Occurrence of New Polyenoic Very Long Chain Acyl Residues in Lipids from Acanthamoeba castellanii

The cellular fatty acid composition of Acanthamoeba castellanii, a unicellular bacteriovorous organism, was reinvestigated. Lipids from amoebae grown axenically in proteose peptone-yeast extract-glucose medium were extracted with chloroform-methanol and separated by silicic acid column chromatography into non-polar and polar fractions. The fatty acid composition of the lipids and the double-bond position of the unsaturated acids have been determined by capillary gas chromatography-mass spectrometry (GC-MS) of their corresponding methyl esters, 2-alkenyl-4,4-dimethyloxazoline (DMOX) derivatives and dimethyldisulfide (DMDS) adducts. Evidence is given that lipids from A. castellanii in addition to the three already identified saturated straight chain fatty acids: tetradecanoic (C14:0), hexadecanoic (C16:0), octadecanoic (C18:0), and six preponderant unsaturated fatty acids: hexadecenoic (C16:1 Δ^7), octadecenoic (C18:1 Δ^9), octadecadienoic (C18:2 Δ(superscript 9, 12)), eicosadienoic (C20:2 Δ(superscript 11, 14)), eicosatrienoic (C20:3 Δ(superscript 8, 11, 14)), and eicosatetraenoic (C20:4 Δ(superscript 5, 8, 11, 14)), contain additionally four very long chain unsaturated fatty acids: octacosenoic (C28:1 Δ^21), octacosadienoic (C28:2 Δ(superscript 5, 21)), triacontadienoic (30:2 Δ(superscript 21, 24)), and triacontatrienoic (C30:3 Δ(superscript 5, 21, 24)) previously unreported in lipids of A. castellanii. These new long chain fatty acids account for approximately 25% of total fatty acids. To our knowledge, this is the first report of very long chain polyenoic fatty acids present in lipids extracted from A. castellanii cells.

並列關鍵字

Acanthamoeba castellanii ； endoparasites ； long chain polyenoic fatty acids ； double bond position ； dimethyloxazoline derivatives ； dimetyldisulfide adducts ； non- methylene interrupted fatty acids

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