Proportion Of Eicosapentaenoic Acid Research Articles

Δ6 Desaturase Inhibition

The herbicide Norflurazone was shown to be an inhibitor of fatty acid of the Delta6 desaturation system. Treating cultures of the microalgae Spirulina platensis or Monodus subterraneus with this herbicide brought about a reduction in the level of gamma-linolenic acid and in an increase in the level of linoleic acid. In Monodus, the increase in linoleic acid made it more available for omega3 desaturation, resulting in an increase in the proportion of eicosapentaenoic acid. The proportion of arachidonic acid did not decrease albeit the drastic decrease in its precursor gamma-linolenic acid.

Modulation of hepatic ferrochelatase activity by dietary manipulation of mitochondrial phospholipid fatty acyl groups.

Ferrochelatase is an enzyme bound to the inner mitochondrial membrane, which is important in heme biosynthesis. Activity of purified ferrochelatase is affected by the presence of certain fatty acids. In the present study, we examined whether the activity of ferrochelatase is altered by dietary manipulation of the composition of mitochondrial membrane phospholipid fatty acyl groups. Rats were fed diets containing triolein, safflower or menhaden oil as 5% (w/w) of the diet. After 3 weeks, the animals were killed and liver mitochondria were isolated. Phospholipid fatty acid composition and ferrochelatase activity were assayed in the isolated mitochondria. Marked differences were seen. The proportion of oleic acid was highest in the triolein oil-fed group, that of linoleic and arachidonic acid was highest in the safflower oil-fed group and the proportion of eicosapentaenoic acid was highest in the menhaden oil-fed group. Ferrochelatase activity was greatest in the triolein oil-fed group and lowest in the menhaden oil-fed group regardless of whether the mitochondria were intact, sonicated or sonicated and treated with Tween 20. Mixing of mitochondria from menhaden oil-fed rats with triolein oil resulted in a significant increase in ferrochelatase activity. Membrane fluidity and activities of the mitochondrial membrane enzymes succinic dehydrogenase and cytochrome oxidase did not differ among the groups. We conclude that dietary manipulation of mitochondrial membrane phospholipid fatty acyl group composition can directly modulate hepatic ferrochelatase activity. This has potential application in the treatment of protoporphyria, the genetic disorder in which ferrochelatase activity is deficient.

Influence of highly concentrated n-3 fatty acids on serum lipids and hemostatic variables in survivors of myocardial infarction receiving either oral anticoagulants or matching placebo

Forty patients with previous myocardial infarction were given 4 capsules with 1 g concentrated fish oil preparation daily for 4 weeks. No special diet was applied. The supplementation was equivalent to 3.4 grams of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) daily. Twenty-two of the 40 subjects received concomitant treatment with long-term oral anticoagulants (OAC). The fatty acid composition of serum after the supplementation period showed a significant increase in the proportion of EPA and DHA, while arachidonic acid (AA) remained essentially constant. This resulted in a rise of the EPA/AA ratio from 0.59 to 1.49 (p<0.001), confirming satisfying absorption of the concentrate. Blood lipids showed an overall decrease of triglycerides (TG) by 25% (p=0.02), while total cholesterol rose by 5% (p=0.03) and HDL-cholesterol was unaffected. Blood glucose and the TG associated factors plasminogen activator inhibitor and factor VII-phospholipid complex revealed trends towards reduction. Ivy bleeding time showed a significant prolongation, the median increasing from 240 to 270 seconds. A significant increase of fibrinogen was seen, as was a decrease of clotting time in the combined prothrombin test in patients receiving concomitant OAC. Thus, given for 4 weeks, the investigated concentrate of n-3 fatty acids exerts not merely beneficial effects as far as the risk profile for atherosclerotic disease is concerned. The results also point towards interactions with OAC that may be of clinical relevance.

Dietary Effects of Menhaden Oil on the Growth and Membrane Lipid Composition of Rat Mammary Tumors234

The objective of this study was to evaluate the effect of quantitative differences in dietary menhaden oil, an n-3 polyunsaturated marine oil, on mammary tumor development and to compare these results with those produced by corn oil, an n-6 polyunsaturated vegetable oil. Inbred female BUF rats were treated with the carcinogen N-methyl-N-nitrosourea (CAS: 684-93-5) and maintained on diets containing graded levels of each of the respective oils. Our results indicated that diets containing 20% menhaden oil produced a reduction in tumor incidence and a prolongation of the tumor latent period. This finding contrasted sharply with the enhanced tumor development and shortened latent period observed in the animals fed the equivalent dietary level of corn oil. Fatty acid analyses performed on the lipids extracted from the tumor and hepatic microsomes of the animals on the menhaden oil diets demonstrated that the proportion of eicosapentaenoic acid (No. of C-atoms:No. of double bonds = 20:5) present in these microsomal lipids was related inversely to mammary tumor development.

Effects of dietary fish oil supplementation on the fatty acid composition of the human platelet membrane: demonstration of selectivity in the incorporation of eicosapentaenoic acid into membrane phospholipid pools.

The fatty acid composition of membrane phospholipids of stimulated and unstimulated platelets was studied in six normal volunteers given a daily dietary supplement of a fish oil rich in eicosapentaenoic acid (EPA) for 4 weeks. The supplement was equivalent to 1.8 g of EPA daily. Thromboxane synthesis and platelet aggregation responses to sodium arachidonate, thrombin and the ionophore A23187 were also investigated. A marked increase in the relative EPA content of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was noted after 2 and 4 weeks fish oil supplementation. However, there was no incorporation into phosphatidylinositol (PI) or phosphatidylserine (PS). The relative arachidonic acid (AA) content of PC and PE was significantly reduced at 2 and 4 weeks but that of PI and PS remained unchanged. Significant reductions in the relative linoleic acid content of total phospholipids, PC and PE were also noted. Stimulation of platelets obtained after 4 weeks fish oil supplementation by thrombin and A23187 was associated with a marked reduction in the AA content of PI and a minor reduction in that of PE. There was no change in the relative proportions of EPA in PI, PS, PC or PE after stimulation. Throughout the study there were no significant changes in platelet aggregation responses or in platelet thromboxane production. Our results indicate that the incorporation of EPA into the platelet membrane phospholipids is selective and that if PI is the major source of AA for platelet prostaglandin biosynthesis then the reported beneficial effects of EPA on haemostasis cannot be explained on the basis of its incorporation into and mobilization from the platelet membrane phospholipid pool.