Gamma-linolenic Acid Content Research Articles

Tocopherol and fatty acid composition of twenty-five species of Onagraceae Juss.

Chemotaxonomic relationships in Onagraceae have been investigated at the level of leaf and flower compounds but not for seed traits. The objective of this study was to characterize a set of 26 accessions (25 species, 7 genera) of this family for seed oil content, fatty acid composition, tocopherol content and composition, and to evaluate the chemotaxonomic implications of the results. The accessions showed a large variation for all the traits. Gamma-linolenic acid was exclusively found inOenotheraspp. where two groups, showing different concentrations of gamma-linolenic acid and alpha-tocopherol, were observed. The species ofClarkiaPursh were markedly different to the rest of species, showing low alpha-linolenic acid and low gamma-tocopherol concentration.Circaea lutetianaL. had a characteristic tocopherol profile, with high levels (13%) of beta-tocopherol. Variation for fatty acid and tocopherol composition inEpilobiumspp. suggested some phylogenetic relationships. The annual speciesE. paniculatumNutt. showed a characteristic composition very similar to the closely relatedBoisduvalia densiflora(Lindl.) S. Watson. The accessions of the phylogenetically relatedE. fleischeriHochst. andE. dodonaeiVillalso showed similar fatty acid and tocopherol composition. The results of this study suggest a potential chemotaxonomic value of seed fatty acids and tocopherols in Onagraceae.

Tocopherol and fatty acid composition of twenty-five species of Onagraceae Juss.

Chemotaxonomic relationships in Onagraceae have been investigated at the level of leaf and flower compounds but not for seed traits. The objective of this study was to characterize a set of 26 accessions (25 species, 7 genera) of this family for seed oil content, fatty acid composition, tocopherol content and composition, and to evaluate the chemotaxonomic implications of the results. The accessions showed a large variation for all the traits. Gamma-linolenic acid was exclusively found in Oenothera spp. where two groups, showing different concentrations of gamma-linolenic acid and alpha-tocopherol, were observed. The species of Clarkia Pursh were markedly different to the rest of species, showing low alpha-linolenic acid and low gamma-tocopherol concentration. Circaea lutetiana L. had a characteristic tocopherol profile, with high levels (13%) of beta-tocopherol. Variation for fatty acid and tocopherol composition in Epilobium spp. suggested some phylogenetic relationships. The annual species E. pankulatum Nutt. showed a characteristic composition very similar to the closely related Boisduvalia densiflora (Lindl.) S. Watson. The accessions of the phylogenetically related E. fleischeri Hochst. and E. dodonaei Vill., also showed similar fatty acid and tocopherol composition. The results of this study suggest a potential chemotaxonomic value of seed fatty acids and tocopherols in Onagraceae.

Concentration- and time-dependent effects of γ-linolenic acid supplementation to tumor cells in culture

Gamma-linolenic acid (GLA) supplemented to neuroblastoma SK-N-BE, tubal carcinoma TG and colon carcinorna SW-620 cells was incorporated into phospholipids in all the cell lines (although to different extents), in a concentration- and time-dependent manner. All the cell lines were able to metabolize GLA to arachidonic acid, SK-N-BE being the most active. Supplementation with low GLA concentrations for short periods was not sufficient to impair cell proliferation; only higher amounts of GLA had an anti-proliferative effect also in short times. In these conditions, the antiproliferative effect of GLA is probably due to cellular dysfunction caused by fatty acid modifications.

Correlation of glutathione and ascorbate and their dependence on age and season in human lymphocytes: [formula omitted] H. Therriault, A.M. Cantin, T. F,l^p, H. Payette and J.R. Wagner IUGS (d'Youville), 1036 Belvedere Sud, Sherbrooke QuÈbec Canada J1H 4C4

Chemotaxonomic relationships in Onagraceae have been investigated at the level of leaf and flower compounds but not for seed traits. The objective of this study was to characterize a set of 26 accessions (25 species, 7 genera) of this family for seed oil content, fatty acid composition, tocopherol content and composition, and to evaluate the chemotaxonomic implications of the results. The accessions showed a large variation for all the traits. Gamma-linolenic acid was exclusively found inOenotheraspp. where two groups, showing different concentrations of gamma-linolenic acid and alpha-tocopherol, were observed. The species ofClarkiaPursh were markedly different to the rest of species, showing low alpha-linolenic acid and low gamma-tocopherol concentration.Circaea lutetianaL. had a characteristic tocopherol profile, with high levels (13%) of beta-tocopherol. Variation for fatty acid and tocopherol composition inEpilobiumspp. suggested some phylogenetic relationships. The annual speciesE. paniculatumNutt. showed a characteristic composition very similar to the closely relatedBoisduvalia densiflora(Lindl.) S. Watson. The accessions of the phylogenetically relatedE. fleischeriHochst. andE. dodonaeiVillalso showed similar fatty acid and tocopherol composition. The results of this study suggest a potential chemotaxonomic value of seed fatty acids and tocopherols in Onagraceae.

The Comparative Discriminating Abilities of Lipases in Different Media and Their Application in Fatty Acid Enrichment

The generally held belief that the selectivity of lipase can be changed by changing the media from aqueous to non-aqueous was tested by monitoring the rates of hydrolysis, ester synthesis and transesterification with a range of fatty acid mono-esters. Although the absolute rates of reaction varied, hydrolysis was by far the most rapid of the three, the relative rates for the fatty acids used were similar in all three reaction types. The selectivity of the five enzymes used appeared to remain unchanged irrespective of the type of reaction, i.e. hydrolysis of p-nitrophenyl esters, direct ester synthesis with butanol and fatty acid or transesterification with butyl butyrate and fatty acid, and could not be changed by changing water activity. This principle was applied to screen for suitable lipases which could be used to increase the gamma linolenic acid content of a fatty acid mixture. Enzymes could be selected by measuring the rate of hydrolysis of a range of P-nitrophenyl esters.

Biosynthesis of triacylglycerol in the filamentous fungus Mucor circinelloides.

Lipid metabolism was studied in 2-d-old liquid cultures of Mucor circinelloides grown at 25 degrees C. Under these conditions, oil accumulated to 0.5 g l-1 with a gamma-linolenic acid content (gamma 18:3) of 60 mg l-1. The major labelled lipids in cultures incubated with [14C]acetate were triacylglycerol (TAG), phosphatidylcholine (PC) and phosphatidylethanolamine (PE). The proportion of label declined in the phospholipids and increased in TAG with time. [14C]18:1 and [14C]18:2 rapidly appeared in PC and PE and later accumulated in [14C]gamma 18:3. TAG-synthesizing capacity was greatest in the microsomal membrane fraction, which accumulated high levels of phosphatidic acid in the presence of glycerol 3-phosphate and acyl-CoA substrates at pH 7.0. Further metabolism of phosphatidic acid to diacylglycerol and TAG was achieved by increasing the pH to 8.0. Lysophosphatidic acid: acyl-CoA acyltransferase (LPAAT) activity was particularly high and may have accounted for the rapid accumulation of phosphatidic acid in the membranes. The glycerol-3-phosphate: acyl-CoA acyltransferase (GPAAT) and LPAAT were non-specific for a range of saturated and unsaturated species of acyl-CoA although the GPAAT showed a marked selectivity for palmitoyl-CoA and the LPAAT for oleoyl- and linoleoyl-CoA. gamma-Linolenic acid was detected at all three positions of sn-TAG and was particularly enriched at the sn-3 position. The preparation of active in vitro systems (microsomal membranes) capable of the complete biosynthetic pathway for TAG assembly may be valuable in understanding the assembly of oils in future transgenic applications.

Can tumour cell drug resistance be reversed by essential fatty acids and their metabolites?

Tumour cell drug resistance is a major problem in cancer chemotherapy. Essential fatty acids have been shown to be cytotoxic to a variety of tumour cells in vitro. But, the effect of these fatty acids on tumour cell drug resistance has not been well characterized. Gamma-linolenic acid (GLA) of the n-6 series and eicosapentaenoic acid (EPA) of the n-3 series potentiated the cytotoxicity of anti-cancer drugs: vincristine, cis-platinum and doxorubicin on human cervical carcinoma (HeLa) cells in vitro. Alpha-linolenic acid (ALA), GLA, EPA and docosahexaenoic acid (DHA) enhanced the uptake of vincristine by HeLa cells. In addition, DHA, EPA, GLA and DGLA were found to be cytotoxic to both vincristine-sensitive (KB-3-1) and -resistant (KB-Ch R-8-5) human cervical carcinoma cells in vitro. Pre-incubation of vincristine-resistant cells with sub-optimal doses of fatty acids enhanced the cytotoxic action of vincristine. GLA, DGLA, AA, EPA and DHA enhanced the uptake and inhibited the efflux of vincristine and thus, augmented the intracellular concentration of the anti-cancer drug(s). Fatty acid analysis of KB-3-1 and KB-Ch R-8-5 cells showed that the latter contained low amounts of ALA, GLA, 22:5 n-3 and DHA in comparison to the vincristine-sensitive cells. The concentrations of GLA and DHA were increased 10–15 fold in the phospholipid, free fatty acid and ether lipid cellular lipid pools of GLA and DHA treated cells. These results coupled with the observation that various fatty acids can alter the activity of cell membrane bound enzymes such as sodium-potassium-ATPase and 5'-nucleotidase, levels of various anti-oxidants, p53 expression and the concentrations of protein kinase C suggest that essential fatty acids and their metabolites can reverse tumour cell drug-resistance at least in vitro.

Oral administration of unsaturated fatty acids: effects on human peripheral blood T lymphocyte proliferation.

Oils enriched in certain polyunsaturated fatty acids suppress joint pain and swelling in rheumatoid arthritis (RA) patients. Because T lymphocyte activation is important to propagation of joint tissue injury in patients with RA, we examined the effects of fatty acids administered by mouth in vivo on proliferation of human lymphocytes activated through the T cell receptor complex. T cell proliferation was reduced after oral administration of 2.4 g gammalinolenic acid in capsules of borage seed oil. Oral administration of oils enriched in linoleic acid, the parent n-6 fatty acid, and alpha linolenic acid, the parent n-3 fatty acid, did not influence growth of stimulated cells. Fatty acid analyses indicated that suppression of lymphocyte proliferation after gammalinolenic acid administration was associated with increased plasma and peripheral blood mononuclear cell concentrations of gammalinolenic acid and dihomogammalinolenic acid.

Effect of C:N Ratio on Gamma-linolenic Acid Production by Mucor circinelloides Grown on Acetic Acid

Summary The effect of different carbon to nitrogen (C:N) ratios, using acetic acid as carbon substrate, on the growth and production of gamma-linolenic acid (GLA) by Mucor circinelloides CBS 203.28 was examined in fed-batch cultures operated in pH-stat mode with an acetic acid/(NH4)2SO4 solution as titrant. With an increase in the C:N ratio of the feed from 20:1 to 100:1, the final biomass concentration and the percentage of GLA in the neutral lipid fraction decreased. However, the concomitant large increase in the crude oil content of up to 31% of the dry biomass resulted in the intracellular GLA content increasing from a value of 13 to 38.6 mg/g biomass. Increasing the C:N ratio also resulted in an increase in the neutral lipid fraction of the oil with a decrease in the glyco- and phospholipid fractions. The highest GLA concentration of 0.51 g/l culture, a biomass concentration of 23.4 g/l and a GLA content of 22.6% in the neutral lipid fraction was found when using a C:N ratio of 25:1, but with a relatively low GLA content of 21.7 mg/g biomass and a crude oil content of only 11.2%. The respiratory quotient stabilized at a value of about 1.1, suggesting that the glyoxylate shunt was not significantly active relative to the total carbon flux during the lipid accumulation phase.

Enhanced sunflower oil utilization and gamma-linolenic acid production by Mucor circinelloides f.circinelloides CBS 108.16 in the presence of acetate

Mucor circinelloides f. circinelloides CBS 108.16 was grown on 40 g sunflower oil/l and, as expected, produced neutral lipids similar in fatty acyl composition to the original oil. The apparent repression of the Δ 6 fatty acid desaturation was partially reversed when cells were grown on oil (30 g/l) and sodium acetate (10 g/l) as mixed substrates resulting in an increase in gamma-linolenic acid content. Furthermore, a three-fold increase in oil substrate utilization and doubling of biomass production to 19 g/l occurred when sodium acetate was added to the oil substrate.

The effect of acetic acid concentration on the growth and production of gamma-linolenic acid byMucor circinelloides CBS 203.28 in fed-batch culture

The effect of different initial acetic acid concentrations on the growth of and lipid and gamma-linolenic acid (GLA) production byMucor circinelloides CBS 203.28 was determined in a 14 litre stirred tank reactor operated in a fedbatch, pH-stat mode with acetic acid as carbon source and pH titrant. Increased acetic acid concentrations in the culture resulted in a significant increase in the crude oil content of the biomass. By contrast, all the other parameters such as the biomass concentration, GLA and oil yield on acetic acid, the GLA content of the biomass and oil, the growth rate and volumetric rate of GLA production decreased with an increase in acetic acid concentration. The best results were obtained with acetic acid at 2 g/1, which gave 39.8 mg GLA/g biomass and 15.6% GLA in the neutral lipid fraction, amounting to 340 mg GLA/1 culture. A decrease in the glyco- and phospho-lipid fractions during the cultivation coincided with an increase in the neutral lipid fraction. The GLA content of the biomass remained within rather narrow limits of 3.5% to 4% of the biomass, irrespective of the oil content of the biomass. The fatty acid profile was not greatly affected by the acetic acid concentration. The hyphae of the fungus were characterized by the accumulation of large intracellular oil droplets and some septa delimited the hyphae.

The induction of apoptosis in human cervical carcinoma (HeLa) cells by gamma-linolenic acid

A high concentration (50 μg/ml) of gamma-linolenic acid (GLA) induced morphological lesions typical of apoptosis, as well as DNA fragmentation, in HeLa cells. A lower concentration of GLA (20 μg/ml), caused an increased proliferating cell nuclear antigen (PCNA) labelling, with 92.7% cells positive, compared to 27.7% at a concentration of 50 μg/ml GLA. In correlation with these results, the number of cells with degraded DNA below the G 0 G 1 peak increased significantly in the 50 μg/ml GLA-treated cells, but increased only slightly in cells exposed to the lower level of GLA. The high levels of PCNA induced by 20 μg/ml GLA, in both G 1 and S phases, may indicate a state of DNA repair synthesis, whilst at the higher concentration of GLA, most of the cells became apoptotic. Since apoptosis is associated with the deregulation of c-Myc expression, and as the Raf-1-MAP kinase cascade activates the expression of c-Myc and c-Jun, we investigated the effects of 20 and 50 μg/ml GLA on the Raf-1, c-Myc and c-Jun levels, and on the activity of MAP kinase. The results showed that 50 μg/ml GLA lowered the activity of MAP kinase. As expected with the decreased MAP kinase activity in the cells exposed to the higher level GLA, the c-Jun levels were also lowered. The levels of c-Myc, however, were increased. It is therefore possible that the deregulated expression of c-Myc in the HeLa cells exposed to the high level of GLA (50 μg/ml) may contribute to the induction of apoptosis in HeLa cells.

γ-Linolenic Acid Supplementation Can Affect Cancer Cell Proliferation via Modification of Fatty Acid Composition

We examined the effect of gamma-linolenic acid (GLA) supplementation on the growth and fatty acid composition of three human tumor cell lines (the neuroblastoma CHP-212, the tubal carcinoma TG, and the colon carcinoma SW-620), in order to evaluate the relationship between GLA-induced tumor cell death and the distribution of fatty acids in tumor cells. At the highest GLA concentrations (10 and 20 μg/ml), the DNA synthesis was completely abolished; at 5 μg/ml GLA only SW-620 cells did not proliferate, while CHP-212 and TG cells showed a residual [3H]-thymidine incorporation. GLA levels were very low in cells grown in control medium; GLA supplementation caused a significant incorporation of GLA itself in all the cell lines at each concentration. In TG and CHP-212 cells, GLA was metabolized, although to a different extent, to dihomo-gamma linolenic acid and arachidonic acid. SW-620 cells neither elongated nor desaturated the incorporated GLA. The highest cytostatic effect was reached when GLA was not transformed into its metabolites, suggesting that the GLA toxicity to tumor cells is not dependent on metabolites but is due to GLA itself.

The utilization of short-chain monocarboxylic acids as carbon sources for the production of gamma-linolenic acid by Mucor strains in fed-batch culture

The Fischer-Tropsch reaction water, which contains C2 to C5 monocarboxylic acids, generated as a co-product of the Sasol industrial oil-from-coal process, constitutes a potential cheap carbon substrate for the production of gamma-linolenic acid (GLA) by selced Mucor species. Three strains of Mucor were each grown in an air-lift reactor operated in a fed-batch, pH-stat mode under N-limitation with a mixture of C2 to C5 monocarboxylic acids as both pH titrant and carbon source. The production of GLA from this substrate was evaluated. Growth typically resulted in the rapid assimilation of acetic, n-butyric and n-valeric acids. Although propionic, iso-butyric and iso-valeric acids were assimilated to varying degrees, these acids accumulated in the culture. Mucor circinelloides CBS 203.28 gave the best results in that it assimilated 36% to 100% of each acid, had a biomass yield coefficient of 0.3 (calculated on acids utilized), and contained 28% crude oil, 84% of which comprised neutral lipids with a GLA content of 14.4%, giving 33 mg GLA/g biomass. GLA accumulation coincided with a decrease in the stearic-acid content of the neutral-lipid fraction. The results were comparable with previous results obtained with acetic acid and glucose as sole carbon sources, demonstrating the feasibility of producing GLA from the above mixture of organic acids.

Production of gamma-linolenic acid by Mucor circinelloides and Mucor rouxii with acetic acid as carbon substrate

The production of gamma-linolenic acid (GLA) by Mucor circinelloides CBS 203.28 and M. rouxii CBS 416.77 in fed-batch cultures operated in pH-stat mode with acetic acid as carbon substrate and titrant compared favourably with the performance of M. circinelloides in batch culture on glucose. On acetic acid M. circinelloides accumulated up to 39.8 mg GLA/g biomass, with a crude oil content of 28% containing 91% neutral lipids. The GLA content of the neutral lipid fraction was 15.6%.

The Influence of Dissolved Oxygen Tension on the Production of Cocoa Butter Equivalents and Gamma-linolenic Acid by Mucor circinelloides

Summary The influence of different dissolved oxygen tension (DOT) values ranging from 5 to 35% of saturation on the production of cocoa butter equivalents and gamma-linolenic acid by Mucor circinelloides f. circinelloides CBS 108.16 was investigated in nitrogen limited, fed-batch, pH-stat cultures with acetic acid as carbon source. DOT values of 8% and 10% were optimal for crude oil and neutral lipid production. The lipid composition at low and high DOT values differed extensively. The content of gamma-linolenic acid gradually decreased from 12.4% to approximately 4.6% of the neutral lipid fraction when the DOT was decreased from 35% to 5%. The stearic acid (18: 0) content increased from 15.6% of the neutral lipid fatty acids at a DOT of 35% to approximately 27% at a DOT of 5%. Similarly, a dramatic increase in symmetrical triacylglycerols occurred when the DOT was decreased from 35% to 5%. The DOT, therefore, effected major quantitative changes in lipid desaturation and cocoa butter equivalent production, modifying the microbial oil composition also in the DOT range where the respiration rate, and therefore probably growth, was not limited by the level of dissolved oxygen.

In-vitro inhibitory activity of gamma-linolenic acid on Escherichia coli strains and its influence on their susceptibilities to various antimicrobial agents.

Recent experimental evidence implies that polyunsaturated fatty acids (PUFAs) possess anti-infective activity which is unrelated to any alteration of eicosanoid biosynthesis or cytokine production provoked by PUFAs and it seems necessary to establish their possible influence on Gram-negative bacteria. Forty-two Escherichia coli strains were cultured in vitro in the presence of gamma-linolenic acid (GLA) at concentrations of 50 mg/L and 300 mg/L and a total of 77 killing curves were performed with GLA concentrations of 100, 200 and 300 mg/L GLA. At 50 and 300 mg/L, GLA inhibited 9.5% and 33.3% of strains respectively; GLA killing curves demonstrated a > or = 1 log GLA inhibitory effect in 0%, 18.2% and 72.7% of strains after the 5 h sequential exposures at 100, 200 and 300 mg/L GLA but this was not observed after the 24 h GLA exposure. Following removal of the E. coli strains from the culture medium with GLA, > or = four-fold increases in MICs and/or MBCs of various antimicrobials, were observed in 42.9% and 60% of strains after exposure to 50 and 300 mg/L GLA respectively; most of these increases involved aminoglycosides. The reproducibility of GLA inhibitory effects and increase in MICs and/or MBCs for E. coli in the two different experimental procedures used, was 82% and 73% respectively. Further studies are necessary to clarify the mechanism of GLA action on E. coli and assess the clinical relevance of these findings.

Mucor—a source of cocoa butter and gamma-linolenic acid

Lipid analyses were performed on 28 strains of various species of the genus Mucor. In shake flasks with glucose as carbon source, the gamma-linolenic acid (GLA) content in the neutral lipid (NL) fraction of some Mucor species was up to 38 mg GLA/g dry biomass. Some Mucor species produced more than 20% (w/w) stearic acid (18:0) and more than 60% of their NL content as symmetrical triacylglycerols (SUS-TAGs) which corresponded to those of cocoa butter. Three Mucor species were evaluated in terms of the production of SUS-TAGs and GLA in pH-stat, fed-batch cultures in an air-lift fermenter with acetic acid as titrant and carbon source. Mucor circinelloides f. circinelloides CBS 108.16 accumulated 27% 18:0 in the NL fraction, which constituted approximately 40% of the dry biomass. In this case, the NL fraction contained more than 70% (w/w) SUS-TAGs.

Fatty acid production characteristics of fungi with particular emphasis on gamma linolenic acid production

The fatty acid production characteristics of fungi are described. These characteristics are the relationship between the oil content of the cell and the fatty acid content of the oil. For example, for polyunsaturated fatty acid (PUFA) production by Mucor hiemalis IPD 51, the oil content of the cell and the GLA content of the oil are coupled. For fungal production of some PUFA, synthesized after the rate-limiting step in the fatty acid anabolic chain, a maximum fatty acid production model was developed to link the fatty acid content of the oil and the oil content of the cell. Maximum volumetric productivity of gamma linolenic acid (GLA) by molds was found to occur at a specific GLA content of the oil. For example, for M. hiemalis IPD 51, a maximum volumetric of 4.7 mg GLA/L . h was produced at a GLA content of the oil of 8% to 10%. Similarly for Mucor circinelloides v. Tieghem IPD 155 a maximum volumetric productivity of 4.8 mg GLA/L . h was produced at a GLA content of the oil of 14% to 16%. These results imply that, when screening microorganisms for GLA or other fatty acid production, a number of medium compositions need to be evaluated to determine the tradeoff between oil content of the cell and fatty acid content of the oil.

Clinical tolerance and metabolism of a fat emulsion containing carnitine and gamma-linolenic acid

The purpose of the present study was to study the metabolism and evaluate the tolerance of a new fat emulsion, which is rich in gamma-linolenic acid and has been supplemented with carnitine. 24 adult male volunteers participated in an open, randomised, crossover study where half of the subjects were given Intralipid 20% (IL) on day one followed by administration of the supplemented fat emulsion (FE) on day two, the other half being treated in the reverse order. Both fat emulsions were first administered as a bolus dose of 0.10 g triglycerides per kg BW (an intravenous fat tolerance test) followed 40 min later by a continuous intravenous infusion during 4 h at a rate of 0.21 g triglycerides per min. The plasma fractional elimination rate, k 2-value, was lower for FE than for IL (4.6 ± 1.8 vs 5.3 ± 1.6% per min, P < 0.05, mean ± SD). Infusion of FE, as distinct from IL administration, was accompanied by a marked increase in serum gamma-linolenic acid concentration (239 ± 133 vs 0 ± 11 μmol/l, P < 0.05). No differences between FE and IL were discernible regarding the serum concentrations of dihomo-gamma linolenic acid (C 20: 3ω6), arachidonic acid (C 20: 4ω6), adrenic acid (C 22: 4ω6) or docosapentanaenoic acid (C 22: 5ω6). Leucocyte chemotaxis and random migration increased, 0.5 ± 0.3 arb. units (P < 0.01) and 0.2 ± 0.2 arb. units (P < 0.05), during infusion of FE but no such effect was noted during IL administration. No effect of the fat emulsion composition and carnitine was detected on phagocytosis and oxidative metabolism of neutrophil leucocytes. In conclusion, the new fat emulsion containing a relatively high proportion of gammalinolenic acid and supplemented with carnitine was found to be well tolerated although it was eliminated from plasma at a 13% slower rate. The supplemented fat emulsion had a moderate stimulatory effect on leukocyte chemotaxis.