核磁共振代谢组学技术鉴别天然奶油与人造奶油

采用核磁共振(nuclear magnetic resonance,NMR)代谢组学技术对天然奶油和人造奶油的氘代氯仿(CDCl_3)提取物进行了鉴别研究。结果表明:与麦淇淋相比,黄油中甾醇、丁酸、1-戊烯、共轭亚油酸含量较高,而总不饱和脂肪酸、亚油酸的含量较低;与植脂奶油相比,稀奶油中甾醇、丁酸、亚麻酸、亚油酸、1-戊烯、共轭亚油酸、总不饱和脂肪酸含量较高,而总饱和脂肪酸含量较低,并且都具有显著性差异(P0.05)。其中脂肪酸的代谢组学分析结果与气相色谱法所得结果一致。建立的基于NMR代谢组学技术对天然奶油与人造奶油快速、简便的鉴别方法,可以鉴定不同种类奶油的差异化学成分,为奶油制品的品质鉴别和质量控制研究提供分析方法。     

Hydration of Succinic Acid by Ultrasonication and its Effects on Taste

ABSTRACT: We have investigated the possible changes in the hydration of succinic acid aqueous solution by weak ultrasonication based on ¹H-NMR measurements, and observed its effects regarding taste by sensory evaluation. The ¹H-NMR measurements showed that the peak area of the carboxyl proton was diminished in the succinic acid aqueous solution by ultrasonication and that the water proton was conversely enhanced. This means that weak ultrasonication slightly accelerated the hydration of succinic acid. The sensory evaluation showed that the succinic acid aqueous solution tasted weaker by ultrasonication ( p < 0.05), though its concentration was unchanged. These results suggest that the slight change in the hydration state produces some changes in taste.     

Bile Acids Conjugation in Human Bile Is Not Random: New Insights from <Superscript>1</Superscript>H-NMR Spectroscopy at 800 MHz

Bile acids constitute a group of structurally closely related molecules and represent the most abundant constituents of human bile. Investigations of bile acids have garnered increased interest owing to their recently discovered additional biological functions including their role as signaling molecules that govern glucose, fat and energy metabolism. Recent NMR methodological developments have enabled single-step analysis of several highly abundant and common glycine- and taurine- conjugated bile acids, such as glycocholic acid, glycodeoxycholic acid, glycochenodeoxycholic acid, taurocholic acid, taurodeoxycholic acid, and taurochenodeoxycholic acid. Investigation of these conjugated bile acids in human bile employing high field (800 MHz) ¹H-NMR spectroscopy reveals that the ratios between two glycine-conjugated bile acids and their taurine counterparts correlate positively (R ² = 0.83–0.97; p = 0.001 × 10⁻²–0.006 × 10⁻⁷) as do the ratios between a glycine-conjugated bile acid and its taurine counterpart (R ² = 0.92–0.95; p = 0.004 × 10⁻³–0.002 × 10⁻¹⁰). Using such correlations, concentration of individual bile acids in each sample could be predicted in good agreement with the experimentally determined values. These insights into the pattern of bile acid conjugation in human bile between glycine and taurine promise useful clues to the mechanism of bile acids’ biosynthesis, conjugation and enterohepatic circulation, and may improve our understanding of the role of individual conjugated bile acids in health and disease. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Is absolute noninvasive temperature measurement by the Pr[MOE-DO3A] complex feasible

Recently, the feasibility of the praseodymium complex of 10-(2-methoxyethyl)-1,4,7,10-tetraaza-cyclododecane-1,4,7-triacetate (Pr[MOE-DO3A]) for non-invasive temperature measurement via¹H spectroscopy has been demonstrated. Particularly the suitability of the complex for non-invasive temperature measurements including in vivo spectroscopy without spatial resolution as well as first spectroscopic imaging measurements at low temporal resolution (≥4 min) and high temporal resolution (breath hold, ∼20 s) has been shown. As of today, calibration curves according to the particular experimental conditions are necessary. This work aims to clarify whether the Pr[MOE-DO3A] probe in conjunction with¹H-NMR spectroscopy allows non-invasive absolute temperature measurements with high accuracy. The measurement results from two different representative media, distilled water and human plasma, show a slight but significant dependence of the calibration curves on the surrounding medium. Calibration curves in water and plasma were derived for the temperature dependence of the chemical shift difference (F) between Pr[MOE-DO3A]'s OCH₃ and water withF=−(27.53±0.04)+(0.125±0.001)^* T andF=−(27.61±0.02)+(0.129±0.001)^* T. respectivel, withF in ppm andT in °C. However, the differences are minuscule even for the highest spectral resolution of 0.001 ppm/pt, so that they are indistinguishable under practical conditions. The estimated temperature errors are ±0.18°C for water and ±0.14°C for plasma and with that only slightly worse than the measurement accuracy of the fiber-optical temperature probe (±0.1°C). It can be concluded that the results obtained indicate the feasibility of the¹H spectroscopy method in conjunction with the Pr[MOE-DO3A] probe for absolute temperature measurements, with a maximum accuracy of ±0.2°C.     

马来酸氯苯那敏片剂的核磁共振定量测定方法研究

提出测定马来酸氯苯那敏片剂中马来酸氯苯那敏的1↑H-NMR方法。考察了实验条件的影响,选择重水为溶剂,反丁烯二酸为内标,延迟时间为20 s,脉冲宽度为3.0μs,采样次数为16次,内标浓度为4-5mg/mL。在内标与样品质量比为0.48-2.12范围内,峰面积比与质量比之间具有良好的线性关系,相关系数r〉0.999 0,用绝对定量法和标准曲线法测定了3种马来酸氯苯那敏片剂的含量,并与药典的紫外分光光度法作了比较。     

重质油中烃类族组成含量与氢碳原子比、芳香度之间关系的研究

对炼油厂的催化油浆、重催油浆、催化重焦蜡和加氢尾油进行柱分离、元素分析和核磁共振分析 ,研究其氢碳原子比、芳香度与饱和烃加环烷烃、芳烃含量之间的关系。研究结果表明 :前三种油的氢碳原子比、芳香度与重质油的饱和烃加环烷烃、芳烃含量之间存在着良好的线性关系 ,可用线性方程来表示。加氢尾油主要含C2 0～C3 0的正构烷烃 ,芳烃含量小于 1% ,而芳香度大于催化重焦蜡 ,所以用芳香度来评价加氢尾油是不合适的     

漆酶与助剂氧化体系降解苇浆残余木素的研究

用溶剂抽提法制取了苇浆残余木素 ,用漆酶 /助剂和氧气与其反应 ,通过甲氧基的测定、元素分析、1 3C -NMR、1 H -NMR和IR分析研究苇浆残余木素与漆酶 /助剂反应前后结构的变化。研究发现苇浆残余木素在反应后其甲氧基、酚羟基减少 ,醇羟基增多 ,木素结构中羰基增多 ,木素的苯环结构发生了开环反应     

Effect of reactivity of different types of hydroxyl groups of HTPB on mechanical properties of the cured product

The amount of three types of hydroxyl functional groups (G_OH, H_OH, and V_OH) in hydroxyl terminated polybutadiene (HTPB), remaining in samples acetylated to the same extent under two different conditions, viz., fast acetylation using acetyl chloride in presence of N-methyl imidazole catalyst and slow acetylation by acetic anhydride, differed significantly. For the fast acetylation there is a uniform reduction in all the three types of hydroxyls, probably because the reaction becomes random at rapid rates and the reactivity of the different types of hydroxyls does not play a major role. However, in the slow reaction, the reduction of G-type hydroxyls was 30% more than the expected value and there was a corresponding increase in the amount of V-type hydroxyls remaining in the acetylated product, showing reactivity of OH in the order of G > H > V. When the reaction is slow, it becomes selective and the change in reactivity of the three types of OH groups is reflected in the extent of conversion. The mechanical properties and the crosslink density data show a reduction in the samples containing lesser amounts of G_OH, confirming the branching nature of G_OH, which is involved in the crosslinking reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1313–1320, 1997     

酚醛树脂分子结构的1H-NMR分析

以D2O为溶剂,采用^1H-NMR测定不同醛酚摩尔比的碱性酚醛树脂,结果表明,当醛酚比小于2时,D2O中残余氢峰对树脂特征结构分析无干扰．此时可对分子结构进行定量研究．本文还提出了酚醛树脂分子结构的统计模型,结合^1H-NMR测定结果．由该模型推导的方程可以计算出树脂的结构参数．     

Functional peroxides and peroxy oligoesters on the basis of pyromellitic dianhydride

A series of peroxy oligomers has been synthesized on the basis of pyromellitic dianhydride and tetrachloroanhydride of pyromellitic acid by condensation with polyethylene glycols and tert-butylhydroperoxide. The resulting oligoesters contain two types of functional groups: carboxylic – which can participate in ionic reactions and peroxide – able to initiate certain radical processes. Concentrations of these groups depend on the method of synthesis, the nature of starting monomers, and the molecular mass of polyethylene glycol. Structures of oligoesters have been determined by IR and ¹H-NMR spectroscopy. The oligoesters are able to form three-dimensional networks when heated to 400 K. A mechanism of the network formation is proposed. These materials can be used as curing agents for unsaturated polyesters and also for epoxy + unsaturated polyester resin compositions. Electronic Publication