海绵Phyllospongia Foliascens中的双高Scalarane二倍半萜

具有Scalarane碳架的二倍半萜以及C-20单甲基化或C-20和C-24双甲基化的Scalarane型高二倍半萜普遍存在于Dictyoceratida科海绵中,我们从同科海绵Phyllospongia foliascens中已分离及测定了5个结构新颖的双高二倍半萜,本文报道另外2个双高二倍半萜phyllohemiketal A(1)和B(2)的分离和结构测定。     

海绵Ircinia selaginea中一种罕见的长共轭二萜烯酮

海绵的代谢产物中含有多种多样结构新异的生理活性物质[1～ 4 ] ,从中发现了不少抗肿瘤、抗病毒的活性物质 .我们在系统地研究海绵次生代谢产物的生理活性物质中 ,从海绵 Ircinia selagineaL amarck(Dictyoceratida目 ,Thorectidae科 )中分离出一种结构罕见的长共轭二萜烯酮 (1 ) . 1是新化合物 ,命名为 irciniketene,采用波谱方法测定了其化学结构 (Scheme 1 ) .生物活性试验表明 ,化合物 1对肿瘤细胞具有较强的抑制作用 .1 21 31 4 1 5 011 11 92 01 89871 7654 31 6C2 C1 OScheme1　Structure of irciniketene( 1 )1　实验部分1 .1　…     

海绵Phyllospongia sp.中两个新的Scalarane型二倍半萜

海绵Ｐｈｙｌｌｏｓｐｏｎｇｉａｓｐ．中两个新的Ｓｃａｌａｒａｎｅ型二倍半萜万一千，苏镜娱，曾陇梅，王明焱（中山大学化学系，广州，５１０２７５）关键词海绵，二倍半萜，分离，结构鉴定Ｐｈｙｌｌｏｓｐｏｎｇｉａ属含有丰富二倍半萜的海绵体［１～７］，从这种海...     

双高二倍半萜Phyllohemiketal A的光谱研究

从中国南海海绵Ｐｈｙｌｌｏｓｐｏｎｇｉａ ｆｏｌｉａｓｃｅｎｓ中分离得到双高二倍半萜ｐｈｙｌｌｏｈｅｍｉｋｅｔａｌ Ａ（１）本文以质谱和二维核磁共振谱的数据详述Ｐｈｙｌｌｏｈｅｍｉｋｅｔａｌ Ａ的结构测定，并根据偶合常数和ＮＯＥ差谱确定了它的立体化学。     

两个新的海洋倍半萜

从稠密短指软珊瑚Sinularia conferta 中分离得1个新倍半萜confertol(1)。 从荑柔软珊瑚Nephthea albida分离得1个新倍半萜nephalbidol(2)和1个已知的多 羟基甾醇nephalsterol A(3)，应用波谱方法测定了的化学结构和相对构型。     

一个新倍半萜内酯的分离与结构研究

自蒿属植物万年蒿(Artemisia sacrorumLedeb)地上部分分离得三个倍半萜内酯类化合物,经理化常数测定,化学相关及光谱(红外光谱1、H-核磁共振光谱1、3C-核磁共振光谱、质谱)分析,鉴定其结构分别为万年蒿氯内酯chlorosacroratin(Ⅰ),去乙酰氧母菊内酯deacetoxymatricarin(Ⅱ)和ridentin(Ⅲ)。其中,万年蒿氯内酯为一未见报道的新化合物。     

天花粉蛋白一级结构的修正及不同产地天花粉蛋白的研究

胰蛋白酶酶解天花粉蛋白, 用高效液相色谱分离酶解肽段, 用顺序仪测定其有关肽段的顺序。用羧肽酶A, B, Y测定了天花粉蛋白C-端和天花粉蛋白溴化氰降解肽CB1的C-端顺序, 修正了我们1985年测定的天花粉蛋白一级结构, 证明天花粉蛋白由246(7)氨基酸残基所组成, 除C-端微观不均一外, 与Collins结果一致。同时比较了芜湖产天花粉蛋白一级结构与平湖产的天花粉蛋白一级结构, 没有发现两者的一级结构有差别。     

长梗千里光呋喃雅槛兰型倍半萜的结构研究

我们曾从甘肃省漳县采集的长梗千里光全草中分离并鉴定出两个呋喃雅槛兰型倍半萜. 在此基础上, 本文对其脂溶性化学成分进行深入研究, 除了发现倍半萜外, 又分离并鉴定出2个呋喃雅槛兰型倍半萜. 通过IR， UV， MS， CD和NMR等数据分析, 确定了4个化合物的结构, 其中, 化合物3首次在长梗千里光中分离得到, 化合物4是一种新化合物, 通过圆二光谱及核磁共振和NOE差谱研究其立体化学结构, 并按Dreiding models构筑该化合物分子的立体化学结构, 确定该化合物为Non-steroid型构象.     

南中国海星骨海绵Stelletta sp.中的三萜化合物

最近,我们又从采自广西涠洲岛海域的星骨海绵Stelletta sp.中分离得到3个黄色三萜色素1,2和3(见下式).通过IR,UV,MS和1D NMR,2D NMR等方法测定了它们的结构,并对化合物1的所有C和H进行了指认.同时,通过X射线单晶衍射分析测定了化合物1的立体化学结构.初步的药理实验表明,这3个化合物对P388肿瘤细胞均有很强的抑制活性,ED₅₀值依次为0.01,0.5和1.0μg/mL,提示Stelletta属海绵中的这类三萜具有很好的药用开发前景.     

多羟基取代二氢沉香呋喃倍半萜的合成方法

二氢沉香呋喃倍半萜是一类具有杀虫、抑菌等多种活性的天然化合物.由于重要的生物活性和结构的复杂性,从而吸引了有机合成化学家的关注.最近,我们小组从桉烷倍半萜α-(-)-山道年出发,经过NBS促进的四氢呋喃环成环、OsO4双羟基化、环氧化合物的碱重排等一系列官能团转化,合成了七羟基取代的二氢沉香呋喃倍半萜化合物1,进而开拓了一种新颖、简洁的合成多羟基取代二氢沉香呋喃倍半萜的方法,其合成路线如下所示.     

Pattern recognition. An application to the identification of some stereoisomeric N-acetylhexosamines by mass spectrometry

A method is reported for the identification of trimethylsilylated stereoisomeric N-acetyl-hexosamines by application of a pattern recognition procedure to mass spectral data. The selection of characteristic mass spectral data and the pattern recognition procedure are discussed.     

Near-infrared calibration transfer based on spectral regression

A calibration transfer method for near-infrared (NIR) spectra based on spectral regression is proposed. Spectral regression method can reveal low dimensional manifold structure in high dimensional spectroscopic data and is suitable to transfer the NIR spectra of different instruments. A comparative study of the proposed method and piecewise direct standardization (PDS) for standardization on two benchmark NIR data sets is presented. Experimental results show that spectral regression method outperforms PDS and is quite competitive with PDS with background correction. When the standardization subset has sufficient samples, spectral regression method exhibits excellent performance.     

Simplex optimization of the adaptive kalman filter

A method for determining concentrations from overlapped spectral data when a complete model is not available is described. This approach combines simplex optimization with the adaptive Kalman filter to yield a method in which initial guesses for the adaptive filter are generated by the simplex algorithm. The performance of the method is demonstrated by deconvoluting overlapped synthetic data and spectral data.     

Exciton dynamics in molecular crystals from line shape analysis. The use of spectral moments and correlation functions

A method for elucidating exciton dynamics from the profile of ω?_i(ω) is developed and illustrated by using anthracene crystal reflectance data. From the Green's function for the exciton-phonon system, terms contributing to each spectral moment are rendered explicit. The Green's function is related to certain correlation functions which together with the spectral moments are evaluated from the spectral data.     

A Background and noise elimination method for quantitative calibration of near infrared spectra

A new hybrid algorithm is proposed to eliminate the varying background and noise simultaneously for multivariate calibration of near infrared (NIR) spectral signals. The method is based on the use of multi-resolution, which is one of the main advantages provided by wavelet transform. The signals are firstly split into different frequency components, which keep the same data points of the original signals. In conjunction with a modified uninformative variable elimination (mUVE) criterion, the new method can be used to remove the low-frequency varying background and the high-frequency noise simultaneously. The method is successfully applied to simulated spectral data set and experimental NIR spectral data, resulting in more parsimonious multivariate models with higher precision. In addition, the proposed strategy can be applied to other spectral signals as well.     

Improving the linearity of spectroscopic data subjected to fluctuations in external variables by the extended loading space standardization

In process analytical applications, spectral measurements can be subject to changes in process temperature, pressure, flow turbulence, and compactness as well as other external variations. Generally, the variations of external variables influence spectral data in a non-linear manner which leads to the poor predictive ability of bilinear calibration models on raw spectral data. In this contribution, the influence of external variables on spectral data is generally classified into two different modes, multiplicative influential mode and composition-related influential mode. A new chemometric method, termed Extended Loading Space Standardization (ELSS), has been developed to explicitly model these two kinds of influential modes. ELSS was applied to two sets of spectral data with fluctuations in external variables and its performance evaluated and compared with global partial least squares (PLS) models and Loading Space Standardization (LSS). Results show that ELSS can efficiently model the external non-linear effects in both data sets and greatly improve the accuracy of predictions with the mean square error of prediction for test samples being 2-3 times smaller than those of LSS and global PLS.     

Synthesis and spectral studies on Co (II) and Ni (II) complexes with polyfunctional quinazoline-(3H)-4-ones

A series of complexes of Co(II) and Ni(II) with 2-(R)-3-(X)-substituted quinazoline-(3H)-4-ones, where R = methyl/phenyl and X = furalamino, uramino and thiouramino have been synthesised and characterised by analytical, conductivity, thermal and magnetic, infrared and electronic spectral data. Based on analytical and conductivity studies the stoichiometries of the complexes have been established. Conductivity data also show that all these complexes are non-electrolytes. Infrared spectral data indicate that all the ligands manifest neutral bidentate with both the metal ions. Geometries for the complexes have been proposed based on electronic spectral data. Various electronic spectral parameters have been calculated for all the complexes and relevant conclusions have been drawn with respect to the nature of bonds present in them.     

Macrolactin S, a novel macrolactin antibiotic from marine Bacillus sp

A new 24-membered ring lactone, macrolactin S, was isolated from a culture broth of marine Bacillus sp. and its structure was established by various spectral analyses. Macrolactin S is the first macrolactin hydroxylated at C-12. Besides, the known compounds macrolactin A and macrolactin B were also isolated, which were elucidated on the basis of spectral data analyses and literature data comparison. They exhibited antibacterial activity against E. coli and S. aureus.     

Varimax extended rotation applied to multivariate spectroscopic image analysis

A new approach for spectral image analysis called the Varimax extended rotation (VER) has been developed. VER employs a four-step procedure to resolve image data. In the first step, the data are pretreated to ensure they are is in a form suitable for principal component analysis. The second step involves reducing the dimensionality of the data using principal component analysis. In the third step, the significant principal components are rotated to identify single component regions in the spectral image. The fourth step uses alternating least squares (ALS) to improve the estimates of the spectral profiles of each component. Results from simulated and real Raman imaging data of water in oil emulsions demonstrate the efficacy and efficiency of the proposed method.     

中药口服固体制剂原辅料近红外光谱数据库的构建及应用

建立了中药口服固体制剂原辅料近红外(NIR)光谱数据库,采用模式识别方法研究了NIR光谱数据在物料分类和物性预测中的应用。使用便携式近红外光谱仪快速测量149批原辅料粉末的NIR漫反射光谱数据,并录入iTCM数据库。利用主成分分析(PCA)法探究NIR光谱数据对已知结构物料的分类能力,采用偏最小二乘(PLS)法研究了NIR光谱对原辅料物性参数和直接压片片剂性能的预测能力。经标准正态变量变换(SNV)+Savitzky-Golay(SG)平滑+一阶导数处理后的NIR光谱数据对微晶纤维素、乳糖、乙基纤维素、交联聚维酮和羟丙基甲基纤维素这5类辅料的区分能力较好。NIR光谱数据与原辅料粉末粒径、密度和吸湿性的相关性较强。NIR光谱信息作为物料物理性质的补充,可提高粉末直接压片片剂性能预测模型的性能。NIR光谱数据是iTCM数据库物性参数数据的补充,物性参数与NIR光谱数据的结合能更全面地表征原辅料的性质。