抗哮喘药中间体7一氯喹哪啶合成技术进展

7-氯喹哪啶是一种重要的药物中间体,其合成方法受到广泛关注.叙述了7-氯喹哪啶的合成方法及应用的最新进展,主要介绍了氧化剂、合成方式及原料选择对7-氯喹哪啶制备收率的影响,同时也介绍了7-氯喹哪啶和5 -氯喹哪啶的分离方法.     

烯肟菌酯高效体的合成与杀虫活性

研究了烯肟菌酯2个高杀菌活性异构体的合成,通过工艺条件控制,可减少无效体的生成。对分离出的4个异构体分别进行了黏虫、桃蚜的杀虫活性测定。结果表明,其中的2个异构体表现出较好的杀虫活性。     

Density isomer of nuclear matter in an equivalent mass approach

The equation of state of symmetric nuclear matter is studied with an equivalent mass model. The equivalent mass of a nucleon has been expanded to order 4 in density. We first determine the first-order expansion coefficient in the quantum hadron dynamics, then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density. It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value. The model dependence of the conclusion has also been checked by varying the first-order coefficient.     

Short communication: The effect of increasing concentrations of different methionine forms and 2-hydroxy-4-(methylthio)butanoic acid on genes controlling methionine metabolism in primary bovine neonatal hepatocytes

The d-isomer of Met cannot be used directly by the mammary gland in dairy cows; instead, it is transformed into l-Met, the proteogenic isomer, in the liver and other extramammary tissues. It remains unclear whether different Met forms and a Met hydroxy analog, 2-hydroxy-4-(methylthio)butanoic acid (HMB), are metabolized and function similarly in the liver. The objective of the present study was to examine the regulation of key genes in Met regeneration, transulfuration, and transmethylation pathways in response to increasing doses of different Met forms. Hepatocytes isolated from 4 calves between 4 and 7 d old were maintained as monolayer cultures for 24 h before addition of treatments. Treatments of (0, 10, 20, 40 µM) d-Met, l-Met, dl-Met, dl-HMB, or a 1:1 mixture of dl-Met and dl-HMB were added to Met-free medium in triplicate. After 24 h, cell lysates were collected for quantification of gene expression by quantitative PCR, and mRNA abundance was normalized to the mean of 3 reference genes. Data were analyzed with PROC MIXED of SAS 9.3 (SAS Institute Inc., Cary, NC). Analyses of covariance confirmed equivalent slopes of Met form, and the final model included form, dose, and random effect of calf within form. Data are reported as least squares means ± standard error. No main effect of Met form was observed for any genes examined. The enzymes encoded by betaine-homocysteine methyltransferase (BHMT) and 5-methyltetrahydrofolate-homocysteine methyltransferase use betaine and 5-methyltetrahydrofolate, respectively, to regenerate Met from homocysteine. Increasing concentration of Met did not alter 5-methyltetrahydrofolate expression, but decreased BHMT expression. Expression of glycine N-methyltransferase, the enzyme that controls transmethylation flux from S-adenosyl-methionine, was not affected by Met concentration. Methionine concentration had no effect on expression of cystathionine β-synthase, a key enzyme for the transulfuration pathway. The decrease in BHMT expression indicates a decreased need for cellular Met regeneration with increasing Met concentration, independent of Met form. The lack of differences among Met forms on regulating genes examined indicates that all Met forms similarly reduced genes controlling Met regeneration and metabolism in primary bovine hepatocytes.     

二步法制备稀有人参皂苷Rh1组异构体

本论文以制备人参皂苷Rh1为目标,选择三醇类人参皂苷Re为底物,采用酶转化和金属离子催化联用的二步法催化转化,研究了各步骤中的催化反应条件,并对产物进行了纯化和组成分析。结果表明:Absidia sp. P39r菌株产酶能催化转化Re生成Rg1,确定其最佳反应条件为:缓冲液pH5.0,反应温度40 ℃,底物浓度1.2%,反应时间16 h,乙醇浓度10%,在此反应条件下得到的Rg1质量分数最高,为70.5%。然后以Rg1为底物,确定在乙醇-水体系下Fe3+的催化反应产物20(S,R)-Rh1的质量分数最高,催化反应条件优化结果为:乙醇浓度50%,反应温度50 ℃,底物浓度1.7%,Fe3+溶液反应浓度1.4 mol/L,反应时间14 h,20(S,R)-Rh1的质量分数高达61.83%,Rk3、Rh4的质量分数之和为27.34%。在上述条件下将20 g人参皂苷Re与酶液反应,反应结束后用AB-8大孔吸附树脂分离干燥得到含有Rg1的产物14.1 g。再取10.2 g反应得到的Rg1与Fe3+溶液反应,干燥后最终得到的人参皂苷Rh1组异构体质量为8.18 g,得率为80.2%,其中20(S)-Rh1,20(R)-Rh1,Rk3和Rh4的含量分别为37.71%,24.12%,7.27%,20.07%。     

二酚异构体的制取和用途

本文说明二甲酚异构体的生产、性质和应用，有助于对其开展综合利用。     

类胡萝卜素立体异构体构效关系及其应用研究进展

类胡萝卜素是水果、蔬菜等膳食原料中广泛存在的天然色素,由于分子中存在大量的共轭双键,类胡萝卜素能形成较多的立体异构体。果蔬中天然存在的类胡萝卜素主要为全反式构型,但人体中检测到的类胡萝卜素顺式异构体占比较高。因此,全反式类胡萝卜素的构型转化,类胡萝卜素的空间构型与生理活性的关系引起了研究人员的关注。作者通过文献查阅、产品调研、国内外法规比较,综述了类胡萝卜素顺式异构体的制备方法、不同异构体的检测分析方法、稳定性评价、生理活性及应用的研究进展,为进一步研究类胡萝卜素的空间构型及其应用提供参考。     

C30-HPLC-PDA分离与鉴定β,β-胡萝卜素几何异构体

在装备了二极管阵列(PDA)检测器的HPLC上,应用C30固定相,β,β-胡萝卜素的几何异构体获得了良好的分离。分离条件为:固定相=YMCCarotenoidS-5(4.6×250mm)柱;流动相A=乙腈:甲醇:三乙胺(75:25:0.05,V/V);流动相B=甲基叔丁基醚(MTBE)-三乙胺(100:0.05,V/V);线性梯度:B在20min内由0%增至80%;流速=1.0ml/min;PDA波长范围=260～700nm;进样量=20μl。根据各组分的色谱行为、光谱特征和在碘催化下发生几何异构的产物分析,13,13’-、11,11’-、9,9’-顺式和全反式异构体被鉴定。本项研究的结果奠定了应用C30-HPLC-PDA定量检测β,β-胡萝卜素的几何异构体的基础。     

应用C30-HPLC-PDA-ELSD估算番茄红素顺式异构体吸光系数

由于参比样品的匮乏,番茄红素顺式异构体的吸收光谱定量需基于其吸光系数.采用C30-HPLC-PDA-ELSD系统,参照已公布的全反式异构体的吸光系数(A1%1cm=3 400),根据其光谱峰面积与质量峰面积之比,估算出9,9'-顺式异构体、11,11'-顺式异构体和13,13'-顺式异构体的吸光系数分别为2 100、1 819和1 134.这一结果揭示了番茄红素分子中的顺式异构位置、最大吸收波长(λmax)处的吸光系数与顺式峰相对峰高之间的关系,奠定了在C30-HPLC上定量顺式异构体的基础,具有显著的应用价值.在方法上,尝试使用在线串联光谱和质量检测器测定目标化合物的吸光系数.     

Identification of Geometrical Isomers and Comparison of Different Isomeric Samples of Astaxanthin

Abstract: A high‐performance liquid chromatographic (HPLC) analysis system for isomeric astaxanthin was developed. The separation system consisted of a C₃₀ column and an elution system of methanol/MTBE/water/dichloromethane (77 : 13 : 8 : 2, v/v/v/v). Using the combination of HPLC diode array detector and HPLC atmospheric pressure chemical ionization mass spectrometry, 11 geometrical isomers and 4 epoxides of astaxanthin were successfully identified. Referred to crystal, only isomerization with different degrees was found for solvent dissolving and iodine catalysis, while melting of astaxanthin caused isomerization, slight oxidation, and more noticeable polymerization confirmed by gel permeation chromatography. Chemical changes in isomeric samples all caused a decrease in UV content. The vibrational spectra (infrared and Raman) showed that epoxide was the only new functional group generated for melting. Changes of several key bands and formations of new bands were found in iodine catalysis and melting samples because of isomerization. Practical Application: Eleven geometrical isomers and 4 epoxides, which were normally generated for solvent dissolving, iodine catalysis, and melting of astaxanthin, have been identified by C₃₀‐HPLC‐MS technology. Furthermore, different samples were measured by gel permeation chromatography, UV, infrared, and Raman, based on the analysis of messages, the effect of each processing was well understood.