title: Absorption and metabolism of cis-9,trans-11-CLA and of its oxidation product 9,11-furan fatty acid by Caco-2 cells.
abstract: Furan fatty acids (furan-FA) can be formed by auto-oxidation of conjugated linoleic acids (CLA) and may therefore be ingested when CLA-containing foodstuff is consumed. Due to the presence of a furan ring structure, furan-FA may have toxic properties, however, these substances are toxicologically not well characterized so far. Here we show that 9,11-furan-FA, the oxidation product of the major CLA isomer cis-9,trans-11-CLA (c9,t11-CLA), is not toxic to human intestinal Caco-2 cells up to a level of 100 μM. Oil-Red-O staining indicated that 9,11-furan-FA as well as c9,t11-CLA and linoleic acid are taken up by the cells and stored in the form of triglycerides in lipid droplets. Chemical analysis of total cellular lipids revealed that 9,11-furan-FA is partially elongated probably by the enzymatic activity of cellular fatty acid elongases whereas c9,t11-CLA is partially converted to other isomers such as c9,c11-CLA or t9,t11-CLA. In the case of 9,11-furan-FA, there is no indication for any modification or activation of the furan ring system. From these results, we conclude that 9,11-furan-FA has no properties of toxicological relevance at least for Caco-2 cells which serve as a model for enterocytes of the human small intestine.
authors.affiliation: Department of Food Safety, Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany. thorsten.buhrke@bfr.bund.de
authors.forename: Thorsten
authors.initials: T
authors.lastname: Buhrke
authors.forename: Roswitha
authors.initials: R
authors.lastname: Merkel
authors.forename: Imme
authors.initials: I
authors.lastname: Lengler
authors.forename: Alfonso
authors.initials: A
authors.lastname: Lampen
mesh_terms: D000042:Absorption; D000123:Acetyltransferases / Q000378:metabolism; D001391:Azo Compounds; D001711:Biotransformation; D018938:Caco-2 Cells; D002470:Cell Survival / Q000187:drug effects; D020895:Enterocytes / Q000378:metabolism; D000081031:Fatty Acid Elongases; D005663:Furans / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007536:Isomerism; D044243:Linoleic Acids, Conjugated / Q000378:metabolism* / Q000494:pharmacology; D050356:Lipid Metabolism; D008954:Models, Biological; D010084:Oxidation-Reduction; D014280:Triglycerides / Q000096:biosynthesis*
chemical_list: D001391:Azo Compounds; D005663:Furans; D044243:Linoleic Acids, Conjugated; D014280:Triglycerides; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases; C011049:oil red O