合成抗病毒母体三羟基核苷的新方法

三羟基核苷因其具有良好的抗病毒性能及作为核酸代谢作用的抑制剂而受到人们的关注．文献报道的合成方法［１～３］因反应需避光，温度控制要求严格，中间体二醛不稳定［４］，给操作带来困难．产物不易纯化，一般局限于使用离子交换色谱法［５］，而按此方法得到的无环核...     

二溴羟基苯基荧光酮荧光熄灭法测定铜

研究了在pH 6 2～ 8 2磷酸二氢钾 磷酸氢二钠缓冲体系中 ,非离子表面活性剂TritonX 10 0存在下 ,铜 (Ⅱ )与二溴羟基苯基荧光酮 (DBH PF)形成 1∶2红色三元混配合物而使荧光熄灭 ,建立了荧光熄灭法测定铜的新方法。配合物的λex=5 3 0nm ,λem=5 60nm ,含量在 0～ 80 μg·L-1范围内有良好的线性关系 ,检测限为 0 2 μg·L-1。体系的灵敏度高 ,选择性好。Al(Ⅲ )、Fe(Ⅲ )、Ti(Ⅳ )的干扰 ,可用氟化钠、苦杏仁酸掩蔽。方法快速简便 ,用于人发、茶叶及水中微量铜的测定与AAS相符 ,RSD(n=5 ) <6 9% ,回收率在 98%～ 10 4 %之间。     

Spin and fluorescence label studies on bile salt micelles

The interior structure of micelles formed by bile salts, which differ in the number and location of the hydroxyl groups attached to the steroid nucleus, was studied by the spin label and fluorescence label methods. The results show that the interior structure of micelles formed by bile salts possessing two hydroxyl groups is more rigid than that of micelles formed by trihydroxy bile salts regardless of the terminal hydrophilic group. Even in the case of dihydroxy bile salts possessing two hydroxyl groups in the same location, the interior structures of their micelles are different from each other depending on the orientation of their hydroxyl groups. It is considered that hydroxyl groups as well as the terminal hydrophilic group play an important role in the micellar formation of bile salts.     

Structural determination of a new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane from Taxus cuspidata

A new 2(3 --> 20)abeotaxane with an unusual 13beta-substitution pattern and a new 6/8/6-ring taxane were isolated from the methanol extract of the needles of Taxus cuspidata. The structures were established as 2alpha,7beta-diacetoxy-5alpha,10beta,13beta-trihydroxy-2(3 --> 20)abeotaxa-4(20), 11-dien-9-one (1) and 2alpha,5alpha,7beta,9alpha,13alpha-pentahydroxy-10beta-acetoxytaxa-4(20),11-diene (2) on the basis of 1D and 2D NMR spectral data and high-resolution FAB-MS analyses.     

新试剂3,5-二溴-4-偶氮间苯二酚苯基荧光酮与锗配合物的分光光度法研究

本文研究了在表面活性剂Ｔｗｅｅｎ６０存在下，新试剂３，５－二溴－４－偶氮间苯二酚苯基荧光酮与锗（Ⅳ）的显色反应和光度性质。在０．５～１．５ｍｏｌ／ＬＨＣｌ介质中，锗与试剂形成１２的红色三元胶束配合物，最大吸收波长为５３２ｎｍ，表观摩尔吸光系数ε为１．６８×１０５Ｌｍｏｌ－１ｃｍ－１，锗浓度在０～５μｇ／２５ｍｌ范围内符合比尔定律。拟定方法用于煤样中微量锗的分析，结果满意。     

反式-5,1O,15-三芳基-5,1O,15-三羟基-1-氢-三苯并[a,f,k]三茚的合成与从头算结构分析

合成了两个具有三个羟基的新型主体分子反式－5,10,15－三芳烃－5,10,15－三羟基－1－氢－三苯并[a,f,k]三茚（芳基分别为苯基和－萘基）,并通过从头算对其及其异构体的结构进行了分析,结果发现当芳基为苯基时,其顺式异构体分子印环中所有原子不完全处于共平面,而其反式异构体和1－萘基的顺反异构体均处于共平面。     

A New Megastigmane Palmitate and a New Oleanane Triterpenoid from Aster yomena Makino

A new megastigmane palmitate, 9‐oxomegastigm‐5(13)‐ene‐2β‐palmitate ( 1 ), and a new oleanane triterpenoid, (3β)‐3,23,28‐trihydroxyolean‐12‐en‐11‐one ( 2 ), together with three known oleanane‐type triterpenoids, β‐amyrin ( 3 ), erythrodiol ( 4 ), and (3β)‐olean‐12‐ene‐3,23,28‐triol ( 5 ), were isolated from the aerial parts of Aster yomena (Asteraceae). Their structures were identified based on 1D‐ and 2D‐NMR analysis, including ¹H,¹H‐COSY, HSQC, HMBC, and NOESY techniques.     

Stereoselective Total Synthesis of the Natural Oxylipin (6R,7E,9R,10S)‐6,9,10‐Trihydroxyoctadec‐7‐enoic Acid

The stereoselective total synthesis of the natural oxylipin, (6R,7E,9R,10S)‐6,9,10‐trihydroxyoctadec‐7‐enoic acid, has been accomplished using nonanal and hexane‐1,6‐diol as the starting materials. The synthesis involves Sharpless kinetic resolution, asymmetric epoxidation, and olefin cross‐metathesis as the key steps.     

溴化十六烷基三甲胺存在下5''''-硝基水杨基荧光酮与铋的显色反应及其应用

在阳离子表面活性剂溴化十六烷基三甲胺（ＣＴＭＡＢ）存在下，于ｐＨ８．０～９．０的Ｈ３ＢＯ３－ＮａＯＨ缓冲介质中，铋（Ⅲ）与新显色剂５′－硝基水杨基荧光酮（５′－ＮＳＦ）反应生成组成比为１∶３的水溶性和稳定性皆佳的红色配合物，其吸收峰波长为５４４ｎｍ，表观摩尔吸光系数为１．４６×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，线性范围为０～７．０μｇ／１０ｍＬ。采用巯基棉分离，能够消除许多金属离子的干扰。用于焊锡和铸造锡合金中微量铋的测定，相对误差为３．０％，相对标准偏差不大于０．９０％（ｎ＝６），回收率为９５．７～９９．３％。     

Determination of the flavone tricin in human plasma by high-performance liquid chromatography

Tricin is a flavone constituent of brown rice and rice bran, which interferes potently with the survival of human-derived breast and colon cancer cells in vitro. A specific and simple high-performance liquid chromatographic (HPLC) method was developed for the determination of tricin in human plasma with UV-visible detection. HPLC separation on Hypersil-BDS C(18) (4.6 x 250 mm) was carried out with an isocratic mobile phase of 52% methanol in 0.1 m ammonium acetate, pH 5.10, containing 0.27 mm disodium ethylenediamine tetraacetic acid and detection at 355 nm. The retention times of tricin and quercetin (internal standard) were 14.2 and 7.8 min, respectively. The assay was linear in the range 1-100 microg/mL (r(2 ) > or = 0.995). Tricin in plasma was efficiently extracted with 0.1 m acetic acid in acetone, and the recoveries were in the range 92.6-102.8% (n = 6) with relative standard deviation below 10% for three concentrations of tricin, 5, 10 and 100 microg/mL. The lower limit of quantitation (relative standard deviation <20%) was 1 microg/mL.