A one-vial method for routine extraction and quantification of free fatty acids in blood and tissue by HPLC.
ABSTRACT A one-vial procedure has been developed to quantify free fatty acids in human blood serum and rat heart tissue. To allow routine analysis the system has been constructed to allow simultaneous processing of nine samples (Praechromat). The free fatty acids are extracted with Freon 11 and then derivatized to coumarin esters prior to HPLC. The Freon 11 extraction of the free fatty acids is rapid and complete. Neither hydrolytic degradation of natural fatty acid esters nor oxidative damage of unsaturated fatty acids was observed. Fifteen free fatty acids (FFA) were routinely quantified by isocratic elution with high reproducibility (SD less than 4%) and good recovery (0.1 mM FFA: 98-100%, 0.02 mM: 91-105%). The free fatty acids could be determined in the range from 20 pmol to 20 nmol.
Article: Natural ligands of PPARγ[Show abstract] [Hide abstract]
ABSTRACT: The peroxisome proliferator-activated receptor (PPAR) family was discovered from an orphan nuclear receptor approach, and thereafter, three subtypes were identified, namely PPARα, PPARβ or PPARδ and PPARγ. The two former seem to regulate lipid homeostasis, whereas the latter is involved, among others, in glucose homeostasis and adipocyte differentiation. PPARs were pharmacologically characterised first using peroxisome proliferators such as clofibrates, which demonstrate moderate affinity (efficiency at micromolar concentrations) and low PPARα/δ versus PPARγ specificity. Hence, several laboratories have started the search for potent and subtype-specific natural PPAR activators. In this respect, prostaglandin (PG)-related compounds were identified as good PPARγ agonists with varying specificity, the most notable PPARγ ligand being 15-deoxy-Δ12–14-PGJ2 (15d-PGJ2). Recently, an oxidized phosphatidylcholine was identified as a potent alternative (patho)physiological natural ligand of PPARγ. In the present review, we discuss the different PPARγ-dependent and -independent biological effects of the PG PPARγ ligands and the concern about their low potency in molecular models as compared with thiazolidinediones (TZDs), a family of potent (nanomolar) synthetic PPARγ ligands. Finally, the oxidized lipids are presented as a novel and interesting alternative for discovering potent PPARγ activators in order to understand more in details the implications of PPARγ in various pathophysiological conditions.Cellular Signalling 07/2002; 14(7):573-583. DOI:10.1016/S0898-6568(01)00281-9 · 4.47 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: We examined effects of exogenous very-long-chain fatty acids on lipids of cultured chick neurons and astrocytes. When chick neurons were incubated in chemically defined medium containing 10 μMnervonic acid (C24:1) for 7 days, it was found that a major fatty acid moiety of gangliosides and sphingomyelin was nervonic acid itself, which was not normally detected in the sphingolipid fraction. This alteration in the fatty acid composition apparently occurred in each ganglioside species. Under these experimental conditions, nervonic acid was not found in the glycerophospholipid fraction, and the amounts of triacylglycerol and free nervonic acid increased. Addition of behenic acid (C22:0) or erucic acid (C22:l) also induced changes in the fatty acid composition of gangliosides. When chick astrocytes were incubated in the presence of 10 μM nervonic acid for 7 days, no significant change was observed in the fatty acid composition of gangliosides. These studies indicate that the manipulation of the fatty acid moiety of sphingolipids in cultured neurons is possible.Journal of Neurochemistry 08/1991; 57(2). DOI:10.1111/j.1471-4159.1991.tb03774.x · 4.24 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Summary A simple and sensitive method is described for the determination of biologically important fatty acids including dodecanoic, tetradecanoic, hexadecanoic, octadecanoic, hexadecenoic, octadecenoic and octadecadienoic acids. The method is based derivatization with (2-(2-naphthoxy)ethyl 2-(piperidino)ethanesulfonate (NOEPES) in toluene using potassium carbonate and 18-crown-6 as reaction activators. The resulting naphthoxyethyl derivatives were simply analyzed by isocratic HPLC with fluorometric detection (λex=235 nm, λem=350 nm). The excess fluorescence reagent (NOEPES) was readily removed after derivatization by a quick acid treatment. This minimizes the interference of excess NOEPES in fluorometric detection. The lower limit of quantitation 50 nM with a detection limit (S/N=3) of about 7.5 nM (or 0.15 pmol per 20 μL injection). Application of the method to analysis of free fatty acids in plasma proved feasible (using only 10 μL of plasma sample).Chromatographia 01/2001; 53. DOI:10.1007/BF02490337 · 1.37 Impact Factor