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Sample records for 3-mcpd ester formation

  1. Mechanism of formation of 3-chloropropan-1,2-diol (3-MCPD) esters under conditions of the vegetable oil refining.

    PubMed

    Šmidrkal, Jan; Tesařová, Markéta; Hrádková, Iveta; Berčíková, Markéta; Adamčíková, Aneta; Filip, Vladimír

    2016-11-15

    3-MCPD esters are contaminants that can form during refining of vegetable oils in the deodorization step. It was experimentally shown that their content in the vegetable oil depends on the acid value of the vegetable oil and the chloride content. 3-MCPD esters form approximately 2-5 times faster from diacylglycerols than from monoacylglycerols. It has been proved that the higher fatty acids content in the oil caused higher 3-MCPD esters content in the deodorization step. Neutralization of free fatty acids in the vegetable oil before the deodorization step by alkaline carbonates or hydrogen carbonates can completely suppress the formation of 3-MCPD esters. Potassium salts are more effective than sodium salts. PMID:27283615

  2. Optimization of palm oil physical refining process for reduction of 3-monochloropropane-1,2-diol (3-MCPD) ester formation.

    PubMed

    Zulkurnain, Musfirah; Lai, Oi Ming; Tan, Soo Choon; Abdul Latip, Razam; Tan, Chin Ping

    2013-04-01

    The reduction of 3-monochloropropane-1,2-diol (3-MCPD) ester formation in refined palm oil was achieved by incorporation of additional processing steps in the physical refining process to remove chloroester precursors prior to the deodorization step. The modified refining process was optimized for the least 3-MCPD ester formation and acceptable refined palm oil quality using response surface methodology (RSM) with five processing parameters: water dosage, phosphoric acid dosage, degumming temperature, activated clay dosage, and deodorization temperature. The removal of chloroester precursors was largely accomplished by increasing the water dosage, while the reduction of 3-MCPD esters was a compromise in oxidative stability and color of the refined palm oil because some factors such as acid dosage, degumming temperature, and deodorization temperature showed contradictory effects. The optimization resulted in 87.2% reduction of 3-MCPD esters from 2.9 mg/kg in the conventional refining process to 0.4 mg/kg, with color and oil stability index values of 2.4 R and 14.3 h, respectively. PMID:23464796

  3. Relative oral bioavailability of 3-MCPD from 3-MCPD fatty acid esters in rats.

    PubMed

    Abraham, Klaus; Appel, Klaus E; Berger-Preiss, Edith; Apel, Elisabeth; Gerling, Susanne; Mielke, Hans; Creutzenberg, Otto; Lampen, Alfonso

    2013-04-01

    In order to quantify the relative oral bioavailability of 3-chloropropane-1,2-diol (3-MCPD) from 3-MCPD fatty acid diesters in vivo, 1,2-dipalmitoyl-3-chloropropane-1,2-diol (3-MCPD diester) and 3-MCPD were orally applied to rats in equimolar doses. In both cases, the time courses of 3-MCPD concentrations were measured in blood, various organs, tissues and intestinal luminal contents. The results show that 3-MCPD is released by enzymatic hydrolysis from the 3-MCPD diester in the gastrointestinal tract and distributed to blood, organs and tissues. Based on the measurements in blood, the areas under the curve (AUC) for 3-MCPD were calculated. By comparing both AUC, the relative amount of 3-MCPD bioavailable from the 3-MCPD diester was calculated to be 86 % on average of the amount bioavailable following administration of 3-MCPD. In view of limited experimental data, it is justified for the purpose of risk assessment to assume complete hydrolysis of the diesters in the gastro-intestinal tract. Therefore, assessment of the extent of exposure to 3-MCPD released from its fatty acid esters should be performed in the same way as exposure to the same molar quantity of 3-MCPD. PMID:23229518

  4. Study on the thermal degradation of 3-MCPD esters in model systems simulating deodorization of vegetable oils.

    PubMed

    Ermacora, Alessia; Hrncirik, Karel

    2014-05-01

    The establishment of effective strategies for the mitigation of 3-MCPD esters in refined vegetable oils is restricted by limited knowledge of their mechanisms of formation and decomposition. In order to gain better understanding on the thermal stability of these compounds, a model system for mimicking oil refining conditions was developed. Pure 3-MCPD esters (3-MCPD dipalmitate and 3-MCPD dilaurate) were subjected to thermal treatment (180-260°C) and the degradation products where monitored over time (0-24h). After 24h of treatment, both 3-MCPD esters showed a significant degradation (ranging from 30% to 70%), correlating with the temperature applied. The degradation pathway, similar for both compounds, was found to involve isomerisation (very rapid, equilibrium was reached within 2h at 260°C), dechlorination and deacylation reactions. The higher relative abundance of non-chlorinated compounds, namely acylglycerols, in the first stages of the treatment suggested that dechlorination is preferred over deacylation with the conditions applied in this study. PMID:24360433

  5. Free radical mediated formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters.

    PubMed

    Zhang, Xiaowei; Gao, Boyan; Qin, Fang; Shi, Haiming; Jiang, Yuangrong; Xu, Xuebing; Yu, Liangli Lucy

    2013-03-13

    The present study was conducted to test the hypothesis that a free radical was formed and mediated the formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters, a group of food contaminants, from diacylglycerols at high temperature under a low-moisture condition for the first time. The presence of free radicals in a vegetable oil kept at 120 °C for 20 min was demonstrated using an electron spin resonance (ESR) spectroscopy examination with 5,5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. ESR investigation also showed an association between thermal treatment degree and the concentration of free radicals. A Fourier transform infrared spectroscopy (FT-IR) analysis of sn-1,2-stearoylglycerol (DSG) at 25 and 120 °C suggested the possible involvement of an ester carbonyl group in forming 3-MCPD diesters. On the basis of these results, a novel free radical mediated chemical mechanism was proposed for 3-MCPD diester formation. Furthermore, a quadrupole-time of flight (Q-TOF) MS/MS investigation was performed and detected the DMPO adducts with the cyclic acyloxonium free radical (CAFR) and its product MS ions, proving the presence of CAFR. Furthermore, the free radical mechanism was validated by the formation of 3-MCPD diesters through reacting DSG with a number of organic and inorganic chlorine sources including chlorine gas at 120 and 240 °C. The findings of this study might lead to the improvement of oil and food processing conditions to reduce the level of 3-MCPD diesters in foods and enhance food safety. PMID:23425600

  6. Occurrence of fatty acid esters of 3-MCPD, 2-MCPD and glycidol in infant formula.

    PubMed

    Wöhrlin, Friederike; Fry, Hildburg; Lahrssen-Wiederholt, Monika; Preiß-Weigert, Angelika

    2015-01-01

    The discovery of fatty acid esters of monochloropropanediol (MCPD) and glycidol generated during the refinement process in vegetable fats and oils caused concerns about possible adverse health effects. As these fats are components of infant formula, the current investigation of the MCPD and glycidyl ester contents in infant formula was necessary to update the data for risk assessment purposes. For the analysis of 3-MCPD, 2-MCPD and glycidyl esters in infant formula, an existing method for fats and oils had to be modified and validated. The fat fraction containing MCPD and glycidyl esters was extracted from infant formula by accelerated solvent extraction (ASE). The extracted fat was then analysed according to an established method for fats and oils. Glycidyl esters are converted to monobrompropanediol (3-MBPD) esters, MCPD and 3-MBPD esters hydrolysed subsequently and after derivatisation detected by GC-MS. Seven different products of infant formula, covering two types and five lots each, altogether 70 samples, were bought in retail markets and analysed. In all samples, 3-MCPD and glycidyl esters could be detected. Both 3-MCPD and glycidyl esters' concentration levels were found to be lower in comparison with earlier investigations described in the literature. The occurrence of 2-MCPD esters in infant formula was investigated for the first time and revealed concentrations about half of 3-MCPD ester concentrations. PMID:26179516

  7. Influence of dough ingredients on 3-chloropropane-1,2-diol (3-MCPD) formation in toast.

    PubMed

    Breitling-Utzmann, C M; Hrenn, H; Haase, N U; Unbehend, G M

    2005-02-01

    The influence of different dough ingredients such as fat, salt, sourdough, emulsifiers, and sugar on the formation of 3-chloropropane-1,2-diol (3-MCPD) during toast preparation under domestic conditions was investigated. In comparison with a fat-free recipe, addition of 1% peanut fat considerably increased 3-MCPD formation, but varying the fat (2-5%) or salt (1.6-2.4%) contents within technological acceptable limits did not show any significant differences. A baking agent, which is usually commercially applied by many toast bakers or industrial toast manufacturers, increased 3-MCPD formation in toasted bread slices. Considerable evidence was found that the baking agent's main component sucrose had the major part in increasing 3-MCPD levels. Emulsifiers containing monoacylglycerols moderately increased 3-MCPD levels, but the addition of lecithin did not have any significant influence. 3-MCPD levels showed a good correlation with the lightness (L* value) of the bread slices; their 3-MCPD content increased exponentially towards dark coloured toasts. The relation between 3-MCPD and 2-MCPD was an average of 3:1 in all samples. Dichloropropanols such as, for example, 1,3-dichloropropanol could not be detected. PMID:15823998

  8. Collaborative Study of an Indirect Enzymatic Method for the Simultaneous Analysis of 3-MCPD, 2-MCPD, and Glycidyl Esters in Edible Oils.

    PubMed

    Koyama, Kazuo; Miyazaki, Kinuko; Abe, Kousuke; Egawa, Yoshitsugu; Kido, Hirotsugu; Kitta, Tadashi; Miyashita, Takashi; Nezu, Toru; Nohara, Hidenori; Sano, Takashi; Takahashi, Yukinari; Taniguchi, Hideji; Yada, Hiroshi; Yamazaki, Kumiko; Watanabe, Yomi

    2016-07-01

    A collaborative study was conducted to evaluate an indirect enzymatic method for the analysis of fatty acid esters of 3-monochloro-1,2-propanediol (3-MCPD), 2-monochloro-1,3-propanediol (2-MCPD), and glycidol (Gly) in edible oils and fats. The method is characterized by the use of Candida rugosa lipase, which hydrolyzes the esters at room temperature in 30 min. Hydrolysis and bromination steps convert esters of 3-MCPD, 2-MCPD, and glycidol to free 3-MCPD, 2-MCPD, and 3-monobromo-1,2-propanediol, respectively, which are then derivatized with phenylboronic acid, and analyzed by gas chromatography-mass spectrometry. In a collaborative study involving 13 laboratories, liquid palm, solid palm, rapeseed, and rice bran oils spiked with 0.5-4.4 mg/kg of esters of 3-MCPD, 2-MCPD, and Gly were analyzed in duplicate. The repeatability (RSDr) were < 5% for five liquid oil samples and 8% for a solid oil sample. The reproducibility (RSDR) ranged from 5% to 18% for all oil samples. These RSDR values were considered satisfactory because the Horwitz ratios were ≤ 1.3% for all three analytes in all oil samples. This method is applicable to the quantification of 3-MCPD, 2-MCPD, and Gly esters in edible oils. PMID:27321120

  9. Proteomic analysis of 3-MCPD and 3-MCPD dipalmitate-induced toxicity in rat kidney.

    PubMed

    Sawada, Stefanie; Oberemm, Axel; Buhrke, Thorsten; Merschenz, Julia; Braeuning, Albert; Lampen, Alfonso

    2016-06-01

    3-Chloropropane-1,2-diol (3-MCPD) and its fatty acid esters are formed during thermal treatment of fat-containing foodstuff in the presence of salt. Toxicological studies indicate a carcinogenic potential of 3-MCPD, pointing to the kidney as the main target organ. It is assumed that the toxicological property of 3-MCPD esters is constituted by the release of 3-MCPD during digestion. In a repeated-dose 28-day oral toxicity study using Wistar rats, animals were treated with equimolar doses of either 3-MCPD (10 mg/kg body weight) or 3-MCPD dipalmitate (53 mg/kg body weight). A lower dose of 3-MCPD dipalmitate (13.3 mg/kg body weight) was also applied. No histopathologically visible toxicity was observed in the study. To address molecular mechanisms leading to toxicity of 3-MCPD and its esters, kidney samples were analyzed by a comparative, two-dimensional gel electrophoresis/mass spectrometry proteomic approach. After either 3-MCPD or 3-MCPD dipalmitate treatment, alterations in proteins related to various metabolic pathways, including carbohydrate, amino acid, and fatty acid metabolism, were detected. These findings confirm and complement previous data on the inhibition of glucose metabolism by 3-MCPD. Altogether, broad overlap of 3-MCPD- and 3-MCPD dipalmitate-induced proteomic changes was observed. Further analyses revealed that the observed induction of glutathione S-transferase pi 1 (Gstp1) occurred at the transcriptional level and was not related to nuclear factor (erythroid-derived 2)-like 2 activation. Overall, the results indicate common mechanisms of toxicity for 3-MCPD and its dipalmitate ester. Furthermore, data suggest Gstp1 as a sensitive marker for early 3-MCPD-induced effects in rat kidney. PMID:26253146

  10. Preparation of five 3-MCPD fatty acid esters and the effects of their chemical structures on acute oral toxicity in Swiss mice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fatty acid esters of 3-monochloro-1, 2-propanediol (3-MCPDEs), including 1-stearic, 1-oleic, 1-linoleic, 1-linoleic-2-palmitic and 1-palmitic-2-linoleic acid esters, were synthetized and examined for their acute oral toxicities in Swiss mice. 3-MCPDEs were obtained through the reaction of 3-MCPD and...

  11. Formation and reduction of 3-monochloropropane-1,2-diol esters in peanut oil during physical refining.

    PubMed

    Li, Chang; Li, Linyan; Jia, Hanbing; Wang, Yuting; Shen, Mingyue; Nie, Shaoping; Xie, Mingyong

    2016-05-15

    In the present study, lab-scale physical refining processes were investigated for their effects on the formation of 3-monochloropropane-1,2-diol (3-MCPD) esters. The potential precursors, partial acylglycerols and chlorines were determined before each refining step. 3-MCPD esters were not detected in degummed and bleached oil when the crude oils were extracted by solvent. While in the hot squeezed crude oils, 3-MCPD esters were detected with low amounts. 3-MCPD esters were generated with maximum values in 1-1.5h at a certain deodorizing temperature (220-260°C). Chlorine seemed to be more effective precursor than partial acylglycerol. By washing bleached oil before deodorization with ethanol solution, the precursors were removed partially and the content of 3-MCPD esters decreased to some extent accordingly. Diacetin was found to reduce 3-MCPD esters effectively. PMID:26776014

  12. The effects of physical refining on the formation of 3-monochloropropane-1,2-diol esters in relation to palm oil minor components.

    PubMed

    Zulkurnain, Musfirah; Lai, Oi Ming; Latip, Razam Abdul; Nehdi, Imededdine Arbi; Ling, Tau Chuan; Tan, Chin Ping

    2012-11-15

    The formation of 3-monochloropropane-1,2-diol (3-MCPD) esters in refined palm oil during deodorisation is attributed to the intrinsic composition of crude palm oil. Utilising D-optimal design, the effects of the degumming and bleaching processes on the reduction in 3-MCPD ester formation in refined palm oil from poor-quality crude palm oil were studied relative to the palm oil minor components that are likely to be their precursors. Water degumming remarkably reduced 3-MCPD ester formation by up to 84%, from 9.79 mg/kg to 1.55 mg/kg. Bleaching with synthetic magnesium silicate caused a further 10% reduction, to 0.487 mg/kg. The reduction in 3-MCPD ester formation could be due to the removal of related precursors prior to the deodorisation step. The phosphorus content of bleached palm oil showed a significant correlation with 3-MCPD ester formation. PMID:22868161

  13. Antioxidants Inhibit Formation of 3-Monochloropropane-1,2-diol Esters in Model Reactions.

    PubMed

    Li, Chang; Jia, Hanbing; Shen, Mingyue; Wang, Yuting; Nie, Shaoping; Chen, Yi; Zhou, Yongqiang; Wang, Yuanxing; Xie, Mingyong

    2015-11-11

    The capacities of six antioxidants to inhibit the formation of 3-monochloropropane-1,2 diol (3-MCPD) esters were examined in this study. Inhibitory capacities of the antioxidants were investigated both in chemical models containing the precursors (tripalmitoyl glycerol, 1,2-dipalmitoyl-sn-glycerol, monopalmitoyl glycerol, and sodium chloride) of 3-MCPD esters and in oil models (rapeseed oil and sodium chloride). Six antioxidants, butylated hydroxytoluene (BHT), butylated hydroxy anisole (BHA), tert-butyl hydroquinone (TBHQ), propyl gallate (PG), L-ascorbyl palmitate (AP), and α-tocopherol (VE), were found to exhibit inhibiting capacities on 3-MCPD ester formation both in chemical models and in oil models. TBHQ provided the highest inhibitory capacity both in chemical models and in oil models; 44% of 3-MCPD ester formation was inhibited in the presence of TBHQ (66 mg/kg of oil) after heating of rapeseed oil at 230 °C for 30 min, followed by PG and AP. BHT, BHA, and VE appeared to have weaker inhibitory abilities in both models. VE exhibited the lowest inhibition rate; 22% of 3-MCPD esters were inhibited in the presence of VE (172 mg/kg of oil) after heating of rapeseed oil at 230 °C for 30 min. In addition, the inhibition rates of PG and VE decreased dramatically with an increase in temperature or heating time. The results suggested that some antioxidants, such as TBHQ, PG, and AP, could be the potential inhibitors of 3-MCPD esters in practice. PMID:26478126

  14. Other factors to consider in the formation of chloropropandiol fatty esters in oil processes.

    PubMed

    Ramli, Muhamad Roddy; Siew, Wai Lin; Ibrahim, Nuzul Amri; Kuntom, Ainie; Abd Razak, Raznim Arni

    2015-01-01

    This paper examines the processing steps of extracting palm oil from fresh fruit bunches in a way that may impact on the formation of chloropropandiol fatty esters (3-MCPD esters), particularly during refining. Diacylglycerols (DAGs) do not appear to be a critical factor when crude palm oils are extracted from various qualities of fruit bunches. Highly hydrolysed oils, in spite of the high free fatty acid (FFA) contents, did not show exceptionally high DAGs, and the oils did not display a higher formation of 3-MCPD esters upon heat treatment. However, acidity measured in terms of pH appears to have a strong impact on 3-MCPD ester formation in the crude oil when heated at high temperatures. The differences in the extraction process of crude palm oil from current commercial processes and that from a modified experimental process showed clearly the effect of acidity of the oil on the formation of 3-MCPD esters. This paper concludes that the washing or dilution step in palm oil mills removes the acidity of the vegetative materials and that a well-optimised dilution/washing step in the extraction process will play an important role in reducing formation of 3-MCPD esters in crude palm oil upon further heat processing. PMID:25798697

  15. 3-MCPD: A Worldwide Problem of Food Chemistry.

    PubMed

    Jędrkiewicz, Renata; Kupska, Magdalena; Głowacz, Agnieszka; Gromadzka, Justyna; Namieśnik, Jacek

    2016-10-25

    3-Monochloropropane-1,2-diol (3-MCPD) is a heat-induced food contaminant that has been widely investigated for decades. This paper presents an overview of current knowledge about 3-MCPD, including its formation routes, occurrence in various foodstuffs, analytical approach, toxicological aspects, and future research perspectives. So far, 3-MCPD was determined in its free and bound form in thermally treated foods, edible oils and fats, and infant foods including human breast milk. Contaminants in infant foods and human breast milk were highlighted in this paper as a serious problem as they can pose a potential hazard for infants. The analytical approach of 3-MCPD determination has been modified for over a decade. Nowadays, the method based on determining the derivative of this compound by using gas chromatography and mass spectrometry is widely used. However, there is still a big need for developing new methods that would produce repeatable results. Some of the toxicologic aspects associated with 3-MCPD still remain unknown. A number of studies on the carcinogenicity and genotoxicity of 3-MCPD were carried out on rodents; however, no clinical studies on humans have been reported so far. Moreover, both detrimental effect on kidneys and antifertility activity have been widely reported. The knowledge of 3-MCPD absorption into body fluids and tissues and its metabolic pathways is based on sometimes conflicting data derived from different studies. In conclusion, although a lot of research has been carried out on 3-MCPD, there is still a need for further research in this area. PMID:25830907

  16. 3-MCPD 1-palmitate induced renal tubular cell apoptosis in vivo via JNK/p53 pathway

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fatty acid esters of 3-chloro-1, 2-propanediol (3-MCPD esters) are a group of processing-induced food contaminants with nephrotoxicity, but the molecular mechanism(s) remains unclear. This study investigated whether and how the JNK/p53 pathway may play a role in the nephrotoxic effect of 3-MCPD este...

  17. Mitigation of 3-Monochloro-1,2-propanediol Ester Formation by Radical Scavengers.

    PubMed

    Zhang, Hai; Jin, Pengwei; Zhang, Min; Cheong, Ling-Zhi; Hu, Peng; Zhao, Yue; Yu, Liangli; Wang, Yong; Jiang, Yuanrong; Xu, Xuebing

    2016-07-27

    The present study investigated the possible mechanism of free radical scavengers on mitigation of 3-monochloro-1,2-propanediol (3-MCPD) fatty acid ester formation in vegetable oils. The electron spin resonance investigation showed that the concentration of free radicals could be clearly decreased in 1,2-distearoyl-sn-glycerol (DSG) samples by all four antioxidants (l-ascorbyl palmitate, α-tocopherol, lipophilic tea polyphenols, and rosemary extract) at 120 °C for 20 min under a N2 atmosphere. Moreover, the rosemary extract exhibited the highest inhibition efficiency. The Fourier transform infrared spectroscopy examination of DSG with α-tocopherol at 25 and 120 °C revealed that α-tocopherol could prevent the involvement of an ester carbonyl group of DSG in forming the cyclic acyloxonium free radical intermediate. Furthermore, the ultraperformance liquid chromatography-quadrupole-time-of-flight mass spectrometry analysis showed that α-tocopherol could suppress the formation of 3-MCPD di- and monoesters. Finally, the four antioxidants could decrease 3-MCPD esters in the palm oil during deodorization. Particularly, the rosemary extract also showed the highest efficiency in 3-MCPD ester mitigation. PMID:27396990

  18. Analysis of 3-MCPD and 1,3-DCP in Various Foodstuffs Using GC-MS

    PubMed Central

    Kim, Wooseok; Jeong, Yun A; On, Jiwon; Choi, Ari; Lee, Jee-yeon; Lee, Joon Goo; Lee, Kwang-Geun

    2015-01-01

    3-Monochloro-1,2-propanediol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) are not only produced in the manufacturing process of foodstuffs such as hydrolyzed vegetable proteins and soy sauce but are also formed by heat processing in the presence of fat and low water activity. 3-MCPD exists both in free and ester forms, and the ester form has been also detected in various foods. Free 3-MCPD and 1,3-DCP are classified as Group 2B by the International Agency for Research on Cancer. Although there is no data confirming the toxicity of either compound in humans, their toxicity was evidenced in animal experimentation or in vitro. Although few studies have been conducted, free 3-MCPD has been shown to have neurotoxicity, reproductive toxicity, and carcinogenicity. In contrast, 1,3-DCP only has mutagenic activity. The purpose of this study was to analyze 3-MCPD and 1,3-DCP in various foods using gas chromatography -mass spectrometry. 3-MCPD and 1,3-DCP were analyzed using phenyl boronic acid derivatization and the liquid–liquid extraction method, respectively. The analytical method for 3-MCPD and 1,3-DCP was validated in terms of linearity, limit of detection (LOD), limit of quantitation, accuracy and precision. Consequently, the LODs of 3-MCPD and 1,3-DCP in various matrices were identified to be in the ranges of 4.18~10.56 ng/g and 1.06~3.15 ng/g, respectively. PMID:26483891

  19. Analysis of 3-MCPD and 1,3-DCP in Various Foodstuffs Using GC-MS.

    PubMed

    Kim, Wooseok; Jeong, Yun A; On, Jiwon; Choi, Ari; Lee, Jee-Yeon; Lee, Joon Goo; Lee, Kwang-Geun; Pyo, Heesoo

    2015-09-01

    3-Monochloro-1,2-propanediol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) are not only produced in the manufacturing process of foodstuffs such as hydrolyzed vegetable proteins and soy sauce but are also formed by heat processing in the presence of fat and low water activity. 3-MCPD exists both in free and ester forms, and the ester form has been also detected in various foods. Free 3-MCPD and 1,3-DCP are classified as Group 2B by the International Agency for Research on Cancer. Although there is no data confirming the toxicity of either compound in humans, their toxicity was evidenced in animal experimentation or in vitro. Although few studies have been conducted, free 3-MCPD has been shown to have neurotoxicity, reproductive toxicity, and carcinogenicity. In contrast, 1,3-DCP only has mutagenic activity. The purpose of this study was to analyze 3-MCPD and 1,3-DCP in various foods using gas chromatography -mass spectrometry. 3-MCPD and 1,3-DCP were analyzed using phenyl boronic acid derivatization and the liquid-liquid extraction method, respectively. The analytical method for 3-MCPD and 1,3-DCP was validated in terms of linearity, limit of detection (LOD), limit of quantitation, accuracy and precision. Consequently, the LODs of 3-MCPD and 1,3-DCP in various matrices were identified to be in the ranges of 4.18~10.56 ng/g and 1.06~3.15 ng/g, respectively. PMID:26483891

  20. 3-MCPD 1-Palmitate Induced Tubular Cell Apoptosis In Vivo via JNK/p53 Pathways.

    PubMed

    Liu, Man; Huang, Guoren; Wang, Thomas T Y; Sun, Xiangjun; Yu, Liangli Lucy

    2016-05-01

    Fatty acid esters of 3-chloro-1, 2-propanediol (3-MCPD esters) are a group of processing induced food contaminants with nephrotoxicity but the molecular mechanism(s) remains unclear. This study investigated whether and how the JNK/p53 pathway may play a role in the nephrotoxic effect of 3-MCPD esters using 3-MCPD 1-palmitate (MPE) as a probe compound in Sprague Dawley rats. Microarray analysis of the kidney from the Sprague Dawley rats treated with MPE, using Gene Ontology categories and KEGG pathways, revealed that MPE altered mRNA expressions of the genes involved in the mitogen-activated protein kinase (JNK and ERK), p53, and apoptotic signal transduction pathways. The changes in the mRNA expressions were confirmed by qRT-PCR and Western blot analyses and were consistent with the induction of tubular cell apoptosis as determined by histopathological, TUNEL, and immunohistochemistry analyses in the kidneys of the Sprague Dawley rats. Additionally, p53 knockout attenuated the apoptosis, and the apoptosis-related protein bax expression and cleaved caspase-3 activation induced by MPE in the p53 knockout C57BL/6 mice, whereas JNK inhibitor SP600125 but not ERK inhibitor U0126 inhibited MPE-induced apoptosis, supporting the conclusion that JNK/p53 might play a critical role in the tubular cell apoptosis induced by MPE and other 3-MCPD fatty acid esters. PMID:27008853

  1. Exposure assessment of 3-monochloropropane-1, 2-diol esters from edible oils and fats in China.

    PubMed

    Li, Chang; Nie, Shao-Ping; Zhou, Yong-Qiang; Xie, Ming-Yong

    2015-01-01

    3-monochoropropane-1, 2-diol (3-MCPD) esters from edible oils are considered to be a possible risk factor for adverse effects in human. In the present study, the exposure assessment of 3-MCPD esters to Chinese population was performed. A total of 143 edible oil and fat samples collected from Chinese markets were determined for the concentrations of 3-MCPD esters. The concentration data together with the data of fats consumed were analyzed by the point evaluation and probabilistic assessment for the exposure assessment. The point evaluation showed that the mean daily intake (DI) of 3-MCPD esters were lower than the value of provisional maximum tolerable daily intake (PMTDI) of 3-MCPD (2 µg/kg BW/d). The mean DI values in different age groups obtained from probabilistic assessment were similar to the results of the point evaluation. However, in high percentiles (95th, 97.5th, 99th), the DI values in all age groups were undesirably higher than the value of PMTDI. Overall, the children and adolescents exposed more to 3-MCPD esters than the adults. Uncertainty was also analyzed for the exposure assessment. Decreasing the level of 3-MCPD esters in edible oils and consuming less oil were top priority to minimize the risk of 3-MCPD esters. PMID:25447762

  2. 3-Monochloro-1,2-propandiol (3-MCPD) in soy sauce from the Bulgarian market.

    PubMed

    Christova-Bagdassarian, Valentina; Tishkova, Julieta A; Vrabcheva, Terry M

    2013-01-01

    The 3-monochloro-1,2-propandiol (3-MCPD) levels in soy sauces which contained hydrolysed vegetable protein were evaluated for the Bulgarian market. For analysis of 3-MCPD, a gas chromatography-mass spectrometry (GC-MS) method was applied with a linear range of 0.03-2.00 μg mL⁻¹ and a limit of detection (LOD) of 2.3 μg kg⁻¹ and a limit of quantification (LOQ) of 3.4 μg kg⁻¹. At these levels, the standard deviation was 5.1%, with recoveries between 81% and 102%. The method was applied to the analysis of 21 samples of soy sauce from the Bulgarian market. Results ranged from 3.7 to 185.6 μg kg⁻¹. Soy sauces produced from hydrolysed soy protein contained higher levels of 3-MCPD than naturally fermented sauces. In 38.4% of samples of Bulgarian origin, the 3-MCPD content was above the EU limit of 20 μg kg⁻¹. In all analysed samples, 33.3% had a 3-MCPD content above the EU limit. PMID:24779899

  3. Analysis of processing contaminants in edible oils. Part 1. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol monoesters and glycidyl esters.

    PubMed

    MacMahon, Shaun; Mazzola, Eugene; Begley, Timothy H; Diachenko, Gregory W

    2013-05-22

    A new analytical method has been developed and validated for the detection of glycidyl esters (GEs) and 3-monochloropropanediol (3-MCPD) monoesters in edible oils. The target compounds represent two classes of potentially carcinogenic chemical contaminants formed during the processing of edible oils. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Chromatographic conditions that separate sn-1 and sn-2 monoesters of 3-MCPD have been developed for the first time. The method has been validated for GEs, sn-1 3-MCPD monoesters of lauric, myristic, linolenic, linoleic, oleic, and stearic acids, and sn-2 3-MCPD monoesters of oleic and palmitic acids in coconut, olive, and palm oils using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 84-115% (3-16% RSD) for the GEs, 95-113% (1-10% RSD) for the sn-1 3-MCPD monoesters, and 76.8-103% (5.1-11.2% RSD) for the sn-2 3-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the GEs, 60 ng/g for sn-1 3-MCPD monoesters, and 180 ng/g for sn-2 3-MCPD monoesters. PMID:23590632

  4. Estimation of the Intestinal Absorption and Metabolism Behaviors of 2- and 3-Monochloropropanediol Esters.

    PubMed

    Kaze, Naoki; Watanabe, Yomi; Sato, Hirofumi; Murota, Kaeko; Kotaniguchi, Miyako; Yamamoto, Hiroshi; Inui, Hiroshi; Kitamura, Shinichi

    2016-08-01

    The regioisomers of the di- and mono-oleate of monochloropropanediol (MCPD) have been synthesized and subsequently hydrolyzed with pancreatic lipase and pancreatin to estimate the intestinal digestion and absorption of these compounds after their intake. The hydrolysates were analyzed by HPLC using a corona charged aerosol detection system, which allowed for the separation and detection of the different regioisomers of the MCPD esters. The hydrolysates were also analyzed by GC-MS to monitor the free MCPD. The results indicated that the two acyl groups of 2-MCPD-1,3-dioleate were smoothly hydrolyzed by pancreatic lipase and pancreatin to give free 2-MCPD. In contrast, the hydrolysis of 3-MCPD-1,2-dioleate proceeded predominantly at the primary position to produce 3-MCPD-2-oleate. 2-MCPD-1-oleate and 3-MCPD-1-oleate were further hydrolyzed to free 2- and 3-MCPD by pancreatic lipase and pancreatin, although the hydrolysis of 3-MCPD-2-oleate was 80 % slower than that of 3-MCPD-1-oleate. The intestinal absorption characteristics of these compounds were evaluated in vitro using a Caco-2 cell monolayer. The results revealed that the MCPD monooleates, but not the MCPD dioleates, were hydrolyzed to produce the free MCPD in the presence of the Caco-2 cells. The resulting free MCPD permeated the Caco-2 monolayer most likely via a diffusion mechanism because their permeation profiles were independent of the dose. Similar permeation profiles were obtained for 2- and 3-MCPDs. PMID:27023203

  5. Comparison of indirect and direct quantification of esters of monochloropropanediol in vegetable oil.

    PubMed

    Dubois, Mathieu; Tarres, Adrienne; Goldmann, Till; Empl, Anna Maria; Donaubauer, Alfred; Seefelder, Walburga

    2012-05-01

    The presence of fatty acid esters of monochloropropanediol (MEs) in food is a recent concern raised due to the carcinogenicity of their hydrolysable moieties 2- and 3-monochloropropanediol (2- and 3-MCPD). Several indirect methods for the quantification of MEs have been developed and are commonly in use until today, however significant discrepancies among analytical results obtained are challenging their reliability. The aim of the present study was therefore to test the trueness of an indirect method by comparing it to a newly developed direct method using palm oil and palm olein as examples. The indirect method was based on ester cleavage under acidic conditions, derivatization of the liberated 2- and 3-MCPD with heptafluorobutyryl imidazole and GC-MS determination. The direct method was comprised of two extraction procedures targeting 2-and 3-MCPD mono esters (co-extracting as well glycidyl esters) by the use of double solid phase extraction (SPE), and 2- and 3-MCPD di-esters by the use of silica gel column, respectively. Detection was carried out by liquid chromatography coupled to time of flight mass spectrometry (LC-ToF-MS). Accurate quantification of the intact compounds was assured by means of matrix matched standard addition on extracts. Analysis of 22 palm oil and 7 palm olein samples (2- plus 3-MCPD contamination ranged from 0.3 to 8.8 μg/g) by both methods revealed no significant bias. Both methods were therefore considered as comparable in terms of results; however the indirect method was shown to require less analytical standards, being less tedious and furthermore applicable to all type of different vegetable oils and hence recommended for routine application. PMID:22444428

  6. Determination of 3-MCPD by GC-MS/MS with PTV-LV injector used for a survey of Spanish foodstuffs.

    PubMed

    León, Nuria; Yusà, Vicent; Pardo, Olga; Pastor, Agustín

    2008-05-15

    3-Monochloropropane-1,2-diol (3-MCPD) is the most common chemical contaminant of the group of chloropropanols. It can occur in foods and food ingredients at low levels as a result of processing, migration from packaging materials during storage and domestic cooking. A sensitive method for determination of 3-MCPD in foodstuffs using programmable temperature vaporization (PTV) with large-volume injection (LVI) gas chromatography (GC) with tandem mass spectrometry detection (MS/MS) has been developed and optimized. The optimization of the injection and detection parameters was carried out using statistical experimental design. A Plackett-Burman design was used to estimate the influence of resonance excitation voltage (REV), isolation time (IT), excitation time (ET), ion source temperature (IST), and electron energy (EE) on the analytical response in the ion trap mass spectrometer (ITMS). Only REV was found to have a statically significant effect. On the other hand, a central composite design was used to optimize the settings of injection temperature (T(inlet)), vaporization temperature (T(vap)), vaporization time (t(vap)) and flow (Flow). The optimized method has an instrumental limit of detection (signal-to-noise ratio 3:1) of 0.044 ng mL(-1). From Valencian, Spain, supermarkets 94 samples of foods were surveyed for 3-MCPD. Using the optimized method levels higher than the limit established for soy sauce by the European Union were found in some samples. The estimated daily intake of 3-MCPD throughout the investigated foodstuffs for adults and children was found about 0.005 and 0.01%, respectively, of the established provisional tolerable daily intake. PMID:18585153

  7. Regulatory link between steryl ester formation and hydrolysis in the yeast Saccharomyces cerevisiae.

    PubMed

    Ploier, Birgit; Korber, Martina; Schmidt, Claudia; Koch, Barbara; Leitner, Erich; Daum, Günther

    2015-07-01

    Steryl esters and triacylglycerols are the major storage lipids of the yeast Saccharomyces cerevisiae. Steryl esters are formed in the endoplasmic reticulum by the two acyl-CoA:sterol acyltransferases Are1p and Are2p, whereas steryl ester hydrolysis is catalyzed by the three steryl ester hydrolases Yeh1p, Yeh2p and Tgl1p. To shed light on the regulatory link between steryl ester formation and hydrolysis in the maintenance of cellular sterol and free fatty acid levels we employed yeast mutants which lacked the enzymes catalyzing the degradation of steryl esters. These studies revealed feedback regulation of steryl ester formation by steryl ester hydrolysis although in a Δtgl1Δyeh1Δyeh2 triple mutant the gene expression levels of ARE1 and ARE2 as well as protein levels and stability of Are1p and Are2p were not altered. Nevertheless, the capacity of the triple mutant to synthesize steryl esters was significantly reduced as shown by in vitro and in vivo labeling of lipids with [(14)C]oleic acid and [(14)C]acetate. Enzymatic analysis revealed that inhibition of steryl ester formation occurred at the enzyme level. As the amounts and the formation of sterols and fatty acids were also decreased in the triple mutant we concluded that defects in steryl ester hydrolysis also caused feedback inhibition on the formation of sterols and fatty acids which serve as precursors for steryl ester formation. In summary, this study demonstrates a regulatory link within the steryl ester metabolic network which contributes to non-polar lipid homeostasis in yeast cells. PMID:25720564

  8. Simultaneous determination of total fatty acid esters of chloropropanols in edible oils by gas chromatography-mass spectrometry with solid-supported liquid-liquid extraction.

    PubMed

    Liu, Qing; Han, Feng; Xie, Ke; Miao, Hong; Wu, Yongning

    2013-11-01

    This study aimed to establish a novel robust method for the simultaneous determination of total fatty acid esters of 4 chloropropanols including fatty acid esters of 3-monochloropropane-1,2-diol (3-MCPD esters), 2-monochloropropane-1,3-diol (2-MCPD esters), 1,3-dichloropropan-2-ol (1,3-DCP esters) and 2,3-dichloropropan-1-ol (2,3-DCP esters) in edible oils. In this method, sodium methylate in methanol was used as the reagent for the ester cleavage reaction of chloropropanols esters. The reaction products were extracted by a sodium sulfate solution, and then purified by solid-supported liquid-liquid extraction (SLE) using diatomaceous earth (Hydromatrix™) as the sorbent. Finally, the extracts were derivatized with heptafluorobutyrylim idazole (HFBI) and analyzed by gas chromatography-mass spectrometry (GC-MS). Quantification was achieved using deuterated chloropropanols as their respective internal standards, including 3-MCPD-d5, 2-MCPD-d5, 1,3-DCP-d5 and 2,3-DCP-d5. A good linear relationship between peak area and concentrations was obtained within the range of 0.025-2.000mgL(-1) with a correlation coefficients not less than 0.999 for all the chloropropanols esters. The limits of detection (LODs) of esters of 3-MCPD, 2-MCPD, 1,3-DCP and 2,3-DCP (calculated as corresponding chloropropanols) were 30, 30, 100 and 30μgkg(-1), respectively. The average recoveries of the 3-MCPD esters and the 4 chloropropanols spiked at 0.1, 0.5 and 2mgkg(-1) into blank oil matrix were typically in a range from 70.7% to 113.3%. The robust method validation data including calibration, LOD/LOQ, accuracy and repeatability and proficiency test results (Z-score: -0.5) of the official Food Analysis Performance Assessment Scheme (FAPAS) indicated that the present quantitative method could be successfully applied to the determination of total chloropropanols esters in various edible oils. PMID:24070627

  9. Sphingosine inhibits sphingomyelinase-induced cholesteryl ester formation in cultured fibroblasts.

    PubMed

    Härmälä, A S; Pörn, M I; Slotte, J P

    1993-12-01

    We have in this study examined the effects of sphingosine, a possible secondary degradation product following sphingomyelin hydrolysis, on cholesterol homeostasis in cultured human fibroblasts treated with sphingomyelinase. The activation of cholesterol esterification, which resulted from the degradation of plasma membrane sphingomyelin (by sphingomyelinase), was observed to be effectively blocked by sphingosine (half-maximal dose 6-7 microM). The inhibitory action of sphingosine could not be reproduced with other amines (e.g., dodecyl amine or imipramine). The onset of inhibition of cholesteryl ester formation by sphingosine was rapid (maximal effect within 15 min). Sphingosine itself had no spontaneous effects on the distribution of cellular cholesterol. At concentrations below 10 microM, sphingosine was not cytotoxic, as determined by cellular trypan blue permeability. The inhibitory action of sphingosine on cholesteryl ester formation apparently did not result from a direct inhibition of acyl-CoA cholesterol acyltransferase (ACAT), since the activity of this enzyme was unaffected by sphingosine (10 microM) in a cell-free homogenate, using [14C]oleoyl-CoA as a co-substrate. Sphingosine was also unable to prevent the formation of activated fatty acids (oleoyl-CoA), since acyl-CoA synthetase activity in a cell-free homogenate was not inhibited by sphingosine (at 5 microM). The cellular cholesteryl ester cycle (i.e., the neutral cholesteryl ester hydrolase) was unaffected by sphingosine (at 5 microM). Down-regulation of PKC activity (24 h exposure of cells to 100 nM (62 ng/ml) phorbol ester) did not affect the sphingomyelinase-induced stimulation of [3H]cholesteryl ester formation. In addition, the sphingosine-induced inhibition of [3H]cholesteryl ester formation was not reversed in the presence of phorbol ester (short-term exposures), suggesting that the effect of sphingosine was not mediated via PKC. In conclusion, we have shown that sphingosine is an inhibitor

  10. Tricarballylic ester formation during biosynthesis of fumonisin mycotoxins in Fusarium verticillioides.

    PubMed

    Lia, Yaoyao; Lou, Lili; Cerny, Ronald L; Butchko, Robert A E; Proctor, Robert H; Shen, Yuemao; Du, Liangcheng

    2013-12-01

    Fumonisins are agriculturally important mycotoxins produced by the maize pathogen Fusarium verticillioides. The chemical structure of fumonisins contains two tricarballylic esters, which are rare structural moieties and important for toxicity. The mechanism for the tricarballylic ester formation is not well understood. FUM7 gene of F. verticillioides was predicted to encode a dehydrogenase/reductase, and when it was deleted, the mutant produced tetradehydro fumonisins (DH4-FB). MS and NMR analysis of DH4-FB1 indicated that the esters consist of aconitate with a 3'-alkene function, rather than a 2'-alkene function. Interestingly, the purified DH4-FB1 eventually yielded three chromatographic peaks in HPLC. However, MS revealed that the metabolites of the three peaks all had the same mass as the initial single-peak DH4-FB1. The results suggest that DH4-FB1 can undergo spontaneous isomerization, probably including both cis-trans stereoisomerization and 3'- to 2'-ene regioisomerization. In addition, when FUM7 was expressed in Escherichia coli and the resulting enzyme, Fum7p, was incubated with DH4-FB, no fumonisin with typical tricarballylic esters was formed. Instead, new fumonisin analogs that probably contained isocitrate and/or oxalosuccinate esters were formed, which reveals new insight into fumonisin biosynthesis. Together, the data provided both genetic and biochemical evidence for the mechanism of tricarballylic ester formation in fumonisin biosynthesis. PMID:24587959

  11. Tricarballylic ester formation during biosynthesis of fumonisin mycotoxins in Fusarium verticillioides

    PubMed Central

    Lia, Yaoyao; Lou, Lili; Cerny, Ronald L.; Butchko, Robert A.E.; Proctor, Robert H.; Shen, Yuemao; Du, Liangcheng

    2014-01-01

    Fumonisins are agriculturally important mycotoxins produced by the maize pathogen Fusarium verticillioides. The chemical structure of fumonisins contains two tricarballylic esters, which are rare structural moieties and important for toxicity. The mechanism for the tricarballylic ester formation is not well understood. FUM7 gene of F. verticillioides was predicted to encode a dehydrogenase/reductase, and when it was deleted, the mutant produced tetradehydro fumonisins (DH4–FB). MS and NMR analysis of DH4–FB1 indicated that the esters consist of aconitate with a 3′-alkene function, rather than a 2′-alkene function. Interestingly, the purified DH4–FB1 eventually yielded three chromatographic peaks in HPLC. However, MS revealed that the metabolites of the three peaks all had the same mass as the initial single-peak DH4–FB1. The results suggest that DH4–FB1 can undergo spontaneous isomerization, probably including both cis–trans stereoisomerization and 3′- to 2′-ene regioisomerization. In addition, when FUM7 was expressed in Escherichia coli and the resulting enzyme, Fum7p, was incubated with DH4–FB, no fumonisin with typical tricarballylic esters was formed. Instead, new fumonisin analogs that probably contained isocitrate and/or oxalosuccinate esters were formed, which reveals new insight into fumonisin biosynthesis. Together, the data provided both genetic and biochemical evidence for the mechanism of tricarballylic ester formation in fumonisin biosynthesis. PMID:24587959

  12. Determination of 3-Monochloropropane-1,2-diol and 2-Monochloropropane-1,3-diol (MCPD) Esters and Glycidyl Esters by Microwave Extraction in Different Foodstuffs.

    PubMed

    Marc, Corinne; Drouard-Pascarel, Valérie; Rétho, Cécile; Janvion, Patrice; Saltron, Frédéric

    2016-06-01

    This paper describes a method for the determination of 3-monochloropropane-1,2-diol and 2-monochloropropane-1,3-diol (MCPD) esters and glycidyl esters in various foodstuffs, which are isolated using microwave extraction. The next step is based on alkaline-catalyzed ester cleavage. The released glycidol is transformed into monobromopropanediol (MBPD). All compounds are derivatized in free diols (MCPD and MBPD) with phenylboronic acid and analyzed by gas chromatography-mass spectrometry (GC-MS). The method was validated for oils with a limit of quantitation (LOQ) of 0.1 mg/kg, for chips and crisps with a LOQ of 0.02 mg/kg, and for infant formula with a LOQ of 0.0025 mg/L. Recoveries of each sample were controlled by standard addition on extracts before derivatization. Quantitation was performed by the addition of isotopically labeled glycidyl and 3-monochloropropane-1,2-diol (3-MCPD) esters. PMID:27133957

  13. Cyclization of peptoids by formation of boronate esters

    PubMed Central

    Chirayil, Sara; Luebke, Kevin J.

    2011-01-01

    Introduction of conformational constraints into peptoids (N-substituted oligoglycines) will enable new applications in molecular recognition and self-assembly. Peptoids that contain both a phenylboronic acid side chain and a vicinal diol cyclize by intramolecular condensation to form boronate esters. A fluorescent indicator of free boronic acid was used to assay esterification. A galactose moiety 2 to 5 monomer units away from a boronic acid side chain in a peptoid reacts with the boronic acid in competition with the indicator. The intramolecular reaction predominates in each case, with 80–90% of the peptoid cyclized. When the diol is a simple 2,3-dihydroxypropyl group, esterification is less favored but still appreciable. PMID:22611292

  14. Determination of enthalpy of formation of methyl and ethyl esters of fatty acids.

    PubMed

    Lapuerta, Magín; Rodríguez-Fernández, José; Oliva, Fermín

    2010-02-01

    Biofuels composed by fatty acid methyl esters are widely used as partly substituting fuels for diesel fossil fuels. Additionally, it is expected that the diesel biofuel norms will be extended to ethyl esters produced from bioethanol in the upcoming years. A precise knowledge of the standard enthalpy of formation is necessary for the calculation of some parameters useful for the analysis of the combustion process and emissions of a diesel engine operating with different fuels, such as the heating value, the adiabatic flame temperature or the kinetic mechanisms. However, experimental data for this property are scarce, and only available for short-chain, saturated methyl esters. In this work, four estimation methods for the calculation of the enthalpy of formation are examined and compared. Three of them are simple methods based on groups or bonds contribution, and another one is a computational method (with Gaussian 03 software). After presenting the implementation rules for each of them, conclusions are stated based on the results attained. Gaussian and Benson-Groups methods seem to be more accurate in predicting the actual values of the enthalpy of formation, both methods considering the separation between double bonds and the edge effects in the molecule. However, only the Gaussian method considers the effect of the position of the double bond in the molecule for all the unsaturated esters. PMID:19917272

  15. Emission of sunscreen salicylic esters from desert vegetation and their contribution to aerosol formation

    NASA Astrophysics Data System (ADS)

    Matsunaga, S. N.; Guenther, A. B.; Potosnak, M. J.; Apel, E. C.

    2008-07-01

    Biogenic volatile organic compounds (BVOC) produced by plants are known to have an important role in atmospheric chemistry. However, our knowledge of the range of BVOCs produced by different plant processes is still expanding, and there remain poorly understood categories of BVOCs. In this study, emissions of a novel class of BVOC emissions were investigated in a desert region. Our study considered 8 species of common desert plants: blackbrush (Coleogyne ramosissima), desert willow (Chilopsis linearis), mesquite (Prosopis glandulosa), mondel pine (Pinus eldarica), pinyon pine (Pinus monophylla), cottonwood (Populus deltoides), saguaro cactus (Carnegiea gigantea) and yucca (Yucca baccata). The measurements focused on BVOCs with relatively high molecular weight (>C15) and/or an oxygenated functional group. Significantly high emission rates of two salicylic esters were found for blackbrush, desert willow and mesquite with emission rates of 1.4, 2.1 and 0.46 μgC dwg-1 h-1, respectively. The salicylic esters were identified as 2-ethylhexenyl salicylate (2-EHS) and 3,3,5-trimethylcyclohexenyl salicylate (homosalate) and are known as effective ultraviolet (UV) absorbers. We propose that the plants derive a protective benefit against UV radiation from the salicylic esters and that the emission process is driven by the physical evaporation of the salicylic esters due to the high ambient temperatures. In addition, the salicylic esters are predicted to be an effective precursor of secondary organic aerosol (SOA) because of their low vapor pressure due to a high number of carbon atoms (15 or 16) and the presence of three oxygen atoms. We estimated the contribution of the sunscreen esters themselves and their oxidation products on the SOA formation for the Las Vegas region using a BVOC emission model. The contribution was estimated to reach 90% of the biogenic SOA in the landscapes dominated by desert willow and mesquite and 25% in Las Vegas area.

  16. Emission of sunscreen salicylic esters from desert vegetation and their contribution to aerosol formation

    NASA Astrophysics Data System (ADS)

    Matsunaga, S. N.; Guenther, A. B.; Potosnak, M. J.; Apel, E. C.

    2008-12-01

    Biogenic volatile organic compounds (BVOC) produced by plants are known to have an important role in atmospheric chemistry. However, our knowledge of the range of BVOCs produced by different plant processes is still expanding, and there remain poorly understood categories of BVOCs. In this study, emissions of a novel class of BVOC emissions were investigated in a desert region. Our study considered 8 species of common desert plants: blackbrush (Coleogyne ramosissima), desert willow (Chilopsis linearis), mesquite (Prosopis glandulosa), mondel pine (Pinus eldarica), pinyon pine (Pinus monophylla), cottonwood (Populus deltoides), saguaro cactus (Carnegiea gigantea) and yucca (Yucca baccata). The measurements focused on BVOCs with relatively high molecular weight (>C15) and/or an oxygenated functional group. Significantly high emission rates of two salicylic esters were found for blackbrush, desert willow and mesquite with emission rates of 3.1, 1.0 and 4.8μgC dwg-1 h-1, respectively (dwg; dry weight of the leaves in gram). The salicylic esters were identified as 2-ethylhexenyl salicylate (2-EHS) and 3,3,5-trimethylcyclohexenyl salicylate (homosalate) and are known as effective ultraviolet (UV) absorbers. We propose that the plants derive a protective benefit against UV radiation from the salicylic esters and that the emission process is driven by the physical evaporation of the salicylic esters due to the high ambient temperatures. In addition, the salicylic esters are predicted to be an effective precursor of secondary organic aerosol (SOA) because they probably produce oxidation products that can condense onto the aerosol phase. We estimated the contribution of the sunscreen esters themselves and their oxidation products on the SOA formation for the Las Vegas area using a BVOC emission model. The contribution was estimated to reach 50% of the biogenic terpenoid emission in the landscapes dominated by desert willow and mesquite and 13% in the Las Vegas area. The

  17. Formate esters of 1,2-ethanediol - Major decomposition products of p-dioxane during storage

    NASA Technical Reports Server (NTRS)

    Jewett, D.; Lawless, J. G.

    1980-01-01

    Research done on detecting the contaminants of p-dioxane that cause a positive response for highly reactive acyl groups is discussed. Attention is given to the fact that the positive hydroxamate response might indicate an unsuspected hazard. It is found that all acyl groups transferred are formyl groups, and the mono- and diformates of 1,2-ethanediol are identified as major sources of this activity. It is also found that the formate esters are formed by way of peroxide intermediates. Concentrations of the formate ester group as high as 1.8 M are found in partially consumed bottles of dioxane but not in other common ethers stored under similar conditions. Attention is called to the possibility that the exposure to the glycol formates is probably much wider than expected. It is noted that by purging containers of dioxane with nitrogen each time they are opened and storing them in the cold away from light can prevent both the economic loss and possible health hazard caused by contamination with peroxide and formate ester.

  18. Gold-catalyzed efficient formation of alkenyl enol esters/carbonates from trimethylsilylmethyl-substituted propargyl esters/carbonates.

    PubMed

    Wang, Shaozhong; Zhang, Liming

    2006-09-28

    A gold-catalyzed efficient method for the preparation of alkenyl enol esters/carbonates is developed. Besides the mild reaction conditions and high catalytic efficiency, the excellent E-selectivity of the nonenolic double bond is remarkable. PMID:16986956

  19. Consideration of Sludge Formation in HFC-134a / Polyol Ester oil Refrigeration System

    NASA Astrophysics Data System (ADS)

    Yamamoto, Tsutomu; Yamamoto, Tethuya; Simizu, Yasuhiko; Nakayama, Yoshinori; Takizawa, Kikuo

    A refrigeration test employing HFC-134a and polyol ester oil was carried out in order to make clear the causes of the sludge formation in the capillary tube. Compressors used were two types: a hermetic reciprocating compressor and a rotary compressor. Installed dryer contained desiccant of the compound zeolite type. The results showed that the amount of capillary sludge increased as the compressor temperature rose. The capillary sludge was determined to consist of desiccant and metal dust for the reciprocating compressor, and of tar-like substance for the rotary compressor. Thermal stability test which was used to check the degree of deterioration of the ester oil, suggested that the presence of desiccant and high compressor temperature might produce tar-like substance by the break down and polymerization of the ester oil. In addition, it was confirmed that factors affecting the sludge formation were the dirtiness of the refrigeration circuit for the reciprocating compressor, and the presence of desiccant, for the rotary compressor.

  20. Effect of chemical structure and network formation on physical properties of di(cyanate ester) thermosets.

    PubMed

    Reams, Josiah T; Guenthner, Andrew J; Lamison, Kevin R; Vij, Vandana; Lubin, Lisa M; Mabry, Joseph M

    2012-02-01

    Key physical properties of three dicyanate ester monomers, bisphenol A dicyanate (BADCy), bisphenol E dicyanate (LECy), and the dicyanate of a silicon-containing analogue of bisphenol A (SiMCy) were investigated as a function of cyanurate conversion at conversions ranging from approximately 70% to greater than 90% in order to assess the range of applicability of both traditional and more unusual structure-property-process relationships known for cyanate ester resins. A more complete understanding of these relationships is essential for the continued development of cyanate ester resins and their composites for a wide variety of aerospace applications. The degree of cure in each system was determined by differential scanning calorimetry (DSC). The degree of conversion achieved at a given temperature was dependent on the structure of the repeat unit, with SiMCy displaying the highest relative ease of cure. The density at room temperature was found to decrease monotonically with increasing conversion for all monomer types studied. In contrast, the water uptake decreased with increasing cure for all three materials over most or all of the conversion range studied, but leveled off or began to increase with increasing conversion at conversions of approximately 90%. The T(g) decreased after exposure to hot water in resins with greater than 85% conversion, but unexpectedly increased in samples with lower conversions. An investigation of the effect of hot water exposure on network chemistry via infrared spectroscopy indicated that carbamate formation varied with both monomer chemistry and extent of cure, but was greatest for the BADCy polycyanurates. On the other hand, the unreacted cyanate ester band tended to disappear uniformly, suggesting that reactions other than carbamate formation (such as cyclotrimerization) may also take place during exposure to hot water, possibly giving rise to the observed unusual increases in T(g) upon exposure. PMID:22311550

  1. A free-standing condensation enzyme catalyzing ester bond formation in C-1027 biosynthesis.

    PubMed

    Lin, Shuangjun; Van Lanen, Steven G; Shen, Ben

    2009-03-17

    Nonribosomal peptide synthetases (NRPSs) catalyze the biosynthesis of many biologically active peptides and typically are modular, with each extension module minimally consisting of a condensation, an adenylation, and a peptidyl carrier protein domain responsible for incorporation of an amino acid into the growing peptide chain. C-1027 is a chromoprotein antitumor antibiotic whose enediyne chromophore consists of an enediyne core, a deoxy aminosugar, a benzoxazolinate, and a beta-amino acid moiety. Bioinformatics analysis suggested that the activation and incorporation of the beta-amino acid moiety into C-1027 follows an NRPS mechanism whereby biosynthetic intermediates are tethered to the peptidyl carrier protein SgcC2. Here, we report the biochemical characterization of SgcC5, an NRPS condensation enzyme that catalyzes ester bond formation between the SgcC2-tethered (S)-3-chloro-5-hydroxy-beta-tyrosine and (R)-1-phenyl-1,2-ethanediol, a mimic of the enediyne core. SgcC5 uses (S)-3-chloro-5-hydroxy-beta-tyrosyl-SgcC2 as the donor substrate and exhibits regiospecificity for the C-2 hydroxyl group of the enediyne core mimic as the acceptor substrate. Remarkably, SgcC5 is also capable of catalyzing amide bond formation, albeit with significantly reduced efficiency, between (S)-3-chloro-5-hydroxy-beta-tyrosyl-(S)-SgcC2 and (R)-2-amino-1-phenyl-1-ethanol, an alternative enediyne core mimic bearing an amine at its C-2 position. Thus, SgcC5 is capable of catalyzing both ester and amide bond formation, providing an evolutionary link between amide- and ester-forming condensation enzymes. PMID:19246381

  2. Direct determination of fatty acid esters of 3-chloro-1, 2-propanediol in edible vegetable oils by isotope dilution - ultra high performance liquid chromatography - triple quadrupole mass spectrometry.

    PubMed

    Li, Heli; Chen, Dawei; Miao, Hong; Zhao, Yunfeng; Shen, Jianzhong; Wu, Yongning

    2015-09-01

    A selective and sensitive ultra-high performance liquid chromatography - triple quadrupole mass spectrometry (UHPLC-MS/MS) method coupled with matrix solid phase dispersion (MSPD) extraction was developed for the direct determination of fatty acid esters of 3-chloro-1,2-propanediol (3-MCPD esters) in edible vegetable oils. The method integrated the isotope dilution technique, MSPD extraction and UHPLC - MS/MS analysis with multi-reaction monitoring mode (MRM). Matrix-matched calibration curves showed good linearity within the range of 0.01-10mgL(-1) with the correlation coefficient not less than 0.999. Limits of detection (LODs) and limit of quantification (LOQs) of the 3-MCPD esters fell into the range of 0.0001-0.02mgkg(-1) and 0.0004-0.05mgkg(-1), respectively. The recoveries for the spiked extra virgin olive oils ranged from 94.4% to 108.3%, with the relative standard deviations (RSD) ranging from 0.6% to 10.5%. The method was applied for the oil sample (T2642) of the official Food Analysis Performance Assessment Scheme (FAPAS) in 2014 and other real samples from supermarket, and the results showed that the present method was comparative to the gas chromatography-mass spectrometry (GC-MS) method based on the improved German Society for Fat Science (DGF) standard method C-III 18 (09) except for palm oil. PMID:26239698

  3. Condensation Reactions and Formation of Amides, Esters, and Nitriles Under Hydrothermal Conditions

    NASA Astrophysics Data System (ADS)

    Rushdi, Ahmed I.; Simoneit, Bernd R. T.

    2004-06-01

    Hydrothermal pyrolysis experiments were performed to assess condensation (dehydration) reactions to amide, ester, and nitrile functionalities from lipid precursors. Beside product formation, organic compound alteration and stability were also evaluated. Mixtures of nonadecanoic acid, hexadecanedioic acid, or hexadecanamide with water, ammonium bicarbonate, and oxalic acid were heated at 300°C for 72 h. In addition, mixtures of ammonium bicarbonate and oxalic acid solutions were used to test the abiotic formation of organic nitrogen compounds at the same temperature. The resulting products were condensation compounds such as amides, nitriles, and minor quantities of N-methylalkyl amides, alkanols, and esters. Mixtures of alkyl amide in water or oxalic acid yielded mainly hydrolysis and dehydration products, and with ammonium bicarbonate and oxalic acid the yield of condensation products was enhanced. The synthesis experiments with oxalic acid and ammonium bicarbonate solutions yielded homologous series of alkyl amides, alkyl amines, alkanes, and alkanoic acids, all with no carbon number predominances. These organic nitrogen compounds are stable and survive under the elevated temperatures of hydrothermal fluids.

  4. Translation inhibitors induce formation of cholesterol ester-rich lipid droplets.

    PubMed

    Suzuki, Michitaka; Ohsaki, Yuki; Tatematsu, Tsuyako; Shinohara, Yuki; Maeda, Takashi; Cheng, Jinglei; Fujimoto, Toyoshi

    2012-01-01

    Lipid droplets (LDs) in non-adipocytes contain triglycerides (TG) and cholesterol esters (CE) in variable ratios. TG-rich LDs are generated when unsaturated fatty acids are administered, but the conditions that induce CE-rich LD formation are less well characterized. In the present study, we found that protein translation inhibitors such as cycloheximide (CHX) induced generation of CE-rich LDs and that TIP47 (perilipin 3) was recruited to the LDs, although the expression of this protein was reduced drastically. Electron microscopy revealed that LDs formed in CHX-treated cells possess a distinct electron-dense rim that is not found in TG-rich LDs, whose formation is induced by oleic acid. CHX treatment caused upregulation of mTORC1, but the CHX-induced increase in CE-rich LDs occurred even when rapamycin or Torin1 was given along with CHX. Moreover, the increase in CE was seen in both wild-type and autophagy-deficient Atg5-null mouse embryonic fibroblasts, indicating that mTORC1 activation and suppression of autophagy are not necessary to induce the observed phenomenon. The results showed that translation inhibitors cause a significant change in the lipid ester composition of LDs by a mechanism independent of mTORC1 signaling and autophagy. PMID:22879956

  5. Effect of caffeic acid phenethyl ester on bone formation in the expanded inter-premaxillary suture

    PubMed Central

    Kazancioglu, Hakki Oguz; Aksakalli, Sertac; Ezirganli, Seref; Birlik, Muhammet; Esrefoglu, Mukaddes; Acar, Ahmet Hüseyin

    2015-01-01

    Background Narrow maxilla is a common problem in orthodontics and dentofacial orthopedics. To solve this problem, a procedure called rapid maxillary expansion (RME) has been used. However, relapse tendency is a major problem of RME. Although relapse tendency is not clearly understood, various treatment procedures and new applications have been investigated. The present study aimed to investigate the possible effectiveness of caffeic acid phenethyl ester (CAPE) on new bone formation in rat midpalatal suture after RME. Materials and methods Twenty male Sprague Dawley rats were used in this study. The animals were randomly divided into two groups as control and CAPE group. In the CAPE group, CAPE was administered systemically via intraperitoneal injection. RME procedure was performed on all animals. For this purpose, the springs were placed on the maxillary incisors of rats and activated for 5 days. After then, the springs were removed and replaced with short lengths of rectangular retaining wire for consolidation period of 15 days. At the end of the study, histomorphometric analysis was carried out to assess new bone formation. Results New bone formation was significantly greater in the CAPE group than the control group (P<0.05). CAPE enhances new bone formation in midpalatal suture after RME. Conclusion These results show that CAPE may decrease the time needed for retention. PMID:26730181

  6. Minimally oxidized LDL inhibits macrophage selective cholesteryl ester uptake and native LDL-induced foam cell formation[S

    PubMed Central

    Meyer, Jason M.; Ji, Ailing; Cai, Lei; van der Westhuyzen, Deneys R.

    2014-01-01

    Scavenger receptor-mediated uptake of oxidized LDL (oxLDL) is thought to be the major mechanism of foam cell generation in atherosclerotic lesions. Recent data has indicated that native LDL is also capable of contributing to foam cell formation via low-affinity receptor-independent LDL particle pinocytosis and selective cholesteryl ester (CE) uptake. In the current investigation, Cu2+-induced LDL oxidation was found to inhibit macrophage selective CE uptake. Impairment of selective CE uptake was significant with LDL oxidized for as little as 30 min and correlated with oxidative fragmentation of apoB. In contrast, LDL aggregation, LDL CE oxidation, and the enhancement of scavenger receptor-mediated LDL particle uptake required at least 3 h of oxidation. Selective CE uptake did not require expression of the LDL receptor (LDL-R) and was inhibited similarly by LDL oxidation in LDL-R−/− versus WT macrophages. Inhibition of selective uptake was also observed when cells were pretreated or cotreated with minimally oxidized LDL, indicating a direct inhibitory effect of this oxLDL on macrophages. Consistent with the effect on LDL CE uptake, minimal LDL oxidation almost completely prevented LDL-induced foam cell formation. These data demonstrate a novel inhibitory effect of mildly oxidized LDL that may reduce foam cell formation in atherosclerosis. PMID:24891335

  7. Fate of Tetrabromobisphenol A (TBBPA) and Formation of Ester- and Ether-Linked Bound Residues in an Oxic Sandy Soil.

    PubMed

    Li, Fangjie; Wang, Jiajia; Jiang, Bingqi; Yang, Xue; Nastold, Peter; Kolvenbach, Boris; Wang, Lianhong; Ma, Yini; Corvini, Philippe François-Xavier; Ji, Rong

    2015-11-01

    Bound-residue formation is a major dissipation process of most organic xenobiotics in soil. However, both the formation and nature of bound residues of tetrabromobisphenol A (TBBPA) in soil are unclear. Using a 14C-tracer, we studied the fate of TBBPA in an oxic soil during 143 days of incubation. TBBPA dissipated with a half-life of 14.7 days; at the end of incubation, 19.6% mineralized and 66.5% formed bound residues. Eight extractable metabolites were detected, including TBBPA methyl ethers, single-ring bromophenols, and their methyl ethers. Bound residues (mostly bound to humin) rapidly formed during the first 35 days. The amount of those humin-bound residues then quickly decreased, whereas total bound residues decreased slowly. By contrast, residues bound to humic acids and fulvic acids increased continuously until a plateau was reached. Ester- and ether-linked residues accounted for 9.6-27.0% of total bound residues during the incubation, with ester linkages being predominant. Residues bound via ester linkages consisted of TBBPA, TBBPA monomethyl ether, and an unknown polar compound. Our results indicated that bound-residue formation is the major pathway of TBBPA dissipation in oxic soil and provide first insights into the chemical structure of the reversibly ester-linked bound residues of TBBPA and its metabolites. PMID:26444952

  8. Insights into the formation mechanism of chloropropanol fatty acid esters under laboratory-scale deodorization conditions.

    PubMed

    Hori, Katsuhito; Hori-Koriyama, Natsuko; Tsumura, Kazunobu; Fukusaki, Eiichiro; Bamba, Takeshi

    2016-08-01

    Chloropropanol fatty acid esters (CPFAEs) are well-known contaminants in refined oils and fats, and several research groups have studied their formation. However, the results obtained in these studies were not satisfactory because the CPFAEs were not analyzed comprehensively. Thus, in the present study, a comprehensive analysis was performed to obtain new details about CPFAE formation. Each lipid (monopalmitin, dipalmitin, tripalmitin, monoolein, diolein, triolein, and crude palm oil) was heated at 250°C for 90 min, and the CPFAEs were analyzed using supercritical fluid chromatography/tandem mass spectrometry. It was found that CP fatty acid monoesters were formed from monoacylglycerols and diacylglycerols after heating in the presence of a chlorine compound. In addition, CP fatty acid diesters were formed from diacylglycerols and triacylglycerols under the same conditions. In the case of crude palm oil, only CP fatty acid diesters were formed. Therefore, these results indicated that CPFAEs in refined palm oil were formed mainly from triacylglycerols. PMID:26822095

  9. Improved δ-valerolactam templates for the assembly of Aβ-miniamyloids by boronic ester formation.

    PubMed

    Wuttke, André; Fischer, Sebastian Nils; Nebel, Annika; Marsch, Michael; Geyer, Armin

    2016-06-14

    The 6,7,8,8a-cis (all-cis) substituted δ-valerolactams of type 10, 11 and 12 are high-affinity diols for boronic ester formation, superior to the corresponding 6,7-trans analogues 1, 3 and 4. X-ray and NMR structure analysis have identified the differences of the six-membered ring conformations which cause the improved esterification properties of the all-cis stereoisomers. The homooligomeric all-cisδ-valerolactams 46-48 are used as polyol templates for the self-assembly of peptidic oligomers 49-52 by dynamic covalent chemistry. The templates have a diol spacing of approximately 5 Å, suitable for the assembly of branched peptides from the quantitative reaction between the peptide of interest, 2-formylphenylboronic acid and the respective template. According to this strategy, the tetrameric Aβ-miniamyloid 52 formed spontaneously from nine individual molecules in a three-component system. A detailed NMR analysis based on the complete sequential assignment of the trimeric Aβ(32-40)-miniamyloid 51 identified its three-dimensional structure in solution. PMID:27104617

  10. Electrolysis of trichloromethylated organic compounds under aerobic conditions catalyzed by the B12 model complex for ester and amide formation.

    PubMed

    Shimakoshi, Hisashi; Luo, Zhongli; Inaba, Takuya; Hisaeda, Yoshio

    2016-06-21

    The electrolysis of benzotrichloride at -0.9 V vs. Ag/AgCl in the presence of the B12 model complex, heptamethyl cobyrinate perchlorate, in ethanol under aerobic conditions using an undivided cell equipped with a platinum mesh cathode and a zinc plate anode produced ethylbenzoate in 56% yield with 92% selectivity. The corresponding esters were obtained when the electrolysis was carried out in various alcohols such as methanol, n-propanol, and i-propanol. Benzoyl chloride was detected by GC-MS during the electrolysis as an intermediate for the ester formation. When the electrolysis was carried out under anaerobic conditions, partially dechlorinated products, 1,1,2,2-tetrachloro-1,2-diphenylethane and 1,2-dichlorostilibenes (E and Z forms), were obtained instead of an ester. ESR spin-trapping experiments using 5,5,-dimethylpyrroline N-oxide (DMPO) revealed that the corresponding oxygen-centered radical and carbon-centered radical were steadily generated during the electrolyses under aerobic and anaerobic conditions, respectively. Applications of the aerobic electrolysis to various organic halides, such as substituted benzotrichlorides, are described. Furthermore, the formation of amides with moderate yields by the aerobic electrolysis of benzotrichloride catalyzed by the B12 model complex in the presence of amines in acetonitrile is reported. PMID:27071703

  11. Novel decomposition products of chlorophyll- a in continental shelf (Louisiana shelf) sediments: formation and transformation of carotenol chlorin esters

    NASA Astrophysics Data System (ADS)

    Chen, Nianhong; Bianchi, Thomas S.; Bland, John M.

    2003-06-01

    In April 2000, we collected box cores from five stations along a cross-shelf transect on the Louisiana (LA) continental shelf. Novel esters of carotenols and chlorins (carotenoid chlorin esters, CCEs), which are highly specific grazing markers, were identified in surface and deep sediments (>10 cm) from the LA shelf. Chlorophyll- a inventory indicated that CCEs are one of the major decay products of chlorophyll- a in shelf sediments. Abundances of total CCEs (9-18%) in surface sediments along the cross-shelf transect were comparable to the abundance of pheophytin- a, pyropheophytin- a, and total steryl chlorin esters (SCEs). Prior work has identified four CCEs which have dehydrated fucoxanthin/fucoxanthinol as a substitute alcohol of phytol. We report on four newly identified CCEs associated with nondehydrated fuxocanthin/fucoxanthinol esterified to (pyro)pheophorbide- a. These nondehydrated CCEs were generally present in lower concentrations than their dehydrated counterparts, but were detectable by atmospheric pressure chemical ionization (APCI) mass spectrometry coupled with high-performance liquid chromatography (HPLC). We attributed differences between this study and previous work to the time allowed for predepositional decay and grazing processes to occur. The rapid sedimentation of CCEs in the shallow water column (ca. 10 m) on the LA shelf allowed for effective burial of all CCEs compared to the deeper water column regions sampled by previous work. This speculation is supported by the fact that the concentrations of CCEs with nondehydrated fucoxanthin/fucoxanthinol were extremely low in sediments from the site on the outer LA shelf with a deeper (253 m) water column. We also tentatively identified an additional CCE and its isomer as fucoxanthinol didehydrate pyropheophorbide- a ester. We suggest that the formation and transformation of CCEs are primarily controlled by the following three biologically mediated reactions: demethoxycarbonylation, dehydration

  12. Nasal retention of budesonide and fluticasone in man: Formation of airway mucosal budesonide-esters in vivo

    PubMed Central

    Petersen, Hannes; Kullberg, Annika; Edsbäcker, Staffan; Greiff, Lennart

    2001-01-01

    biopsies, respectively. Conclusions The present study demonstrates the formation of budesonide-esters in the human nasal mucosa in vivo, and that budesonide is retained in the nasal mucosa to a greater extent than fluticasone propionate. It is suggested that the formation of budesonide-esters and their subsequent release of budesonide contributes to an extended retention of budesonide in the airway mucosa. PMID:11259988

  13. Expression Levels of the Yeast Alcohol Acetyltransferase Genes ATF1, Lg-ATF1, and ATF2 Control the Formation of a Broad Range of Volatile Esters

    PubMed Central

    Verstrepen, Kevin J.; Van Laere, Stijn D. M.; Vanderhaegen, Bart M. P.; Derdelinckx, Guy; Dufour, Jean-Pierre; Pretorius, Isak S.; Winderickx, Joris; Thevelein, Johan M.; Delvaux, Freddy R.

    2003-01-01

    Volatile aroma-active esters are responsible for the fruity character of fermented alcoholic beverages such as beer and wine. Esters are produced by fermenting yeast cells in an enzyme-catalyzed intracellular reaction. In order to investigate and compare the roles of the known Saccharomyces cerevisiae alcohol acetyltransferases, Atf1p, Atf2p and Lg-Atf1p, in volatile ester production, the respective genes were either deleted or overexpressed in a laboratory strain and a commercial brewing strain. Subsequently, the ester formation of the transformants was monitored by headspace gas chromatography and gas chromatography combined with mass spectroscopy (GC-MS). Analysis of the fermentation products confirmed that the expression levels of ATF1 and ATF2 greatly affect the production of ethyl acetate and isoamyl acetate. GC-MS analysis revealed that Atf1p and Atf2p are also responsible for the formation of a broad range of less volatile esters, such as propyl acetate, isobutyl acetate, pentyl acetate, hexyl acetate, heptyl acetate, octyl acetate, and phenyl ethyl acetate. With respect to the esters analyzed in this study, Atf2p seemed to play only a minor role compared to Atf1p. The atf1Δ atf2Δ double deletion strain did not form any isoamyl acetate, showing that together, Atf1p and Atf2p are responsible for the total cellular isoamyl alcohol acetyltransferase activity. However, the double deletion strain still produced considerable amounts of certain other esters, such as ethyl acetate (50% of the wild-type strain), propyl acetate (50%), and isobutyl acetate (40%), which provides evidence for the existence of additional, as-yet-unknown ester synthases in the yeast proteome. Interestingly, overexpression of different alleles of ATF1 and ATF2 led to different ester production rates, indicating that differences in the aroma profiles of yeast strains may be partially due to mutations in their ATF genes. PMID:12957907

  14. Conversion of biomass-derived levulinate and formate esters into γ-valerolactone over supported gold catalysts.

    PubMed

    Du, Xian-Long; Bi, Qing-Yuan; Liu, Yong-Mei; Cao, Yong; Fan, Kang-Nian

    2011-12-16

    The utilization of biomass has recently attracted tremendous attention as a potential alternative to petroleum for the production of liquid fuels and chemicals. We report an efficient alcohol-mediated reactive extraction strategy by which a hydrophobic mixture of butyl levulinate and formate esters, derived from cellulosic biomass, can be converted to valuable γ-valerolactone (GVL) by a simple supported gold catalyst system without need of an external hydrogen source. The essential role of the supported gold is to facilitate the rapid and selective decomposition of butyl formate to produce a hydrogen stream, which enables the highly effective reduction of butyl levulinate into GVL. This protocol simplifies the recovery and recycling of sulfuric acid, which is used for cellulose deconstruction. PMID:22105964

  15. Ester-Mediated Amide Bond Formation Driven by Wet-Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth.

    PubMed

    Forsythe, Jay G; Yu, Sheng-Sheng; Mamajanov, Irena; Grover, Martha A; Krishnamurthy, Ramanarayanan; Fernández, Facundo M; Hud, Nicholas V

    2015-08-17

    Although it is generally accepted that amino acids were present on the prebiotic Earth, the mechanism by which α-amino acids were condensed into polypeptides before the emergence of enzymes remains unsolved. Here, we demonstrate a prebiotically plausible mechanism for peptide (amide) bond formation that is enabled by α-hydroxy acids, which were likely present along with amino acids on the early Earth. Together, α-hydroxy acids and α-amino acids form depsipeptides-oligomers with a combination of ester and amide linkages-in model prebiotic reactions that are driven by wet-cool/dry-hot cycles. Through a combination of ester-amide bond exchange and ester bond hydrolysis, depsipeptides are enriched with amino acids over time. These results support a long-standing hypothesis that peptides might have arisen from ester-based precursors. PMID:26201989

  16. Stereoselective formation of a 2 prime (3 prime)- aminoacyl ester of a nucleotide

    NASA Technical Reports Server (NTRS)

    Weber, A. L.

    1986-01-01

    Reaction of DL-series and adenosine-5-phosphorimidazolide in the presence of adenosine-5'-(0-methylphosphate) and imidazole resulted in the stereoselective synthesis of the aminoacyl nucleotide ester, 2'(3')-0-seryl-adenosine-5'-(0-methylphosphate). The enantiomeric excess of D-serine incorporated into 2'(3')-0-seryl-adenosine-5'-(0-methylphosphate) was about 9%. Adenylyl-(5->N)-serine and an unknown product also incorporated an excess of D-serine, however, seryl-serine showed an excess of L-serine. The relationship of these results to the origin of the biological pairing of L-amino acids and nucleotides containing D-ribose is discussed.

  17. Facile Formation of β-Hydroxyboronate Esters by a Cu-Catalyzed Diboration/Matteson Homologation Sequence

    PubMed Central

    2015-01-01

    The copper-catalyzed diboration of aldehydes was used in conjunction with the Matteson homologation, providing the efficient synthesis of β-hydroxyboronate esters. The oxygen-bound boronate ester was found to play a key role in mediating the homologation reaction, which was compared to the α-hydroxyboronate ester (isolated hydrolysis product). The synthetic utility of the diboration/homologation sequence was demonstrated through the oxidation of one product to provide a 1,2-diol. PMID:25412356

  18. Palladium-catalyzed C–N and C–O bond formation of N-substituted 4-bromo-7-azaindoles with amides, amines, amino acid esters and phenols

    PubMed Central

    Surasani, Rajendra; Rao, A V Dhanunjaya; Chandrasekhar, K B

    2012-01-01

    Summary Simple and efficient procedures for palladium-catalyzed cross-coupling reactions of N-substituted 4-bromo-7-azaindole (1H-pyrrole[2,3-b]pyridine), with amides, amines, amino acid esters and phenols through C–N and C–O bond formation have been developed. The C–N cross-coupling reaction of amides, amines and amino acid esters takes place rapidly by using the combination of Xantphos, Cs2CO3, dioxane and palladium catalyst precursors Pd(OAc)2/Pd2(dba)3. The combination of Pd(OAc)2, Xantphos, K2CO3 and dioxane was found to be crucial for the C–O cross-coupling reaction. This is the first report on coupling of amides, amino acid esters and phenols with N-protected 4-bromo-7-azaindole derivatives. PMID:23209536

  19. Ester-Mediated Amide Bond Formation Driven by Wet–Dry Cycles: A Possible Path to Polypeptides on the Prebiotic Earth**

    PubMed Central

    Forsythe, Jay G; Yu, Sheng-Sheng; Mamajanov, Irena; Grover, Martha A; Krishnamurthy, Ramanarayanan; Fernández, Facundo M; Hud, Nicholas V

    2015-01-01

    Although it is generally accepted that amino acids were present on the prebiotic Earth, the mechanism by which α-amino acids were condensed into polypeptides before the emergence of enzymes remains unsolved. Here, we demonstrate a prebiotically plausible mechanism for peptide (amide) bond formation that is enabled by α-hydroxy acids, which were likely present along with amino acids on the early Earth. Together, α-hydroxy acids and α-amino acids form depsipeptides—oligomers with a combination of ester and amide linkages—in model prebiotic reactions that are driven by wet–cool/dry–hot cycles. Through a combination of ester–amide bond exchange and ester bond hydrolysis, depsipeptides are enriched with amino acids over time. These results support a long-standing hypothesis that peptides might have arisen from ester-based precursors. PMID:26201989

  20. Characterization of enzymes involved in formation of ethyl esters of long-chain fatty acids in humans.

    PubMed

    Diczfalusy, M A; Björkhem, I; Einarsson, C; Hillebrant, C G; Alexson, S E

    2001-07-01

    Elevated fatty acid ethyl ester (FAEE) concentrations have been detected in postmortem organs from alcoholics and patients acutely intoxicated by alcohol, and FAEE have been implicated as mediators of ethanol-induced organ damage. The formation of FAEE is catalyzed by acyl-coenzyme A:ethanol O-acyltransferase (AEAT) and by FAEE synthase, which utilize acyl-CoA and free fatty acids, respectively, as substrates. Because little is known about the capacity of various human tissues to synthesize and hydrolyze FAEE, we investigated formation of FAEE by AEAT and FAEE synthase in tissue homogenates from human gastric ventricular and duodenal mucosa, pancreas, liver, heart, lung, and adipose tissue, gallbladder mucosa, and in serum. Liver, duodenal mucosa, and pancreas were found to have the highest capacities to synthesize FAEE, mainly due to AEAT. FAEE hydrolyzing activity was highest in liver and pancreas, but hardly detectable in adipose tissue or heart. Because fatty acids and alcohol are absorbed by the intestinal mucosa, intestine may be a major site of FAEE synthesis, and FAEE may be delivered via the circulation to other organs and taken up by lipoprotein receptor-mediated uptake. A very low rate of FAEE hydrolysis was detected in heart and adipose tissue, which probably accounts for the previously observed accumulation of FAEE in these organs. PMID:11441128

  1. MAP kinase mediates epidermal growth factor- and phorbol ester-induced prostacyclin formation in cardiomyocytes.

    PubMed

    Braconi Quintaje, S; Rebsamen, M; Church, D J; Vallotton, M B; Lang, U

    1998-05-01

    We studied the role of protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) in epidermal growth factor (EGF)-induced prostacyclin (PGI2) production in cultured, spontaneously-beating neonatal ventricular rat cardiomyocytes. To this purpose, the effect of EGF on cardiomyocyte MAPK phosphorylation, MAPK activity and PGI2-production were investigated, and compared to those induced by the PKC activator 4 beta phorbol 12-myristate 13-acetate (PMA). Both EGF (0.1 microM) and PMA (0.1 microM) induced the rapid and reversible phosphorylation of 42 KDa-MAPK in ventricular cardiomyocytes, responses that were accompanied by transient increases in MAPK activity (190-230% of control values within 5 min), and two- to three-fold increases in PGI2 formation. The tyrosine kinase inhibitors lavendustin (1 microM) and genistein (10 microM) strongly inhibited EGF-induced MAPK activation and PGI2-formation, but had no effect on PMA-stimulated responses. Experiments with the PKC inhibitor CGP 41251 (1 microM) or with PKC-downregulated cells demonstrated that in contrast to the PMA-stimulated responses, EGF-induced MAPK activation and PGI2-production were PKC-independent processes. Investigating the role of MAPK in EGF- and in PMA-promoted PGI2-formation, we found that the MAPK-inhibitor 6-thioguanine (500 microM), as well as the MAPK-kinase-inhibitor PD98059 (50 microM) abolished both EGF- and PMA-stimulated PGI2-production in cardiomyocytes. Our results indicate that MAPK-activation is at the basis of both growth factor receptor and PKC-dependent eicosanoid-formation in ventricular cardiomyocytes, where EGF-induced prostaglandin-production takes place via a PKC-independent pathway. PMID:9618234

  2. Epidermal growth factor (EGF)-stimulated inositol phosphate formation in hepatocytes is abolished by pertussis toxin and phorbol esters

    SciTech Connect

    Johnson, R.M.; Garrison, J.C.

    1987-05-01

    The EGF-stimulated rise in intracellular Ca/sup 2 +/ (Ca/sup 2 +/)/sub i/ and Ca/sup 2 +/-dependent protein phosphorylation events in isolated hepatocytes are blocked by pertussis toxin and phorbol ester pretreatment. The present study characterized the EGF-stimulated formation of inositol 1,4,5-trisphosphate (Ins(1,4,5)P/sub 3/) and inositol 1,3,4-trisphosphate (Ins(1,3,4)P/sub 3/) in hepatocytes using HPLC methodology to separate the InsP/sub 3/ isomers. Both 66 nM EGF and 10 nM angiotensin II (ANG II) caused a rapid increase in the Ins(1,4,5)P/sub 3/ isomer although EGF-stimulated formation was smaller. At a concentration of ANG II (0.1 nM) which gave an equivalent rise in (Ca/sup 2 +/)/sub i/ as 66 nM EGF, the kinetics and magnitude of Ins(1,4,5)P/sub 3/ formation were similar. EGF or ANG II-stimulated formation of the Ins(1,3,4)P/sub 3/ isomer was more gradual and increased beyond the level of Ins(1,4,5)P/sub 3/ after 60 sec. The initial EGF and ANG II-stimulated increase in both InsP/sub 3/ isomers was not affected by removing external Ca/sup 2 +/ with a 10-fold excess of EGTA. Pretreatment of rats with pertussis toxin for 72 hrs blocked the ability of EGF to increase Ins(1,4,5)P/sub 3/ but did not affect the increase due to ANG II. Three main pretreatment of cells with 1 ..mu..g/ml phorbol 12-myristate-13-acetate (PMA) also inhibited the EGF-stimulated Ins(1,4,5)P/sub 3/ formation. PMA slightly attenuated Ins(1,4,5)P/sub 3/ formation stimulated by 0.1 nM ANG II but not enough to affect the Ca/sup 2 +/ signal. These data suggest that the signal transduction system used by EGF receptors to increase Ins (1,4,5)P/sub 3/ in hepatocytes is somehow different from that used by ANG II receptors.

  3. Studies of the acidic components of the Colorado Green River formation oil shale-Mass spectrometric identification of the methyl esters of extractable acids.

    NASA Technical Reports Server (NTRS)

    Haug, P.; Schnoes, H. K.; Burlingame, A. L.

    1971-01-01

    Study of solvent extractable acidic constituents of oil shale from the Colorado Green River Formation. Identification of individual components is based on gas chromatographic and mass spectrometric data obtained for their respective methyl esters. Normal acids, isoprenoidal acids, alpha, omega-dicarboxylic acids, mono-alpha-methyl dicarboxylic acids and methyl ketoacids were identified. In addition, the presence of monocyclic, benzoic, phenylalkanoic and naphthyl-carboxylic acids, as well as cycloaromatic acids, is demonstrated by partial identification.

  4. Oxygen-Controlled Catalysis by Vitamin B12 -TiO2 : Formation of Esters and Amides from Trichlorinated Organic Compounds by Photoirradiation.

    PubMed

    Shimakoshi, Hisashi; Hisaeda, Yoshio

    2015-12-14

    An oxygen switch in catalysis of the cobalamin derivative (B12 )-TiO2 hybrid catalyst for the dechlorination of trichlorinated organic compounds has been developed. The covalently bound B12 on the TiO2 surface transformed trichlorinated organic compounds into an ester and amide by UV light irradiation under mild conditions (in air at room temperature), while dichlorostilbenes (E and Z forms) were formed in nitrogen from benzotrichloride. A benzoyl chloride was formed as an intermediate of the ester and amide, which was detected by GC-MS. The substrate scope of the synthetic strategy is demonstrated with a range of various trichlorinated organic compounds. A photo-duet reaction utilizing the hole and conduction band electron of TiO2 in B12 -TiO2 for the amide formation was also developed. PMID:26526962

  5. Studies on the Effect of Sub-zero Temperatures on the Formation of Extremely Low Volatility Dimer Esters in Secondary Organic Aerosol from Alpha-Pinene

    NASA Astrophysics Data System (ADS)

    Kristensen, Kasper; Normann Jensen, Louise; Bilde, Merete

    2016-04-01

    The oxidation of volatile organic compounds (VOC) is considered a major source of secondary organic aerosols (SOA) in the atmosphere. Recently, extremely low volatility organic compounds, or ELVOC, formed from the oxidation of VOCs have been shown to play a crucial role in new particle formation (Ehn et al., 2014). In addition, higher molecular weight dimer esters originating from the oxidation of the biogenic VOC alpha-pinene have been observed in both laboratory-generated and ambient SOA (Kristensen et al., 2013). The low volatility of the dimer esters along with an observed rapid formation makes these high molecular weight compounds likely candidates involved in new particle formation from the oxidation of alpha-pinene. Furthermore, laboratory experiments show that the dimer esters only form in the presence of ozone, thus may be used as tracers for the ozone-initiated oxidation of alpha-pinene, and are therefore indicative of enhanced anthropogenic activities. In this work, we present the results of a series of oxidation experiments performed in the newly constructed cold-room smog chamber at Aarhus University. This unique and state-of-the-art Teflon chamber allows for atmospheric simulations of the oxidation VOCs and subsequent SOA formation at temperatures down to -16 °C. In this study, ozonolysis and photochemical oxidations of alpha-pinene are performed at temperatures ranging from +20 to -16 °C. Chemical characterization of the formed SOA is performed using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. The results show significant differences in the chemical composition related to the experiment temperature. In particularly, the concentration of the high molecular weight dimer esters showed to be highly affected by temperature. Interestingly, preliminary results show higher formation of dimer esters related to increased SOA formation rate, thus indicating that these particle-phase ELVOCs may be linked with new particle

  6. Apple Aminoacid Profile and Yeast Strains in the Formation of Fusel Alcohols and Esters in Cider Production.

    PubMed

    Eleutério Dos Santos, Caroline Mongruel; Pietrowski, Giovana de Arruda Moura; Braga, Cíntia Maia; Rossi, Márcio José; Ninow, Jorge; Machado Dos Santos, Tâmisa Pires; Wosiacki, Gilvan; Jorge, Regina Maria Matos; Nogueira, Alessandro

    2015-06-01

    The amino acid profile in dessert apple must and its effect on the synthesis of fusel alcohols and esters in cider were established by instrumental analysis. The amino acid profile was performed in nine apple musts. Two apple musts with high (>150 mg/L) and low (<75 mg/L) nitrogen content, and four enological yeast strains, were used in cider fermentation. The aspartic acid, asparagine and glutamic acid amino acids were the majority in all the apple juices, representing 57.10% to 81.95%. These three amino acids provided a high consumption (>90%) during fermentation in all the ciders. Principal component analysis (PCA) explained 81.42% of data variability and the separation of three groups for the analyzed samples was verified. The ciders manufactured with low nitrogen content showed sluggish fermentation and around 50% less content of volatile compounds (independent of the yeast strain used), which were mainly 3-methyl-1-butanol (isoamyl alcohol) and esters. However, in the presence of amino acids (asparagine, aspartic acid, glutamic acid and alanine) there was a greater differentiation between the yeasts in the production of fusel alcohols and ethyl esters. High contents of these aminoacids in dessert apple musts are essential for the production of fusel alcohols and most of esters by aromatic yeasts during cider fermentation. PMID:25920613

  7. Electrokinetic probes for single-step screening of polyol stereoisomers: the virtues of ternary boronate ester complex formation.

    PubMed

    Kaiser, Claire; Segui-Lines, Giselle; D'Amaral, Jason C; Ptolemy, Adam S; Britz-McKibbin, Philip

    2008-01-21

    Electrokinetic probes based on the differential migration of ternary boronate ester complexes permit the selective analysis of micromolar levels of UV-transparent polyol stereoisomers in urine samples via dynamic complexation-capillary electrophoresis that is applicable to single-step screening of in-born errors of sugar metabolism, such as galactosemia. PMID:18399200

  8. COLONY FORMATION ENHANCEMENT OF RAT TRACHEAL AND NASAL EPITHELIAL CELLS BY POLYACETATE, INDOLE ALKALOID, AND PHORBOL ESTER TUMOR PROMOTERS

    EPA Science Inventory

    The phorbol ester 12-0-tetradecanoylphorbol-13-acetate (TPA), teleocidin, and two polyacetate tumor promoters (aplysiatoxin and debromoaplysiatoxin) have been tested for their effect on colony forming efficiency (CFE) of rat tracheal and nasal turbinate epithelial cells. In rat t...

  9. Formation of fatty acid ethyl esters in rat liver microsomes. Evidence for a key role for acyl-CoA: ethanol O-acyltransferase.

    PubMed

    Diczfalusy, M A; Björkhem, I; Einarsson, C; Alexson, S E

    1999-01-01

    Fatty acid ethyl esters have been detected in high concentrations in organs commonly damaged by alcohol abuse and are regarded as being important non-oxidative metabolites of ethanol. The formation of fatty acid ethyl esters (FAEEs) has been ascribed to two enzymic activities, acyl-CoA : ethanol O-acyltransferase (AEAT) and FAEE synthase. In the present study we determined AEAT and FAEE synthase activities in isolated rat liver microsomes and further characterized the microsomal AEAT activity in more detail. The determined AEAT and FAEE synthase activities were found to be similar (about 1.7 nmol.min-1.mg-1). However, the AEAT activity was increased about sixfold by the addition of 250 microm bis-(4-nitrophenyl) phosphate (a serine esterase inhibitor) to the incubation whereas FAEE synthase activity was completely inhibited. p-Hydroxymercuribenzoic acid (a cysteine-reacting compound) also stimulated AEAT activity (about fourfold) but had no effect on FAEE synthase activity. The effects of the inhibitors suggest that the formation of FAEEs by AEAT was severely counteracted by enzymic hydrolysis of the substrate (acyl-CoA) and to a lesser extent the product by serine esterases. dl-Melinamide, a hypocholesterolaemic drug, was found to be a very potent inhibitor of AEAT activity with an IC50 value of about 2.5 microm. Furthermore, we compared the activities of two purified microsomal carboxylesterases, ES-4 and ES-10, and identified ES-4 as the enzyme responsible for hydrolysis of FAEEs. The two carboxyesterases were also tested for FAEE synthase activity, but neither had any detectable activity. Esterase ES-4 was found to have some AEAT activity, but it was low. When measured under optimal conditions without competing hydrolysis the capacity of AEAT is thus considerably higher than FAEE synthase and the results are consistent with an important role for AEAT in the formation of ethyl esters. As the ratio acyl-CoA/non-esterified fatty acids is high under normal

  10. Formation of Glycidyl Fatty Acid Esters Both in Real Edible Oils during Laboratory-Scale Refining and in Chemical Model during High Temperature Exposure.

    PubMed

    Cheng, Weiwei; Liu, Guoqin; Liu, Xinqi

    2016-07-27

    In the present study, the formation mechanisms of glycidyl fatty acid esters (GEs) were investigated both in real edible oils (soybean oil, camellia oil, and palm oil) during laboratory-scale preparation and refining and in chemical model (1,2-dipalmitin (DPG) and 1-monopalmitin (MPG)) during high temperature exposure (160-260 °C under nitrogen). The formation process of GEs in the chemical model was monitored using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The results showed that the roasting and pressing process could produce certain amounts of GEs that were much lower than that produced in the deodorization process. GE contents in edible oils increased continuously and significantly with increasing deodorization time below 200 °C. However, when the temperature exceeded 200 °C, GE contents sharply increased in 1-2 h followed by a gradual decrease, which could verify a simultaneous formation and degradation of GEs at high temperature. In addition, it was also found that the presence of acylglycerol (DAGs and MAGs) could significantly increase the formation yield of GEs both in real edible oils and in chemical model. Compared with DAGs, moreover, MAGs displayed a higher formation capacity but substantially lower contribution to GE formation due to their low contents in edible oils. In situ ATR-FTIR spectroscopic evidence showed that cyclic acyloxonium ion intermediate was formed during GE formation derived from DPG and MPG in chemical model heated at 200 °C. PMID:27319409

  11. Copper-catalyzed oxidative C-O bond formation of 2-acyl phenols and 1,3-dicarbonyl compounds with ethers: direct access to phenol esters and enol esters.

    PubMed

    Park, Jihye; Han, Sang Hoon; Sharma, Satyasheel; Han, Sangil; Shin, Youngmi; Mishra, Neeraj Kumar; Kwak, Jong Hwan; Lee, Cheong Hoon; Lee, Jeongmi; Kim, In Su

    2014-05-16

    A copper-catalyzed oxidative coupling of 2-carbonyl-substituted phenols and 1,3-dicarbonyl compounds with a wide range of dibenzyl or dialkyl ethers is described. This protocol provides an efficient preparation of phenol esters and enol esters in good yields with high chemoselectivity. This method represents an alternative protocol for classical esterification reactions. PMID:24762192

  12. Targeted and non-targeted boron complex formation followed by electrospray Fourier transform ion cyclotron mass spectrometry: a novel approach for identifying boron esters with natural organic matter.

    PubMed

    Gaspar, Andras; Lucio, Marianna; Harir, Mourad; Schmitt-Kopplin, Philippe

    2011-01-01

    The formation of boron esters was investigated in peat-soluble humified materials with a detailed molecular-level description of boron-organic interactions. Thousands of individually baseline separated signals were obtained from the analysis of natural organic matter of peat samples, using Fourier transform ion cyclotron resonance mass spectrometry. This technique offers unsurpassed isotope-specific mass resolution that can lead to precise molecular formula assignments by means of mathematical data analysis and visualisation techniques, such as mass defect (Kendrick) or elemental ratio (van Krevelen) plots. The analysis of potential boron binding structures within the sample of natural organic matter was described based on prior results. Herein, we describe an algorithm that can be used to effectively distinguish and filter complexes through data obtained from boron-enriched systems with highly intricate mass spectra, such as natural organic matter. PMID:21719921

  13. Increased endocytosis and formation of multivesicular bodies in phorbol-ester-stimulated human monoblastic U-937 cells

    SciTech Connect

    Nilsson, M. ); Nilsson, K.; Forsbeck, K. )

    1989-04-01

    The phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) is known to arrest mitotic activity and induce macrophage differentiation in the U-937 monoblastic cell line. The acute effect of TPA on ultrastructural morphology and endocytic activity of U-937 cells was studied. TPA induced within 15 minutes {alpha} marked enlargement of multivesicular bodies (MVBs), comprising both volume and number of inclusion vesicles (other organelles appeared unchanged). At this stage the MVBs frequently showed tubular cytoplasmic extensions. Inclusion vesicles accumulated in MVBs with prolonged incubation (60 minutes). Cellular uptake of {sup 125}I-HRP was increased five times the control values already after 5 minutes of TPA stimulation. The uptake increased further with prolonged incubation (60 minutes), but at a slower rate. Together these indicate a TPA-induced transfer by endocytosis of portions of the plasma membrane to the lysosomal system via MVBs. Consideration of MVBs as part of the receptor-mediated endocytic pathway suggests that this effect of TPA might involve down-regulation of cell-surface receptors. The possibility of MVBs as a proton-sequestrating compartment, responsible for the cytoplasmic alkalinization previously reported for TPA-stimulated U-937 monoblastic cells, is discussed.

  14. Chemoselective Boronic Ester Synthesis by Controlled Speciation**

    PubMed Central

    Fyfe, James W B; Seath, Ciaran P; Watson, Allan J B

    2014-01-01

    Control of boronic acid solution speciation is presented as a new strategy for the chemoselective synthesis of boronic esters. Manipulation of the solution equilibria within a cross-coupling milieu enables the formal homologation of aryl and alkenyl boronic acid pinacol esters. The generation of a new, reactive boronic ester in the presence of an active palladium catalyst also facilitates streamlined iterative catalytic C=C bond formation and provides a method for the controlled oligomerization of sp2-hybridized boronic esters. PMID:25267096

  15. Derivatives of iminomalonic ester

    SciTech Connect

    Prosyanik, A.V.; Fedoseenko, D.V.; Markov, V.I.

    1986-01-10

    The synthesis of (alkylimino)malonic esters was realized by the reaction of alkylamines with mesoxalic or dibromomalonic ester. (Halogenoimino)malonic esters were obtained for the first time by the reaction of aminomalonic ester with tert-butyl hypochlorite or sodium hypobromite. A new method was developed for the synthesis of (acylimino)malonic esters by the successive bromination and dehydrobromination of (acylamino)malonic esters. The addition of various nucleophiles (water, amines, formamide) at the C=N bond of (acylimino)malonic esters was studied.

  16. Novel approaches to analysis of 3-chloropropane-1,2-diol esters in vegetable oils.

    PubMed

    Moravcova, Eliska; Vaclavik, Lukas; Lacina, Ondrej; Hrbek, Vojtech; Riddellova, Katerina; Hajslova, Jana

    2012-03-01

    A sensitive and accurate method utilizing ultrahigh performance liquid chromatography (U-HPLC) coupled to high resolution mass spectrometry based on orbitrap technology (orbitrapMS) for the analysis of nine 3-chloropropane-1,2-diol (3-MCPD) diesters in vegetable oils was developed. To remove the interfering triacylglycerols that induce strong matrix effects, a clean-up step on silica gel column was used. The quantitative analysis was performed with the use of deuterium-labeled internal standards. The lowest calibration levels estimated for the respective analytes ranged from 2 to 5 μg kg(-1). Good recovery values (89-120%) and repeatability (RSD 5-9%) was obtained at spiking levels of 2 and 10 mg kg(-1). As an alternative, a novel ambient desorption ionization technique, direct analysis in real time (DART), hyphenated with orbitrapMS, was employed for no separation, high-throughput, semi-quantitative screening of 3-MCPD diesters in samples obtained by chromatographic fractionation. Additionally, the levels of 3-MCPD diesters measured in reallife vegetable oil samples (palm oil, sunflower oil, rapeseed oil) using both methods are reported. Relatively good agreement of the data generated by U-HPLC-orbitrapMS and DART-orbitrapMS were observed. With regard to a low ionization yield achieved for 3-MCPD monoesters, the methods presented in this paper were not yet applicable for the analysis of these contaminants at the naturally occurring levels. PMID:22287050

  17. Production and biological function of volatile esters in Saccharomyces cerevisiae

    PubMed Central

    Saerens, Sofie M. G.; Delvaux, Freddy R.; Verstrepen, Kevin J.; Thevelein, Johan M.

    2010-01-01

    Summary The need to understand and control ester synthesis is driven by the fact that esters play a key role in the sensorial quality of fermented alcoholic beverages like beer, wine and sake. As esters are synthesized in yeast via several complex metabolic pathways, there is a need to gain a clear understanding of ester metabolism and its regulation. The individual genes involved, their functions and regulatory mechanisms have to be identified. In alcoholic beverages, there are two important groups of esters: the acetate esters and the medium‐chain fatty acid (MCFA) ethyl esters. For acetate ester synthesis, the genes involved have already been cloned and characterized. Also the biochemical pathways and the regulation of acetate ester synthesis are well defined. With respect to the molecular basis of MCFA ethyl ester synthesis, however, significant progress has only recently been made. Next to the characterization of the biochemical pathways and regulation of ester synthesis, a new and more important question arises: what is the advantage for yeast to produce these esters? Several hypotheses have been proposed in the past, but none was satisfactorily. This paper reviews the current hypotheses of ester synthesis in yeast in relation to the complex regulation of the alcohol acetyl transferases and the different factors that allow ester formation to be controlled during fermentation. PMID:21255318

  18. The toxicity of 3-chloropropane-1,2-dipalmitate in Wistar rats and a metabonomics analysis of rat urine by ultra-performance liquid chromatography-mass spectrometry.

    PubMed

    Li, Jianshuang; Wang, Sen; Wang, Maoqing; Shi, Wenxiu; Du, Xiaoyan; Sun, Changhao

    2013-11-25

    3-Monochloropropane-1,2-diol(3-MCPD) fatty acid esters can release free 3-MCPD in a certain condition. Free 3-MCPD is a well-known food contaminant and is toxicological well characterized, however, in contrast to free 3-MCPD, the toxicological characterization of 3-MCPD fatty acid esters is puzzling. In this study, toxicological and metabonomics studies of 3-chloropropane-1,2-dipalmitate(3-MCPD dipalmitate) were carried out based on an acute oral toxicity test, a 90-day feeding test and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. The LD50 value of 3-MCPD dipalmitate was determined to be 1780 mg/kg body weight (bw) for Wistar rats. The results of the 90-day feeding test in male Wistar rats showed that 3-MCPD dipalmitate caused a significant increase in blood urea nitrogen and creatinine in the high-dose group (267 mg/kg bw/day) compared to control rats. Renal tubular epithelium cell degeneration and renal tubular hyaline cast accumulation were the major histopathological changes in rats administered 3-MCPD dipalmitate. Urine samples obtained after the 90-day feeding test and analyzed by UPLC-MS showed that the differences in metabolic profiles between control and treated rats were clearly distinguished by partial least squares-discriminant analysis (PLS-DA) of the chromatographic data. Five metabolite biomarkers which had earlier and significant variations had been identified, they were first considered to be the early, sensitive biomarkers in evaluating the effect of 3-MCPD dipalmitate exposure, and the possible mechanism of these biomarkers variation was elucidated. The combination of histopathological examination, clinical chemistry and metabolomics analyses in rats resulted in a systematic and comprehensive assessment of the long-term toxicity of 3-MCPD dipalmitate. PMID:24140137

  19. Sunflower oil methyl ester as diesel fuel

    SciTech Connect

    Hassett, D.J.; Hasan, R.A.

    1982-01-01

    Methyl ester formation represents one approach to overcome the problems associated with the relatively high viscosity of sunflower oil when used as a diesel fuel replacement. Sunflower oil methyl ester is being prepared at the University of North Dakota Engieering Experiment Station. Physical and chemical properties of this material at varying levels of refinement and purity will be used to define fuel properties. Engine testing is being carried out to determine if the fouling characteristics of methyl ester are significantly less than those of sunflower oil. 1 figure, 1 table.

  20. Wax ester-synthesizing activity of lipases.

    PubMed

    Tsujita, T; Sumiyoshi, M; Okuda, H

    1999-11-01

    The synthesis/hydrolysis of wax esters was studied in an aqueous solution using purified rat pancreatic lipase, porcine pancreatic carboxylester lipase, and Pseudomonas fluorescens lipase. The equilibrium between wax ester synthesis and hydrolysis favored ester formation at neutral pH. The synthesizing activities were measured using free fatty acid or triacylglycerol as the acyl donor and an equimolar amount of long-chain alcohol as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with these lipases, wax ester was synthesized, in a dose- and time-dependent manner, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was about 0.9/0.1. These lipases catalyzed the hydrolysis of palmityl oleate emulsified with gum arabic, and the apparent equilibrium ratio of palmityl oleate/free oleic acid was also about 0.9/0.1. The apparent equilibrium ratio of wax ester/free fatty acid catalyzed by lipase depended on incubation pH and fatty alcohol chain length. When equimolar amounts of trioleoylglycerol and fatty acyl alcohol were incubated with pancreatic lipase, carboxylester lipase, or P. fluorescens lipase, wax esters were synthesized dose-dependently. These results suggest that lipases can catalyze the synthesis of wax esters from free fatty acids or through degradation of triacylglycerol in an aqueous medium. PMID:10606038

  1. Phase behavior and formation of o/w nano-emulsion in vegetable oil/ mixture of polyglycerol polyricinoleate and polyglycerin fatty acid ester/water systems.

    PubMed

    Wakisaka, Satoshi; Nakanishi, Masami; Gohtani, Shoichi

    2014-01-01

    It is reported that mixing polyglycerol polyricinoleate (PGPR) and polyglycerol laurilester has a great emulsifying capacity, and consequently fine oil-in-water (o/w) emulsions can be formed. However, the role of PGPR is not clear. The objective of this research is to investigate the phase behavior of vegetable oil/mixture of PGPR and polyglycerol fatty acid ester/water systems, and to clarify the role of PGPR in making a fine emulsion. Phase diagrams were constructed to elucidate the optimal process for preparing fine emulsions. In all the systems examined in this study, the phases, including the liquid crystal phase (L(c)) and sponge phase (L(3)), spread widely in the phase diagrams. We examined droplet size of the emulsions prepared from each phase and found that o/w nano-emulsions with droplet sizes as small as 50 nm were formed by emulsifying either from a single L(3) phase or a two-phase region, L(c) + L(3). These results indicate that a sponge phase L(3) or liquid crystal phase L(c) or both is necessary to form an o/w nano-emulsion whose average droplet diameter is less than 50 nm for PGPR and polyglycerin fatty acid ester mixtures used as surfactant. PMID:24521844

  2. Oxidative stability of estolide esters using PDSC

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estolides are obtained by the formation of a carbocation that can undergo nucleophilic addition with or without carbocation migration along the length of the chain. The carboxylic acid functionality of one fatty acid links to the site of unsaturation of another fatty acid to form oligomeric esters. ...

  3. 4-Dimenthylaminopyridine or Acid-Catalyzed Synthesis of Esters: A Comparison

    ERIC Educational Resources Information Center

    van den Berg, Annemieke W. C.; Hanefeld, Ulf

    2006-01-01

    A set of highly atom-economic experiments was developed to highlight the differences between acid- and base-catalyzed ester syntheses and to introduce the principles of atom economy. The hydrochloric acid-catalyzed formation of an ester was compared with the 4-dimethylaminopyradine-catalyzed ester synthesis.

  4. Formation of Plant Sterol Oxidation Products in Foods during Baking and Cooking Using Margarine without and with Added Plant Sterol Esters.

    PubMed

    Lin, Yuguang; Knol, Diny; Menéndez-Carreño, María; Blom, Wendy A M; Matthee, Joep; Janssen, Hans-Gerd; Trautwein, Elke A

    2016-01-27

    Plant sterols (PS) in foods are subject to thermal oxidation to form PS oxidation products (POP). This study measured POP contents of 19 foods prepared by typical household baking and cooking methods using margarines without (control) and with 7.5% added PS (as 12.5% PS-esters, PS-margarine). Median POP contents per portion size of cooked foods were 0.57 mg (range 0.05-1.11 mg) with control margarine versus 1.42 mg (range 0.08-20.5 mg) with PS-margarine. The oxidation rate of PS (ORP) was 0.50% (median) with the PS-margarine and 3.66% with the control margarine. Using the PS-margarine, microwave-cooked codfish had the lowest POP content, with 0.08 mg per portion, while shallow-fried potatoes had the highest POP content, 20.5 mg per portion. Median POP contents in cookies, muffins, banana bread, and sponge cake baked with the control or PS-margarine were 0.12 mg (range 0.11-0.21 mg) and 0.24 mg (range 0.19-0.60 mg) per portion, with a corresponding ORP of 1.38% and 0.06%, respectively. POP contents in all the cooked and baked foods did not exceed 20.5 mg per typical portion size. A wide variation in the distribution of individual POP among different foods existed, with 7-keto-PS and 5,6-epoxy-PS being the major oxidation products. PMID:26697919

  5. The Formation Mechanism of Fluorescent Metal Complexes at the LixNi0.5Mn1.5O4-δ/Carbonate Ester Electrolyte Interface

    SciTech Connect

    Jarry, Angelique; Gottis, Sebastien; Yu, Young-Sang; Roque-Rosell, Josep; Kim, Chunjoong; Cabana, Jordi; Kerr, John B; Kostecki, Robert

    2015-03-18

    Electrochemical oxidation of carbonate esters at the LixNi0.5Mn1.5O4-δ/electrolyte interface results in Ni/Mn dissolution and surface film formation, which negatively affect the electrochemical performance of Li-ion batteries. Ex situ X-ray absorption (XRF/XANES), Raman, and fluorescence spectroscopy, along with imaging of LixNi0.5Mn1.5O4-δ positive and graphite negative electrodes from tested Li-ion batteries, reveal the formation of a variety of MnII/III and NiII complexes with β-diketonate ligands. These metal complexes, which are generated upon anodic oxidation of ethyl and diethyl carbonates at LixNi0.5Mn1.5O4-δ, form a surface film that partially dissolves in the electrolyte. The dissolved MnIII complexes are reduced to their MnII analogues, which are incorporated into the solid electrolyte interphase surface layer at the graphite negative electrode. This work elucidates possible reaction pathways and evaluates their implications for Li+ transport kinetics in Li-ion batteries.

  6. Pseudomonas aeruginosa Biofilm Formation and Persistence, along with the Production of Quorum Sensing-Dependent Virulence Factors, Are Disrupted by a Triterpenoid Coumarate Ester Isolated from Dalbergia trichocarpa, a Tropical Legume

    PubMed Central

    Pottier, Laurent; Huet, Joelle; Rabemanantsoa, Christian; Kiendrebeogo, Martin; Andriantsimahavandy, Abel; Rasamindrakotroka, Andry; Stévigny, Caroline; Duez, Pierre; El Jaziri, Mondher

    2015-01-01

    Recently, extracts of Dalbergia trichocarpa bark have been shown to disrupt P. aeruginosa PAO1 quorum sensing (QS) mechanisms, which are key regulators of virulence factor expression and implicated in biofilm formation. One of the active compounds has been isolated and identified as oleanolic aldehyde coumarate (OALC), a novel bioactive compound that inhibits the formation of P. aeruginosa PAO1 biofilm and its maintenance as well as the expression of the las and rhl QS systems. Consequently, the production of QS-controlled virulence factors including, rhamnolipids, pyocyanin, elastase and extracellular polysaccharides as well as twitching and swarming motilities is reduced. Native acylhomoserine lactones (AHLs) production is inhibited by OALC but exogenous supply of AHLs does not restore the production of virulence factors by OALC-treated cultures, indicating that OALC exerts its effect beyond AHLs synthesis in the QS pathways. Further experiments provided a significant inhibition of the global virulence factor activator gacA by OALC. OALC disorganizes established biofilm structure and improves the bactericidal activity of tobramycin against biofilm-encapsulated PAO1 cells. Finally, a significant reduction of Caenorhabditis elegans paralysis was recorded when the worms were infected with OALC-pre-treated P. aeruginosa. Taken together, these results show that triterpenoid coumarate esters are suitable chemical backbones to target P. aeruginosa virulence mechanisms. PMID:26186595

  7. Expanding the modular ester fermentative pathways for combinatorial biosynthesis of esters from volatile organic acids.

    PubMed

    Layton, Donovan S; Trinh, Cong T

    2016-08-01

    Volatile organic acids are byproducts of fermentative metabolism, for example, anaerobic digestion of lignocellulosic biomass or organic wastes, and are often times undesired inhibiting cell growth and reducing directed formation of the desired products. Here, we devised a general framework for upgrading these volatile organic acids to high-value esters that can be used as flavors, fragrances, solvents, and biofuels. This framework employs the acid-to-ester modules, consisting of an AAT (alcohol acyltransferase) plus ACT (acyl CoA transferase) submodule and an alcohol submodule, for co-fermentation of sugars and organic acids to acyl CoAs and alcohols to form a combinatorial library of esters. By assembling these modules with the engineered Escherichia coli modular chassis cell, we developed microbial manufacturing platforms to perform the following functions: (i) rapid in vivo screening of novel AATs for their catalytic activities; (ii) expanding combinatorial biosynthesis of unique fermentative esters; and (iii) upgrading volatile organic acids to esters using single or mixed cell cultures. To demonstrate this framework, we screened for a set of five unique and divergent AATs from multiple species, and were able to determine their novel activities as well as produce a library of 12 out of the 13 expected esters from co-fermentation of sugars and (C2-C6) volatile organic acids. We envision the developed framework to be valuable for in vivo characterization of a repertoire of not-well-characterized natural AATs, expanding the combinatorial biosynthesis of fermentative esters, and upgrading volatile organic acids to high-value esters. Biotechnol. Bioeng. 2016;113: 1764-1776. © 2016 Wiley Periodicals, Inc. PMID:26853081

  8. Kenaf methyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Additional or alternative feedstocks are one of the major areas of interest regarding biodiesel. In this paper, for the first time, the fuel properties of kenaf (Hibiscus cannabinus L.) seed oil methyl esters are comprehensively reported. This biodiesel is also relatively unique by containing small ...

  9. Kapok oil methyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The increased need for biodiesel feedstocks has caused various vegetable oils to be examined for this purpose. In the present work, the methyl esters of kapok (Ceiba pentandra) oil were prepared. The essential fuel properties were comprehensively determined and evaluated in comparison to specificati...

  10. meso-Ester Corroles.

    PubMed

    Canard, Gabriel; Gao, Di; D'Aléo, Anthony; Giorgi, Michel; Dang, Florian-Xuan; Balaban, Teodor Silviu

    2015-05-18

    The introduction of ester groups on the 5- and 15-meso positions of corroles stabilizes them against oxidation and induces a redshift of their absorption and emission spectra. These effects are studied through the photophysical and electrochemical characterization of up to 16 different 5,15-diester corroles, in which the third meso position is free or occupied by an aryl group, a long alkyl chain, or an ester moiety. Single-crystal X-ray structure analysis of five 5,15-diestercorroles and DFT and time-dependent DFT calculations show that the strong electron-withdrawing character of the 5,15 ester substituents is reinforced by their π overlap with the macrocyclic aromatic system. The crystal packing of corroles 2, 4, 6, 9, and 15 features short distances between chromophores that are stacked into columns thanks to the low steric hindrance of meso-ester groups. This close packing is partially due to intermolecular interactions that involve inner hydrogen and nitrogen atoms, and thereby, stabilize a single, identical corrole tautomeric form. PMID:25786789

  11. A pH-responsive drug nanovehicle constructed by reversible attachment of cholesterol to PEGylated poly(l-lysine) via catechol-boronic acid ester formation.

    PubMed

    Yang, Bin; Lv, Yin; Zhu, Jing-Yi; Han, Yun-Tao; Jia, Hui-Zhen; Chen, Wei-Hai; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2014-08-01

    The present work reports the construction of a drug delivery nanovehicle via a pH-sensitive assembly strategy for improved cellular internalization and intracellular drug liberation. Through spontaneous formation of boronate linkage in physiological conditions, phenylboronic acid-modified cholesterol was able to attach onto catechol-pending methoxypoly(ethylene glycol)-block-poly(l-lysine). This comb-type polymer can self-organize into a micellar nanoconstruction that is able to effectively encapsulate poorly water-soluble agents. The blank micelles exhibited negligible in vitro cytotoxicity, yet doxorubicin (DOX)-loaded micelles could effectively induce cell death at a level comparable to free DOX. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the dissociation of the nanoconstruction, which in turn could accelerate the liberation of entrapped drugs. Importantly, the blockage of endosomal acidification in HeLa cells by NH4Cl treatment significantly decreased the nuclear uptake efficiency and cell-killing effect mediated by the DOX-loaded nanoassembly, suggesting that acid-triggered destruction of the nanoconstruction is of significant importance in enhanced drug efficacy. Moreover, confocal fluorescence microscopy and flow cytometry assay revealed the effective internalization of the nanoassemblies, and their cellular uptake exhibited a cholesterol dose-dependent profile, indicating the contribution of introduced cholesterol functionality to the transmembrane process of the nanoassembly. PMID:24879311

  12. The ESTER project

    NASA Astrophysics Data System (ADS)

    Rieutord, M.; Dintrans, B.; Lignières, F.; Corbard, T.; Pichon, B.

    2005-12-01

    The ESTER project aims at building a stellar evolution code in two dimensions of space for the study of effects of rotation. The numerical scheme is based on spectral methods with a spherical harmonic decomposition in the horizontal direction and a Chebyshev polynomial expansion in the vertical direction. Coordinates adapted to the centrifugally distorted shape are mapped to spherical coordinates. First tests on rotating polytropes are presented.

  13. Significant enhancement of 11-Hydroxy-THC detection by formation of picolinic acid esters and application of liquid chromatography/multi stage mass spectrometry (LC-MS(3) ): Application to hair and oral fluid analysis.

    PubMed

    Thieme, Detlef; Sachs, Ulf; Sachs, Hans; Moore, Christine

    2015-07-01

    Formation of picolinic acid esters of hydroxylated drugs or their biotransformation products is a promising tool to improve their mass spectrometric ionization efficiency, alter their fragmentation behaviour and enhance sensitivity and specificity of their detection. The procedure was optimized and tested for the detection of cannabinoids, which proved to be most challenging when dealing with alternative specimens, for example hair and oral fluid. In particular, the detection of the THC metabolites hydroxyl-THC and carboxy-THC requires ultimate sensitivity because of their poor incorporation into hair or saliva. Both biotransformation products are widely accepted as incorporation markers to distinguish drug consumption from passive contamination. The derivatization procedure was carried out by adding a mixture of picolinic acid, 4-(dimethylamino)pyridine and 2-methyl-6-nitrobenzoic anhydride in tetrahydrofuran/triethylamine to the dry extraction residues. Resulting derivatives were found to be very stable and could be reconstituted in aqueous or organic buffers and subsequently analyzed by liquid chromatography-mass spectrometry (LC-MS). Owing to the complex consecutive fragmentation patterns, the application of multistage MS3 proved to be extremely useful for a sensitive identification of doubly picolinated hydroxy-THC in complex matrices. The detection limits - estimated by comparison of corresponding signal-to-noise ratios - increased by a factor of 100 following picolination. All other species examined, like cannabinol, THC, cannabidiol, and carboxy-THC, could also be derivatized exhibiting only moderate sensitivity improvements. The assay was systematically tested using hair samples and exemplarily applied to oral fluid. Concentrations of OH-THC identified in THC-positive hair samples ranged from 0.02 to 0.29pg/mg. PMID:25345394

  14. Method of making alkyl esters

    DOEpatents

    Elliott, Brian

    2010-09-14

    Methods of making alkyl esters are described herein. The methods are capable of using raw, unprocessed, low-cost feedstocks and waste grease. Generally, the method involves converting a glyceride source to a fatty acid composition and esterifying the fatty acid composition to make alkyl esters. In an embodiment, a method of making alkyl esters comprises providing a glyceride source. The method further comprises converting the glyceride source to a fatty acid composition comprising free fatty acids and less than about 1% glyceride by mass. Moreover, the method comprises esterifying the fatty acid composition in the presence of a solid acid catalyst at a temperature ranging firm about 70.degree. C. to about 120.degree. C. to produce alkyl esters, such that at least 85% of the free fatty acids are converted to alkyl esters. The method also incorporates the use of packed bed reactors for glyceride conversion and/or fatty acid esterification to make alkyl esters.

  15. Electron driven processes in chlorodifluoroacetic acid methyl ester

    NASA Astrophysics Data System (ADS)

    Kopyra, Janina

    2014-07-01

    Dissociative electron attachment to gas phase 2-chloro-2,2-difluoroacetic acid methyl ester (CClF2COOCH3) is studied by means of a crossed beams apparatus. Effective cleavage of the C-Cl bond is observed within a broad resonance in the energy range 0-1 eV and visible via the appearance of the light fragment Cl-. In chlorodifluoroacetic acid cleavage of the C-Cl bond was observed not only via the Cl- anion formation but predominantly via expulsion of the neutral chlorine atom leading to the formation of the (M-Cl)- anion. Similar to the previously studied esters CF3COOCH3 and CF3COOC2H5[I. Martin, J. Langer, E. Illenberger, Z. Phys. Chem. 222, 1185 (2008)], we observe reaction due to the cleavage of the ester bond resulting in the formation of the closed shell (M-CH3)- anion.

  16. Lipoate ester multifunctional lubricant additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven lipoate esters were synthesized by esterification of lipoic acid with different structures of alcohols in the presence of a solid acid catalyst and without solvent. The esters were obtained in good yield, characterized using 1H NMR and GPC; and their physical properties investigated. Four of t...

  17. Synthesis of pyromellitic acid esters

    NASA Technical Reports Server (NTRS)

    Fedorova, V. A.; Donchak, V. A.; Martynyuk-Lototskaya, A. N.

    1985-01-01

    The ester acids necessary for studyng the thermochemical properties of pyromellitic acid (PMK)-based peroxides were investigated. Obtaining a tetramethyl ester of a PMK was described. The mechanism of an esterification reaction is discussed, as is the complete esterification of PMK with primary alcohol.

  18. Synthesis of some glucose-fatty acid esters by lipase from Candida antarctica and their emulsion functions.

    PubMed

    Ren, Kangzi; Lamsal, Buddhi P

    2017-01-01

    The synthesis of glucose esters with palmitic acid, lauric acid and hexanoic acid using lipase enzyme was studied and their emulsion functionality in oil-in-water system were compared. Reactions at 3:1M ratio of fatty acids-to-glucose had the highest conversion percentages (over 90% for each of the fatty acid). Initial conversion rate increased as substrate solubility increased. Ester bond formation was confirmed by nuclear magnetic resonance technique that the chemical shifts of glucose H-6 and α-carbon protons of fatty acids in the ester molecules shifted to the higher fields. Contact angle of water on esters' pelleted surface increased as the hydrophobicity increased. Glucose esters' and commercial sucrose esters' functionality as emulsifiers were compared. Glucose esters delayed, but did not prevent coalescence, because the oil droplets diameter doubled during 7days. Sucrose esters prevented coalescence during 7days since the droplets diameter did not have significant change. PMID:27507510

  19. The polymorphic and mesomorphic behavior of four esters of cholesterol.

    NASA Technical Reports Server (NTRS)

    Merritt, W. G.; Cole, G. D.; Walker, W. W.

    1971-01-01

    The techniques of differential scanning calorimetry, X-ray powder diffractometry, and positron annihilation have been used to study the polymorphic and mesomorphic behavior of the following esters of cholesterol: cholesteryl formate, cholesteryl butyrate, cholesteryl benzoate, and cholesteryl cinnamate. Each of these compounds exhibits a single mesophase of the cholesteric type. The solid phase formed from the melt for each ester was observed to be structurally different from the solid phase obtained from solution. Solvents from which the solution-grown samples were crystallized were as follows: cholesteryl formate and cholesteryl butyrate from acetone, cholesteryl benzoate from benzene, and cholesteryl cinnamate from 2-butanone.

  20. New lipophilic tyrosyl esters. Comparative antioxidant evaluation with hydroxytyrosyl esters.

    PubMed

    Mateos, Raquel; Trujillo, Mariana; Pereira-Caro, Gema; Madrona, Andrés; Cert, Arturo; Espartero, José Luis

    2008-11-26

    New lipophilic esters of tyrosol, a naturally occurring phenol with interesting biological properties, have been synthesized in good yields by a chemoselective procedure, using lipase from Candida antarctica or p-toluenesulfonic acid as catalysts. Their antioxidant activities have been evaluated by the Rancimat test in lipophilic food matrices, as well as by FRAP and ABTS assays in methanolic solutions, and compared with those of previously synthesized hydroxytyrosyl esters. Free tyrosol, hydroxytyrosol, butylhydroxytoluene, and alpha-tocopherol were used as standards. All methods used for the antioxidant activity evaluation emphasized the high influence of the ortho-diphenolic structure on the antioxidant capacity, tyrosol and its derivatives being less active than hydroxytyrosol and its analogues and even less than BHT and alpha-tocopherol. In addition, the Rancimat test revealed a lower activity for ester derivatives than for their respective reference compounds (HTy or Ty), in agreement with the polar paradox. On the other hand, FRAP and ABTS methods reported an opposite behavior between the synthetic esters and their respective references. Thus, hydroxytyrosyl esters were more active than HTy, whereas tyrosyl esters were less active than Ty. The length and nature of the acyl side chain did not seem to play an important role in the antioxidant activity of either the hydroxytyrosyl or tyrosyl ester series, since no significant differences were observed among them. PMID:18983160

  1. Anaerobic biodegradation of methyl esters by Acetobacterium woodii and Eubacterium limosum.

    PubMed

    Liu, S; Suflita, J M

    1994-09-01

    The ability of Acetobacterium woodii and Eubacterium limosum to degrade methyl esters of acetate, propionate, butyrate, and isobutyrate was examined under growing and resting-cell conditions. Both bacteria hydrolyzed the esters to the corresponding carboxylates and methanol under either condition. Methanol was further oxidized to formate under growing but not resting conditions. Unlike the metabolism of phenylmethylethers, no H2 requirement was evident for ester biotransformation. The hydrolysis of methyl carboxylates is thermodynamically favorable under standard conditions and the mixotrophic metabolism of ester/CO2 allowed for bacterial growth. These results suggest that the degradation of methyl carboxylates may be a heretofore unrecognized nutritional option for acetogenic bacteria. PMID:7765371

  2. Impact of Association Colloids on Lipid Oxidation in Triacylglycerols and Fatty Acid Ethyl Esters.

    PubMed

    Homma, Rika; Suzuki, Karin; Cui, Leqi; McClements, David Julian; Decker, Eric A

    2015-11-25

    The impact of association colloids on lipid oxidation in triacylglycerols and fatty acid ethyl esters was investigated. Association colloids did not affect lipid oxidation of high oleic safflower and high linoleic safflower triacylglycerols, but were prooxidative in fish triacylglycerols. Association colloids retarded aldehyde formation in stripped ethyl oleate, linoleate, and fish oil ethyl esters. Interfacial tension revealed that lipid hydroperoxides were surface active in the presence of the surfactants found in association colloids. The lipid hydroperoxides from ethyl esters were less surface active than triacylglycerol hydroperoxides. Stripping decreased iron and copper concentrations in all oils, but more so in fatty acid ethyl esters. The combination of lower hydroperoxide surface activity and low metal concentrations could explain why association colloids inhibited lipid oxidation in fatty acid ethyl esters. This research suggests that association colloids could be used as an antioxidant technology in fatty acid ethyl esters. PMID:26506263

  3. Mechanism of CO{sub 2} corrosion inhibition by phosphate esters

    SciTech Connect

    Alin, B.; Outlaw, B.; Jovancicevic, V.; Ramachandran, S.; Campbell, S.

    1999-11-01

    The mechanisms of corrosion inhibition of mild steel by phosphate esters in a CO{sub 2} containing environment is studied by using various inhibitor solution characterization techniques (residual analysis, dynamic surface tension, emulsion tendency). Corrosion inhibition and inhibitor film persistence is monitored over time by using a rotating cylinder electrode (RCE) system and linear polarization resistance (LPR) technique. Corrosion rate-time/concentration profiles are obtained for all phosphate esters studied. Optical profilometry is used to assess surface microstructure as related to inhibitor film persistence. The effect of phosphate ester`s chemical structure (aromatic vs. aliphatic hydrophobic group, degree of ethoxylation, mono- vs. di-ester) on inhibitor performance is investigated in terms of their volubility, hydrolytic stability, emulsion properties, iron/calcium salt/complex formation and oil/water partitioning. A synergy between phosphate esters and imidazolines is also investigated.

  4. Polyurethane foams based on crude glycerol-derived biopolyols: One-pot preparation of biopolyols with branched fatty acid ester chains and its effects on foam formation and properties

    SciTech Connect

    Li, Cong; Luo, Xiaolan; Li, Tao; Tong, Xinjie; Li, Yebo

    2014-01-01

    Environmentally friendly biopolyols have been produced with crude glycerol as the sole feedstock using a one-pot thermochemical conversion process without the addition of extra catalysts and reagents. Structural features of these biopolyols were characterized by rheology analysis. Rigid polyurethane (PU) foams were obtained from these crude glycerol-based biopolyols and the foaming mechanism was explored. Investigations revealed that partial carbonyl groups hydrogen-bonded with NeH were replaced by aromatic rings after the introduction of branched fatty acid ester chains in the “urea rich” phase, and that distinct microphases had formed in the foams. Studies showed that branched fatty acid ester chains in the biopolyols played an important role in reducing the degree of microphase separation and stabilizing bubbles during foaming processes. PU foams with thermal conductivity comparable to commercial products made from petroleum-based polyols were obtained. These studies show the potential for development of PU foams based on crude glycerol, a renewable resource.

  5. Acrylic esters in radiation polymerization

    SciTech Connect

    Fomina, N.V.; Khoromskaya, V.A.; Shiryaeva, G.V.

    1988-03-01

    The radiation behavior of (meth)acrylic esters of varying structure was studied. It was shown that in radiation polymerization, in contrast to thermal polymerization, the structure of the ester part can significantly affect the reaction rate and capacity for polymerization in the presence of oxygen. The experimental data are explained from the point of view of consideration of nonvalence effects of the substitutent on the reactivity of the double bond.

  6. FTIR studies of hydrogen bonding between α,β-unsaturated esters and alcohols

    NASA Astrophysics Data System (ADS)

    Tonge, P. J.; Fausto, R.; Carey, P. R.

    1996-06-01

    The enthalpy (and entropy) of hydrogen bond formation has been measured between the ester carbonyl groups of the two α,β-unsaturated esters thienylacryloyl (TAOMe) and 5-methylthienylacryloyl (5MeTAOMe) methyl ester and the hydrogen bond donors ethanol, phenol and 3,5-dichlorophenol in CCl 4. For the esters, the hydrogen bonding strengths were measured by quantitating the amount of bound and unbound donor, using the OH stretching region, as a function of temperature and applying the van't Hoff equation. The decrease in νCO of the ester carbonyl group upon hydrogen bond formation ΔνCO has also been measured and correlated with the enthalpy of hydrogen bond formation. A linear correlation is observed between the enthalpy of hydrogen bond formation - ΔH and ΔνCO, with - ΔH = 1.36 ΔνCO - 16.1, where ΔH is measured in kJ mol -1 and Δν in cm -1. Comparison with data for other carbonyl acceptor compounds indicates that the carbonyl group of the above α,β-unsaturated esters is more readily polarized than the carbonyl group of saturated esters or ketones. The quantitative relationship between - ΔH and ΔνCO derived here has been used to determine the change in the enthalpy of hydrogen bond formation between substrate and enzyme groups in a series of acylserine proteases.

  7. Fatty acid alcohol ester-synthesizing activity of lipoprotein lipase.

    PubMed

    Tsujita, T; Sumiyoshi, M; Okuda, H

    1999-12-01

    The fatty acid alcohol ester-synthesizing activity of lipoprotein lipase (LPL) was characterized using bovine milk LPL. Synthesizing activities were determined in an aqueous medium using oleic acid or trioleylglycerol as the acyl donor and equimolar amounts of long-chain alcohols as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with LPL, palmityl oleate was synthesized, in a time- and dose-dependent manner. Apo-very low density lipoprotein (apoVLDL) stimulated LPL-catalyzed palmityl oleate synthesis. The apparent equilibrium ratio of fatty acid alcohol ester/oleic acid was estimated using a high concentration of LPL and a long (20 h) incubation period. The equilibrium ratio was affected by the incubation pH and the alcohol chain length. When the incubation pH was below pH 7.0 and long chain fatty acyl alcohols were used as substrates, the fatty acid alcohol ester/free fatty acid equilibrium ratio favored ester formation, with an apparent equilibrium ratio of fatty acid alcohol ester/fatty acid of about 0.9/0.1. The equilibrium ratio decreased sharply at alkaline pH (above pH 8.0). The ratio also decreased when fatty alcohols with acyl chains shorter than dodecanol were used. When a trioleoylglycerol/fatty acyl alcohol emulsion was incubated with LPL, fatty acid alcohol esters were synthesized in a dose- and time-dependent fashion. Fatty acid alcohol esters were easily synthesized from trioleoylglycerol when fatty alcohols with acyl chains longer than dodecanol were used, but synthesis was decreased with fatty alcohols with acyl chain lengths shorter than decanol, and little synthesizing activity was detected with shorter-chain fatty alcohols such as butanol or ethanol. PMID:10578059

  8. Inhibitors for cholesterol ester accumulation in macrophages from Chinese cabbage.

    PubMed

    Takamoto, Haruka; Eguchi, Keisuke; Kawabata, Tetsuro; Fujiwara, Yukio; Takeya, Motohiro; Tsukamoto, Sachiko

    2015-01-01

    The cholesterol ester accumulates in macrophages in the early stage of atherosclerotic lesions, leading to the formation of foam cells. We examined the inhibitory effects of the crude extracts of 22 edible plants on foam cell formation and isolated nine chlorophyll derivatives as potent inhibitors from Chinese cabbage. The results of the present study suggest that the chlorophyll derivatives contained in edible plants may be useful for the prevention and treatment of atherosclerosis. PMID:25776101

  9. Encapsulating fatty acid esters of bioactive compounds in starch

    NASA Astrophysics Data System (ADS)

    Lay Ma, Ursula Vanesa

    Interest in the use of many bioactive compounds in foods is growing in large part because of the apparent health benefits of these molecules. However, many of these compounds can be easily degraded during processing, storage, or their passage through the gastrointestinal tract before reaching the target site. In addition, they can be bitter, acrid, or astringent, which may negatively affect the sensory properties of the product. Encapsulation of these molecules may increase their stability during processing, storage, and in the gastrointestinal tract, while providing controlled release properties. The ability of amylose to form inclusion complexes and spherulites while entrapping certain compounds has been suggested as a potential method for encapsulation of certain molecules. However, complex formation and spherulitic crystallization are greatly affected by the type of inclusion molecules, type of starch, and processing conditions. The objectives of the present investigation were to: (a) study the effect of amylose, amylopectin, and intermediate material on spherulite formation and its microstructure; (b) investigate the formation of amylose and high amylose starch inclusion complexes with ascorbyl palmitate, retinyl palmitate, and phytosterol esters; (c) evaluate the ability of spherulites to form in the presence of fatty acid esters and to entrap ascorbyl palmitate, retinyl palmitate, and phytosterol esters; and (d) evaluate the effect of processing conditions on spherulite formation and fatty acid ester entrapment. Higher ratios of linear to branched molecules resulted in the formation of more and rounder spherulites with higher heat stability. In addition to the presence of branches, it appears that spherulitic crystallization is also affected by other factors, such as degree of branching, chain length, and chain length distribution. Amylose and Hylon VII starch formed inclusion complexes with fatty acid esters of ascorbic acid, retinol, or phytosterols

  10. Fiberite 954: cyanate ester systems

    NASA Astrophysics Data System (ADS)

    Almen, G. R.; Mackenzie, P. D.; Malhotra, Vinay; Maskell, R. K.

    1992-09-01

    Cost and weight savings achieved by the use of composites have allowed these materials to displace their metal counterparts in space applications. Epoxy matrix based carbon fiber reinforced composites, such as Fiberite 934, have been used for a number of years. Relative to these systems, cyanate esters offer a number of unique attributes such as excellent hydrophobicity and electrical properties, reduced residual stress and better microcrack resistance, and improved radiation resistance. The significant reduction in water sorption and the low response to uptake make it possible to achieve much improved dimensional stability and reduced outgassing. These features may be used to advantage in electro-optical applications in space. ICI Fiberite has developed cyanate ester based prepreg systems that are penetrating the satellite, military radome and structural aerospace markets. Features of these systems will be presented and the properties of the cyanate ester based prepreg, Fiberite 954- 3, will be compared to those of Fiberite 934.

  11. A Comparison Study: The New Extended Shelf Life Isopropyl Ester PMR Technology versus The Traditional Methyl Ester PMR Approach

    NASA Technical Reports Server (NTRS)

    Alston, William B.; Scheiman, Daniel A.; Sivko, Gloria S.

    2005-01-01

    Polymerization of Monomeric Reactants (PMR) monomer solutions and carbon cloth prepregs of PMR II-50 and VCAP-75 were prepared using both the traditional limited shelf life methanol based PMR approach and a novel extended shelf life isopropanol based PMR approach. The methyl ester and isopropyl ester based PMR monomer solutions and PMR prepregs were aged for up to four years at freezer and room temperatures. The aging products formed were monitored using high pressure liquid chromatography (HPLC). The composite processing flow characteristics and volatile contents of the aged prepregs were also correlated versus room temperature storage time. Composite processing cycles were developed and six ply cloth laminates were fabricated with prepregs after various extended room temperature storage times. The composites were then evaluated for glass transition temperature (Tg), thermal decomposition temperature (Td), initial flexural strength (FS) and modulus (FM), long term (1000 hours at 316 C) thermal oxidative stability (TOS), and retention of FS and FM after 1000 hours aging at 316 C. The results for each ester system were comparable. Freezer storage was found to prevent the formation of aging products for both ester systems. Room temperature storage of the novel isopropyl ester system increased PMR monomer solution and PMR prepreg shelf life by at least an order of magnitude while maintaining composite properties.

  12. Synthesis and properties of differently charged chemiluminescent acridinium ester labels.

    PubMed

    Natrajan, Anand; Sharpe, David

    2013-02-14

    Chemiluminescent acridinium dimethylphenyl esters containing N-sulfopropyl groups in the acridinium ring are highly sensitive, hydrophilic labels that are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of a cationic surfactant. At physiological pH, N-sulfopropyl acridinium esters exist as water adducts that are commonly referred to as pseudobases. Pseudobase formation, which results from addition of water to the zwitterionic N-sulfopropyl acridinium ring, neutralizes the positive charge on the acridinium nitrogen and imparts a net negative charge to the label due to the sulfonate moiety. As a consequence, N-sulfopropyl acridinium ester conjugates of small molecule haptens as well as large molecules such as proteins gain negative charges at neutral pH. In the current study, we describe the synthesis and properties of two new hydrophilic acridinium dimethylphenyl ester labels where the net charge in the labels was altered. In one label, the structure of the hydrophilic N-alkyl group attached to the acridinium ring was changed so that the pseudobase of the label contains no net charge. In the second acridinium ester, two additional negative charges in the form of sulfopropyl groups were added to the acridinium ring to make this label's pseudobase strongly anionic. Chemiluminescence measurements of these labels, as well as their conjugates of an antibody with a neutral pI, indicate that acridinium ester charge while having a modest effect on emission kinetics has little influence on light output. However, our results demonstrate that acridinium ester charge can affect protein pI, apparent chemiluminescence stability and non-specific binding of protein conjugates to microparticles. These results emphasize the need for careful consideration of acridinium ester charge in order to optimize reagent stability and performance in immunoassays. In the current study, we observed that

  13. Synthesis and Utility of Dihydropyridine Boronic Esters.

    PubMed

    Panda, Santanu; Coffin, Aaron; Nguyen, Q Nhu; Tantillo, Dean J; Ready, Joseph M

    2016-02-01

    When activated by an acylating agent, pyridine boronic esters react with organometallic reagents to form a dihydropyridine boronic ester. This intermediate allows access to a number of valuable substituted pyridine, dihydropyridine, and piperidine products. PMID:26694785

  14. Liquid Crystalline Thermosets from Ester, Ester-imide, and Ester-amide Oligomers

    NASA Technical Reports Server (NTRS)

    Dingemans, Theodorus J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

    2009-01-01

    Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystaloligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oli-gomers are stable forup to an hour in the melt phase. They are highly processable by a variety of melt process shape forming and blending techniques. Once processed and shaped, the end-capped liquid crystal oigomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures.

  15. REPRODUCTIVE TOXICITY OF PHTHALATE ESTERS

    EPA Science Inventory

    Phthalate esters display several modes of toxicity in mammalian species. In the rat, in utero exposure at relatively low dosage levels disrupts development of the reproductive system of the male rat by altering fetal testis hormone production. This presentation is a review of t...

  16. Trimerization of Phenyl Cyanate Ester

    NASA Astrophysics Data System (ADS)

    Pallaka, Madhusudhan Reddy; Simon, Sindee L.

    2015-03-01

    The kinetics of phenyl cyanate ester trimerization is studied in the bulk using differential scanning calorimetry. Dynamic experiments for different heating rates are analyzed for the activation energy using the model-free Kissinger-Akahira-Sunose(KAS) isoconversion method. The activation energy and other kinetic parameters are also obtained by fitting the dynamic data to a first order autocatalytic reaction model, which well describes the experimental data. The activation energy obtained from the KAS isoconversion method (70.1 kJ/mol) is in good agreement with that obtained from the kinetic model (73.2 kJ/mol) and is much lower than the more bulky cyanate esters studied in our laboratory, which have activation energies of approximately 95 kJ/mol. In addition, the rate constant for the phenyl cyanate ester is one to two orders higher than the bulkier cyanate esters in the temperature range of 200 to 300°C. Further elucidation of the dynamic experiments revealed a strong dependence of the reaction kinetics on the sample weight. Future work aims to understand this finding.

  17. Biodiesel With Optimized Fatty Ester Composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is largely composed of the mono-alkyl esters, usually methyl esters, of vegetable oils or animal fats with its fatty acid profile corresponding to that of the parent oil or fat. The different fatty esters have varying properties of relevance to biodiesel. The feedstock-dependent variatio...

  18. 40 CFR 721.2805 - Acrylate ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Acrylate ester. 721.2805 Section 721... Acrylate ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an acrylate ester (PMN P-96-824) is subject to reporting under...

  19. 40 CFR 721.3034 - Methylamine esters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Methylamine esters. 721.3034 Section... Substances § 721.3034 Methylamine esters. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as methylamine esters (PMN P-94-982) is...

  20. 40 CFR 721.3034 - Methylamine esters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Methylamine esters. 721.3034 Section... Substances § 721.3034 Methylamine esters. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as methylamine esters (PMN P-94-982) is...

  1. 40 CFR 721.2805 - Acrylate ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Acrylate ester. 721.2805 Section 721... Acrylate ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an acrylate ester (PMN P-96-824) is subject to reporting under...

  2. Direct transformation of esters into arenes with 1,5-bifunctional organomagnesium reagents.

    PubMed

    Link, Achim; Fischer, Christian; Sparr, Christof

    2015-10-01

    A direct transformation of carboxylic acid esters into arenes with 1,5-bifunctional organomagnesium reagents is described. This efficient and practical method enables the one-step defunctionalization of various carboxylic acid esters to prepare benzene, anthracene, tetracene, and pentacene derivatives. A double nucleophilic addition of the 1,5-organodimagnesium reagent to the ester is followed by an immediate 1,4-elimination reaction that leads to the direct [5+1] formation of a new aromatic ring. PMID:26291060

  3. Enantiospecific Alkynylation of Alkylboronic Esters

    PubMed Central

    Wang, Yahui; Noble, Adam; Myers, Eddie L.

    2016-01-01

    Abstract Enantioenriched secondary and tertiary alkyl pinacolboronic esters undergo enantiospecific deborylative alkynylation through a Zweifel‐type alkenylation followed by a 1,2‐elimination reaction. The process involves use of α‐lithio vinyl bromide or vinyl carbamate species, for which application to Zweifel‐type reactions has not previously been explored. The resulting functionalized 1,1‐disubstituted alkenes undergo facile base‐mediated elimination to generate terminal alkyne products in high yield and excellent levels of enantiospecificity over a wide range of pinacolboronic ester substrates. Furthermore, along with terminal alkynes, internal and silyl‐protected alkynes can be formed by simply introducing a suitable carbon‐ or silicon‐based electrophile after the base‐mediated 1,2‐elimination reaction. PMID:26934427

  4. ESTER: Evolution STEllaire en Rotation

    NASA Astrophysics Data System (ADS)

    Rieutord, Michel

    2013-05-01

    The ESTER code computes the steady state of an isolated star of mass larger than two solar masses. The only convective region computed as such is the core where isentropy is assumed. ESTER provides solutions of the partial differential equations, for the pressure, density, temperature, angular velocity and meridional velocity for the whole volume. The angular velocity (differential rotation) and meridional circulation are computed consistently with the structure and are driven by the baroclinic torque. The code uses spectral methods, both radially and horizontally, with spherical harmonics and Chebyshev polynomials. The iterations follow Newton's algorithm. The code is object-oriented and is written in C++; a python suite allows an easy visualization of the results. While running, PGPLOT graphs are displayed to show evolution of the iterations.

  5. Segmented polyether-ester copolymers

    SciTech Connect

    Souffie, R.D.

    1982-08-01

    This article touches on the chemistry of manufacture and structure of thermoplastic elastomers. The physical properties and environmental resistance characteristics of these copolymers are related to their molecular makeup. Results indicate that segmented polyether esters, because of their basic chemical structure, are resistant to a wide range of oils, solvents and chemicals. They are also highly elastic, resilient polymers which can be both cost and performance effective when used in a number of industrial applications.

  6. Methods of making alkyl esters

    DOEpatents

    Elliott, Brian

    2010-08-03

    A method comprising contacting an alcohol, a feed comprising one or more glycerides and equal to or greater than 2 wt % of one or more free fatty acids, and a solid acid catalyst, a nanostructured polymer catalyst, or a sulfated zirconia catalyst in one or more reactors, and recovering from the one or more reactors an effluent comprising equal to or greater than about 75 wt % alkyl ester and equal to or less than about 5 wt % glyceride.

  7. Requirement of catalytic-triad and related amino acids for the acyltransferase activity of Tanacetum cinerariifolium GDSL lipase/esterase TcGLIP for ester-bond formation in pyrethrin biosynthesis.

    PubMed

    Kikuta, Yukio; Yamada, Gen; Mitsumori, Tomonori; Takeuchi, Takayuki; Nakayama, Koji; Katsuda, Yoshio; Hatanaka, Akikazu; Matsuda, Kazuhiko

    2013-01-01

    We have recently discovered that a GDSL lipase/esterase (TcGLIP) in Tanacetum cinerariifolium catalyzed acyltransferase activity to form an ester bond in the natural insecticide, pyrethrin. TcGLIP contained Ser40 in Block I, Gly64 in Block II, Asn168 in Block III and Asp318 and His321 in Block V, suggesting underlying hydrolase activity, although little is known about their role in acyltransferase activity. We expressed TcGLIP here in Esherichia coli as a fusion with maltose-binding protein (MBP), part of the fusion being cleaved with a protease to obtain MBP-free TcGLIP. A kinetic analysis revealed that the MBP moiety scarcely influenced the kinetic parameters. The effects on acyltransferase activity of mutations of Gly64, Asn168, Asp318 and His321 were investigated by using MBP-fused TcGLIP. Mutations of these amino acids markedly reduced the acyltransferase activity, suggesting their critical role in the production of pyrethrins. PMID:24018659

  8. Liquid Crystalline Thermosets from Ester, Ester-Imide, and Ester-Amide Oligomers

    NASA Technical Reports Server (NTRS)

    Dingemans, Theodornus J. (Inventor); Weiser, Erik S. (Inventor); SaintClair, Terry L. (Inventor)

    2005-01-01

    Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and were end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting reactive end-capped liquid crystal oligomers exhibit a variety of improved and preferred physical properties. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,OOO grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oligomers are stable for up to an hour in the melt phase. These properties make the end-capped liquid crystal oligomers highly processable by a variety of melt process shape forming and blending techniques including film extrusion, fiber spinning, reactive injection molding (RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding, pultrusion, injection molding, blow molding, plasma spraying and thermo-forming. Once processed and shaped, the end- capped liquid crystal oligomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures. The resulting thermosets display many properties that are superior to their non-end-capped high molecular weight analogs.

  9. Liquid crystalline thermosets from ester, ester-imide, and ester-amide oligomers

    NASA Technical Reports Server (NTRS)

    Dingemans, Theodorous J. (Inventor); Weiser, Erik S. (Inventor); St. Clair, Terry L. (Inventor)

    2005-01-01

    Main chain thermotropic liquid crystal esters, ester-imides, and ester-amides were prepared from AA, BB, and AB type monomeric materials and were end-capped with phenylacetylene, phenylmaleimide, or nadimide reactive end-groups. The resulting reactive end-capped liquid crystal oligomers exhibit a variety of improved and preferred physical properties. The end-capped liquid crystal oligomers are thermotropic and have, preferably, molecular weights in the range of approximately 1000-15,000 grams per mole. The end-capped liquid crystal oligomers have broad liquid crystalline melting ranges and exhibit high melt stability and very low melt viscosities at accessible temperatures. The end-capped liquid crystal oligomers are stable for up to an hour in the melt phase. These properties make the end-capped liquid crystal oligomers highly processable by a variety of melt process shape forming and blending techniques including film extrusion, fiber spinning, reactive injection molding (RIM), resin transfer molding (RTM), resin film injection (RFI), powder molding, pultrusion, injection molding, blow molding, plasma spraying and thermo-forming. Once processed and shaped, the end-capped liquid crystal oligomers were heated to further polymerize and form liquid crystalline thermosets (LCT). The fully cured products are rubbers above their glass transition temperatures. The resulting thermosets display many properties that are superior to their non-end-capped high molecular weight analogs.

  10. Determination of 13C isotopic enrichment of valine and threonine by GC-C-IRMS after formation of the N(O,S)-ethoxycarbonyl ethyl ester derivatives of the amino acids.

    PubMed

    Godin, Jean-Philippe; Faure, Magali; Breuille, Denis; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2007-06-01

    We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers ((13)C-valine or (13)C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at natural abundance and at low (13)C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5% at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32 per thousand. The (13)C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis. PMID:17468859

  11. Production of wax esters in plant seed oils by oleosomal cotargeting of biosynthetic enzymes[S

    PubMed Central

    Heilmann, Mareike; Iven, Tim; Ahmann, Katharina; Hornung, Ellen; Stymne, Sten; Feussner, Ivo

    2012-01-01

    Wax esters are neutral lipids exhibiting desirable properties for lubrication. Natural sources have traditionally been whales. Additionally some plants produce wax esters in their seed oil. Currently there is no biological source available for long chain length monounsaturated wax esters that are most suited for industrial applications. This study aimed to identify enzymatic requirements enabling their production in oilseed plants. Wax esters are generated by the action of fatty acyl-CoA reductase (FAR), generating fatty alcohols and wax synthases (WS) that esterify fatty alcohols and acyl-CoAs to wax esters. Based on their substrate preference, a FAR and a WS from Mus musculus were selected for this study (MmFAR1 and MmWS). MmWS resides in the endoplasmic reticulum (ER), whereas MmFAR1 associates with peroxisomes. The elimination of a targeting signal and the fusion to an oil body protein yielded variants of MmFAR1 and MmWS that were cotargeted and enabled wax ester production when coexpressed in yeast or Arabidopsis. In the fae1 fad2 double mutant, rich in oleate, the cotargeted variants of MmFAR1 and MmWS enabled formation of wax esters containing >65% oleyl-oleate. The data suggest that cotargeting of unusual biosynthetic enzymes can result in functional interplay of heterologous partners in transgenic plants. PMID:22878160

  12. Anti-friction properties of ester additives during hot rolling of aluminum{copyright}

    SciTech Connect

    Januszkiewicz, K.R.; Bekmesian, G.; Heenan, D.F.

    1995-08-01

    Heavy esters of polyhydric alcohols, such as glycerol and synthetic polyols, are commonly used as additives in aluminum hot rolling lubricants. The presence of several hydroxyl groups allows a varying degree of esterification leading to the formation of full and partial esters. These esters are rarely separated from the main additive, and thus may be present in the finished rolling lubricant, affecting its anti-friction properties. The objective of this work was to examine the anti-friction properties of these potential ester contaminants during rolling on a laboratory hot rolling mill. Two lubricant application methods were examined; as emulsion and direct (neat oil) application. The anti-friction properties of additives were found to depend on their chemical structure and the lubricant applications method. In emulsified oils, partial esters of glycerol were found to greatly reduce friction in comparison to triglycerides, while the partial esters of synthetic polyols exhibited only a weak anti-friction effect. There was no frictional advantage observed which could be associated with using the partial esters in direct application mode. Moreover, under these conditions, the anti-friction properties of the completely esterified synthetic polyols were significantly lower than those of triglycerides, while in emulsions they were comparable. 11 refs., 7 figs., 3 tabs.

  13. Selection for reduced ferulate esters in seedlings improved maize silage fiber digestibility

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ferulate cross linkage of lignin to arabinoxylans in grasses impedes cell wall digestibility. Formation of cross links requires ferulate esters on arabinoxylan. Subsequent lignin deposition is initiated by formation of cross-linked ferulate/monolignol complexes. We hypothesized that selection for se...

  14. 21 CFR 172.859 - Sucrose fatty acid esters.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sucrose fatty acid esters. 172.859 Section 172.859... CONSUMPTION Multipurpose Additives § 172.859 Sucrose fatty acid esters. Sucrose fatty acid esters identified...) Sucrose fatty acid esters are the mono-, di-, and tri-esters of sucrose with fatty acids and are...

  15. Carboxylic Acid Esters as Substrates of Cholinesterases

    NASA Astrophysics Data System (ADS)

    Brestkin, A. P.; Rozengart, E. V.; Abduvakhabov, A. A.; Sadykov, A. A.

    1983-10-01

    Data on the kinetics of the hydrolysis of various carboxylic acid esters by two main types of cholinesterases — acetylcholinesterase from human erythrocytes and butyrylcholinesterase from horse blood serum — are surveyed. It is shown that the rate of enzyme hydrolysis depends significantly on the structure of the acyl part of the ester molecule, the nature of the ester heteroatom, the structure of the alcohol component, and particularly the structure of the onium group. Esters based on natural products are of special interest as specific substrates of these enzymes. The role of the productive and non-productive sorption of the substrates in enzyme catalysis is demonstrated. The bibliography includes 81 references.

  16. Fumaric acid esters in dermatology

    PubMed Central

    Wollina, Uwe

    2011-01-01

    Fumaric acid esters (FAE) are substances of interest in dermatology. FAE exert various activities on cutaneous cells and cytokine networks. So far only a mixture of dimethylfumarate (DMF) and three salts of monoethylfumarate (MEF) have gained approval for the oral treatment of moderate-to-severe plaque-type psoriasis in Germany. DMF seems to be the major active component. There is evidence that FAE are not only effective and safe in psoriasis but granulomatous non-infectious diseases like granuloma annulare, necrobiosis lipoidica and sarcoidosis. In vitro and animal studies suggest some activity in malignant melanoma as well. PMID:23130241

  17. Steroidal esters from Ferula sinkiangensis.

    PubMed

    Li, Guangzhi; Li, Xiaojin; Cao, Li; Shen, Liangang; Zhu, Jun; Zhang, Jing; Wang, Junchi; Zhang, Lijing; Si, Jianyong

    2014-09-01

    Two new steroidal esters with an unusual framework, Sinkiangenorin A and B, a new organic acid glycoside, Sinkiangenorin C, and four known lignin compounds were isolated from the seeds of Ferula sinkiangensis. The structures of these compounds were established by spectroscopic analysis and single-crystal X-ray diffraction. All of the isolated compounds were tested against Hela, K562 and AGS human cancer cell lines. Sinkiangenorin C showed cytotoxic activity against AGS cells with an IC50 of 36.9 μM. PMID:24979220

  18. Production of wax esters during aerobic growth of marine bacteria on isoprenoid compounds

    PubMed

    Rontani; Bonin; Volkman

    1999-01-01

    This paper describes the production of isoprenoid wax esters during the aerobic degradation of 6,10,14-trimethylpentadecan-2-one and phytol by four bacteria (Acinetobacter sp. strain PHY9, Pseudomonas nautica [IP85/617], Marinobacter sp. strain CAB [DSMZ 11874], and Marinobacter hydrocarbonoclasticus [ATCC 49840]) isolated from the marine environment. Different pathways are proposed to explain the formation of these compounds. In the case of 6,10, 14-trimethylpentadecan-2-one, these esters result from the condensation of some acidic and alcoholic metabolites produced during the biodegradation, while phytol constitutes the alcohol moiety of most of the esters produced during growth on this isoprenoid alcohol. The amount of these esters formed increased considerably in N-limited cultures, in which the ammonium concentration corresponds to conditions often found in marine sediments. This suggests that the bacterial formation of isoprenoid wax esters might be favored in such environments. Although conflicting evidence exists regarding the stability of these esters in sediments, it seems likely that, under some conditions, bacterial esterification can enhance the preservation potential of labile compounds such as phytol. PMID:9872783

  19. Chlorsulfuron modifies biosynthesis of acyl Acid substituents of sucrose esters secreted by tobacco trichomes.

    PubMed

    Kandra, L; Wagner, G J

    1990-11-01

    Sucrose esters and duvatrienediol diterpenes are principal constituents formed in and secreted outside head cells of trichomes occurring on surfaces of Nicotiana tabacum. Using trichome-bearing epidermal peels prepared from midveins of N. tabacum cv T.I. 1068 leaves, we found that chlorsulfuron reduced and modified radiolabeling of sucrose ester acyl acids derived from branched-chain amino acid metabolism. The herbicide did not effect formation and exudation of diterpenes which are products of isoprenoid metabolism. Treatment with 1.0 micromolar chlorsulfuron affected 8.5- and 6.3-fold reductions in radiolabeling of methylvaleryl and methylbutyryl groups of sucrose esters, respectively, and concomitant increases of 9- and 9.8-fold in radiolabeling of straight chain valeryl and butyryl groups, respectively. These results and others indicate that inhibition of acetolactate synthase causes an accumulation of 2-oxo-butyric acid that is utilized by enzymes common to Leu biosynthesis to form 2-oxo-valeric acid. Coenzyme A (CoA) activation of this keto acid gives rise to butyryl CoA, which is utilized to form butyryl containing sucrose esters. Alternatively, reutilization of 2-oxo-valeric acid by the same enzymes followed by CoA activation leads to valeryl containing sucrose esters. We propose that in trichome secretory cells synthase, isomerase and dehydrogenase enzymes which catalyze Leu synthesis/degredation in most tissues, convert iso-branched, anteiso-branched and straight-chain keto acids in the formation of sucrose ester acyl groups. PMID:16667871

  20. Chlorsulfuron Modifies Biosynthesis of Acyl Acid Substituents of Sucrose Esters Secreted by Tobacco Trichomes

    PubMed Central

    Kandra, Lili; Wagner, George J.

    1990-01-01

    Sucrose esters and duvatrienediol diterpenes are principal constituents formed in and secreted outside head cells of trichomes occurring on surfaces of Nicotiana tabacum. Using trichome-bearing epidermal peels prepared from midveins of N. tabacum cv T.I. 1068 leaves, we found that chlorsulfuron reduced and modified radiolabeling of sucrose ester acyl acids derived from branched-chain amino acid metabolism. The herbicide did not effect formation and exudation of diterpenes which are products of isoprenoid metabolism. Treatment with 1.0 micromolar chlorsulfuron affected 8.5- and 6.3-fold reductions in radiolabeling of methylvaleryl and methylbutyryl groups of sucrose esters, respectively, and concomitant increases of 9- and 9.8-fold in radiolabeling of straight chain valeryl and butyryl groups, respectively. These results and others indicate that inhibition of acetolactate synthase causes an accumulation of 2-oxo-butyric acid that is utilized by enzymes common to Leu biosynthesis to form 2-oxo-valeric acid. Coenzyme A (CoA) activation of this keto acid gives rise to butyryl CoA, which is utilized to form butyryl containing sucrose esters. Alternatively, reutilization of 2-oxo-valeric acid by the same enzymes followed by CoA activation leads to valeryl containing sucrose esters. We propose that in trichome secretory cells synthase, isomerase and dehydrogenase enzymes which catalyze Leu synthesis/degredation in most tissues, convert iso-branched, anteiso-branched and straight-chain keto acids in the formation of sucrose ester acyl groups. PMID:16667871

  1. Novel Synthesis of Phytosterol Ester from Soybean Sterol and Acetic Anhydride.

    PubMed

    Yang, Fuming; Oyeyinka, Samson A; Ma, Ying

    2016-07-01

    Phytosterols are important bioactive compounds which have several health benefits including reduction of serum cholesterol and preventing cardiovascular diseases. The most widely used method in the synthesis of its ester analogous form is the use of catalysts and solvents. These methods have been found to present some safety and health concern. In this paper, an alternative method of synthesizing phytosterol ester from soybean sterol and acetic anhydride was investigated. Process parameters such as mole ratio, temperature and time were optimized. The structure and physicochemical properties of phytosterol acetic ester were analyzed. By the use of gas chromatography, the mole ratio of soybean sterol and acetic anhydride needed for optimum esterification rate of 99.4% was 1:1 at 135 °C for 1.5 h. FTIR spectra confirmed the formation of phytosterol ester with strong absorption peaks at 1732 and 1250 cm(-1) , which corresponds to the stretching vibration of C=O and C-O-C, respectively. These peaks could be attributed to the formation of ester links which resulted from the reaction between the hydroxyl group of soybean sterol and the carbonyl group of acetic anhydride. This paper provides a better alternative to the synthesis of phytosterol ester without catalyst and solvent residues, which may have potential application in the food, health-care food, and pharmaceutical industries. PMID:27240315

  2. Liquid chromatographic analysis of a formulated ester from a gas-turbine engine test

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Morales, W.

    1983-01-01

    Size exclusion chromatography (SEC) utilizing mu-Bondagel and mu-Styragel columns with a tetrahydrofuran mobile phase was used to determine the chemical degradation of lubricant samples from a gas-turbine engine test. A MIL-L-27502 candidate, ester-based lubricant was run in a J57-29 engine at a bulk oil temperature of 216 C. In general, the analyses indicated a progressive loss of primary ester, additive depletion, and formation of higher molecular weight material. An oil sample taken at the conclusion of the test showed a reversal of this trend because of large additions of new oil. The high-molecular-weight product from the degraded ester absorbed strongly in the ultraviolet region at 254 nanometers. This would indicate the presence of chromophoric groups. An analysis of a similar ester lubricant from a separate high-temperature bearing test yielded qualitatively similar results.

  3. Fatty esters from vegetable oils for use as a diesel fuel

    SciTech Connect

    Freedman, B.; Pryde, E.H.

    1982-01-01

    Transesterification of sunflower and soybean oils to fatty esters has been carried out to study reaction variables such as: (1) molar ratio of alcohol to vegetable oil, (2) alcohol type (methanol, ethanol, and 1-butanol), (3) catalyst type (alkaline and acidic), and (4) reaction temperature (60/sup 0/, 45/sup 0/, and 32/sup 0/C). These studies showed that ester formation was 90 to 98% complete at the respective molar ratios of methanol/sunflower oil of 4:1 and 6:1. All three alcohols produced high yields of esters. Alkaline catalysts were much more effective than acid catalysts. At both 45/sup 0/ and 60/sup 0/, 97% of methyl esters were produced in 1 hr. 5 figures.

  4. Demethylation kinetics of aspartame and L-phenylalanine methyl ester in aqueous solution.

    PubMed

    Skwierczynski, R D; Connors, K A

    1993-08-01

    The kinetics of demethylation of aspartame and L-phenylalanine methyl ester were studied in aqueous solution at 25 degrees C over the pH range 0.27-11.5. The pseudo-first-order rate constant for aspartame was resolved into individual contributions from methyl ester hydrolysis and diketopiperazine formation. pH-rate profiles were quantitatively described by chemically reasonable kinetic schemes. Aspartame is maximally stable at pH 4 (t90 = 53 days at 25 degrees C); phenylalanine methyl ester, at pH 3. The potentiometrically measured pKa values were pKa1 3.19 and pKa2 7.87 for aspartame and pKa 7.11 for phenylalanine methyl ester. PMID:8415404

  5. Enantiospecific sp2-sp3 coupling of secondary and tertiary boronic esters

    NASA Astrophysics Data System (ADS)

    Bonet, Amadeu; Odachowski, Marcin; Leonori, Daniele; Essafi, Stephanie; Aggarwal, Varinder K.

    2014-07-01

    The cross-coupling of boronic acids and related derivatives with sp2 electrophiles (the Suzuki-Miyaura reaction) is one of the most powerful C-C bond formation reactions in synthesis, with applications that span pharmaceuticals, agrochemicals and high-tech materials. Despite the breadth of its utility, the scope of this Nobel prize-winning reaction is rather limited when applied to aliphatic boronic esters. Primary organoboron reagents work well, but secondary and tertiary boronic esters do not (apart from a few specific and isolated examples). Through an alternative strategy, which does not involve using transition metals, we have discovered that enantioenriched secondary and tertiary boronic esters can be coupled to electron-rich aromatics with essentially complete enantiospecificity. As the enantioenriched boronic esters are easily accessible, this reaction should find considerable application, particularly in the pharmaceutical industry where there is growing awareness of the importance of, and greater clinical success in, creating biomolecules with three-dimensional architectures.

  6. Increased production of wax esters in transgenic tobacco plants by expression of a fatty acid reductase:wax synthase gene fusion.

    PubMed

    Aslan, Selcuk; Hofvander, Per; Dutta, Paresh; Sun, Chuanxin; Sitbon, Folke

    2015-12-01

    Wax esters are hydrophobic lipids consisting of a fatty acid moiety linked to a fatty alcohol with an ester bond. Plant-derived wax esters are today of particular concern for their potential as cost-effective and sustainable sources of lubricants. However, this aspect is hampered by the fact that the level of wax esters in plants generally is too low to allow commercial exploitation. To investigate whether wax ester biosynthesis can be increased in plants using transgenic approaches, we have here exploited a fusion between two bacterial genes together encoding a single wax ester-forming enzyme, and targeted the resulting protein to chloroplasts in stably transformed tobacco (Nicotiana benthamiana) plants. Compared to wild-type controls, transgenic plants showed both in leaves and stems a significant increase in the total level of wax esters, being eight-fold at the whole plant level. The profiles of fatty acid methyl ester and fatty alcohol in wax esters were related, and C16 and C18 molecules constituted predominant forms. Strong transformants displayed certain developmental aberrations, such as stunted growth and chlorotic leaves and stems. These negative effects were associated with an accumulation of fatty alcohols, suggesting that an adequate balance between formation and esterification of fatty alcohols is crucial for a high wax ester production. The results show that wax ester engineering in transgenic plants is feasible, and suggest that higher yields may become achieved in the near future. PMID:26138876

  7. The possible participation of esters as well as amides in prebiotic polymers.

    NASA Technical Reports Server (NTRS)

    Rich, A.

    1971-01-01

    Demonstration that alpha-hydroxy acids may have participated in the formation of prebiological polymers in a manner similar to the participation of alpha-amino acids. Ex periments are described which indicate that the system for forming peptide bonds in present-day biological organisms is equally competent in forming ester and polyester bonds. In particular, the experiments described are directed toward answering questions regarding the action of peptidyl transferase in ester formation. Also, an attempt is made to determine whether a complete protein synthetic system can operate with transfer RNA molecules which have alpha-hydroxyl acids attached to them instead of alpha-amino acids, using both synthetic and natural mRNA. The ability of ribosomal peptidyl transferase to catalyze the formation of an ester bond as well as its normal product, the peptide bond, is demonstrated.

  8. IMPROVED OXIDATIVE STABILITY OF ESTOLIDE ESTERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A wide range of commercial and vegetable-based materials were evaluated for their oxidative stability by the rotating bomb oxidative test (RBOT). RBOT values ranged from 13 to 552 minutes. Two estolides, coconut-oleic estolide 2-ethylhexyl ester and oleic estolide 2-ethylhexyl ester, were evaluate...

  9. Sugar Ester Compounds for Arthropod Control

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugar esters, also known as acyl sugars or polyol esters, are a class of compounds that are internationally recognized as food additives. They are commonly used in bakery goods, drugs, cosmetics, food packaging plastics, and in other applications because of their surfactant and emulsifying properti...

  10. New cycloartenol esters from Ixora coccinea.

    PubMed

    Ragasa, Consolacion Y; Tiu, Floren; Rideout, John A

    2004-08-01

    The air-dried flowers of Ixora coccinea L. afforded two new cycloartenol esters (1a and 1b), lupeol fatty ester, lupeol, ursolic acid, oleanolic acid, and sitosterol. The structures of 1a and 1b were elucidated by extensive 1D and 2D NMR spectroscopy and MS. PMID:15214483

  11. Ethanolysis of rapeseed oil - distribution of ethyl esters, glycerides and glycerol between ester and glycerol phases.

    PubMed

    Cernoch, Michal; Hájek, Martin; Skopal, Frantisek

    2010-04-01

    The distribution of ethyl esters, triglycerides, diglycerides, monoglycerides, and glycerol between the ester and glycerol phase was investigated after the ethanolysis of rapeseed oil at various reaction conditions. The determination of these substances in the ester and glycerol phases was carried out by the GC method. The amount of ethyl esters in the glycerol phase was unexpectedly high and therefore the possibility of the reduction of this amount was investigated. The distribution coefficients and the weight distributions of each investigated substance were calculated and compared mutually. The distribution coefficients between the ester and glycerol phase increase in this sequence: glycerol, monoglycerides, diglycerides, ethyl esters, and triglycerides. Soaps and monoglycerides in the reaction mixture cause a worse separation of ethyl esters from the reaction mixture. The existence of a non-separable reaction mixture was observed also, and its composition was determined. PMID:20005094

  12. Mitochondrial toxicity of phthalate esters.

    PubMed Central

    Melnick, R L; Schiller, C M

    1982-01-01

    The effects of mono- and dibutyl phthalate and mono- and di(2-ethylhexyl) phthalate on energy-dependent K+ uptake, respiration rates, and succinate cytochrome c reductase activities of isolated rat liver mitochondria were evaluated. The energy-coupling processes, active K+ transport and oxidative phosphorylation, were affected most by di-n-butyl phthalate and mono(2-ethylhexyl) phthalate. Mono-n-butyl phthalate had a moderate effect on energy coupling and di(2-ethylhexyl) phthalate had no apparent effect. The potency of inhibition of succinate cytochrome c reductase activity was mono(2-ethylhexyl) phthalate greater than di-n-butyl phthalate greater than mono-n-butyl phthalate = di(2-ethylhexyl) phthalate. It is concluded that phthalate esters affect mitochondrial activities by altering the permeability properties of the inner membrane and by inhibiting succinate dehydrogenase activity. PMID:7140696

  13. Electron-impact ionization of benzoic acid, nicotinic acid and their n-butyl esters

    NASA Astrophysics Data System (ADS)

    Opitz, Joachim

    2007-08-01

    Electron-impact ionization mass spectra, the decay of metastable ions, ionization and appearance energies and bond energies, as dissociation energies, are reported for the title compounds. An ionization energy of 9.47 eV was obtained for benzoic acid, 9.43 eV for benzoic acid n-butyl ester, 9.61 eV for nicotinic acid and 9.97 eV for nicotinic acid n-butyl ester. Molecular ions of both butyl esters show two common main fragmentation pathways: the first process is a McLafferty rearrangement, characterized by the transfer of one H-atom from the aliphatic ester chain, which leads to the ions of either the organic acid or 1-butene. From their appearance energies and known thermodynamic data, gas-phase formation enthalpies () of the parent n-butyl esters are calculated. Values of for benzoic acid n-butyl ester and for nicotinic acid n-butyl ester were obtained. The second process is characterized by the transfer of two H-atoms from the ester chain leading to a protonated form of the corresponding organic acids and C4H7 radicals. Good evidence is provided for the formation of methylallyl radicals. Appearance energies are used to calculate a proton affinity (PA) for benzoic acid. The obtained value of PA = (8.73 ± 0.3) eV, corresponding to a protonation of the carbonyl group, is in close corroboration with published data (PA = 8.51 eV). Activation energies for the intermediate H-transfers were found to be insignificant. This methodic gateway is applied to the system of nicotinic acid and its butyl ester. Adopting the formation of a methylallyl radical, the obtained proton affinity of nicotinic acid, PA = 8.58 eV, is very near to the published data of benzoic acid. An alternative fragmentation mechanism leading to a value of PA [approximate] 9.5 eV (typical for a protonation of the pyridine-nitrogen) is very unlikely. It is concluded that this transfer of two H-atoms from the ester chain is controlled by a charge switching between the carboxylic oxygen atoms which leads to

  14. Polynitroethyl- and fluorodinitroethyl substituted boron esters.

    PubMed

    Klapötke, Thomas M; Krumm, Burkhard; Moll, Richard

    2013-09-01

    The reaction of boron oxide with various nitro-substituted ethanols (2-nitroethanol, 2-fluoro-2,2-dinitroethanol, 2,2,2-trinitroethanol) furnished the corresponding nitroethyl borates B(OCH2CH2NO2)3 (1), B(OCH2CF(NO2)2)3 (2), and B(OCH2C(NO2)3)3 (3). Fluorination of the anion [(NO2)2CCH2OH](-) (4) resulted in 2-fluoro-2,2-dinitroethanol (5), a precursor for 2, and was thoroughly characterized. An interesting condensation was observed with the anion 4 to form the unusual dianion [(NO2)2CCH2C(NO2)2](2-) (6). All compounds were fully characterized by multinuclear NMR spectroscopy, vibrational spectroscopy (IR, Raman), mass spectrometry and elemental analysis. The chemical, physical and energetic properties of 1-3 and 5 are reported, as well as quantum chemical calculations at the CBS-4M level of theory to predict the enthalpies and energies of formation. X-ray diffraction studies were performed, and the crystal structures for compounds 1-6 were determined and discussed thoroughly. The boron esters 1-3 are of interest as possible candidates for smoke-free, green colorants in pyrotechnic applications, and in case of 2 and 3 also as promising high energy oxidizers. PMID:23893716

  15. Pure, transparent-melting starch esters: synthesis and characterization.

    PubMed

    Liebert, Tim; Nagel, Matilde C V; Jordan, Torsten; Heft, Andreas; Grünler, Bernd; Heinze, Thomas

    2011-09-01

    Long chain starch esters were prepared by a new method using molten imidazole as solvent for the biopolymer. The advantage is the simplicity of the reaction mixture. Imidazole is acting not only as solvent, but also as reagent and base. The reaction succeeds via the imidazolide, which is formed in situ with an acid chloride. It yields highly pure derivatives, as could be shown by NMR spectroscopy and elemental analysis. No hints for desoxychloro substituents or other impurities could be found. The high quality of the products prepared is responsible for the occurrence of colorless melts. Although DSC measurements show a variety of thermal transitions, the formation of melts in the range of 40 to 255 °C could be observed with a hot stage microscope. The melting behavior can be adjusted by the type of ester moiety and the amount of ester functions introduced. In case of starch palmitates completely transparent melts are obtained within two distinct DS regions namely around 1.5 and 2.2 to 3.0. Upon cooling the melts form homogeneous films on different supports including glass. They show good adhesion and should therefore be a suitable basic material for the preparation of composites like laminated glass. PMID:21823185

  16. Lipase-catalyzed (trans)esterification of 5-hydroxy- methylfurfural and separation from HMF esters using deep-eutectic solvents.

    PubMed

    Krystof, Monika; Pérez-Sánchez, María; Domínguez de María, Pablo

    2013-04-01

    5-Hydroxymethylfurfural (HMF) is a valuable biomass-derived building block. Among possible HMF valorization products, a broad range of HMF esters can be synthesized. These HMF esters have found some promising applications, such as monomers, fuels, additives, surfactants, and fungicides, and thus several catalytic approaches for HMF (trans)esterifications have been reported. The intrinsic reactivity of HMF is challenging, forcing the use of mild reaction conditions to avoid by-product formation. This paper explores the lipase-catalyzed (trans)esterification of HMF with different acyl donors (carboxylic acids and methyl- and ethyl esters) mostly in solvent-free conditions. The results demonstrate that lipases may be promising alternatives for the synthesis of HMF esters-with high productivities and reactions at high substrate loadings-provided that robust systems for lipase immobilization are applied to assure an adequate reusability of the enzymes. Once (trans)esterifications have been conducted, the separation of unreacted HMF and HMF esters is performed by using deep-eutectic solvents (DES) as separation agents. DES are able to dissolve hydrogen-bond donors (e.g., HMF), whereas non-hydrogen-bond donors (in this case HMF esters) form a second phase. By using this approach, high ester purities (>99 %) and efficiencies (up to >90 % HMF ester recovery) in separations were obtained by using choline chloride-based DES. PMID:23456887

  17. Synthesis and characterization of ester and amide derivatives of titanium(IV) carboxymethylphosphonate

    SciTech Connect

    Melánová, Klára; Beneš, Ludvík; Trchová, Miroslava; Svoboda, Jan; Zima, Vítězslav

    2013-06-15

    A set of layered ester and amide derivatives of titanium(IV) carboxymethylphosphonate was prepared by solvothermal treatment of amorphous titanium(IV) carboxymethylphosphonate with corresponding 1-alkanols, 1,ω-alkanediols, 1-aminoalkanes, 1,ω-diaminoalkanes and 1,ω-amino alcohols and characterized by powder X-ray diffraction, IR spectroscopy and thermogravimetric analysis. Whereas alkyl chains with one functional group form bilayers tilted to the layers, 1,ω-diaminoalkanes and most of 1,ω-alkanediols form bridges connecting the adjacent layers. In the case of amino alcohols, the alkyl chains form bilayer and either hydroxyl or amino group is used for bonding. This simple method for the synthesis of ester and amide derivatives does not require preparation of acid chloride derivative as a precursor or pre-intercalation with alkylamines and can be used also for the preparation of ester and amide derivatives of titanium carboxyethylphosphonate and zirconium carboxymethylphosphonate. - Graphical abstract: Ester and amide derivatives of layered titanium carboxymethylphosphonate were prepared by solvothermal treatment of amorphous solid with alkanol or alkylamine. - Highlights: • Ester and amide derivatives of titanium carboxymethylphosphonate. • Solvothermal treatment of amorphous solid with alkanol or alkylamine. • Ester and amide formation confirmed by IR spectroscopy.

  18. Oleoyl and linoleoyl esters of fumonisin B1 are differently produced by Fusarium verticillioides on maize and rice based media.

    PubMed

    Falavigna, C; Lazzaro, I; Galaverna, G; Dall'Asta, C; Battilani, P

    2016-01-18

    Fatty acid esters of fumonisins, namely oleoyl- and linoleoyl esters of fumonisin B1 (EFB1OA and EFB1LA, respectively), are modified forms of fumonisins whose formation and occurrence have been reported so far in naturally infected maize and in artificially inoculated rice. There is a lack of knowledge about the mechanism of formation, mainly in relation to the role played by the substrate. Therefore, in this work we studied the dynamics of accumulation of the toxin and its esters, together with their precursor, in maize and rice based media inoculated with different strains of F. verticillioides and incubated at 25 °C for 7-45 days. The production pattern of FB1 and its modified forms was significantly influenced by growth media, reaching a higher concentration in cornmeal compared to rice based medium. Similarly, cornmeal was more supportive for the conversion of FB1 by considering the esterification rate, with a prevalence of linoleoyl esters compared to oleoyl esters resembling the OA/LA rate in both media. The conversion of FB1 into fatty acid esters was also shown as strain-related. Results, thus, strongly support the hypothesis that fatty acid esters of FB1 are produced by the fungus itself at a late stage of growth, or at a certain point of FB1 accumulation in the medium, using fatty acids from the substrate. PMID:26492388

  19. Fatty acid esters of monochloropropanediol (MCPD) and glycidol in refined edible oils.

    PubMed

    Craft, B D; Chiodini, A; Garst, J; Granvogl, M

    2013-01-01

    Recently, fatty acid esters of monochloropropanediol (MCPD) and that of glycidol have been reported in refined edible oils. Since then a wealth of research has been published on the factors influencing the formation of these contaminants in foods. It can be noted that the predominant precursors in a given matrix will not necessarily be the same as in other matrices. Further, proven relationships in the past between precursors responsible for free MCPD or free glycidol formation will not necessarily be valid for their fatty acid-esterified counterparts. This review attempts to summarise the current status of the literature as it pertains to the reasons surrounding the manifestation of MCPD esters and glycidyl esters in oils and fats. Recent efforts to mitigate the levels of these contaminants were highlighted and put into the context of their respective reaction matrices. As more accurate occurrence data for MCPD esters and glycidyl esters in other foods are collected, more targeted mitigation experiments can be formulated with respect to the reaction matrices under investigation. PMID:23020600

  20. Thermal Decomposition of Methyl Esters in Biodiesel Fuel: Kinetics, Mechanisms and Products

    NASA Astrophysics Data System (ADS)

    Chai, Ming

    Biodiesel continues to enjoy increasing popularity. However, recent studies on carbonyl compounds emissions from biodiesel fuel are inconclusive. Emissions of carbonyl compounds from petroleum diesel fuels were compared to emissions from pure biodiesel fuels and petroleum-biodiesel blends used in a non-road diesel generator. The concentration of total carbonyl compounds was the highest when the engine was idling. The carbonyl emissions, as well as ozone formation potential, from biodiesel fuel blends were higher than those emitted from petroleum diesel fuel. The sulfur content of diesel fuel and the source of biodiesel fuel were not found to have a significant impact on emissions of carbonyl compounds. Mechanism parameters of the thermal decomposition of biodiesel-range methyl esters were obtained from the results of thermal gravimetric analysis (TGA). The overall reaction orders are between 0.49 and 0.71 and the energies of activation are between 59.9 and 101.3 kJ/mole. Methyl esters in air have lower activation energies than those in nitrogen. Methyl linoleate has the lowest activation energy, followed by methyl oleate, and methyl stearate. The pyrolysis and oxidation of the three methyl esters were investigated using a semi-isothermal tubular flow reactor. The profiles of major products versus reaction temperature are presented. In the pyrolysis of methyl stearate, the primary reaction pathway is the decarboxylic reaction at the methyl ester functional group. Methyl oleate's products indicate more reactions on its carbon-carbon double bond. Methyl linoleate shows highest reactivity among the three methyl esters, and 87 products were detected. The oxidation of three methyl esters resulted in more products in all compound classes, and 55, 114, and 127 products were detected, respectively. The oxidation of methyl esters includes decarboxylation on ester group. The methyl ester's carbon chain could be oxidized as a hydrocarbon compound and form oxidized esters and

  1. Thermal Decomposition of Ethyl Formate behind the Reflected Shock Waves in the Temperature Range of 909-1258K

    NASA Astrophysics Data System (ADS)

    Balaganesh, M.; Sudhakar, G.; Rajakumar, B.

    Ethyl formate is the simplest model of ethyl esters which are considered as biodiesel. Systematic tests on properties and reactivity of biodiesel have been reported[1, 2]. Methyl and ethyl ester mix can offer improved physical properties. Generally, ethyl esters are slightly more reactive than the methyl esters[3]. Also ethyl formate is an interstellar molecule. It was first detected in interstellar space by Belloche et al.[4]. So studies of this molecule are required to understand the fuel properties and interstellar chemistry.

  2. Radiolabeled cholesteryl ethers trace LDL cholesteryl esters but not HDL cholesteryl esters in the rat.

    PubMed

    Terpstra, A H

    1995-01-01

    The intravascular metabolism of cholesteryl [1-14C]oleoyl ester and [1,2-3H(N)]cholesteryl palmityl ether was compared in the rat, an animal species without plasma cholesteryl ester transfer activity (CETA). The tracers had identical plasma disappearance rates when they were incorporated into human or rat low density lipoproteins (LDL). Fractional catabolic rates (FCR) were 0.081 +/- 0.014 h-1 and 0.080 +/- 0.013 h-1 for human LDL ester and ether and 0.098 +/- 0.007 h-1 and 0.101 +/- 0.007 h-1 for rat LDL ester and ether, respectively. In contrast, the ether had plasma disappearance rates that were 24%-25% lower than the ester when they were incorporated into human or rat high density lipoproteins (HDL). FCR were 0.230 +/- 0.020 and 0.173 +/- 0.030 h-1 for human HDL ester and ether and 0.131 +/- 0.020 h-1 and 0.100 +/- 0.017 h-1 for rat HDL ester and ether respectively. Biological screening of the rat HDL preparations did not affect these differences. The results of these studies indicate that in the absence of plasma CETA, cholesteryl ethers can be used to trace LDL cholesteryl esters but not to trace HDL cholesteryl esters. PMID:7772060

  3. 5-formylfurfuryl esters from Duabanga grandiflora.

    PubMed

    Kaweetripob, Wirongrong; Mahidol, Chulabhorn; Prachyawarakorn, Vilailak; Prawat, Hunsa; Ruchirawat, Somsak

    2012-04-01

    5-Formylfurfuryl esters, duabanganals A-D, together with sixteen known compounds, a known 5-formylfurfuryl ester, latifolinal, eight pentacyclic triterpenes, a benzofuran derivative, an ellagic acid derivative, vanillin, β-sitosterol, β-sitosterol glucoside, 3-hydroxy-4-methoxycinnamaldehyde, and 5-formylfurfurol, were isolated from the stem bark of Duabanga grandiflora. The structures of these compounds were elucidated on the basis of spectroscopic analysis. Several of these metabolites were evaluated for cytotoxic activities against six cancer cell lines. PMID:22317905

  4. Synthesis of a new energetic nitrate ester

    SciTech Connect

    Chavez, David E

    2008-01-01

    Nitrate esters have been known as useful energetic materials since the discovery of nitroglycerin by Ascanio Sobrero in 1846. The development of methods to increase the safety and utility of nitroglycerin by Alfred Nobel led to the revolutionary improvement in the utility of nitroglycerin in explosive applications in the form of dynamite. Since then, many nitrate esters have been prepared and incorporated into military applications such as double-based propellants, detonators and as energetic plasticizers. Nitrate esters have also been shown to have vasodilatory effects in humans and thus have been studied and used for treatments of ailments such as angina. The mechanism of the biological response towards nitrate esters has been elucidated recently. Interestingly, many of the nitrate esters used for military purposes are liquids (ethylene glycol dinitrate, propylene glycol dinitrate, etc). Pentaerythritol tetranitrate (PETN) is one of the only solid nitrate esters, besides nitrocellulose, that is used in any application. Unfortunately, PETN melting point is above 100 {sup o}C, and thus must be pressed as a solid for detonator applications. A more practical material would be a melt-castable explosive, for potential simplification of manufacturing processes. Herein we describe the synthesis of a new energetic nitrate ester (1) that is a solid at ambient temperatures, has a melting point of 85-86 {sup o}C and has the highest density of any known nitrate ester composed only of carbon, hydrogen, nitrogen and oxygen. We also describe the chemical, thermal and sensitivity properties of 1 as well as some preliminary explosive performance data.

  5. Investigation of the extraction properties of dibutyl ester of dibutoxymethane phosphonic acid

    SciTech Connect

    Herrmann, E.; Hala, J.

    1983-01-01

    The extraction properties of the dibutyl ester of dibutoxymethane phosphonic acid (DBDBMP), an analog of TBP with a P-C bond, were shown to be similar to those of TBP except for hydrolysis of DBDBMP in acidic solutions. The formation of acidic organophosphorus compounds during hydrolysis of DBDBMP was confirmed by /sup 31/P-N.M.R. measurements. 4 figures, 1 table.

  6. INDIUM MEDIATED REACTIONS IN WATER: SYNTHESIS OF BETA-HYDROXYL ESTERS. (R822668)

    EPA Science Inventory

    Abstract

    A variety of small beta, Greek-hydroxyl esters were synthesized efficiently through indium mediated carbon-carbon bond formation in water followed by ozonolysis.

  7. Parkin-catalyzed Ubiquitin-Ester Transfer Is Triggered by PINK1-dependent Phosphorylation*

    PubMed Central

    Iguchi, Masahiro; Kujuro, Yuki; Okatsu, Kei; Koyano, Fumika; Kosako, Hidetaka; Kimura, Mayumi; Suzuki, Norihiro; Uchiyama, Shinichiro; Tanaka, Keiji; Matsuda, Noriyuki

    2013-01-01

    PINK1 and PARKIN are causal genes for autosomal recessive familial Parkinsonism. PINK1 is a mitochondrial Ser/Thr kinase, whereas Parkin functions as an E3 ubiquitin ligase. Under steady-state conditions, Parkin localizes to the cytoplasm where its E3 activity is repressed. A decrease in mitochondrial membrane potential triggers Parkin E3 activity and recruits it to depolarized mitochondria for ubiquitylation of mitochondrial substrates. The molecular basis for how the E3 activity of Parkin is re-established by mitochondrial damage has yet to be determined. Here we provide in vitro biochemical evidence for ubiquitin-thioester formation on Cys-431 of recombinant Parkin. We also report that Parkin forms a ubiquitin-ester following a decrease in mitochondrial membrane potential in cells, and that this event is essential for substrate ubiquitylation. Importantly, the Parkin RING2 domain acts as a transthiolation or acyl-transferring domain rather than an E2-recruiting domain. Furthermore, formation of the ubiquitin-ester depends on PINK1 phosphorylation of Parkin Ser-65. A phosphorylation-deficient mutation completely inhibited formation of the Parkin ubiquitin-ester intermediate, whereas phosphorylation mimics, such as Ser to Glu substitution, enabled partial formation of the intermediate irrespective of Ser-65 phosphorylation. We propose that PINK1-dependent phosphorylation of Parkin leads to the ubiquitin-ester transfer reaction of the RING2 domain, and that this is an essential step in Parkin activation. PMID:23754282

  8. Allied, MGC link on cyanate esters

    SciTech Connect

    Wood, A.

    1993-02-24

    In the latest of a line of joint ventures in its plastics business, Allied Signal has reached agreement with Mitsubishi Gas Chemical (MGC) to jointly develop thermoset cyanate ester resins and blends. The deal will involve further development of Allied Signal's Primaset phenol-formaldehyde cyanate ester resins, a new entrant in the thermoset arena. Although the Primaset resins were discovered in the 1960s, this would be the first time they are available commercially. The deal will marry Primaset technology with MGC's Skylex bisphenol A cyanate ester resins, says Fred DiAntonis, director/advanced materials at Allied Signal. The two firms are looking at marketing blends of the two materials. The potential market for these resins, used commercially by the electronics industry in printed circuit boards and by the aerospace industry in composites, is significant, says Robert P. Viarengo, Allied Signal president/performance materials. By aligning ourselves with MGC, the world leader in cyanate ester resin, we anticipate moving forward aggressively. The main competitor is Ciba, which acquired bisphenol A cyanate ester resins with its purchase of Rhone-Poulenc's high temperature resins business. DiAntonis estimates the market for cyanate ester resins could be worth $150 million by the end of the decade, although development costs have been in the tens of millions of dollars range.

  9. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2-ethylhexanol, benzyl alcohol, in the presence of Bronsted acid catalyst, were investigated. Products that were not reported in prior studies of similar reactions were found. These were furan fatty acid a...

  10. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Epoxidation of vegetable oils and consecutive epoxide ring-opening reaction is a widely investigated path for producing biobased lubricants and polymers. The reaction mechanism and products are considered well-studied and known. In the current study, the reactions of epoxidized alkyl soyate with fou...

  11. Formation of furan fatty alkyl esters from their bis-epoxide fatty esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2-ethylhexanol, and benzyl alcohol were investigated in the presence of Bronsted acid catalyst. Products not reported in prior studies of similar reactions were found. These were furan fatty acid alkyl est...

  12. Thio Wax Ester Biosynthesis Utilizing the Unspecific Bifunctional Wax Ester Synthase/Acyl Coenzyme A:Diacylglycerol Acyltransferase of Acinetobacter sp. Strain ADP1

    PubMed Central

    Uthoff, Stefan; Stöveken, Tim; Weber, Nikolaus; Vosmann, Klaus; Klein, Erika; Kalscheuer, Rainer; Steinbüchel, Alexander

    2005-01-01

    The bifunctional wax ester synthase/acyl coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT) from Acinetobacter sp. strain ADP1 (formerly Acinetobacter calcoaceticus ADP1) mediating the biosyntheses of wax esters and triacylglycerols was used for the in vivo and in vitro biosynthesis of thio wax esters and dithio wax esters. For in vitro biosynthesis, 5′His6WS/DGAT comprising an N-terminal His6 tag was purified from the soluble protein fraction of Escherichia coli Rosetta(DE3)pLysS (pET23a::5′His6atf). By employing SP-Sepharose high-pressure and Ni-nitrilotriacetic acid fast-protein liquid chromatographies, a 19-fold enrichment with a final specific activity of 165.2 nmol mg of protein−1 min−1 was achieved by using 1-hexadecanol and palmitoyl-CoA as substrates. Incubation of purified 5′His6WS/DGAT with 1-hexadecanethiol and palmitoyl-CoA as substrates resulted in the formation of palmitic acid hexadecyl thio ester (10.4% relative specific activity of a 1-hexadecanol control). Utilization of 1,8-octanedithiol and palmitoyl-CoA as substrates led to the formation of 1-S-monopalmitoyloctanedithiol and minor amounts of 1,8-S-dipalmitoyloctanedithiol (59.3% relative specific activity of a 1-hexadecanol control). The latter dithio wax ester was efficiently produced when 1-S-monopalmitoyloctanedithiol and palmitoyl-CoA were used as substrates (13.4% specific activity relative to that of a 1-hexadecanol control). For the in vivo biosynthesis of thio wax esters, the knockout mutant Acinetobacter sp. strain ADP1acr1ΩKm, which is unable to produce fatty alcohols, was used. Cultivation of Acinetobacter sp. strain ADP1acr1ΩKm in the presence of gluconate, 1-hexadecanethiol, and oleic acid in nitrogen-limited mineral salts medium resulted in the accumulation of unusual thio wax esters that accounted for around 1.19% (wt/wt) of the cellular dry weight and consisted mainly of oleic acid hexadecyl thioester as revealed by gas chromatography-mass spectrometry

  13. Photocatalyzed multiple additions of amines to {alpha}, {beta}-unsaturated esters and nitriles

    SciTech Connect

    Das, S.; Kumar, J.S.D.; Thomas, K.G.; Shivaramayya, K.; George, M.V. |

    1994-02-11

    Photoelectron-transfer-catalyzed intermolecular carbon-carbon bond formation of primary, secondary, and tertiary amines with {alpha}, {beta}-unsaturated esters and nitriles using photosensitizers such as anthraquinone, acridone, and dicyanoanthracene has been investigated. The addition of {alpha}-aminoalkyl radicals, generated via photoelectron-transfer processes, to olefinic substrates and the subsequent 1,5-hydrogen abstraction reactions of the amine-olefin adduct radicals lead to a number of interesting multiple-olefin-added products. The adducts of the primary and secondary amines with {alpha}, {beta}-unsaturated esters undergo further cyclizations to give spiro and cyclic lactams, respectively.

  14. Methyl esters from vegetable oils with hydroxy fatty acids: Comparison of lesquerella and castor methyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The search for alternative feedstocks for biodiesel as partial replacement for petrodiesel has recently extended to castor oil. In this work, the castor oil methyl esters were prepared and their properties determined in comparison to the methyl esters of lesquerella oil, which in turn is seen as alt...

  15. Detection of testosterone esters in blood.

    PubMed

    Forsdahl, Guro; Erceg, Damir; Geisendorfer, Thomas; Turkalj, Mirjana; Plavec, Davor; Thevis, Mario; Tretzel, Laura; Gmeiner, Günter

    2015-01-01

    Injections of synthetic esters of testosterone are among the most common forms of testosterone application. In doping control, the detection of an intact ester of testosterone in blood gives unequivocal proof of the administration of exogenous testosterone. The aim of the current project was to investigate the detection window for injected testosterone esters as a mixed substance preparation and as a single substance preparation in serum and plasma. Furthermore, the suitability of different types of blood collection devices was evaluated. Collection tubes with stabilizing additives, as well as non-stabilized serum separation tubes, were tested. A clinical study with six participants was carried out, comprising a single intramuscular injection of either 1000 mg testosterone undecanoate (Nebido(®)) or a mixture of 30 mg testosterone propionate, 60 mg testosterone phenylpropionate, 60 mg testosterone isocaproate, and 100 mg testosterone decanoate (Sustanon(®)). Blood was collected throughout a testing period of 60 days. The applied analytical method for blood analysis included liquid-liquid extraction and preparation of oxime derivatives, prior to TLX-sample clean-up and liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. All investigated testosterone esters could be detected in post-administration blood samples. The detection time depended on the type of ester administered. Furthermore, results from the study show that measured blood concentrations of especially short-chained testosterone esters are influenced by the type of blood collection device applied. The testosterone ester detection window, however, was comparable. PMID:26695486

  16. The Benzyl Ester Group of Amino Acid Monomers Enhances Substrate Affinity and Broadens the Substrate Specificity of the Enzyme Catalyst in Chemoenzymatic Copolymerization.

    PubMed

    Ageitos, Jose Manuel; Yazawa, Kenjiro; Tateishi, Ayaka; Tsuchiya, Kousuke; Numata, Keiji

    2016-01-11

    The chemoenzymatic polymerization of amino acid monomers by proteases involves a two-step reaction: the formation of a covalent acyl-intermediate complex between the protease and the carboxyl ester group of the monomer and the subsequent deacylation of the complex by aminolysis to form a peptide bond. Although the initiation with the ester group of the monomer is an important step, the influence of the ester group on the polymerization has not been studied in detail. Herein, we studied the effect of the ester groups (methyl, ethyl, benzyl, and tert-butyl esters) of alanine and glycine on the synthesis of peptides using papain as the catalyst. Alanine and glycine were selected as monomers because of their substantially different affinities toward papain. The efficiency of the polymerization of alanine and glycine benzyl esters was much greater than that of the other esters. The benzyl ester group therefore allowed papain to equally polymerize alanine and glycine, even though the affinity of alanine toward papain is substantially higher. The characterization of the copolymers of alanine and glycine in terms of the secondary structure and thermal properties revealed that the thermal stability of the peptides depends on the amino acid composition and resultant secondary structure. The current results indicate that the nature of the ester group drastically affects the polymerization efficiency and broadens the substrate specificity of the protease. PMID:26620763

  17. Heating Two Types of Enriched Margarine: Complementary Analysis of Phytosteryl/Phytostanyl Fatty Acid Esters and Phytosterol/Phytostanol Oxidation Products.

    PubMed

    Scholz, Birgit; Menzel, Nicole; Lander, Vera; Engel, Karl-Heinz

    2016-04-01

    Two phytosteryl and/or phytostanyl fatty acid ester-enriched margarines were subjected to common heating procedures. UHPLC-APCI-MS analysis resulted for the first time in comprehensive quantitative data on the decreases of individual phytosteryl/-stanyl fatty acid esters upon heating of enriched foods. These data were complemented by determining the concurrently formed phytosterol/-stanol oxidation products (POPs) via online LC-GC. Microwave-heating led to the least decreases of esters of approximately 5% in both margarines. Oven-heating of the margarine in a casserole caused the greatest decreases, with 68 and 86% esters remaining, respectively; the impact on individual esters was more pronounced with increasing degree of unsaturation of the esterified fatty acids. In the phytosteryl/-stanyl ester-enriched margarine, approximately 20% of the ester losses could be explained by the formation of POPs; in the phytostanyl ester-enriched margarine, the POPs accounted for <1% of the observed ester decreases. PMID:26996218

  18. Assays for the classification of two types of esterases: carboxylic ester hydrolases and phosphoric triester hydrolases.

    PubMed

    Anspaugh, Douglas D; Roe, R Michael

    2002-11-01

    Assays for the Classification of Two Types of Esterases: Carboxylic Ester Hydrolase and Phosphoric Triester Hydrolase (Douglas D. Anspaugh and Michael Roe, North Carolina State University, Raleigh, North Carolina). This unit describes assays that quantitate two types of esterase the carboxylic ester hydrolases and the phosphoric triester hydrolases. Carboxylic ester hydrolases include the B-esterases, which are inhibited by organophosphorus compounds. Among the phosphoric triester hydrolases is aryldialkylphosphatase, which has been called A-esterase or paraoxonase due to its ability to oxidize paraoxon and other organophosphates. These assays are colorimetric and miniaturized for rapid simultaneous testing of multiple, small-volume samples in a microtiter plate format. There is also a discussion of the history of esterase nomenclature and the reasons why this large group of enzymes is so difficult to classify. PMID:20945297

  19. Papain-Catalyzed Chemoenzymatic Synthesis of Telechelic Polypeptides Using Bis(Leucine Ethyl Ester) Initiator.

    PubMed

    Tsuchiya, Kousuke; Numata, Keiji

    2016-07-01

    In order to construct unique polypeptide architectures, a novel telechelic-type initiator with two leucine ethyl ester units is designed for chemoenzymatic polymerization. Glycine or alanine ethyl ester is chemoenzymatically polymerized using papain in the presence of the initiator, and the propagation occurs at each leucine ethyl ester unit to produce the telechelic polypeptide. The formation of the telechelic polypeptides is confirmed by (1) H NMR and MALDI-TOF mass spectroscopies. It is revealed by AFM observation that long nanofibrils are formed from the telechelic polyalanine, whereas a conventional linear polyalanine with a similar degree of polymerization shows granule-like structures. The telechelic polyglycine and polyalanine show the crystalline structures of Polyglycine II and antiparallel β-sheet, respectively. It is demonstrated that this method to synthesize telechelic-type polypeptides potentially opens up a pathway to construct novel hierarchical structures by self-assembly. PMID:26947148

  20. Synthesis of Chiral Tertiary Boronic Esters by Oxime-Directed Catalytic Asymmetric Hydroboration.

    PubMed

    Shoba, Veronika M; Thacker, Nathan C; Bochat, Andrew J; Takacs, James M

    2016-01-22

    Chiral boronic esters are useful intermediates in asymmetric synthesis. We have previously shown that carbonyl-directed catalytic asymmetric hydroboration (CAHB) is an efficient approach to the synthesis of functionalized primary and secondary chiral boronic esters. We now report that the oxime-directed CAHB of alkyl-substituted methylidene and trisubstituted alkene substrates by pinacolborane (pinBH) affords oxime-containing chiral tertiary boronic esters with yields up to 87% and enantiomeric ratios up to 96:4 e.r. The utility of the method is demonstrated by the formation of chiral diols and O-substituted hydroxylamines, the generation of quaternary carbon stereocenters through carbon-carbon coupling reactions, and the preparation of chiral 3,4,4-trisubstituted isoxazolines. PMID:26662460

  1. Tautomerism and stereodynamics of acyclic. beta. -diketo esters

    SciTech Connect

    Romas, A.D.; Esakov, S.M.; Petrov, Al.An.; Ershov, B.A.

    1986-04-10

    The tautomeric transformations and stereodynamics of a series of ring-substituted acyclic ..beta..-diketo esters p-XC/sub 6/H/sub 4/COCH(CH/sub 3/CO)CO/sub 2/CH/sub 3/ in hexachlorobutadiene and nitrobenzene were investigated by proton and carbon magnetic resonance spectroscopy. The enolization of the compounds is accompanied by the formation of two cis-enol forms (of the three theoretically possible forms) with nonchelated benzene of methoxycarbonyl groups respectively. The form with the nonchelated methoxycarbonyl group predominates in the equilibrium on account of the smaller loss of entropy during its formation compared with the enol containing the nonchelated benzoyl group. The kinetic characteristics of the mutual transformations of the enolic forms in hexachlorobutadiene and nitrobenzene respectively were determined by integration and dynamic nuclear magnetic resonance.

  2. Synthesis of bioreductive esters from fungal compounds.

    PubMed

    Weerapreeyakul, Natthida; Anorach, Rutchayaporn; Khuansawad, Thidarut; Yenjai, Chavi; Isaka, Masahiko

    2007-06-01

    Four new bioreductive esters (7-10) have been synthesized. Their structures composed of trimethyl lock containing quinone propionic acid with an ester linkage to the fungal cytotoxic compounds; preussomerin G (1), preussomerin I (2), phaseolinone (3) and phomenone (4). The synthesized esters are aimed to act via reductive activation specifically at the cancer cells, resulting from hypoxia and overexpression of reductases. Hence, the toxicity will be lessened during distribution across the normal cells. The anticancer activity was determined in cancer cell lines with reported reductase i.e., BC-1 cells and NCI-H187 as well as in non-reductase containing cancer cells; KB cells. When considering each cell lines, result showed that structure modification giving to 7-10 led to less cytotoxicity than their parent compounds (1-4). Both 7 and 8 were strongly cytotoxic (IC50 < or = 5 microg/ml) to NCI-H187, whereas 9 and 10 were moderately cytotoxic (IC50 = 6-10 microg/ml) to BC-1 cells. Additional study of stability of represented phenolic ester (8) and an alcoholic ester (9) were performed. Result illustrated that both 8 and 9 were stable in the presence of esterase. Therefore, the cytotoxicity of the synthesized compounds (8-10) might be due to partial bioreductive activation in the cancer cells. PMID:17541198

  3. Anaerobic degradation kinetics of a cholesteryl ester.

    PubMed

    Gutiérrez, S; Viñas, M

    2003-01-01

    The most important components of wool scouring effluent grease are esters of sterols. Cholesteryl palmitate (CP) is the main ester in this grease. In this paper, the influence of the ester concentration in the anaerobic digestion and the relative rate of the different degradation steps, are studied. The experiment was carried out to measure methane production in the anaerobic degradation of acetate, palmitic acid (PA) and CP. A first-order kinetic model was assumed for hydrolysis and Monod models were assumed for both the methanogenic and acetogenic steps. Maximum hydrolysis rate was found to be around 20 times faster than the maximum methanogenic reaction rate during the experience. The lanolin emulsion drop size effect was also evaluated employing fine and coarse stock lanolin emulsions and no adapted sludge. Concentrations of 13.7 to 4.6 gCOD x l(-1) were employed. In a previous study, the effect of palmitic acid emulsion size was found important when similar sludge was tested. When esters are degraded, a significant effect of drop size on the degradation rate was not found. The difference between CP and PA emulsions behavior could be due to the fact that cholesterol produced during the ester degradation has a protective effect on the sludge. PMID:14640211

  4. Structural Control of Bisurea-Based Supramolecular Polymers: Influence of an Ester Moiety.

    PubMed

    Dirany, Mohammed; Ayzac, Virgile; Isare, Benjamin; Raynal, Matthieu; Bouteiller, Laurent

    2015-10-27

    A few examples of monomers are known that self-assemble into various high molar mass structures in solution. Controlling the morphology of the resulting supramolecular polymers is a highly desirable goal for many applications. Herein, we compare the self-assembling properties of newly prepared ester bisurea monomers with those of previously investigated alkyl bisurea monomers. The ester functionality decreases the hydrogen bonding strength of the bisurea monomers but does not prevent the formation of long assemblies in nonpolar solvents: gels are formed at millimolar concentration. Surprisingly, ester bisureas self-assemble at room temperature into rod-like urea-bonded supramolecular polymers that are different from the ones formed by alkyl bisureas. The rods formed by ester bisurea supramolecular polymers are compact (instead of tubular in the case of alkyl bisureas) and display two monomers in the cross-section (instead of three in the case of alkyl bisureas). The stability of the structures formed by ester bisureas can be easily tuned by changing the nature of the substituent in the α-position of the urea functions and/or the nature of the alkyl side chains. PMID:26461519

  5. Synthesis of functionalized poly(ester carbonate) with laminin-derived peptide for promoting neurite outgrowth of PC12 cells.

    PubMed

    Xing, Dongming; Ma, Lie; Gao, Changyou

    2014-10-01

    Maleimide-functionalized poly(ester carbonate)s are synthesized by ring-opening copolymerization of furan-maleimide functionalized trimethylene carbonate (FMTMC) with L-lactide and a subsequent retro Diels-Alder reaction. The maleimide groups on poly(ester carbonate)s are amenable to Michael addition with thiol-containing molecules such as 3-mercapto-1-propanol, 2-aminoethanethiol hydrochloride, and mercaptoacetic acid under mild conditions, enabling the formation of biodegradable materials with various functional groups (e.g., hydroxyl, amine, and carboxyl). In particular, the maleimide-functionalized poly(ester carbonate) is clicked with a laminin-derived peptide CQAASIKVAV. In vitro culture of PC12 cells shows that the maleimide-functionalized polymers, especially the CQAASIKVAV-grafted one, could support cell proliferation and neurite outgrowth. The maleimide-functionalized poly(ester carbonate)s provide a versatile platform for diverse functionalization and have comprehensive potential in biomedical engineering. PMID:24962245

  6. Cleavable ester-linked magnetic nanoparticles for labeling of solvent-exposed primary amine groups of peptides/proteins.

    PubMed

    Patil, Ujwal S; Osorno, Laura; Ellender, Angela; Grimm, Casey; Tarr, Matthew A

    2015-09-01

    To study the solvent-exposed lysine residues of peptides/proteins, we previously reported disulfide-linked N-hydroxysuccinimide ester-modified silica-coated iron oxide magnetic nanoparticles (NHS-SS-SiO2@Fe3O4 MNPs). The presence of a disulfide bond in the linker limits the use of disulfide reducing agent during protein digestion and allows unwanted disulfide formation between the MNPs and protein. In the current work, the disulfide bond was replaced with a cleavable ester group to synthesize NHS ester-modified SiO2@Fe3O4 MNPs. Use of the cleavable ester group provides an improved method for protein labeling and allows the use of disulfide reducing agents during protein digestion. PMID:25983234

  7. Phthalate esters as peroxisome proliferator carcinogens.

    PubMed Central

    Warren, J R; Lalwani, N D; Reddy, J K

    1982-01-01

    The phthalate ester di(2-ethylhexyl) phthalate is both a peroxisome proliferator and a hepatic carcinogen. Peroxisome proliferators as a class are hepatocarcinogenic in rodent species. However, none of the peroxisome proliferators tested to date including the phthalate esters and related alcohol and acid analogs have demonstrated mutagenic or DNA-damaging activity in the in vitro Salmonella typhimurium/microsomal or the lymphocyte 3H-thymidine assays. A working hypothesis is proposed that peroxisome proliferation itself initiates neoplastic transformation of hepatic parenchymal cells by increasing intracellular rates of DNA-damaging reactive oxygen production. Evidence which supports such a hypothesis includes increased fatty acid beta-oxidation, elevated H2O2 levels, accumulation of peroxidized lipofuscin, disproportionately small increase in catalase, and elevated peroxisomal uricase activity which accompany peroxisome proliferation in hepatocytes. Direct testing of this hypothesis will provide insight into mechanisms of phthalate ester carcinogenicity and cytotoxicity. Images FIGURE 1. PMID:6754363

  8. Trimerization of monocyanate ester in nanopores.

    PubMed

    Koh, Yung P; Simon, Sindee L

    2010-06-17

    The effects of nanoconfinement on the reaction kinetics and properties of a monocyanate ester and the resulting cyanurate trimer are studied using differential scanning calorimetry (DSC). On the basis of both dynamic heating scans and isothermal reaction studies, the reaction rate is found to increase with decreasing nanopore size without a change in reaction mechanism. Both the monocyanate ester reactant and cyanurate product show reduced glass transition temperatures (T(g)s) as compared to the bulk; the T(g) depression increases with conversion and is more pronounced for the fully reacted product, suggesting that molecular stiffness influences the magnitude of nanoconfinement effects. Our results are consistent with the accelerated reaction and the T(g) depression found previously for the nanoconfined difunctional cyanate ester, supporting the supposition that intracyclization is not the origin of these effects. PMID:20496921

  9. Routine patch testing with paraben esters.

    PubMed

    Menné, T; Hjorth, N

    1988-09-01

    Paraben esters are the most widely used preservatives in cosmetics and topical medicaments. Their sensitization potential is low, based on both experimental and human experience. A paraben mixture is included in the ICDRG standard series, and in patch test studies, approximately 1% of eczema patients react to it. The present study confirms this frequency in 8020 patients patch tested consecutively. Testing with the individual paraben esters was employed as confirmation, which makes it unlikely that the excited skin syndrome is a significant problem in this context. It remains undetermined whether the present paraben mixture is the optimal patch test material for diagnosing paraben sensitivity. PMID:3191679

  10. Phthalate esters: Testing for ecological effects

    SciTech Connect

    Brown, D.; Thompson, R.; Croudace, C.; Stewart, K.; Williams, N.

    1995-12-31

    Ortho-phthalate esters are produced in high tonnages for use as plasticizers, in particular for PVC. Their physical chemical properties are typically very low water solubility and high octanol/water partition coefficient. This combination of properties presents a number of experimental difficulties in the design and interpretation of ecological effect studies. These difficulties are described and results presented showing techniques for the performance of reproduction studies with the water flea, Daphnia magna, in aqueous solution and with the midge, Chironomus riparius, in sediments. The results which showed no effect for the phthalate esters tested are discussed in the context of other ecotoxicity data obtained on these products.

  11. Adsorption and wettability study of methyl ester sulphonate on precipitated asphaltene

    NASA Astrophysics Data System (ADS)

    Okafor, H. E.; Sukirman, Y.; Gholami, R.

    2016-03-01

    Asphaltene precipitation from crude oil and its subsequent aggregation forms solid, which preferentially deposit on rock surfaces causing formation damage and wettability changes leading to loss of crude oil production. To resolve this problem, asphaltene inhibitor has been injected into the formation to prevent the precipitation of asphaltene. Asphaltene inhibitors that are usually employed are generally toxic and non-biodegradable. This paper presents a new environmentally friendly asphaltene inhibitor (methyl ester sulphonate), an anionic surfactant, which has excellent sorption on formation rock surfaces. Result from adsorption study validated by Langmuir and Freundlich models indicate a favourable adsorption. At low volumes injected, methyl ester sulphonate is capable of reverting oil-wet sandstone surface to water-wet surface. Biodegradability test profile shows that for concentrations of 100-5000ppm it is biodegradable by 65-80%.

  12. Novel Membrane Based Process for Producing Lactate Esters

    SciTech Connect

    1999-02-01

    Lactate Esters from Renewable Carbohydrate Feedstocks can Replace Petroleum-Derived Solvents. Lactate esters are versatile solvents that are biodegradable, nontoxic, and applicable to a wide range of industrial and consumer uses.

  13. Affinity labelling enzymes with esters of aromatic sulfonic acids

    DOEpatents

    Wong, Show-Chu; Shaw, Elliott

    1977-01-01

    Novel esters of aromatic sulfonic acids are disclosed. The specific esters are nitrophenyl p- and m-amidinophenylmethanesulfonate. Also disclosed is a method for specific inactivation of the enzyme, thrombin, employing nitrophenyl p-amidinophenylmethanesulfonate.

  14. Solvent-free enzymatic production of high quality cetyl esters.

    PubMed

    Serrano-Arnaldos, Mar; Máximo-Martín, María Fuensanta; Montiel-Morte, María Claudia; Ortega-Requena, Salvadora; Gómez-Gómez, Elisa; Bastida-Rodríguez, Josefa

    2016-04-01

    A solvent-free biocatalytic process for the synthesis of high quality cetyl laurate, myristate, palmitate and stearate has been optimized. This enzymatic procedure follows the fundamental principles of the Green Chemistry and lead to sustainable products, which can be labeled as natural and conform to the principal requirements for its use in high value-added goods. The four esters selected are the main components of spermaceti, a mixture of waxes very appreciated in cosmetic and pharmacy because of its physical properties and emolliency, which was formerly extracted from the head of the sperm whales. In this paper, the influence of the amount of biocatalyst, the commercially available Novozym(®) 435, and the temperature were studied in an open-air batch reactor before carrying out the synthesis in a high performance vacuum reactor with dry nitrogen input to shift the equilibrium towards product formation. Under optimal conditions, conversion was higher than 98.5 %. The characterization of the enzymatic cetyl esters puts in evidence that these are ultra-pure compounds, which have similar properties to the ones obtained through the conventional industrial processes with the extra benefit of being environmentally friendly. PMID:26801670

  15. Succinate esters: odd-even effects in melting points.

    PubMed

    Joseph, Sumy; Sathishkumar, Ranganathan

    2014-10-01

    Dialkyl succinates show a pattern of alternating behavior in their melting points, as the number of C atoms in the alkane side chain increases, unlike in the dialkyl oxalates [Joseph et al. (2011). Acta Cryst. B67, 525-534]. Dialkyl succinates with odd numbers of C atoms in the alkyl side chain show higher melting points than the immediately adjacent analogues with even numbers. The crystal structures and their molecular packing have been analyzed for a series of dialkyl succinates with 1-4 C atoms in the alkyl side chain. The energy difference (ΔE) between the optimized and observed molecular conformations, density, Kitaigorodskii packing index (KPI) and C-H...O interactions are considered to rationalize this behavior. In contrast to the dialkyl oxalates where a larger number of moderately strong C-H...O interactions were characteristic of oxalates with elevated melting points, here the molecular packing and the density play a major role in raising the melting point. On moving from oxalate to succinate esters the introduction of the C2 spacer adds two activated H atoms to the asymmetric unit, resulting in the formation of stronger C-H...O hydrogen bonds in all succinates. As a result the crystallinity of long-chain alkyl substituted esters improves enormously in the presence of hydrogen bonds from activated donors. PMID:25274517

  16. Hepatoprotective effect of trimethylgallic acid esters against carbon tetrachloride-induced liver injury in rats.

    PubMed

    Sachdeva, Mamta; Chadha, Renu; Kumar, Anil; Karan, Maninder; Singh, Tejvir; Dhingra, Sameer

    2015-12-01

    Gallic acid and its derivatives are potential therapeutic agents for treating various oxidative stress mediated disorders. In the present study, we investigated the hepatoprotective effects of newly synthesized conjugated trimethylgallic acid (TMGA) esters against carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. Animals were pre-treated with TMGA esters at their respective doses for 7 days against CCl4-induced hepatotoxicity. The histopathological changes were evaluated to find out degenerative fatty changes including vacuole formation, inflammation and tissue necrosis. Various biomarkers of oxidative stress (lipid peroxidation, glutathione levels, and endogenous antioxidant enzyme activities), liver enzymes (AST and ALT), triacylglycerol and cholesterol were evaluated. Pre-treatment with TMGA esters (MRG, MGG, MSG, and MUG at the dose of 28.71, 30.03, 31.35, 33.62 mg/kg/day), respectively reversed the CCl4-induced liver injury scores (reduced vacuole formation, inflammation and necrosis), biochemical parameters of plasma (increased AST, ALT, TG, and cholesterol), antioxidant enzymes (increased lipid peroxidation and nitrite levels; decreased glutathione levels, superoxide dismutase and catalase activities) in liver tissues and inflammatory surge (serum TNF-α) significantly. The study revealed that TMGA esters exerted hepatoprotective effects in CCl4-induced rats, specifically by modulating oxidative-nitrosative stress and inflammation. PMID:26742325

  17. Plant-mediated stereoselective biotransformation of phenylglyoxylic acid esters.

    PubMed

    Maczka, Wanda Krystyna; Grabarczyk, Małgorzata; Wińska, Katarzyna; Anioł, Mirosław

    2014-01-01

    Enantioselective reduction of the carbonyl group of three phenylglyoxylic acid esters (methyl, ethyl, and n-propyl esters, 2-4) was conducted using blended plant materials (roots of carrot, beetroot, celeriac and parsley; apple). All used biocatalysts transformed these esters to the corresponding mandelic acid esters with high yield, preferably into the respective R-enantiomer. Butanedione addition improved the enantioselectivity of the reaction. PMID:25265851

  18. Lipid encapsulated docosahexaenoic acid methyl ester

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Encapsulation of structurally sensitive compounds within a solid lipid matrix provides a barrier to prooxidant compounds and effectively limits the extent of oxidative degradation. Encapsulated docosahexaenoic acid (DHA) methyl ester was examined as a model compound for functional foods and feeds. S...

  19. Avocado and olive oil methyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel, the mono-alkyl esters of vegetable oils, animal fats or other triacylglycerol-containing materials and an alternative to conventional petroleum-based diesel fuel, has been derived from a variety of feedstocks. Numerous feedstocks have been investigated as potential biodiesel sources, incl...

  20. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acrylate ester copolymer coating. 175.210 Section... COATINGS Substances for Use as Components of Coatings § 175.210 Acrylate ester copolymer coating. Acrylate ester copolymer coating may safely be used as a food-contact surface of articles intended for...

  1. Synthesis and physical properties of new estolide esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estolides are a class of esters based on vegetable oils that, in this case, are formed when the carboxylic acid functionality of one fatty acid reacts at the site of unsaturation of another fatty acid to form an ester linkage. The objective of this preliminary study was to synthesize new esters of e...

  2. 40 CFR 721.10685 - Phosphoric acid, mixed esters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid, mixed esters (generic... Specific Chemical Substances § 721.10685 Phosphoric acid, mixed esters (generic). (a) Chemical substance... phosphoric acid, mixed esters (PMN P-13-170) is subject to reporting under this section for the...

  3. 40 CFR 721.10431 - Phosphoric acid esters (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Phosphoric acid esters (generic). 721... Substances § 721.10431 Phosphoric acid esters (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as phosphoric acid esters (PMNs...

  4. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  5. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  6. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Vinyl epoxy ester. 721.3140 Section... Substances § 721.3140 Vinyl epoxy ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance vinyl epoxy ester (PMN P-85-527) is subject to reporting under...

  7. 40 CFR 721.10180 - Trifunctional acrylic ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Trifunctional acrylic ester (generic... Specific Chemical Substances § 721.10180 Trifunctional acrylic ester (generic). (a) Chemical substance and... acrylic ester (PMN P-04-692) is subject to reporting under this section for the significant new...

  8. 40 CFR 721.10180 - Trifunctional acrylic ester (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Trifunctional acrylic ester (generic... Specific Chemical Substances § 721.10180 Trifunctional acrylic ester (generic). (a) Chemical substance and... acrylic ester (PMN P-04-692) is subject to reporting under this section for the significant new...

  9. 40 CFR 721.10180 - Trifunctional acrylic ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Trifunctional acrylic ester (generic... Specific Chemical Substances § 721.10180 Trifunctional acrylic ester (generic). (a) Chemical substance and... acrylic ester (PMN P-04-692) is subject to reporting under this section for the significant new...

  10. 40 CFR 721.1732 - Nitrobenzoic acid octyl ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Nitrobenzoic acid octyl ester. 721... Substances § 721.1732 Nitrobenzoic acid octyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as nitrobenzoic acid octyl ester (PMN...

  11. 40 CFR 721.4215 - Hexanedioic acid, diethenyl ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hexanedioic acid, diethenyl ester. 721... Substances § 721.4215 Hexanedioic acid, diethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as hexanedioic acid, diethenyl ester (PMN...

  12. 40 CFR 721.4158 - Hexadecanoic acid, ethenyl ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Hexadecanoic acid, ethenyl ester. 721... Substances § 721.4158 Hexadecanoic acid, ethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as hexadecanoic acid, ethenyl ester (PMN...

  13. 40 CFR 721.1732 - Nitrobenzoic acid octyl ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Nitrobenzoic acid octyl ester. 721... Substances § 721.1732 Nitrobenzoic acid octyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as nitrobenzoic acid octyl ester (PMN...

  14. 40 CFR 721.10431 - Phosphoric acid esters (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Phosphoric acid esters (generic). 721... Substances § 721.10431 Phosphoric acid esters (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as phosphoric acid esters (PMNs...

  15. 40 CFR 721.1732 - Nitrobenzoic acid octyl ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Nitrobenzoic acid octyl ester. 721... Substances § 721.1732 Nitrobenzoic acid octyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as nitrobenzoic acid octyl ester (PMN...

  16. 40 CFR 721.1732 - Nitrobenzoic acid octyl ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Nitrobenzoic acid octyl ester. 721... Substances § 721.1732 Nitrobenzoic acid octyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as nitrobenzoic acid octyl ester (PMN...

  17. 40 CFR 721.5310 - Neononanoic acid, ethenyl ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Neononanoic acid, ethenyl ester. 721... Substances § 721.5310 Neononanoic acid, ethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as neononanoic acid, ethenyl ester (PMN...

  18. 21 CFR 172.735 - Glycerol ester of rosin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Glycerol ester of rosin. 172.735 Section 172.735 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... CONSUMPTION Other Specific Usage Additives § 172.735 Glycerol ester of rosin. Glycerol ester of wood...

  19. 21 CFR 172.735 - Glycerol ester of rosin.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Glycerol ester of rosin. 172.735 Section 172.735 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... CONSUMPTION Other Specific Usage Additives § 172.735 Glycerol ester of rosin. Glycerol ester of wood...

  20. Regioselective ester cleavage during the preparation of bisphosphonate methacrylate monomers

    PubMed Central

    Chougrani, Kamel; Niel, Gilles; Boutevin, Bernard

    2011-01-01

    Summary New functional monomers bearing a methacrylate, a bisphosphonate function and, for most, an internal carboxylate group, were prepared for incorporation into copolymers with adhesive or anticorrosive properties. Methanolysis of some trimethylsilyl bisphosphonate esters not only deprotects the desired bisphosphonate function but also regioselectively cleaves the alkyl ester function without affecting the methacrylate ester. PMID:21512600

  1. 40 CFR 721.5310 - Neononanoic acid, ethenyl ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Neononanoic acid, ethenyl ester. 721... Substances § 721.5310 Neononanoic acid, ethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as neononanoic acid, ethenyl ester (PMN...

  2. 40 CFR 721.4158 - Hexadecanoic acid, ethenyl ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hexadecanoic acid, ethenyl ester. 721... Substances § 721.4158 Hexadecanoic acid, ethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as hexadecanoic acid, ethenyl ester (PMN...

  3. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl ester (generic name). 721.2825... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkyl ester (PMN P-84-968) is subject to reporting under this...

  4. 40 CFR 721.10180 - Trifunctional acrylic ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Trifunctional acrylic ester (generic... Specific Chemical Substances § 721.10180 Trifunctional acrylic ester (generic). (a) Chemical substance and... acrylic ester (PMN P-04-692) is subject to reporting under this section for the significant new...

  5. 21 CFR 556.240 - Estradiol and related esters.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Estradiol and related esters. 556.240 Section 556... Tolerances for Residues of New Animal Drugs § 556.240 Estradiol and related esters. No residues of estradiol, resulting from the use of estradiol or any of the related esters, are permitted in excess of the...

  6. 40 CFR 721.2121 - Thiosubstituted carbonate ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Thiosubstituted carbonate ester... Specific Chemical Substances § 721.2121 Thiosubstituted carbonate ester (generic). (a) Chemical substance... Thiosubstituted carbonate ester (PMN P-99-0654) is subject to reporting under this section for the significant...

  7. 40 CFR 721.2121 - Thiosubstituted carbonate ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Thiosubstituted carbonate ester... Specific Chemical Substances § 721.2121 Thiosubstituted carbonate ester (generic). (a) Chemical substance... Thiosubstituted carbonate ester (PMN P-99-0654) is subject to reporting under this section for the significant...

  8. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  9. 40 CFR 721.1732 - Nitrobenzoic acid octyl ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nitrobenzoic acid octyl ester. 721... Substances § 721.1732 Nitrobenzoic acid octyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as nitrobenzoic acid octyl ester (PMN...

  10. 40 CFR 721.10180 - Trifunctional acrylic ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Trifunctional acrylic ester (generic... Specific Chemical Substances § 721.10180 Trifunctional acrylic ester (generic). (a) Chemical substance and... acrylic ester (PMN P-04-692) is subject to reporting under this section for the significant new...

  11. 40 CFR 721.4158 - Hexadecanoic acid, ethenyl ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Hexadecanoic acid, ethenyl ester. 721... Substances § 721.4158 Hexadecanoic acid, ethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as hexadecanoic acid, ethenyl ester (PMN...

  12. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl ester (generic name). 721.2825... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance alkyl ester (PMN P-84-968) is subject to reporting under this...

  13. 40 CFR 721.3085 - Brominated phthalate ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Brominated phthalate ester. 721.3085... Substances § 721.3085 Brominated phthalate ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as brominated phthalate ester (PMN P-90-581)...

  14. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Brominated aromatic ester. 721.2925... Substances § 721.2925 Brominated aromatic ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN...

  15. QSAR for cholinesterase inhibition by organophosphorus esters and CNDO/2 calculations for organophosphorus ester hydrolysis

    NASA Technical Reports Server (NTRS)

    Johnson, H.; Kenley, R. A.; Rynard, C.; Golub, M. A.

    1985-01-01

    Quantitative structure-activity relationships were derived for acetyl- and butyrylcholinesterase inhibition by various organophosphorus esters. Bimolecular inhibition rate constants correlate well with hydrophobic substituent constants, and with the presence or absence of catonic groups on the inhibitor, but not with steric substituent constants. CNDO/2 calculations were performed on a separate set of organophosphorus esters, RR'P(O)X, where R and R' are alkyl and/or alkoxy groups and X is fluorine, chlorine or a phenoxy group. For each subset with the same X, the CNDO-derived net atomic charge at the central phosphorus atom in the ester correlates well with the alkaline hydrolysis rate constant. For the whole set of esters with different X, two equations were derived that relate either charge and leaving group steric bulk, or orbital energy and bond order to the hydrogen hydrolysis rate constant.

  16. HCV 3a Core Protein Increases Lipid Droplet Cholesteryl Ester Content via a Mechanism Dependent on Sphingolipid Biosynthesis

    PubMed Central

    Alfonso-Garcia, Alba; Branche, Emilie; Conzelmann, Stéphanie; Parisot, Clotilde; Potma, Eric O.; Riezman, Howard; Negro, Francesco

    2014-01-01

    Hepatitis C virus (HCV) infected patients often develop steatosis and the HCV core protein alone can induce this phenomenon. To gain new insights into the pathways leading to steatosis, we performed lipidomic profiling of HCV core protein expressing-Huh-7 cells and also assessed the lipid profile of purified lipid droplets isolated from HCV 3a core expressing cells. Cholesteryl esters, ceramides and glycosylceramides, but not triglycerides, increased specifically in cells expressing the steatogenic HCV 3a core protein. Accordingly, inhibitors of cholesteryl ester biosynthesis such as statins and acyl-CoA cholesterol acyl transferase inhibitors prevented the increase of cholesteryl ester production and the formation of large lipid droplets in HCV core 3a-expressing cells. Furthermore, inhibition of de novo sphingolipid biosynthesis by myriocin - but not of glycosphingolipid biosynthesis by miglustat - affected both lipid droplet size and cholesteryl ester level. The lipid profile of purified lipid droplets, isolated from HCV 3a core-expressing cells, confirmed the particular increase of cholesteryl ester. Thus, both sphingolipid and cholesteryl ester biosynthesis are affected by the steatogenic core protein of HCV genotype 3a. These results may explain the peculiar lipid profile of HCV-infected patients with steatosis. PMID:25522003

  17. 40 CFR 721.10664 - Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., reaction products with alkenoic acid alkyl esters and diamine (generic). 721.10664 Section 721.10664... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10664 Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic)....

  18. 40 CFR 721.10664 - Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., reaction products with alkenoic acid alkyl esters and diamine (generic). 721.10664 Section 721.10664... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10664 Alkenedioic acid dialkyl ester, reaction products with alkenoic acid alkyl esters and diamine (generic)....

  19. Gold‐Catalyzed Intramolecular Cyclizations of Cyclopropenes with Propargylic Esters

    PubMed Central

    Zhu, Peng‐Long

    2015-01-01

    Abstract Homogeneous gold catalysts are interesting as they can act as potent carbophilic Lewis acids to activate the π bonds of alkynes, allenes, and alkenes. Many impressive applications for the formation of C−C or C−heteroatom bonds have been found due to the excellent functional group compatibility of these catalysts and the air and moisture tolerance of their reactions. Here, we have developed gold‐catalyzed novel intramolecular cycloisomerizations of nitrogen or oxygen‐tethered cyclopropenes with propargylic esters. The reaction proceeded through different pathways according to different substituent styles, affording 5‐azaspiro[2.5]oct‐7‐enes and bicyclo[4.1.0]heptanes. PMID:27308208

  20. Functional Characterization of Enzymes Forming Volatile Esters from Strawberry and Banana[w

    PubMed Central

    Beekwilder, Jules; Alvarez-Huerta, Mayte; Neef, Evert; Verstappen, Francel W.A.; Bouwmeester, Harro J.; Aharoni, Asaph

    2004-01-01

    Volatile esters are flavor components of the majority of fruits. The last step in their biosynthesis is catalyzed by alcohol acyltransferases (AATs), which link alcohols to acyl moieties. Full-length cDNAs putatively encoding AATs were isolated from fruit of wild strawberry (Fragaria vesca) and banana (Musa sapientum) and compared to the previously isolated SAAT gene from the cultivated strawberry (Fragaria × ananassa). The potential role of these enzymes in fruit flavor formation was assessed. To this end, recombinant enzymes were produced in Escherichia coli, and their activities were analyzed for a variety of alcohol and acyl-CoA substrates. When the results of these activity assays were compared to a phylogenetic analysis of the various members of the acyltransferase family, it was clear that substrate preference could not be predicted on the basis of sequence similarity. In addition, the substrate preference of recombinant enzymes was not necessarily reflected in the representation of esters in the corresponding fruit volatile profiles. This suggests that the specific profile of a given fruit species is to a significant extent determined by the supply of precursors. To study the in planta activity of an alcohol acyltransferase and to assess the potential for metabolic engineering of ester production, we generated transgenic petunia (Petunia hybrida) plants overexpressing the SAAT gene. While the expression of SAAT and the activity of the corresponding enzyme were readily detected in transgenic plants, the volatile profile was found to be unaltered. Feeding of isoamyl alcohol to explants of transgenic lines resulted in the emission of the corresponding acetyl ester. This confirmed that the availability of alcohol substrates is an important parameter to consider when engineering volatile ester formation in plants. PMID:15326278

  1. Modified branched-chain amino acid pathways give rise to acyl acids of sucrose esters exuded from tobacco leaf trichomes.

    PubMed

    Kandra, G; Severson, R; Wagner, G J

    1990-03-10

    A major diversion of carbon from branched-chain amino acid biosynthesis/catabolism to form acyl moieties of sucrose esters (6-O-acetyl-2,3,4-tri-O-acyl-alpha-D-glucopyranosyl-beta-D- fructofuranosides) was observed to be associated with specialized trichome head cells which secrete large amounts of sucrose esters. Surface chemistry and acetyl and acyl substituent groups of tobacco (T.I. 1068) sucrose esters were identified and quantified by gas chromatography/mass spectrometry. Sucrose esters were prominent surface constituents and 3-methylvaleric acid, 2- and 3-methylbutyric acid, and methylpropionic acid accounted for 60%, 25% and 9%, respectively, of total C3--C7 acyl substituents. Radiolabeled Thr, Ile, Val, Leu, pyruvate and Asp, metabolites of branched-chain amino acid pathways, were compared with radioactively labeled acetate and sucrose as donors of carbon to sucrose, acetyl and acyl components of sucrose esters using epidermal peels with undisturbed trichomes. Preparations of biosynthetically competent trichome heads (site of sucrose ester formation) were also examined. Results indicate that 3-methylvaleryl and 2-methylbutyryl groups are derived from the Thr pathway of branched-chain amino acid metabolism, 3-methylbutyryl and methylpropionyl groups are formed via the pyruvate pathway, and that acetyl groups are principally formed directly via acetyl-CoA. Arguments are presented which rule out participation of fatty acid synthase in the formation of prominent acyl acids. Results suggest that the shunting of carbon away from the biosynthesis of Val, Leu and Ile may be due to a low level of amino acid utilization in protein synthesis in specialized glandular head cells of trichomes. This would result in the availability of corresponding oxo acids for CoA activation and esterification to form sucrose esters. Preliminary evidence was found for the involvement of cycling reactions in oxo-acid-chain lengthening and for utilization of pyruvate-derived 2

  2. Unambiguous identification of esters as oligomers in secondary organic aerosol formed from cyclohexene and cyclohexene/α-pinene ozonolysis

    NASA Astrophysics Data System (ADS)

    Müller, L.; Reinnig, M.-C.; Warnke, J.; Hoffmann, T.

    2007-09-01

    The built-up of oligomeric compounds during secondary organic aerosol (SOA) formation is subject of atmospheric research since several years. New particle formation and especially the SOA mass yield might be influenced significantly by oligomer formation. However, the chemical nature of observed oligomers and their formation pathways are still unclear. In this paper, the structural characterization of certain dimeric compounds (esters) formed during the ozonolysis of cyclohexene and cyclohexene/α-pinene mixtures are presented. The identification is based on the comparison of the mass spectra and the retention times (LC) of the oligomeric products with synthesized reference compounds. Cyclohexene is used here as a model compound for terpenes as globally most important SOA precursors, since it possesses a simpler structure than the biogenic alkenes and therefore offers the possibility to get access to reference compounds for certain of its oxidation products. In addition to cyclohexene, the formation of esters could also be observed in experiments with α-pinene as reactant.

  3. Unambiguous identification of esters as oligomers in secondary organic aerosol formed from cyclohexene and cyclohexene/α-pinene ozonolysis

    NASA Astrophysics Data System (ADS)

    Müller, L.; Reinnig, M.-C.; Warnke, J.; Hoffmann, Th.

    2008-03-01

    The build-up of oligomeric compounds during secondary organic aerosol (SOA) formation is subject of atmospheric research since several years. New particle formation and especially the SOA mass yield might be influenced significantly by oligomer formation. However, the chemical nature of observed oligomers and their formation pathways are still unclear. In this paper, the structural characterization of certain dimeric compounds (esters) formed during the ozonolysis of cyclohexene and cyclohexene/α-pinene mixtures are presented. The identification is based on the comparison of the mass spectra and the retention times (LC) of the oligomeric products with synthesized reference compounds. Cyclohexene is used here as a model compound for terpenes as globally most important SOA precursors, since it possesses a simpler structure than the biogenic alkenes and therefore offers the possibility to get access to reference compounds for certain of its oxidation products. In addition to cyclohexene, the formation of esters could also be observed in experiments with α-pinene as reactant.

  4. Photoenolization of o-Methylvalerophenone Ester Derivative.

    PubMed

    Das, Anushree; Lao, Emily A; Gudmundsdottir, Anna D

    2016-05-01

    Photolysis of ester 1 in argon-saturated methanol and acetonitrile does not produce any product, whereas irradiation of 1 in oxygen-saturated methanol yields peroxide 2. Laser flash photolysis studies demonstrate that 1 undergoes intramolecular H atom abstraction to form biradical 3 (λmax ~340 nm), which intersystem crosses to form photoenols Z-4 and E-4 (λmax ~380 nm). Photoenols 4 decay by regenerating ester 1. With the aid of density functional theory calculations, it was concluded the photoenol E-4 does not undergo spontaneous lactonization or electrocyclic ring closure because the transition state barriers for these reactions are too large to compete with reketonization of E-4 to form 1. PMID:27061950

  5. Identification of Neutral Cholesterol Ester Hydrolase, a Key Enzyme Removing Cholesterol from Macrophages*S⃞

    PubMed Central

    Okazaki, Hiroaki; Igarashi, Masaki; Nishi, Makiko; Sekiya, Motohiro; Tajima, Makiko; Takase, Satoru; Takanashi, Mikio; Ohta, Keisuke; Tamura, Yoshiaki; Okazaki, Sachiko; Yahagi, Naoya; Ohashi, Ken; Amemiya-Kudo, Michiyo; Nakagawa, Yoshimi; Nagai, Ryozo; Kadowaki, Takashi; Osuga, Jun-ichi; Ishibashi, Shun

    2008-01-01

    Unstable lipid-rich plaques in atherosclerosis are characterized by the accumulation of macrophage foam cells loaded with cholesterol ester (CE). Although hormone-sensitive lipase and cholesteryl ester hydrolase (CEH) have been proposed to mediate the hydrolysis of CE in macrophages, circumstantial evidence suggests the presence of other enzymes with neutral cholesterol ester hydrolase (nCEH) activity. Here we show that the murine orthologue of KIAA1363, designated as neutral cholesterol ester hydrolase (NCEH), is a microsomal nCEH with high expression in murine and human macrophages. The effect of various concentrations of NaCl on its nCEH activity resembles that on endogenous nCEH activity of macrophages. RNA silencing of NCEH decreases nCEH activity at least by 50%; conversely, its overexpression inhibits the CE formation in macrophages. Immunohistochemistry reveals that NCEH is expressed in macrophage foam cells in atherosclerotic lesions. These data indicate that NCEH is responsible for a major part of nCEH activity in macrophages and may be a potential therapeutic target for the prevention of atherosclerosis. PMID:18782767

  6. Synthesis of enantiopure cyclopropyl esters from (-)-levoglucosenone.

    PubMed

    Stockton, Kieran P; Greatrex, Ben W

    2016-08-21

    The biorenewable chiral synthon (-)-levoglucosenone has been converted to enantiopure cyclopropyl esters using the base-promoted carbocyclisation of 4,5-epoxyvalerates. This protocol was applied to the enantiospecific synthesis of the GABAc receptor agonist (1R,2R)-trans-2-aminomethylcyclopropanecarboxylic acid ((-)-TAMP) and its enantiomer. The process was also extended to generate 1,1,2- and 1,2,3-trisubstituted cyclopropanes resulting in a formal synthesis of the selective glutamate receptor antagonist PCCG-4. PMID:27424764

  7. Bacteriopheophorbide esters: photosensitizers without "threshold dose"?

    NASA Astrophysics Data System (ADS)

    Moser, Joerg G.; Ostrowsky, Andreas; Guemuesdagli, Maria; Kleiber, Beate

    1994-03-01

    Uptake and phototoxicity of the methyl-, ethyl-, n-propyl, and 2-propyl esters of 132- hydroxy bacteriopheophorbide a were studied in OAT 75 SCLC cells and 3 different amelanotic melanoma cell lines. (A 375, Melur SP 18, SkAMel 25). Specific phototoxicity did not substantially differ for the different esters. Most surprisingly, these photosensitizers did not show any significant threshold behavior: even at 25 (mu) W/cm2 (775 nm, diode laser) cancer cell suspensions were killed in a time-dependent logarithmic fashion. Furthermore, phototoxicity is enhanced at low power densities if compared with the effects at 1 - 10 mW/cm2. This can be related only in part to a lack of oxygen at higher power densities. Complementary experiments confirmed that threshold is power but not dose dependent. Thus, threshold power density should be included into a prospective list of criteria characterizing photosensitizers suitable for photodynamic cancer therapy. The obvious lack of a limiting power density in bacteriopheophobide a esters make these sensitizers a prospective tool for tumor therapy in considerable tissue depth.

  8. Calorimetric study of peroxycarboxylic ester synthesis.

    PubMed

    Fritzsche, L; Knorr, A

    2009-04-30

    Exothermic reactions involving organic peroxides carry a high potential hazard and must be considered with care. A safe handling requires, among others, the assessment of thermal process safety, for which safety characteristics like overall heat production and the resulting adiabatic temperature rise are essential. The article presents the results of the calorimetric investigation of the synthesis of four peroxycarboxylic esters, three tert-Butyl and one tert-Amyl peroxycarboxylic ester. In the two-step synthesis the second one clearly shows the higher exothermic potential. The overall heat production lies in the range of 126-135 kJ/mol and is nearly independent of the carboxylic acid residual in the tert-Butyl peroxycarboxylic ester. The calculated adiabatic temperature rise is 70-80K. Influence of temperature and feed rate on the heat generation is discussed for one species. A grading of the synthesis with respect to temperature levels according to the criticality classes by Stoessel leads to the most critical for an exothermic reaction. PMID:18722058

  9. Optimization of ethyl ester production assisted by ultrasonic irradiation.

    PubMed

    Noipin, K; Kumar, S

    2015-01-01

    This study presents the optimization of the continuous flow potassium hydroxide-catalyzed synthesis of ethyl ester from palm oil with ultrasonic assistance. The process was optimized by application of factorial design and response surface methodology. The independent variables considered were ethanol to oil molar ratio, catalyst concentration, reaction temperature and ultrasonic amplitude; and the response was ethyl ester yield. The results show that ethanol to oil molar ratio, catalyst concentration, and ultrasonic amplitude have positive effect on ethyl ester yield, whereas reaction temperature has negative influence on ethyl ester yield. Second-order models were developed to predict the responses analyzed as a function of these three variables, and the developed models predicts the results in the experimental ranges studied adequately. This study shows that ultrasonic irradiation improved the ethyl ester production process to achieve ethyl ester yields above 92%. PMID:25116594

  10. 18-Membered cyclic esters derived from glycolide and lactide: preparations, structures and coordination to sodium ions

    SciTech Connect

    Chisholm, Malcolm H.; Gallucci, Judith C.; Yin, Hongfeng

    2008-06-30

    From reactions between glycolide or lactide (4 equiv.) with 4-dimethylaminopyridine, DMAP (1 equiv.) and NaBPh4 (1 equiv.) in benzene at 70 C the cyclic ester adducts (CH{sub 2}C(O)O){sub 6}NaBPh{sub 4} and (CHMeC(O)O){sub 6}NaBPh{sub 4} are formed respectively. The structures of the salts Na[(S,R,S,R,S,R)-(CH{sub 3}CHC(O)O){sub 6}]{sub 2}BPh{sub 4} {center_dot} CH{sub 3}CN and (CH{sub 2}C(O)O){sub 6}NaBPh{sub 4} {center_dot} (CH{sub 3}CN){sub 2} are reported. The cyclic esters were separated by chromatography and the structures of (CH{sub 2}C(O)O){sub 6}, (S,R,R,R,R,R)-(CHMeC(O)O){sub 6} and (S,S,R,R,R,R)-(CHMeC(O)O){sub 6} were determined. The {sup 1}H and {sup 13}C NMR data are reported for one of each of the six enantiomers of (CHMeC(O)O){sub 6} and the two meso isomers. The mechanism for the formation of these 18-membered rings is discussed in terms of an initial reaction between DMAP and NaBPh{sub 4} in hot benzene that produces NaPh and DMAP:BPh{sub 3} in the presence of the monomer lactide. The cyclic esters (CHMeC(O)O){sub 6} can also be obtained from the reaction between polylactide, PLA, in the presence of DMAP and NaBPh{sub 4}. The cyclic esters 3-methyl-1,4-dioxane-2,5-dione and 3,6,6-trimethyl-1,4-dioxane-2,5-dione undergo similar ring enlarging reactions to give cyclic 18-membered ring esters as determined by ESI-MS.

  11. Carboxylesterase-dependent cytotoxicity of dibasic esters (DBE) in rat nasal explants.

    PubMed

    Trela, B A; Bogdanffy, M S

    1991-02-01

    Dibasic esters (DBE) are a solvent mixture of dimethyl adipate (DMA), dimethyl glutarate (DMG), and dimethyl succinate (DMS) used in the paint and coating industry. Subchronic inhalation toxicity studies have demonstrated that DBE induce a mild degeneration of the olfactory, but not the respiratory, epithelium of the rat nasal cavity. Carboxylesterase-mediated hydrolysis of the individual dibasic esters is more efficient in olfactory than in respiratory mucosal homogenates. In the present study, an in vitro system of cultured rat nasal explants was utilized to determine if DBE toxicity is dependent on a metabolic activation by nonspecific carboxylesterase. Explants from both the olfactory and the respiratory regions of the female rat nasal cavity were incubated for 2 hr in Williams' medium E containing 10-100 mM DMA, DMG, or DMS. DBE caused a dose-related increase in nasal explant acid phosphatase release, a biochemical index of cytotoxicity. HPLC analysis demonstrated parallel increases in the carboxylesterase-mediated formation of monomethyl ester metabolites. Diacid metabolite production in the nasal explant system was not entirely concentration-dependent. Metabolite concentrations and acid phosphatase release were generally greater in olfactory than respiratory tissues. DBE-induced cytotoxicity and acid metabolite production were markedly attenuated in nasal tissue excised from rats which were pretreated with bis(p-nitrophenyl)phosphate, a carboxylesterase inhibitor. This study presents a viable in vitro method for assessing organic ester cytotoxicity in the rat nasal cavity. It was shown that DBE are weak nasal toxicants under the conditions of this system. It was further demonstrated that DBE toxicity is dependent on a carboxylesterase-mediated activation. A similar mechanism was proposed for the nasal toxicity induced by other organic esters following inhalation exposure. PMID:1994511

  12. Acretoside, a new sucrose ester from Aristolochia cretica.

    PubMed

    Georgopoulou, C; Aligiannis, N; Fokialakis, N; Mitaku, S

    2005-12-01

    A new sucrose ester, acretoside, has been isolated from the roots of the Greek endemic species Aristolochia cretica and identified as 6-O-p-coumaroyl-beta-D-fructofuranosyl-(2 --> 1)-alpha-D-glucopyranoside (1). In addition, a known sucrose ester, identified as arillatose B, two phenylpropanoid glucose esters, and five derivatives of aristolochic acids have been isolated. Their structures have been elucidated on the basis of MS and NMR data. PMID:16308194

  13. The Saccharomyces cerevisiae YLL012/YEH1, YLR020/YEH2, and TGL1 genes encode a novel family of membrane-anchored lipases that are required for steryl ester hydrolysis.

    PubMed

    Köffel, René; Tiwari, Rashi; Falquet, Laurent; Schneiter, Roger

    2005-03-01

    Sterol homeostasis in eukaryotic cells relies on the reciprocal interconversion of free sterols and steryl esters. The formation of steryl esters is well characterized, but the mechanisms that control steryl ester mobilization upon cellular demand are less well understood. We have identified a family of three lipases of Saccharomyces cerevisiae that are required for efficient steryl ester mobilization. These lipases, encoded by YLL012/YEH1, YLR020/YEH2, and TGL1, are paralogues of the mammalian acid lipase family, which is composed of the lysosomal acid lipase, the gastric lipase, and four novel as yet uncharacterized human open reading frames. Lipase triple-mutant yeast cells are completely blocked in steryl ester hydrolysis but do not affect the mobilization of triacylglycerols, indicating that the three lipases are required for steryl ester mobilization in vivo. Lipase single mutants mobilize steryl esters to various degrees, indicating partial functional redundancy of the three gene products. Lipase double-mutant cells in which the third lipase is expressed from the inducible GAL1 promoter have greatly reduced steady-state levels of steryl esters, indicating that overexpression of any of the three lipases is sufficient for steryl ester mobilization in vivo. The three yeast enzymes constitute a novel class of membrane-anchored lipases that differ in topology and subcellular localization. PMID:15713625

  14. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) The acrylate ester copolymer is a fully polymerized copolymer of ethyl acrylate, methyl methacrylate... emulsion defoamer. Disodium hydrogen phosphate Do. Formaldehyde Glyceryl monostearate Methyl...

  15. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) The acrylate ester copolymer is a fully polymerized copolymer of ethyl acrylate, methyl methacrylate... emulsion defoamer. Disodium hydrogen phosphate Do. Formaldehyde Glyceryl monostearate Methyl...

  16. Synthesis and evaluation of antiinflammatory activities of a series of corticosteroid 17 alpha-esters containing a functional group.

    PubMed

    Ueno, H; Maruyama, A; Miyake, M; Nakao, E; Nakao, K; Umezu, K; Nitta, I

    1991-08-01

    A series of 21-desoxy-21-chlorocorticosteroids that contain a functionalized ester group at 17 alpha has been prepared and examined to separate their systemic activity from topical antiinflammatory activity. Introduction of the functionalized ester group at 17 alpha was carried out by an acid-catalyzed formation of cyclic ortho esters with 17 alpha,21-hydroxyl groups of corticosteroids and subsequent acid-catalyzed hydrolysis. As for the functional group, chloro, methoxy, acetoxy, cyano, cyclopropyl, or alkoxycarbonyl group was introduced at the terminal carbon atom of the 17 alpha-alkanoate group. The topical antiinflammatory activity and systemic activity of these compounds were examined and found to be significantly dependent on the functionalities in the 17 alpha-esters. Among these derivatives, a series of 17 alpha-(alkoxycarbonyl)alkanoates (17 alpha-OCO(CH2)nCOOR) showed an excellent separation of the systemic activity from topical activity. The effects of the number of methylene groups (n) and of the alkyl groups of the ester (R) on either topical or systemic activity of the corticosteroid derivatives were also investigated. PMID:1875343

  17. Tandem transformation of glycerol to esters.

    PubMed

    Sotenko, Maria V; Rebroš, Martin; Sans, Victor S; Loponov, Konstantin N; Davidson, Matthew G; Stephens, Gill; Lapkin, Alexei A

    2012-12-31

    Tandem transformation of glycerol via microbial fermentation and enzymatic esterification is presented. The reaction can be performed with purified waste glycerol from biodiesel production in a continuous mode, combining continuous fermentation with membrane-supported enzymatic esterification. Continuous anaerobic fermentation was optimized resulting in the productivity of 2.4 g L⁻¹ h⁻¹ of 1,3-propanediol. Biphasic esterification of 1,3-propanediol was optimized to achieve ester yield of up to 75%. A hollow fibre membrane contactor with immobilized Rhizomucor miehei lipase was demonstrated for the continuous tandem fermentation-esterification process. PMID:22796408

  18. New jatrophane diterpenoid esters from Euphorbia turczaninowii.

    PubMed

    Liu, L G; Tan, R X

    2001-08-01

    Five new (1-5) and one known (6) jatrophane diterpenoid esters were isolated from the ethanol extract of the whole herb of Euphorbia turczaninowii. Their structures were established by extensive spectroscopic methods. The absolute stereochemistry of 3 beta,5 alpha,8 alpha,15 beta-tetraacetoxy-7 beta-benzoyloxyjatropha-6(17),11E-dien-9,14-dione (1) was confirmed by a single-crystal X-ray analysis coupled with the exciton chirality circular dichroism method. Compounds 1-6 were inactive when evaluated both in a mouse ear inflammation assay and for cytotoxicity against the B16 mouse melanoma cell line. PMID:11520228

  19. Effects of high-melting methyl esters on crystallization properties of fatty acid methyl ester mixtures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is a renewable alternative diesel fuel made from vegetable oils and animal fats. The most common form of biodiesel in the United States are fatty acid methyl esters (FAME) from soybean, canola, and used cooking oils, waste greases, and tallow. Cold flow properties of biodiesel depend on th...

  20. Surface Tension Studies of Alkyl Esters and Epoxidized Alkyl Esters Relevant to Oleochemically Based Fuel Additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the surface tension of several epoxidized oleochemicals and their comparable fatty esters at temperatures between 25 and 60 deg C. Surface tensions of the olefins measured at 40 deg C range from 25.9 mN m-1, for isobutyl oleate, to 28.4 mN m-1 for methyl linoleate. The epoxy versions of ...

  1. Cholesteryl ester transfer activity. Localization and role in distribution of cholesteryl ester among lipoproteins in man.

    PubMed

    Groener, J E; Van Rozen, A J; Erkelens, D W

    1984-03-01

    The cholesteryl ester exchange/transfer protein is involved in the transport of cholesteryl ester from high density lipoproteins (HDL) to very low density lipoproteins (VLDL) and low density lipoproteins (LDL). Localization of cholesteryl ester transfer activity (CETA) in plasma was studied by measuring CETA in various delipidated fractions from a single step density ultracentrifugation gradient of plasma. CETA was measured in an in vitro system by calculating the exchange of cholesteryl ester in a standard mixture of [3H]CE-HDL and LDL. The method used for the delipidation of plasmas and fractions to be tested was critical. Optimal results were obtained by delipidation with diisopropylether-butanol (60: 40, v/v) at O degrees C. The bulk of CETA was detected in HDL3 (1.125 less than d less than 1.210 g/ml) when the lipoproteins were separated by single-step density gradient ultracentrifugation and in the 'lipoprotein-free' fraction (d greater than 1.250 g/ml) when the lipoproteins were separated by flotation ultracentrifugation including two washes. To determine whether CETA plays a role in the distribution of cholesteryl ester among the various lipoproteins, it was measured in whole plasma from normal and hyperlipidemic subjects. Plasma was delipidated before the assay in order to prevent bias due to variation of cholesterol content. CETA was higher in delipidated plasma of hyperlipidemic subjects (117.3 +/- 36.5 nmol CE/ml/h) than in delipidated plasma of normolipidemic controls (68.7 +/- 17.6 nmol CE/ml/h) (P less than 0.005). A positive correlation (r = 0.80, P less than 0.005) was found between CETA and (VLDL + LDL) cholesterol levels. A negative correlation (r = 0.57, P less than 0.05) existed between CETA and HDL cholesterol. This correlation was found both in the group as a whole and within the normal and the hyperlipidemic groups separately. The activity of the cholesteryl ester transfer appears to be a regulatory factor in the distribution of cholesteryl

  2. Biological activity and ESI MS study of oxaalkyl and hydroksyoxaalkyl lasalocid esters

    NASA Astrophysics Data System (ADS)

    Pankiewicz, Radosław; Remlein-Starosta, Dorota; Schroeder, Grzegorz; Brzezinski, Bogumił

    2006-02-01

    Eight lasalocid esters (Las1)-(Las8) have been synthesised and their complex formation with Mg 2+ and Ca 2+ cations has been studied by ESI MS and PM5 semiempirical method. The ESI MS spectra of the complexes have shown that Las1-8 forms stable 1:1 complexes with Mg 2+ and Ca 2+ cations. The ESI MS spectra at higher cone voltage values have revealed the m/ z peaks characteristic of the abstraction of one proton from the complex molecule. The calculated structures of Las1-8 with Mg 2+ and Ca 2+ cations are compared with those of the respective 1:1 complexes with monovalent cations. The biological activity of the esters on pathogenic bacteria Ervinia carotovora and fungus Fusariumoxysporum has been studied in vitro and some biological active compounds have been identified. This result can be very important for future applications in agriculture.

  3. Water chemical ionization mass spectrometry of aldehydes, ketones esters, and carboxylic acids

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.

    1986-11-01

    Chemical ionization mass spectrometry (CI) of aliphatic and aromatic carbonyl compounds using water as the reagent gas provides intense pseudomolecular ions and class-specific fragmentation patterns that can be used to identify aliphatic aldehydes, ketones, carboxylic acids, and esters. The length of ester acyl and alkyl groups can easily be determined on the basis of loss of alcohols from the protonated parent. Water CI provides for an approximately 200:1 selectivity of carbonyl species over alkanes. No reagent ions are detected above 55 amu, allowing species as small as acetone, propanal, acetic acid, and methyl formate to be identified. When deuterate water was used as the reagent, only the carboxylic acids and ..beta..-diketones showed significant H/D exchange. The use of water CI to identify carbonyl compounds in a wastewater from the supercritical water extraction of lignite coal, in lemon oil, and in whiskey volatiles is discussed.

  4. Functional group analysis during ozonation of sunflower oil methyl esters by FT-IR and NMR.

    PubMed

    Soriano, Nestor U; Migo, Veronica P; Matsumura, Masatoshi

    2003-12-01

    Ozonation of neat sunflower oil (SFO) methyl esters was monitored by FT-IR and 1H and 13C NMR spectroscopy. During the early stage of ozonation, ozone absorption was essentially quantitative. This was accompanied by the formation of 1,2,4-trioxolane. IR and NMR spectra of ozonated samples showed that scission of ozonide to give aldehyde were minimal. 1H NMR analysis revealed that the amount of ozonide relative to aldehyde was more than 90% regardless of the extent of ozonation. Complete ozonation was attained after supplying around 0.20 g O3/ml methyl ester after which ozone absorption suddenly dropped to around 25%. At the latter part of ozonation, ozonide and aldehyde reacted with excess ozone to give carboxylic acid. Reaction products were identified according to Criegee mechanism. PMID:14623448

  5. The effect of frying on glycidyl esters content in palm oil.

    PubMed

    Aniołowska, Magda; Kita, Agnieszka

    2016-07-15

    The changes in palm oil, as affected by frying temperature, and content of the glycidyl esters (GEs) were studied. Potato chips were fried intermittently in palm oil, which was heated for 8 h daily over five consecutive days. Frying was conducted at three frying temperatures: 150, 165 and 180 °C. Thermo-oxidative alterations of the oil were measured by acid and anisidine values, changes in fatty acid composition, total polar components, polar fraction composition and colour components formation. Content of GE was measured by liquid chromatography-mass spectrometry. Results showed that amount of products of hydrolysis, oxidation and polymerization (excluding decrease of degree of unsaturation) increased significantly as a function of frying temperature and time. Between GEs of fatty acids the most abundant were esters of palmitic and oleic acids. With increasing temperature and frying time, the content of GE decreased. The extent of GE decrease was correlated with degree of oil degradation. PMID:26948594

  6. Direct Determination of MCPD Fatty Acid Esters and Glycidyl Fatty Acid Esters in Vegetable Oils by LC–TOFMS

    PubMed Central

    Haines, Troy D.; Adlaf, Kevin J.; Pierceall, Robert M.; Lee, Inmok; Venkitasubramanian, Padmesh

    2010-01-01

    Analysis of MCPD esters and glycidyl esters in vegetable oils using the indirect method proposed by the DGF gave inconsistent results when salting out conditions were varied. Subsequent investigation showed that the method was destroying and reforming MCPD during the analysis. An LC time of flight MS method was developed for direct analysis of both MCPD esters and glycidyl esters in vegetable oils. The results of the LC–TOFMS method were compared with the DGF method. The DGF method consistently gave results that were greater than the LC–TOFMS method. The levels of MCPD esters and glycidyl esters found in a variety of vegetable oils are reported. MCPD monoesters were not found in any oil samples. MCPD diesters were found only in samples containing palm oil, and were not present in all palm oil samples. Glycidyl esters were found in a wide variety of oils. Some processing conditions that influence the concentration of MCPD esters and glycidyl esters are discussed. PMID:21350591

  7. Long-lived testosterone esters in the rat.

    PubMed Central

    Borg, W; Shackleton, C H; Pahuja, S L; Hochberg, R B

    1995-01-01

    Over the past decade it has become increasingly clear that steroid hormones are enzymatically esterified with fatty acids. These steroidal esters are the natural analogs of synthetic esters that are used therapeutically. One such family of pharmacological steroids is the synthetic alkyl esters of testosterone, androgens with great hormonal potency. We have investigated whether testosterone esters exist naturally by using the rat as a model. Most tissues of male rats, including blood, have very little if any ester (quantified by immunoassay as a nonpolar saponifiable metabolite), but fat and testes have sizable quantities, approximately 3 ng of testosterone equivalents per g of tissue. Testosterone in fat averages 9 ng/g. The fat from female rats and long-term (> 2 weeks) castrated males has no detectable testosterone ester. The presence of testosterone esters was confirmed by GC/MS, which clearly showed the presence of testosterone in the hydrolyzed ester fraction of fat from intact males but not long-term castrates. Upon castration, testosterone levels in the fat completely disappear within 6 hr. To the contrary, it is not until 48 hr after castration that a measurable fall in the testosterone ester fraction was observed; even after 10 days a small amount of ester is still present in the fat. These experiments demonstrate the existence of a previously unknown androgen with a potentially important physiological impact; testosterone esters, natural analogs of potent therapeutic agents, occur in the fat where they can serve as a reservoir of preformed androgen to stimulate neighboring target tissues. Images Fig. 2 PMID:7878017

  8. Are Polyphosphates or Phosphate Esters Prebiotic Reagents?

    NASA Technical Reports Server (NTRS)

    Keefe, Anthony D.; Miller, Stanley L.

    1995-01-01

    It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in nature, the efficiency of the volcanic synthesis of P4O10, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources.

  9. 40 CFR 721.3140 - Vinyl epoxy ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Vinyl epoxy ester. 721.3140 Section 721.3140 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.3140 Vinyl epoxy ester. (a)...

  10. 40 CFR 721.8660 - Propionic acid methyl ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Propionic acid methyl ester (generic... Substances § 721.8660 Propionic acid methyl ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a propionic acid methyl...

  11. 40 CFR 721.8660 - Propionic acid methyl ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Propionic acid methyl ester (generic... Substances § 721.8660 Propionic acid methyl ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a propionic acid methyl...

  12. 40 CFR 721.3080 - Substituted phosphate ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Substituted phosphate ester (generic... Substances § 721.3080 Substituted phosphate ester (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted phosphate...

  13. 40 CFR 721.3080 - Substituted phosphate ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted phosphate ester (generic... Substances § 721.3080 Substituted phosphate ester (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted phosphate...

  14. 40 CFR 721.10255 - Vinyl carboxylic acid ester (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Vinyl carboxylic acid ester (generic... Specific Chemical Substances § 721.10255 Vinyl carboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  15. 40 CFR 721.10255 - Vinyl carboxylic acid ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Vinyl carboxylic acid ester (generic... Specific Chemical Substances § 721.10255 Vinyl carboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  16. 40 CFR 721.10255 - Vinyl carboxylic acid ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Vinyl carboxylic acid ester (generic... Specific Chemical Substances § 721.10255 Vinyl carboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  17. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Alkyl ester (generic name). 721.2825 Section 721.2825 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject...

  18. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Alkyl ester (generic name). 721.2825 Section 721.2825 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject...

  19. 40 CFR 721.2825 - Alkyl ester (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Alkyl ester (generic name). 721.2825 Section 721.2825 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... Substances § 721.2825 Alkyl ester (generic name). (a) Chemical substance and significant new uses subject...

  20. The Preparation and Enzymatic Hydrolysis of a Library of Esters

    ERIC Educational Resources Information Center

    Sanford, Elizabeth M.; Smith, Traci L.

    2008-01-01

    An investigative case study involving the preparation of a library of esters using Fischer esterification and alcoholysis of acid chlorides and their subsequent enzymatic hydrolysis by pig liver esterase and orange peel esterase is described. Students work collaboratively to prepare and characterize the library of esters and complete and evaluate…

  1. Physical and monolayer film properties of potential fatty ester biolubricants

    SciTech Connect

    Yao, Linxing; Hammond, Earl G; Wang, Tong; Bu, Wei; Vaknin, David

    2014-04-03

    The desire to replace petroleum-based lubricants with alternatives that are environmentally friendly and made from sustainable sources has encouraged the development of biolubricants based on vegetable oils. To be good lubricants, the materials should have low melting points, appropriate viscosity and oxidative stability. In this paper, we report the melting point and viscosity of oleate esters of ethylene glycol, 1,2-propanediol, 2,3-butanediol, and pentaerythritol as well as the decanoate esters of 2,3-butanediol and the 12-methyltetradecanoate esters of 1,2-propanediol. Polyol esters that have a free hydroxy group had lower melting points than the completely esterified polyols, but the completely esterified polyol esters exhibited less change in viscosity with temperature than those having a free hydroxy group. 2, 3-Butanediol monooleate, which melted at -48.6°C shows promise as a biolubricant, but its viscosity index was estimated to be 100. Pentaerythritol oleate esters, with melting points below -10°C and viscosity indices in the range of 170–197, may be suitable candidates as biolubricants. The behavior of esters spread as a monomolecular film at air/water interface may provide insight into the way they behave when spread on metal or polar surfaces, so the pressure-area isotherms of 2,3-butanediol monoleate and selected esters are also reported.

  2. MICROBIAL TRANSFORMATION OF ESTERS OF CHLORINATED CARBOXYLIC ACIDS

    EPA Science Inventory

    Two groups of compounds were selected for microbial transformation studies. In the first group were carboxylic acid esters having a fixed aromatic moiety and an increasing length of the alkyl component. Ethyl esters of chlorine-substituted carboxylic acids were in the second grou...

  3. Lipoate ester models for multi-functional lubricant additives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven lipoate esters were synthesized by esterification of lipoic acid with different structures of alcohols in the presence of a solid acid catalyst and without solvent. The esters were obtained in good yield, characterized using 1H NMR and GPC; and their physical properties investigated. Four of t...

  4. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  5. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  6. 40 CFR 721.3110 - Polycarboxylic acid ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polycarboxylic acid ester (generic... Substances § 721.3110 Polycarboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polycarboxylic acid...

  7. Preparation of .alpha.,.beta.-unsaturated carboxylic acids and esters

    DOEpatents

    Gogate, Makarand Ratnakar; Spivey, James Jerry; Zoeller, Joseph Robert

    1998-01-01

    Disclosed is a process for the preparation of .alpha.,.beta.-unsaturated carboxylic acids and esters thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic acid, ester or anhydride in the presence of a catalyst comprising an oxide of niobium.

  8. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  9. 40 CFR 721.3110 - Polycarboxylic acid ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polycarboxylic acid ester (generic... Substances § 721.3110 Polycarboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polycarboxylic acid...

  10. Preparation of {alpha},{beta}-unsaturated carboxylic acids and esters

    DOEpatents

    Gogate, M.R.; Spivey, J.J.; Zoeller, J.R.

    1998-09-15

    Disclosed is a process for the preparation of {alpha},{beta}-unsaturated carboxylic acids and esters thereof which comprises contacting formaldehyde or a source of formaldehyde with a carboxylic acid, ester or anhydride in the presence of a catalyst comprising an oxide of niobium.

  11. Adamantane dicarboxylic acid esters as possible additives to semisolid lubricants

    SciTech Connect

    Novikova, I.A.; Dolgopolova, T.N.; Apryatkin, A.D.

    1993-12-31

    The high efficiency of adamantane carboxylic acid esters as antiwear additives to lubricating compounds based on polysiloxane liquids has been demonstrated. Dibutyl and dihexyl esters of 5,7-dimethyl-1,3-adainantane dicarboxylic acid, increasing by several factors the efficiency of a semisolid lubricant based on liquid methyldichlorophenylsiloxane, have been synthesized and characterized.

  12. Improved preparation of haloalkyl bridged carboxylic ortho esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protection of a carboxylic acid function as a bridged ortho ester derivative enables the use of strong basic conditions in the synthetic strategy. For example, a protected 3-halopropionic acid can behave like an alkyl halide because the protons, alpha to the halide function, are less acidic. Ester...

  13. 40 CFR 721.2950 - Carboxylic acid glycidyl esters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Carboxylic acid glycidyl esters. 721... Substances § 721.2950 Carboxylic acid glycidyl esters. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as carboxylic acid glycidyl...

  14. 40 CFR 721.3110 - Polycarboxylic acid ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polycarboxylic acid ester (generic... Substances § 721.3110 Polycarboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polycarboxylic acid...

  15. 40 CFR 721.3110 - Polycarboxylic acid ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polycarboxylic acid ester (generic... Substances § 721.3110 Polycarboxylic acid ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a polycarboxylic acid...

  16. 40 CFR 721.3080 - Substituted phosphate ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Substituted phosphate ester (generic... Substances § 721.3080 Substituted phosphate ester (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted phosphate...

  17. 40 CFR 721.3080 - Substituted phosphate ester (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Substituted phosphate ester (generic... Substances § 721.3080 Substituted phosphate ester (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted phosphate...

  18. 40 CFR 721.3080 - Substituted phosphate ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Substituted phosphate ester (generic... Substances § 721.3080 Substituted phosphate ester (generic). (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as a substituted phosphate...

  19. Methods of refining and producing dibasic esters and acids from natural oil feedstocks

    DOEpatents

    Snead, Thomas E.; Cohen, Steven A.; Gildon, Demond L.

    2016-06-14

    Methods and systems for making dibasic esters and/or dibasic acids using metathesis are generally disclosed. In some embodiments, the methods comprise reacting a terminal olefin ester with an internal olefin ester in the presence of a metathesis catalyst to form a dibasic ester and/or dibasic acid. In some embodiments, the terminal olefin ester or the internal olefin ester are derived from a renewable feedstock, such as a natural oil feedstock. In some such embodiments, the natural oil feedstock, or a transesterified derivative thereof, is metathesized to make the terminal olefin ester or the internal olefin ester.

  20. Investigate the morphology and chemical properties of nanoengineered vinyl ester clay nanocomposite

    NASA Astrophysics Data System (ADS)

    Yebassa, Desta L.

    In recent years the area of nanocomposites has received considerable attention with the expectation that nanoclay filled polymers can be useful as matrix materials for composite applications. Although considerable progress has been made in understanding structure-property relationship of nanocomposites, consistent improvement in properties of nanocomposites remains elusive. This is because the addition of hydrophilic clay sheets to a hydrophobic polymeric resin can cause aggregation of clay sheets with and the aggregated clay sheets acting as stress concentration sites in the polymer matrix. The primary objective of this study was to improve the clay platelet separation in vinyl ester resin matrix by organically modifying the nanoclay platelet with a partially reactive onium salt. An approach to improving the compatibility of hydrophilic clay with the polymeric resin, is to chemically functionalize the clay with short and long chain cations, so as to increase the organophilicity of the clay surface layer and provide sufficient layer separation for polymer chains to infiltrate during curing. For our research purpose we selected medium and long chain length alkyl ammonium salts to functionalize clay. The medium chain length reactive onium salt (o-undecylenyl amine hydrochloride) was synthesized from commercial o-undecylenyl alcohol through a series of synthetic conversions which include bromination, azide formation, and azide reduction. The clay was ion exchanged with both reactive and non-reactive medium and long chain onium salts to form partially reactive clay. When the partially reactive clay and vinyl ester resin was sonicated with styrene, we obtained a variety of exfoliated/intercalated vinyl ester nanocomposite. Monomer styrene and high intensity ultrasonic mixing produces vinyl ester nanocomposite with the highest degree of clay platelet exfoliation. We also investigated the degradation of filled and unfilled polymer film exposed in alkali medium at various

  1. Ketone ester effects on metabolism and transcription

    PubMed Central

    Veech, Richard L.

    2014-01-01

    Ketosis induced by starvation or feeding a ketogenic diet has widespread and often contradictory effects due to the simultaneous elevation of both ketone bodies and free fatty acids. The elevation of ketone bodies increases the energy of ATP hydrolysis by reducing the mitochondrial NAD couple and oxidizing the coenzyme Q couple, thus increasing the redox span between site I and site II. In contrast, metabolism of fatty acids leads to a reduction of both mitochondrial NAD and mitochondrial coenzyme Q causing a decrease in the ΔG of ATP hydrolysis. In contrast, feeding ketone body esters leads to pure ketosis, unaccompanied by elevation of free fatty acids, producing a physiological state not previously seen in nature. The effects of pure ketosis on transcription and upon certain neurodegenerative diseases make approach not only interesting, but of potential therapeutic value. PMID:24714648

  2. Optimized Mechanical Behavior of Vinyl Ester Resins

    NASA Astrophysics Data System (ADS)

    Ganglani, Manisha; Torkelson, John; Carr, Stephen

    2001-03-01

    The cure (polymerization and solidification) of thermoset systems has been proposed also to involve phase separation in cases where the reactants are strongly heterogeneous. Vinyl ester (VE) resins are multi-component, thermosetting systems that are suspected of undergoing such phase separation during cure, and this work seeks to investigate this possibility and how it might affect mechanical behavior of the resulting solids. The autocatalytic equation is used to describe the cure kinetics of these systems, and it is found to work only at high levels of conversion. Mechanical behavior, as studied by tensile and fracture toughness tests, is correlated to initial cure conditions and the presence or absence of initiator and accelerator species; property optima have been established. No evidence was found for a second phase formed during polymerization, explaining why excellent physical properties are realized in these materials.

  3. Activated sludge degradation of adipic acid esters.

    PubMed Central

    Saeger, V W; Kalley, R G; Hicks, O; Tucker, E S; Mieure, J P

    1976-01-01

    The biodegradability of three aliphatic adipic acid diesters and a 1,3-butylene glycol adipic acid polyester was determined in acclimated, activated sludge systems. Rapid primary biodegradation from 67 to 99+% was observed at 3- and 13-mg/liter feed levels for di-n-hexyl adipate, di(2-ethylhexyl) adipate, and di(heptyl, nonyl) adipate in 24 h. When acclimated, activated sludge microorganisms were employed as the seed for two carbon dioxide evolution procedures, greater than 75% of the theoretical carbon dioxide was evolved for the three diesters and the polyester in a 35-day test period. The essentially complete biodegradation observed in these studies suggests that these esters would not persist when exposed to similar mixed microbial populations in the environment. PMID:1275494

  4. Phosphorylation of Kraft fibers with phosphate esters.

    PubMed

    Shi, Ying; Belosinschi, Dan; Brouillette, François; Belfkira, Ahmed; Chabot, Bruno

    2014-06-15

    Phosphate esters, derived from two different long-chain aliphatic alcohols, were used as phosphorylating reagents for Kraft pulp fibers. High phosphorus contents and almost non-degraded fibers were obtained by following this pathway. The phosphorylation efficiency was influenced by the alkyl chain length of PEs since the phosphorus content in modified fibers was higher for the shorter chain reagent. Due to the heterogeneous reaction environment, the amount of grafted phosphorus was found to be almost three times higher at the surface than in the bulk of the fibers. Analyses also indicated that the phosphorus was bonded to fibers as a phosphate-like structure. Furthermore, the situation seemed to be different for the fiber surface where significant amounts of phosphorus were present in more complex structures like pyrophosphate or even oligo-phosphate. PMID:24721058

  5. Catalytic Asymmetric Synthesis of Chiral Allylic Esters

    PubMed Central

    Cannon, Jeffrey S.; Kirsch, Stefan F.; Overman, Larry E.

    2010-01-01

    A broadly useful catalytic enantioselective synthesis of branched allylic esters from prochiral (Z)-2-alkene-1-ols has been developed. The starting allylic alcohol is converted to its trichloroacetimidate intermediate by reaction with trichloroacetonitrile, either in situ or in a separate step, and this intermediate undergoes clean enantioselective SN2′ substitution with a variety of carboxylic acids in the presence of the palladium(II) catalyst (Rp,S)-di-μ -acetatobis[(η5-2-(2'-(4'-methylethyl)oxazolinyl)cyclopentadienyl,1-C,3'-N)(η4-tetraphenylcyclobutadiene)cobalt]dipalladium, (Rp,S)-[COP-OAc]2 or its enantiomer. The scope and limitations of this useful catalytic asymmetric allylic esterification are defined. PMID:15740118

  6. Biodegradation of the phthalates and their esters by bacteria.

    PubMed Central

    Keyser, P; Pujar, B G; Eaton, R W; Ribbons, D W

    1976-01-01

    Recent studies on the biodegradation phthalate esters in natural ecosystems, sewage, and laboratory cultures are reviewed. There is ample evidence to demonstrate that bacteria are major elements in the biodegradative processes and that in most situations complete oxidation of the aromatic ring occurs; much less is known about the catabolism of the alcoholic moiety, e.g., 2-ethylhexanol. Evidence is presented to support catabolic pathways in pseudomonads and micrococci that are initiated by successive hydrolyses of the diesters to give the phthalate anion. Thereafter a dioxygenase catalyzes the formation of 4,5-dihydro-4,5-dihydroxyphthalate, which is oxidized by an NAD-dependent dehydrogenase to give 4,5-dihydroxyphthalate, Protocatechuate, formed by decarboxylation of 4,5-dihydroxyphthalate, is the substrate for ring cleavage enzymes. Whereas flurorescent pseudomonads use the beta-ketoadipate pathway, the nonfluorescent strains and micrococci examined use of meta-cleavage (4,5-) route. All the intermediates proposed have been accumulated by enzymes purified from Pseudomonas fluorescens. Isophthalate and terephthalate (anions) are readily used as carbon sources by aerobic bacteria, and preliminary evidence is consistent with catabolic routes for these isomers converging at the ring-cleavage substrate protocatechuate. Some possible effects and interactions of synthetic organic chemicals with the natural microflora, and the influence of other vectors, is discussed in relation to the maintenance of the carbon cycle and environmental pollution. PMID:829485

  7. Functional expression and characterization of five wax ester synthases in Saccharomyces cerevisiae and their utility for biodiesel production

    PubMed Central

    2012-01-01

    Background Wax ester synthases (WSs) can synthesize wax esters from alcohols and fatty acyl coenzyme A thioesters. The knowledge of the preferred substrates for each WS allows the use of yeast cells for the production of wax esters that are high-value materials and can be used in a variety of industrial applications. The products of WSs include fatty acid ethyl esters, which can be directly used as biodiesel. Results Here, heterologous WSs derived from five different organisms were successfully expressed and evaluated for their substrate preference in Saccharomyces cerevisiae. We investigated the potential of the different WSs for biodiesel (that is, fatty acid ethyl esters) production in S. cerevisiae. All investigated WSs, from Acinetobacter baylyi ADP1, Marinobacter hydrocarbonoclasticus DSM 8798, Rhodococcus opacus PD630, Mus musculus C57BL/6 and Psychrobacter arcticus 273-4, have different substrate specificities, but they can all lead to the formation of biodiesel. The best biodiesel producing strain was found to be the one expressing WS from M. hydrocarbonoclasticus DSM 8798 that resulted in a biodiesel titer of 6.3 mg/L. To further enhance biodiesel production, acetyl coenzyme A carboxylase was up-regulated, which resulted in a 30% increase in biodiesel production. Conclusions Five WSs from different species were functionally expressed and their substrate preference characterized in S. cerevisiae, thus constructing cell factories for the production of specific kinds of wax ester. WS from M. hydrocarbonoclasticus showed the highest preference for ethanol compared to the other WSs, and could permit the engineered S. cerevisiae to produce biodiesel. PMID:22364438

  8. Statistical Evaluation of HTS Assays for Enzymatic Hydrolysis of β-Keto Esters

    PubMed Central

    Dold, S. -M.; Zimmermann, S.; Hamacher, K.; Schmitz, K.; Rudat, J.

    2016-01-01

    β-keto esters are used as precursors for the synthesis of β-amino acids, which are building blocks for some classes of pharmaceuticals. Here we describe the comparison of screening procedures for hydrolases to be used for the hydrolysis of β-keto esters, the first step in the preparation of β-amino acids. Two of the tested high throughput screening (HTS) assays depend on coupled enzymatic reactions which detect the alcohol released during ester hydrolysis by luminescence or absorption. The third assay detects the pH shift due to acid formation using an indicator dye. To choose the most efficient approach for screening, we assessed these assays with different statistical methods—namely, the classical Z’-factor, standardized mean difference (SSMD), the Kolmogorov-Smirnov-test, and t-statistics. This revealed that all three assays are suitable for HTS, the pH assay performing best. Based on our data we discuss the explanatory power of different statistical measures. Finally, we successfully employed the pH assay to identify a very fast hydrolase in an enzyme-substrate screening. PMID:26730596

  9. Statistical Evaluation of HTS Assays for Enzymatic Hydrolysis of β-Keto Esters.

    PubMed

    Buß, O; Jager, S; Dold, S-M; Zimmermann, S; Hamacher, K; Schmitz, K; Rudat, J

    2016-01-01

    β-keto esters are used as precursors for the synthesis of β-amino acids, which are building blocks for some classes of pharmaceuticals. Here we describe the comparison of screening procedures for hydrolases to be used for the hydrolysis of β-keto esters, the first step in the preparation of β-amino acids. Two of the tested high throughput screening (HTS) assays depend on coupled enzymatic reactions which detect the alcohol released during ester hydrolysis by luminescence or absorption. The third assay detects the pH shift due to acid formation using an indicator dye. To choose the most efficient approach for screening, we assessed these assays with different statistical methods-namely, the classical Z'-factor, standardized mean difference (SSMD), the Kolmogorov-Smirnov-test, and t-statistics. This revealed that all three assays are suitable for HTS, the pH assay performing best. Based on our data we discuss the explanatory power of different statistical measures. Finally, we successfully employed the pH assay to identify a very fast hydrolase in an enzyme-substrate screening. PMID:26730596

  10. Novel FT-IR Microspectroscopic Census of Simple Starch Granules for Octenyl Succinate Ester Modification

    SciTech Connect

    Bai, Y.; Shi, Y; Wetzel, D

    2009-01-01

    Fourier transform infrared (FT-IR) microspectroscopy was used to investigate reaction homogeneity of octenyl succinic anhydride modification on waxy maize starch and detect uniformity of blends of modified and native starches. For the first time, the level and uniformity of chemical substitution on individual starch granules were analyzed by FT-IR microspectroscopy. More than 100 starch granules of each sample were analyzed one by one by FT-IR microspectroscopy. In comparison to the native starch, modified starch had two additional bands at 1723 and 1563 cm{sup -1}, indicative of ester formation in the modified starch. For the 3% modification level, the degree of substitution (DS) was low (0.019) and the distribution of the ester group was not uniform among starch granules. For the modified starch with DS of 0.073, 99% of individual starch granules had a large carbonyl band area, indicating that most granules were modified to a sufficient extent that the presence of their carbonyl ester classified them individually as being modified. However, the octenyl succinate concentration varied between granules, suggesting that the reaction was not uniform. When modified starch (DS = 0.073) was blended with native starch (3:7, w/w) to achieve a mixture with an average DS of 0.019, FT-IR microspectroscopy was able to detect heterogeneity of octenyl succinate in the blend and determine the ratio of the modified starch to the native starch granules.

  11. Ruthenium(II)-PNN pincer complex catalyzed dehydrogenation of benzyl alcohol to ester: A DFT study

    NASA Astrophysics Data System (ADS)

    Tao, Jingcong; Wen, Li; Lv, Xiaobo; Qi, Yong; Yin, Hailiang

    2016-04-01

    The molecular mechanism of the dehydrogenation of primary alcohol to ester catalyzed by the ruthenium(II)-PNN pincer complex Ru(H)(η2-BH4)(PNN), [PNN: (2-(di-tert-butylphosphinomethyl)-6-(diethlaminomethyl)-pyridine)] has been investigated using density functional theory calculations. The catalytic cycle includes three stages: (stage I) alcohol dehydrogenation to form aldehyde, (stage II) coupling of aldehyde with alcohol to give hemiacetal or ester, and (stage III) hemiacetal dehydrogenation to form ester. Two dehydrogenation reactions occur via the β-H elimination mechanism rather than the bifunctional double hydrogen transfer mechanism, which could be rationalized as the fluxional behavior of the BH4- ligand. At the second stage, the coupling reaction requires alcohol or the ruthenium catalyst as mediator. The formation of hemiacetal through the alcohol-mediated pathway is kinetically favorable than the ruthenium catalyst-mediated one, which may be attributed to the smaller steric hindrance when the aldehyde approaches the alcohol moiety in the reaction system. Our results would be helpful for experimental chemists to design more effective transition metal catalysts for dehydrogenation of alcohols.

  12. The Glutathione Derivative, GSH Monoethyl Ester, May Effectively Whiten Skin but GSH Does Not

    PubMed Central

    Chung, Bo Young; Choi, So Ra; Moon, Ik Jun; Park, Chun Wook; Kim, Young-Hoon; Chang, Sung Eun

    2016-01-01

    Glutathione in its reduced form (GSH) is an antioxidant and also is involved in pheomelanin formation. Thus, it has been long believed that GSH has a skin whitening effect. However, its actual or direct effect is unproven. We evaluated the anti-melanogenic effects of GSH and its derivatives in vitro. We examined change of melanogenesis and its related proteins by GSH itself and its derivatives, including GSH monoethyl ester (GSH-MEE), GSH diethyl ester (GSH-DEE) and GSH monoisopropyl ester (GSH-MIPE) in Melan-A cells, Mel-Ab cells, and B16F10 cells. GSH and GSH-MEE did not display cytotoxic activity, but GSH-MIPE and GSH-DEE did. Intriguingly, GSH itself had no inhibitory effect on melanin production or intracellular tyrosinase activity. Rather, it was GSH-MEE and GSH-MIPE that profoundly reduced the amount of melanin and intracellular tyrosinase activity. Thus, GSH-MEE was selected as a suitable candidate skin-whitening agent and it did not alter melanogenesis-associated proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2, but it did increase the amount of suggested pheomelanin and suggested pheomelanin/eumelanin ratio. GSH-MEE was effective for anti-melanogenesis, whereas GSH itself was not. GSH-MEE could be developed as a safe and efficient agent for the treatment of hyperpigmentation skin disorders. PMID:27128906

  13. The Glutathione Derivative, GSH Monoethyl Ester, May Effectively Whiten Skin but GSH Does Not.

    PubMed

    Chung, Bo Young; Choi, So Ra; Moon, Ik Jun; Park, Chun Wook; Kim, Young-Hoon; Chang, Sung Eun

    2016-01-01

    Glutathione in its reduced form (GSH) is an antioxidant and also is involved in pheomelanin formation. Thus, it has been long believed that GSH has a skin whitening effect. However, its actual or direct effect is unproven. We evaluated the anti-melanogenic effects of GSH and its derivatives in vitro. We examined change of melanogenesis and its related proteins by GSH itself and its derivatives, including GSH monoethyl ester (GSH-MEE), GSH diethyl ester (GSH-DEE) and GSH monoisopropyl ester (GSH-MIPE) in Melan-A cells, Mel-Ab cells, and B16F10 cells. GSH and GSH-MEE did not display cytotoxic activity, but GSH-MIPE and GSH-DEE did. Intriguingly, GSH itself had no inhibitory effect on melanin production or intracellular tyrosinase activity. Rather, it was GSH-MEE and GSH-MIPE that profoundly reduced the amount of melanin and intracellular tyrosinase activity. Thus, GSH-MEE was selected as a suitable candidate skin-whitening agent and it did not alter melanogenesis-associated proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2, but it did increase the amount of suggested pheomelanin and suggested pheomelanin/eumelanin ratio. GSH-MEE was effective for anti-melanogenesis, whereas GSH itself was not. GSH-MEE could be developed as a safe and efficient agent for the treatment of hyperpigmentation skin disorders. PMID:27128906

  14. The phase behavior of cholesteryl esters in intracellular inclusions.

    PubMed

    Snow, J W; Glick, J M; Phillips, M C

    1992-09-15

    Differential scanning calorimetry and polarizing light microscopy have been used to investigate kinetic and thermodynamic properties of the phase behavior of cholesteryl ester contained in Fu5AH rat hepatoma cells and J774 murine macrophages. These cultured cells store cholesteryl esters as cytoplasmic inclusions of approximately 1-micron diameter and thus are models of the foam cells characteristic of atherosclerotic plaque. Simple binary mixtures of cholesteryl palmitate and cholesteryl oleate, the predominant cholesteryl esters in cellular inclusions in both cell types serve as models to explain important aspects of the phase behavior of these inclusions. Although inclusions should exist as stable crystals at 37 degrees C under conditions of thermodynamic equilibrium, microscopic examination of cells indicates that inclusions exist as metastable liquid crystals at 37 degrees C for extended periods of time. Using an analytical model based on nucleation theory, we predict that the cholesteryl ester inclusions should be liquid-crystalline in the cytoplasm of living cells. This may not be true either for lysosomal cholesteryl ester or for extracellular cholesteryl ester present in advanced atherosclerotic plaque where fusion of droplets can enhance the possibility of crystallization. The enhanced metastability of the relatively fluid liquid-crystalline state in cellular inclusions should result in increased activity of the neutral cholesteryl ester hydrolase in living cells. PMID:1326528

  15. Short-chain aliphatic ester synthesis using Thermobifida fusca cutinase.

    PubMed

    Su, Lingqia; Hong, Ruoyu; Guo, Xiaojie; Wu, Jing; Xia, Yongmei

    2016-09-01

    Short-chain aliphatic esters are commonly used as fruit flavorings in the food industry. In this study, Thermobifida fusca (T. fusca) cutinase was used for the synthesis of aliphatic esters, and the maximum yield of ethyl caproate reached 99.2% at a cutinase concentration of 50U/ml, 40°C, and water content of 0.5%, representing the highest ester yield to date. The cutinase-catalyzed esterification displayed strong tolerance for water content (up to 8%) and acid concentration (up to 0.8M). At substrate concentrations ⩽0.8M, the ester yield remained above 80%. Moreover, ester yields of more than 98% and 95% were achieved for acids of C3-C8 and alcohols of C1-C6, respectively, indicating extensive chain length selectivity of the cutinase. These results demonstrate the superior ability of T. fusca cutinase to catalyze the synthesis of short-chain esters. This study provides the basis for industrial production of short-chain esters using T. fusca cutinase. PMID:27041308

  16. Metabolic pathway engineering for fatty acid ethyl ester production in Saccharomyces cerevisiae using stable chromosomal integration.

    PubMed

    de Jong, Bouke Wim; Shi, Shuobo; Valle-Rodríguez, Juan Octavio; Siewers, Verena; Nielsen, Jens

    2015-03-01

    Fatty acid ethyl esters are fatty acid derived molecules similar to first generation biodiesel (fatty acid methyl esters; FAMEs) which can be produced in a microbial cell factory. Saccharomyces cerevisiae is a suitable candidate for microbial large scale and long term cultivations, which is the typical industrial production setting for biofuels. It is crucial to conserve the metabolic design of the cell factory during industrial cultivation conditions that require extensive propagation. Genetic modifications therefore have to be introduced in a stable manner. Here, several metabolic engineering strategies for improved production of fatty acid ethyl esters in S. cerevisiae were combined and the genes were stably expressed from the organisms' chromosomes. A wax ester synthase (ws2) was expressed in different yeast strains with an engineered acetyl-CoA and fatty acid metabolism. Thus, we compared expression of ws2 with and without overexpression of alcohol dehydrogenase (ADH2), acetaldehyde dehydrogenase (ALD6) and acetyl-CoA synthetase (acs SE (L641P) ) and further evaluated additional overexpression of a mutant version of acetyl-CoA decarboxylase (ACC1 (S1157A,S659A) ) and the acyl-CoA binding protein (ACB1). The combined engineering efforts of the implementation of ws2, ADH2, ALD6 and acs SE (L641P) , ACC1 (S1157A,S659A) and ACB1 in a S. cerevisiae strain lacking storage lipid formation (are1Δ, are2Δ, dga1Δ and lro1Δ) and β-oxidation (pox1Δ) resulted in a 4.1-fold improvement compared with sole expression of ws2 in S. cerevisiae. PMID:25422103

  17. Distillative self-sorting of dynamic ester libraries.

    PubMed

    Ji, Qing; Miljanić, Ognjen Š

    2013-12-20

    Metal alkoxides, such as NaOt-Bu or Ti(OBu)4, can initiate acyl exchange within complex ester libraries. Reactive distillation of such dynamic combinatorial libraries (DCLs) isolates the most volatile ester at the expense of the less volatile library members that share a constituent with it. This process can be iteratively repeated to yield up to four industrially relevant esters as pure products from a single reaction setup. An algorithm has been developed to predict reactive distillation products in DCLs of as many as 121 members. PMID:24245808

  18. Effects of phorbol esters in carp (Cyprinus carpio L).

    PubMed

    Becker, K; Makkar, H P

    1998-04-01

    Carp (Cyprinus carpio L) were fed diets containing phorbol esters at concentrations of 0, 3.75, 7.5, 15, 31, 62.5, 125, 250, 500 and 1,000 micrograms/g feed. Phorbol esters were from Jatropha curcas nuts. Jatropha curcas toxicity has been reported in humans, rodents and livestock, and phorbol esters have been identified as the main toxic agent. The adverse effects observed in carp at phorbol esters concentrations of 31 micrograms/g or higher were lower average metabolic growth rate, fecal mucus production and rejection of feed. Average metabolic growth rates (g/kg 0.8/d) in a 7-d experimental period during which diets containing phorbol esters were fed to carp (values with different letters being significantly different) were 15.4a, 14.4a, 12.5ab, 12.4ab, 10.9b, 3.4c, 0.2c, -3.8d, -4.9d and -5.6d, respectively, at the above mentioned concentrations. The values for the recovery phase of 9-d during which phorbol esters were not included in the diet were 16.0a, 15.6a, 14.9a, 15.6a, 5.3b, 1.6b, 4.6bc, 6.3bc, 7.8c and 8.2c, respectively. The adverse effects of phorbol esters were reversible since withdrawal of the esters from the diets led to gain in body mass. None of the fish died at any of the concentrations studied. Incorporation of vitamin C, an antioxidant, at levels of 0.4 and 2% in the feed did not prevent occurrence of the adverse effects of the phorbol esters. The threshold level at which phorbol esters appeared to cause adverse effects in carp was 15 micrograms/g feed or 15 ppm in the diet. Carp were highly sensitive to phorbol esters, thus making them a useful species for bioassay of these compounds. This bioassay together with other analytic procedures could be of immense use in the development of detoxification processes for agro-industrial products containing phorbol esters, such as jatropha meal or jatropha oil, and as a quality control method to monitor successive stages in industrial detoxification processes. PMID:9554059

  19. Liberation of sulfate from sulfate esters by soils.

    PubMed Central

    Houghton, C; Rose, R A

    1976-01-01

    When incubated with acid, alkaline, and neutral soils, a variety of synthetic sulfate esters representing the various classes of these compounds was hydrolyzed by enzymes, probably of microbial origin. The appearance of sulfate in the soil water occurred immediately after introduction into the soils with some esters, whereas with others it occurred only after lag periods. Heat treatment destroyed the hydrolytic acitivity in the soils. The ester sulfate groups present in humic acid extracted from the soil appeared to be resistant to hydrolysis by a variety of sulfohydrolases extracted from bacteria and other organisms. Images PMID:938044

  20. An efficient Pd-catalyzed route to silyl esters

    PubMed

    Chauhan; Chauhan; Boudjouk

    2000-04-20

    [formula: see text] A one-step, highly selective catalytic route to silyl esters is reported. Commercially available silanes with Si-H functionality were converted to silyl or siloxy esters in the presence of Pd(OAc)2 under mild reaction conditions. This protocol was found to be equally applicable for the modification of multiple silicon centers in one framework and lead to the corresponding polysilyl esters in high yields. A comparison of catalytic efficiency of Pd(OAc)2 versus Pd on carbon was also undertaken. PMID:10804545

  1. Molecular dynamics simulations of neat vinyl ester and vapor-grown carbon nanofiber/vinyl ester resin composites

    NASA Astrophysics Data System (ADS)

    Jang, Changwoon

    Molecular dynamics (MD) simulations have been performed to investigate the system equilibrium through the atomic/molecular interactions of a liquid vinyl ester (VE) thermoset resin with the idealized surfaces of both pristine vapor-grown carbon nanofibers (VGCNFs) and oxidized VGCNFs. The VE resin has a mole ratio of styrene to bisphenol-A-diglycidyl dimethacrylate VE monomers consistent with a commercially available 33 wt% styrene VE resin (Derakane 441-400). The VGCNF-VE resin interactions may influence the distribution of the liquid VE monomers in the system and the formation of an interphase region. Such an interphase may possess a different mole ratio of VE resin monomers at the vicinity of the VGCNF surfaces compared to the rest of the system after resin curing. Bulk nano-reinforced material properties are highly dependent on the interphase features because of the high surface area to volume ratio of nano-reinforcements. For example, higher length scale micromechanical calculations suggest that the volume fraction and properties of the interphase can have a profound effect on bulk material properties. Interphase formation, microstructure, geometries, and properties in VGCNF-reinforced polymeric composites have not been well characterized experimentally, largely due to the small size of typical nano-reinforcements and interphases. Therefore, MD simulations offer an alternative means to probe the nano-sized formation of the interphase and to determine its properties, without having to perform fine-scale experiments. A robust crosslinking algorithm for VE resin was then developed as a key element of this research. VE resins are crosslinked via free radical copolymerization account for regioselectivity and monomer reactivity ratios. After the VE crosslinked network was created, the constitutive properties of the resin were calculated. This algorithm will be used to crosslink equilibrated VE resin systems containing both pristine and oxidized VGCNFs. An

  2. Chan-Evans-Lam Amination of Boronic Acid Pinacol (BPin) Esters: Overcoming the Aryl Amine Problem.

    PubMed

    Vantourout, Julien C; Law, Robert P; Isidro-Llobet, Albert; Atkinson, Stephen J; Watson, Allan J B

    2016-05-01

    The Chan-Evans-Lam reaction is a valuable C-N bond forming process. However, aryl boronic acid pinacol (BPin) ester reagents can be difficult coupling partners that often deliver low yields, in particular in reactions with aryl amines. Herein, we report effective reaction conditions for the Chan-Evans-Lam amination of aryl BPin with alkyl and aryl amines. A mixed MeCN/EtOH solvent system was found to enable effective C-N bond formation using aryl amines while EtOH is not required for the coupling of alkyl amines. PMID:27045570

  3. A Detailed Chemical Kinetic Reaction Mechanism for Oxidation of Four Small Alkyl Esters in Laminar Premixed Flames

    SciTech Connect

    Westbrook, C K; Pitz, W J; Westmoreland, P R; Dryer, F L; Chaos, M; Osswald, P; Kohse-Hoinghaus, K; Cool, T A; Wang, J; Yang, B; Hansen, N; Kasper, T

    2008-02-08

    A detailed chemical kinetic reaction mechanism has been developed for a group of four small alkyl ester fuels, consisting of methyl formate, methyl acetate, ethyl formate and ethyl acetate. This mechanism is validated by comparisons between computed results and recently measured intermediate species mole fractions in fuel-rich, low pressure, premixed laminar flames. The model development employs a principle of similarity of functional groups in constraining the H atom abstraction and unimolecular decomposition reactions in each of these fuels. As a result, the reaction mechanism and formalism for mechanism development are suitable for extension to larger oxygenated hydrocarbon fuels, together with an improved kinetic understanding of the structure and chemical kinetics of alkyl ester fuels that can be extended to biodiesel fuels. Variations in concentrations of intermediate species levels in these flames are traced to differences in the molecular structure of the fuel molecules.

  4. Synthesis and low temperature characterization of iso-oleic ester derivatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three new iso-oleic ester derivatives (i.e., isopropyl esters (IOA-iPrE), n-butyl esters (IOA-n-BuE), and 2-ethylhexyl esters (IOA-2-EHE)) were synthesized from iso-oleic acid (IOA) using a standard esterification method. These esterified alcohols were chosen because of their bulky and branched-cha...

  5. Analysis of phosphate esters in plant material

    PubMed Central

    Isherwood, F. A.; Barrett, F. C.

    1967-01-01

    1. A critical study was made of the quantitative extraction of nucleotide and sugar phosphates from plant tissue by either boiling aqueous ethanol or cold trichloroacetic acid. The effect of the extraction technique on the inactivation of the enzymes in the plant tissue and the possibility of adsorption of the phosphate esters on the cell wall were especially considered. 2. In the recommended method the plant tissue was frozen in liquid nitrogen, ground to a powder and then blended with cold aqueous trichloroacetic acid containing 8-hydroxyquinoline to prevent adsorption. 3. The extract contained large amounts of trichloroacetic acid, cations, chloride, sugars, amino acids, hydroxy organic acids, phytic acid, orthophosphoric acid and high-molecular-weight material including some phosphorus-containing compounds. All of these were removed as they were liable to interfere with the chromatographic or enzymic assay of the individual nucleotide or sugar phosphates. 4. The procedure was as follows: the last traces of trichloroacetic acid were extracted with ether after the solution had been passed through a column of Dowex AG 50 in the hydrogen form to remove all cations. High-molecular-weight compounds were removed by ultrafiltration and low-molecular-weight solutes by a two-stage chromatography on cellulose columns with organic solvents. In the first stage, sugars, amino acids, chloride and phytic acid were separated by using a basic solvent (propan-1-ol–water–aqueous ammonia) and, in the second stage, the organic acids and orthophosphoric acid were separated by using an acidic solvent (di-isopropyl ether–formic acid–2-methylpropan-2-ol–water). The final solution of nucleotide and sugar phosphates was substantially free from other solutes and was suitable for the detection of individual phosphate esters by either chromatography or enzymic assay. 5. The recovery of d-glucose 6-phosphate or adenosine 5′-triphosphate added to a trichloroacetic acid extract

  6. Structure-activity correlations for organophosphorus ester anticholinesterases. Part 2: CNDO/2 calculations applied to ester hydrolysis rates

    NASA Technical Reports Server (NTRS)

    Johnson, H.; Kenley, R. A.; Rynard, C.; Golub, M. A.

    1984-01-01

    Quantitative structure-activity relationships are presented for the hydrolysis of organophosphorus esters, RR'P(O)X, where R and R' are alkyl and/or alkoxy groups and X is fluorine, chlorine or a phenoxy group. CNDO/2 calculations provide values for molecular parameters that correlate with alkaline hydrolysis rates. For each subset of esters with the same leaving group, X, the CNDO-derived net atomic charge at the central phosphorus atom correlates well with the alkaline hydrolysis rate constants. For the whole set of esters with different leaving groups, equations are derived that relate charge, orbital energy and bond order to the hydrolysis rate constants.

  7. Branched Fatty Acid Esters of Hydroxy Fatty Acids Are Preferred Substrates of the MODY8 Protein Carboxyl Ester Lipase.

    PubMed

    Kolar, Matthew J; Kamat, Siddhesh S; Parsons, William H; Homan, Edwin A; Maher, Tim; Peroni, Odile D; Syed, Ismail; Fjeld, Karianne; Molven, Anders; Kahn, Barbara B; Cravatt, Benjamin F; Saghatelian, Alan

    2016-08-23

    A recently discovered class of endogenous mammalian lipids, branched fatty acid esters of hydroxy fatty acids (FAHFAs), possesses anti-diabetic and anti-inflammatory activities. Here, we identified and validated carboxyl ester lipase (CEL), a pancreatic enzyme hydrolyzing cholesteryl esters and other dietary lipids, as a FAHFA hydrolase. Variants of CEL have been linked to maturity-onset diabetes of the young, type 8 (MODY8), and to chronic pancreatitis. We tested the FAHFA hydrolysis activity of the CEL MODY8 variant and found a modest increase in activity as compared with that of the normal enzyme. Together, the data suggest that CEL might break down dietary FAHFAs. PMID:27509211

  8. Consecutive visible-light photoredox decarboxylative couplings of adipic acid active esters with alkynyl sulfones leading to cyclic compounds.

    PubMed

    Li, Jingjing; Tian, Hua; Jiang, Min; Yang, Haijun; Zhao, Yufen; Fu, Hua

    2016-07-01

    Novel and efficient consecutive photoredox decarboxylative couplings of adipic acid active esters (bis(1,3-dioxoisoindolin-2-yl)-substituted hexanedioates) with substituted 1-(2-arylethynylsulfonyl)benzenes have been developed under visible-light photocatalysis. The successive photoredox decarboxylative C-C bond formation at room temperature afforded the corresponding cyclic compounds in good yields with tolerance of some functional groups. PMID:27345832

  9. Automated library synthesis of cyclopropyl boronic esters employing diazomethane in a tube-in-tube flow reactor.

    PubMed

    Koolman, Hannes F; Kantor, Stanislaw; Bogdan, Andrew R; Wang, Ying; Pan, Jeffrey Y; Djuric, Stevan W

    2016-07-01

    The efficient synthesis of cyclopropyl boronic esters in library format using a diazomethane flow reactor has been achieved. A pivotal component of the system is a fully automated tube-in-tube reactor allowing for safe handling of hazardous diazomethane on repeated small scale and for the generation of larger quantities of product. The setup enables the repeated execution of Pd-catalyzed cyclopropanation reactions without compromising its operation over time. PMID:27314279

  10. Methods of refining and producing dibasic esters and acids from natural oil feedstocks

    DOEpatents

    Snead, Thomas E.; Cohen, Steven A.; Gildon, Demond L.

    2016-03-15

    Methods are provided for refining natural oil feedstocks and producing dibasic esters and/or dibasic acids. The methods comprise reacting a terminal olefin with an internal olefin in the presence of a metathesis catalyst to form a dibasic ester and/or dibasic acid. In certain embodiments, the olefin esters are formed by reacting the feedstock in the presence of a metathesis catalyst under conditions sufficient to form a metathesized product comprising olefins and esters, separating the olefins from the esters in the metathesized product, and transesterifying the esters in the presence of an alcohol to form a transesterified product having olefin esters.

  11. Methods of refining and producing dibasic esters and acids from natural oil feedstocks

    SciTech Connect

    Snead, Thomas E; Cohen, Steven A; Gildon, Demond L

    2015-04-07

    Methods are provided for refining natural oil feedstocks and producing dibasic esters and/or dibasic acids. The methods comprise reacting a terminal olefin with an internal olefin in the presence of a metathesis catalyst to form a dibasic ester and/or dibasic acid. In certain embodiments, the olefin esters are formed by reacting the feedstock in the presence of a metathesis catalyst under conditions sufficient to form a metathesized product comprising olefins and esters, separating the olefins from the esters in the metathesized product, and transesterifying the esters in the presence of an alcohol to form a transesterified product having olefin esters.

  12. Decarbonylative organoboron cross-coupling of esters by nickel catalysis.

    PubMed

    Muto, Kei; Yamaguchi, Junichiro; Musaev, Djamaladdin G; Itami, Kenichiro

    2015-01-01

    The Suzuki-Miyaura cross-coupling is a metal-catalysed reaction in which boron-based nucleophiles and halide-based electrophiles are reacted to form a single molecule. This is one of the most reliable tools in synthetic chemistry, and is extensively used in the synthesis of pharmaceuticals, agrochemicals and organic materials. Herein, we report a significant advance in the choice of electrophilic coupling partner in this reaction. With a user-friendly and inexpensive nickel catalyst, a range of phenyl esters of aromatic, heteroaromatic and aliphatic carboxylic acids react with boronic acids in a decarbonylative manner. Overall, phenyl ester moieties function as leaving groups. Theoretical calculations uncovered key mechanistic features of this unusual decarbonylative coupling. Since extraordinary numbers of ester-containing molecules are available both commercially and synthetically, this new 'ester' cross-coupling should find significant use in synthetic chemistry as an alternative to the standard halide-based Suzuki-Miyaura coupling. PMID:26118733

  13. Enzymatic synthesis of oligo- and polysaccharide fatty acid esters.

    PubMed

    van den Broek, Lambertus A M; Boeriu, Carmen G

    2013-03-01

    Amphiphilic oligo- and polysaccharides (e.g. polysaccharide alkyl or alkyl-aryl esters) form a new class of polymers with exceptional properties. They function as polymeric surfactants, whilst maintaining most of the properties of the starting polymeric material such as emulsifying, gelling, and film forming properties combined with partial water solubility or permeability. At present carbohydrate fatty acid esters are generally obtained by chemical methods using toxic solvents and organic and inorganic catalysts that leave residual traces in the final products. Enzymatic reactions offer an attractive alternative route for the synthesis of polysaccharide esters. In this review the state of the art of enzymatic synthesis of oligo- and polysaccharides fatty esters has been described. PMID:23465902

  14. 21 CFR 172.854 - Polyglycerol esters of fatty acids.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Polyglycerol esters of a mixture of stearic, oleic, and coconut fatty acids are used as a cloud inhibitor in... used at a level not in excess of the amount required to perform its cloud-inhibiting effect. Oleic...

  15. Decarbonylative organoboron cross-coupling of esters by nickel catalysis

    PubMed Central

    Muto, Kei; Yamaguchi, Junichiro; Musaev, Djamaladdin G.; Itami, Kenichiro

    2015-01-01

    The Suzuki–Miyaura cross-coupling is a metal-catalysed reaction in which boron-based nucleophiles and halide-based electrophiles are reacted to form a single molecule. This is one of the most reliable tools in synthetic chemistry, and is extensively used in the synthesis of pharmaceuticals, agrochemicals and organic materials. Herein, we report a significant advance in the choice of electrophilic coupling partner in this reaction. With a user-friendly and inexpensive nickel catalyst, a range of phenyl esters of aromatic, heteroaromatic and aliphatic carboxylic acids react with boronic acids in a decarbonylative manner. Overall, phenyl ester moieties function as leaving groups. Theoretical calculations uncovered key mechanistic features of this unusual decarbonylative coupling. Since extraordinary numbers of ester-containing molecules are available both commercially and synthetically, this new ‘ester' cross-coupling should find significant use in synthetic chemistry as an alternative to the standard halide-based Suzuki–Miyaura coupling. PMID:26118733

  16. ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS

    EPA Science Inventory

    SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external...

  17. ESTIMATION OF PHOSPHATE ESTER HYDROLYSIS RATE CONSTANTS. I. ALKALINE HYDROLYSIS

    EPA Science Inventory

    SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition state...

  18. ESTIMATION OF PHOSPHATE ESTER HYDROLYSIS RATE CONSTANTS - ALKALINE HYDROLYSIS

    EPA Science Inventory

    SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition state...

  19. Epoxy resin composition containing metal tetrafluoroborate and boron ester

    SciTech Connect

    Morehead, G.T.

    1990-06-12

    This patent describes a curable composition. It comprises: a polyepoxide; a metal tetrafluoroborate; and at least one boron ester selected from the group consisting of triesters of boric acid and diesters of boronic acid.

  20. Alternating Poly(ester-anhydride) by Insertion Polycondensation.

    PubMed

    Haim-Zada, Moran; Basu, Arijit; Hagigit, Tal; Schlinger, Ron; Grishko, Michael; Kraminsky, Alexander; Hanuka, Ezra; Domb, Abraham J

    2016-06-13

    We report on a synthetic method where polyanhydride is used as starting material and the ester monomers are inserted through complete esterification, leading to an alternating ester-anhydride copolymer. The molar ratio of ricinoleic acid (RA) and sebacic acid (SA) was optimized until polysebacic acid is completely converted to carboxylic acid-terminated RA-SA and RA-SA-RA ester-dicarboxylic acids. These dimers and trimers were activated with acetic anhydride, polymerized under heat and vacuum to yield alternating RA-SA copolymer. The resulting alternating poly(ester-anhydride) have the RA at regular intervals. The regular occurrences of RA side chains prevent anhydride interchange, enhancing hydrolytic stability, which allows storage of the polymer at room temperature. PMID:27198864

  1. Synthesis and evaluation of oleic acid esters as dielectric liquids

    SciTech Connect

    Thomas, P.; Sridhar, S.; Krishnaswamy, K.R.

    1996-12-31

    The worldwide depletion of petroleum crude and the search for technologically and ecologically alternative to PCB`s has led to the development of synthetic liquid dielectric which are non-flammable, non-toxic and bio-degradable. Esters like Methyl oleate and Pentaerthritol tetra oleate were synthesized in the laboratory. These esters were evaluated for its Physical, Chemical, Electrical and Aging properties and the values obtained compare well with those of commercially available liquids like Midel 7131 and RTemp fluid. Further accelerated aging studies were performed on these esters and the data obtained reveal that the esters prepared in the laboratory has very good chemical stability towards oxidation without inhibitor when compared to Midel 7131 and RTemp fluid which have phenolic inhibitors.

  2. Incorporation of Epicatechin Esters into Lignin Enhances Cell Wall Fermentability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenolic catechin esters are potentially attractive targets for lignin bioengineering because their copolymerization with monolignols could reduce lignin hydrophobicity and cross-linking to polysaccharides, or facilitate delignification by biomass pretreatments. To test this hypothesis, we biomi...

  3. Synthesis of ethers from esters via Fe-catalyzed hydrosilylation.

    PubMed

    Das, Shoubhik; Li, Yuehui; Junge, Kathrin; Beller, Matthias

    2012-11-11

    Triiron dodecacarbonyl allows for the selective reduction of esters into the corresponding ethers. This protocol has a wide substrate scope. In addition, cholesteryl pelarogonate has been reduced under the reaction conditions with an excellent yield. PMID:23024977

  4. New phorbol and deoxyphorbol esters: isolation and relative potencies in inducing platelet aggregation and erythema of skin.

    PubMed

    Edwards, M C; Taylor, S E; Williamson, E M; Evans, F J

    1983-09-01

    Diester diterpenes based upon phorbol, 4-deoxyphorbol, 4 alpha-deoxyphorbol, 4-deoxy-5-hydroxyphorbol and 4,20-dideoxy-5-hydroxyphorbol were isolated from the fruit oil of Sapium indicum. Corresponding tri- and tetra-esters were produced by acetylation and mono-esters by selective hydrolysis. Twenty-six compounds were tested for production of erythema in vivo and induction of human and rabbit platelet aggregation in vitro. The flatter shape of the AB-ring trans compounds is necessary for interaction of phorbolesters at their receptor in that the cis analogues were inactive. The tertiary C-4 hydroxy group of phorbol was not necessary for activity although the 4-deoxy derivatives were less potent than the 4-hydroxy diterpenes. A primary hydroxy group at C-20 was essential for biological activity because the methyl and aldehyde derivatives of this position were inactive. The C-20 acetates were also inactive on platelets, but they did produce erythema, possibly because of the removal of the ester due to lipase activity in the skin. 5-hydroxy-analogues which undergo intramolecular hydrogen bonding had greatly reduced activities in both systems. Membrane stabilisers, phospholipase A2 and calmodulin inhibitors were antagonists for phorbol esters in platelet aggregation tests, whilst cyclo-oxygenase inhibitors and free radical scavengers had no inhibitory effects. Consequently, one electron withdrawal and free radical formation plays no part in the biological activity of these compounds. PMID:6637507

  5. Methods of refining and producing isomerized fatty acid esters and fatty acids from natural oil feedstocks

    DOEpatents

    Snead, Thomas E.; Cohen, Steven A.; Gildon, Demond L.; Beltran, Leslie V.; Kunz, Linda A.; Pals, Tessa M.; Quinn, Jordan R; Behrends, Jr., Raymond T.; Bernhardt, Randal J.

    2016-07-05

    Methods are provided for refining natural oil feedstocks and producing isomerized esters and acids. The methods comprise providing a C4-C18 unsaturated fatty ester or acid, and isomerizing the fatty acid ester or acid in the presence of heat or an isomerization catalyst to form an isomerized fatty ester or acid. In some embodiments, the methods comprise forming a dibasic ester or dibasic acid prior to the isomerizing step. In certain embodiments, the methods further comprise hydrolyzing the dibasic ester to form a dibasic acid. In certain embodiments, the olefin is formed by reacting the feedstock in the presence of a metathesis catalyst under conditions sufficient to form a metathesized product comprising olefins and esters, separating the olefins from the esters in the metathesized product, and transesterifying the esters in the presence of an alcohol to form a transesterified product having unsaturated esters.

  6. Formation of Aqueous Suspensions of Fullerenes

    EPA Science Inventory

    Colloidal suspensions of C60, C70 and a derivative of C60, PCBM ([6,6]-Phenyl C61-butyric acid methyl ester) were produced by extended mixing in water. We examined the contribution of background solution chemistry (pH, ionic strength) on the formation kinetics of colloidal suspe...

  7. Transport of Glutathione Diethyl Ester Into Human Cells

    NASA Astrophysics Data System (ADS)

    Levy, Ellen J.; Anderson, Mary E.; Meister, Alton

    1993-10-01

    Glutathione monoesters in which the carboxyl group of the glycine residue is esterified were previously found, in contrast to glutathione itself, to be effectively transported into various types of cells and to be converted intracellularly into glutathione. Glutathione monoesters are thus useful for prevention of oxidative stress, certain toxicities, and for treatment of glutathione deficiency. Glutathione diethyl ester is rapidly split to the glutathione monoethyl ester by mouse plasma glutathione diester α-esterase activity. Thus, as expected, glutathione mono- and diesters have similar effects on cellular glutathione levels in mice. However, human plasma lacks glutathione diester α-esterase thus, it became of interest to compare the transport properties of glutathione mono- and diesters in human cells. We found that human cells (erythrocytes, peripheral blood mononuclear cells, fibroblasts, ovarian tumor cells, and purified T cells) transport glutathione diethyl ester much more effectively than the corresponding monoethyl (glycyl) ester. Human cells rapidly convert glutathione diethyl ester to the monoester, whose intracellular levels rise to levels that are significantly higher than levels found after application of the monoester to the cells. High levels of the monoester provide the cells with a means of producing glutathione over a period of time. We conclude that glutathione diethyl ester is highly effective as a delivery agent for glutathione monoester, and thus for glutathione, in human cells and therefore could serve to decrease oxidative stress and toxicity. Hamster (and certain other animals) also lack plasma glutathione diester α-esterase and therefore would be suitable animal models. Previously reported toxicity of certain glutathione ester preparations appears to reflect the presence of impurities rather than effects of the esters.

  8. Metabolism of dibasic esters by rat nasal mucosal carboxylesterase.

    PubMed

    Bogdanffy, M S; Kee, C R; Hinchman, C A; Trela, B A

    1991-01-01

    Inhalation exposure of rats to dibasic esters revealed lesions of the nasal olfactory epithelium similar to those observed with other ester solvents. Female rats are more sensitive to these effects than are male rats. It has been proposed that carboxylesterase conversion of inhaled esters within nasal tissues to organic acids may be a critical biochemical step in converting these chemicals to toxic substances. These experiments measured the kinetic parameters Vmax, KM, Ksi, and V/K for the hydrolysis of the dibasic esters in the target nasal tissue, olfactory mucosa, and nontarget tissue, respiratory mucosa. It was determined that under the conditions of these experiments, diacid metabolites are not formed. Esterase activity was inhibited by pretreatment with bis p-nitrophenyl phosphate. Vmax values for the three dibasic esters were 5- to 13-fold greater in olfactory mucosa than respiratory mucosa for male or female rats. V/K values were 4- to 11-fold greater in olfactory mucosa than respiratory mucosa for male or female rats. V/K was similar between male and female olfactory mucosa when dimethyl glutarate was used as the substrate. With dimethyl succinate or dimethyl adipate as the substrate, V/K for female olfactory tissue was 0.5- or 2-fold that of males, respectively. Differences in V/K were mainly due to decreases in KM associated with increasing carbon chain length. Substrate inhibition was observed at dibasic ester concentrations greater than approximately 25 mM, which are unlikely to be achieved in vivo. These results lend further support to the hypothesis that organic acid accumulation in the target tissue, olfactory mucosa, plays a significant role in the pathogenesis of dibasic ester-induced nasal lesions. This mechanism may be applicable to a wide range of inhaled esters. PMID:1673384

  9. Solubility of HFCs in pentaerythritol tetraalkyl esters

    SciTech Connect

    Wahlstroem, A.; Vamling, L.

    2000-02-01

    The solubilities of difluoromethane (HFC32), 1,1,1,2,2-pentafluoroethane (HFC125), 1,1,1,2-tetrafluoroethane (HFC134a), 1,1,1-trifluoroethane (HFC143a) and 1,1-difluoroethane (HFC152a) in pentaerythritol tetranonanoate, pentaerythritol tetra-2-ethylbutanoate, and pentaerythritol tetra-2-ethylhexanoate have been measured at temperatures between 303 and 363 K and pressures between 0.07 and 2.1 MPa. Henry's constant and the activity coefficient for HFCs at infinite dilution were derived for measurements below 0.34 MPa. The measurements were made by an isochoric method with an uncertainty of <2% for Henry's constant and <3% at high pressure. Within the investigated temperature range, solubilities for HFCs in pentaerythritol tetraalkyl esters decrease in the following order: HFC152a > HFC134a > HFC32 > HFC125 > HFC143a. The experimental data have been correlated with a Flory-Huggins model with an extended temperature dependence, which is able to describe the data with a deviation from measured data of <2.7%.

  10. Kinetic modelling of vinyl ester resin polymerization

    SciTech Connect

    Dhulipala, R.; Kreig. G.; Hawley, M.C.

    1993-12-31

    The study of kinetics offers a substantional incentive in the endeavor to manufacture polymer matrix composites at high speeds. The study enables one to optimize the curing cycle based on the specific curing characteristics of the resin and also makes it possible to simulate the curing process. This paper reports the results of the modelling of the thermal curing of the vinyl ester resin. The parameters for the proposed model have been calculated based on conversion-vs-data generated at various temperatures and Benzoyl peroxide (initiator) concentrations. The extent of cure of the resin mixture was determined using Fourier Transform Infrared Spectroscopy. In this model the termination rate constant is considered to drop with extent of cure until a limiting value is reached. The limiting value is a consequence of the active chain ends possessing a degree of mobility due to the propagation reaction even though the translational motion of the growing for radicals in increasingly restricted with conversion. Good agreements is observed between the model predictions and the experimental data.

  11. Levels of Phosphate Esters in Spirodela

    PubMed Central

    Bieleski, R. L.

    1968-01-01

    The duckweed Spirodela oligorrhiza was grown in sterile nutrient solutions that contained 1 mm phosphate-32P at various specific activities. In solutions with activities higher than 2 μc per μmole per ml, plant growth was inhibited after a time, and the physical appearance of the plants was affected. The critical level of radiation, at which growth was first affected, corresponded to 5 kilorads. Plants were grown for 9 days (5 generations) in a culture solution containing phosphate at 0.5 μc per μmole per ml (radiation load approx 0.5 kilorads) so that all phosphorus-containing materials in the tissue became uniformly labeled. The various radioactive compounds were extracted, chromatographed, identified, and their radioactivity was measured. From this radioactivity plus the specific activity of the supplied phosphate, the amount of each compound was calculated. The data constitute a complete balance-sheet for phosphorus in a plant tissue. The identity of 98% of the phosphorus in the tissue was determined. Inorganic phosphate (32,700 mμmoles/g fr wt) was the predominant phosphorus-containing compound; RNA (5100 mμmoles P/g fr wt) was the main organic phosphate; phosphatidyl choline (1600 mμmoles/g fr wt) was the main phospholipid, and glucose-6-phosphate (500 mμmoles/g fr wt) the main acid-soluble phosphate ester. Amounts of other phosphorus compounds are given. Images PMID:16656910

  12. Generation, Isolation, and Characterization of a Stable Enol from Grignard Addition to a Bis-Ester: A Microscale Experiment for the Undergraduate Organic Chemistry Laboratory

    ERIC Educational Resources Information Center

    Nicaise, Olivier J. C.; Ostrom, Kyle F.; Dalke, Brent J.

    2005-01-01

    An experiment is described that introduces students to the concept of temperature-dependent stability of the tetrahedral intermediate in an acyl-transfer reaction. The process involves the determination of the structure of an alpha-ketoester and its corresponding remarkably stable enol ester to suggest a mechanism for the formation of the products.

  13. Differences in Substrate Specificities of Five Bacterial Wax Ester Synthases

    PubMed Central

    Wahlen, Bradley D.; Garner, EmmaLee; Wei, Jiashi; Seefeldt, Lance C.

    2012-01-01

    Wax esters are produced in certain bacteria as a potential carbon and energy storage compound. The final enzyme in the biosynthetic pathway responsible for wax ester production is the bifunctional wax ester synthase/acyl-coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT), which utilizes a range of fatty alcohols and fatty acyl-CoAs to synthesize the corresponding wax ester. We report here the isolation and substrate range characterization for five WS/DGAT enzymes from four different bacteria: Marinobacter aquaeolei VT8, Acinetobacter baylyi, Rhodococcus jostii RHA1, and Psychrobacter cryohalolentis K5. The results from kinetic studies of isolated enzymes reveal a differential activity based on the order of substrate addition and reveal subtle differences between the substrate selectivity of the different enzymes. These in vitro results are compared to the wax ester and triacylglyceride product profiles obtained from each organism grown under neutral lipid accumulating conditions, providing potential insights into the role that the WS/DGAT enzyme plays in determining the final wax ester products that are produced under conditions of nutrient stress in each of these bacteria. Further, the analysis revealed that one enzyme in particular from M. aquaeolei VT8 showed the greatest potential for future study based on rapid purification and significantly higher activity than was found for the other isolated WS/DGAT enzymes. The results provide a framework to test prospective differences between these enzymes for potential biotechnological applications such as high-value petrochemicals and biofuel production. PMID:22685145

  14. Strategies for the analysis of highly reactive pinacolboronate esters.

    PubMed

    Zhong, Qiqing; Ngim, Kenley K; Sun, Megan; Li, Jane; Deese, Alan; Chetwyn, Nik P

    2012-03-16

    Pinacolboronate esters (or boronic acid, pinacol esters) are widely used in the Suzuki coupling reaction to connect organic building blocks for the total synthesis of complex molecules. The 2-aminopyrimidine-5-pinacolboronate ester was used as a starting material in the synthesis of a development compound, necessitating a chromatographic purity method to assess its quality. This aryl pinacolboronate ester posed unique analytical challenges due to its facile hydrolysis to the corresponding boronic acid, which is nonvolatile and poorly soluble in organic solvents. This made GC and normal-phase HPLC analysis unsuitable. In reversed-phase mode, typical sample preparation and analysis conditions promoted rapid sample degradation to the boronic acid. To overcome these challenges, unconventional approaches were necessary in order to stabilize 2-aminopyrimidine-5-pinacolboronate ester, adequately solubilize its boronic acid, and produce acceptable separation and retention. The final method employed non-aqueous and aprotic diluent, and a reversed-phase separation using highly basic mobile phases (pH 12.4) with an ion pairing reagent. These strategies were successfully applied to several other reactive pinacolboronate esters for purity analysis, demonstrating broad applicability to this unique class of compounds. PMID:22321949

  15. Nanohydroxyapatite/poly(ester urethane) scaffold for bone tissue engineering.

    PubMed

    Boissard, C I R; Bourban, P-E; Tami, A E; Alini, M; Eglin, D

    2009-11-01

    Biodegradable viscoelastic poly(ester urethane)-based scaffolds show great promise for tissue engineering. In this study, the preparation of hydroxyapatite nanoparticles (nHA)/poly(ester urethane) composite scaffolds using a salt-leaching-phase inverse process is reported. The dispersion of nHA microaggregates in the polymer matrix were imaged by microcomputed X-ray tomography, allowing a study of the effect of the nHA mass fraction and process parameters on the inorganic phase dispersion, and ultimately the optimization of the preparation method. How the composite scaffold's geometry and mechanical properties change with the nHA mass fraction and the process parameters were assessed. Increasing the amount of nHA particles in the composite scaffold decreased the porosity, increased the wall thickness and consequently decreased the pore size. The Young's modulus of the poly(ester urethane) scaffold was improved by 50% by addition of 10 wt.% nHA (from 0.95+/-0.5 to 1.26+/-0.4 MPa), while conserving poly(ester urethane) viscoelastic properties and without significant changes in the scaffold macrostructure. Moreover, the process permitted the inclusion of nHA particles not only in the poly(ester urethane) matrix, but also at the surface of the scaffold pores, as shown by scanning electron microscopy. nHA/poly(ester urethane) composite scaffolds have great potential as osteoconductive constructs for bone tissue engineering. PMID:19442765

  16. An approach based on ultrahigh performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry allowing the quantification of both individual phytosteryl and phytostanyl fatty acid esters in complex mixtures.

    PubMed

    Scholz, Birgit; Menzel, Nicole; Lander, Vera; Engel, Karl-Heinz

    2016-01-15

    A method for the analysis of both individual phytosteryl and phytostanyl fatty acid esters in complex mixtures was established. The approach was based on a previously not described combination of three elements: (i) the formation of [M-FA+H](+) fragment ions via APCI (atmospheric pressure chemical ionization), (ii) a highly efficient UHPLC-based separation on a 1.7 μ C8 column, previously established for phytostanyl fatty acid esters, allowing the distinction of individual fatty acid esters sharing the same sterol/stanol nucleus and of isotope peaks of phytosteryl fatty acid esters and corresponding phytostanyl fatty acid esters based on these [M-FA+H](+) fragment ions, and (iii) the adjustment of the APCI conditions allowing the differential APCI-MS-SIM (single ion monitoring) detection of phytostanyl esters of linoleic and linolenic acid based on their distinct formation of a [M+H](+) ion. The usefulness of the methodology was demonstrated by the analysis of a commercially available enriched margarine. Two runs per sample allowed the quantification of 35 target analytes; the total amounts of esters were between 124.7 and 125.3g/kg, being in good agreement with the labelled 125 g/kg. Validation data were elaborated for 35 individual fatty acid esters of sitosterol, campesterol, brassicasterol, stigmasterol, sitostanol and campestanol. Recovery rates ranged from 95 to 106%; the coefficients of variation were consistently <5%, except for stigmasteryl-18:1. The approach describes for the first time a quantification of both individual phytosteryl and phytostanyl fatty acid esters and thus closes an analytical gap related to this class of health-relevant food constituents. PMID:26718186

  17. ESTIMATION OF HYDROLYSIS RATE CONSTANTS OF CARBOXYLIC ACID ESTER AND PHOSPHATE ESTER COMPOUNDS IN AQUEOUS SYSTEMS FROM MOLECULAR STRUCTURE BY SPARC

    EPA Science Inventory

    SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid ester and phosphate ester compounds in aqueous non- aqueous and systems strictly from molecular structure. The energy diffe...

  18. Efficient production of the Nylon 12 monomer ω-aminododecanoic acid methyl ester from renewable dodecanoic acid methyl ester with engineered Escherichia coli.

    PubMed

    Ladkau, Nadine; Assmann, Miriam; Schrewe, Manfred; Julsing, Mattijs K; Schmid, Andreas; Bühler, Bruno

    2016-07-01

    The expansion of microbial substrate and product scopes will be an important brick promoting future bioeconomy. In this study, an orthogonal pathway running in parallel to native metabolism and converting renewable dodecanoic acid methyl ester (DAME) via terminal alcohol and aldehyde to 12-aminododecanoic acid methyl ester (ADAME), a building block for the high-performance polymer Nylon 12, was engineered in Escherichia coli and optimized regarding substrate uptake, substrate requirements, host strain choice, flux, and product yield. Efficient DAME uptake was achieved by means of the hydrophobic outer membrane porin AlkL increasing maximum oxygenation and transamination activities 8.3 and 7.6-fold, respectively. An optimized coupling to the pyruvate node via a heterologous alanine dehydrogenase enabled efficient intracellular L-alanine supply, a prerequisite for self-sufficient whole-cell transaminase catalysis. Finally, the introduction of a respiratory chain-linked alcohol dehydrogenase enabled an increase in pathway flux, the minimization of undesired overoxidation to the respective carboxylic acid, and thus the efficient formation of ADAME as main product. The completely synthetic orthogonal pathway presented in this study sets the stage for Nylon 12 production from renewables. Its effective operation achieved via fine tuning the connectivity to native cell functionalities emphasizes the potential of this concept to expand microbial substrate and product scopes. PMID:26969251

  19. Theoretical studies of fundamental pathways for alkaline hydrolysis of carboxylic acid esters in gas phase

    SciTech Connect

    Zhan, C.G.; Landry, D.W.; Ornstein, R.L.

    2000-02-23

    Fundamental reaction pathways for the alkaline hydrolysis of carboxylic acid esters, RCOOR{prime}, were examined through a series of first-principle calculations. The reactions of six representative esters with hydroxide ion were studied in the gas phase. A total of three competing reaction pathways were found and theoretically confirmed for each of the esters examined: bimolecular base-catalyzed acyl-oxygen cleavage (B{sub AC}2), bimolecular base-catalyzed alkyl-oxygen cleavage (B{sub AL}2), and carbonyl oxygen exchange with hydroxide. For the two-step B{sub AC}2 process, this is the first theoretical study to consider the individual sub-steps of the reaction process and to consider substituent effects. For the carbonyl oxygen exchange with hydroxide and for the one-step B{sub AL}2 process, the authors report here the first quantitative theoretical results for the reaction pathways and for the energy barriers. The energy barrier calculated for the second step of the B{sub AC}2 process, that is, the decomposition of the tetrahedral intermediate, is larger in the gas phase than that of the first step, that is, the formation of the tetrahedral intermediate, for all but one of the esters examined. The exception, CH{sub 3}COOC(CH{sub 3}){sub 3}, does not have an {alpha} hydrogen in the leaving group. The highest energy barrier calculated for the B{sub AC}2 process is always lower than the barriers for the oxygen exchange and for the B{sub AL}2 process. The difference between the barrier for the B{sub AL}2 process and the highest barrier for the B{sub AC}2 process is only {approximately}1--3 kcal/mol for the methyl esters, but becomes much larger for the others. Substitution of an {alpha} hydrogen in R{prime} with a methyl group considerably increases the energy barrier for the B{sub AL}2 process, and significantly decreases the energy barrier for the second step of the B{sub AC}2 process. The calculated substituent shifts of the energy barrier for the first step of the

  20. The transition from linear to highly branched poly(β-amino ester)s: Branching matters for gene delivery.

    PubMed

    Zhou, Dezhong; Cutlar, Lara; Gao, Yongsheng; Wang, Wei; O'Keeffe-Ahern, Jonathan; McMahon, Sean; Duarte, Blanca; Larcher, Fernando; Rodriguez, Brian J; Greiser, Udo; Wang, Wenxin

    2016-06-01

    Nonviral gene therapy holds great promise but has not delivered treatments for clinical application to date. Lack of safe and efficient gene delivery vectors is the major hurdle. Among nonviral gene delivery vectors, poly(β-amino ester)s are one of the most versatile candidates because of their wide monomer availability, high polymer flexibility, and superior gene transfection performance both in vitro and in vivo. However, to date, all research has been focused on vectors with a linear structure. A well-accepted view is that dendritic or branched polymers have greater potential as gene delivery vectors because of their three-dimensional structure and multiple terminal groups. Nevertheless, to date, the synthesis of dendritic or branched polymers has been proven to be a well-known challenge. We report the design and synthesis of highly branched poly(β-amino ester)s (HPAEs) via a one-pot "A2 + B3 + C2"-type Michael addition approach and evaluate their potential as gene delivery vectors. We find that the branched structure can significantly enhance the transfection efficiency of poly(β-amino ester)s: Up to an 8521-fold enhancement in transfection efficiency was observed across 12 cell types ranging from cell lines, primary cells, to stem cells, over their corresponding linear poly(β-amino ester)s (LPAEs) and the commercial transfection reagents polyethyleneimine, SuperFect, and Lipofectamine 2000. Moreover, we further demonstrate that HPAEs can correct genetic defects in vivo using a recessive dystrophic epidermolysis bullosa graft mouse model. Our findings prove that the A2 + B3 + C2 approach is highly generalizable and flexible for the design and synthesis of HPAEs, which cannot be achieved by the conventional polymerization approach; HPAEs are more efficient vectors in gene transfection than the corresponding LPAEs. This provides valuable insight into the development and applications of nonviral gene delivery and demonstrates great prospect for their

  1. Rape oil methyl ester (RME) and used cooking oil methyl ester (UOME) as alternative fuels

    SciTech Connect

    Hohl, G.H.

    1995-12-31

    The author presents a review about the fleet tests carried out by the Austrian Armed Forces concerning the practical application of a vegetable oil, i.e Rape Oil Methyl Ester (RME) and Used Cooking Oil Methyl Ester (UOME) as alternative fuels for vehicles under military conditions, and reviews other research results carried out in Austria. As a result of over-production in Western European agriculture, the increase in crop yields has led to tremendous surpluses. Alternative agricultural products have been sought. One alternative can be seen in biological fuel production for tractors, whereby the farmer is able to produce his own fuel supply as was the case when he previously provided self-made feed for his horses. For the market introduction different activities were necessary. A considerable number of institutes and organizations including the Austrian Armed Forces have investigated, tested and developed these alternative fuels. The increasing disposal problems of used cooking oil have initiated considerations for its use. The recycling of this otherwise waste product, and its preparation for use as an alternative fuel to diesel oil, seems to be most promising.

  2. Fragrance material review on anisyl formate.

    PubMed

    McGinty, D; Letizia, C S; Api, A M

    2012-09-01

    A toxicologic and dermatologic review of anisyl formate when used as a fragrance ingredient is presented. Anisyl formate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate, and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for anisyl formate were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414650

  3. Oxidative degradation of cholesteryl esters in low-density lipoproteins: analysis by liquid chromatography-light scattering and protection by a new synthetic antioxidant, S20478.

    PubMed

    Arborati, M; Benchorba, D; Lesieur, I; Bizot-Espiard, J G; Guardiola-Lemaitre, B; Chapman, M J; Ninio, E

    1997-01-01

    Cholesteryl esters in the hydrophobic core of low-density lipoprotein (LDL) particles constitute a major molecular target during copper-mediated oxidation. To facilitate the rapid analysis and quantitation of the oxidative degradation of LDL cholesteryl esters, we describe a new approach based on light scattering detection following separation by HPLC. We have applied this approach to the evaluation of the protective capacity of a new synthetic antioxidant, S20478, during oxidation of LDL in the presence of copper ions. HPLC separation of cholesterol and the four major molecular species of cholesteryl esters (C16:0, C18:1, C18:2 and C20:4) of LDL was achieved in a single run of 20 min with high sensitivity (50 ng) and low background. Time course studies of the oxidative modification of LDL (ratio LDL protein: copper, 100 micrograms/mL: 1 microM) revealed that the content of unsaturated cholesteryl esters (C20:4 and C18:2) decreased (-30% and -15%, respectively) within 90 min of copper-mediated oxidation, while only minor degradation (up to 15%) of monounsaturated (C18:1) and saturated (C16:0) esters occurred. At 24 hours of oxidation, only traces (< 5%) of the C20:4 and C18:2 esters were detectable; whereas 52% of the C18:1 ester remained (P < 0.01). Of the saturated esters, only minor proportions (35% or less) underwent oxidative modification. In addition, some 81% of free cholesterol was conserved as the native sterol. The synthetic antioxidant, S20478 (50 microM) was capable of inhibiting the initiation and the propagation of copper-mediated LDL oxidation as determined by the time- and dose-dependent inhibition of the formation of conjugated dienes and thiobarbituric acid-reactive substances, as well as the conservation of the net electrical charge of LDL; indeed S20478 conserved cholesteryl esters in their native form up to 24 hours. However, after prolonged exposure to copper ions (48 hours), only 47% of the unsaturated esters remained (C18:2, P < 0

  4. Increase of fruity aroma during mixed T. delbrueckii/S. cerevisiae wine fermentation is linked to specific esters enhancement.

    PubMed

    Renault, Philippe; Coulon, Joana; de Revel, Gilles; Barbe, Jean-Christophe; Bely, Marina

    2015-08-17

    The aim of this work was to study ester formation and the aromatic impact of Torulaspora delbrueckii when used in association with Saccharomyces cerevisiae during the alcoholic fermentation of must. In order to evaluate the influence of the inoculation procedure, sequential and simultaneous mixed cultures were carried out and compared to pure cultures of T. delbrueckii and S. cerevisiae. Our results showed that mixed inoculations allowed the increase, in comparison to S. cerevisiae pure culture, of some esters specifically produced by T. delbrueckii and significantly correlated to the maximal T. delbrueckii population reached in mixed cultures. Thus, ethyl propanoate, ethyl isobutanoate and ethyl dihydrocinnamate were considered as activity markers of T. delbrueckii. On the other hand, isobutyl acetate and isoamyl acetate concentrations were systematically increased during mixed inoculations although not correlated with the development of either species but were rather due to positive interactions between these species. Favoring T. delbrueckii development when performing sequential inoculation enhanced the concentration of esters linked to T. delbrueckii activity. On the contrary, simultaneous inoculation restricted the growth of T. delbrueckii, limiting the production of its activity markers, but involved a very important production of numerous esters due to more important positive interactions between species. These results suggest that the ester concentrations enhancement via interactions during mixed modalities was due to S. cerevisiae production in response to the presence of T. delbrueckii. Finally, sensory analyses showed that mixed inoculations between T. delbrueckii and S. cerevisiae allowed to enhance the complexity and fruity notes of wine in comparison to S. cerevisiae pure culture. Furthermore, the higher levels of ethyl propanoate, ethyl isobutanoate, ethyl dihydrocinnamate and isobutyl acetate in mixed wines were found responsible for the increase of

  5. Lipoprotein products of lecithin: cholesterol acyltransferase and cholesteryl ester transfer.

    PubMed

    Rose, H G; Ellerbe, P

    1982-09-14

    High-density lipoprotein substrates and products of human plasma lecithin: cholesterol acyltransferase have been labelled with radioisotopic cholesteryl esters in order to facilitate identification. [3H]Cholesteryl esters were formed by endogenous HDL3/VHDL enzyme (d greater than 1.125 g/ml) following incubation with mixed vesicles of phosphatidylcholine, unesterified cholesterol and 3H-labelled unesterified cholesterol. Transfer of labelled esters to acceptor lipoproteins (VLDL+LDL, d less than 1.063 g/ml) was employed to distinguish a hypothetical transfer complex. Separation of labelled HDL3/VHDL was by gel-permeation chromatography. The results indicate that a subpopulation of labelled HDL3/VHDL cholesteryl esters (43-61% of total) were removed by VLDL/LDL during a 3 h transfer period and these derive from the smaller lipoproteins of the spectrum. HDL carrying non-transferable [3H]cholesteryl esters localize to the larger HDL3. Transfer rates were proportional to ratios of acceptor to donor lipoproteins. Net transfer of cholesteryl esters from the smaller HDL3 also occurred, but was smaller in magnitude (about 10.5% of total). Acyltransferase assays indicated that enzyme distribution is skewed to larger-sized HDL3, suggesting that the non-transferable components might be lecithin: cholesterol acyltransferase-containing parent complexes, while the smaller transfer products contain little acyltransferase. The results fit the hypothesis that a parent HDL3-lecithin: cholesterol acyltransferase complex generates a smaller-sized lipoprotein product which is active in cholesteryl ester transport. PMID:7126623

  6. Chemiluminescence from alkoxy-substituted acridinium dimethylphenyl ester labels.

    PubMed

    Natrajan, Anand; Sharpe, David; Wen, David

    2012-05-01

    Chemiluminescent acridinium dimethylphenyl ester labels are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered by alkaline peroxide in the presence of the cationic surfactant cetyltrimethylammonium chloride (CTAC). The surfactant plays a critical role in the chemiluminescence process of these labels by both accelerating their emission kinetics and increasing total light output enabling high throughout and improved assay sensitivity in automated immunoassays. Despite the surfactant's crucial role in the chemiluminescent reaction, no study has investigated how structural perturbations in the acridinium ring could impact the influence of the surfactant. We describe herein the synthesis and properties of three new alkoxy-substituted, acridinium dimethylphenyl esters where the nature of the alkoxy group in the acridinium ring was varied (hydrophobic or hydrophilic). Chemiluminescence measurements of these alkoxy-substituted labels indicate that hydrophilic functional groups in the acridinium ring, in particular sulfobetaine zwitterions, disrupt surfactant-mediated compression of emission times but not enhancement of light yield. These results support the hypothesis that surfactant-mediated effects require the binding of two different reaction intermediates to surfactant aggregates and, that surfactants influence light emission from acridinium esters by two separate mechanisms. Our studies also indicate that preservation of both surfactant effects on acridinium ester chemiluminescence and low non-specific binding of the label can be achieved with a relatively hydrophobic acridinium ring coupled to a hydrophilic phenolic ester leaving group. PMID:22441905

  7. Reaction of 2,5-bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone with phosphonoacetic acid trimethyl ester

    SciTech Connect

    Fuzhenkova, A.V.; Galyautdinov, N.I.; Vagapova, N.N.

    1987-12-20

    It is known that the ease of the 1,5 migration of groups in cyclopentadienes is associated with their acceptor power. On the basis of this and in view of the tendency of phosphonoacetic acid triester to react at the C=O group of ..cap alpha..-enols (Wittig-Horner reaction), the authors studied the reactions of phosphonoacetic acid trimethyl ester with cyclones. 2,5-Bis(methoxycarbonyl)-3,4-diphenylcyclopentadienone reacts with the sodium derivative of phosphonoacetic acid trimethyl ester with the formation of adducts in which the carbanion center of the reagent is linked to the C/sup 2/ atom of cyclopentadienone. The IR spectra were determined on a UR-10 spectrometer. The PMR spectra were recorded on Varian T-60 and Tesla BS-467A spectrometer, solvent CHCl/sub 3/ or CDCl/sub 3/, internal standard TMS.

  8. Specificity and formation of unusual amino acids of an amide ligation strategy for unprotected peptides.

    PubMed

    Tam, J P; Rao, C; Liu, C F; Shao, J

    1995-03-01

    An important step in the recently developed ligation strategy known as domain ligation strategy to link unprotected peptide segments without activation is the ring formation between the C-terminal ester aldehyde and the N-terminal amino acid bearing a beta-thiol or beta-hydroxide. A new method was developed to define the specificity of this reaction using a dye-labeled alanyl ester aldehyde to react with libraries of 400 dipeptides which contained all dipeptide combinations of the 20 genetically coded amino acids. Three different ester aldehydes of the dye-labeled alanine: alpha-formylmethyl (FM), beta-formylethyl (FE), and beta,beta,beta-dimethyl and formylethyl esters (DFE), were examined. The DFE ester was overly hindered and reacted with N-terminal Cys dipeptides (Cys-X). Interestingly, it also reacted slowly with the sequences of X-Gly where Gly was the second amino acid and the X-Gly amide bond participated in the ring formation. Although the FE ester reacted similarly as the FM ester in the ring formation, the subsequent O,N-acyl transfer was at least 30-fold slower than those of the FM-ester. The FM alpha-formyl methyl ester was the most suitable ester and was reactive with dipeptides of six N-terminal amino acids: Cys, Thr, Trp, Ser, His and Asn. The order and extent of their reactivity were highly dependent on pH, solvent and neighboring participation by the adjacent amino acid. In general, they could be divided into three categories. (1) N-Terminal Cys and Thr were the most reactive.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7775013

  9. Gas Phase Spectroscopic Investigation of Chromate-Esters

    NASA Astrophysics Data System (ADS)

    Kaufman, Sydney H.; Weber, J. Mathias

    2012-06-01

    Chromate and dichromate ions are frequently used in the oxidation of alcohols. Chromate esters containing a Cr--O--C bridge are thought to be important intermediates in such reactions. We report the photofragment action spectra of two chromate ester complexes in the UV and visible regions, both of which primarily undergo cleavage of the chromate ester bond resulting in reduction of the chromate from Cr(VI) to Cr(V). Comparison to the UV/Vis absorption spectrum of a methanolic dichromate solution suggests the electronic transitions are the same ligand-to-metal charge transfer transitions in both environments. Comparing the spectral features for different fragment channels leads to insight into the energetics and fragmentation mechanism of these species.

  10. Ester oxidation on an aluminum surface using chemiluminescence

    NASA Technical Reports Server (NTRS)

    Jones, William R., Jr.; Meador, Michael A.; Morales, Wilfredo

    1986-01-01

    The oxidation characteristics of a pure ester (trimethyolpropane triheptanoate) were studied by using a chemiluminescence technique. Tests were run in a thin film microoxidation apparatus with an aluminum alloy catalyst. Conditions included a pure oxygen atmosphere and a temperature range of 176 to 206 C. Results indicated that oxidation of the ester (containing .001 M diphenylanthracene as an intensifier) was accompanied by emission of light. The maximum intensity of light emission was a function of the amount of ester, the concentration of intensifier, and the test temperature. The induction period, or the time to reach one-half of maximum intensity was inversely proportional to test temperature. Decreases in light emission at the later stages of a test were caused by depletion of the intensifier.

  11. Maximization of fructose esters synthesis by response surface methodology.

    PubMed

    Neta, Nair Sampaio; Peres, António M; Teixeira, José A; Rodrigues, Ligia R

    2011-07-01

    Enzymatic synthesis of fructose fatty acid ester was performed in organic solvent media, using a purified lipase from Candida antartica B immobilized in acrylic resin. Response surface methodology with a central composite rotatable design based on five levels was implemented to optimize three experimental operating conditions (temperature, agitation and reaction time). A statistical significant cubic model was established. Temperature and reaction time were found to be the most significant parameters. The optimum operational conditions for maximizing the synthesis of fructose esters were 57.1°C, 100 rpm and 37.8 h. The model was validated in the identified optimal conditions to check its adequacy and accuracy, and an experimental esterification percentage of 88.4% (±0.3%) was obtained. These results showed that an improvement of the enzymatic synthesis of fructose esters was obtained under the optimized conditions. PMID:21356336

  12. Boric Ester-Type Molten Salt via Dehydrocoupling Reaction

    PubMed Central

    Matsumi, Noriyoshi; Toyota, Yoshiyuki; Joshi, Prerna; Puneet, Puhup; Vedarajan, Raman; Takekawa, Toshihiro

    2014-01-01

    Novel boric ester-type molten salt was prepared using 1-(2-hydroxyethyl)-3-methylimidazolium chloride as a key starting material. After an ion exchange reaction of 1-(2-hydroxyethyl)-3-methylimidazolium chloride with lithium (bis-(trifluoromethanesulfonyl) imide) (LiNTf2), the resulting 1-(2-hydroxyethyl)-3-methylimidazolium NTf2 was reacted with 9-borabicyclo[3.3.1]nonane (9-BBN) to give the desired boric ester-type molten salt in a moderate yield. The structure of the boric ester-type molten salt was supported by 1H-, 13C-, 11B- and 19F-NMR spectra. In the presence of two different kinds of lithium salts, the matrices showed an ionic conductivity in the range of 1.1 × 10−4–1.6 × 10−5 S cm−1 at 51 °C. This was higher than other organoboron molten salts ever reported. PMID:25405738

  13. Isolation and pharmacological activity of phenylpropanoid esters from Marrubium vulgare.

    PubMed

    Sahpaz, Sevser; Garbacki, Nancy; Tits, Monique; Bailleul, Francois

    2002-03-01

    The isolation and identification of major phenylpropanoid esters from Marrubium vulgare: (+) (E)-caffeoyl-L-malic acid 1, acteoside 2, forsythoside B 3, arenarioside 4, ballotetroside 5, as well as their anti-inflammatory activity are reported for the first time. We evaluated the inhibitory effects of these five compounds on cyclooxygenase (Cox) catalysed prostaglandin biosynthesis activity. Only the glycosidic phenylpropanoid esters showed an inhibitory activity towards the Cox-2 enzyme and three of them: acteoside 2, forsythoside B 3, arenarioside 4, exhibited higher inhibitory potencies on Cox-2 than on Cox-1. These results are of interest, as Cox-2 is mainly associated with inflammation and the Cox-1 inhibition with adverse side effects often observed with non-steroidal anti-inflammatory drugs. The occurrence of these phenylpropanoid esters could also explain some other pharmacological properties of M. vulgare. PMID:11849848

  14. Removal of cholesteryl ester from hepatic reticuloendothelial cells in vivo is not enhanced by plasma cholesteryl ester transfer protein.

    PubMed

    Stein, O; Dabach, Y; Hollander, G; Stein, Y

    1991-01-28

    The putative role of cholesteryl ester transfer protein (CETP) in the removal of cholesteryl ester from hepatic reticuloendothelial cells in vivo was studied in hamsters. The parameter tested was retention of [3H]cholesteryl linoleyl ether ([3H]CLE), a nonhydrolysable analog of cholesteryl ester, in the liver after injection of [3H]CLE labeled acetylated LDL, which is targetted to nonparenchymatous littoral cells. In hamsters fed laboratory chow, plasma cholesteryl ester transfer activity (CETA) was 10.6 +/- 0.9 units and the retention of [3H]CLE in the liver 28 days after injection was 86% of the 4 h value. It was about 55% in rats fed the same diet, in which CETA was not detectable. When the diet was supplemented with 2% cholesterol and 15% margarine, CETA activity in hamsters increased 2-fold, yet no change in retention of [3H]CLE in liver was seen after 28 days. In rats, the retention of [3H]CLE in the liver was also not changed by the dietary fat supplementation. These results do not support the role of CETP in vivo in removal of cholesteryl ester from intact reticuloendothelial cells. PMID:1998742

  15. Preparation and physical properties of chitin fatty acids esters.

    PubMed

    Yang, Byung Y; Ding, Qiong; Montgomery, Rex

    2009-02-17

    Trifluoroacetic anhydride is an effective promoter for the preparation of chitin single- and mixed-acid esters. Complete dissolution is achieved within 30 min when powdered chitin is heated at 70 degrees C in a mixed solution of carboxylic acid(s) and trifluoroacetic anhydride. Chitin esters prepared are chitin acetate, chitin butyrate, chitin hexanoate and chitin octanoate, chitin co-acetate/butyrate, chitin co-acetate/hexanoate, chitin co-acetate/octanoate, chitin co-acetate/palmitate, each from a solution of the respective reactants. The products have degrees of O-acyl substitution in a range of DS 1-2 depending on the nature of acyl group, as analyzed by gas-liquid and high-pressure liquid chromatography. Acetic acid as a mutual component for the mixed-acid esters increases the total degree of substitution, and the acetyl substitution is close to the relative distribution in the reaction mixture for chitin co-acetate/butyrate. It is favored over hexanoate, octanoate, and palmitate. The parent molecules, as calculated by the composition of the chitin esters and their molecular weights by light-scattering spectroscopy, are 30 kDa for the smallest and 150-151 kDa for the largest. Films of these chitin derivatives when cast from solution are strong and flexible with limited extensibility. By dynamic mechanical analysis of the ester film, it was found that both the glass transition temperature (T(g)) and the tensile modulus (E' at 25 degrees C) are highest for chitin acetate (218 degrees C and 5.8 GPa), and lowest for chitin octanoate (182 degrees C and 1.5 GPa). For the other esters, these values lie between the above-cited values, where the T(g) and the E' decrease with an increase in the chain length of the acyl constituent. PMID:19091309

  16. Application of Ester based Drilling Fluid for Shale Gas Drilling

    NASA Astrophysics Data System (ADS)

    Sauki, Arina; Safwan Zazarli Shah, Mohamad; Bakar, Wan Zairani Wan

    2015-05-01

    Water based mud is the most commonly used mud in drilling operation. However, it is ineffective when dealing with water-sensitive shale that can lead to shale hydration, consequently wellbore instability is compromised. The alternative way to deal with this kind of shale is using synthetic-based mud (SBM) or oil-based mud (OBM). OBM is the best option in terms of technical requirement. Nevertheless, it is toxic and will create environmental problems when it is discharged to onshore or offshore environment. SBM is safer than the OBM. The aim of this research is to formulate a drilling mud system that can carry out its essential functions for shale gas drilling to avoid borehole instability. Ester based SBM has been chosen for the mud formulation. The ester used is methyl-ester C12-C14 derived from palm oil. The best formulation of ester-based drilling fluid was selected by manipulating the oil-water ratio content in the mud which are 70/30, 80/20 and 90/10 respectively. The feasibility of using this mud for shale gas drilling was investigated by measuring the rheological properties, shale reactivity and toxicity of the mud and the results were compared with a few types of OBM and WBM. The best rheological performance can be seen at 80/20 oil-water ratio of ester based mud. The findings revealed that the rheological performance of ester based mud is comparable with the excellent performance of sarapar based OBM and about 80% better than the WBM in terms of fluid loss. Apart from that, it is less toxic than other types of OBM which can maintain 60% prawn's survival even after 96 hours exposure in 100,000 ppm of mud concentration in artificial seawater.

  17. Raman spectroscopic analysis of isomers of biliverdin dimethyl ester.

    PubMed

    Matysik, J; Hildebrandt, P; Smit, K; Mark, F; Gärtner, W; Braslavsky, S E; Schaffner, K; Schrader, B

    1997-06-01

    The constitutional isomers of biliverdin dimethyl ester, IX alpha and XIII alpha, were studied by resonance Raman spectroscopy. The far-reaching spectral similarities suggest that despite the different substitution patterns, the compositions of the normal modes are closely related. This conclusion does not hold only for the parent state (ZZZ, sss configuration) but also for the configurational isomers which were obtained upon double-bond photoisomerization. Based on a comparison of the resonance Raman spectra, a EZZ configuration is proposed for one of the two photoisomers of biliverdin dimethyl ester IX alpha, while a ZZE, ssa configuration has been assigned previously to the second isomer. PMID:9226559

  18. Effect of ester impurities in PMR-polyimide resin

    NASA Technical Reports Server (NTRS)

    Lauver, R. W.

    1976-01-01

    Spectral and chomatographic studies were conducted which established the presence of tri- and tetraester impurities in aged monomer solutions employed in fabrication of PMR-polyimide resin composites. The equilibrium constant and apparent rate of the esterification were determined. It was demonstrated, using differential scanning calorimetry, that the ortho-ester moiety of these impurities does not completely react at typical cure conditions. It is concluded that voids formed in composites fabricated with aged monomer solution are due to gaseous decomposition products evolved by ester impurities and/or unreacted amine during elevated temperature post-cure treatment.

  19. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  20. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  1. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  2. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  3. 40 CFR 721.10125 - Alkenedioic acid, dialkyl ester, reaction products with polyaminocarbomonocycle and alkenoic acid...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... (1) The chemical substances identified generically as alkenedioic acid, dialkyl ester, reaction..., reaction products with polyaminocarbomonocycle and alkenoic acid alkyl ester (generic). 721.10125 Section... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific...

  4. Self-Motion Depending on the Physicochemical Properties of Esters as the Driving Force

    ERIC Educational Resources Information Center

    Nakata, Satoshi; Matsuo, Kyoko; Kirisaka, Junko

    2007-01-01

    The self-motion of an ester boat is investigated depending on the physicochemical properties of the surface-active substance. The results show that the ester boat moves towards the higher surface tension generating as the driving force.

  5. Ethyl ester production by homogeneous alkaline transesterification: influence of the catalyst.

    PubMed

    Mendow, G; Veizaga, N S; Querini, C A

    2011-06-01

    In this work, the process for ethyl ester production is studied using refined sunflower oil, and NaOH, KOH, CH(3)ONa, and CH(3)OK, as catalysts. In all cases, the reaction is carried out in a single reaction step. The best conversion is obtained when the catalyst is either sodium methoxide or potassium methoxide. We found that during the transesterification with ethanol, soap formation is more important than in the case of methanol. The saponification reaction consumes an important fraction of the catalyst. The amount of catalyst consumed by this reaction is 100% in the case of using hydroxides as catalyst (KOH or NaOH), and 25%, and 28% when using CH(3)ONa and CH(3)OK as catalysts, respectively. Ethanol increases the catalyst solubility in the oil-ethyl ester phase, thus accelerating the saponification reaction. It is possible to obtain high conversions in a one-step reaction, with a total glycerine concentration close to 0.25%. PMID:21339065

  6. Cholesteryl ester transfer between lipoproteins does not require a ternary tunnel complex with CETP.

    PubMed

    Lauer, Matthias E; Graff-Meyer, Alexandra; Rufer, Arne C; Maugeais, Cyrille; von der Mark, Elisabeth; Matile, Hugues; D'Arcy, Brigitte; Magg, Christine; Ringler, Philippe; Müller, Shirley A; Scherer, Sebastian; Dernick, Gregor; Thoma, Ralf; Hennig, Michael; Niesor, Eric J; Stahlberg, Henning

    2016-05-01

    The cholesteryl ester transfer protein (CETP) enables the transfer of cholesteryl ester (CE) from high-density lipoproteins (HDL) to low-density lipoproteins (LDL) in the plasma compartment. CETP inhibition raises plasma levels of HDL cholesterol; a ternary tunnel complex with CETP bridging HDL and LDL was suggested as a mechanism. Here, we test whether the inhibition of CETP tunnel complex formation is a promising approach to suppress CE transfer from HDL to LDL, for potential treatment of cardio-vascular disease (CVD). Three monoclonal antibodies against different epitopes of CETP are assayed for their potential to interfere with CE transfer between HDL and/or LDL. Surprisingly, antibodies that target the tips of the elongated CETP molecule, interaction sites sterically required to form the suggested transfer complexes, do not interfere with CETP activity, but an antibody binding to the central region does. We show that CETP interacts with HDL, but not with LDL. Our findings demonstrate that a ternary tunnel complex is not the mechanistic prerequisite to transfer CE among lipoproteins. PMID:26876146

  7. Surface components of chylomicrons from rats fed glyceryl or alkyl esters of fatty acids: minor components.

    PubMed

    Yang, L Y; Kuksis, A; Myher, J J; Pang, H

    1992-08-01

    The lipid class, fatty acid and molecular species composition of the minor polar surface components of rat lymph chylomicrons were determined during absorption of menhaden oil and corn oil or of the corresponding fatty acid ethyl esters. In addition to the previously reported minor polar lipids (sphingomyelin, phosphatidylserine, phosphatidylinositol, phosphatidic acid and lysophosphatidylcholine), we identified phosphatidylglycerol, dimethylphosphatidylethanolamine, ceramide and cholesteryl sulfate in the chylomicrons from both oil and ester feeding. The dietary fatty acids were found to be incorporated to a variable extent into the different phospholipid classes, the proportions of which remained the same during both types of feeding. No evidence was obtained for the presence of the minor glycerophospholipids characteristic of the lysosomal membranes (e.g., bis-phosphatidic, lysobisphosphatidic and semilysobis-phosphatidic acids), although special efforts were made to identify them. These results indicate that the chylomicrons arising from the monoacylglycerol and phosphatidic acid pathways of triacylglycerol biosynthesis become enveloped in closely similar monolayers of phospholipids. Hence, all triacylglycerols may be secreted from the villus cells via a common mechanism as suggested by the previously demonstrated convergence (at the 2-monoacylglycerol stage) of the monoacylglycerol and the phosphatidic acid pathways of mucosal triacylglycerol formation [Yang, Y.L., and Kuksis, A. (1991) J. Lipid Res. 32, 1173-1186]. PMID:1406072

  8. Chemical cross-linking with NHS esters: a systematic study on amino acid reactivities.

    PubMed

    Mädler, Stefanie; Bich, Claudia; Touboul, David; Zenobi, Renato

    2009-05-01

    Structure elucidation of tertiary or quaternary protein structures by chemical cross-linking and mass spectrometry (MS) has recently gained importance. To locate the cross-linker modification, dedicated software is applied to analyze the mass or tandem mass spectra (MS/MS). Such software requires information on target amino acids to limit the data analysis time. The most commonly used homobifunctional N-hydroxy succinimide (NHS) esters are often described as reactive exclusively towards primary amines, although side reactions with tyrosine and serine have been reported. Our goal was to systematically study the reactivity of NHS esters and derive some general rules for their attack of nucleophilic amino acid side chains in peptides. We therefore studied the cross-linking reactions of synthesized and commercial model peptides with disuccinimidyl suberate (DSS). The first reaction site in all cases was expectedly the alpha-NH(2)-group of the N-terminus or the epsilon-NH(2)-group of lysine. As soon as additional cross-linkers were attached or loops were formed, other amino acids were also involved in the reaction. In addition to the primary amino groups, serine, threonine and tyrosine showed significant reactivity due to the effect of neighboring amino acids by intermediate or permanent Type-1 cross-link formation. The reactivity is highly dependent on the pH and on adjacent amino acids. PMID:19132714

  9. The amphiphilic alkyl ester derivatives of l-ascorbic acid induce reorganization of phospholipid vesicles.

    PubMed

    Giudice, Francesca; Ambroggio, Ernesto E; Mottola, Milagro; Fanani, Maria Laura

    2016-09-01

    l-ascorbic acid alkyl esters (ASCn) are lipophilic forms of vitamin C, which maintain some of its antioxidant power. Those properties make this drug family attractive to be used in pharmacological preparations protecting other redox-sensible drugs or designed to reduce possible toxic oxidative processes. In this work, we tested the ability of l-ascorbic acid alkyl esters (ASCn) to modulate the structure, permeability, and rheological properties of phospholipid bilayers. The ASCn studied here (ASC16, ASC14, and ASC12) alter the structural integrity as well as the rheological properties of phospholipid membranes without showing any evident detergent activity. ASC14 appeared as the most efficient drug in destabilize the membrane structure of nano- and micro-size phospholipid liposomes inducing vesicle content leakage and shape elongation on giant unilamellar vesicles. It also was the most potent enhancer of membrane microviscosity and surface water structuring. Only ASC16 induced the formation of drug-enriched condensed domains after its incorporation into the lipid bilayer, while ASC12 appeared as the less membrane-disturbing compound, likely because of its poor, and more superficial, partition into the membrane. We also found that incorporation of ASCn into the lipid bilayers enhanced the reduction of membrane components, compared with soluble vitamin C. Our study shows that ASCn compounds, which vary in the length of the acyl chain, show different effects on phospholipid vesicles used as biomembrane models. Those variances may account for subtly differences in the effectiveness on their pharmacological applications. PMID:27342371

  10. Design, synthesis and biological evaluation of sugar-derived esters, [alpha]-ketoesters and [alpha]-ketoamides as inhibitors for Mycobacterium tuberculosis antigen 85C

    SciTech Connect

    Sanki, Aditya K.; Boucau, Julie; Umesiri, Francis E.; Ronning, Donald R.; Sucheck, Steven J.

    2010-08-16

    Peptide-based 1,2-dicarbonyl compounds have emerged as potent inhibitors for serine proteases. Herein, we have designed and synthesized D-arabinose and D-trehalose-based esters, {alpha}-ketoesters and {alpha}-ketoamides, and evaluated their inhibitory activity against Mycobacterium tuberculosis (Mtb) antigen 85C (ag85C), an acyltransferase in the serine hydrolase superfamily. In addition the compounds were evaluated for the ability to inhibit the growth of Mycobacterium smegmatis ATCC 14468, a non-pathogenic surrogate for Mtb. Among the synthetic analogs evaluated only the methyl ester1 derived from D-arabinose was found to inhibit the acyltransferase activity of ag85C (IC{sub 50} = 25 mM). Based on this weak inhibitory activity it was not surprising that none of the compounds inhibits the growth of M. smegmatis. In spite of the weak inhibitory activity of 1, X-ray crystallography on crystals of ag85C soaked with 1 suggested the formation of a covalent ester adduct between 1 and the Ser124 side chain hydroxyl moiety found within the catalytic site of ag85C; however, some of the active site electron density appears to result from bound glycerol. The lack of activity associated with the {alpha}-ketoester and {alpha}-ketoamide derivatives of D-trehalose may be the result of intramolecular cyclization of the {alpha}-keto moiety with the nearby C-4/4' hydroxyls leading to the formation of stable bicyclo-ester and amide derivatives.

  11. Cobalt carbonyl catalyzed reactions of esters and lactones with hydrosilane and carbon monoxide. A novel synthetic method for the introduction of the siloxymethylidene group

    SciTech Connect

    Chatani, N.; Fujii, S.; Yamasaki, Y.; Murai, S.; Sonoda, N.

    1986-11-12

    The catalytic reactions of esters and lactones with hydrosilane and carbon monoxide in the presence of Co/sub 2/(CO)/sub 8/ have been studied in detail with the emphasis being focused on their utility in organic synthesis. The catalytic reaction of secondary alkyl acetates underwent clean incorporation of carbon monoxide to give (siloxymethylidene)alkanes (enol silyl ethers). Lactones of secondary alkyl ester type reacted similarly. The siloxymethylidenation products were converted to aldehydes. Primary alkyl acetates gave several products in a nonselective manner. In the case of tertiary alkyl esters, no incorporation of carbon monoxide took place except for bridgehead alkyl acetates. The mechanism of the catalytic reaction has been proposed, and the importance of the silycobalt carbonyl, R/sub 3/SiCO(CO)/sub 4/, as the key catalyst species has been suggested. The high affinity of the silicon in R/sub 3/SiCo(CO)/sub 4/ toward the oxygen atom in the ester is suggested to be the driving force for the formation of alkylcobalt carbonyls as the intermediates. This step illustrates a new methodology for the formation of a carbon-transition metal bond.

  12. The transition from linear to highly branched poly(β-amino ester)s: Branching matters for gene delivery

    PubMed Central

    Zhou, Dezhong; Cutlar, Lara; Gao, Yongsheng; Wang, Wei; O’Keeffe-Ahern, Jonathan; McMahon, Sean; Duarte, Blanca; Larcher, Fernando; Rodriguez, Brian J.; Greiser, Udo; Wang, Wenxin

    2016-01-01

    Nonviral gene therapy holds great promise but has not delivered treatments for clinical application to date. Lack of safe and efficient gene delivery vectors is the major hurdle. Among nonviral gene delivery vectors, poly(β-amino ester)s are one of the most versatile candidates because of their wide monomer availability, high polymer flexibility, and superior gene transfection performance both in vitro and in vivo. However, to date, all research has been focused on vectors with a linear structure. A well-accepted view is that dendritic or branched polymers have greater potential as gene delivery vectors because of their three-dimensional structure and multiple terminal groups. Nevertheless, to date, the synthesis of dendritic or branched polymers has been proven to be a well-known challenge. We report the design and synthesis of highly branched poly(β-amino ester)s (HPAEs) via a one-pot “A2 + B3 + C2”–type Michael addition approach and evaluate their potential as gene delivery vectors. We find that the branched structure can significantly enhance the transfection efficiency of poly(β-amino ester)s: Up to an 8521-fold enhancement in transfection efficiency was observed across 12 cell types ranging from cell lines, primary cells, to stem cells, over their corresponding linear poly(β-amino ester)s (LPAEs) and the commercial transfection reagents polyethyleneimine, SuperFect, and Lipofectamine 2000. Moreover, we further demonstrate that HPAEs can correct genetic defects in vivo using a recessive dystrophic epidermolysis bullosa graft mouse model. Our findings prove that the A2 + B3 + C2 approach is highly generalizable and flexible for the design and synthesis of HPAEs, which cannot be achieved by the conventional polymerization approach; HPAEs are more efficient vectors in gene transfection than the corresponding LPAEs. This provides valuable insight into the development and applications of nonviral gene delivery and demonstrates great prospect for their

  13. Low Temperature Chlorine-Initiated Oxidation of Small-Chain Methyl Esters: Quantification of Chain-Terminating HO2-Elimination Channels.

    PubMed

    Muller, Giel; Scheer, Adam; Osborn, David L; Taatjes, Craig A; Meloni, Giovanni

    2016-03-17

    Cl-initiated oxidation reactions of three small-chain methyl esters, methyl propanoate (CH3CH2COOCH3; MP), methyl butanoate (CH3CH2CH2COOCH3; MB), and methyl valerate (CH3CH2CH2CH2COOCH3; MV), are studied at 1 or 8 Torr and 550 and 650 K. Products are monitored as a function of mass, time, and photoionization energy using multiplexed photoionization mass spectrometry coupled to tunable synchrotron photoionization radiation. Pulsed photolysis of molecular chlorine is the source of Cl radicals, which remove an H atom from the ester, forming a free radical. In each case, after addition of O2 to the initial radicals, chain-terminating HO2-elimination reactions are observed to be important. Branching ratios among competing HO2-elimination channels are determined via absolute photoionization spectra of the unsaturated methyl ester coproducts. At 550 K, HO2-elimination is observed to be selective, resulting in nearly exclusive production of the conjugated methyl ester coproducts, methyl propenoate, methyl-2-butenoate, and methyl-2-pentenoate, respectively. However, in MV, upon raising the temperature to 650 K, other HO2-elimination pathways are observed that yield methyl-3-pentenoate and methyl-4-pentenoate. In each methyl ester oxidation reaction, a peak is observed at a mass consistent with cyclic ether formation, indicating chain-propagating OH loss/ring formation pathways via QOOH intermediates. Evidence is observed for the participation of resonance-stabilized QOOH in the most prominent cyclic ether pathways. Stationary point energies for HO2-elimination pathways and select cyclic ether formation channels are calculated at the CBS-QB3 level of theory and assist in the assignment of reaction pathways and final products. PMID:26910881

  14. Improved Preparation of Halopropyl Bridged Carboxylic Ortho Esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Protection of a carboxylic acid function as a bridged ortho ester derivative enables the use of strongly basic conditions in the synthetic strategy because the protons, alpha to the previous carbonyl carbon, are less acidic. Protected 3-halopropionic acid can behave like an alkyl halide making them...

  15. Synthesis and physical properties of pennycress estolides and esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new series of pennycress (Thlasphi arvense L.) based free-acid estolides was synthesized by an acid-catalyzed condensation reaction, followed by an esterification reaction to produce the 2-ethylhexyl (2-EH) esters of the initial estolides. The physical properties of the estolides are highly affect...

  16. 21 CFR 556.240 - Estradiol and related esters.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Estradiol and related esters. 556.240 Section 556.240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD...

  17. 21 CFR 556.240 - Estradiol and related esters.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Estradiol and related esters. 556.240 Section 556.240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD...

  18. 21 CFR 556.240 - Estradiol and related esters.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Estradiol and related esters. 556.240 Section 556.240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS TOLERANCES FOR RESIDUES OF NEW ANIMAL DRUGS IN FOOD...

  19. Amidation of esters with amino alcohols using organobase catalysis.

    PubMed

    Caldwell, Nicola; Campbell, Peter S; Jamieson, Craig; Potjewyd, Frances; Simpson, Iain; Watson, Allan J B

    2014-10-01

    A catalytic protocol for the base-mediated amidation of unactivated esters with amino alcohol derivatives is reported. Investigations into mechanistic aspects of the process indicate that the reaction involves an initial transesterification, followed by an intramolecular rearrangement. The reaction is highly general in nature and can be extended to include the synthesis of oxazolidinone systems through use of dimethyl carbonate. PMID:25226088

  20. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN P-95-1128...) Recordkeeping. Recordkeeping requirements as specified in § 721.125 (a), (b), (c), (f), (g), (h), (i), and (k... Section 721.2925 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC...

  1. 40 CFR 721.2925 - Brominated aromatic ester.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reporting. (1) The chemical substance identified generically as a brominated aromatic ester (PMN P-95-1128...) Recordkeeping. Recordkeeping requirements as specified in § 721.125 (a), (b), (c), (f), (g), (h), (i), and (k... Section 721.2925 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC...

  2. 40 CFR 721.329 - Halogenated benzyl ester acrylate (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... halogenated benzyl ester acrylate (PMN P-90-1527) is subject to reporting under this section for the... processors of this substance as specified in § 721.125 (a), (b), (c), (d), (f), (g), (h), and (i). (2... substance may cause internal organ effects (kidney and blood). The requirements of this section do not...

  3. 21 CFR 172.859 - Sucrose fatty acid esters.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sucrose fatty acid esters. 172.859 Section 172.859 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives §...

  4. Interphase properties of carbon fiber-vinyl ester composites

    SciTech Connect

    Rich, M.J.; Weitzsacker, C.W.; Xie, M.; Corbin, S.; Drzal, L.T.

    1997-12-31

    The decline in price of carbon fibers gives an economic incentive to reconsider the use of these reinforcements in markets previously deemed too expensive, such as the automotive industry. Additionally, it would be advantageous if carbon fibers could be immediately used with polymers and manufacturing methods currently used for the production of fiberglass composites, and thus minimize development and startup costs. Of particular interest is the use of carbon fibers in vinyl esters manufactured by resin transfer molding, a leading manufacturing technology for the production of large and complex shaped composite parts. However, carbon fiber-vinyl ester composites have inferior mechanical properties as a result of poor bonding between fiber and matrix. The objective of this program was to evaluate the physical and chemical mechanisms currently thought responsible for adhesion in order to improve the performance of carbon fiber-vinyl ester composites. The effect of carbon fiber surface treatment on fiber chemistry and topography was evaluated to uncover the fundamental mechanisms governing carbon fiber to vinyl ester adhesion.

  5. 21 CFR 172.735 - Glycerol ester of rosin.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Glycerol ester of rosin. 172.735 Section 172.735 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Other Specific Usage Additives §...

  6. 21 CFR 172.735 - Glycerol ester of rosin.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Glycerol ester of rosin. 172.735 Section 172.735 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR...

  7. 21 CFR 172.735 - Glycerol ester of rosin.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Glycerol ester of rosin. 172.735 Section 172.735 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Other Specific Usage Additives §...

  8. Adsorption of diethyl phthalate ester to clay minerals.

    PubMed

    Wu, Yanhua; Si, Youbin; Zhou, Dongmei; Gao, Juan

    2015-01-01

    Phthalate esters are a group of plasticizers, which have been widely detected in China's agricultural and industrial soils. In this study, batch adsorption experiments were conducted to investigate the environmental effects on the adsorption of diethyl phthalate ester (DEP) to clay minerals. The results showed that DEP adsorption isotherms were well fitted with the Freundlich model; the interlayer spacing of K(+) saturated montmorillonite (K-mont) was the most important adsorption area for DEP, and di-n-butyl ester (DnBP) was limited to intercalate into the interlayer of K-mont due to the bigger molecular size; there was no significant effect of pH and ionic strength on DEP adsorption to K-mont/Ca-mont, but to Na-mont clay. The adsorption to kaolinite was very limited. Data of X-ray diffraction and FTIR spectra further proved that DEP molecules could intercalate into K-/Ca-mont interlayer, and might interact with clay through H-bonding between carbonyl groups and clay adsorbed water. Coated humic acid on clay surface would enhance DEP adsorption at low concentration, but not at high concentration (eg. Ce>0.26 mM). The calculated adsorption enthalpy (ΔHobs) and adsorption isotherms at varied temperatures showed that DEP could be adsorbed easier as more adsorbed. This study implied that clay type, compound structure, exchangeable cation, soil organic matter and temperature played important roles in phthalate ester's transport in soil. PMID:25150972

  9. Solvation of Esters and Ketones in Supercritical CO2.

    PubMed

    Kajiya, Daisuke; Imanishi, Masayoshi; Saitow, Ken-ichi

    2016-02-01

    Vibrational Raman spectra for the C═O stretching modes of three esters with different functional groups (methyl, a single phenyl, and two phenyl groups) were measured in supercritical carbon dioxide (scCO2). The results were compared with Raman spectra for three ketones involving the same functional groups, measured at the same thermodynamic states in scCO2. The peak frequencies of the Raman spectra of these six solute molecules were analyzed by decomposition into the attractive and repulsive energy components, based on the perturbed hard-sphere theory. For all solute molecules, the attractive energy is greater than the repulsive energy. In particular, a significant difference in the attractive energies of the ester-CO2 and ketone-CO2 systems was observed when the methyl group is attached to the ester or ketone. This difference was significantly reduced in the solute systems with a single phenyl group and was completely absent in those with two phenyl groups. The optimized structures among the solutes and CO2 molecules based on quantum chemical calculations indicate that greater attractive energy is obtained for a system where the oxygen atom of the ester is solvated by CO2 molecules. PMID:26741296

  10. Iodine-Catalyzed Synthesis of Mixed Cellulose Esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel method for the preparation of cellulose mixed acetate is described herein, involving the concurrent use of iodine and mixed anhydride. The method is simple, rapid, efficient, and solvent-less. With this method, cellulose mixed esters has been synthesized. ...

  11. Photoreactions of cyclic sulfite esters: Evidence for diradical intermediates

    PubMed Central

    Arney, Benny E; Ihmels, Heiko

    2012-01-01

    Summary The photochemistry of a phenyl and 1,2-diphenyl substituted sulfite ester is reported. The performance of photoreactions under relatively mild reaction conditions enables the detection of products that have not been observed in previous studies. It is concluded that, complementary to the initially proposed carbene intermediates, diradicals may also be considered. PMID:23019449

  12. Fungicidal Activities of Dihydroferulic Acid Alkyl Ester Analogues

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The natural product dihydroferulic acid (DFA, 1) and the synthesized DFA methyl (4a), ethyl (4b), propyl (4c), hexyl (4d), octyl (4e), and decyl (4f) esters were examined for antifungal activity. Test fungi included Saccharomyces cerevisiae (wild type, and deletion mutants slt2delta and bck1delta), ...

  13. Chemistry for Kids. Ester, What's in My Food?

    ERIC Educational Resources Information Center

    Clarke, Michele; And Others

    1986-01-01

    Describes three teaching activities used in the Chemistry for Kids program which focus on how esters are chemicals partially responsible for the flavor of foods. Includes a discussion of a demonstration involving role-playing, a set of taste tests, and an activity using chewing gum to investigate odors in food. (TW)

  14. [Exposure to vegetal esters based metal cutting fluids: health effects].

    PubMed

    Riva, M M; Bellini, M; Leghissa, P; Gambini, D; Mosconi, G

    2012-01-01

    The aim of our research is to study respiratory and dermatologic diseases (irritative and allergic) in a cohort of workers exposed to vegetal esters based metal cutting fluids of the latest generation. A cohort of 81 workers (mean age 34.5 years, seniority 17.4 years), with mean exposure to vegetal esters based metal cutting fluids of 2.8 years, has been subjected to clinical evaluations. The investigation did not reveal any disease or disorder of the respiratory system, any folluculitis or any allergic contact dermatitis caused by sensitization to vegetal esters based metal cutting fluids. On the contrary we documented 5 cases of irritant contact dermatitis, even if favored by an improper use of protection devices. According to early results, the introduction of vegetal esters based metal cutting fluids seems to reduce the risk to the worker's health. A longitudinal surveillance is still needed to confirm that even in the medium and long-term sensitizations will not occur. PMID:23405602

  15. A new multiflorane triterpenoid ester from Momordica cochinchinensis Spreng.

    PubMed

    De Shan, M; Hu, L H; Chen, Z L

    2001-01-01

    A new triterpenoid ester 3,29-di-O-(p-methoxy)benzoylmultiflora-8-ene-3 alpha,29-diol-7-one from the seeds of Momordica cochinchinensis Spreng has been isolated. Its structure was elucidated by spectroscopic evidence and confirmed by X-ray crystallography. PMID:11561447

  16. Improving Biodiesel Fuel Properties by Modifying Fatty Ester Composition

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiesel is an alternative to petroleum-derived diesel fuel composed of alkyl esters of vegetable oils, animal fats or other feedstocks such as used cooking oils. The fatty acid profile of biodiesel corresponds to that of its feedstock. Most feedstocks possess fatty acid profiles consisting mainl...

  17. Comparative assay of antioxidant packages for dimer of estolide esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of 26 different antioxidants and commercial antioxidant packages, containing both natural and synthetic-based materials, were evaluated with dimeric coconut-oleic estolide 2-ethylhexyl ester. The different antioxidants were broken down into different classes of materials: phenolic, aminic, ...

  18. 40 CFR 721.329 - Halogenated benzyl ester acrylate (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.329 Halogenated benzyl ester acrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  19. 40 CFR 721.329 - Halogenated benzyl ester acrylate (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.329 Halogenated benzyl ester acrylate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically...

  20. 40 CFR 721.4215 - Hexanedioic acid, diethenyl ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Hexanedioic acid, diethenyl ester. 721.4215 Section 721.4215 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4215 Hexanedioic...

  1. 40 CFR 721.5310 - Neononanoic acid, ethenyl ester.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Neononanoic acid, ethenyl ester. 721.5310 Section 721.5310 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.5310 Neononanoic...

  2. Preconcentration procedures for phthalate esters combined with chromatographic analysis.

    PubMed

    Lv, Xueju; Hao, Yi; Jia, Qiong

    2013-08-01

    Phthalate esters are endocrine disrupters or mutagens. They are widely used as plasticizers and can be usually found in environmental samples, such as food, soil and polluted air. However, it is difficult to directly determine phthalate esters owing to their relatively low concentration and complex matrices. Therefore, preconcentration and separation have become increasingly important. In recent years, many preconcentration methods have been successfully developed and widely used, such as liquid-liquid extraction, dispersive liquid-liquid microextraction and solid-phase extraction. These preconcentration methods for phthalate esters can be applied to various real samples, water, soil, air, food and cosmetics. The aim of this paper is to review recent literature studies (primarily from the last five years) about preconcentration techniques for phthalate esters coupled with chromatographic analysis. The following text describes several preconcentration approaches, including liquid-liquid extraction, dispersive liquid-liquid microextraction, cloud point extraction, solid-phase extraction, solid-phase microextraction and stir bar sorptive extraction. Their advantages and disadvantages are also summarized. PMID:23696389

  3. Combining Pear Ester with Codlemone Improves Management of Codling Moth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several management approaches utilizing pear ester combined with codlemone have been developed in the first 10 years after the discovery of this ripe pear fruit volatile’s kairomonal activity for larvae and both sexes of codling moth. These include a lure that consistently outperforms other high loa...

  4. Preparation of Jojoba Oil Ester Derivatives for Biodiesel Evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a result of the increase in commodity vegetable oil prices, it is imperative that non-food oils should be considered as alternative feedstocks for biodiesel production. Jojoba oil is unusual in that it is comprised of wax esters as opposed to the triglycerides found in typical vegetable oils. A...

  5. Fungicidal Activities of Dihydroferulic Acid Alkyl Ester Analogs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The natural product dihydroferulic acid (DFA, 1) and the synthesized DFA methyl (4a), ethyl (4b), propyl (4c), hexyl (4d), octyl (4e), and decyl (4f) esters were examined for antifungal activity. Test fungi included Saccharomyces cerevisiae (wild type, and deletion mutants slt2' and bck1'), Aspergil...

  6. Physical proprieties of low viscosity estolide 2-ethylhexyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Acetic- and butyric-capped oleic estolide 2-ethylhexyl (2-EH) esters were synthesized in a perchloric acid catalyzed (0.05 equiv) one-pot process from industrial 90% oleic acid and either acetic or butyric fatty acids at two different ratios. This was directly followed by the esterification process ...

  7. Novel triterpenoid acyl esters and alkaloids from Anoectochilus roxburghii.

    PubMed

    Han, Mei-Hua; Yang, Xiu-Wei; Jin, Yan-Ping

    2008-01-01

    Two novel sorghumol acyl esters, sorghumol 3-O-Z-p-coumarate and sorghumol 3-O-E-p-coumarate, and a novel alkaloid, anoectochine, were isolated from the whole plants of Anoectochilus roxburghii along with one known triterpenoid, sorghumol. Their structures were established by their detailed spectral studies, including two-dimensional NMR ((1)H-(1)H COSY, HSQC and HMBC). PMID:18435530

  8. Stability and friction reducing properties of epoxidized oleochemical methyl esters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of oleochemicals as biobased replacements for petrochemical lubricants is an important area of study. Physical properties of the epoxidized fatty esters derived from vegetable oil are reported and compared to their olefinic counterparts. Overall the frictional behavior of epoxy methyl olea...

  9. New triterpene esters from flowerheads of Arnica lonchophylla.

    PubMed

    Schmidt, Thomas J; von Raison, Jeanette; Willuhn, Günter

    2004-10-01

    From the flowerheads of Arnica lonchophylla Greene ssp. lonchophylla Maguire (Asteraceae), a variety of mono-, di- and trihydroxytriterpenes of the oleanane, ursane, lupane and dammarane types were isolated and their structures elucidated by EI and CI mass spectrometry and extensive NMR spectroscopic analysis. Most of the compounds are esterified at position 3 with lauric, myristic, palmitic and stearic acids. Several ester derivatives of known triterpenes represent new natural products. The triterpenetriols 20(30)-taraxasten-3beta,16beta,21alpha-triol (arnitriol A) and lupane-3beta,16beta,20-triol, both isolated in the form of their C3-fatty acid ester derivatives, possess hydroxylation patterns which have not been described previously. Besides small amounts of triterpenetriol esters, the lauric, myristic, palmitic and stearic acid esters of arnidiol, faradiol, maniladiol and calenduladiol were also identified in the flowerheads of A. montana (Arnicae flos Ph. Eur.), A. chamissonis ssp. foliosa and A. angustifolia ssp. attenuata. A search for sesquiterpene lactones in the flowers of A. lonchophylla resulted in the identification of small amounts of helenalin and 11alpha,13-dihydrohelenalin. PMID:15490326

  10. Continuous Production of Alkyl Esters Using an Immobilized Lipase Bioreactor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An immobilized lipase packed-bed bioreactor was developed for esterifying the free fatty acids in greases as a pretreatment step in the production of their simple alkyl esters for use as biodiesel. The immobilized lipases used in the study were immobilized preparations of Candida antarctica (C. a.)...

  11. 21 CFR 175.210 - Acrylate ester copolymer coating.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acrylate ester copolymer coating. 175.210 Section 175.210 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS...

  12. Development of Micro-Encapsulated Pear Ester Kairomone Spray Adjuvant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food Quality Protection Act 1996 is banning the use of most organophosphate (OP) insecticides and limitations on VOC-based products are being considered. Thus, there is a need for alternative insecticides to be made more effective and affordable. Knight and Light (2001) reported that the pear ester...

  13. VINYL-ESTER (VE) CURE CHARACTERIZATION VIA DIRECT CURRENT SENSORS

    EPA Science Inventory

    High-performance thermosetting composites typically consist of a high-modulus fibrous material embedded in a thermosetting polymer matrix. The behavior of the resulting composite depends on the properties of the reinforcement, the interphase, and the matrix. Vinyl-ester (VE) resi...

  14. Superhydrophobic surfaces fabricated from nano- and microstructured cellulose stearoyl esters.

    PubMed

    Geissler, Andreas; Chen, Longquan; Zhang, Kai; Bonaccurso, Elmar; Biesalski, Markus

    2013-05-28

    Robust, superhydrophobic and self-cleaning films were fabricated using nano- or microstructured cellulose fatty acid esters, which were prepared via nanoprecipitation. The superhydrophobic films could be coated on diverse surfaces with non-uniform shapes by distinct coating techniques. PMID:23609473

  15. 40 CFR 721.10498 - Substituted alkyl ester, hydrolysis products with silica (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Substituted alkyl ester, hydrolysis... Significant New Uses for Specific Chemical Substances § 721.10498 Substituted alkyl ester, hydrolysis products... chemical substances identified generically as substituted alkyl ester, hydrolysis products with...

  16. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  17. 40 CFR 721.10147 - Acrylate derivative of alkoxysilylalkane ester and mixed metal oxides (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... alkoxysilylalkane ester and mixed metal oxides (generic). 721.10147 Section 721.10147 Protection of Environment... alkoxysilylalkane ester and mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to... ester and mixed metal oxides (PMN P-07-198) is subject to reporting under this section for...

  18. Changes in Esters of Fatty Acids of Rhizopus arrhizus During Germination and Growth

    PubMed Central

    Hess, S. L.; Weber, D. J.; Gunasekaran, M.

    1972-01-01

    Natural esters of fatty acids of Rhizopus arrhizus Fischer increased during the first 48 hr of growth. During the 48- to 72-hr period, there was a shift in concentration from the methyl esters to the ethyl esters of fatty acids. PMID:5079078

  19. 21 CFR 175.260 - Partial phosphoric acid esters of polyester resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Partial phosphoric acid esters of polyester resins... of polyester resins. Partial phosphoric acid esters of polyester resins identified in this section... prescribed conditions: (a) For the purpose of this section, partial phosphoric acid esters of...

  20. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a...

  1. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Methyl glucoside-coconut oil ester. 172.816 Section... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is...

  2. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  3. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  4. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  5. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  6. 40 CFR 721.6110 - Alkyldi(alkyloxyhydroxypropyl) derivative, phosphoric acid esters, potassium salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) derivative, phosphoric acid esters, potassium salts. 721.6110 Section 721.6110 Protection of Environment...) derivative, phosphoric acid esters, potassium salts. (a) Chemical substance and significant new uses subject...) derivative, phosphoric acid esters, potassium salts (PMN P-91-818) is subject to reporting under this...

  7. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a...

  8. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methyl glucoside-coconut oil ester. 178.3600 Section 178.3600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester...

  9. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Methyl glucoside-coconut oil ester. 172.816... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is...

  10. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Methyl glucoside-coconut oil ester. 172.816... § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is the methyl glucoside-coconut oil...

  11. 21 CFR 172.816 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Methyl glucoside-coconut oil ester. 172.816... HUMAN CONSUMPTION Multipurpose Additives § 172.816 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester may be safely used in food in accordance with the following conditions: (a) It is...

  12. 21 CFR 178.3600 - Methyl glucoside-coconut oil ester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Methyl glucoside-coconut oil ester. 178.3600... SANITIZERS Certain Adjuvants and Production Aids § 178.3600 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil ester identified in § 172.816(a) of this chapter may be safely used as a...

  13. 40 CFR 721.10679 - Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... alkylstannylene ester, reaction products with inorganic acid tetra alkyl ester (generic). 721.10679 Section 721... SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10679 Carboxylic acid, substituted alkylstannylene ester, reaction products with inorganic acid tetra alkyl...

  14. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  15. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  16. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  17. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  18. 40 CFR 721.3800 - Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. 721.3800 Section 721.3800... Formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol, ethylene oxide adduct. (a... generically as formaldehyde, condensated polyoxyethylene fatty acid, ester with styrenated phenol,...

  19. 21 CFR 184.1101 - Diacetyl tartaric acid esters of mono- and diglycerides.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Diacetyl tartaric acid esters of mono- and... acid esters of mono- and diglycerides. (a) Diacetyl tartaric acid esters of mono- and diglycerides... groups of glycerin has been esterified by diacetyl tartaric acid and by fatty acids. The ingredient...

  20. 40 CFR 721.4250 - Hexanoic acid, 2-ethyl-, ethenyl ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hexanoic acid, 2-ethyl-, ethenyl ester... Substances § 721.4250 Hexanoic acid, 2-ethyl-, ethenyl ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as hexanoic acid, 2-ethyl-, ethenyl ester...

  1. 40 CFR 721.2900 - Substituted aminobenzoic acid ester (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted aminobenzoic acid ester... Specific Chemical Substances § 721.2900 Substituted aminobenzoic acid ester (generic name). (a) Chemical... acid ester (PMN P-84-951) is subject to reporting under this section for the significant new...

  2. 40 CFR 721.2900 - Substituted aminobenzoic acid ester (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Substituted aminobenzoic acid ester... Specific Chemical Substances § 721.2900 Substituted aminobenzoic acid ester (generic name). (a) Chemical... acid ester (PMN P-84-951) is subject to reporting under this section for the significant new...

  3. 40 CFR 721.10142 - Oxabicycloalkane carboxylic acid alkanediyl ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... alkanediyl ester (generic). 721.10142 Section 721.10142 Protection of Environment ENVIRONMENTAL PROTECTION... ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as oxabicycloalkane carboxylic acid alkanediyl ester (PMN P-06-199)...

  4. 40 CFR 180.1277 - Dibasic esters; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Dibasic esters; exemption from the... Exemptions From Tolerances § 180.1277 Dibasic esters; exemption from the requirement of a tolerance. Dibasic esters (CAS Reg. No. 95481-62-2) is exempted from the requirement of a tolerance for residues when...

  5. 40 CFR 721.2920 - tert-Amyl peroxy alkylene ester (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false tert-Amyl peroxy alkylene ester... Specific Chemical Substances § 721.2920 tert-Amyl peroxy alkylene ester (generic name). (a) Chemical... alkylene ester (PMN P-85-1180) is subject to reporting under this section for the significant new...

  6. 40 CFR 721.3063 - Substituted phenyl azo substituted phenyl esters (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... phenyl esters (generic name). 721.3063 Section 721.3063 Protection of Environment ENVIRONMENTAL... esters (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as substituted phenyl azo substituted phenyl esters (PMNs...

  7. 40 CFR 721.1579 - 1,2,4-Benzenetricarboxylic acid, tris [4-(ethenyloxy) butyl] ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ester. 721.1579 Section 721.1579 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.1579 1,2,4-Benzenetricarboxylic acid, tris ester. (a) Chemical substance...-benzenetricarboxylic acid, tris ester (PMN P-98-1165; CAS No. 196109-17-8) is subject to reporting under this...

  8. 40 CFR 180.1222 - Sucrose octanoate esters; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Sucrose octanoate esters; exemption... FOOD Exemptions From Tolerances § 180.1222 Sucrose octanoate esters; exemption from the requirement of... octanoate esters in or on all food commodities when used in accordance with good agricultural practices....

  9. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ester with pentaerythritol. 721.3680 Section 721.3680 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  10. 40 CFR 721.10133 - 2-Propenoic acid, 2-methyl, 2-hydroxyethyl ester, homopolymer.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-hydroxyethyl ester, homopolymer. 721.10133 Section 721.10133 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10133 2-Propenoic acid, 2-methyl, 2-hydroxyethyl ester... identified as 2-propenoic acid, 2-methyl, 2-hydroxyethyl ester, homopolymer (PMN P-07-401; CAS No....

  11. 40 CFR 721.7290 - Propanoic acid, 2-(trimethoxysilyl)-, ethyl ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...)-, ethyl ester. 721.7290 Section 721.7290 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7290 Propanoic acid, 2-(trimethoxysilyl)-, ethyl ester. (a) Chemical... acid, 2-(trimethoxysilyl)-, ethyl ester (PMN P-01-22; CAS No. 137787-41-8) is subject to...

  12. 40 CFR 721.8340 - Mono esters from 2- propenoic acid (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mono esters from 2- propenoic acid... Specific Chemical Substances § 721.8340 Mono esters from 2- propenoic acid (generic). (a) Chemical... as mono esters from 2-propenoic acid (PMN P-01-85) is subject to reporting under this section for...

  13. 40 CFR 180.1277 - Dibasic esters; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Dibasic esters; exemption from the... Exemptions From Tolerances § 180.1277 Dibasic esters; exemption from the requirement of a tolerance. Dibasic esters (CAS Reg. No. 95481-62-2) is exempted from the requirement of a tolerance for residues when...

  14. 40 CFR 721.1579 - 1,2,4-Benzenetricarboxylic acid, tris [4-(ethenyloxy) butyl] ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ester. 721.1579 Section 721.1579 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.1579 1,2,4-Benzenetricarboxylic acid, tris ester. (a) Chemical substance...-benzenetricarboxylic acid, tris ester (PMN P-98-1165; CAS No. 196109-17-8) is subject to reporting under this...

  15. 40 CFR 721.10165 - Carbonotrithioic acid, bis(phenylmethyl) ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...(phenylmethyl) ester. 721.10165 Section 721.10165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10165 Carbonotrithioic acid, bis(phenylmethyl) ester. (a) Chemical... carbonotrithioic acid, bis(phenylmethyl) ester (PMN P-08-138; CAS No.26504-29-0) is subject to reporting under...

  16. 40 CFR 721.6475 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Alkyl polycarboxylic acids, esters... Significant New Uses for Specific Chemical Substances § 721.6475 Alkyl polycarboxylic acids, esters with... chemical substances identified generically as alkyl polycarboxylic acids, esters with ethoxylated...

  17. 40 CFR 721.3063 - Substituted phenyl azo substituted phenyl esters (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... phenyl esters (generic name). 721.3063 Section 721.3063 Protection of Environment ENVIRONMENTAL... esters (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substances identified generically as substituted phenyl azo substituted phenyl esters (PMNs...

  18. 40 CFR 721.9965 - Fatty acids, C10-13 - branched, vinyl esters.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... esters. 721.9965 Section 721.9965 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.9965 Fatty acids, C10-13 - branched, vinyl esters. (a) Chemical... acids, C10-13 - branched, vinyl esters (PMN P-97-482; CAS No. 184785-38-4) is subject to reporting...

  19. 40 CFR 721.3680 - Ethylene oxide adduct of fatty acid ester with pentaerythritol.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ester with pentaerythritol. 721.3680 Section 721.3680 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.3680 Ethylene oxide adduct of fatty acid ester with... identified generically as ethylene oxide adduct of fatty acid ester with pentaerythritol (PMN P-91-442)...

  20. 40 CFR 721.1577 - 1,4-Benzenedicarboxylic acid, bis [4-(ethenyloxy) butyl] ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ester. 721.1577 Section 721.1577 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.1577 1,4-Benzenedicarboxylic acid, bis ester. (a) Chemical substance and... acid, bis ester (PMN P-98-1163; CAS No. 117397-31-6) is subject to reporting under this section for...

  1. 40 CFR 721.7290 - Propanoic acid, 2-(trimethoxysilyl)-, ethyl ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...)-, ethyl ester. 721.7290 Section 721.7290 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.7290 Propanoic acid, 2-(trimethoxysilyl)-, ethyl ester. (a) Chemical... acid, 2-(trimethoxysilyl)-, ethyl ester (PMN P-01-22; CAS No. 137787-41-8) is subject to...

  2. 40 CFR 721.10142 - Oxabicycloalkane carboxylic acid alkanediyl ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... alkanediyl ester (generic). 721.10142 Section 721.10142 Protection of Environment ENVIRONMENTAL PROTECTION... ester (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as oxabicycloalkane carboxylic acid alkanediyl ester (PMN P-06-199)...

  3. 40 CFR 721.1577 - 1,4-Benzenedicarboxylic acid, bis [4-(ethenyloxy) butyl] ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ester. 721.1577 Section 721.1577 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.1577 1,4-Benzenedicarboxylic acid, bis ester. (a) Chemical substance and... acid, bis ester (PMN P-98-1163; CAS No. 117397-31-6) is subject to reporting under this section for...

  4. 40 CFR 180.1222 - Sucrose octanoate esters; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Sucrose octanoate esters; exemption... FOOD Exemptions From Tolerances § 180.1222 Sucrose octanoate esters; exemption from the requirement of... octanoate esters in or on all food commodities when used in accordance with good agricultural practices....

  5. 40 CFR 721.8340 - Mono esters from 2- propenoic acid (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mono esters from 2- propenoic acid... Specific Chemical Substances § 721.8340 Mono esters from 2- propenoic acid (generic). (a) Chemical... as mono esters from 2-propenoic acid (PMN P-01-85) is subject to reporting under this section for...

  6. 40 CFR 721.6475 - Alkyl polycarboxylic acids, esters with ethoxylated fatty alcohols.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl polycarboxylic acids, esters... Significant New Uses for Specific Chemical Substances § 721.6475 Alkyl polycarboxylic acids, esters with... chemical substances identified generically as alkyl polycarboxylic acids, esters with ethoxylated...

  7. 40 CFR 721.9965 - Fatty acids, C10-13 - branched, vinyl esters.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... esters. 721.9965 Section 721.9965 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Specific Chemical Substances § 721.9965 Fatty acids, C10-13 - branched, vinyl esters. (a) Chemical... acids, C10-13 - branched, vinyl esters (PMN P-97-482; CAS No. 184785-38-4) is subject to reporting...

  8. 40 CFR 721.6075 - Phosphonic acid, 1,1-methylenebis-tetrakis(1-methylethyl) ester.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-tetrakis(1-methylethyl) ester. 721.6075 Section 721.6075 Protection of Environment ENVIRONMENTAL PROTECTION...-methylethyl) ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as phosphonic acid, 1,1-methylenebis-tetrakis(1-methylethyl) ester (PMN P-95-168)...

  9. 40 CFR 721.987 - Dialkylaminophenyl imino pyrazole acid ester (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ester (generic). 721.987 Section 721.987 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.987 Dialkylaminophenyl imino pyrazole acid ester (generic). (a) Chemical... as dialkylaminophenyl imino pyrazole acid ester (PMN P-98-45) is subject to reporting under...

  10. 40 CFR 721.10133 - 2-Propenoic acid, 2-methyl, 2-hydroxyethyl ester, homopolymer.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-hydroxyethyl ester, homopolymer. 721.10133 Section 721.10133 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10133 2-Propenoic acid, 2-methyl, 2-hydroxyethyl ester... identified as 2-propenoic acid, 2-methyl, 2-hydroxyethyl ester, homopolymer (PMN P-07-401; CAS No....

  11. 40 CFR 721.10165 - Carbonotrithioic acid, bis(phenylmethyl) ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...(phenylmethyl) ester. 721.10165 Section 721.10165 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10165 Carbonotrithioic acid, bis(phenylmethyl) ester. (a) Chemical... carbonotrithioic acid, bis(phenylmethyl) ester (PMN P-08-138; CAS No.26504-29-0) is subject to reporting under...

  12. 40 CFR 721.987 - Dialkylaminophenyl imino pyrazole acid ester (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... ester (generic). 721.987 Section 721.987 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.987 Dialkylaminophenyl imino pyrazole acid ester (generic). (a) Chemical... as dialkylaminophenyl imino pyrazole acid ester (PMN P-98-45) is subject to reporting under...

  13. 40 CFR 721.6075 - Phosphonic acid, 1,1-methylenebis-tetrakis(1-methylethyl) ester.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-tetrakis(1-methylethyl) ester. 721.6075 Section 721.6075 Protection of Environment ENVIRONMENTAL PROTECTION...-methylethyl) ester. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as phosphonic acid, 1,1-methylenebis-tetrakis(1-methylethyl) ester (PMN P-95-168)...

  14. 40 CFR 721.2920 - tert-Amyl peroxy alkylene ester (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false tert-Amyl peroxy alkylene ester... Specific Chemical Substances § 721.2920 tert-Amyl peroxy alkylene ester (generic name). (a) Chemical... alkylene ester (PMN P-85-1180) is subject to reporting under this section for the significant new...

  15. 40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... aliphatic polyol dihydrogen phosphate aromatic ester (generic). 721.10289 Section 721.10289 Protection of... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject...

  16. 40 CFR 721.10548 - Mixed alkyl phosphate esters alkoxylated (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed alkyl phosphate esters... Specific Chemical Substances § 721.10548 Mixed alkyl phosphate esters alkoxylated (generic). (a) Chemical... as mixed alkyl phosphate esters alkoxylated (PMN P-04-624) is subject to reporting under this...

  17. 40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... aliphatic polyol dihydrogen phosphate aromatic ester (generic). 721.10289 Section 721.10289 Protection of... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject...

  18. 40 CFR 721.10548 - Mixed alkyl phosphate esters alkoxylated (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed alkyl phosphate esters... Specific Chemical Substances § 721.10548 Mixed alkyl phosphate esters alkoxylated (generic). (a) Chemical... as mixed alkyl phosphate esters alkoxylated (PMN P-04-624) is subject to reporting under this...

  19. 40 CFR 721.10289 - Hexanedioic acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... aliphatic polyol dihydrogen phosphate aromatic ester (generic). 721.10289 Section 721.10289 Protection of... polymer with aliphatic polyol dihydrogen phosphate aromatic ester (generic). (a) Chemical substance and... acid polymer with aliphatic polyol dihydrogen phosphate aromatic ester (PMN P-11-333) is subject...

  20. 40 CFR 721.10223 - Styrenyl surface treated manganese ferrite with acrylic ester polymer (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... ferrite with acrylic ester polymer (generic). 721.10223 Section 721.10223 Protection of Environment... manganese ferrite with acrylic ester polymer (generic). (a) Chemical substance and significant new uses... manganese ferrite with acrylic ester polymer (PMN P-09-582) is subject to reporting under this section...