stearates and methyl-oleate

We recently reported the characterization of novel cholesterol esterase (EC. 3.1.1.13) from Trichoderma sp. and preliminary work on sterol ester synthesis. In the present study, we further examined the enzyme ability to synthesize cholesterol esters from cholesterol and free fatty acids of various chain lengths, and compared the fatty acid specificity in synthesis with that in hydrolysis. The enzyme catalyzed the synthesis of medium- and long-chain fatty acid cholesterol esters, but failed to synthesize short-chain fatty acid esters. The fatty acid specificities in the synthesis and hydrolysis of cholesterol esters were entirely different from each other. Unlike other lipolytic enzymes, the enzyme was largely independent of water content in the synthesis of cholesterol oleate, and it achieved near-complete esterification in the presence of an equimolar excess of oleic acid. Of additional interest is the finding that the addition of n-hexane markedly enhanced the esterification activities on all the medium- and long-chain saturated fatty acids used. Based on these findings, we attempted to synthesize stigmasterol stearate as a food additive to lower cholesterol levels in blood plasma, and found that the enzyme catalyzed effective synthesis of the ester without the need of dehydration during the reaction, indicating the potential utility of the enzyme in the food industry.

Topics: Anticholesteremic Agents; Biocatalysis; Cholesterol; Cholesterol Esters; Esterification; Fatty Acids; Fatty Acids, Volatile; Food Additives; Food Industry; Fungal Proteins; Hexanes; Hydrolysis; Molecular Structure; Oleic Acid; Oleic Acids; Phytosterols; Stearates; Sterol Esterase; Stigmasterol; Substrate Specificity; Trichoderma; Triolein; Water

The solvent type strongly affects the nucleation behavior of 12HSA and therefore strongly influences the peak nucleation rate, fiber length, spatial distribution of mass, and degree of branching. Using nonisothermal kinetic models, a correlation was established among the activation energy of nucleation, fiber length, and induction time of 12HSA nucleation in different solvents. However, there was no correlation between any measurable parameter and solvent polarity. Activation energies varied from 2.2 kJ/mol in methyl oleate to 15.8 kJ/mol in glycerol. Nucleation behavior and structure were strong functions of the cooling rate, with distinct regions observed above and below 5-7 degrees C/min for fiber length, induction time, rate constant, and peak nucleation rate. The abrupt changes in the rate of nucleation, crystal growth rate constant, and degree of branching around this cooling rate are related to whether the nucleation and crystal growth processes are governed by mass transfer or thermodynamics. Furthermore, the Avrami equation accurately predicted several structural features of the fibrillar network such as fiber length and, to a lesser extent, induction time.

Topics: Algorithms; Calorimetry, Differential Scanning; Chemistry; Crystallization; Glycerol; Kinetics; Light; Models, Statistical; Oleic Acids; Probability; Solvents; Stearates; Succinates; Surface Properties; Temperature; Thermodynamics; Time Factors

A facile (and environmentally friendly) reaction between epoxidized methyl oleate and aniline to produce an oleate-aniline adduct, without the formation of fatty amide, was discovered. This reaction was carried out neat, with a catalytic amount of an ionic liquid. No solvent was used, no byproducts were produced, and the ionic liquid could be recovered and recycled. The reaction products were fully characterized by NMR and GC-MS.

Topics: Aniline Compounds; Borates; Catalysis; Formates; Gas Chromatography-Mass Spectrometry; Hydrogen Peroxide; Imidazoles; Indicators and Reagents; Magnetic Resonance Spectroscopy; Oleic Acids; Solutions; Stearates

The Friedel-Crafts adducts of methyl oleate with benzene and toluene have been synthesized. The products are a mixture of monomer, dimer and trimer esters together with adducts containing one, two or three molecules of ester per mol of aromatic compound, depending on the proportions of starting material used. The 1H- and 13C-NMR spectra of the adducts are reported together with their mass spectra.

Topics: Benzene; Chemical Phenomena; Chemistry; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Oleic Acids; Stearates; Toluene

Methyl oleate (18:1) and linoleate (18:2) were readily transformed to the corresponding gem-dichlorocyclopropane derivatives in high yield, using triethylbenzylammonium chloride as the phase-transfer catalyst in the presence of aqueous NaOH and CHCl3. Reaction of dichlorocarbene with methyl 12-hydroxystearate furnished methyl 12-chlorostearate (49%) and 12-O-formylstearate (19%). The hydroxy group in methyl ricinoleate was protected (O-tetrahydropyran-2'-yl) prior to dichlorocyclopropanation of the ethylenic bond. Removal of the protecting group allowed the hydroxy group to be converted to a chloride, O-acetyl, azido or O-formyl function. Treatment of methyl ricinoleate with thionyl chloride, followed by the reaction with dichlorocarbene gave the corresponding 12-chloro-dichlorocyclopropane derivative. The dichlorocyclopropane derivative of oleic acid was transformed to a C19 allenic fatty acid when treated with t-butyl lithium. However, the remaining dichlorocyclopropane derivatives containing an additional functional group in the alkyl chain, failed to yield the corresponding allenic derivatives. All derivatives were characterized by a combination of spectroscopic and chromatographic techniques, including infrared, 1H nuclear magnetic resonance (NMR), and 13C NMR spectroscopy.

Topics: Catalysis; Cyclopropanes; Fatty Acids; Linoleic Acids; Oleic Acids; Ricinoleic Acids; Stearates

Epoxymethylsterate, 9,10- and 12,13-epoxymethyloleates, and a mixture of isomers of epoxymethylarachidonate and diepoxymethylstearate were synthesized, and their metabolic rates were measured using crude and purified cytosolic epoxide hydrolase. Hepatic epoxide hydrolase was purified from human samples and clofibrate-fed mice by affinity chromatography. The major metabolites under these conditions of all the epoxy fatty esters were their vicinal diols whose structures were confirmed by GC-MS. 12,13-Epoxymethyloleate was metabolized faster than 9,10-epoxymethyloleate and other epoxy fatty esters, but all substrates were turned over rapidly. This rapid turnover suggests that epoxy fatty acids may be endogenous substrates for the cytosolic epoxide hydrolase.

Topics: Animals; Arachidonic Acids; Chromatography, Gas; Epoxide Hydrolases; Epoxy Compounds; Ethers, Cyclic; Fatty Acids; Female; Gas Chromatography-Mass Spectrometry; Humans; Kinetics; Liver; Male; Mice; Oleic Acids; Stearates