ABSTRACT
Esterification of glycerol with conjugated linoleic acid (CLA) was carried out in hexane. Lipase from Rhizomucor miehei provided a high degree of esterification (80%) in 8 h at 50 degrees C when used at 15% (w/w) in a system containing a 1:2 molar ratio of glycerol to free fatty acids. Esterification levels >80% were obtained in 8 h at 40 degrees C with 15% (w/w) lipase from Candida antarctica at the same molar ratio of reactants. The extent of esterification of CLA was >90% after 4 h of reaction at 50 degrees C with a 5% (w/w) loading of either R. miehei or C. antarctica lipase, together with a 1:1 molar ratio of substrates. Both enzymes incorporated the original CLA as acylglycerol residues in primarily 1,3-diacylglycerol and 1-monoacylglycerol. The CLA-rich acylglycerols can be employed as emulsifiers or as substitutes for natural fats and oils.
Subject(s)
Diglycerides/biosynthesis , Glycerides/biosynthesis , Glycerol/metabolism , Linoleic Acids, Conjugated/metabolism , Lipase/metabolism , Chromatography, High Pressure Liquid , Enzymes, Immobilized , Food Technology/methods , Glycerides/chemistry , Hexanes , Rhizomucor/enzymology , TemperatureABSTRACT
Two Candida antarctica lipases catalyze the enantioselective acylation of N-substituted trans-4-(4'-fluorophenyl)-3-hydroxymethylpiperidines in organic solvents. These two lipases show opposite stereochemical preference in these processes. Both enantiomers can be obtained in their optically pure forms. The (3S,4R) isomer, is an intermediate for the synthesis of (-)-Paroxetine.
Subject(s)
Benzene Derivatives/chemistry , Piperidines/chemistry , Acetylation , Candida/enzymology , Hydrolysis , Indicators and Reagents , Lipase/chemistry , Magnetic Resonance Spectroscopy , Paroxetine/chemistry , Solvents , StereoisomerismABSTRACT
1. The binding of 60 drugs, mainly steroids, to opioid receptors was studied in crude membrane fractions from mouse brains. 2. Competition assays with the different drugs (5 x 10(-7)-10(-4)M) were performed by labeling opiate receptors with [3H]diprenorphine (0.3-0.4 nM). 3. Only 7 drugs (alpha,5beta-tetrahydrodeoxycorticosterone, megestrol acetate, mifepristone, 17alpha-ethynylestradiol, diethylstilbestrol, clomiphene citrate and tamoxifen citrate) inhibited [3H]diprenorphine binding more than 50% at the highest concentration assayed (10(-4) M). The IC50 values ranged between 6x10(-5) M. 4. Thus, the present results show that only a limited number of steroids, from diverse classes, bind to opiate receptors.
