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ABSTRACT: A convergent synthesis of an isosteric phosphonic acid analogue of phosphatidylinositol has been accomplished in which a non-hydrolyzable P—C—C linkage is present in place of the normal P—O—C esteric linkage joining the phosphate and diacylglycerol portions of the molecule. The synthetic route used provides the configuration at each stereogenic center to correspond to that present in the biologically generated phospholipid. In addition, the approach provides asymmetric introduction of acyl functions, placing saturated and unsaturated acyl groups in the terminal and internal positions respectively of the backbone portion of the analogue, corresponding to that present in the biologically generated phospholipid.
Canadian Journal of Chemistry 02/2011; 70(8):2135-2141. · 1.24 Impact Factor
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ABSTRACT: A phosphonic acid analogue of platelet activating factor (PAF) bearing a backbone that is isosteric with and has stereochemistry corresponding to that of natural PAF has been synthesized. The synthesis uses a route maintaining stereochemical integrity.
Canadian Journal of Chemistry 02/2011; 71(2):206-209. · 1.24 Impact Factor
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Robert Engel,
Ishrat Ghani,
Diego Montenegro,
Marie Thomas,
Barbara Klaritch-Vrana,
Alejandra Castaño,
Laura Friedman,
Jay Leb,
Leah Rothman,
Heidi Lee,
Craig Capodiferro,
Daniel Ambinder,
Eva Cere,
Christopher Awad,
Faiza Sheikh,
Jaimelee Rizzo,
Lisa-Marie Nesbitt,
Erika Testani,
Karin Melkonian
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ABSTRACT: Cationic lipids have long been known to serve as antibacterial and antifungal agents. Prior efforts with attachment of cationic lipids to carbohydrate-based surfaces have suggested the possibility that carbohydrate-attached cationic lipids might serve as antibacterial and antifungal pharmaceutical agents. Toward the understanding of this possibility, we have synthesized several series of cationic lipids attached to a variety of glycosides with the intent of generating antimicrobial agents that would meet the requirement for serving as a pharmaceutical agent, specifically that the agent be effective at a very low concentration as well as being biodegradable within the organism being treated. The initial results of our approach to this goal are presented.
Molecules 01/2011; 16(2):1508-18. · 2.39 Impact Factor
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ABSTRACT: A new solid-phase microextraction (SPME) procedure using an ionic liquid (IL) has been developed. Reusable IL-based SPME fiber was prepared for the first time by fixing IL through cross-linkage of IL impregnated silicone elastomer on the surface of a fused silica fiber. 1-Ethoxyethyl-3-methylimidazloium bis(trifluoromethane) sulfonylimide ([EeMim][NTf(2)]) ionic liquid was employed as a demonstration and the prepared fiber was applied to the forensic headspace determination of methamphetamine (MAP) and amphetamine (AP) in human urine samples. Important extraction parameters including the concentration of salt and base in sample matrix, extraction temperature and extraction time were investigated and optimized. Combined with gas chromatography/mass spectrometry (GC/MS) working in selected ion monitoring (SIM) mode, the new method showed good linearity in the range of 20-1500 microg L(-1), good repeatability (RSD<7.5% for MAP, and <11.5% for AP, n=6), and low detection limits (0.1 microg L(-1) for MAP and 0.5 microg L(-1) for AP). Feasibility of the method was evaluated by analyzing human urine samples. Although IL-based SPME is still at the beginning of its development stage, the results obtained by this work showed that it is a promising simple, fast and sensitive sample preparation method.
Journal of chromatography. A 07/2009; 1216(24):4824-30. · 4.19 Impact Factor
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ABSTRACT: Herein is reported the preparation of several series of symmetrical polyammonium salts that serve as cationic lipids or precursors thereof, and are structurally based on several series of parent diamines where dimethylazonia functionalities are present, separated by a central structural unit, and pendant terminal chains. The resultant materials are of significant interest for a variety of purposes, such as serving as antihydrophobic species and as transfectins, the details of which are provided in separate reports. Attempts to effect selective alkylation to provide the corresponding unsymmetrical cationic lipids were without success, always leading to relatively useless mixtures of products.
Chemistry and physics of lipids 06/2009; 160(2):105-8. · 2.15 Impact Factor
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Marie Thomas,
Diego Montenegro,
Alejandra Castaño,
Laura Friedman,
Jay Leb,
Mia Lace Huang,
Leah Rothman,
Heidi Lee,
Craig Capodiferro,
Daniel Ambinder,
Eva Cere,
Jessica Galante,
JaimeLee Rizzo,
Karin Melkonian, Robert Engel
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ABSTRACT: In our continuing investigation of polycationic salts for purposes of antimicrobial action, ion-channel blocking, and construction of ionic liquids, we have prepared several series of polycationic salts derived from carbohydrate precursors. These salts are currently being investigated for optimal efficacy as antibacterials and antifungals, as well as for other applications. The syntheses of such series of salts are described here along with preliminary antibacterial testing results and a discussion of their properties indicating their potential utility for several purposes.
Carbohydrate research 05/2009; 344(13):1620-7. · 2.03 Impact Factor
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Robert Engel,
Jaimelee Iolani Rizzo,
Christina Rivera,
Mariah Ramirez,
Mia Lace Huang,
Diego Montenegro,
Craig Copodiferro,
Valbona Behaj,
Marie Thomas,
Barbara Klaritch-vrana,
Jeanne Fabian Engel
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ABSTRACT: Herein is reported the preparation of several series of polyammonium salts that serve as cationic lipids or precursors thereof, and are structurally based on the parent diamine 1,4-diazabicyclo[2.2.2]octane (dabco). Through selective alkylation of dabco a variety of di- and tetracationic lipid species and precursors thereof have been prepared. The resultant materials are of significant interest for a variety of purposes, including serving as antimicrobial agents and antihydrophobic species, the details of which are provided in separate reports.
Chemistry and physics of lipids 01/2009; 158(1):61-9. · 2.15 Impact Factor
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Synthesis-stuttgart. 01/2009; 2009(09):1437-1444.
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03/2006; , ISBN: 9780470862100
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ABSTRACT: Surfaces bearing carbohydrate units have been modified in a two-step process to incorporate functionalities (lipophilic with polycationic units) that bear antibacterial activity. The effectiveness of these modified surfaces for antibacterial action against a series of seven Gram-positive and Gram-negative bacteria are reported.
Carbohydrate Research 12/2002; 337(24):2495-9. · 2.33 Impact Factor
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Phosphorus Sulfur and Silicon and The Related Elements - PHOSPHOR SULFUR SILICON. 01/2002; 177:2267-2268.
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Heteroatom Chemistry - HETEROATOM CHEM. 01/2000; 11(7):546-555.
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ABSTRACT: Surfaces bearing protein units (wool, silk) have been modified in a two step process to incorporate at the free side-chain hydroxyl groups functionalities (lipophilic with polycationic units) that bear antibacterial activity. The approach has involved tosylation of the hydroxyl groups followed by displacement with a tertiary amine bearing cationic and lipophilic components. The effectiveness of these modified surfaces for antibacterial action against a series of Gram + and Gram - bacteria is reported. Structural factors maximizing the activity against all species tested have been studied and appropriate surfaces have been generated. Preparative procedures along with methods of investigation of the antimicrobial activity are included along with a discussion of mode of activity.
