Sigmundur Gudbjarnason

The preparation of triglycerides highly enriched with ω-3 polyunsaturated fatty acids via lipase catalyzed interesterification

Abstract The preparation of triglycerides highly enriched with n-3 polyunsaturated fatty acids, EPA and DHA in particular, via interesterification of cod liver oil and free fatty acid or ethyl ester concentrates catalyzed by an immobilized 1,3-specific lipase from Mucor miehei, is described.

Modification of fatty acid composition of rat heart lipids by feeding cod liver oil

Modification of the fatty acid composition of cardiac phospholipids and neutral lipids was studied in rats fed a diet containing 10% cod liver oil. The results reflect the dynamic state of esterified fatty acids in neutral lipids and phospholipids of heart muscle. In cardiac neutral lipids there was a moderate but significant increase in exogenous fatty acids, 20:1(n--9), 22:1(n--11), 20:5(n--3) and 22:6(n--3), in animals fed cod liver oil, and a relative decrease in endogenous fatty acids, 16:0, 18:2(n--6 and 20:4(n--6). Increased dietary availability of 22: 6(n--3) resulted in a major increase in the content of this fatty acid in phospholipids and replacement of 18:2(n--6) and 20:4(n--6). The 22:6(n--3) was able to replace one third of 18:2(n--6): further increase in 22: 6n--3) was accompanied by a decrease in 18:0. An inverse relationship between (n--6) and (n--3) polyene fatty acids in cardiac phospholipids suggests a replacement of (n--6) acids by (n--3) fatty acids.

Reversible alterations in fatty acid profile of glycerophospholipids in rat heart muscle induced by repeated norepinephrine administration

Rats were injected subcutaneously for 2 weeks with increasing amounts of norepinephrine. The lipid composition of the heart muscle was examined for nearly 2 months. The treatment caused major changes in fatty acyl chain composition of myocardial phosphatidylethanolamine and phosphatidylcholine. In these phospholipids, linoleic acid was decreased to about half of the control value but docosahexaenoic acid increased about 50% in phoshatidylethanolamine and more than doubled in phosphatidylcholine. Arachidonic acid content rose about 50% in phosphatidylcholine but was lowered in phosphatidylethanolamine. The cardiolipin fraction retained its high amount of linoleic acid and the fatty acid composition of the triacylglycerol was not altered, although the amount was significantly decreased. These changes reverted to control levels in 4-8 days after the final injection, although rebound behaviour was observed. An inverse relationship between arachidonic acid content of phosphatidylcholine and phosphatidylethanolamine was observed.

Reduced arachidonic acid levels in major phospholipids of heart muscle in the diabetic rat.

The fatty acid composition of phospholipids and triglycerides in heart muscle was examined in normal and alloxan-diabetic male Wistar rats. In diabetes the major phospholipids, phosphatidyl choline and phosphatidyl ethanolamine, showed significant changes in fatty acid composition, whereas cardiolipin and phosphatidyl serine + phosphatidyl inositol did not show marked changes in fatty acid profile. In phosphatidyl choline there was a significant diminution in arachidonic acid, 20 : 4(n-6) and palmitic acid, 16 : 0, and a corresponding increase in linoleic acid, 18 : 2(n-6), and stearic acid, 18 : 0. In phosphatidyl ethanolamine the level of 20 : 4(n-6) was significantly reduced. The diabetic heart had normal levels of individual phospholipids, whereas the triglycerides were increased by 90% and contained significantly higher levels of 18 : 2(n-6). The results confirm that diabetes is associated with a diminution in fatty acid desaturation, affecting the fatty acid composition of phosphatidyl choline in particular. These changes may be relevant to development of atherosclerosis and relative resistance to catecholamine-induced cardiac necrosis in diabetes.

Inhibition of Acetylcholinesterase by Extracts and Constituents from Angelica archangelica and Geranium sylvaticum

The aim of this study was to explore the acetylcholinesterase (AChE) inhibition of several Icelandic medicinal herbs. Ethanolic extracts of Angelica archangelica seeds and the aerial parts of Geranium sylvaticum proved effective, with IC50 values of 2.20 mg/ml and 3.56 mg/ml, respectively. The activity of imperatorin and xanthotoxin from A. archangelica was measured. Xanthotoxin proved much more potent than imperatorin, with an IC50 value of 155 μg/ml (0.72 mM) but that for imperatorin was above 274 μg/ml (1.01 mM). However, furanocoumarins seem to have a minor part in the total activity of this extract. Synergistic interaction was observed between the extracts of A. archangelica and G. sylvaticum. Several medicinal herbs (Achillea millefolium, Filipendula ulmaria, Thymus praecox and Matricaria maritima) did not show AChE inhibitory activity.

Changes in fatty acyl chain composition of rat heart phospholipids induced by noradrenaline.

The effect of noradrenaline on fatty acyl chain composition of the rat heart phospholipids was studied in vivo. The rats received increasing amounts of noradrenaline for 15 days. The noradrenaline stress caused significant alterations in the fatty acyl chain composition of the two major phospholipids in heart muscle, whereas the phospholipid content remained unchanged. In phosphatidylcholine, there was 50% diminution in linoleic acid and a decrease in oleic acid with a concomitant increase in stearic, arachidonic and docosahexaenoic acids. In phosphatidylethanolamine, the docosahexaenoic acid increased by 25% accompanied by a decrease in oleic and arachidonic acids. The possible causes and consequences of these changes are discussed.

Polyunsaturated fatty acids in heart muscle and α1-adrenoceptor binding properties

Abstract Modifications of membrane phospholipids and binding characteristics of adrenoceptors by hydrocortisone and epinephrine were examined in sarcolemmal preparation from rat heart muscle. The influence of hydrocortisone and epinephrine on the fatty acid composition of membrane phospholipids and the affinity ( 1 K d ) and number of binding sites (Bmax) of α1- and β-adrenoceptors was studied in male Wistar rats treated daily for 7 days with the hormones. The α1- and β-adrenoceptors were characterized by using the antagonist ligands [3H]prazosin and [3H]dihydroalprenolol, respectively. Administration of the hormones altered significantly the composition of fatty acids, decreased linoleic acid (18:2(n − 6)) level of both phosphatidylcholine and phosphatidylethanolamine, and increased arachidonic acid (20:4(n − 6)) level of phosphatidylcholine and docosahexaenoic acid (22:6(n − 3)) level in both phosphatidylcholine and phosphatidylethanolamine. The binding sites of α1-adrenoceptors were of high affinity in the control group. Following administration of the hormones Kd of α1-adrenoceptors increased markedly. The number of α1-adrenoceptors binding sites did not change significantly due to the hormones. In contrast, while the hormone treatments did not alter the affinity of the β-adrenoceptors the number of binding sites were significantly decreased by the hormones. The results indicate that the decrease in affinity of α1-adrenoceptors and the down-regulation of β-adrenoceptors is accompanied by alteration in percentage fatty acid compositions of phosphatidylethanolamine and phosphatidylcholine in cardiac muscle.

Neonatal changes in fatty acid profile of phospholipids in rat heart muscle

The fatty acid composition of rat heart phospholipids was examined during the neonatal and postnatal period. The rats were killed on days 1, 7, 14 and 21 after birth and at the ages of 2 and 6 months. The fatty acyl chain composition of the two major phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) changed significantly during the first 2 months. In PC there was a marked and immediate increase in stearic acid, a significant but transient increase in arachidonic acid and late increase in linoleic acid content. In PE there was an immediate increase in stearic acid and docosahexaenoic acid, followed by a late increase in linoleic acid content. The observed alterations in fatty acid composition of heart muscle phospholipids resemble changes induced by repeated administration of norepinephrine and subsequent recovery. Neonatal stress and increased cardiac function play an important role in the modification of the fatty acid composition of rat heart muscle phospholipids during early development.

Effects of ageing and adrenergic stimulation on α1- and β-adrenoceptors and phospholipid fatty acids in rat heart

Abstract The purpose of this study was to examine the influence of ageing on the alterations in binding characteristics of adrenoceptors and membrane phospholipid fatty acids in rat heart following repeated administration of epinephrine. The maximal number of binding sites ( B max ) and dissociation constant ( K d ) of [ 3 H]prazosin and [ 3 H]dihydrpalprenolol binding to α 1 - and β-adrenoceptors, respectively, changed significantly during ageing. The downregulation of α 1 - and β-adrenoceptors after repeated epinephrine administration for one week, did not differ with age, but the response of the affinity (1/ K d ) of both α 1 - and β-adrenoceptors to epinephrine treatment was age dependent. In 3-month-old rats the affinity of α 1 -adrenoceptors was decreased after epinephrine treatment but the affinity of β-adrenoceptors was unchanged. In 10- and 23-month-old rats the affinity of β-adrenoceptors decreased after epinephrine treatment but the affinity of α 1 -adrenoceptors did not change. During ageing the linoleic acid (18:2(n-6)) level decreased in phosphatidylcholine and the arachidonic acid (20:4(n-6)) level increased in phosphatidylcholine and phosphatidylethanolamine. After epinephrine administration the 18:2(n-6) level decreased and the docosahexaenoic acid (22:6(n-3)) level increased in phosphatidylcholine and phosphatidylethanolamine and those changes were not age dependent. The 20:4(n-6) level increased in phosphatidylcholine after epinephrine administration, but that increase was smaller in old than in young rats. The results show that both ageing and epinephrine administration simultaneously modify the fatty acid composition of membrane phospholipids and the binding properties of α 1 - and β-adrenoceptors in rat heart.

Modification of the fatty acid composition of rat heart sarcolemma with dietary cod liver oil, corn oil or butter

The effect of dietary cod liver oil, corn oil or butter upon the lipid composition of cardiac sarcolemma and the activity of sarcolemmal Na+, K+ ATPase was examined in male Wistar rats. The cod liver oil diet caused significant changes in the fatty acid composition of the major phospholipids of sarcolemma, phosphatidyl choline and phosphatidyl ethanolamine. In both these phospholipids arachidonic acid, 20:4 (n - 6) was reduced by about 50% compared to rats fed butter or corn oil and was replaced by the (n - 3) fatty acids eicosapentaenoic and docosahexaenoic acids. The corn oil diet caused a significant diminution in the oleic acid content of phosphatidyl choline and elevation of linoleic acid in phosphatidyl ethanolamine. The phospholipid class composition, total phospholipid fatty acid content and cholesterol content of sarcolemma were not altered by the diets used. The activity of Na+, K+ ATPase in the cardiac sarcolemma was not significantly changed by the different diets.