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1.
Differential utilization of eicosapentaenoic acid and docosahexaenoic acid in human plasma 总被引:1,自引:0,他引:1
It has recently been shown that the ω3 fatty acid status in humans can be predicted by the concentration of eicosapentaenoic
(EPA) and docosahexaenoic (DHA) acids in plasma phospholipids [Bjerve, K.S., Brubakk, A.M., Fougner, K.J., Johnsen, H., Midjthell,
K., and Vik, T. (1993)Am. J. Clin. Nutr., in press]. In countries with low intake of ω3 fatty acids, the level of EPA in plasma phospholipids is often only about
one-fifth the concentration of DHA. The purpose of this study was to investigate whether this difference in the concentration
of these two fatty acids was due to a selective loss of EPA relative to DHA or to a lower dietary intake of EPA. Seven female
volunteers ingested four grams of MaxEPA daily for 2 wk and in the following 4 wk they ate a diet almost completely devoid
of the long-chain ω3 fatty acids. The concentrations of the ω3 fatty acids in the plasma cholesteryl esters, triglycerides
and phospholipids and the high density lipoprotein phospholipids were examined at weekly intervals throughout the study. There
was a more rapid rise in the concentration of EPA than in DHA levels in the supplementation period in all lipid fractions,
but there was a disproportionate rise in DHA relative to EPA in the plasma lipids compared with the ratio in the supplement.
In the depletion phase there was a rapid disappearance of EPA from all fractions, such that pre-trial levels were reached
by one week post-supplementation. The disappearance of DHA was slower, particularly for the plasma phospholipids: at 4 wk
post-supplementation, the DHA concentration in this fraction was still 40% above the pre-trial value. It is suggested that
the low plasma EPA values relative to DHA are the result of increased β-oxidation of EPA and/or low dietary intake, rather
than a rapid conversion of EPA to DHA. One practical result of this experiment is that, compared with DHA, the maintenance
of increased EPA levels in plasma (and therefore tissues) would require constant inputs of EPA due to its more rapid loss
from the plasma. 相似文献
2.
Concentrates of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were heated at 140–240 °C for 2–8 h under nitrogen. The trans isomers were analysed by gas chromatography‐mass spectrometry on a BPX‐70 cyanopropyl column. All geometrical isomers of EPA and DHA with one trans double bond were observed. The rate constants (k) for the isomerisation of the all‐cis isomers were calculated and found to be higher than previously reported for linoleic acid and α‐linolenic acid. Arrhenius plots showed a linear relationship between ln k and the reciprocal absolute temperature above 180 °C. The distribution patterns of isomers with one trans double bond are approximately constant up to a degree of isomerisation of 25%. The degree of isomerisation can therefore be estimated from selected trans peaks. 相似文献
3.
Effects of eicosapentaenoic acid and docosahexaenoic acid on plasma membrane fluidity of aortic endothelial cells 总被引:10,自引:0,他引:10
We investigated the relative effects of n−3 eicosapentaenoic acid (EPA, 20∶5n−3) and docosahexaenoic acid (DHA, 22∶6n−3) on
the plasma membrane fluidity of endothelial cells (EC) cultured from the thoracic aorta by determining fluorescence polarization
of 1,6-diphenyl-1,3,5-hexatriene (DPH) and its cationic derivative trimethylamino-DPH (TMA-DPH). Fluidity assessed by TMA-DPH
demonstrated no significant differences in plasma membranes of vehicle (dimethyl sulfoxide; DMSO)-, EPA-, and DHA-treated
EC. Plasma membrane fluidity assessed by DPH polarization, however, was significantly higher in the order of DHA>EPA>DMSO.
Total cholesterol content decreased significantly by 28.4 and 15.9% in the plasma membranes of DHA- and EPA-treated cells,
respectively. Total phospholipid content remained unaltered in the plasma membranes of the three groups of cells; however,
the molar ratio of total cholesterol to phospholipid decreased significantly only in the membranes of DHA-treated EC. The
unsaturation index in the plasma membranes of EPA- and DHA-treated cells increased by 35.7 and 64.3%, respectively, compared
with that in the plasma membranes of control cells. The activities of catalase and glutathione peroxidase in the whole-cell
homogenates, and levels of lipid peroxides in either the whole-cell homogenates or in plasma membrane fractions were not altered
in EPA- or DHA-treated EC. These results indicate that the influence of DHA is greater than that of EPA in increasing plasma
membrane fluidity of vascular EC. We speculate that the greater effect of DHA compared to EPA is due to its greater ability
to decrease membrane cholesterol content or the cholesterol/phospholipid molar ratio, or both, and also to its greater ability
in elevating the unsaturation index in the plasma membranes of EC. 相似文献
4.
Normal, healthy male volunteers (n=6) were fed diets [high docosahexaenoic acid-DHA] containing 6 g/d of DHA for 90 d. The stabilization (low-DHA) diet contained
less than 50 mg/d of DHA. A control group (n=4) remained on the low-DHA diet for the duration of the study (120 d). Blood samples were drawn on study days 30 (end of
the stabilization period), 75 (midpoint of the intervention period), and 120 (end of the intervention period). Adipose tissue
(AT) samples were taken on days 30 and 120. The plasma cholesterol (C), low density lipoprotein (LDL)-C and apolipoproteins
(apo) [Al, B, and lipoprotein (a)] were unchanged after 90 d, but the triglycerides (TAG) were reduced from a mean value of
76.67±24.32 to 63.83±16.99 mg/dL (n=6, P<0.007 using a paired t-test) and the high density lipoprotein (HDL)-C increased from 34.83±4.38 mg/dL to 37.83±3.32 mg/dL (n=6, P<0.017 using a paired t-test). The control group showed no significant reduction in plasma TAG levels. Apo-E, however, showed a marked increase in
the volunteers’ plasma after 90 d on the high-DHA diet, from 7.06±4.47 mg/dL on study day 30 to 12.01±4.96 mg/dL on study
day 120 (P<0.002 using a paired t-test). The control subjects showed no significant change in the apo-E in their plasma (8.46±2.90 on day 30 vs. 8.59±2.97
on day 120). The weight percentage of plasma DHA rose from 1.83±0.22 to 8.12±0.76 after 90 d on the high-DHA diet. Although
these volunteers were eating a diet free of eicosapentaenoic acid (EPA), plasma EPA levels rose from 0.38±0.05 to 3.39±0.52
(wt%) after consuming the high-DHA diet. The fatty acid composition of plasma lipid fractions—cholesterol esters, TAG, and
phospholipid—showed marked similarity in the enrichment of DHA, about 10%, after the subjects consumed the high-DHA diet.
The DHA content of these plasma lipid fractions varied from less than 1% (TAG) to 3.5% (phospholipids) at baseline, study
day 30. EPA also increased in all plasma lipid fractions after the subjects consumed the high-DHA diet. There were no changes
in the plasma DHA or EPA levels in the control group. Consumption of DHA also caused an increase in AT levels of DHA, from
0.10±0.02 to 0.31±0.07 (wt%) (n=6, P<0.001 using a paired t-test), but the amount of EPA in their AT did not change. Thus, dietary DHA will lower plasma TAG without EPA, and DHA is
retroconverted to EPA in significant amounts. Dietary DHA appears to enhance apo-E synthesis in the liver. It appears that
DHA can be a safe and perhaps beneficial supplement to human diets. 相似文献
5.
6.
Donald L. Smith Anthony L. Willis Ngoc Nguyen Debra Conner Shaye Zahedi Judy Fulks 《Lipids》1989,24(1):70-75
Studies in man and laboratory animals suggest that ω3 polyunsaturated fatty acid consituents of fish oils have antiatherosclerotic
properties. We have studied the effects of several such polyunsaturated fatty acids for ability to modify the in vitro release
of mitogens from human platelets. Such mitogens may produce the fibroproliferative component of atherosclerotic plaques. Both
5,8,11,14,17-eicosapentaenoic acid (20∶5ω3) and 4,7,10,13,-16,19-docosahexaenoic acid (22∶6ω3), major constituents of fish
oils, inhibited adenosine diphosphate-induced aggregation of platelets and the accompanying release of mitogens. These effects
are dose dependent. Linolenic acid (18∶3ω3), the biosynthetic precursor of eicosapentaenoic acid, also inhibited platelet
aggregation and mitogen release. Eicosapentaenoic acid also inhibited mitogen release from human monocyte-derived macrophages,
which, in vivo, are an additional source of mitogens during atherogenesis.
Potent inhibition of human platelet aggregation and mitogen release was also seen with dihomo-γ-linolenic acid (8,11,14-eicosatrienoic
acid 20∶3ω6), whose levels are reportedly elevated in Eskimos subsisting on marine diets.
We conclude that diets that elevate plasma and/or tissue levels of eicosapentaenoic acid, docosahexaenoic acid and dihomo-γ-linolenic
acid precursor γ-linolenic acid (18∶3ω6) may exert antiatherosclerotic effects by inhibiting the release of mitogens from
platelets and other cells. 相似文献
7.
It was of interest to investigate the influence of both high doses of eicosapentaenoic acid (EPA) and low doses of 2-or 3-methylated
EPA on the antioxidant status, as they all cause hypolipidemia, but the dose required is quite different. We fed low doses
(250 mg/d/kg body wt) of different EPA derivatives or high doses (1500 mg/d/kg body wt) of EPA and DHA to rats for 5 and 7
d, respectively. The most potent hypolipidemic EPA derivative, 2,2-dimethyl-EPA, did not change the malondialdehyde content
in liver or plasma. Plasma vitamin E decreased only after supplementation of those EPA derivatives that caused the greatest
increase in the fatty acyl-CoA oxidase activity. Fatty acyl-CoA oxidase activity increased after administration of both EPA
and DHA at high doses. High doses of EPA and DHA decreased plasma vitamin E content, whereas only DHA elevated lipid peroxidation.
In liver, however, both EPA and DHA increased lipid peroxidation, but the hepatic level of vitamin E was unchanged. The glutathione-requiring
enzymes and the glutathione level were unaffected, and no significant changes in the activities of xanthine oxidase and superoxide
dismutase were observed in either low-or high-dose experiments. In conclusion, increased peroxisomal β-oxidation in combination
with high amounts of polyunsaturated fatty acids caused elevated lipid peroxidation. At low doses of polyunsaturated fatty
acids, lipid peroxidation was unchanged, in spite of increased peroxisomal β-oxidation, indicating that polyunsaturation is
the most important factor for lipid peroxidation. 相似文献
8.
In rhesus monkeys, maternal n-3 fatty acid deficiency during pregnancy produces infant monkeys deficient in n-3 fatty acids
at birth. These results stimulated current experiments to find out if n-3 fatty acids from fish in the diets of pregnant women
would influence the concentration of docosahexaenoic acid (DHA, 22:6 n-3) in the newborn human infant.
Fifteen healthy pregnant women were enrolled to receive a 9-wk dietary supplementation of n-3 fatty acids from the 26th to
the 35th wk of pregnancy. Sixteen pregnant women were not supplemented and served as controls. n-3 Fatty acid supplementation
consisted of sardines and additional fish oil, which provided a total of 2.6 g of n-3 fatty acids per day (d) for the 9-wk
period of supplementation. This included 1.01 g DHA.
The end point of this study was the blood concentrations of DHA in the newborn infant. DHA in maternal red blood cells increased
from 4.69% of total fatty acids to 7.15% at the end of the supplement period and at the time of delivery decreased (as expected)
to 5.97% of total fatty acids. Maternal plasma showed a similar change from 2.12 to 3.51% of total fatty acids and then decreased
to 2.35%. Levels of DHA in plasma and red blood cells of unsupplemented mothers did not change during the same time period.
Levels of DHA in blood of newborn infants differed greatly in infants born from n-3-supplemented mothers compared with control
infants. In red blood cells, DHA was 7.92% of total fatty acids compared with 5.86% (control infants). Plasma values showed
a similar difference: 5.05% vs. 3.47% (controls). In n-3-supplemented infants, DHA concentrations were 35.2% higher than in
control infants in red blood cells and 45.5% higher in plasma.
These data indicate the importance of maternal dietary n-3 fatty acids and, in particular, maternal dietary DHA in promoting
higher concentrations of DHA in the blood of the newborn infant. 相似文献
9.
Preparation of highly purified concentrates of eicosapentaenoic acid and docosahexaenoic acid 总被引:1,自引:9,他引:1
Harald Breivik Gudmundur G. Haraldsson Björn Kristinsson 《Journal of the American Oil Chemists' Society》1997,74(11):1425-1429
Because of the complexity of marine lipids, polyunsaturated fatty acid (PUFA) derivatives in highly purified form are not
easily prepared by any single fractionation technique. The products are usually prepared as the ethyl esters by esterification
of the body oil of fat fish species and subsequent physicochemical purification processes, including short-path distillation,
urea fractionation, and preparative chromatography. Lipase-catalyzed transesterification has been shown to be an excellent
alternative to traditional esterification and short-path distillation for concentrating the combined PUFA-content in fish
oils. At room temperature in the presence of Pseudomonas sp. lipase and a stoichiometric amount of ethanol without any solvent, efficient transesterification of fish oil was obtained.
At 52% conversion, a concentrate of 46% eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) was obtained in excellent
recovery as a mixture of mono-, di-, and triacylglycerols. The latter can be easily separated from the saturated and monounsaturated
ethyl esters and converted into ethyl esters either by conventional chemical means or enzymatically by immobilized Candida antarctica lipase. Urea-fractionation of such an intermediary product can give an EPA+DHA content of approximately 85%. 相似文献
10.
The aim of this study was to investigate the possibility of a relationship between plasma homocysteine (Hcy) and phospholipid
FA (PUFA) in healthy Australian males. One hundred thirty six healthy male subjects aged 20–55 yr were recruited from the
Melbourne metropolitan area. Each volunteer completed a semiquantitative food frequency questionnaire and gave a blood sample.
Plasma Hcy concentrations were determined by an established HPLC method; the plasma phospholipid FA were determined by standard
methods. Plasma Hcy concentration was significantly negatively correlated with plasma phospholipid concentration of the PUFA
20∶5n−3 (r=−0.226, P=0.009), 22∶5n−3 (r=−0.182, P=0.036), 22∶6n−3 (r=−0.286, P=0.001), total n−3 (r=−0.270, P=0.002) and the ratio n−3/n−6 PUFA (r=−0.265, P=0.002), and significantly positively correlated with 20∶4n−6 (r=0.180, P=0.037). In the partial correlation analysis, after controlling for serum vitamin B12 and folate concentration, plasma Hcy was significantly negatively correlated with the plasma phospholipid concentration of
22∶6n−3 (r=−0.205, P=0.019), total n−3 (r=−0.182, P=0.038) and the ratio n−3/n−6 PUFA (r=−0.174, P=0.048). Evidence indicates that an increased concentration of n−3 PUFA in tissues has a beneficial effect on cardiovascular
health. Our findings provide further evidence that increased consumption of dietary n−3 PUFA increases the concentration of
n−3 PUFA in plasma phospholipid, which is associated with a protective effect on cardiovascular diseases and lower plasma
Hcy levels. The mechanism that might explain the association between plasma 22∶6n−3 and Hcy levels is not clear. 相似文献
11.
Eicosapentaenoic acid (EPA, 20∶5n−3) and docosahexaenoic acid (DHA, 22∶6n−3) in free fatty acids (FFA) derived from saponified
menhaden oil were concentrated by the solubility differences of FFA-salts in organic solvent. FFA-salts were formed by adding
NaOH to a solution containing FFA. A Buchner funnel was used to separate solid phases from liquids containing FFA-salts. FFA
that are rich in EPA and DHA can be recovered from the liquid phase by the addition of 12 N HCl. The effects of reaction time,
the amount of NaOH, and solvent used on the concentration of EPA and DHA were systematically investigated. With a total volume
of 112 mL, made up of 1.85% 15 N NaOH, 88.1% acetone, and 10.0% FFA, a reaction temperature of 30°C, and a reaction time of
1 h, the resulting liquid phase contained 65.4 wt% EPA and DHA, with a corresponding yield of 41.5%. By replacing the acetone
with a mixture of 45% acetone and 55% acetonitrile and then storing the liquid phase at −70°C overnight, the content and yield
of EPA and DHA in the final liquid phase were 61.4 wt% and 66.2%, respectively. 相似文献
12.
Livar Frøyland Hege Vaagenes Daniel K. Asiedu Alexis Garras Øyvind Lie Rolf K. Berge 《Lipids》1996,31(2):169-178
Fish oils rich in n-3 fatty acids have been shown to decrease plasma lipid levels, but the underlying mechanism has not yet
been elucidated. This investigation was performed in order to further clarify the effects of purified ethyl esters of eicosapentaenoic
acid (EPA-EE) and docosahexaenoic acid (DHA-EE) on lipid metabolism in rats. The animals were fed EPA-EE, DHA-EE, palmitic
acid, or corn oil (1 g/kg/d) by orogastric intubation along with a chow background diet for three months. At the end the animals
were sacrificed. Plasma and liver lipids were measured, as well as lipid-related enzyme activities and mRNA levels. The fatty
acid composition of plasma and different tissues was also determined. This study shows that, compared to the corn oil control,
EPA-EE and DHA-EE lowered plasma cholesterol level, whereas only EPA-EE lowered the amount of plasma triacylglycerol. In liver
peroxisomes, both EE preparations increased fatty acyl-CoA oxidase FAO activities, and neither altered 3-hydroxy-3-methylglutaryl
(HMG)-CoA reductase activities. In liver microsomes, EPA-EE raised HMG-CoA reductase and acyl-CoAicholesterol acyltransferase
activities, whereas DHA-EE lowered the former and did not affect the latter. Neither product altered mRNA levels for HMG-CoA
reductase, low density lipoprotein-receptor, or low density lipoprotein-receptor related protein. EPA-EE lowered plasma triacylglycerol,
reflecting lowered very low density lipoprotein secretion, thus the cholesterol lowering effect in EPA-EE-treated rats may
be secondary to the hypotriacylglycerolemic effect. An inhibition of HMG-CoA reductase activity in DHA-EE treated rats may
contribute to the hypocholesterolemic effect. The present study reports that 20∶5n-3, and not 22∶6n-3, is the fatty acid primarily
responsible for the triacylglycerol lowering effect of fish oil. Finally, 20∶5n-3 was not converted to 22∶6n-3, whereas retroconversion
of 22∶6n-3 to 20∶5n-3 was observed. 相似文献
13.
Eiji Kamio Yu Seike Hidekazu Yoshizawa Tsutomu Ono 《American Institute of Chemical Engineers》2010,56(8):2163-2172
The liquid–liquid extraction dynamics of an ethyl ester of docosahexaenoic acid (DHA‐Et) with silver ion was investigated. The kinetic model was derived according to the following stepwise processes: Diffusion of DHA‐Et across the organic film, complex‐formation between DHA‐Et and silver ion at the interface, and diffusion of extracted complex across the aqueous film. The kinetic parameters for the complex‐formation reaction were determined from the investigation with the stirred transfer cell. With the proposed model and determined parameters, we predicted the uptakes of DHA‐Et for the extraction system utilizing a slug flow prepared by a microchip. The calculated uptakes showed good correlation to the experimental data. The theoretical investigation suggested that the fast equilibration realized for the slug flow extraction system was due to the large specific interfacial area of the slug caused by the presence of wall film and the thin liquid film caused by the internal circulation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 相似文献
14.
Svein A. Mjøs 《European Journal of Lipid Science and Technology》2008,110(6):547-553
A polyethylene glycol (PEG) stationary phase was evaluated for the separation of mono‐trans isomers of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) methyl esters. The resolution patterns were compared to patterns achieved with previously applied conditions on a cyanopropyl phase. There were no overlaps between all‐cis EPA/DHA and their mono‐trans isomers on the PEG phase. Because of overlap between 22:0 and 22:1 isomers, the PEG column is not a good choice for analyses of EPA trans isomers in crude fish oils. However, if the saturated and monounsaturated fatty acids are not present in significant amounts, PEG can be a better choice than cyanopropyl columns. 相似文献
15.
To better understand the mode of action of ω3 fatty acids in cell membranes, human foreskin fibroblasts were grown in serum-free
medium supplemented with 50 μM oleic acid linoleic acid, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), and the
effects on membrane composition, fluorescence polarization and enzyme activities were followed. The cells were enriched with
EPA and DHA up to 7 and 13% of total lipids, respectively, of which >95% was associated with phospholipids. In addition, the
concentration of 22∶5n−3 increased with both EPA and DHA to 7.5, and 2.1% of the total fatty acids, respectively. When compared
to controls (oleic acid), cells treated with DHA showed a decrease in cholesterol, phospholipids, arachidonic acid (AA) and
free cholesterol/phospholipid ratio (P<0.05). In the presence of EPA, only decreases in AA and cholesterol were significant (P<0.05). Membrane fluidity, assessed by fluorescence anisotropy, was increased 16% in cells enriched with DHA (P<0.05), but showed no change with EPA or linoleic acid. There was an increase in membrane-associated 5′-nucleotidase (+27%)
and adenylate cyclase (+19%) activities (P<0.05), in DHA-enriched, but not in EPA-enriched cells, when compared with oleate controls. The studies show that incorporation
of DHA, but not EPA, into cell membranes of fibroblasts alters membrane biophysical characteristics and function. We suggest
that these two major n−3 fatty acids of fish oils have differential effects on cell membranes, and this may be related to
the known differences in their physiological effects. 相似文献
16.
Eicosapentaenoic acid and docosahexaenoic acid production potential of microalgae and their heterotrophic growth 总被引:9,自引:0,他引:9
Twenty microalgal strains were investigated in photoautotrophic flask cultures for their potential for eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA) production. The highest EPA proportion (% of total fatty acids) was produced by Monodus subterraneus UTEX 151 (34.2%), followed by Chlorella minutissima UTEX 2341 (31.3%) and Phaeodactylum tricornutum UTEX 642 (21.4%). The highest DHA proportion (% of total fatty acids) was obtained in Crypthecodinium cohnii UTEX L1649 (19.9%), followed by Amphidinium carterae UTEX LB 1002 (17.0%) and Thraustochytrium aureum ATCC 28211 (16.1%). Among the 20 strains screened, the EPA yield was high in M. subterraneus UTEX 151 (96.3 mg/L), P. tricornutum UTEX 642 (43.4 mg/L), Chl. minutissima UTEX 2341 (36.7 mg/L), and Por. cruentum UTEX 161 (17.9 mg/L) owing to their relatively high biomass concentrations. The DHA yield was high in C. cohnii UTEX L1649 (19.5 mg/L) and A. carterae UTEX LB 1002 (8.6 mg/L). Heterotrophic growth of these 20 microalgae was also tested on two different carbon sources, acetate
and glucose. All microalgae except Nannochloropsis oculata UTEX LB 2164 showed growth on glucose (5 g/L) under heterotrophic conditions. Twelve of them could grow heterotrophically
when acetate (1 g/L) was used as their sole carbon and energy source. 相似文献
17.
Gabriella Calviello Paola Palozza Piergiorgio Franceschelli Gianna Maria Bartoli 《Lipids》1997,32(10):1075-1083
In view of the promising future for use of n-3 polyunsaturated fatty acids (PUFA) in the prevention of cancer and cardiovascular
diseases, it is necessary to ensure that their consumption does not result in detrimental oxidative effects. The aim of the
present work was to test a hypothesis that low doses of eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) do not induce
harmful modifications of oxidative cell metabolism, as modifications of membrane fatty acid composition occur. Wistar rats
received by gavage oleic acid, EPA, or DHA (360 mg/kg body weight/day) for a period of 1 or 4 wk. Fatty acid composition and
α-tocopherol content were determined for plasma, red blood cell (RBC) membranes, and liver, kidney, lung, and heart microsomal
membranes. Susceptibility to oxidative stress induced by tert-butylhydroperoxide was measured in RBC. EPA treatment increased EPA and docosapentaenoic acid (DPA) content in plasma and
in all the membranes studied. DHA treatment mainly increased DHA content. Both treatments decreased arachidonic acid content
and n-6/n-3 PUFA ratio in the membranes, without modifying the Unsaturation Index. No changes in tissue α-tocopherol content
and in RBC susceptibility to oxidative stress were induced by either EPA or DHA treatment. The data suggest that EPA and DHA
treatments can substantially modify membrane fatty acids, with-out increasing susceptibility to oxidative stress, when administered
at low doses. This opens the possibility for use of low doses of n-3 PUFA for chemoprevention without risk of detrimental
secondary effects. 相似文献
18.
Ann‐Marie Lyberg Dietlind Adlercreutz Patrick Adlercreutz 《European Journal of Lipid Science and Technology》2005,107(5):279-290
Regioselective incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into phosphatidylcholine (PC) was carried out using enzymatic and chemical synthesis. Incorporation at the sn‐1 position was successfully achieved by lipase‐catalysed esterification of 2‐palmitoyl‐lysophosphatidylcholine (LPC), although in most cases, the enzymes incorporated EPA and DHA at lower rates than other fatty acids. For the incorporation of DHA, Candida antarctica lipase B was the only useful enzyme, while incorporation of EPA was efficiently carried out using either this enzyme or Rhizopus arrhizus lipase. The highest yields in the lipase‐catalysed reactions were obtained at the lowest water activity (close to 0). However, by carrying out the reactions at a higher water activity of 0.22, more EPA and DHA were incorporated. Esterification of 2‐palmitoyl‐LPC with pure EPA at this water activity converted 66 mol‐% of LPC to PC using Rhizopus arrhizus lipase as catalyst. When the fatty acid was DHA and the catalyst Candida antarctica lipase B, 45 mol‐% of PC was obtained. For incorporation of EPA and DHA at the sn‐2 position, phospholipase A2 was used, but the reaction was very slow. Chemical coupling of 1‐palmitoyl‐LPC and EPA or DHA was more efficient, resulting in complete conversion of LPC. 相似文献
19.
Thorsten U. Sauerwald David L. Hachey Craig L. Jensen Huiming Chen Robert E. Anderson William C. Heird 《Lipids》1996,31(1):S131-S135
The fractional conversion rates of plasma phospholipid α-linolenic acid (18:3n-3) and linoleic acid (18:2n-6) to docosahexaenoic
acid (22:6n-3) and arachidonic acid (20:4n-6), respectively, and the fractional rates of incorporation of 22:6n-3 and 20:4n-6
into plasma phospholipids were determined in 27 healthy 3-wk-old term infants who had received formulas with ≈16% of fat as
18:2n-6 and 0.4% (n=6), 1.0% (n=11), or 3.2% (n=10) as 18:3n-3 from birth. The infants were given a single dose of both [U-13C] 18:2n-6 and [U-13C]18:3n-3 with a feeding, and blood samples were collected 8, 12, and 24 h afterward for determination of the isotopic enrichments
of the [M+18] isotopomers of plasma phospholipid fatty acids by negative chemical ionization gas chromatography/mass spectrometry.
A simple precursor/product compartmental model was used to estimate fractional rates of conversion and incorporation. All
infants converted 18:3n-3 to 22:6n-3 and 18:2n-6 to 20:4n-6. Although the fractional rate of conversion of 18:3n-3 to 22:6n-3
did not differ among groups, the fractional rate of incorporation of 22:6n-3 into the plasma phospholipid fraction was greater
in infants who received 3.2% vs. 0.4% or 1.0% 18:3n-3 (4.1±2.2 vs 1.6±1.5 or 2.0±1.0% of the plasma phospholipid 22:6n-3 pool
daily). The fractional rate of conversion of 18:2n-6 to 20:4n-6 was less in infants who received the 3.2% 18:3n-3 intake (0.4±0.3%
of the plasma phospholipid 18:2n-6 pool daily vs. 1.1±0.7% and 0.8±0.5% in those who received 0.4 and 1.0% 18:3n-3, respectively).
The fractional rate of incorporation of 20:4n-6 into plasma phospholipid also was less in the 3.2% vs. the 0.4 and 1.0% 18:3n-3
groups (2.7±1.4% vs. 5.9±2.6 and 4.4±1.7%, respectively, of the plasma phospholipid 20:4n-6 pool daily). 相似文献
20.
The utilization of dietary docosahexaenoic acid (DHA; 22:6n−3) as a source of eicosapentaenoic acid (EPA; 20:5n−3) via retroconversion was investigated in both vegetarians and omnivores. For this purpose, an EPA-free preparation of DHA was
given as a daily supplement (1.62 g DHA) over a period of 6 wk. The dietary supplement provided for a marked increase in DHA
levels in both serum phospholipid (from 2.1 to 7.1 mol% in vegetarians and 2.2 to 7.6 mol% in omnivores) and platelet phospholipid
(from 1.1 to 3.4 mol% in vegetarians and 1.4 to 3.9 mol% in omnivores). EPA levels rose to a significant but much lesser extent,
while 20:4n−6, 22:5n−6, and 22:5n−3 all decreased. Based on the serum phospholipid data, the retroconversion of DHA to EPA
in vivo was estimated to be 9.4% overall with no significant difference between omnivores and vegetarians. 相似文献