固相萃取-高效液相色谱法测定葡萄酒中白藜芦醇及其糖苷异构体

建立了固相萃取-高效液相色谱(SPE-HPLC)测定葡萄酒中白藜芦醇及其糖苷异构体的方法,并用此方法测定了市售的15种葡萄酒中顺反式白藜芦醇及其糖苷的含量。实验确定了葡萄酒样品中的白藜芦醇及其糖苷的固相萃取方法,通过优化萃取条件,有效地去除了葡萄酒中大量干扰成分。采用Hypersil C18柱(4.6 mm i.d.×250 mm,5μm)分离,以乙腈-水为流动相,线性梯度洗脱,用二极管阵列检测器分别于288 nm和306 nm波长下检测,4种组分分离良好,提高了分析结果的准确性。采用外标法定量,4种组分的质量浓度与其峰面积在一定的范围内有良好的线性关系,相关系数为0.9973～0.9999。4种组分的平均加标回收率为97.4%～98.8%(相对标准偏差为2.1%~3.2%),检测限为0.002~0.005 mg/L。对市售15种葡萄酒的检测结果表明,白藜芦醇作为葡萄酒中重要的生物活性成分,其含量与葡萄酒的酿造方式、葡萄品种、葡萄产地有密切的关系。该方法还可用于其他天然产物中白藜芦醇及其糖苷异构体的测定。     

高效液相色谱法测定红葡萄酒中白藜芦醇的四种异构体

将红葡萄酒用β-葡萄糖苷酶水解处理,使其中的白藜芦醇甙转换成白藜芦醇。采用高效液相色谱法测定水解前后顺、反式白藜芦醇含量的变化,从而计算出葡萄酒中白藜芦醇的4种异构体的含量。色谱柱为Symmetry C18柱(3.9 mm i.d.×150 mm),流动相为乙醇-0.05%乙酸水溶液(体积比为23∶77),紫外检测波长为306 nm。实验结果表明:白藜芦醇的4种异构体在其质量浓度为0.2~50.0 mg/L时均有良好的线性关系(r>0.999),白藜芦醇及其甙的顺、反异构体的最小检出量分别为:0.81     

薄层荧光扫描法测定葡萄酒中的白藜芦醇及其糖苷异构体

建立了薄层荧光扫描法同时测定葡萄酒中顺反白藜芦醇及其糖苷异构体的方法。样品用C18相柱提取,以聚酰胺薄膜为固定相,苯-甲醇-甲酸(10：5：1,V/V)为展开剂进行分离,荧光扫描法定量,4种组分的线性关系良好,相关系数为0．9972-0．9996,平均回收率为97．1％-98．5%,RSD为2．0％-3．2％。对6种市售葡萄酒进行了测定,结果满意。方法简便、快速、灵敏,测定成本低。     

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。     

超高效液相色谱-光电二极管阵列检测-串联四级杆质谱法测定红洋葱中黄酮醇及其糖苷类化合物

采用ACQUITY UPLC HSS T3色谱柱,以含0.1%甲酸的乙腈-水为流动相,0.3 mL/min梯度洗脱方式辅以光电二极管阵列检测-串联四级杆质谱进行定性与定量分析,建立了种同时测定红洋葱中13种黄酮醇及其糖苷类化合物的方法,其中包含6种槲皮素及其糖苷、4种异槲皮素及其糖苷和3种山奈素及其糖苷。结果表明,红洋葱中主要的黄酮醇及黄酮醇糖苷类化合物是槲皮素-4’-葡萄糖糖苷、槲皮素-3,4’-二葡萄糖糖苷、槲皮素和异槲皮素-4’-葡萄糖糖苷。红洋葱的不同部位黄酮醇及其糖苷的含量和分布并不致,以干燥品计算,在相同质量的各部位中,外两层、第三层和内层中总黄酮醇及其糖苷含量的比例为60.3∶33.0∶6.7,其中各部位槲皮素及槲皮素糖苷占黄酮总量的92.1%以上;外两层中黄酮醇单糖糖苷含量大,第三层中黄酮醇苷元含量大,而内层中黄酮醇二糖糖苷含量大。另外,在红洋葱中还发现了少量的山奈素及其糖苷,主要存在于洋葱外层中。本方法简单快速、准确性好,可用于洋葱产品中黄酮醇及其糖苷类化合物的分析。     

葡萄酒中白藜芦醇的固相萃取GC/MS法测定及其生理活性的初步研究

用反向C₁₈固相萃取小柱对葡萄酒进行了预处理,然后用BSTFA硅烷化试剂对萃取物进行了衍生化处理,用气相色谱/质谱对葡萄酒中顺式、反式白藜芦醇进行了同时测定,建立了定量分析方法.对方法的精密度和回收率进行了测定,方法的相对标准偏差分别为4.48%(顺式)和5.23%(反式).顺式、反式白藜芦醇的平均回收率分别为94.4%和97.6%.并对10种国产葡萄酒和两种进口葡萄酒样品进行了测定.对白藜芦醇的生理活性也进行了实验,初步探讨了白藜芦醇对大鼠血管平滑肌细胞(VSMC)、大肠癌细胞株Lovo细胞和小鼠成纤维株3T3细胞的生长生殖活性的影响,观察了其形态变化.     

流动注射化学发光法测定白藜芦醇苷

基于白藜芦醇苷对Luminol KIO4 H2O2体系化学发光的抑制作用,建立了一种快速测定白藜芦醇苷的流动注射化学发光分析法。测定白藜芦醇苷的线性范围为2.0×10-8～8.8×10-6mol L;检出限为6.7×10-9mol L;相对标准偏差为1.9%(c白藜芦醇苷=4.4×10-7mol L,n=11);采样频率为144次 h。该方法可用于葡萄酒和中药虎杖中白藜芦醇苷的测定。     

加压毛细管电色谱对白藜芦醇的分析测定

采用加压毛细管电色谱方法,对白藜芦醇的顺、反异构体的转化以及光照稳定性等进行了研究;同时还对白藜芦醇进行了定性和定量分析研究。在此基础上初步探讨了葡萄酒中白藜芦醇含量的测定研究,从而为我国葡萄酒行业提供了一种通过鉴定白藜芦醇来定量鉴别葡萄酒品质的分析方法。     

高效液相色谱法研究白藜芦醇光致异构化动力学与平衡常数

反式白藜芦醇有多种生理活性,自然资源丰富,但存在光不稳定现象。以光致异构平衡对照品溶液,采用高效液相色谱建立了同时测定顺、反异构体浓度的方法。方法学考察显示符合含量测定要求,反式异构体在1.5~60 μ mol/L、顺式异构体在1.5~55 μ mol/L范围内线性关系良好,R²均达0.999。将该方法应用于研究光致异构化动力学及平衡常数,结果显示反式白藜芦醇在室温避光条件下中性、偏酸性及乙醇介质中稳定;25 ℃时在50%（v/v）乙醇介质中的光异构平衡常数为11.7±0.3。以光致异构平衡液制作标准曲线的策略简单方便,具有可操作性;反式白藜芦醇的稳定性与介质有关,在pH < 7的溶液中光致异构化为一级反应。     

高效液相色谱-串联质谱法检测红葡萄酒中功效成分

建立了高效液相色谱-串联质谱法快速测定葡萄酒中白藜芦醇、黄酮类、多酚类功效成分的分析方法。葡萄酒样品直接稀释后进样,用C18柱进行分离,以乙腈-0.1%(体积分数)甲酸水溶液为流动相进行梯度洗脱,通过多反应监测(MRM)模式进行检测。13种功效成分在各自线性范围内呈良好的线性关系,相关系数均大于0.99。除表没食子儿茶素、没食子儿茶素、儿茶素没食子酸酯、花旗松素的检出限为1.0、1.0、3.0、3.0μg/L外,其他9种化合物的检出限均小于1.0μg/L。回收率为80.9%~112.3%,相对标准偏差小于10%。该方法快速、准确、灵敏度高,适用于葡萄酒中功效成分的快速分析。对实际样品的检测表明,所测葡萄酒样品中均含有儿茶素、表儿茶素、表没食子儿茶素、没食子儿茶素、表儿茶素没食子酸酯/儿茶素没食子酸酯、白藜芦醇、大豆黄素等功效成分,不同品种葡萄酒中这些功效成分含量差异显著。     

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.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

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.