The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Jacek Stawinski - One of the best experts on this subject based on the ideXlab platform.
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regioselective and stereospecific acylation across oxirane and silyloxy systems as a novel strategy to the synthesis of enantiomerically pure mono di and triglycerides
Organic and Biomolecular Chemistry, 2007Co-Authors: Stephan D Stamatov, Jacek StawinskiAbstract:A trifluoroacetate-catalyzed opening of the oxirane ring of glycidyl derivatives bearing allylic acyl or alkyl functionalities with trifluoroacetic anhydride (TFAA), provides an efficient entry to configurationally homogeneous 1(3)-acyl- or 1(3)-O-alkyl-sn-Glycerols. Selective introduction of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl- (TIPS) transient protections at the terminal sites within these key intermediates secures 1(3)-acyl- or 1(3)-O-alkyl-3(1)-O-TBDMS (or TIPS)-sn-Glycerols as general bifunctional precursors to 1,2(2,3)-diacyl-, 1(3)-O-alkyl-2-acyl- and 1,3-diacyl-sn-Glycerols and hence triester isosters. Incorporation of a requisite acyl residue at the central carbon of the silylated synthons with a subsequent Et3N·3HF-promoted, direct trichloroacetylation across the siloxy system by trichloroacetic anhydride (TCAA), followed by cleavage of the trichloroacetyl group, affords the respective 1,2(2,3)-diacyl- or 1(3)-O-alkyl-2-acyl-sn-Glycerols. Alternatively, a reaction sequence involving: (i) attachment of a trichloroacetyl fragment at the stereogenic C2-centre of the monosilylated glycerides; (ii) replacement of the silyl moiety by a short- or long-chain carboxylic acid residue by means of the acylating agent: tetra-n-butylammonium bromide (TBABr)–carboxylic acid anhydride (CAA)–trimethylsilyl bromide (TMSBr); and (iii) removal of the trichloroacetyl replacement, provides pure 1,3-diacyl-sn-Glycerols. The TBABr–CAA–TMSBr reagent system allows also a one-step conversion of 1,2-diacylglycerol silyl ethers into homochiral triglycerides with predefined asymmetry and degree of unsaturation. These compounds can also be accessed via a two-step one-pot approach where the trichloroacetyl derivatives of 1,2(2,3)- or 1,3-diacyl-sn-Glycerols serve as triester building blocks for establishing the third ester bond at preselected C3(1)- or C2-positions within the glycerol skeleton at the very last synthetic stage. In all instances, the target compounds were produced under mild conditions, in high enantiomeric purity, and in practically quantitative yields.
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a direct transformation of o silyl groups into o trichloroacetates a novel synthetic approach to protein kinase c ligands 1 oleoyl 2 acetyl and 1 hexadecyl 2 acetyl sn Glycerols
Tetrahedron Letters, 2005Co-Authors: Stephan D Stamatov, Martin Kullberg, Jacek StawinskiAbstract:A fluoride ion-promoted direct esterification of tert-butyldimethylsilyl- (TBDMS), or triisopropylsilyl (TIPS)-protected glycerol derivatives by means of trichloroacetic anhydride (TCAA), followed by removal of the trichloroacetyl transient protection, provides a new, efficient entry to stereochemically pure 1-oleoyl-2-acetyl- and 1-O-hexadecyl-2-acetyl-sn-Glycerols.
Albin Hermetter - One of the best experts on this subject based on the ideXlab platform.
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new fluorogenic triacylglycerol analogs as substrates for the determination and chiral discrimination of lipase activities
Journal of Lipid Research, 1996Co-Authors: M Duque, M Graupner, H Stutz, Iris Wicher, Rudolf Zechner, Fritz Paltauf, Albin HermetterAbstract:A new type of fluorogenic and isomerically pure 1(3)-0alkyl-2,3 (3,2)diacyl Glycerols was synthesized that can be used as substrate for the determination of lipase activities. These compounds contain a fluorescent pyrene acyl chain and, as a potent quencher of pyrene fluorescence, a trini- trophenylamino acyl residue. In their intact form, the fluoro- gens show only low fluorescence intensity. Upon lipase-in- duced or chemical hydrolysis of the substrates, however, the fluorophore and quencher separate from each other. This leads to a gradual increase in pyrene fluorescence, reflecting the time-dependent progress of lipolysis and, under substrate saturation conditions, lipase activity. This lipase assay is con- tinuous and does not require separation of substrate and reaction products. Short- and long-chain homologues as well as optical isomers of the fluorogenic alkyldiacyl Glycerols were hydrolyzed by pancreatic lipase, hepatic lipase, and lipo- protein lipase at highly different rates depending on the substrate or enzyme preparation and source (e.g., postheparin plasma or cultured cells).l It is proposed that a useful set of enantiomeric and/or homologous substrates in combina- tion with appropriate reaction media might be applied to the selective determination of a lipase in a mixture of lipases, e.g., hepatic and lipoprotein lipase in PHP, for medical diagnos- tics.-Duque, M., M. Graupner, H. Stiitz, I. Wicher, R. Zech- ner, F. Paltauf, and A. Hermetter. New fluorogenic triacyl- glycerol analogs as substrates for the determination and chid discrimination of lipase activities.). Lzpid Res. 1996. 37: 868-876. Supplementary key words hepatic lipase pancreatic lipase lipo- protein lipase 0 fluorescent lipids albumin-lipid complex lipase assay alkyldiacyl Glycerols pyrene-glycerolipids post-heparin plasma glycerolipid synthesis stereoselectivity
Angelo Fontana - One of the best experts on this subject based on the ideXlab platform.
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glycolipids synthesis improved hydrazinolysis conditions for preparation of 1 2 polyunsaturated fatty acyl β monogalactosyl Glycerols
Carbohydrate Research, 2016Co-Authors: Dario Pagano, Adele Cutignano, Emiliano Manzo, Francesco Tinto, Angelo FontanaAbstract:The investigation is related to the development of a general strategy for the synthesis of glycolipids including analogs bearing polyunsaturated fatty acids. In particular, here we report exceptionally mild and selective conditions to remove acetate protecting groups from glyceroglycolipids by hydrazinolysis. Synthetic 1,2-O-di-arachidonoyl-3-O-β-galactosyl-glycerol was used as representative of polyunsaturated β-galactosyl-di-acyl-Glycerols due to its reactivity under the conditions usually employed in literature.
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regioselective synthesis of diterpenoid 1 2 diacyl sn glycerides
Tetrahedron Letters, 1997Co-Authors: Angelo Fontana, Nicon Ungur, Margherita Gavagnin, Ciro Salierno, Guido CiminoAbstract:Abstract The regioselective synthesis of optically active 1-diterpenoid acyl-2-acetyl- sn -Glycerols is reported. The products are obtained by acylation of 2,3-isopropylidene- sn -glycerol. The key reaction is the deprotection of 1,2-diacyl-3-TBDMS- sn -glycerides by lewis acid based treatment with PdCl 2 (CH 3 CN) 2 in acetone.
Tibor Harkany - One of the best experts on this subject based on the ideXlab platform.
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Targeted Lipidomics in Drosophila melanogaster Identifies Novel 2-MonoacylGlycerols and N-acyl Amides
2016Co-Authors: On P. Rhodes, Sara M Takacs, Arjun Basnet, Siham Raboune, Theodore S Widlanski, Patrick Doherty, Tibor Harkany, Jordyn M. Stuart, Heather B. BradshawAbstract:Lipid metabolism is critical to coordinate organ development and physiology in response to tissue-autonomous signals and environmental cues. Changes to the availability and signaling of lipid mediators can limit competitiveness, adaptation to environmental stressors, and augment pathological processes. Two classes of lipids, the N-acyl amides and the 2-acyl Glycerols, have emerged as important signaling molecules in a wide range of species with important signaling properties, though most of what is known about their cellular functions is from mammalian models. Therefore, expanding available knowledge on the repertoire of these lipids in invertebrates will provide additional avenues of research aimed at elucidating biosynthetic, metabolic, and signaling properties of these molecules. Drosophila melanogaster is a commonly used organism to study intercellular communication, including the functions of bioactive lipids. However, limited information is available on the molecular identity of lipids with putative biological activities in Drosophila. Here, we used a targeted lipidomics approach to identify putative signaling lipids in third instar Drosophila larvae, possessing particularly large lipid mass in their fat body. We identified 2-linoleoyl glycerol, 2-oleoyl glycerol, and 45 N-acyl amides in larval tissues, and validated our findings by the comparative analysis of Oregon-RS, Canton-S and w1118 strains. Data here suggest that Drosophil
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targeted lipidomics in drosophila melanogaster identifies novel 2 monoacylGlycerols and n acyl amides
PLOS ONE, 2013Co-Authors: Giuseppe Tortoriello, Brandon Rhodes, Sara M Takacs, Jordyn Stuart, Arjun Basnet, Siham Raboune, Theodore S Widlanski, Patrick Doherty, Tibor HarkanyAbstract:Lipid metabolism is critical to coordinate organ development and physiology in response to tissue-autonomous signals and environmental cues. Changes to the availability and signaling of lipid mediators can limit competitiveness, adaptation to environmental stressors, and augment pathological processes. Two classes of lipids, the N-acyl amides and the 2-acyl Glycerols, have emerged as important signaling molecules in a wide range of species with important signaling properties, though most of what is known about their cellular functions is from mammalian models. Therefore, expanding available knowledge on the repertoire of these lipids in invertebrates will provide additional avenues of research aimed at elucidating biosynthetic, metabolic, and signaling properties of these molecules. Drosophila melanogaster is a commonly used organism to study intercellular communication, including the functions of bioactive lipids. However, limited information is available on the molecular identity of lipids with putative biological activities in Drosophila. Here, we used a targeted lipidomics approach to identify putative signaling lipids in third instar Drosophila larvae, possessing particularly large lipid mass in their fat body. We identified 2-linoleoyl glycerol, 2-oleoyl glycerol, and 45 N-acyl amides in larval tissues, and validated our findings by the comparative analysis of Oregon-RS, Canton-S and w1118 strains. Data here suggest that Drosophila represent another model system to use for the study of 2-acyl glycerol and N-acyl amide signaling.
David Ohagan - One of the best experts on this subject based on the ideXlab platform.
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incorporation of 2h1 1r 2r and 2h1 1s 2r Glycerols into the antibiotic nucleocidin in streptomyces calvus
Organic and Biomolecular Chemistry, 2017Co-Authors: Xuan Feng, Nawaf Al Maharik, Axel Bartholome, Jeffrey E Janso, Usa Reilly, David OhaganAbstract:Deuterium incorporations from [2H1]-(1R,2R) and [2H1]-(1S,2R) Glycerols into the fluorine containing antibiotic nucleocidin, in Streptomyces calvus indicate that one deuterium atom is incorporated at the C-5′ site of nucleocidin from each of these isotopomers of glycerol. Two deuteriums become incorporated at C-5′ of nucleocidin after a feeding experiment with [2H5]-glycerol. These observations indicate that there is no obligate oxidation of the pro-R hydroxymethyl group of glycerol as it progresses through the pentose phosphate pathway and becomes incorporated into the fluorinated antibiotic.