略大凹顶藻中的新碘代内酯化合物

凹顶藻属于红藻，国际上有关凹顶藻化学成分的研究十分活跃[1~3]，凹顶藻的代谢物大多是萜类化合物，尤其是倍半萜．我们首次研究了采自南中国海西沙群岛海域的略大凹顶藻．生物活性测定结果表明该藻体的乙酸乙酯抽提物具有植物激素作用，且对油菜菌核有中等杀菌作用．从总抽提物中首次分离到一种新的碘代内酯（1，结构见下式）以及胆甾醇和正-二十酸．氯代或溴代化合物在海洋生物的次生代谢物中较常见，但是碘代化合物是较少有的．1结果与讨论碘代内酯（1）为带有特殊香气的白色固体．EIMS高质量区出现m／z550[M+]及423[M-I]+的峰，表明…     

国产甘薯叶黄酮类成分研究

用高效液相色谱法分离和制备了国产甘薯叶中黄酮类化合物，经波谱分析，分别鉴定为：槲皮素－３－ｏ－β－Ｄ－葡萄糖－（６→１）－ｏ－α－Ｌ－鼠李糖甙（１），４＇，７－二甲氧基山柰酚（２），槲皮素－３－ｏ－β－Ｄ－葡萄糖甙（３）和槲皮素（４）。     

刺五加叶中黄酮类化合物的结构鉴定

利用电喷雾质谱发现刺五加叶中存在4种黄酮类化合物，进一步分离得到其中的两种，经核磁质谱鉴定，一种为槲皮甙（槲皮素－3－O－α-L鼠李糖），另一种为金丝桃甙（槲皮素－3－O－β-D-半乳糖），其余两种难以分离的黄酮甙经电喷雾多级串联质谱分析，初步推断为槲皮素和芦丁（槲皮素－3－O－芦丁糖），以上4种均为黄酮醇类化合物，除金丝桃甙外，其它3种为刺五加叶中尚未见报道的黄酮类成分。     

1－O－酰基－2，3，4－三－O－乙酰基－β－D－吡喃木糖及吡喃阿拉伯糖的合成

１－Ｏ－酰基－２，３，４－三－Ｏ－乙酰基－β－Ｄ－吡喃木糖及吡喃阿拉伯糖的合成薛良驹，孙关中，高建军（新疆大学化学系，乌鲁木齐８３００４６）本文用乙酰基保护的ａ－９－溴代吡喃木糖和ａ－Ｄ－溴代吡喃阿拉伯糖与羧酸类化合物在三乙基苄基溴化铵（ＴＥＢＡＣ）...     

碘酸钾存在下极谱催化波法测定陈皮甙

基于陈皮甙在ＫＩＯ３存在下产生的极谱催化波，拟定了测定陈皮甙的新方法。在 ０．５５ ｍｏｌ／Ｌ ＨＡｃ－０．０１ｍｏｌ／Ｌ　ＮａＡｃ（ｐＨ ４．００±０．０５）－１．０×１０～（－３）ｍｏｌ／Ｌ ＫＩＯ３缓冲溶液中，陈皮甙催化波的峰电位为－１．３５ Ｖ（ｖｓ，ＳＣＥ），它的一阶导数峰峰电流与陈皮甙浓度在２．６ × １０～（－７）～２．６ × １０～（－６）ｍｏｌ／Ｌ范围内呈线性关系（ｒ＝０．９９７０，ｎ＝６）。本方法比现有的电化学方法灵敏度高一个数量级。可用于直接测定中草药贯众水提液中陈皮甙含量。     

朝藿甙E的分离和结构

从朝鲜淫羊藿的地上部分分离到２个化合物，经化学和光谱方法鉴定它们为５，７－二羟基－４＇－甲氧基－８－异戊烯基黄酮－３－Ｏ－β－Ｄ－（２－Ｏ－乙酰基）－葡萄吡喃糖基－（１－３）－α－Ｌ－（４－Ｏ－乙酰基）－鼠李吡喃糖基－７－Ｏ－β－Ｄ－葡萄吡喃糖甙（Ｉ）和β－乐淫羊藿素（Ⅱ），其中Ｉ是未见报道的化合物命名为朝藿甙－Ｅ，Ⅱ为首次从该植物中获得。     

2，3，4－三苯甲酰化－1－β－氰基－D－吡喃木糖构象研究

２，３，４－三苯甲酰化－１－β－氰基－Ｄ－吡喃木糖构象研究张亮仁，张礼和（北京医科大学天然药物及仿生药物国家重点实验室，北京，１０００８３）关键词吡喃木糖，分子模拟，构象，分子动力学计算碳核苷类化合物是人们广泛关注的一类抗肿瘤抗病毒化合物［１～４］。...     

胀果皂甙Ⅲ和Ⅴ的结构鉴定

从胀果甘草根茎中获得２个皂甙（１和３），依其理化性质和波谱分析，将其结构确定为：异甘草次酸－３－Ｏ－β－Ｄ－６＂－正丁基－吡喃葡萄糖醛酸基－（１→２）－β－Ｄ－６＇－乙基－吡喃葡萄糖醛酸甙（１）、异甘草次酸－３－Ｏ－β－Ｄ－６＂－正丁基－吡喃葡萄糖醛酸基－（１→２）－β－Ｄ－６＇－正丁基－吡喃葡萄糖酸甙（３），分别命名为胀果皂甙Ⅲ、胀果皂甙Ⅴ。     

朝藿甙－C的分离和结构

从朝鲜淫羊蕾的地上部分分离得到４个化合物。经化学和光谱方法鉴定它们为：５，７，３＇－三羟基－４＇－甲氧基－８－异戊烯基黄酮醇－３－Ｏ－α－Ｌ－鼠李吡喃糖甙（Ⅰ）、ＩｃａｒｉｓｉｄｅＣ１（Ⅱ）、Ｅｐｉｍｅｄｏｋｏｒｅａｎｏｓｉｄｅ－Ⅰ（Ⅲ）和Ｄｅｓｍｅｔｈｙｌｉｃａｒｉｔｉｎ（Ⅳ）。其中Ⅰ是未见报道的新化合物，命名为朝藿甙－Ｃ；Ⅱ、Ⅲ和Ⅳ首次从该植物中获得。     

碳核苷的合成及生物活性研究

通过呋喃汞盐与溴代木糖的偶合，合成５个新碳核甙；经过元素分析，＾１ＨＮＭＲ，＾１３ＣＮＭＲ，ＭＳ，ＩＲ确定了它们的结构；并检验了其中两个化合物对α－及β－硫代葡糖苷酶的抑制活性。     

HEPT类化合物的QSAR研究

为定量结构／活性相关性研究提取了量子化学参数,拓扑指数Am,分子连接性指数^mxt及疏水性常数,同时应用正交变换和最佳变量子集算法（Leaps-and-Bonds)进行了变量压缩和选择,进而实施了多元回归分析,并由此结果进行了HEPT类化合物（1－[(2-hydroxyethoxy)methyl]-6-(phenylthio)-thymine derivatives)的结构／活性关系的理论解释,进行了人工神经网络法对于该类化合物的活性预测,其结构明显好于多元回归法。     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shifts of the ring protons on the pH of the medium for a number of 4-hydroxyquinoline derivatives was studied by means of PMR spectroscopy. The dipolar and uncharged hydroxy forms exist in equilibrium in aqueous solutions. The effect of intramolecular hydrogen bonding on the character of the dependence of the chemical shift on the pH of the medium in the case of 3-piperidinomethyl-4-hydroxyisoquinoline was investigated. The possibility of the separate protonation of the ring nitrogen and the side-chain nitrogen in 3-piperidinomethyl-4-hydroxyisoquinoline was established. The distribution of the -electron density in 4-hydroxyisoquinoline is in good agreement with its chemical behavior.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1546–1549, November, 1971     

Effect of the pH of the medium on the chemical shifts in the PMR spectra and on the distribution of the π-electron density

The dependence of the chemical shift of the ring protons on the pH of the medium for a number of 3-hydroxyquinoline derivatives was studied by PMR spectroscopy. The regions of ionization of the molecules, which correspond to the ranges of acidic, neutral, and alkaline media, were found. In D₂O, 3-hydroxyquinoline is present only in the uncharged hydroxy form. The presence of intramolecular hydrogen bonding in 4-dimethylaminomethyl-3-hydroxyquinoline has a substantial effect on the character of the dependence of the chemical shift on the pH of the medium; the existence of separate protonation of the nitrogen atoms of the ring and the side chain of 4-dimethylaminomethyl-3-hydroxyquinoline was established. The distribution of the -electron density in the 3-hydroxyquinoline molecule is in good agreement with its chemical behavior during electrophilic substitution.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1540–1545, November, 1971.     

On the theory underlying the Car-Parrinello method and the role of the fictitious mass parameter

The theory underlying the Car-Parrinello extended-Lagrangian approach to ab initio molecular dynamics (CPMD) is reviewed and reexamined using "heavy" ice as a test system. It is emphasized that the adiabatic decoupling in CPMD is not a decoupling of electronic orbitals from the ions but only a decoupling of a subset of the orbital vibrational modes from the rest of the necessarily coupled system of orbitals and ions. Recent work [J. Chem. Phys. 116, 14 (2002)] has pointed out that, due to the orbital-ion coupling that remains once adiabatic decoupling has been achieved, a large value of the fictitious mass mu can lead to systematic errors in the computed forces in CPMD. These errors are further investigated in the present work with a focus on those parts of these errors that are not corrected simply by rescaling the masses of the ions. It is suggested that any comparison of the efficiencies of Born-Oppenheimer molecular dynamics (BOMD) and CPMD should be performed at a similar level of accuracy. If accuracy is judged according to the average magnitude of the systematic errors in the computed forces, the efficiency of BOMD compares more favorably to that of CPMD than previous comparisons have suggested.     

液滴荧光传感与计算机联用技术在微量分析中的应用

通过在LS55型荧光-磷光-发光分光光度计上加装液滴产生及调节附件,采用计算机采集与分析处理数据,成功地研制了双通道液滴光化学传感装置.利用葡聚糖凝胶对复合维生素B中不同组分的选择性吸附来达到分离与同时检测的目的,并将其用于复合维生素B药片的分析,取得了满意的结果.