丝光沸石催化剂上正己烷异构化反应机理

以轻质烷烃异构化中试放大用的丝光沸石催化剂为研究对象,运用“原位”红外反应技术和催化剂活性评价手段,并结合反应动力学参数计算,探讨了正已烷异构化反应机理。结果表明,可用五配位反应中间物种机理解释正碳离子的生成。用双分子六元环反应中间物机理能较好地解释正已烷在氢型丝光沸石(HM)上的异构化过程。对正已烷在Pd/HM上的反应过程也可用正碳离子机理结合双分子六元环中间物机理解释。     

3,4-Bis(3′-hydroxyphenyl)hexane — A new mammary tumor-inhibiting compound

Summary The syntheses of the hexestrol derivatives 3,4-bis-(3-hydroxyphenyl)hexane (4a), 3,4-bis(4-fluoro-3-hydroxyphenyl)hexane (4b), 3,4-bis(3, 4dihydroxyphenyl)hexane (4c), and 3,4-bis(3,4-diacetoxyphenyl)hexane (4d) are described. All compounds showed a marked, competitive inhibition of the estradiol receptor interaction (K _a4c>K_a4a>K_a4d>K_a4b). Evaluated in the mouse uterine weight test compounds 4c and 4d almost reached the estrone effect, whereas 4a and 4b did not produce full uterotrophic response. Compounds 4a-d antagonized the estrone stimulated uterine growth of the immature mouse. Compound 4a (NSC-297170) exhibited a specific, dose-related growth inhibition of the estrogen responsive MCF-7 human breast tumor cell line. Tested on the 9,10-dimethyl-1,2-benzanthracene-induced hormonedependent mammary adenocarcinoma of the Sprague-Dawley rat all compounds showed marked inhibition of tumor growth. As in all experiments compounds 4a and 4b, which is resistant to hydroxylation in 4position exhibited an identical pattern of action, which is different from that shown by compound 4c, the effect of compound 4a cannot be explained by its possible catechol metabolite 4c.Supported by grants from the Deutsche Forschungsgemeinschaft and the Verband der Chemischen Industrie-Fonds der Chemischen Industrie     

The mechanism of vasorelaxation induced by Schisandra chinensis extract in rat thoracic aorta

Aim of the study

Schisandra chinensis (SC) is a known medical herb for the treatment of cardiovascular symptoms associated with menopausal symptoms in Korea. However, the pharmacological action mechanisms involved have not been well studied. This study was aimed to investigate the vascular effects of SC in rat thoracic aorta.

Materials and methods

We isolated the hexane, chloroform, and methanol extracts from SC and evaluated their vasodilatory effects in the rat thoracic aorta.

Results

Hexane extracts of SC (SCHE, 5 × 10⁻⁵ to 10⁻³ g/L) caused a concentration-dependent relaxation in both endothelium-intact and -denuded aortas. The relaxant effect of SCHE on the endothelium-intact aorta was more prominent than on the endothelium-denuded aorta. The former was significantly attenuated by L-NAME, a nitric oxide synthase inhibitor, and ODQ, a soluble guanyl cyclase inhibitor, but not by tetraethylammonium, a nonselective blocker of K⁺ channels, and indomethacin, a cyclooxygenase inhibitor. Furthermore, SCHE caused nitrite production as well as eNOS activation in aortic segments, suggesting implication of NO signal pathway in SCHE-induced relaxation. In endothelium-denuded aorta, SCHE-induced vasorelaxation was also attenuated by calyculin A, an inhibitor of myosin light chain (MLC) phosphatase, but not by ML-9, a MLC kinase inhibitor, suggestive of implication of MLC phosphatase activation. Phenylephrine-enhanced MLC phosphorylation ratio was significantly attenuated by SCHE, which was recovered to the control level by pretreatment with calyculin A.

Conclusions

Taken collectively, these findings suggest that the vascular relaxation evoked by SCHE was mediated by not only endothelium dependent NO pathway but also direct effect on vascular smooth muscle cell via dephosphorylation of MLC.     

Animal models to test drugs with potential antidiabetic activity

Although medicinal plants have been historically used for diabetes treatment throughout the world, few of them have been validated by scientific criteria. Recently, a large diversity of animal models has been developed to better understand the pathogenesis of diabetes mellitus and new drugs have been introduced in the market to treat this disease. The aim of this work was to review the available animal models of diabetes and some in vitro models which have been used as tools to investigate the mechanism of action of drugs with potential antidiabetic properties. In addition, a MEDLINE/PUBMED search for articles on natural products, pancreatectomy and diabetes mellitus treatment published between 1996 and 2006 was done. In the majority of the studies, natural products mainly derived from plants have been tested in diabetes models induced by chemical agents. This review contributes to the researcher in the ethnopharmacology field to designs new strategies for the development of novel drugs to treat this serious condition that constitutes a global public health.     

原料药泛昔洛韦中残留溶剂测定方法研究

目的:建立原料药泛昔洛韦中残留溶剂甲醇,乙酸乙酯,二氯甲烷和正己烷限度检查的含量测定方法。方法:顶空气相色谱法,氢火焰离子化检测器,以水为溶剂,丁酮为内标,色谱柱为石英毛细管色谱柱:HP-1(30m×0.32mm,膜厚1.05μm)。结果:4种残留溶剂在对应于限度的50%～150%浓度范围内有良好的线性关系(r=0.9974～0.9999),平均回收率为82.0%～113.0%。结论:方法简单、可靠、精确,可用于原料药残留溶剂含量控制。     

毛细管气相色谱法测定拉米夫定中有机溶剂的残留量

目的:建立以毛细管气相色谱法测定拉米夫定中有机溶剂残留量的方法。方法:色谱柱为DB-624石英毛细管柱,柱温采用程序升温,载气为氮气,流速为40mL.min-1,进样口温度为230℃,检测器温度为250℃,分流比为20∶1。结果:有机溶剂甲醇、乙醇、乙酸乙酯、正己烷和吡啶的检测浓度的线性范围分别为60.0～420.0(r=0.9993)、100.0～700.0(r=0.9998)、100.0～700.0(r=0.9997)、5.8～40.6(r=0.9991)、4.0～28.0μg.mL-1(r=0.9999);平均回收率为98.4%～100.1%(RSD=2.0%～3.2%);最低检出限为0.26～0.88ng;3批样品中5种有机溶剂残留量均符合《中国药典》要求。结论:本方法简单、准确、灵敏度高、重现性好,可用于该制剂中有机溶剂残留量的测定。     

Partial conduction blocks in N-hexane neuropathy

Nerve conduction blocks, defined by a significant reduction in amplitude or area of the compound muscle action potential at proximal compared with distal sites of stimulation, have been described in glue-sniffers and in workers with industrial exposure at an early stage of n-hexane neuropathy. The frequency with which this focal conduction anomaly appears is described and discussed in the case of a very homogeneous group of 10 young workers diagnosed with n-hexane polyneuropathy. Partial conduction blocks occurred in only two workers and may have been related to the intensity and duration of toxic exposure.     

印刷作业对工人神经行为功能的影响

目的　通过对印刷作业场所的职业卫生调查 ,探讨印刷作业对工人神经行为功能的影响。方法　采用世界卫生组织推荐的神经行为核心测试组合 (NCTB) ,分别对某印刷厂 76名同时暴露于正己烷、混苯 (苯、甲苯、二甲苯 )的工人 (暴露组A)与 5 9名暴露于混苯的工人 (暴露组B)以及 5 1名不接触任何职业有害因素的工人 (对照组 )进行神经行为功能测试。结果　两暴露组在紧张 焦虑、困惑 迷茫、手提转捷度、目标追踪的错误打点数、数字跨度方面与对照组相比差异有显著性 (P <0 0 5 ) ,两暴露组之间各项指标差异无显著性 (P >0 0 5 )。结论　印刷作业环境中正己烷及混苯对工人的神经行为功能可产生一定的影响     

Efficient and practical syntheses of a stable labelled form of the non‐narcotic analgesic,bicifadine and its metabolites

An efficient and practical synthesis of deuterium‐labelled bicifadine, together with 3 deuterium‐labelled bicifadine metabolites, was developed. The levels of deuterium incorporation are high, and the products were used as internal standards in bioanalytical method development and clinical bioanalysis. Copyright © 2007 John Wiley & Sons, Ltd.     

载钯量对轻质烷烃异构化催化剂(Pd/HM)性能的影响

采用MR-GC80型压力微反装置,在空速2h~(-1)、氢油分子比8:1、氢压2MPa、反应温度260℃和280℃反应条件下,考察了钯/氢型丝光沸石(Pd/HM)催化剂的含钯量对正己烷异构化反应活性,选择性,稳定性的影响,并结合脉冲激反装置对反应机理进行了探讨。结果表明:钯含量在0.025—0.25%范围内,活性和选择性均随含钯量的增加而提高;超过0.85%,则呈下降趋势;HM载钯后稳定性有明显的改善。催速失活试验表明:0.25%Pd/HM和0.5% Pd/HM催化剂具有相同的稳定性。在Pd/HM上正己烷异构化反应的机理为酸性和双功能结合的复合机理。