Blackcurrant Seed Oil Research Articles

Dietary Lipids and 5′-Nucleotidase Activity of Rat Cell Plasma Membranes

Three groups of adult rats were fed black currant or olive oils or a 1:1 mixture of the two for three months. Feeding black currant oil diets, high in 18:2 (n-6), 18:3 (n-6), 18:3 (n-3), increased the heart and liver plasma membrane content of linoleic and arachidonic acid with a concomitant decrease of oleic acid. PUFA, n-3 and n-6 content and the bilayer lipid fluidity as examined by measuring the fluorescence anisotropy of diphenylhexatriene were not significantly affected. On the contrary, the 5′-nucleotidase of liver membrane of rats fed black currant diets was lower than that observed in membranes of liver from olive oil fed rats. Therefore it is concluded that PUFA and n-3/n-6 ratio as well as membrane fluidity do not influence the 5′-nucleotidase activity. It is suggested that the activity is sensitive to the amount of a specific fatty acid of the membrane (i.e., oleic or arachidonic acid) and/or to lipid supplementation which can influence the eicosanoids metabolism.

Abnormal polyunsaturated lipid metabolism in the obese Zucker rat, with partial metabolic correction by γ-linolenic acid administration

Below-normal proportions of phospholipid (PL) arachidonic acid (20:4ω6) have been reported in serum from obese humans and in liver from obese Zucker rats. This implies an abnormality of 20:4ω6 formation from linoleic acid (18:2ω6), possibly in the Δ6 desaturase step, or alternatively an abnormality in the catabolism or distribution of arachidonate. We previously speculated that a reduced proportion of 20:4ω6 in hepatic PL could contribute to the etiology of genetic obesity. Providing 18:3ω6 would bypass Δ6 desaturase and possibly normalize hepatic PL 20:4ω6. Therefore weanling Zucker rats were given free access to a defined diet (11% of energy as soy oil) and gavaged daily with 100 μL of either black currant oil concentrate ([BCO] 8% 18:2ω6 and 70% 18:3ω6) or soy oil ([Soy] 55% 18:2ω6 and <0.1% 18:3ω6). Groups of eight lean and eight obese animals were randomized to receive Soy or BCO in a 2 × 2 design; 10 obese and 10 lean rats were fed a stock diet (nongavaged reference). All groups of lean rats had identical weight gain; food intake for Soy lean and BCO lean did not differ. The obese reference animals and Soy obese animals did not differ in weight gain. However, BCO obese animals ate less food ( P < .06), gained less weight ( P < .0001), and had lower percent body fat ( P < .05) compared with the Soy obese animals. The fatty acid constituents from serum, liver, and adipose tissue showed marked differences between lean and obese animals. Hepatic PL 20:4ω6 was lower in Soy obese than in lean ( P < .002), but was normalized by BCO gavage (diet effect, P < .007). The paucity of hepatic PL 20:4ω6 was not due to reduced desaturase activity, as the proportions of other desaturase products (20:3ω6, 20:3ω9, 20:5ω3) were significantly elevated in Soy obese rat liver and serum. Serum and hepatic cholesteryl ester 20:4ω6 levels were elevated in obese versus lean rats ( P < .02 and P < .0001), indicating abnormal arachidonate distribution in the obese Zucker rat. Because BCO selectively reduced weight gain and percent body fat in obese Zucker rats, our results imply a role for abnormal ω6 fatty acid metabolism in the etiology of Zucker obesity. However, due to the potential risks of enhancing tissue 20:4ω6, great caution is advised in extrapolating our results with BCO to the treatment of obesity in humans.

Plant and marine n-3 fatty acids inhibit experimental metastasis of rat mammary adenocarcinoma cells

The effectiveness of dietary n-3 plant and marine fatty acids and n-6 gamma-linolenic acid (GLA) was tested as an antimetastatic modality in the experimental model of metastasis of 13762MAT:B mammary adenocarcinoma cells. Weanling female Fischer 344 rats were placed on one of the following diets: I—23.52% blackcurrant oil (BCO), II—23.52% corn oil (CO), III—15.52% BCO + 8% fish oil (FO), IV—20.52% FO + 3% CO, and V—5% CO. After 8 weeks, 15 rats per group were injected i.v. with 10 5 cells and diets were continued until sacrifice. In the 23.52% CO group (II), the number of small (<2 mm) and large (>2 mm) lung metastatic foci and their total volume were significantly greater than the BCO- and/or FO-fed groups (I, II and IV). Although the number of small metastatic foci was comparable in the 5% and 23.52% CO groups, the number of large foci and the total tumor volume were reduced in the 5% CO group. These results suggest that, compared to a low-corn oil diet or a high-fat diet containing a mixture of marine and plant n-3 fatty acids plus n-6 GLA, a 23.52% corn oil diet can enhance experimental metastasis of mammary adenocarcinoma cells. Total number of metastatic foci and tumor volume were the smallest in group III, receiving a combination of plant and marine n-3 fatty acids.

Cytokine and prostaglandin production by monocytes of volunteers and rheumatoid arthritis patients treated with dietary supplements of blackcurrant seed oil.

In this study, dietary supplements of blackcurrant seed oil (BCO) rich in the n-6 polyunsaturated fatty acid (PUFA) gamma-linolenic acid were fed to both RA patients and healthy volunteers with sunflower seed oil being fed to control subjects. A significant improvement in morning stiffness was noted in the RA patients receiving BCO. Monocytes were isolated from all subjects and cultured in the presence of lipopolysaccharide. It was observed that the production from the cultured monocytes of the cytokines IL-1 beta, TNF alpha and IL-6 as well as the prostaglandin PGE2 was markedly altered in those subjects given BCO. The results suggest that the numerous beneficial effects of PUFAs in inflammatory diseases such as RA may be due to a reduction in the secretion of the inflammatory cytokines IL-1 beta and TNF-alpha via redirection of eicosanoid metabolism although the possibility cannot be excluded that the PUFAs may be altering cytokine release directly through an effect on monocyte membranes.

Dose-response effects of dietary γ-linolenic acid—enriched oils on human polymorphonuclear-neutrophil biosynthesis of leukotriene B4

The dose-dependent effect of dietary supplemented gamma-linolenic acid (GLA, 18:3n-6)-enriched borage oil (Bor) and black-currant oil on the ability of calcium ionophore-activated human polymorphonuclear neutrophils (PMN) to generate leukotriene B4 (LTB4) was investigated in adult healthy human volunteers. Significant (P less than 0.05) elevation of dihomo-gamma-linolenic acid (DGLA, 20:3n-6), an elongation product of GLA, was revealed in PMN phospholipids after ingestion of either 0.48 or 1.5 g GLA-enriched oil/d. This elevation of DGLA in the PMN phospholipids paralleled the decreased capacity of calcium ionophore-activated PMN to generate LTB4. Although the inhibition of LTB4 was greater with the ingestion of 1.5 g GLA-enriched BOR/d, it was not significantly different from the ingestion of 0.48 g/d. Taken together, dietary ingestion of GLA-fortified oils does modulate PMN generation of proinflammatory LTB4.

Determination of plant triacylglycerols using capillary gas chromatography, high-performance liquid chromatography and mass spectrometry

Molecular species of triglycerides (TG) were determined in plant fats and oils, both qualitatively and quantitatively, by means of capillary gas chromatography (CGC) on a “polarizable” column, reversed-phase C 18 high-performance liquid chromatography (RP-HPLC) and desorption chemical ionization mass spectrometry (DCI-MS). For the qualitative analysis values of the equivalent carbon number (ECN) and equivalent chain length (ECL) were used for the identification of individual molecular species of TG by means of RP-HPLC or CGC. Plant oils including cocoa butter with smaller numbers of double bonds can be determined without any problems by means of CGC, RP-HPLC and DCI-MS. The determination by CGC and partially also RP-HPLC failed only with oils with either a complex distribution of chain lengths, i.e., rape seed oil (high erucic acid) or a high unsaturation index (linseed oil and blackcurrant oil). However, with complementary results from all three methods it was possible to identify numerous molecular species of triglycerides in various plant oils.

Eicosanoid synthesis and ornithine decarboxylase activity in mammary tumors of rats fed varying levels and types of n-3 and/or n-6 fatty acids

Virgin female Sprague-Dawley rats (50 days of age) were administered a single intragastric 10 mg dose of 7,12-dimethylbenz(a) anthracene (DMBA). Three weeks later they were placed on diets containing either 20% corn oil (CO), 20% primrose oil (PO), 20% black currant seed oil (BCO), 20% borage oil (BO), 15% menhaden oil plus 5% corn oil (15% MO + 5% CO), 10% menhaden oil plus 10% corn oil (10% MO + 10% CO), 5% menhaden oil plus 15% corn oil (5% MO + 15% CO) or 10% menhaden oil plus 10% borage oil (10% MO + 10% BO). Incidences of mammary tumors at 16 weeks post-DMBA were 80% in rats fed the CO diet, 84% in rats fed PO diet, 67% in rats fed BCO diet, 88% in rats fed BO diet, 60% in rats fed 15% MO + 5% CO diet, 67% in rats fed 10% MO + 10% CO diet, 83% in rats fed 5% MO + 15% CO diet, and 92% in rats fed 10% MO + 10% BO diet. Tumor multiplicity was lowest in PO-fed rats and highest in BO-fed rats. The tumor burden per tumor-bearing rat was lowest in rats fed the 15% MO + 5% CO, and 10% MO + 10% CO, diets and highest in those fed 20% BCO diet. Although body weight at 16 weeks post DMBA was not significantly different among the dietary groups, food intake was significantly greater in rats fed a diet containing 20% BO, or 5% MO + 15% CO. Prostaglandin (PGE) and leukotrienes (LTB 4 and LTC 4) syntheses, ODC activity and mammary tumorigenesis were significantly inhibited by the diet containing 15% MO + 5% CO. Gamma-linolenic acid (GLA, 18:3 n-6)-containing diets (PO, BO and BCO) significantly increased PGE 1 synthesis but did not inhibit mammary tumorigenesis except for the 20% BCO diet that contains alpha-linolenic acid (ALA 18:3, n-3). This suggests that simultaneous inhibition of eicosanoid synthesis and ODC activity are necessary to inhibit mammary tumorigenic response (as seen in the 15% MO + 5% CO group) in DMBA-induced mammary tumor model in rats.

The response to endotoxin in guinea pigs after intravenous black currant seed oil

The influence on the metabolic response to endotoxin of three days of total parenteral nutrition with lipids high in gammalinolenic acid (18:3 omega 6, GLA) compared to soy oil (SO) was examined in acute operatively stressed guinea pigs. GLA is the precursor of dihomogammalinolenic acid (DHLA), the substrate for synthesis of "1" series prostaglandins such as PGE1, which have previously been shown to be protective in endotoxin lung injury and traumatic shock. Guinea pigs fed an intravenous diet containing black currant seed oil (BCO) emulsion (20% GLA) or soy oil emulsion (0% GLA) for 2.5 days had their arterial pH, pCO2, pO2, and bicarbonate measured at baseline and hourly during a 7-hr infusion of endotoxin (lipopolysaccharide (LPS), 2mg/kg) or saline. Plasma lactate and fatty acid profile analyses were performed at the end of the LPS infusion. Increased levels of GLA and DHLA were present in the plasma phospholipid fraction of animals fed the black currant seed oil diet, while soy-fed animals had only trace amounts of GLA. In addition, the ratio of DHLA to arachidonate was higher in animals receiving the black currant seed oil total parenteral nutrition (TPN). After 2 hr of LPS infusion, all animals exhibited the typical shock response resulting in metabolic acidosis characterized by a significant (p less than 0.05) drop in pH from 7.34 +/- .02 (SO) and 7.39 +/- .02 (BCO) at baseline to 7.14 +/- .05 and 7.22 +/- .04 by 7 hr for SO and BCO groups, respectively. Plasma lactate values at the end of the infusion were significantly elevated compared to saline in both groups (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of Dietary Blackcurrant Seed Oil on Mouse Macrophage Subclasses of Choline and Ethanolamine Glycerophospholipids

There have been reports that dietary gamma-linolenic acid [18:3(n-6)] and alpha-linolenic acid [18:3(n-3)] are capable of regulating cellular eicosanoid biosynthesis and inflammation. Because the eicosanoid cascade is regulated in part by the distribution of arachidonic acid [20:4(n-6)] among phospholipid subclasses, the effects of feeding blackcurrant seed oil [containing 18:3(n-6) and 18:3(n-3)] on the fatty acid composition of diacyl, alkylacyl and alkenylacyl subclasses of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were studied in mouse peritoneal macrophages. After 4 wk of dietary treatment, the relative distribution (mol %) of macrophage phospholipid classes and subclasses was not altered in animals fed blackcurrant seed oil relative to those fed corn oil [containing linoleic acid, 18:2(n-6)]. Macrophages from blackcurrant seed oil-fed animals had reduced levels of PC diacyl 18:3(n-6), 18:3(n-3), 20:3(n-6), 22:5(n-3), and alkylacyl 20:3(n-6), 22:5(n-3) and 22:6(n-3). In general, dietary blackcurrant treatment produced fatty acid alterations in PE subclasses that were similar to those in PC. A major exception, however, was the reduction in 20:4(n-6) levels in all PE subclasses, whereas no effect in PC subclass 20:4(n-6) levels was noted. These findings indicate i) that pronounced differences in the polyunsaturated fatty acid (PUFA) compositions of macrophage PC and PE subclasses exist following dietary fat manipulation and ii) that 18:3(n-6) and 18:3(n-3) feeding can increase potential anti-flammatory precursor levels of 20:3(n-6) and (n-3) PUFA in the macrophage.

Triacylglycerol structure of plant and fungal oils containing ψ-linolenic acid.

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.

Characterization of gamma-linolenic acid in Ribes seed.

The total lipid content of fruit seeds of the Ribes family ranges by weight from 18.3% in goose-berries (Ribes uva crispa) to 30.5% in black currants (Ribes nigrum). Isolation procedures and analytical methods (gas chromatography, mass spectrometry, high performance thin layer chromatography and stereospecific analysis) demonstrate that the oils from Ribes seeds contain up to 19% by weight of gamma-linolenic acid (gamma-LA, C18:3, n-6) in black currant oil. This last Ribes species thus constitutes one of the richest natural sources in gamma-LA yet described. These oils appear promising for critically ill patients who seem unable to convert linoleic acid into subsequent EFA fractions.