Lipids

Open-tubular gas chromatographic analysis of fatty acids in the lipids from the seeds of 20 species of Gymnospermae showed that they all contained nonmethylene-interrupted polyenoic (NMIP) acids as minor components and palmitic, oleic, linoleic and α-linolenic acids as major components. The NMIP acids have an additional 5,6-ethylenic bond in ordinary plant unsaturated fatty acids and the following C2 elongation acids:cis-5,cis-9-octadecadienoic acid (5,9–18∶2) (I); 5,9,12–18∶3 (II); 5,9,12,15–18∶4, 5,11–20∶2, 5,11,14–20∶3 (III); and 5,11,14,17–20∶4 (IV). The main NMIP acids found in neutral lipids are I in two species ofTaxus, II in seven species of Pinaceae, III in two species of Podocarpaceae,Torreya nucifera, Cycas revoluta, andGinkgo biloba, and III and IV in each of three species of Taxodiaceae, and Cupressaceae. The polar lipids constitute the minor fraction of seed lipids in general. The content and composition of NMIP acids in these lipids differe considerably from those in neutral lipids. Analysis of the partial cleavage products of triacylglycerols showed that the NMIP acids distribute mainly in the 1,3-position.

Oxidized low-density lipoprotein (OxLDL) plays an important role in initiation and progression of atherosclerosis. Proatherogenic effects of OxLDL have been attributed to bioactive phospholipids generated during LDL oxidation. It is unknown what effect oxidation has on the phosphatidylinositol (PtdIns) molecules in LDL, even though PtdIns is 6% of the total LDL phospholipid pool. We sought to identify and quantitate oxidized phosphatidylinositol (OxPtdIns) species in OxLDL and human atherosclerotic plaque. Bovine liver PtdIns was subjected to non-enzymatic and lipoxygenase-catalyzed oxidation. Reversed-phase liquid chromatography with negative ESI–MS identified and confirmed compounds by fragmentation pattern analysis from which an OxPtdIns library was generated. Twenty-three OxPtdIns molecules were identified in copper-oxidized human LDL at 0, 6, 12, 24, 30, and 48 h, and in human atherosclerotic plaque. In OxLDL, OxPtdIns species containing aldehydes and carboxylates comprised 17.3 ± 0.1 and 0.9 ± 0.2%, respectively, of total OxPtdIns in OxLDL at 48 h. Hydroperoxides and isoprostanes at 24 h (68.5 ± 0.2 and 22.8 ± 0.2%) were significantly greater than 12 h (P < 0.01) without additional changes thereafter. Hydroxides decreased with increased oxidation achieving a minimum at 24 h (5.2 ± 0.3%). Human atherosclerotic plaques contained OxPtdIns species including aldehydes, carboxylates, hydroxides, hydroperoxides and isoprostanes, comprising 18.6 ± 4.7, 1.5 ± 0.7, 16.5 ± 7.4, 33.3 ± 1.1 and 30.2 ± 3.3% of total OxPtdIns compounds. This is the first identification of OxPtdIns molecules in human OxLDL and atherosclerotic plaque. With these novel molecules identified we can now investigate their potential role in atherosclerosis.

Transfer of fatty acids from mother to fetus during pregnancy is a requirement for optimal fetal growth. We report a longitudinal study of full maternal erythrocyte fatty acid profile assessed at each trimester of pregnancy [mean 12.5 (range 8–14), 26.1 (24–28) and 35.5 (33–38) weeks’ gestation] and in the post partum period [18.1 (12–26) weeks]. The study recruited healthy women (n = 47) from routine antenatal clinics at the Princess Royal Maternity Unit, Glasgow, Scotland. There were increases in 16:1n7 (22%, p = 0.0005), 24:1n9 (13%, p = 0.0032), 22:5n6 (25%, p = 0.0003), 18:3n3 (41%, p = 0.0007) and 22:6n3 (20%, p = 0.0005) concentrations during pregnancy. The greatest increases took place between gestations at sampling of 12.5 and 26.1 weeks. The change in 16:1n7 concentration between gestations at sampling of 12.5 and 35.3 weeks was negatively associated with maternal booking body mass index (r = −0.40, p = 0.006). The change in 22:6n3 concentration was correlated with the change in 24:1n9 (r = 0.70, p < 0.001). In samples taken four months post partum, 14:0 concentration was lower (29%, p = 0.0002) and 24:0 concentration (15%, p = 0.0009) and n6/n3 ratio (11%, p = 0.0019) were higher than at a gestation at sampling of 12.5 weeks. In conclusion, several fatty acids are specifically mobilised during pregnancy. The correlation between maternal 22:6n3 and 24:1n9 suggests that mobilisation of these fatty acids may be coordinated. The inverse relationship between 16:1n7 and maternal central obesity warrants further investigation.

The long chain bases of sphingomyelin from Morris hepatoma 7777 and host and control livers were analyzed by capillary gas liquid chromatography. Sphingosine (18∶1) was the major long chain base of control livers (66.5%) and hepatomas (65.6%), but hepatomas also had a high percentage (9.3 vs 4.4) of the 16∶1 homolog. Host liver had the most unusual long chain base composition, with ca. equal 16∶1 (24.4%) and 18∶1 (21.4%) and high amounts of 20-carbon bases (9.2% 20∶0 and 15.3% 20∶1). These differences may be related to the aberrant fatty acid metabolism known to occur in tumor-bearing animals. Such large perturbations in the long chain base composition of hepatic sphingomyelin are unprecedented and could have a major impact on the properties of host membranes.

Studies of the comparative effects of a semi-synthetic diet containing supplements of corn oil, no fat, linolenate ortrans,trans-linoleate on blood coagulation parameters are reported. In spite of large differences in fatty acid composition of the tissue lipids of the different groups, the only diets that appeared to produce abnormal hematologic and hemostatic properties were those containingtrans,trans-linoleate. These groups of animals showed significant differences from a control group of animals fed Purina rat chow in platelet and fibrinogen concentration, and values for hematocrit and prothrombin time. A positive fibrinolysin test was also obtained in about 50% of the animals fedtrans,trans-linoleate.

The effect of a diet containingtrans-fatty acids (tFA) on the fatty acid composition and fat accumulation in adipose tissue was investigated in mice. Male C57BI/6J mice were fed Control or Trans Diets that were similar, except that 50% of the 18∶1, which was allcis in the Control Diet, was replaced bytFA in the Trans Diet. At selected ages, body weight, epididymal fat pad weight, perirenal fat yield, adipose tissue cellularity and fatty acid composition were examined. Over the time period studied (2–24 mon), the proportion of 18∶0 and 16∶0 tended to decrease whilecis-18∶1 levels increased. Compared to the Control Diet, the Trans Diet resulted in adipose tissue lipids with higher percentages of 14∶0 and 18∶2n−6 and lower percentages ofcis-18∶1 and 20∶4n−6. In polar lipids,tFA replaced saturated fatty acids, whereastFA replacedcis-18∶1 in the nonpolar lipids. Body weights at 16 and 24 mon of age and epididymal fat pad weights at 8–24 mon of age were lower in mice fed the Trans Diet as compared to those fed the Control Diet. At the ages studied, the Trans Diet also resulted in lower values for perirenal fat weights, triacylglycerol to polar lipid ratios, and adipose cell size. The data suggest that chronic consumption oftFA affects lipid metabolism and results in decreased fat accumulation in murine adipose tissue.