微量量热法研究黄连中小檗碱类生物碱对金黄色葡萄球菌生长代谢的影响

采用微量量热法研究中药黄连中具有抑菌作用的3种小檗碱类生物碱成分对金黄色葡萄球菌生长代谢的影响．在不同给药条件下,以表达功率．时间曲线（热谱曲线）的特征参数生长速率常数k、半数抑菌浓度（IC50）、最大输出功率（Pmax）及达峰时间（tp）和总产热量（Qt）为指标,对3种小檗碱类生物碱成分抑制金黄色葡萄球菌生长代谢程度进行客观地量化评价．结果表明,k、Pmax和Qt均随3种小檗碱类生物碱成分浓度的增加而相应的减小;tp随3种小檗碱类生物碱成分浓度的增加而相应的延长;其IC50分别为小檗碱101．4μg／mL、巴马汀241．0μg／mL和药根碱792．3μg／mL,即抑菌活性大小顺序为小檗碱〉巴马汀〉药根碱．初步构效关系研究提示,位于苯环的C2、C3上的亚甲二氧基或甲氧基较羟基更有助于提高其抑菌活性．     

胶束薄层扫描法测定黄连及其制剂中的小檗碱、巴马汀和药根碱

以2％CPC-醋酸乙酯(9：1)胶束溶液为展开剂,在聚酰胺薄膜上成功地分离了小檗碱、巴马汀和药根碱。以345nm为测定波长,550nm为参比波长进行扫描测定,建立了一种新的同时测定黄连及其制剂中小檗碱、巴马汀和药根碱的胶束薄层扫描法。小檗碱、巴马汀和药根碱的线性范围分别为0．2—2．4、0．1—1．0和0．1—1．0μg;回收率分别为97．7％-99．4％、101．7％～102．6％和96．7％-97．8％;相对标准偏差分别为1．4％-1．7％、1．9％-2．7％和1．8％-2．2％。     

离子液体作为流动相添加剂高效液相色谱法同时测定黄连中5种生物碱

建立了高效液相色谱法(HPLC)同时测定黄连中5种生物碱含量的方法。黄连药材经甲醇超声提取后,用Spherigel C_(18)色谱柱(250×4.6 mm,5μm)进行HPLC测定,流动相为含有1-己基-3-甲基咪唑四氟硼酸盐添加剂的甲醇-水(25:75,V/V),流动相流速为1.0 m L/min,检测波长为345 nm,同时测定了黄连药材中药根碱、表小檗碱、黄连碱、巴马汀和小檗碱含量。在1~200μg/m L浓度范围内,5种生物碱的线性相关系数均大于0.9990,药根碱、表小檗碱、黄连碱、巴马汀和小檗碱的检测限(LOD)分别为0.19,0.13,0.11,0.18,0.15 mg/L。测定了3种不同产地的黄连生物碱的含量并进行加标回收,回收率在98%~102%之间。     

高效毛细管电泳测定黄连及成药中小檗碱型生物碱的含量

报道了黄连及成药中七种小檗碱型生物碱的高效毛细管电泳分离测定方法。缓冲液由６５％磷酸氢二钠（用磷酸调ｐＨ７．０）和１５％甲醇组成。方法具有良好的精密度、回收率及线性关系。并用此法定量测定了黄连及六种成药中三种生物碱（小檗碱、巴马汀、药根碱）的含量。     

毛细管电泳安培法检测黄连中的生物碱

本文建立了一种简单快速的毛细管电泳安培检测法分离检测黄连中的黄连碱、盐酸小檗碱、巴马汀、和药根碱.以150 μm的铂电极为工作电极,考察并优化了影响分离和检测的条件.在80 mmol/L磷酸盐缓冲液中添加50%甲醇(pH 6.0),分离电压15 kV,检测电位1.2 V (vs.Ag/AgCl)的条件下,黄连碱、盐酸小檗碱、巴马汀和药根碱在8min内获得良好分离.黄连碱、盐酸小檗碱、巴马汀和药根碱的峰电流面积和浓度分别在1.0×10-5～2.0×10-7,1.0×10-5 ～8.0×10-8 mol/L,1.0×10-5～1.0×10-7 mol/L和1.0×10-5～2.0×10-7mol/L范围内呈良好的线性关系.检出限(S/N=3)低达10-8mmol/L.方法应用于微波辅助溶剂提取黄连中生物碱的测定,回收率在97.0%～104%,RSDs≤3.8%,结果满意.     

微量热法研究黄连及其主要组分配伍的抑菌作用

基于微量热法,研究黄连、黄连的主要组分小檗碱、药根碱、巴马汀及其配伍模拟方的抑菌作用.以HPLC法测定黄连中小檗碱、药根碱和巴马汀的含量,并根据其含量比值配伍模拟方;微量热法测定黄连、小檗碱、药根碱、巴马汀及其模拟方对痢疾杆菌的生长代谢曲线,得出相应的热动力学参数,并进行对应分析.结果表明黄连、小檗碱、药根碱、巴马汀及其模拟方对痢疾杆菌的生长代谢均有不同程度的抑制作用,黄连作用最强,单体生物碱作用弱,配伍模拟方作用增强,但并未显现明显协同作用,黄连的抑菌作用可能为多种活性成分的综合作用.     

原小檗碱类生物碱与抗凋亡蛋白Bcl-2相互作用的光谱法研究

应用荧光光谱法研究三种原小檗碱类生物碱: 盐酸小檗碱(Berberine hydrochloride)、药根碱(Jatrorrhizine)和盐酸巴马汀(Palmatine hydrochloride)与抗凋亡蛋白Bcl-2之间的相互作用, 探讨了这三种生物碱对Bcl-2蛋白的荧光淬灭机理, 分别测定其结合常数和结合位点数. 实验结果表明, 盐酸小檗碱、药根碱和盐酸巴马汀等三种原小檗碱类生物碱都能够使Bcl-2蛋白的内源性荧光发生淬灭, 其荧光淬灭过程是静态淬灭过程. 通过比较三种生物碱与Bcl-2蛋白的相互作用, 发现随着分子柔性增强, 其与Bcl-2蛋白的结合能力增强. 因此, 增强生物碱的分子柔性有可能增强其靶向Bcl-2蛋白的能力.     

近红外漫反射光谱法测定黄连浸膏粉中生物碱含量

采用近红外漫反射光谱法对黄连浸膏粉中小檗碱、巴马亭、药根碱和总生物碱含量进行快速无损检测。以HPLC分析值作参比,采用偏最小二乘回归算法建立二阶导数光谱信息与各组分含量间的定量校正模型,并对未知样品中各组分含量进行预测。小檗碱、巴马亭、药根碱和总生物碱的预测均方差(RMSEP)分别为0．184、0．109、0．054和0．325;加样回收率分别为97．67％～99．59％、96．63％～100．70％、95．15％～101．15％和97．41％～99．89％,重现性实验相对标准偏差(RSD)分别为0．3％、0．6％、1．8％和0．3％。该方法结果准确可靠,重现性、稳定性均良好,适用于工业现场的原位和在线检测。     

基于表面静电排斥/反相混合模式色谱的黄连生物碱分析方法

建立了基于表面静电排斥/反相混合模式色谱的黄连生物碱分析方法。选用实验室自制的C18HCE柱,以乙腈和水为流动相,考察了甲酸、乙酸两种流动相添加剂及其在流动相中的体积分数对黄连生物碱的保留、峰形及选择性的影响。最终确定0.1%（v/v）乙酸作为添加剂能实现黄连生物碱的良好分离,结合质谱和文献对其主要色谱峰进行了识别,分别为黄连碱、表小檗碱、非洲防己碱、药根碱、小檗碱、巴马汀。参考2015版《中国药典》对黄连生物碱的含量测定方法,以盐酸小檗碱进行方法学考察,结果表明,在0.5~100 mg/L范围内线性关系良好,相关系数为0.9996,平均加标回收率为93.74%。利用所建立的方法测定了湖北和重庆两个产地不同批次的黄连样品中各生物碱的含量。该方法简便,重复性好,精密度高,可为其他碱性化合物的分离分析提供参考。     

毛细管电泳法测定白头翁汤中黄连和黄柏共煎生物碱的煎出量

 建立了利用毛细管电泳简便、准确地测定白头翁汤中黄连和黄柏共煎生物碱煎出量的方法。采用自组装毛细管电泳装置,采用75μmi.d.×50cm弹性石英毛细管,以0 05mol/LNa2B4O7 CH3OH(体积比为85∶15)溶液作缓冲液,运行电压为14kV,检测波长为232nm。另外,通过实验优化了提取溶剂中乙醇的含量。实验结果表明:以小檗碱、巴马汀提取量为指标,30%(体积分数)的乙醇水溶液是提取白头翁汤中黄连和黄柏共煎生物碱的最佳溶剂。小檗碱和巴马汀的质量浓度分别在15 0mg/L～65 0mg/L、12 5mg/L～50 0mg/L时与其峰面积有良好的线性关系;小檗碱的平均回收率不低于95%。     

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.