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1.
The hypocholesterolemic efficacies of various polyunsaturated fatty acids were compared in rats given cholesterol-enriched
diets.Oenothera biennis Linn oil (OBLO, linoleic +γ-linolenic), sunflower oil (linoleic), palm oil (PLO, oleic+linoleic), soybean oil (linoleic+α-linolenic),
high-oleic safflower oil (oleic+linoleic), or mixed oil (linoleic+α-linolenic) was added to the diet at 200 g/kg (20% groups).
OBLO was also added at 100 g/kg diet (10% group). The serum total and very low density lipoprotein+intermediate lipoprotein+low
density lipoprotein cholesterol concentrations of the 10 and 20% OBLO groups were consistently lower than those in the other
groups. The liver cholesterol concentration in the PLO group was lower in all groups. The liver cholesterol concentrations
in the 10 and 20% OBLO groups were also lower than in the other groups. There were no significant differences in the fecal
neutral sterol and bile acid extraction among groups. 相似文献
2.
Fukushima M Ohhashi T Ohno S Saitoh H Sonoyama K Shimada K Sekikawa M Nakano M 《Lipids》2001,36(3):261-266
Hypocholesterolemic effects in older animals after long-term feeding are unknown. Therefore, aged rats (24 wk of age) fed
a conventional diet were shifted to diets containing 10% perilla oil [PEO; oleic acid+linoleic acid+α-linolenic acid; n−6/n−3,
0.3; polyunsaturated fatty acid/saturated fatty acid (P/S), 9.6], borage oil [oleic acid+linoleic acid+α-linolenic acid; n−6/n−3,
15.1; P/S, 5.3], evening primrose oil (FPO; linoleic acid+γ-linolenic acid; P/S, 10.5), mixed oil (MIO; oleic acid+linoleic
acid+γ-linolenic acid+α-linolenic acid; n−6/n−3, 1.7; P/S, 6.7), or palm oil (PLO; palmitic acid+oleic acid+linoleic acid;
n−6/n−3, 25.3; P/S, 0.2) with 0.5% cholesterol for 15 wk in this experiment. There were no significant differences in the
food intake and body weight gain among the groups. The liver weight in the PEO (n−6/n−3, 0.3) group was significantly higher
than those of other groups in aged rats. The serum total cholesterol and very low density lipoprotein (VLDL) +intermediate
density lipoprotein (IDL)+low density lipoprotein (LDL)-cholesterol concentrations of the PLO (25.3) group were consistently
higher than those in the other groups. The serum high density lipoprotein cholesterol concentrations of the PEO (0.3) and
EPO groups were significantly lower than in the other groups at the end of the 15-wk feeding period. The liver cholesterol
concentration of the PLO (25.3) group was significantly higher than those of other groups. There were no significant differences
in the hepatic LDL receptor mRNA level among the groups. Hepatic apolipoprotein (apo) B mRNA levels were not affected by the
experimental conditions. The fecal neutral steroid excretion of the PLO (25.3) group tended to be low compared to the other
groups. The results of this study demonstrate that both n\t-6 fatty acid and n\t-3 fatty acids such as \gg-linolenic acid
and \ga-linolenic acid inhibit the increase of serum total cholesterol and VLDL+IDL+LDL-cholesterol concentrations of aged
rats in the presence of excess cholesterol in the diet compared with dietary saturated fatty acid. 相似文献
3.
The hypocholesterolemic efficacy of various polyunsaturated fatty acids was compared in rats given cholesterol-enriched diets.
Capybara oil (CO, linoleic+α-linolenic acids), horse oil (HO, α-linolenic acid), and sardine oil (SO, eicosapentaenoic+docosahexaenoic
acids) were added to diets at 50 g/kg. The weight gain, food intake, and liver weight in the CO-fed group were significantly
higher than those in other groups during the 6-wk experimental period. The serum total and very low density lipoprotein (VLDL)+intermediate
density lipoprotein (IDL)+low density lipoprotein (LDL) cholesterol concentrations of the CO-fed and SO-fed groups were significantly
lower than in the HO-fed group after 6 wk. The serum high density lipoprotein cholesterol concentration in the SO-fed group
was significantly higher than that in the CO-fed and HO-fed groups. The fecal neutral sterol concentration in the CO-fed group
was reduced significantly compared with the other groups, and the fecal bile acid concentration in the HO-fed group was significantly
higher than that in the SO-fed group. The results of this study demonstrate that CO lowers the serum total cholesterol and
VLDL+IDL+LDL-cholesterol concentrations in the presence of excess cholesterol in the diet as well as SO. 相似文献
4.
Three groups of rats were fed diets with either 10 weight percent (wt%) of evening primrose oil, safflower oil or soybean
oil for 11 weeks. Diets contained 7.1 wt% linoleic acid +0.8 wt% γ-linolenic acid, 7.6 wt% linoleic acid, or 5.3 wt% linoleic
acid +0.7 wt% α-linolenic acid, respectively. In liver mitochondria as well as in heart, dietary γ-linolenic acid did not
affect the fatty acid profiles of phosphatidylcholnes (PC), phosphatidylethanolamines (PE) or cardiolipins (CL), whereas dietary
α-linolenic acid caused an increased formation of (n−3) polyunsaturated fatty acids (PUFA). The liver Δ6− and Δ5-desaturase
activities determined in vitro were not affected by the dietary fats. In brain PE, which are rich in C22− and C20-(n−3) PUFA,
as well as in testes PC and PE, which are rich in (n−6) PUFA, no effects were found from a partial replacement of dietary
linoleic acid with γ-linolenic acid or α-linolenic acid. In kidney PC, PE, phosphatidylinositol (PI) and CL, 20∶3(n−6) was
moderately elevated to ca. 1% following intake of γ-linolenic acid, whereas partial replacement of linoleic acid with α-linolenic
acid was followed by increased deposition of 22∶6(n−3) in PC and PE of testes and kidney. Thus, no general effect of evening
primrose oil on the content of (n−6) PUFA in rat tissue phospholipids was observed, wheras a significant incorporation of
γ-linolenic acid into liver and adipose tissue triglycerides was found. 相似文献
5.
The effects of oil-derived dietary essential fatty acids on the activities of mitchondrial Mn-SOD (manganese-superoxide dismutase)
and cytosolic cupric zinc-superoxide dismutase (Cu/Zn-SOD) were investigated in rat heart. A control group of rats was fed
a stock diet for 29 d, and a second group was fed on a fat-free diet. Three other groups were fed fat-free diets that were
supplemented with (i) borage oil, which is rich in linoleic (18∶2n−6) and γ-linolenic (18∶3n−6) acids, (ii) fungal oil, which
is rich in γ-linolenic, but low in linoleic acid, or (iii) evening primrose oil, which is rich in linoleic acid and low in
γ-linolenic acid. An increase in the percentage composition of arachidonic acid (20∶4n−6) in both the choline and ethanolamine
phospholipids, together with a decrease in linoleic acid in ethanolamine phospholipids, were found in heart membranes after
feeding the rats with diets containing borage oil or fungal oil as compared to those fed the stock diet. The respective activities
of Mn-SOD in rats fed the borage or fungal oil diets were also significantly higher than in rats fed the stock diet alone.
No change in cytosolic Cn/Zn-SOD activity was observed. Dietary supply of linoleic acid-rich evening primrose oil resulted
in an increased proportion of choline phospholipid linoleic acid without any changes in arachidonic acid content or in the
activity of Mn-SOD. By contrast, a reduction in the activity of Mn-SOD was detected in rats fed a fat-free diet. These results
show that the activity of heart mitochondrial Mn-SOD is influenced by dietary essential fatty acids, whereas the activity
of cytosolic Cu/Zn-SOD remained unaffected. 相似文献
6.
Sakayu Shimizu Hiroshi Kawashima Kengo Akimoto Yoshifumi Shinmen Hideaki Yamada 《Journal of the American Oil Chemists' Society》1989,66(3):342-347
Mycelia of arachidonic acid-producing fungi belonging to the genusMortierella were found to convert an oil containing α-linolenic acid to an oil containing 5,8,11,14,17-cis-eicosapentaenoic acid (EPA). This conversion was observed when they were grown in a medium containing the oil, glucose and
yeast extract at 28 C. On the screening of various oils, linseed oil, in which α-linolenic acid amounts to about 60% of the
total fatty acids, was found to be the most suitable for EPA production. Under the optimal culture conditions, a selected
strain,Mortierella alpina 20-17, converted 5.1% of the α-linolenic acid in the added oil into EPA, the EPA production reaching 1.35 g/l of culture
broth (41.5 mg/g dry mycelia). This value corresponded to 7.1% (by weight) of the total fatty acids in the extracted lipids.
The lipid was also found to be rich in arachidonic acid (12.3%). Other major fatty acids in the lipid were palmitic acid (4.4%),
stearic acid (3.2%), oleic acid (13.5%), linoleic acid (13.7%), α-linolenic acid (38.5%) and γ-linolenic acid (0.9%). 相似文献
7.
Shimizu Sakayu Akimoto Kengo Kawashima Hiroshi Shinmen Yoshifumi Yamada Hideaki 《Journal of the American Oil Chemists' Society》1989,66(2):237-241
The mycelial dihomo-γ-linolenic acid content of an arachidonic acid-producing fungus,Mortierella alpina 1S-4, was found to increase, with an accompanying marked decrease in its arachidonic acid content, on cultivation with sesame
oil. The resultant mycelia were found to be a rich source of dihomo-γ-linolenic acid. This unique phenomenon was suggested
to be due to specific repression of the conversion of dihomo-γ-linolenic acid to arachidonic acid by the oil. After fractionation
of the oil with acetone into oil and non-oil fractions, it was found that the effective factor(s) was present in the non-oil
fraction. In a study on optimization of the culture conditions for the production of dihomo-γ-linolenic acid byM. alpina 1S-4, a medium containing glucose, yeast extract and the non-oil fraction was found to be suitable for the production. Under
the optimal conditions in a 50-1 fermentor, the fungus produced 107 mg of dihomo-γ-linolenic acid/g dry mycelia (2.17 g/l
of culture broth). This value accounted for 23.1% of the total fatty acids in the lipids extracted from the mycelia. The mycelia
were also rich in arachidonic acid (53.5 mg/g dry mycelia, 11.2%). Other major fatty acids in the lipids were palmitic acid
(24.1%), stearic acid (7.0), oleic acid (20.1), linoleic acid (6.6) and γ-linolenic acid (4.1).
On leave from Suntory Ltd. 相似文献
8.
The triacylglycerol stereospecific structure was determined for the major plant oils containing ψ-linolenic acid (GLA): evening
primrose oil (EPO), black currant oil (BCO), borage oil (BO), andMucor javanicus fungal oil (MJO). It was found that GLA, although not α-linolenic acid, resisted pancreatic lipase hydrolysis. Therefore,
the 2-position analysis was determined using phospholipase C-generated 1,2-diacylglycerol and phospholipase A2-generated lysophosphatidylcholine. GLA was found to be concentrated in the 3-position of EPO and BCO, the 2-position of BO,
and the 2- and 3-positions of MJO. In BCO, octadecatetraenoic acid (n−3), also a †-6 fatty acid, was distributed similarly
to GLA, but α-linolenic acid was found predominantly in the 1-position. Linoleic acid was nearly evenly distributed in all
positions of EPO and BCO but was concentrated in the 1-position of BO and the 2-position of MJO. Both palmitic and stearic
acids were found predominantly in the 1-position of all of the oils. The results demonstrate similarities and differences
in the positional distribution of fatty acids in GLA-containing oils. 相似文献
9.
Conjugated fatty acids are regularly found in nature and have a history of biogenic activity in animals and humans. A number
of these conjugated fatty acids are microbially produced and have been associated with potent anti-carcinogenic, anti-adipogenic,
anti-atherosclerotic and anti-diabetogenic activities. Therefore, the identification of novel conjugated fatty acids is highly
desirable. In this study, strains of bifidobacteria and propionibacteria previously shown by us and others to display linoleic
acid isomerase activity were assessed for their ability to conjugate a range of other unsaturated fatty acids during fermentation.
Only four, linoleic, α-linolenic, γ-linolenic and stearidonic acids, were converted to their respective conjugated isomers,
conjugated linoleic acid (CLA), conjugated α-linolenic acid (CLNA), conjugated γ-linolenic acid (CGLA) and conjugated stearidonic
acid (CSA), each of which contained a conjugated double bond at the 9,11 position. Of the strains assayed, Bifidobacterium breve DPC6330 proved the most effective conjugated fatty acid producer, bio-converting 70% of the linoleic acid to CLA, 90% of
the α-linolenic acid to CLNA, 17% of the γ-linolenic acid to CGLA, and 28% of the stearidonic acid to CSA at a substrate concentration
of 0.3 mg mL−1. In conclusion, strains of bifidobacteria and propionibacteria can bio-convert linoleic, α-linolenic, γ-linolenic and stearidonic
acids to their conjugated isomers via the activity of the enzyme linoleic acid isomerase. These conjugated fatty acids may
offer the combined health promoting properties of conjugated fatty acids such as CLA and CLNA, along with those of the unsaturated
fatty acids from which they are formed. 相似文献
10.
The fatty acid composition of 16 brands of evening primrose oil (EPO) capsules was determined by capillary gas chromatography.
Fourteen of these EPO brands contained γ-linolenic acid (GLA) levels between 7% and 10% (mean, 8.7; range, 1.9–10.5%) and
there was generally good agreement between the level of GLA claimed by the manufacturer and the level determined by analysis.
Low levels of the monoenes 22∶1 and 24∶1 found in some brands may indicate contamination of EPO with borage oil. 相似文献
11.
Murielle Schmitt-Rozieres Guillaume Vanot Valérie Deyris Louis-Claude Comeau 《Journal of the American Oil Chemists' Society》1999,76(5):557-562
γ-Linolenic acid (Z,Z,Z-6,9,12-octadecatrienoic acid), a very important polyunsaturated fatty acid is found in the free fatty acid fraction prepared
by the hydrolysis of borage oil. Our aim was to enrich this fraction in γ-linolenic acid using selective esterification. Candida rugosa lipase was used as catalyst after immobilization on the following ion-exchange resins: Amberlite IRC50, IRA35, IRA93, and
Duolite A7, A368, A568. In every case, immobilization modified the lipae’s specificity: palmitic, stearic, oleic, and linoleic
acids were preferentially esterified compared to γ-linolenic acid, thus allowing a γ-linolenic acid enrichment of 3.0. 相似文献
12.
The interrelations between linoleic acid (LA) metabolites and fish oil fatty acids were studied. Sprague-Dawley rats (200–220
g) were fed a fat-free semisynthetic diet supplemented with 10% (by weight) of different combinations of evening primrose
oil (EPO), a rich source of LA and γ-linolenic acid, and polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic
(DHA) acids. The combinations of supplement were as follows: 9% EPO-1% POL, 8% EPO-2% POL, 7% EPO-3% POL, 6% EPO-4% POL and
5% EPO-5% POL. After two weeks on the respective diets, the animals were killed, and the fatty acid compositions of liver
and plasma phospholipids were examined. The results showed that animals fed higher proportions of POL consistently contained
higher levels of dihomo-γ-linolenic acid (DGLA) (p<0.05), a metabolite of LA and GLA, and lower levels of arachidonic acid
(AA) (p<0.01), a metabolite of DGLA through Δ-5-desaturation. Thus, an inverse relationship between AA/DGLA ratio and EPA
levels was found to exist (r=−0.765 in plasma and −0.792 in liver). However, there was no such relationship between AA/DGLA
ratio and DHA levels. This result suggested that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion
of DGLA to AA. 相似文献
13.
The objective of the study was to evaluate potential benefits of docosahexaenoic acid (DHA) rich fish oil supplementation
as an adjunct to statin therapy for hyperlipidaemia. A total of 45 hyperlipidaemic patients on stable statin therapy with
persistent elevation of plasma triglycerides (averaging 2.2 mmol/L) were randomised to take 4 g/day (n = 15) or 8 g/day (n = 15) of tuna oil or olive oil (placebo, n = 15) for 6 months. Plasma lipids, blood pressure and arterial compliance were assessed initially and after 3 and 6 months
in 40 subjects who completed the trial. Plasma triglycerides were reduced 27% by 8 g/day DHA-rich fish oil (P < 0.05) but not by 4 g/day when compared with the placebo and this reduction was achieved by 3 months and was sustained at
6 months. Even though total cholesterol was already well controlled by the statin treatment (mean initial level 4.5 mmol/L),
there was a further dose-dependent reduction with fish oil supplementation (r = −0.344, P < 0.05). The extent of total cholesterol reduction correlated (r = −0.44) with the initial total cholesterol levels (P < 0.005). In the subset with initial plasma cholesterol above 3.8 mmol/L, plasma very low density lipoprotein (VLDL), intermediate-density
lipoprotein (IDL) and low-density lipoprotein (LDL) were isolated and assayed for cholesterol and apolipoprotein B (apoB)
at the commencement of the trial and at 3 months of intervention. Fish oil tended to lower cholesterol and apoB in VLDL and
raise both in LDL. There were no changes in IDL cholesterol, IDL apoB and high-density lipoprotein cholesterol. The results
demonstrate that DHA-rich fish oil supplementation (2.16 g DHA/day) can improve plasma lipids in a dose-dependent manner in
patients taking statins and these changes were achieved by 3 months. Fish oil in addition to statin therapy may be preferable
to drug combinations for the treatment of combined hyperlipidaemia. 相似文献
14.
The effect of a protein diet on the biosynthesis of polyunsaturated fatty acids of the linoleic acid family was studied by
incubation of rat liver microsomes with labeled linoleic acid. The incubation was performed in desaturating, elongating and
desaturating-elongating conditions. In desaturating conditions, linoleic acid was converted to γ-linolenic acid, whereas in
elongating conditions it was converted to 20∶2, 22∶2 and 24∶2. In desaturating-elongating conditions, labeling was found in
γ 18∶3, 20∶2, 20∶3, 20∶4 and 22∶2. A protein diet increased the oxidative desaturation of linoleic acid to γ-linolenic and
arachidonic acid biosynthesis, whereas the elongating reaction was not enhanced in the experimental conditions tested. It
is suggested that the main controllable step in the linoleic acid family is the oxidative desaturation of linoleic acid to
γ-linolenic acid. 相似文献
15.
The effect of glucagon, dibutyryl cyclic adenosine 3′,5′-monophosphate, and epinephrine on the biosynthesis of polyunsaturated
fatty acids of the linoleic acid family was studied. The incubations were performed with rat liver microsomes and labeled
linoleic acid under desaturating and elongating conditions. Under desaturating conditions, linoleic acid was converted to
γ-linolenic acid, whereas under elongating conditions it was converted to 20∶2ω6. Glucagon, dibutyryl cyclic AMP, and epinephrine
decreased the oxidative desaturation of linoleic acid to γ-linolenic acid while the elongating reaction was not modified in
the experimental conditions tested. Consequently, the results support the hypothesis that the oxidative desaturation of linoleic
acid to γ-linolenic acid is the main controllable step in the biosynthesis of polyunsaturated fatty acids of the linoleic
acid family in the microsomes. 相似文献
16.
Leaves from soybean (Glycine max (L.) Merr.) plants were assayed to determine if the relationship between temperature and relative fatty acid composition
observed in the seed oil also existed for the triglycerides in the leaf oil. Leaf samples were harvested from eight soybean
lines (A5, A6, C1640, Century, Maple Arrow, N78-2245, PI 123440 and PI 361088B) grown at 40/30,28/22 and 15/ 12°C day/night.
At 40/30 and 28/22°C, seven fatty acids were observed at a level greater than 1.0%. These included the five major fatty acids
found in the seed oil: palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2) and linolenic (18:3) acid; plus two
fatty acids that had retention times the same as palmitoleic (16:1) and γ-linolenic (18:3 g) acid. In addition, an eighth
fatty acid that had a retention time the same as behenic (22:0) acid was found in the leaves of all lines at 15/12°C. Palmitic,
palmitoleic and stearic acid content did not differ significantly over temperatures. The oleic and linoleic acid content were
each highest at 15/12°C, while the γ-linolenic and the linolenic acid content were each highest at 40/30°C. The fatty acid
composition of the triglyceride portion of the leaf oil did not display the same pattern over temperatures as that observed
for seed oil. 相似文献
17.
This study was designed to examine the effects of dietary n−3 and n−6 polyunsaturated fatty acids (PUFA) on postprandial lipid
levels and fatty acid composition of hepatic membranes. Male Sprague-Dawley rats were trained for a 3−h feeding protocol and
fed one of five semipurified diets: one fat-free diet or one of four diets supplemented with 10% (by weight) each of corn
oil, beef tallow, perilla oil, and fish oil. Two separate experiments were performed, 4-wk long-term and 4-d short-term feeding
models, to compare the effects of feeding periods. Postprandial plasma lipid was affected by dietary fats. Triacylglycerol
(TG) and total cholesterol levels were decreased in rats fed perilla oil and fish oil diets compared with corn oil and beef
tallow diets. Hepatic TG and total cholesterol levels were also reduced by fish oil and perilla oil diets. Fatty acid composition
of hepatic microsomal fraction reflected dietary fatty acids and their metabolic conversion. The major fatty acids of rats
fed the beef tallow diet were palmitic, stearic, and oleic. Similarly, linoleic acid (LA) and arachidonic acid in the corn
oil group, α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) in the perilla oil group, and palmitic acid and docosahexaenoic
acid (DHA) in the fish oil group were detected in high proportions. Both long- and short-term feeding experiments showed similar
results. In addition, microsomal DHA content was negatively correlated with plasma lipid levels. Hepatic lipid levels were
also negatively correlated with EPA and DHA contents. These results suggest that n−3 ALA has more of a hypolipidemic effect
than n−6 LA and that the hypolipidemic effect of n−3 PUFA may be partly related to the increase of EPA and DHA in hepatic
membrane. 相似文献
18.
We investigated the effect of oral supplementation with evening primrose oil, containing 72% linoleic acid (18∶2n−6) and 10%
γ-linolenic acid (18∶3n−6), on the epidermal and neutrophil phospholipid fatty acid composition in 15 patients with atopic
dermatitis (AD). Three different dose levels, 4, 8 and 12 capsules per day containing 0.5 g oil, were given to three groups
of patients. The only n−6 fatty acid showing a significant (p<0.05) dose-related increase was dihomo-γ-linolenic acid (20∶3n−6)
in neutrophil phospholipids. The highest dose increased dihomo-γ-linolenic acid by 45% in neutrophil phospholipids, by 46%
in lesion-free epidermal phosphatidylcholine, and by 15% in lesion-free epidermal phosphatidylethanolamine. In both lesional
and lesion-free epidermis, supplementation resulted in a rise in the ratio between n−6 and monounsaturated fatty acids, reaching
significance (p<0.05) in lesional epidermis. This study shows that moderate and favorable fatty acid changes can be obtained
in the epidermis of AD patients, when given 6 g per day of oil rich in n−6 fatty acids. The abnormal lipid and fatty acid
pattern of the atopic epidermis may be involved in the pathogenesis of the disease, and should therefore be the target for
future therapeutic approaches with fatty acid supplements. 相似文献
19.
P. Hoffmann H. -U. Block J. Beitz Ch. Taube W. Forster P. Wortha P. Singer E. Naumann H. Heine 《Lipids》1986,21(12):733-737
Following the suckling period, four groups of male four-week-old spontaneously hypertensive rats (SHR) were fed semisynthetic
diets with 14% (by weight) of either sunflower seed oil [46% 18∶2(n−6); linoleic acid (LA)-rich], linseed oil [62.5% 18∶3(n−3)+12.9%
18∶2(n−6); α-linolenic acid (LNA)-rich], evening primrose oil [9.2% 18∶3(n−6)+71% 18∶2(n−6); γ-linolenic acid (LNA)-rich]
or hydrogenated palm kernel fat [1.5% 18∶2(n−6); polyunsaturated fatty acid (PUFA)-deficient], respectively, up to an age
of 18 wk. All diets enriched with PUFA provoked an attenuation of hypertension development. The effect was lowest in the LA-rich
group and highest in the γ-LNA-rich group. Differences in fatty acid composition of renal phospholipids between groups reflect
the fatty acids present in the respective dietary fats. Renomedullary production of PGF2α was significantly reduced in α-LNA-rich and slightly diminished in γ-LNA-rich fed rats. Aortic formation of 6-keto-PGF1α and TXB2 was increased in animals fed the γ-LNA-rich diet. Thus, the attenuation of hypertension development cannot be explained only
by changes in prostanoid formation. Other mechanisms possibly involved should be pursued. 相似文献
20.
Fractionation of blackcurrant seed oil 总被引:4,自引:0,他引:4
Blackcurrant seed oil is known to be one of the richest natural sources of γ-linolenic (allcis-6,9,12-octadecatrienoic) acid, with values of up to 20% of this acid. These concentrations are sufficient for most applications
of the oil, but some utilizations require higher concentrations of γ-linolenic acid. Blackcurrant seed oil also contains up
to 14%α-linolenic (allcis-9,12,15-octadecatrienoic) acid. Different fractionation techniques have been evaluated to separate γ-linolenic acid specifically
from the other fatty acids present in the oil and, in particular, fromα-linolenic acid.
Distillation as well as fractionated crystallization at various temperatures did not give any reasonable results. Surprisingly
enough, urea fractionation in methanol gives a specific separation ofα- and γ-linolenic acid, whereas stearidonic (allcis-6,9,12,15-octadecatetraenoic) acid, which is present at around 3% in the blackcurrant seed oil, cannot be separated by urea
fractionation.
Stearidonic acid, like γ-linolenic acid, has a double bond in the Δ6 position, which makes these two acids unique in this
respect. This most probably explains their similar behavior toward urea-occlusion.
Further semi-industrial preparative HPLC separations allowed us to obtain fractions of 95% γ-linolenic acid. 相似文献