反相高效液相色谱同时测定五味子中五味子醇甲、五味子酯甲和五味子乙素的含量

本文建立了同时测定五味子中五味子醇甲、五味子酯甲和五味子乙素的反相高效液相色谱(RP-HPLC)方法。五味子先经超声提取后用高效液相色谱法测定。色谱柱为Kromasil C18柱(150×4.6 mm,5μm),流动相为甲醇-水(75∶25,V/V),紫外检测波长220 nm,柱温30℃,流速1.0 mL/min。结果显示,五味子醇甲在0.10~6.0μg范围内(r=0.9998),五味子酯甲在0.13~8.0μg范围内(r=0.9999),五味子乙素在0.03~2.0μg范围内(r=0.9999)线性关系良好。平均回收率五味子醇甲为98.6%,相对标准偏差(RSD)为1.4%(n=5);五味子酯甲为97.1%,RSD为1.6%(n=5);五味子乙素为97.7%,RSD为1.1%(n=5)。本法准确、快速、灵敏度高,可用于五味子中有效成分的定量分析。     

高效液相色谱法测定北五味子中5种木脂素含量

应用高效液相色谱法测定北五味子中五味子醇甲、五味子酯甲、五味子甲素、五味子乙素和五味子丙素等5种木脂素的含量。北五味子样品(1.000g)在70℃温度下用甲醇(20mL)微波辅助提取5min。分取部分提取液,以Hypersil ODS C18色谱柱为固定相,用乙腈和水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225nm处进行测定。5种木脂素在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.029 2~0.050 7mg·L-1之间。以样品为基体,在3个浓度水平加入混合标准溶液进行回收试验,测得回收率在95.3%~101%之间,测定值的相对标准偏差(n=6)在1.1%~2.4%之间。     

一测多评高效液相色谱法同时测定五味子中五味子醇甲、五味子甲素、五味子乙素

建立一测多评高效液相色谱法同时测定五味子中五味子醇甲、五味子甲素、五味子乙素含量的方法,并验证该法的可行性和准确度。通过Plackett-Burman设计考察流动相中甲醇比例、流动相流量、柱温、进样体积对五味子醇甲色谱峰分离度的影响,确定流动相中甲醇比例、柱温为关键分析参数（P<0.05）。通过中心组合设计优化关键分析参数,建立色谱分析条件：以甲醇-水（体积比为70∶30）溶液作为流动相进行洗脱,流量为1.0 mL/min,柱温为35℃,检测波长为254 nm,进样体积为10μL。以五味子醇甲为内参物,分别建立五味子甲素、五味子乙素与五味子醇甲的相对校正因子,计算各成分含量,实现一测多评。采用外标法测定五味子甲素、五味子乙素含量,比较外标法的实测值与一测多评法预测值之间的差异,以验证一测多评法的准确度及可行性。五味子中五味子醇甲与五味子甲素、五味子乙素的相对校正因子分别为1.039、1.246。五味子醇甲、五味子甲素、五味子乙素色谱峰面积与质量浓度在5～500μg/mL范围内呈良好的线性关系,相关系数均大于0.999。样品加标回收率分别为100.1%、100.6%、100.3%,...     

南北五味子醇提液的荧光光谱鉴别

建立了用荧光光谱法快速鉴别五味子和部分含五味子制剂中五味子药材种属的方法. 研究了五味子中的五味子醇甲、五味子酯甲、五味子甲素、五味子乙素和安五脂素5种活性成分以及南北五味子和护肝片的乙醇提取液的荧光光谱,并用高效液相色谱测定了供试品中5种活性成分的含量. 结果表明,安五脂素和五味子乙素具有强荧光性且峰形差异显著,五味子甲素和五味子醇甲的荧光性较弱,而五味子酯甲不具有荧光性;南北五味子的主要荧光物质分别为安五脂素和五味子乙素,据此可用乙醇提取液的荧光光谱快速鉴别南北五味子.     

三种五味子素荧光性质

研究了五味子甲素、五味子乙素和五味子酯甲的荧光性质,并对五味子酯甲分别在氢氧化钠和硫酸70℃条件下的水解产物用高效液相色谱法和荧光法进行了研究.试验结果表明:以250～260 nm波长的光作为激发光源,五味子甲素和五味子乙素发射光波长在350～360 nm之间,但五味子乙素的发光效率比五味子甲素强十几倍,而五味子酯甲不产生荧光,但五味子酯甲的水解产物能产生荧光,且发光效率与五味子乙素相似.     

五味子超临界CO2提取物的气相色谱-质谱分析

将五味子样品于25 MPa、45 ℃下用超临界CO2提取2 h,提取物经气相色谱-质谱分析,共测得16个成分,经与对照品、NIST谱库对照和结构解析,鉴定出其中的7种木脂素成分,占色谱峰总面积的80.5%,其中五味子甲素9.39%、五味子乙素30.58%、五味子醇甲16.00%、五味子丙素5.95%和五味子醇乙15.17%。     

南北五味子荧光光谱差异的原因

建立了用荧光法快速鉴别五味子和部分含五味子制剂中五味子是属于北五味子还是南五味子的方法,探明了南北五味子荧光光谱差异的主要原因。研究了五味子的五种活性成分五味子醇甲、五味子酯甲、五味子甲素、五味子乙素和安五脂素的荧光性质和五味子以及护肝片乙醇提取液的荧光光谱,并用高效液相色谱测定了供试品五种活性成分的含量。研究表明：发光效率按安五脂素、五味子乙素、五味子甲素和五味子醇甲依次减弱,五味子酯甲不具有荧光性;北五味子的主要荧光物质为五味子乙素,而南五味子的主要荧光物质是安五脂素,它们是导致南北五味子荧光光谱差异的主要原因。用荧光法鉴别南北五味子具有简单、快速和灵敏的特点     

超分子有序聚集凝固液相微萃取及其对五味子中木脂素类化合物的测定及质量评价

通过分析比较漂浮有机液滴凝固液相微萃取(SFODLPME)对木脂素类化合物萃取前后紫外光谱的变化, 提出了超分子有序聚集凝固液相微萃取(SSMOALPME)机理; 建立了简单、 快速、 灵敏的SSMOALPME高效液相色谱法(HPLC)同时测定中药五味子中5种低丰度木脂素类化合物含量的方法, 并对不同产地五味子的质量进行比较和评价. 在最佳的SSMOALPME条件下, 测得五味子醇甲, 五味子酯甲, 五味子甲素, 五味子乙素和五味子丙素的线性范围分别为2.48×10^-3~6.21, 2.27×10^-3~28.5, 2.31×10^-3~28.8, 2.27×10^-3~5.69和1.05×10^-3~5.25 μg/mL; 检出限分别为0.4, 0.4, 0.4, 0.08和0.08 ng/mL; 日内及日间精密度RSD<9.7%; 药材中分析物的回收率为91.9% ~104.7%; SSMOALPME对5种分析物的富集倍数分别在39 ~529倍之间. 本法测定结果与药典法测定结果相比无显著差异(P=95%). SSMOALPME方法的提出为液相微萃取的理论研究奠定了基础, 为反映中药多成分、 多靶点及协同作用的特性, 建立科学的质量控制方法提供了理论依据和实验基础.     

南五味子中五味子甲素的薄层扫描色谱定量分析

南五味子是2000年中国药典开始收录的中药材。南五味子与北五味子的性状完全不同,所含化学成分亦不同,功能主治各有侧重。南五味子为木兰科植物华中五味子的干燥成熟果实,性味酸、甘、温,具有收敛固涩,益气生津,补肾宁心之功效。现代研究表明,南五味子的活性成分主要包括五味子甲素和五味子酯甲等木脂素成分。五味子甲素具有显著的功效,但药典仅有五味子酯甲的含量测定,未有五味子甲素的含量测定,相关研究报道也很少,因此有必要研究建立南五味子中五味子甲素含量测定方法。     

高效液相色谱法测定五味子和含五味子的制剂中五味子乙素及多种活性成分时流动相体系的选择

建立了用高效液相色谱法测定五味子和含五味子的制剂中五味子乙素的流动相体系。用Shim-pack VP-ODS (250 mm×4.6 mm,5 μm)色谱柱,在柱温30 ℃、检测波长285 nm、流速1.0 mL/min的条件下,用不同的流动相组成及其不同比例研究了五味子提取液中3种木脂素(五味子乙素、安五脂素和五味子甲素)的保留时间及其分离情况,从中选择测定五味子乙素的最佳流动相体系。结果表明,在甲醇-水、甲醇-冰醋酸-水的流动相体系中,安五脂素和五味子乙素很难完全分离;而在乙腈-甲醇-水和乙腈-冰醋酸-水流动相体系中,3种木脂素可很好地分离。以乙腈-甲醇-水(体积比为17:58:25)为流动相测定五味子和护肝片中3种木脂素的含量,相对标准偏差(n4)为0.95%～5.8%,平均加标回收率为94.50%～105.6%。将该流动相体系用于供试品中3种木脂素含量的测定,分离效果好,结果令人满意。     

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.     

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.     

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.     

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.     

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.     

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.     

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.