Simultaneous quantitation of ceramides and 1,2-diacylglycerol in tissues by latroscan thin-layer chromatography-flame-ionization detection

Ceramides and 1,2-diacylglycerol have been demonstrated in intracellular signaling pathways. A method of simultaneous mass determination of ceramides and 1,2-diacylglycerol in tissues was developed using the latroscan which combines thin layer chromatography and flame ionization detection (TLC/FID) techniques. Because of relatively low amounts of these components in tissues, the fraction of nonpolar lipids, which included ceramides and glycerides, was eluted with chloroform/acetone mixture (3∶1, vol/vol) through a silicic acid column to eliminate the polar phospholipids. Development of Chromarods was carried out using three solvent systems in a four-step development technique. The relationship of the peak area ratio to weight ratio compared with cholesteryl acetate added as an internal standard was linear. The amount of ceramides increased with incubation of rat heart homogenate and human erythrocyte membranes in the presence of sphingomyelinase (E.C. 3.1.4.12). The latroscan TLC/FID system provided a quick and reliable assessment of ceramides and 1,2-diacylglycerol.     

Analysis of lipid classes and lipofuscin substances by high performance liquid chromatography

The fractionation and analysis of the lipid classes and fluorescent substances of animal tissues by high performance liquid chromatography (HPLC) using a combination of fluorescence and flame ionization detectors is described. The lipid classes and fluorescent substances are extracted from rat kidney and liver tissue by a new method that involves preextraction of nonlipid and aqueous-soluble fluorescent substances with hot dilute (0.05 N) acetic acid. The lipid classes and organic-soluble fluroscent substances are extracted from the residual tissue in three extractions: the first with chloroform/methanol, 1:1, v/v; the second with chloroform/methanol, 1:2, v/v; and the third with methanol. The fractionation of these compounds by HPLC is carried out with a column 0.2×45 cm, packed with a special adsorbent prepared by reacting silicic acid with ammonium hydroxide. The eluent is passed through a fluorescence detector, which provides a profile of the fluorescent compounds, and then to a flame ionization detector for analysis of the lipid classes. The method is demonstrated on rat blood serum, liver and kidney tissue.     

Ethyl propionate: Synergistic kairomone for african palm weevil,Rhynchophorus phoenicis L. (Coleoptera: Curculionidae)

Small trunk pieces of a freshly felled 10-year-old oil palm,Elaeis quineensis (Jacq.), were placed in a modified Nalgene desiccator, and volatiles captured for six days on Porapak Q. Gas chromatographic (GC) analysis of Porapak-Q-trapped volatiles with both flame ionization (FID) and electroantennographic detection (EAD) using male or femaleR. phoenicis antennae revealed several EAD-active compounds. They were identified as: ethyl acetate, ethyl propionate, isobutyl propionate, ethyl butyrate, and ethyl isobutyrate. In field experiments in the La Me Research Station, Côte d'Ivoire, ethyl propionate (50 mg/24 hr) but not all esters combined (50 mg/24 hr each) significantly increased capture ofR. phoenicis in pheromone-baited (3 mg/24 hr) traps. One kilogram of 1- to 3-day-old palm tissue was significantly more effective than ethyl propionate in enhancing pheromone attraction. Superior attraction of palm tissue may be attributed to additional as yet unknown semiochemicals. Alternatively, release rates and/or ratios of synthetic volatiles differed from those of palm tissue at peak attraction.     

Fabrication of isocyanate‐based polyimide foam by a postgrafting method

Density and flame retardancy controlled isocyanate‐based polyimide foam was prepared by a postgrafting method. The first solution containing prepolymer that was synthesized by dianhydride and overdose isocyanates was added into the second solution containing dianhydride derivatives, water, catalysts, and surfactants. The possible reactions during preparation are discussed. The obtained Fourier transform infrared spectra indicate that an increased amount of imide rings was generated with increasing molar ratio of the anhydride/isocyanate groups. The size and walls of the cells became smaller and thinner with less carbon dioxide (CO₂) escaping into the air during the first solution preparation process, as shown in scanning electron microscopy images. The thermogravimetric analysis curves demonstrated that the 5% weight loss temperature (T_5%) was greater than 289 °C, and the residual weight retention at 800 °C was more than 45%. In addition, differential thermogravimetry curves demonstrated that the thermal stability decreased with more byproducts in polyimide foams. The limiting oxygen index increased gradually from 30.63% ± 0.56 to 48% ± 0.50 with increasing molar ratio of the anhydride/isocyanate groups. Meanwhile, the density of obtained polyimide foams ranged from 38.31 kg/m³ ± 0.90 to 99.53 kg/m³ ± 10.85. When the molar ratio of anhydride/isocyanate groups ranged from 0.4 to 0.8, the prepared isocyanate‐based polyimide foams all exhibit both great flame retardancy and lower density. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44240.     

Sex pheromone components ofEuxoa drewseni Chemical identification,electrophysiological evaluation,and field attractancy tests

Eleven compounds structurally similar to known lepidopterous pheromone components were identified in the extract from 18 calling female moths ofEuxoa drewseni (Staudinger). The identifications were done by gas chromatography-mass spectrometry and high-resolution gas chromatography with flame ionization and electroantennographic detectors simultaneously. Detector antennae were from five species of moths. In the field, male moths were specifically attracted to a three-component blend of dodecyl, (Z)-5-dodecenyl, and (Z)-7-tetradecenyl acetates in a ratio of 2∶6∶1. This blend at 1000 μg/rubber septum dispenser is recommended as a trap bait for monitoring purposes. Low concentrations of (Z)-7-dodecenyl acetate or (Z)-7-tetradecenol inhibited the attraction of moths to the three-component blend. (Z)-7-Pentadecenyl acetate functioned as a parapheromone in place of (Z)-7-tetradecenyl acetate in the pheromone blend, and they appear to react via the same antennal receptor.     

钢结构用水性膨胀型防火涂料的制备及性能研究

以高岭土及含锆陶瓷纤维作为增强填料,聚醋酸乙烯酯乳胶和醋叔乳胶的混合液为基料,多聚磷酸铵(APP)、三聚氰胺(MEL)、季戊四醇(PER)为膨胀阻燃体系,开发了一种燃烧后具有高强度膨胀炭层的水性膨胀型防火涂料.研究了乳胶类型、膨胀阻燃体系各组分配比、颜基比、高岭土及含锆陶瓷纤维对水性膨胀型防火涂料性能及炭层强度的影响....     

Analysis of exempt paint solvents by gas chromatography using solid-phase microextraction

Acetone, methyl acetate, and parachlorobenzotrifluoride (PCBTF or Oxsol? 100) have been exempted as VOC solvents by the U.S. Environmental Protection Agency. In measuring coating VOC content, separate methods for determining exempt solvents are required. One such method utilizes solid-phase microextraction (SPME) to sample the headspace of solvent-based coatings to which the surrogates acetone-d6, methyl acetate-d3, and/or metachlorobenzotrifluoride have been added. The sampled exempt coating solvents are thermally desorbed and analyzed using gas chromatography with flame ionization or mass spectral detection. The SPME headspace method has also been used to analyze MEK, butyl acetate, tert-butyl acetate, toluene, and xylene in solventborne coatings, and alcohols in waterborne systems. This paper presents the results obtained for acetone and toluene in a large number of aerosol paints. Additionally, the results from a round-robin study for acetone, methyl acetate, and parachlorobenzotrifluoride in commercial solvent-based coatings are reported.     

Quantitative determination of 1,2-diacylglycerol in thoracic aorta of the rat using latroscan TLC/FID: Effect of norepinephrine

This study was undertaken to evaluate the use of the Iatroscan TLC/FID system for quantitating 1,2-diacylglycerol (DG) in the aorta. Cholesteryl acetate was chosen as an internal standard. In order to avoid interference of triglyceride and phospholipids with the separation of the internal standard and 1,2-DG, a stepwise elution of lipids from the silicic acid column was used. The development of Chromarods was done using two solvent systems and a three-step developing technique. Assay and recovery of both 1,2-DG and cholesterol (as compared to cholesteryl acetate) were sufficient to measure changes in the 1,2-DG content in blood vessels. After exposing the thoracic aorta to 10⁻⁵ M norepinephrine for 10 min, the 1,2-DG content increased nearly two-fold without significant change in cholesterol content.     

Polyoxyethylene oligomer distribution of nonionic surfactants

Thin layer chromatography with a flame ionization detection (TLC-FID) technique was applied to the separation and determination of nonionic surfactants containing oxyethylene (OE) chains. The OE adducts with an average number of 4.2, 6.0 and 8.0 oxyethylene units were separated on Chromarod S-II (Silica gel-coated rods) with double development using benzene:ethyl acetate (6:4) and ethyl acetate:acetic acid:water (8:1:1). OE adducts of nonionic surfactants were well separated by the TLC-FID method using simple and standard techniques that eliminate the need for any chemical modification.     

固相萃取辅助提取-气相色谱-质谱分析烟熏腊牛、羊肉挥发性成分

用氮气冲洗、Sep-PakC18固相萃取柱吸附和冷有机溶剂捕集提取烟熏腊牛、羊肉的挥发性成分,用色谱-质谱联用法测定结构,用气相色谱(FID检测器)法进行定量分析。共鉴定出42个化合物,其中17个挥发物是在烟熏腊肉中新鉴定的化合物,这些化合物是:2-乙基苯胺、7,7-二甲基二环[3.3.0]辛烷-2-酮、2-苯基-1-二甲基亚甲基环丙烷、4,5,6,7,8,9-六氢环辛间四烯并呋喃-1(3H)-酮、2-甲基-6-对甲苯基-2-庚烯、法呢醇、十二酸、3-(1,5-二甲基-4-己烯基)-6-亚甲基-1-环己烯、1,2-环氧十六烷、月桂酸酐、2,6-二叔丁基-4-(N,N-二甲氨甲基)酚、2-苯并噻唑啉酮、亚油酸乙酯、亚油酸、乙酸十八醇酯、2,2′-亚甲基双(6-叔丁基-4-甲基)苯酚和3,12-齐墩果烷二酮。     

Fatty acid and sterol synthesis by rat small intestine in vitro

Slices of rat jejunum were incubated with [2-¹⁴C]pyruvate, [1-¹⁴C]acetate, or [³H]H₂O to determine lipogenic activity. Under all conditions studied, pyruvate acted as a better precursor than acetate for fatty acid synthesis but not for the synthesis of sterol. Exogenous glucose significantly (P≤0.05) increased the conversion of both pyruvate and acetate to fatty acids. By contrast, fasting resulted in a decrease (p≤0.05) in lipogenic activity. The highest levels of lipogenesis were observed when [³H]H₂O + glucose at a concentration of 20 mM was used. From such experiments, the absolute rate of fatty acid synthesis in the tissue preparation was calculated: 734±54 nmoles acetyl units incorporated into fatty acids/g tissue/hr.     

Quantitative determination of isomeric glycerides,free fatty acids and triglycerides by thin layer chromatography-flame ionization detector system

Partial glyceride mixtures, which include 1-monoglyceride, 2-monoglyceride, free fatty acid, 1,2-diglyceride, 1,3-diglyceride and triglyceride, could be separated from each other on a 3% boric-acid-impregnated Chromarod S-II (silica gel sintered quartz rod) with either chloroform/acetone (96∶4, v/v) or chloroform/acetone/acetic acid (100∶1∶1, v/v) as the developing solvent mixtures. The components separated on the boric-acid-impregnated rod were automatically quantitated in a hydrogen flame ionization detector (Iatroscan). The relative responses of 1,2-diglyceride, 1,3-diglyceride, free fatty acid and triglyceride were slightly lower than theoretical responses based on weight percentage, whereas 1-monoglyceride and 2-monoglyceride showed slightly higher responses. These responses were converged within a maximal error of 5–10% (SD). Boric-acid-impregnated rods could be used repeatedly, ca. 5 times without any reconditioning procedure. Part of this investigation was reported at the 2nd JOCS-AOCS joint meeting, San Francisco, May 1979.     

Studies in vitro of lipogenesis in rat testicular tissue

Testicular tissue was shown to contain the full complement of enzymes required for de novo synthesis of fatty acids. The enzymes capable of snythesizing palmitic acid from citrate, acetate, or acetyl CoA were found to be present in the soluble (cytoplasmic) fraction. These included fatty acid synthetase, acetyl CoA carboxylase, citrate-cleavage enzyme, malic enzyme, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase. Optimal conditions for assaying activities of fatty acid synthetase and acetyl CoA carboxylase in the soluble fraction from rat testes were established, and the activities of these two enzymes were determined to be 0.54±0.1 and 0.030±0.002 (nmoles of substrate incorporated into fatty acid per min per mg of soluble fraction protein), respectively. The activities of citrate-cleavage enzyme, malic enzyme, and the glucose-6-phosphate dehydrogenase/6-phosphogluconate dehydrogenase pair were also measured. The activities were 6.0±0.7, 34.9±4.2, and 29.9±9.3 nmoles/min/mg, respectively. This study was submitted in partial fulfillment of the requirements for the PhD degree, Department of Biochemistry, Vanderbilt University.     

多功能阻燃剂聚醚多元醇膦酸酯/亚磷酸酯的合成

以丙三醇作为起始剂,三溴苯酚缩水甘油醚、环氧氯丙烷及环氧丙烷为共聚单体,以三氟化硼/四氢呋喃为催化剂合成的阻燃聚醚多元醇作原料,与亚磷酸三甲酯进行酯交换反应和Arbuzov重排反应,合成了新型聚醚多元醇膦酸酯/亚磷酸酯(PEPP)。通过元素分析和IR及1HNMR等分析方法对其化学结构进行了表征。考察了反应物料比对多元醇(HIROL-II)的性能和PEPP应用性能的影响。试验结果表明,适宜的环氧丙烷/环氧氯丙烷/三溴苯酚缩水甘油醚物质的量比是6∶1 1∶1,用23%PEPP制备的聚氨酯泡沫氧指数为31。PEPP是一种热稳定性高、阻燃效果好,同时兼有增塑剂和抗氧剂功能的新型橡塑助剂。     

膨胀型阻燃剂NP430对三元乙丙橡胶阻燃性能的影响

采用膨胀型阻燃剂NP430填充三元乙丙橡胶(EPDM),研究其阻燃性能.结果表明:膨胀型阻燃剂NP430对EPDM具有很好的阻燃效果,外加酸源乙烯-醋酸乙烯共聚物(EVA)和碳源高苯乙烯(HS)树脂具有更好的协同阻燃作用.当EPDM/EVA/HS并用比为80/8.6/11.4、膨胀阻燃剂NP430用量为90份时,极限氧指数可达47.6.填充石蜡油会明显降低EPDM的阻燃性能,但不影响燃烧膨胀过程.而填充少量甲基丙烯酸锌、酚醛树脂等有机填料对EPDM的阻燃性能影响很小;填充炭黑、白炭黑、碳酸钙、可膨胀石墨等无机填料会导致燃烧产生的气体逸出,严重不利于膨胀过程,导致膨胀型阻燃剂不能发挥阻燃作用.     

Qualitative and quantitative analysis of lipoxygenase products in bovine corneal epithelium by liquid chromatography-mass spectrometry with an ion trap

Electrospray ionization ion trap mass spectra of 5-, 12-, and 15-hydroperoxyeicosatetraenoic (HPETE), hydroxyeicosatetraenoic (HETE), and ketoeicosatetraenoic (KETE) acids were recorded. The HPETE were partly dehydrated to the corresponding KETE in the heated capillary of the mass spectrometer. 12-HPETE and 15-HPETE were also converted to KETE by collision-induced dissociation (CID) in the ion trap, whereas CID of 5-HPETE yielded little formation of 5-KETE. Subcellular fractions of bovine corneal epithelium were incubated with arachidonic acid (AA) and the metabolites were analyzed. 15-HETE and 12-HETE were consistently formed, whereas significant accumulation of HPETE and KETE was not detected. Biosynthesis of 12- and 15-HETE was quantified with octadeuterated 12-HETE and 15-HETE as internal standards. The average biosynthesis of 15-HETE and 12-HETE from 30μM AA by the cytosol was 38±8 and below 3 ng/mg protein/30 min, respectively, which increased to 78±21 and 10±4 ng/mg protein/30 min in the presence of 1 mM free Ca²⁺. The microsomal biosynthesis was unaffected by Ca²⁺. The microsomes metabolized AA to 15-HETE as the main metabolite at a low protein concentration (0.3 mg/mL), whereas 12-HETE and 15-HETE were formed in a 2∶1 ratio at a combined rate of 0.7±0.2 μg/mg protein/30 min at a high protein concentration (1.8 mg/mL). The level of 12-HETE in corneal epithelial cells was 50±13 pg/mg tissue, whereas the endogenous amount of 15-HETE was low or undetectable (<3 pg/mg tissue). Incubation of corneas for 20 min at 37°C before processing selectively increased the amounts of 12-HETE in the epithelium fourfold to ∼0.2 ng/mg tissue. We conclude that 12-HETE is the main endogenously formed lipoxygenase product of bovine corneal epithelium.     

Experimental design of the kinetic resolution of a key precursor of high‐value bioactive myo‐inositols by an immobilized lipase

BACKGROUND: The response surface methodology was successfully applied to the optimization of the reaction variables for the kinetic resolution of a precursor of high‐value myo‐inositols, ( ± )‐1,2‐O‐isopropylidene‐3,6‐di‐O‐benzyl‐myo‐inositol (( ± )‐1), by Novozym 435. The resolutions were run separately, with two acylating agents, ethyl acetate and vinyl acetate, in a solvent‐free system. The variables analyzed were reaction temperature, substrate concentration, water concentration and enzyme activity. A statistical model was employed for the evaluation of the influence of the variables on conversion and enantiomeric excess (ee). RESULTS: The optimal conditions for this resolution using vinyl acetate as acylating agent were 45 °C, 5 mg mL^?1 of substrate, 71 U of enzyme activity and 0%w/w of water concentration. The high conversion (49.2 %) and ee (>99%) reached in the chemoenzymatic synthesis of acylated product, L‐(?)‐5‐O‐Acetyl‐3,6‐di‐O‐benzyl‐1,2‐O‐isopropylidene‐myo‐inositol, secure the efficient synthesis of the D enantiomorph present in the original racemic mixture (( ± )‐1) as well. CONCLUSIONS: The use of the experimental design strategy was productive, leading to a 14‐fold increase in the productivity of the reaction compared with the non‐optimized conditions. Both derivative L‐(?)‐2 and remaining substrate D‐(+)‐1 were obtained at high ee. © 2012 Society of Chemical Industry     

凉味剂3-L-薄荷氧基丙烷-1,2-二醇的合成研究

采用一种新方法,通过开环、水解两步反应合成了3-L-薄荷氧基丙烷-1,2-二醇凉味剂。首先用乙酸环氧丙醇酯与薄荷脑在路易斯酸催化作用下进行开环反应得到1-乙酰氧基-3-L-薄荷氧基丙烷-2-醇。开环的最佳条件为:三氟化硼乙醚为催化剂,反应温度0~10°C,反应时间4 h,薄荷脑与乙酸环氧丙醇酯摩尔比1.2∶1.0,催化剂与乙酸环氧丙醇酯摩尔比0.04∶1.0,收率70.5%。1-乙酰氧基-3-L-薄荷氧基丙烷-2-醇经NaOH水解得产物,在此反应中加入甲苯为溶剂,使反应易操作,收率为95.5%。并通过MS和1H NMR确定中间体和产物的结构。     

立构嵌段聚丁二烯的研制Ⅳ．立构二嵌段与三嵌段共混聚丁二烯的研究

在以ｎ－Ｂｕｌｉ为引发剂，环己烷为溶剂，二哌啶乙烷和二乙基锌为调节剂的丁二烯负离子聚合过程中，采用高分子设计，分别以二甲基二氯硅烷、苯甲酸乙酯和乙酸乙酯为偶联剂，合成了不同分子量、不同嵌段比及共混比的１，４－１，２／１，４－１，２－１，４及１，２－１，４／１，２－１，４－１，２立构嵌段聚丁二烯（ＰＢ），考察了共混物的微观相分离、流变性及屈服强度。结果表明，嵌段共混ＰＢ的分子量、嵌段比、共混比值只有在一定范围时，共混物才产生微观相分离，分相的嵌段共混ＰＢ具有较好的流变性、加工性，较小的冷流性和较高的屈服强度。     

Determination of individual long-chain fatty acyl-CoA esters in heart and skeletal muscle

A method has been developed for determination of individual long-chain fatty acyl-CoA esters from heart and skeletal muscle using high performance liquid chromatography (HPLC). The esters were extracted from freezeclamped tissue of pig and rat hearts and rat skeletal muscle for analysis on a radially compressed C₁₈ 5μ reversephase column. Nine peaks in the extract with carbon chain lengths from C₁₂ to C₂₀ that subsequently disappeared on alkaline hydrolysis were identified. The major acyl-CoA peaks were 14∶1, 18∶2, 16∶0 and 18∶1 and additionally in rat heart 18∶0. Total long-chain acyl-CoA esters obtained by summation of the individual molecular species was 11.34±1.48 nmol/g wet wt. pig heart; 14.51±2.11 nmol/g wet wt. in rat heart, and 4.35±0.71 nmol/g wet wt. in rat skeletal muscle. These values were approximately 132% of those obtained using a separate procedure that measured total CoA by HPLC after alkaline hydrolysis of the esters. The described method demonstrates the quantitation of individual acyl-CoA species in muscle tissue. Therefore, it has a number of advantages in that it permits information to be obtained on the individual molecular species under various nutritional and metabolic conditions.