Bile acid composition of rainbow trout,Salmo gairdneri

The bile acid composition and metabolism of rainbow troutSalmo gairdneri has been investigated by thin layer chromatography, gas liquid chromatography, and radio gas liquid chromatography methods. For this purpose gallbladder bile was collected from fed fish at 6 and 13 months and from starved fish at 12 months of age. Cholic acid was found to be the main component and constituted over 85% of total. Chenodeoxycholic acid accounted for 14% or less and the 3α, 12α-7-keto- and 7α, 12α-3-keto-5β-cholanoates for 1% or less of total. The bile acids were conjugated mainly with taurine, only small amounts of glycocholic acid being detected. Ca. 5% of the taurocholate was sulfated, as were trace amounts of cholic and glycocholic acids. The size of the bile acid pool was found to increase in the older fish and to decrease in starved fish. Unlike mammalian livers, the livers of the trout converted radioactive chenodeoxycholic acid into cholic acid.     

Studies of triacyglycerol structure of very low density lipoproteins of normolipemic subjects and patients with type III and type IV hyperlipoproteinemia

The triacylglycerols of very low density lipoproteins (VLDL-TG) were analyzed in samples from normal subjects and patients with Frederickson’s Type III and Type IV hyperlipoproteinemia. VLDL were obtained by conventional ultracentrifugation, and the triacylglycerols were isolated by thin-layer chromatography (TLC). Representative sn-1,2(2,3)- and sn-1,3-diacylglycerols were generated by Grignard degradation of the triacylglycerols, and were resolved by TLC on borate-treated silica gel. The molecular association of the fatty acids in the diacylglycerol moieties was determined by gasliquid chromatography with mass spectrometry (GC/MS) of the tertiary-butyldimethylsilyl ethers. The positional distribution of the fatty acids was established by the Brockerhoff stereospecific analysis. The results showed a marked asymmetry in the distribution of the fatty acids in all samples, with the saturated acids predominantly in the sn-1-position and the unsaturated fatty acids distributed about equally between the sn-2- and sn-3-positions. In all instances, the molecular species composition of the sn-1,2-, sn-2,3- and sn-1,3-diacylglycerols was found to be similar to that calculated for 1-random 2-random 3-random distribution of triacylglycerols. There were marked differences in the quantitative composition of the molecular species of the VLDL-TG between normal subjects and patients, but these discrepancies were attributed to differences in the fatty acid composition of the samples.     

Hydrolysis of polyhydroxy polyunsaturated fatty acid-glycerophosphocholines by Group IIA,V, and X secretory phospholipases A2

It is widely accepted that unesterified polyunsaturated ω-6 and ω-3 fatty acids (PUFA) are converted through various lipoxygenases, cyclooxygenases, and cytochrome P450 enzymes to a range of oxygenated derivatives (oxylipins), among which the polyhydroxides of unesterified PUFA have recently been recognized as cell signaling molecules with anti-inflammatory and pro-resolving properties, known as specialized pro-resolving mediators (SPMs). This study investigates the mono-, di-, and trihydroxy 16:0/PUFA-GPCs, and the corresponding 16:0/SPM-GPC, in plasma lipoproteins. We describe the isolation and identification of mono-, di-, and trihydroxy AA, EPA, and DHA-GPC in plasma LDL, HDL, HDL3, and acute phase HDL using normal phase LC/ESI-MS, as previously reported. The lipoproteins contained variable amounts of the polyhydroxy-PUFA-GPC (0–10 nmol/mg protein), likely the product of lipid peroxidation and the action of various lipoxygenases and cytochrome P450 enzymes on both free fatty acids and the parent GPCs. Polyhydroxy-PUFA-GPC was hydrolyzed to variable extent (20%–80%) by the different secretory phospholipases A₂ (sPLA₂s), with Group IIA sPLA₂ showing the lowest and Group X sPLA₂ the highest activity. Surprisingly, the trihydroxy-16:0/PUFA-GPC of APHDL was largely absent, while large amounts of unidentified material had migrated in the free fatty acid elution area. The free fatty acid mass spectra were consistent with that anticipated for branched chain polyhydroxy fatty acids. There was general agreement between the masses determined by LC/ESI-MS for the polyhydroxy PUFA-GPC and the masses calculated for the GPC equivalents of resolvins, protectins, and maresins using the fatty acid structures reported in the literature.