it with another model from the literature. The kinetic parameters of the presented model were estimated, including the reaction constants, the pre-exponential factor, and the activation energy of the Arrhenius equations. Results show that the presented model is well in agreement with the experiments.     

尿液中纳米微晶的团聚促进泌尿系结石的形成

采用纳米粒度仪和透射电子显微镜(TEM)比较研究了尿石症患者与健康对照者尿液中纳米微晶的尺寸、粒度分布、聚集状态、自相关函数和ξ电位随放置时间的变化. 患者尿样放置3 h后, 其尿微晶平均粒径(D_a)由506 nm增至958 nm, 粒度分布范围变宽, 自相关时间由1.84 s延长到3.93 s, ξ电位由-1.34 mV降低至-3.89 mV; 而健康对照者尿微晶的D_a仅由330 nm增加至416 nm, 自相关时间由1.44 s延长至2.10 s, ξ电位由-8.35 mV降低至-8.90 mV. 此结果表明, 尿石症患者和健康对照者尿液中的纳米微晶不但在尺寸、粒度分布、聚集、自相关函数和ξ电位等方面存在明显的差异, 而且患者尿微晶的稳定性比对照者的差; 随着时间的延长, 患者尿液中的纳米微晶会逐渐团聚, 而对照者尿微晶的团聚要轻微得多. 从两类尿液中尿大分子和小分子抑制剂的浓度、尿微晶表面形成双电层的稳定性等方面进行了分析, 结果表明, 尿微晶的聚集是泌尿系结石生长的关键因素.     

Diagnostic value of different antigenic fractions of hydatid cyst fluid from camel and sheep in Kingdom of Saudi Arabia

Hydatid cyst fluids (HCF) crude extracts from camels and sheep slaughtered in Riyadh region, KSA were subjected to Sodium Dodecyl Sulfate–Polyacrylamide Gel Electrophoresis (SDS–PAGE) and Western blot analysis. Sera from 17 confirmed human cases of hydatidosis, 25 patients with other parasitic infections and 10 clinically healthy subjects were used to evaluate the diagnostic value of the different antigenic fractions of these extracts. Immunoblotting results revealed that, at least 11 major discrete protein fractions (110–8 kDa) were recognized by sera from hydatidosis patients, sera from patients with other parasitic diseases showed cross-reactivity with few of these bands. The cluster of bands (38–35 kDa) that may be a breakdown of “Arc 5” antigen (39–38 kDa) was detected by 100% and 94% of sera from hydatidosis cases with HCF extracts from camel and sheep, respectively. This cluster showed also some cross reactivity (20% and 8%) with control sera from patients with other parasitic infections with camel and sheep HCF extracts, respectively. Polypeptides at 24–22, 16 and 8 kDa which may probably correspond to antigen B subunits were also identified by all samples from hydatidosis patients with sheep HCF extracts and by 100%, 65% and 74% with camel HCF extracts respectively. Sera from control subjects did not react with any of these polypeptides (24–22, 16 and 8 kDa). According to our results, the identified molecular weight bands (16 and 8 kDa using HCF crude extracts from sheep and 24–22 kDa using HCF crude extracts either from camel or sheep) represent good candidates for immunodiagnosis of hydatidosis.     

Evolution of emission manners of organic light-emitting diodes: From emission of singlet exciton to emission of doublet exciton

The emission manners of organic light-emitting diodes(OLEDs) have experienced almost three-decade evolution.In this review,we briefly summarized the emission manners of OLEDs including:(ⅰ) emission from singlet exciton;(ⅱ) emission from triplet exciton;(ⅲ) emission from singlet exciton converted from triplet exciton.Then we introduced a new type of OLEDs with the emission from doublet exciton,wherein organic neutral radicals are used as emitters.Due to the spin-allowed transition of doublet excitons,using neutral radicals as emitters is believed to be a new way to break the 25%upper limit of internal quantum efficiency of OLEDs.The progress of emissive stable neutral radicals is also shortly reviewed.     

Comparison of calculated and experimental flow velocities upstream from the sampling cone of an inductively coupled plasma mass spectrometer

Experimentally-determined flow velocities in the 6 mm upstream from the sampling cone of an inductively coupled plasma mass spectrometer were compared with velocities determined from a computer simulation of the flow and those calculated from a modified hemispherical sink model. The measured values and those from the simulation agreed within experimental error, but differed from the values calculated from the modified hemispherical sink model by as much as 30%. An empirical alternative to the modified hemispherical sink model is presented that allows for accurate calculation of flow properties upstream from the sampling cone under a range of plasma conditions.     

Kinetic studies of oxidation of residual carbon from moroccan oil shale kerogens

Residual carbons from kerogen extracted from two Moroccan oil shales (from Timahdit and Tarfaya) were oxidized in air. The oxidations were studied by isothermal thermogravimetry. Several kinetic models for mechanisms of the reactions were tested to fit the experimental data. Oxidation of the residual carbon derived from Timahdit oil shale followed a two-third order reaction with an activation energy of 58.5 kJ mol^–1, whilst that from Tarfaya oil shale was a half order reaction with activation energy of 64.1 kJ mol^–1.     

Polymers for the Extraction of Chromium—Role of Polymers in the Removal and Recovery of Chromium from Wastewater

The present review discusses different possible routes of removal and recovery of chromium from industry and laboratory wastewater with special emphasis on the role of polymers in this context. Polymers can play a vital role in the easy, rapid and cost effective separation of chromium from aqueous solutions. Such studies of separation are important from the standpoint of identifying selective hosts and extractors for chromium. The use of suitable polymers in the removal and recovery of chromium from solutions is discussed.     

Contribution to the study of the mechanism of curing of unsaturated polyester resins

The mechanism of copolymerization of monomethyl and dimethyl maleates and fumarates with styrene was studied by analysis of the conformation of the acid units of the resulting copolymers. The absorption bands for C?O stretching and OH stretching in the spectra of the copolymers are fully identical. They are quite different from the spectra of the copolymers obtained from maleic anhydride and styrene that are subsequently treated with absolute methanol to give the monoester which is then esterified with diazomethane to give the diester. The acid units of the copolymers derived from maleic anhydride exist in a gauche configuration; copolymers derived from fumaric units exist in a trans conformation. The identity of copolymers derived from maleic units with those derived from fumaric units but not with those derived from maleic anhydride indicates that the first step in the copolymerization of the maleic units is an isomerization to fumaric units, which are actually the genuine comonomers.