- Design of well balanced hydrophilic-lipophilic catalytic surfaces for the direct and selective monoesterification of various polyols
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The transesterification process is a well known reaction of organic chemistry. However, the monoesterification of unprotected polyols such as glycerol or sucrose is much more complex and the design of selective catalysts is becoming a huge challenge in order to avoid many protection and deprotection steps, harmful for the cost and the environmental impact of the resulting process. In this study, we showed that the control of the hydrophilic-lipophilic balance of heterogeneous catalysts is a crucial key in order to tune both the catalyst activity and the monoester selectivity. Indeed, whereas homogeneous guanidine led to low selectivity toward monoesters, its anchorage on a hydrophilic solid support such as silica allowed us to prepare two basic hybrid organic-inorganic materials able to selectively afford monoesters in high yield and in an environmentally-friendly process, at low temperature and starting from an equimolecular mixture of unprotected polyols and various fatty methyl esters. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.
- Kharchafi, Ghizlane,Jerome, Francois,Adam, Isabelle,Pouilloux, Yannick,Barrault, Joel
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- Discovery of FAHFA-Containing Triacylglycerols and Their Metabolic Regulation
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FAHFAs are a class of bioactive lipids, which show great promise for treating diabetes and inflammatory diseases. Deciphering the metabolic pathways that regulate endogenous FAHFA levels is critical for developing diagnostic and therapeutic strategies. However, it remains unclear how FAHFAs are metabolized in cells or tissues. Here, we investigate whether FAHFAs can be incorporated into other lipid classes and identify a novel class of endogenous lipids, FAHFA-containing triacylglycerols (FAHFA-TGs), which contain a FAHFA group esterified to the glycerol backbone. Isotope-labeled FAHFAs are incorporated into FAHFA-TGs when added to differentiated adipocytes, which implies the existence of enzymes and metabolic pathways capable of synthesizing these lipids. Induction of lipolysis (i.e., triacylglycerol hydrolysis) in adipocytes is associated with marked increases in nonesterified FAHFA levels, demonstrating that FAHFA-TGs breakdown is a regulator of cellular FAHFA levels. To quantify FAHFA levels in FAHFA-TGs and determine their regioisomeric distributions, we developed a mild alkaline hydrolysis method that liberates FAHFAs from triacylglycerols for easier detection. FAHFA-TG concentrations are greater than 100-fold than that of nonesterified FAHFAs, indicating that FAHFA-TGs are a major reservoir of FAHFAs in cells and tissues. The discovery of FAHFA-TGs reveals a new branch of TG and FAHFA metabolism with potential roles in metabolic health and regulation of inflammation.
- Tan, Dan,Ertunc, Meric Erikci,Konduri, Srihari,Zhang, Justin,Pinto, Antonio M.,Chu, Qian,Kahn, Barbara B.,Siegel, Dionicio,Saghatelian, Alan
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- 13C NMR quantification of mono and diacylglycerols obtained through the solvent-free lipase-catalyzed esterification of saturated fatty acids
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In the present investigation, we studied the enzymatic synthesis of monoacylglycerols (MAG) and diacylglycerols (DAG) via the esterification of saturated fatty acids (stearic, palmitic and an industrial residue containing 87% palmitic acid) and glycerol in a solvent-free system. Three immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym 435) and different reaction conditions were evaluated. Under the optimal reaction conditions, esterifications catalyzed by Lipozyme RM IM resulted in a mixture of MAG and DAG at high conversion rates for all of the substrates. In addition, except for the reaction of industrial residue at atmospheric pressure, all of these products met the World Health Organization and European Union directives for acylglycerol mixtures for use in food applications. The products were quantified by 13C NMR, with the aid of an external reference signal which was generated from a sealed coaxial tube filled with acetonitrile-d3. After calibrating the area of this signal using the classical external reference method, the same coaxial tube was used repeatedly to quantify the reaction products. Copyright
- Fernandes, Jane Luiza Nogueira,De Souza, Rodrigo Octavio Mendonca Alves,De Vasconcellos Azeredo, Rodrigo Bagueira
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experimental part
p. 424 - 428
(2012/08/14)
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- Interesterification Kinetics of Triglycerides and Fatty Acids with Modified Lipase in n-Hexane
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The kinetics of lipase-catalyzed interesterification of triglycerides and fatty acids in organic media was studied.First, the lipase Saiken 100, Rhizopus japonicus, was modified by surfactant to form an enzyme precipitate in aqueous solution, which was well dispersed in organic solvents.This modified lipase catalyzed the interesterification of tripalmitin and stearic acid.The enzyme has 1,3-positional specificity and does not distinguish between stearic and palmitic acids.The kinetic model developed to describe the interesterification reaction system is based on mass balance of two consecutive second-order reversible reactions.The reaction rate constant, k, was determined by solving the differential rate equations of the reaction system and by expressing the value of k as a function of concentrations of the substrates with time.The model gave satisfactory results.The best value of the specific reaction rate constant k* that fits all experimental data was 1.2*10-5 2/(mmol*mg biocatalyst*h)> under the reaction conditions in this study. Key words: Acidolysis, biocatalyst, fatty acids, interesterification kinetics, modified lipase, palmitic acid, reaction rate constant, stearic acid, triglycerides.
- Basheer, Sobhi,Mogi, Ken-ichi,Nakajima, Mitsutoshi
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p. 511 - 518
(2007/10/02)
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- A CONVENIENT PREPARATION OF 1,2-DIACYLGLYCEROLS; o-IODOBENZOYL AS A PROTECTING GROUP
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The o-iodobenzoyl moiety is a useful 3-hydroxyl protecting group in the synthesis of 1,2-diacylglycerols; it can be removed by chlorination followed by mild basic hydrolysis.
- Moss, Robert A.,Scrimin, Paolo,Bhattacharya, Santanu,Chatterjee, Swati
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p. 5005 - 5008
(2007/10/02)
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