Search results for "lipids"

Synthesis of (E)- and (Z)-29-methylidyne-2,3-oxidosqualene derivatives as inhibitors of liver and yeast oxidosqualene cyclase

2002

The synthesis of (E)- and (Z)-29-methylidyne-2,3-oxidosqualene derivatives is described starting from the C22 and C17 squalene aldehyde monobromohydrins. The conversion was achieved by means of a Wittig reaction, followed by desilylation of the terminal acetylene. For trisubstituted 1,3-enynes, preliminary alkylation with a suitable allyl bromide was performed. A new procedure for the synthesis of squalene aldehyde C27, C22 and C17 monobromohydrins is also described. Some of the new compounds behaved as inhibitors of pig liver and yeast oxidosqualene cyclase and were time-dependent inhibitors of the animal enzyme.

Insights into catanionic vesicles thermal transition by NMR spectroscopy

2012

Oppositely charged ionic surfactants can self-assemble into hollow structures, called catanionic vesicles, where the anionic-cationic surfactant pair assumes a double-tailed zwitterionic attitude. In the present work, multilamellar- to-unilamellar thermal transition of a mixed aqueous system of sodium dodecyl sulphate (SDS) and cetyl trimethyl ammonium bromide (CTAB), with a slight excess of the anionic one, has been investigated by 1H, 2H, 14N NMR spectra and 23Na transverse relaxation measurements. It has been inferred that an increase of the temperature enhances the SDS counterion dissociation, which can be considered as one of the driving forces of the mentioned transition. Moreover, in…

Heat capacities, volumes and solubilities of pentanol in aqueous alkyltrimethylammonium bromides

1988

Apparent molar heat capacities and volumes of pentanol, 0.05m in decyl-, tetradecyl- and hexadecyltrimethylammonium bromides micellar solutions, were measured at 25°C. They were assumed to approach the standard infinite dilution values and rationalized by means of previously reported equations following which the distribution constant between the aqueous and the micellar phase, heat capacity, and volume of pentanol in both phases are simultaneously derived. The present results show that the volume of the micellar core does not seem to have a significant effect on the apparent molar volume and heat capacity of pentanol in the micellar phase and on the free energy of transfer of pentanol from…

Characterization of Biodiesel from Vegetable Oil Using Comprehensive Two-Dimensional Gas Chromatography

2012

Biodiesel from vegetable oils has been analyzed and its suitability for internal combustion engines has been assessed. The Standard biofuel’s characteristics have been investigated. Gas chromatography (GC) tests were carried out to characterize the fatty acid behavior. It was found that the mass percentage of saturated fatty acids did not change substantially with time, while unsaturated fatty acids increased with time for both B100 and B30. An increase in density for B100 and B30 with time was noted. Biodiesel density was within the standardization. The calorific values of biodiesel and its blend increased with time. Higher heating value for B100 increased from 41 to 43 MJ/kg while B30 inc…

Influence of functionalization on interaction and drug release from α,β-polyaspartylhydrazide derivatives to a biomembrane model: evaluation by diffe…

2004

Abstract A comparative study on the ability of various polymers to interact with a biomembrane model was carried out by differential scanning calorimetry (DSC). The investigated samples were a water soluble polymer, the α,β-polyaspartylhydrazide (PAHy) and its derivatives containing polyethylene glycol (PEG2000) (sample PAHy–PEG2000), or hexadecylamine (C16) (sample PAHy–C16) or both compounds (sample PAHy–PEG2000–C16). Some samples are able to arrange themselves as micellar structures and to interact potentially with the membrane surface so as to favor the release of the drug near the target membrane and consequently to improve drug adsorption processes. First, the interaction of all polym…

Analysis of adsorption of phospholipids at the 1,2-dichloroethane/water interface by electrochemical impedance spectroscopy: A study of the effect of…

2007

Abstract The adsorption behaviour of a series of phosphatidylcholines (PCs) with saturated carbon chains of different length (DLPC, DPPC, DSPC, DAPC, and DBPC) at the electrified 1,2-dichloroethane/water interface was studied by measuring electrochemical impedance spectroscopy at the polarized interface. Two different trends in the interfacial capacitance were observed for any of the PCs the capacity dependence on the applied potential: strong adsorption occurs at negative potential with a marked decrease of C ( E ); increase of capacity is observed at positive potentials. It is demonstrated that the interfacial lipid adsorption was dependent on phospholipid concentration, applied potential…

ChemInform Abstract: Alkylation of Lithium Dienediolates of Butenoic Acids. Regioselectivity Effects of Structure and Leaving Group of the Alkylating…

2010

Abstract Regioselectivity of alkylation of but-2-enoic acids 1 and 2 by alkyl halides strongly depends on the reactivity of the electrophile. High α selectivity results for saturated alkyl halides, whereas poor α-selectivity is obtained for highly reactive allyl and benzyl halides. For reactive alkylating halides selectivity is partly governed by the ion pairing aggregates of the dienediolates. Lithium bromide and the carboxylate generated in the ongoing reaction cause opposite effects on regioselectivity.

1983

Introduction des groupes alkyl dans le polyamide commercial Trogamid T. Formation d'anions polyamides par l'hydrure de sodium puis alkylation par les bromures d'alkyle

A minimal hydrophobicity is needed to employ amphiphilic p(HPMA)-co-p(LMA) random copolymers in membrane research.

2014

Because a polymer environment might be milder than a detergent micelle, amphiphilic polymers have attracted attention as alternatives to detergents in membrane biochemistry. The polymer poly[N-(2-hydroxypropyl)-methacrylamid] [p(HPMA)] has recently been modified with hydrophobic lauryl methacrylate (LMA) moieties, resulting in the synthesis of amphiphilic p(HPMA)-co-p(LMA) polymers. p(HPMA)-co-p(LMA) polymers with a LMA content of 5 or 15% have unstable hydrophobic cores. This, on one hand, promotes interactions of the hydrophobic LMA moieties with membranes, resulting in membrane rupture, but at the same time prevents formation of a hydrophobic, membrane mimetic environment that is suffici…

The relationship between feed intake behaviour with intramuscular fat, cholesterol and fatty acid composition in pork

2011

The aim of this study was to investigate the phenotypic relationship between feed intake (FI) characteristics with intramuscular fat, cholesterol and fatty acid composition in pork. Data were available on 202 Duroc barrows. Intramuscular fatness was positively correlated with a higher percentage of saturated (SFA) and monounsaturated fatty acids (MUFA), a lower percentage of polyunsaturated (PUFA), omega-3 (ω3) and omega-6 (ω6) fatty acids, and a lower ω6/ω3 and P:S ratio (p < 0.05). Faster growth resulted in a higher level of SFA and a lower level of ω3 fatty acids (p < 0.05). Increased FI, residual feed intake (RFI) and feed intake time (TIME) and a decreased feed intake frequency (FREQ) …