pH区带逆流色谱法分离纯化马钱子中马钱子碱和士的宁

建立了pH区带逆流色谱分离制备马钱子中生物碱类成分马钱子碱和士的宁的方法。溶剂系统为V(甲基叔丁基醚):V(乙腈):V(水)=2:2:3,静置分层后,上相加入三乙胺,使其浓度为10mmol/L,作为固定相;下相加入HCl,使其浓度为10mmol/L,作为流动相。从308mg马钱子总生物碱中分离得到50mg马钱子碱和120mg士的宁,得率分别为72.8%和85.1%;纯度分别为96.8%和98.3%。并采用LC-ESI-MS和13CNMR对目标化合物的结构进行了鉴定。     

马钱子与甘草配伍前后生物碱成分的变化规律

采用电喷雾质谱技术和高效液相色谱法分别对马钱子配伍甘草前后主要生物碱的变化规律进行了系统研究。实验结果表明,马钱子配伍甘草后其主要生物碱士的宁和马钱子碱的含量均有不同程度的降低,其中士的宁的含量下降显著。电喷雾质谱的实验结果与高效液相色谱的结果相吻合,为进一步阐明甘草解马钱子类药物毒性和马钱子合理配伍用药提供了科学的实验依据。     

士的宁、马钱子碱的液质联用检验及应用

士的宁(Strychnine)又称番木鳖碱,与马钱子碱(Brucine)共存于马钱属的许多植物中,两者均有药用价值,常因误服过量或应用不当而引起中毒.     

HPLC分离化学发光检测药物中的马钱子碱、士的宁和麻黄类生物碱

在KMnO₄-H⁺-还原剂体系中研究了马钱子碱、士的宁和麻黄类生物碱的化学发光(CL)行为,建立了其快速灵敏的流动注射化学发光分析方法,将此法与HPLC联用,实现了上述物质的选择性测定,该方法的检出限为1.0×10^-10g/mL马钱子碱、1.0×10^-8g/mL士的宁、1.0×10^-5g/mL麻黄碱和伪麻黄碱,测定的相对标准偏差小于3%,HPLC流动相的脉动及其中的溶解氧不影响测定的精密度。此法已用于一些药物中马钱子碱等生物碱的测定,回收率为94%～101%.     

液相色谱-电喷雾串联质谱同时检测血液中8种有毒生物碱

建立了高效液相色谱-电喷雾串联质谱同时检测血液中8种有毒生物碱的方法.血液样品经过乙酸铵-氨水缓冲溶液(pH≈9)处理后,以甲醇提取,采用电喷雾电离(ESI)、多反应监测(MRM)方式,可同时对麻黄碱、毛果芸香碱、士的宁、阿托品、钩吻素子、马钱子碱、乌头碱、喜树碱8种有毒生物碱进行定性和定量分析.在优化的条件下,上述前4种组分在1～100 μg/L范围内线性关系良好,后4种组分在2.5～500 μg/L范围内线性关系良好.8种有毒生物碱的提取回收率在83.1%～104.0%范围内.士的宁、阿托品、马钱子碱、乌头碱和钩吻素子检出限为0.05 μg/L,定量限为0.1 μg/L;麻黄碱、毛果芸香碱、喜树碱的检出限为0.1 μg/L,定量限为0.5 μg/L.各组分的日内RSD小于9%,日间RSD小于10%.本方法操作简便快捷、选择性好、灵敏度高,适用于中毒诊断和法医毒物分析.     

马钱子中两种微量生物碱异构体的电喷雾多级串联质谱分析

采用电喷雾多级串联质谱方法, 通过分子量和多级串联质谱的信息对马钱子总生物碱提取物中微量生物碱异构体伪士的宁、士的宁氮氧化物进行了分析研究; 并研究了异构体质谱碎裂规律与结构之间的关系. 建立了马钱子中生物碱同分异构体区分的简便、快速、灵敏的新方法.     

毛细管电泳电化学检测法测定马钱子中的士的宁和马钱子碱

用毛细管电泳电化学检测法测定了马钱子中的士的宁和马钱子碱.以BR缓冲溶液(35 mmol/L混酸用180 mmol/L NaOH调节至pH 6.50)为电泳液,分离电压为6 kV,检测电位为0.95 V,士的宁和马钱子碱在30 min内得到了良好分离.士的宁和马钱子碱浓度分别在0.35～35.00 μg/mL和0.40(40.00 μg/mL内具有良好的线性关系,检测限分别为0.08μg/mL和0.15μg/mL.应用于马钱子样品的测定.     

士的宁分子印迹整体柱的制备

以士的宁为模板分子，甲基丙烯酸为功能单体，乙二醇二甲基丙烯酸酯作为交联剂，甲苯和十二醇混合溶液为致孔剂，用原位分子印迹技术，合成了士的宁分子印迹整体柱。通过优化合成条件，结果显示：模板分子、功能单体与交联剂之间的比例以1：4：16最佳，致孔剂中甲苯的最佳含量为18％（V/V)；对士的宁整体柱的色谱条件包括流动相组成、流速、柱温等进行了考察，并用于士的宁和马钱子碱的分离，其分离因子为3．5。     

在线固相萃取-高效液相色谱法同时测定人尿液中的马钱子碱和士的宁

建立了全自动、快速的在线固相萃取-液相色谱技术用于测定人尿液中的马钱子碱和士的宁的方法。样品离心后直接进样,其中被测组分富集于Hyper Sep Retain MCX柱上,尿液中的大分子基质物质不被保留而排出,在线完成萃取和净化富集过程;再通过阀切换使待测物转移至分析流路,在Acclaim C_(18)色谱柱上分离检测。分析时间约13 min。在线固相萃取流路以0.1%H_3PO_4和乙腈为流动相,1 m L/min流速萃取和洗脱;分析流路以乙腈和0.02 mol/L KH_2PO_4为流动相,1 m L/min流速等度洗脱,检测波长为260 nm。马钱子碱在1.25×10~(-6)~2.5×10~(-4)mol/L浓度范围内相关系数r为0.9930,高、中、低浓度的平均回收率分别为85.7%,81.4%和80.9%;士的宁在2.9×10~(-6)~2.9×10~(-4)mol/L浓度范围内相关系数r为0.9993,高、中、低浓度的平均回收率分别为87.1%,82.4%和78.9%。本法可用于测定人尿液中的马钱子碱和士的宁含量。     

气相色谱-串联质谱法同时检测尿液中15种有毒生物碱

在气相色谱-串联质谱(GC-MS/MS)多反应监测(MRM)模式下,建立了对尿液中八角枫碱、芦竹碱、毒扁豆碱、毛果芸香碱、哈尔碱、氧化苦参碱、黄华碱、钩吻素子、钩吻碱、延胡索乙素、吴茱萸碱、血根碱、白屈菜红碱、士的宁和马钱子碱15种有毒生物碱的定性定量分析。对样品前处理、色谱、质谱条件进行了优化。在优化条件下,毒扁豆碱、哈尔碱、钩吻素子和士的宁在20~800μg/L范围内线性关系良好,其余生物碱在40~800μg/L范围内线性关系良好,相关系数均不小于0.993 2。在高、中、低3种加标水平下,除八角枫碱的平均回收率为60.0%~68.3%外,其余14种生物碱的平均回收率为81.9%~114.4%,各生物碱的相对标准偏差(RSD)不大于17.6%。方法的检出限(LOD)为4~20μg/L,定量下限(LOQ)为10~40μg/L。该方法操作简便、快捷、灵敏,适用于中毒患者尿液中有毒生物碱成分的检测。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.