定量核磁共振波谱法同时测定中药虎杖中白藜芦醇和虎杖苷的含量

建立了定量核磁共振波谱法同时测定虎杖中白藜芦醇和虎杖苷的方法。样品用80%乙醇和丙酮两次超声提取净化,再用定量核磁共振波谱法测定。考察了样品预处理和核磁共振实验条件对测定结果的影响,选择氘代二甲亚砜-重水(10∶1,V/V)为溶剂,用基准物质邻苯二甲酸氢钾标定的2,3,5-三碘苯甲酸为内标,选择脉冲延迟时间为5 s,采样次数为32次。定量峰为6.388~6.391(白藜芦醇:H-2,6,d,2H)和6.322~6.330(虎杖苷:H-4,t,1H)。结果表明,NMR测定的精密度均小于0.6%,线性相关系数(r)均大于0.999,白藜芦醇和虎杖苷的检出限分别为0.23和0.24 g/L,定量限分别为0.69和1.57 g/L,包括样品提取过程的回收率分别为97.7%~103.5%(RSD=2.4%)和94.5%~99.2%(RSD=1.6%),显示出定量核磁共振法在中药定量时的可靠性。实际测定4种虎杖饮片及配方颗粒样品中白藜芦醇和虎杖苷含量分别为3.57~5.69 mg/g和12.73~24.07 mg/g。     

分子印迹滤过型净化柱净化/分子荧光光谱法测定花生根中白藜芦醇

以白藜芦醇(RES)为模板分子,凹凸棒土(ATP)为载体,β-环糊精(β-CD)和甲基丙烯酸(MAA)为双功能单体,采用表面分子印迹技术制备了白藜芦醇分子印迹聚合物(MIPs)。将制得的分子印迹聚合物作为吸附剂填料,填充滤过型净化柱,用于富集净化花生根中的白藜芦醇,建立了分子印迹滤过型净化柱净化/分子荧光光谱测定花生根中白藜芦醇的新方法。在最优化条件下,分子印迹聚合物对RES具有良好的选择性,最大吸附容量可达12.78 mg/g,白藜芦醇在0.1~100μg/m L浓度范围内呈良好的线性关系(r=0.999 7),方法检出限为0.048μg/L,样品加标回收率为86.2%~102.1%,相对标准偏差(RSD)为3.5%~5.8%。该方法高效、快速、选择性好,可用于白藜芦醇的快速检测。     

液相色谱-串联质谱法同时测定血浆中白藜芦醇苷及其代谢产物

建立同时测定大鼠血浆中白藜芦醇苷及其代谢产物白藜芦醇的液相色谱-串联质谱方法。以Lichro-spher C18色谱柱为分析柱,乙腈-水为流动相,采用电喷雾离子源(ESI),以多反应监测(MRM)模式检测,内标法定量,用于定量分析的离子反应分别为m/z389/227(白藜芦醇苷)和m/z227/143(白藜芦醇)。血浆中的白藜芦醇苷及白藜芦醇用乙酸乙酯提取,N2吹干乙酸乙酯,残留物用甲醇溶解,注入LC/MS/MS系统进行检测。在选定的样品预处理、色谱及质谱条件下,白藜芦醇苷、白藜芦醇及内标物能够达到基线分离而且离子化效果好。用LC/MS/MS法检测大鼠血浆中的白藜芦醇苷及其代谢产物白藜芦醇,线性范围0.4~200μg/L,日内、日间精密度(RSD)均小于15%;检测血浆低、中、高3个浓度(1、20、100μg/L)白藜芦醇苷的回收率分别为106.2%、97.8%和91.6%;检测血浆低、中、高3个浓度(1、20、100μg/L)白藜芦醇的回收率分别为113.2%、103.6%和93.4%。本方法具有灵敏、准确、快速的特点,可用于白藜芦醇苷的药代动力学研究。     

高效液相色谱法测定虎杖中白藜芦醇、白藜芦醇苷和游离大黄素

用高效液相色谱法同时测定虎杖中白藜芦醇、白藜芦醇苷和游离大黄素含量.色谱柱为Waters Symmetry C18柱(3.9 mm×150 mm,5μm),流动相为0.015 mol-1 H3PO4-甲醇,流速为0.5 mL·min-1,检测波长为284nm.样品采用乙醇-水(1 1)溶液和乙酸乙酯提取.江西产虎杖样品中白藜芦醇、白藜芦醇苷和游离大黄素的回收率分别为97.9%,96.1%,95.6%,相对标准偏差小于5%.     

导数分光光度法同时测定复方药剂中黄芩苷、白藜芦醇的含量

采用一阶导数分光光度法测定黄芩苷、白藜芦醇二元混合物中各组分的含量。黄芩苷的测定波长为257.2nm,白藜芦醇的测定波长为277.9nm。黄芩苷和白藜芦醇的浓度在1.0～20.0mg/L范围内与一阶导数光谱吸光度呈良好的线性关系,相关系数r≥0.9997。黄芩苷和白藜芦醇的回收率分别为98.6%～102.4%和99.5%～102.2%,相对标准偏差分别为1.39%和1.03%(n=6)。     

高效液相色谱法测定进口葡萄酒中的白藜芦醇及其甙

采用高效液相色谱法测定进口葡萄酒中的白藜芦醇及其甙。葡萄酒样品经过C18固相萃取柱净化后,采用Agilent Eclipse XDB-C18色谱柱进行分离,以乙腈溶液为流动相进行梯度洗脱,采用光电二极管阵列检测器在288nm和306nm处进行检测。白藜芦醇及其甙的质量浓度在0.2~20mg·L-1范围内与其峰面积呈线性关系,反式白藜芦醇甙、反式白藜芦醇、顺式白藜芦醇甙和顺式白藜芦醇的测定下限分别为2.6,1.5,4.6,3.0ng。加标回收率在77.3%~104%之间,测定值的相对标准偏差在1.4%~8.3%之间。     

高效液相色谱-串联质谱法测定植物源食品中四溴菊酯

建立了测定8种植物源食品中四溴菊酯残留的高效液相色谱-串联质谱分析方法。样品以乙酸乙酯为提取剂,经浓缩、净化,用流动相定容,采用高效液相色谱分离,以串联质谱在多反应监测模式下测定。结果表明,四溴菊酯质量浓度在20～1000μg/L范围内线性良好,相关系数为0.9998;在0.01、0.02和0.1 mg/kg(粮谷类样品)和0.005、0.01和0.05 mg/kg(果蔬类样品)添加水平下的回收率为81.6%～92.1%,相对标准偏差为4.0%～13%,定量限为0.01 mg/kg(粮谷类样品)和0.005 mg/kg(果蔬类样品)。     

固相微萃取-气相色谱-质谱法测定橡胶密封圈中8种N-亚硝胺含量

采用固相微萃取-气相色谱-质谱法测定橡胶密封圈中8种N-亚硝胺的含量。按国家标准GB/T 24153-2009进行样品的预处理,然后用二乙烯基苯/聚二甲基硅氧烷萃取头,在30℃和800r·min~(-1)转速的条件下萃取45min。在气相色谱分离中用Agilent 1701色谱柱为固定相;在质谱测定中采用选择离子监测模式。8种N-亚硝胺的线性范围均为0.10~2.0mg·L~(-1),方法的检出限(3S/N)均为0.03mg·kg~(-1)。以空白样品为基体进行加标回收试验,回收率在73.0%~96.1%之间,测定值的相对标准偏差(n=6)在1.3%~9.7%之间。     

气相色谱-质谱法测定食品中2-(4-甲氧基苯氧基)-丙酸钠

采用气相色谱-质谱法测定食品中2-(4-甲氧基苯氧基)-丙酸钠的含量。食品样品用盐酸(1+1)溶液酸化后经乙酸乙酯提取,在气相色谱分离中用DB-FFAP石英毛细管色谱柱为固定相,在质谱分析中采用选择离子监测模式。2-(4-甲氧基苯氧基)-丙酸的线性范围为5.0~100mg·L~(-1),方法的测定下限(10S/N)为4mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为79.5%~92.2%,测定值的相对标准偏差(n=6)为3.2%~6.2%。     

高效液相色谱法同时测定纺织品中11种二苯甲酮类紫外吸收剂

剪碎后的纺织品样品0.500 0g经30mL甲醇于60℃超声提取30min,冷却至室温后,取上清液用0.45μm有机滤膜过滤,采用高效液相色谱法同时测定滤液中11种二苯甲酮类紫外吸收剂的含量。以xBridge shield RP C_(18)色谱柱(250mm×4.6mm,5μm)为分离柱,用0.1%(体积分数,下同)甲酸溶液和含0.1%甲酸的甲醇-异丙醇溶液(甲醇与异丙醇体积比为7∶3)以不同比例混合的溶液为流动相进行梯度洗脱,在检测波长280nm处进行测定。11种二苯甲酮类紫外吸收剂的质量浓度均在0.5～20.0mg·L~(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)为3～9mg·kg~(-1),测定下限(10S/N)为9～27mg·kg~(-1)。以空白样品为基体进行加标回收试验,所得回收率为87.6%～107%,测定值的相对标准偏差(n=6)为1.9%～8.3%。方法应用于33批次的防紫外线纺织产品样品的分析,4-羟基二苯甲酮在所有样品中均未检出,其他二苯甲酮类紫外吸收剂均在样品中有不同程度的检出,2-羟基-4-甲氧基二苯甲酮的检出率最高,达到了58%,质量分数在42～261mg·kg~(-1)之间。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.     

Copper-catalyzed multicomponent reactions of 2-iodoanilines,benzylamines, and elemental sulfur toward 2-arylbenzothiazoles

A relatively cheap copper salt-catalyzed, three-component approach providing 2-arylbenzothiazoles in good to excellent yields from readily available 2-iodoanilines, benzylamines, and sulfur powder is reported. This methodology allows preparation of various classes of 2-arylbenzothiazoles and provides a general, reliable approach.