Linoleic Acid Isomers Research Articles

Endogenous synthesis of milk cis-9,trans-11 conjugated linoleic acid in dairy ewes: Quantification using 13C-labeled vaccenic acid and comparison with estimates based on cobalt administration

Isotopic tracers are used to directly quantify the effect of mammary Δ9-desaturation on milk fatty acid (FA) composition, but very few studies have applied this method to measuring the endogenous synthesis of rumenic acid (RA; cis-9,trans-11 conjugated linoleic acid) in cows and goats, and no publications exist in ewes. In sheep, knowledge about the contribution of stearoyl-coenzyme A desaturase (SCD) to milk FA secretion is derived mostly from indirect estimates based on inhibition of the enzyme by oral administration of cobalt, a cost-effective method that has not been validated to date. To fill both gaps, we conducted an isotopic tracer assay in sheep to quantify the proportion of endogenous RA in milk for the first time in this species. We then compared the results with estimates derived from a Co administration assay performed on the same animals. First, 5 lactating ewes received an intravenous injection of 200 mg of [1-13C]trans-11 18:1 (vaccenic acid, VA), the precursor for RA production by SCD activity. At -24, -15, 0, 9, 24, 33, 48, 57, 72, 81, and 96 h post-injection, we recorded milk yield and collected milk samples to examine fat concentration and FA profile. We conducted compound-specific isotope analysis of VA and RA by gas chromatography-combustion isotope ratio mass spectrometry. Afterward, in the Co administration assay, ewes received a daily dose of 7 mg of Co/kg of body weight for 5 d. We analyzed milk samples for composition before and on the last days of cobalt dosing. On average, 17% of the injected amount of [1-13C]VA was transferred to milk within 96 h post-injection, and up to 29% of the VA taken up by the mammary gland was desaturated to milk RA. Under our conditions, the mean proportion of this conjugated linoleic acid isomer deriving from Δ9-desaturation represented 82 to 90% of the amount secreted in milk. However, the proportion estimated in the Co assay with calculations based on individual FA concentrations was lower (on average, 46%). When we calculated the same estimates based on changes in Δ9-desaturation ratios after Co dosing, the higher values of endogenous RA (75%) did not differ from the results of the isotopic tracer assay. Nevertheless, correlation analysis between the results obtained through [1-13C]VA or Co administration revealed no significant relationship, which would prevent acceptance of the latter as a reliable alternative to isotopic labeling to examine mammary Δ9-desaturation in dairy ewes.

Effect of Nutrition on flaxseed Supplementation to Lactating Goats on Physiochemical and Nutritional Properties of Domiati Cheese in Halayeb, Shalateen and Abu Ramad Triangle of Egypt

The purpose of this research was to evaluate the effect of feeding lactating goats with flaxseed on the physicochemical, sensory properties, yield, texture and fatty acids profile of Domiati cheese. Goat's milk resulted from goat feed different flaxseed levels (0, 7 and 14%) were used in the preparation of goat's Domiati cheese which was stored at 4±1oC for 60 days. Results showed that supplementing flaxseed at level 7and 14% had significantly (P< 0.05) increased cheese protein, total solids and lactose, while no effect was observed on cheese fat. Cheese yield was significantly increased (P< 0.5) for cheese supplemented with 7 and 14%flaxseed than control cheese. Results also, showed in significant differences (P<0.05) on short- (SCFA) and medium-chain fatty acids (MCFA) .While a significant increase of mono -unsaturated (MUFA) and poly-unsaturated fatty acids (PUFA) in cheese fat were observed. Moreover, concentrations of conjugated linoleic acid (CLA) isomers and linolenic acid (C18:3) in cheese fat were increased linearly (P < 0.05) with the increase of flaxseed level. The concentration of CLA and C18:3 in cheese with7 and 14 % flaxseed concentrates significant (P< 0.05) increased. It was concluded that feeding flaxseed to lactating goats improved fatty acids profile in cheese as well as cheese yield. The texture profile parameters were significant (P< 0.05) decreased. Sensory properties scores were increased during storage period. Generally, resultant goat's Domiati cheese supplemented with 7 and 14% flaxseed were considered highly acceptable and it has many health benefits than the control cheese.

Diverse inhibition of forkhead box O1 activity by linoleic acid isomers - potential role in lipid metabolism in HepG2 cells and livers of C57BL/6J mice.

Conjugated dienes of linoleic acid (CLA) are constitutional and geometric isomers of linoleic acid that are commonly used as dietary supplements during body mass reduction. Their role in the reduction of lipid deposits in liver tissue is not unequivocal. CLA contain an equimolar mixture of two isomers of linoleic acid: trans-10,cis-12 CLA and cis-9,trans-11. Only one isomer - trans-10,cis-12 CLA exhibits fat-reducing properties, cis-9,trans-11 CLA does not. The main goal of this study was to determine if CLA isomers affect the activation of forkhead box O1 (FoxO1) in liver cells and tissue. FoxO1 is a protein that plays a crucial role in regulation of lipid and carbohydrates metabolism. In vitro and in vivo models of our study were HepG2 cells and C57BL/6J mice. Methods used in the study were qPCR - quantification of FoxO1 gene expression, Western blot - posttranslational phosphorylation of FoxO1, Oil Red O (ORO) - lipid staining and ELISA - quantification of apoB100. In both models trans-10,cis-12 CLA diminished FoxO1 gene expression: decrease by 44.1 ± 20.9% SD in the cells and 65.4 ± 29.8% SD in mice. The lowest accumulation of lipids (drop of 37.2 ± 1.7% SD) and the highest increase of apoB100 protein (74 ± 12.8% SD) were detected in the medium of cells cultured with trans-10,cis-12 CLA. Both isomers of linoleic acid have different effects on lipid metabolism. Isomer c9,t11 CLA accelerates lipogenesis, whereas isomer t10,c12 CLA activates secretion of lipids in HepG2 cells. In contrast to the in vitro study, unfortunately this pro-health property of t10,c12 CLA was not confirmed in the in vivo model. This casts a shadow on CLA dietary supplements that are commonly used among people with type 2 diabetes, NAFLD (non-alcoholic liver disease) or a metabolic syndrome in order to lose weight.

Conjugated Linoleic Acid Isomers Affect Profile of Lipid Compounds and Intensity of Their Oxidation in Heart of Rats with Chemically-Induced Mammary Tumors-Preliminary Study.

Breast cancer and cardiovascular diseases (CVD) have shared risk factors and mechanisms of pathogenicity, as proven by increased cardiac risk in breast cancer patients receiving anticancerogenic therapies and in cancer survivors. A growing mammary tumor may cause heart injury in cancer patients who have not yet been treated. This study aimed to evaluate the effect of conjugated linoleic acid (CLA) supplementation of female rats with 7,12-dimethylbenz(a)anthracene (DMBA)-induced cancerogenesis on fatty acids (FAs), conjugated FAs (CFAs), malondialdehyde (MDA), cholesterol and oxysterols content in cardiac tissue. FAs, cholesterol and oxysterols contents were determined by gas chromatography coupled with mass spectrometry, while the contents of CFAs and MDA were determined by high performance liquid chromatography with photodiode detection. Our results indicate that both CLA supplementation and the presence of tumors influence the lipid biomarkers of CVD. A significant interaction of both experimental factors was observed in the content of polyunsaturated FAs (PUFAs), n-6 PUFAs and CFAs. CLA supplementation significantly inhibited PUFA oxidation, as evidenced by the lower content of MDA in rats’ hearts, while the cancerous process intensified the oxidation of cholesterol, as confirmed by the elevated levels of 7-ketocholesterol in DMBA-treated rats. These results may significantly expand knowledge about CLA properties in terms of the prevention of co-existing non-communicable diseases.

Conjugated linoleic acid improves glucose and lipid metabolism in diabetic mice

To analyze the effect of conjugated linoleic acid (CLA) on glucose and lipid metabolism in obese diabetic (db/db) mice. db/db mice were randomized for treatment with saline or CLA mixture administered intragastrically. The changes in body weight, dietary intake, water intake, oral glucose tolerance, triglyceride and total cholesterol were recorded after the treatments. HE staining and oil red O staining were used to assess liver pathologies and fatty acid content. The expression levels of PPARα, PPARγ, CD36, CHREBP and SREBP-1c were detected using real-time PCR and Western blotting. HepG2 cells were treated with CLA and linoleic acid and the expressions of PPARα, ACC, P-ACC, and CD36 were detected; the level of acetyl-CoA in the cell supernatant was detected using ELISA. CLA treatment obviously reduced the dietary and water intake of db/db mice, effectively reduced the body weight and decreased serum triglyceride and cholesterol levels (P &lt; 0.05). CLA significantly reduced fasting blood glucose, increased glucose tolerance, reduced the accumulation of lipid droplets in the liver and improved lipid metabolism in db/db mice. The mice showed significantly increased expression of PPARα (P &lt; 0.05) and lowered CD36 expression (P &lt; 0.001) in the liver after CLA treatment. Cellular experiments showed that CLA significantly up-regulated PPARα (P &lt; 0.001) and P-ACC and decreased the expression of CD36 (P &lt; 0.01). ELISA showed that acetyl-CoA was significantly up-regulated in the cells after CLA treatment (P &lt; 0.01). The mixture of two conjugated linoleic acid isomers can reduce fasting blood glucose, increase glucose tolerance and improve glycolipid metabolism in db/db mice by enhancing the expression of PPARα, increasing P-ACC and inhibiting CD36 expression.

GTRS and 2D-NMR studies of alpha and gamma linolenic acids each containing the same H2C14-(H–C[dbnd]C–H)–C11H2–(H–C[dbnd]C–H)–C8H2 moiety

• C14H2 -(H–C13 = C12–H)– C11H2 -(H–C10 = C9–H)– C8H2 is exactly the same structure in both Linolenic Acid isomers. • In γ-LN, chemical shifts for sites C14H2 and C8H2 are the same (1H = 2.65 ppm; 13C = 24.9 ppm). • In α-LN, 1H chemical shifts for sites C14H2 and C8H2 are the same (2.65 ppm) whereas the 13C chemical shifts are discretely different (24.9 ppm versus 24.7 ppm). • Chemical shifts for C11H2 are similar and unequal (1H = 0.78 ppm, 13C = 13.3 ppm α-LN; 1H = 0.72 ppm 13C = 13.5 ppm γ-LN). • Chemical shifts for C2H2 are similar and unequal (1H = 2.12 ppm, 13C = 33.4 ppm α-LN; 1H = 2.11 ppm 13C = 33.2 ppm γ-LN). • Moiety C17H2-(H–C16 = C15–H) is molecular site among redundant structures in α-LN at which spectroscopic differences are the most different and most important.

Antioxidant activity and lipid oxidation in milk from cows with soybean oil and propolis extract added to their feed

Abstract The presence of PUFA (polyunsaturated fatty acids) in cow milk, including conjugated linoleic acids (CLA) isomers, makes milk susceptible to lipid oxidation, and may lead to the formation of volatile products responsible for a rancid smell. Consequently, including natural antioxidants in the diet of dairy cattle can assist in preventing lipid oxidation. In this study, soybean oil (a source of PUFA) and different ethanolic extracts of Brazilian propolis were included in the cows' feed, and the antioxidant activity and lipid oxidation of the animals' milk was assessed. Antioxidant activity was analyzed using the DPPH method, potassium ferricyanide reduction and chelating ability. Total phenolic compounds and flavonoids were also determined. Lipid oxidation was assessed by determining conjugated dienes and the production of aldehydes (propanal, pentanal, hexanal and octanal). Increased antioxidant activity was seen in the samples of milk from cows receiving propolis. Similarly, the addition of ethanolic extract of propolis to the diet of dairy cattle increased milk protection for two treatments with propolis against lipid oxidation in terms of production of propanal and hexanal. These results confirm the positive effect of applying this natural additive to the diet of lactating cows, improving the nutritional quality of the milk produced.

Modulating Heterologous Pathways and Optimizing Culture Conditions for Biosynthesis of trans-10, cis-12 Conjugated Linoleic Acid in Yarrowia lipolytica.

A novel recombinant strain has been constructed for converting glycerol into a specific conjugated linoleic acid isomer (trans-10, cis-12 CLA) using Yarrowia lipolytica as host. The lipid accumulation pathway was modified for increasing lipid content. Overexpression of the diacylglycerol transferase (DGA1) gene improved the intracellular lipid yield by approximately 45% as compared to the original strain. The corresponding intracellular lipid yield of recombinant strain WXYL037 reached 52.2% of the cell dry weight. In combination with integration of Δ12 desaturase from Mortierella alpina (MA12D) and DGA1, the linoleic acid (LA) production content reached 0.88 g/L, which was 2-fold that of the original strain. Furthermore, with overexpressed DGA1, MA12D and Propionibacterium acnes isomerase (PAI), the titer of trans-10, cis-12 CLA in WXYL037 reached 110.6 mg/L after 72 h of shake flask culture, representing a 201.8% improvement when compared with that attained in the WXYL030 strain, which manifested overexpressed PAI. With optimal medium, the maximum CLA content and lipid yield of Y. lipolytica Po1g were 132.6 mg/L and 2.58 g/L, respectively. This is the first report of the production of trans-10, cis-12 CLA by the oleaginous yeast Y. lipolytica using glycerol as the sole carbon source through expression of DGA1 combined with MA12D and PAI.

Decreased All- trans Retinoic Acid-Induced Expression of Sodium-Iodide Transporter in Mammary Epithelial Cells Caused by Conjugated Linoleic Acid Isomers.

Expression of sodium-iodide symporter (NIS) is stimulated by sterol-regulatory-element-binding transcription factors (SREBFs) in mammary epithelial MCF-7 cells. Because conjugated linoleic acid (CLA) isomers have been shown to inhibit transcriptional activity of SREBFs in the mammary gland, the hypothesis was tested that CLA isomers inhibit NIS expression induced by all- trans retinoic acid (ATRA) in MCF-7 cells through inhibiting SREBF activity. c9t11-CLA and t10c12-CLA decreased ATRA-induced NIS-mRNA expression from 1.00 (ATRA alone) to 0.80 ± 0.12 (200 μM c9t11-CLA, P < 0.05) and 0.62 ± 0.10 (200 μM t10c12-CLA, P < 0.05), NIS-protein expression from 1.00 (ATRA alone) to 0.77 ± 0.08 (200 μM c9t11-CLA, P < 0.05) and 0.63 ± 0.05 (200 μM t10c12-CLA, P < 0.05), and NIS-promoter activity from 1.00 (ATRA alone) to 0.74 ± 0.13 (200 μM c9t11-CLA, P < 0.05) and 0.76 ± 0.13 (200 μM t10c12-CLA, P < 0.05); however, c9t11-CLA and t10c12-CLA increased the mRNA levels of SREBF isoforms and their target genes. In contrast, the mRNA expression of peroxisome-proliferator-activated receptor γ (PPARG) was strongly induced by ATRA alone but decreased by CLA isomers from 1.00 (ATRA alone) to 0.80 ± 0.06 (200 μM c9t11-CLA, P < 0.05) and 0.86 ± 0.06 (200 μM t10c12-CLA, P < 0.05). Overexpression of PPARγ in MCF-7 cells increased basal NIS-promoter activity, and treatment with the PPARγ ligand troglitazone stimulated ATRA-induced NIS-promoter activity. In conclusion, the results suggest that CLA isomers exert their effect on the expression of NIS by decreasing PPARG expression in MCF-7 cells.

Punica granatum (Pomegranate) Seed Oil and Momordica charantia (Bitter Melon) Extract Affect the Lipid's Profile and Oxidative Stability of Femoral Muscles of Rats

Pomegranate seed oil (PSO) and bitter melon extract (BM), used in folk medicine nowadays are available as dietary supplements, but information about consequences of their simultaneous usage are still scarce. This study aims to evaluate the influence of supplementation of rats’ diet with PSO separately or jointly with BM on the fatty acid (FA), cholesterol, malondialdehyde (MDA), and tocopherols concentrations in femoral muscles. Sprague‐Dawley rats (n = 36) are fed control diet (group C) or experimental diets supplemented only with 0.15 ml PSO/day (group G) or together with BM (group GM). After 21 weeks of supplementation, muscles are subjected to either gas (FA and cholesterol) or liquid (conjugated FA, tocopherols, and MDA) chromatographic analyses. Applied diets do not influence negatively health and welfare of animals. Conjugated linolenic acid (CLnA) isomers, predominating in PSO, are converted into ct/tc conjugated dienes (CD), with rumenic acid being the main CD, and incorporated into muscles. Supplementation of diet with PSO decreases the cholesterol and MDA contents in muscles. Influence of PSO and BM on activity of desaturases results in varied polyunsaturated FA (PUFA) content. Some PUFA may be converted into conjugated FA either exogenously or as a result of enzymatic or non‐enzymatic processes.Practical Applications: Dietary sources of conjugated linolenic acid isomer, e.g., PSO and BM, are known for their beneficial properties and thus willingly consumed world‐wide. Limited safety information of their simultaneous use is available despite their over‐consumption and may probably cause adverse effects. PSO and BM given to rats improves a lipid profile of femoral muscles, decreases cholesterol, increases polyunsaturated fatty acids and rumenic acid content, and counteracts lipid oxidation. These results may be a starting point for experiments conducted on farm animals considering their supplementation with PSO in order to possible improvement of nutritional value of their meat. After detailed surveys confirming beneficial influence of both supplements on human health and well‐being, these botanicals may be safely introduced into human diet.This study evaluates the influence of supplementation of rats’ diet with pomegranate seed oil separately or jointly with bitter melon extract on fatty acid, cholesterol, malondialdehyde, and tocopherols concentrations in femoral muscles. After 21 weeks of supplementation, muscles are subjected to either gas or liquid chromatographic analyses. Supplementation of diet with pomegranate seed oil decreases cholesterol and malondialdehyde contents.

Layered Double Hydroxides for the Catalytic Isomerization of Linoleic Acid to Conjugated Linoleic Acids (CLAs)

Several hydrotalcite-type compounds with different divalent (Mg2+, Ni2+, Cu2+, Zn2+) and trivalent (Al3+, Cr3+) cations and different ratio compositions were tested for the isomerization of linoleic acid in order to study their role on the obtention of specific conjugated linoleic acids (CLAs) with anticarcinogenic and nutritional properties. This is a complex reaction due to the high number of possible isomers of linoleic acid together with the significant competition of the isomerization reaction with other secondary undesired reactions. All catalysts showed very high conversions of linoleic acid, but condensation products were mainly obtained, especially for the hydrotalcite-type compounds with higher Mg/Al ratios due to their higher Brønsted basicity and for the catalysts with higher Ni2+ content or with the presence of Cu2+, Zn2+ in the layers because of the influence of the higher acidity of these cations on the Brønsted basicity of the hydroxides. The best results were achieved for the catalysts with Mg/Al ratio around 2.5–3, resulting in 29–38% of selectivity to the identified CLAs.

Efficacy of methyl ester of conjugated linoleic acid (t10,c12 isomer) for sows and cows for reproduction.

A mixture of methylated conjugated linoleic acid (CLA) isomers (t10,c12 and c9,t11) in equal proportions is the subject of this assessment. The active substance is considered to be CLA (t10,c12) methyl ester (ME). The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) of EFSA previously issued an opinion on the safety and efficacy of the product, in which it could not conclude on the efficacy of this additive for sows for reproduction and for cows for reproduction. The European Commission asked EFSA to deliver an opinion on the efficacy of this additive for sows and cows for reproduction, based on additional data submitted by the applicant. The FEEDAP Panel has performed the assessment of the new data following an approach in line with the principles laid down in Regulation (EC) No 429/2008 and the relevant guidance documents. In relation to the data on efficacy in sows for reproduction, owing to methodological shortcomings of the study submitted, including the duration of the study and the limited biological relevance of the effect observed, the FEEDAP Panel cannot conclude on the efficacy of CLA (t10,c12)‐ME for sows for reproduction. The data related to dairy cows indicate that dietary CLA (t10,c12)‐ME supplementation in the late dry period and/or lactation period showed an increase of the probability of pregnancy and a reduction of time to conception in the same reproductive cycle. However, considering that the minimum duration of efficacy studies for reproductive parameters is of at least two reproductive cycles, the FEEDAP Panel is not in a position to conclude on the efficacy of the additive for cows for reproduction.

Tissue-dependent effects of cis-9,trans-11- and trans-10,cis-12-CLA isomers on glucose and lipid metabolism in adult male mice

Mixtures of the two major conjugated linoleic acid (CLA) isomers trans-10,cis-12-CLA and cis-9,trans-11-CLA are used as over the counter supplements for weight loss. Because of the reported adverse effects of CLA on insulin sensitivity in some mouse studies, we sought to compare the impact of dietary t10c12-CLA and c9t11-CLA on liver, adipose tissue, and systemic metabolism of adult lean mice. We fed 8 week-old C57Bl/6J male mice with low fat diets (10.5% Kcal from fat) containing 0.8% t10c12-CLA or c9t11-CLA for 9 or 38 days. Diets containing c9t11-CLA had minimal impact on the endpoints studied. However, 7 days after starting the t10c12-CLA diet, we observed a dramatic reduction in fat mass measured by NMR spectroscopy, which interestingly rebounded by 38 days. This rebound was apparently due to a massive accumulation of lipids in the liver, because adipose tissue depots were visually undetectable. Hepatic steatosis and the disappearance of adipose tissue after t10c12-CLA feeding was associated with elevated plasma insulin levels and insulin resistance, compared to mice fed a control diet or c9t11-CLA diet. Unexpectedly, despite being insulin resistant, mice fed t10c12-CLA had normal levels of blood glucose, without signs of impaired glucose clearance. Hepatic gene expression and fatty acid composition suggested enhanced hepatic de novo lipogenesis without an increase in expression of gluconeogenic genes. These data indicate that dietary t10c12-CLA may alter hepatic glucose and lipid metabolism indirectly, in response to the loss of adipose tissue in mice fed a low fat diet.

Effect of pomegranate seed oil on fatty acids composition of &lt;i&gt;Oreochromis niloticus&lt;/i&gt; trough supplemented diet

Several health benefits have been attributed to conjugated linolenic acid isomers (CLnA). In this study, the diet for Nile tilapia was supplied with pomegranate seed oil (at 2.1%) as source of CLnA. The diet was provided to the fish for 15 and 30 days. The punic acid (40.58-53.77 mg g -1 of total lipids) was incorporated into Nile tilapia fillet after 15 and 30 days of experiment, respectively. When compared to the control diet, the level of total saturated fatty acids in fish were slightly increased. No change in the total amount of monounsaturated fatty acid was observed. The pomegranate seed oil diet was effective in the transference of CLnA to Nile tilapia.

IMPORTÂNCIA DO ÁCIDO LINOLEICO CONJUGADO (CLA) EM PRODUTOS DE ORIGEM ANIMAL

O termo CLA descreve um conjunto de isômeros geométricos do ácido linoleico com propriedades bioativas distintas, que têm duas duplas ligações separadas por apenas uma ligação simples. Assim, este trabalho trata-se de uma revisão bibliográfica baseada na literatura especializada, fundamentado através de consulta a artigos científicos selecionados em diferentes bases de dados com o objetivo de dar enfoque à importância do ácido linoleico conjugado (CLA) em produtos de origem animal e seus benefícios à saúde humana. Nesse contexto, em alimentos de origem animal é possível encontrar esse composto natural, principalmente na gordura do leite, carne e em alimentos naturalmente enriquecidos com este ácido e seus isômeros. O CLA tem propriedades bioativas distintas e é originário da biohidrogenação incompleta dos ácidos linoleico e linolênico realizada pelas bactérias ruminais ou da desaturação do trans-11 na glândula mamária e no intestino delgado. Os benefícios biológicos do CLA e dos isômeros cis-9 e trans-11, como um componente natural da gordura do leite, tem efeito anticarcinogênico, incluindo carcinomas na epiderme, tecido mamário e gastrintestinal. Dietas suplementadas com gorduras e a relação concentrado: volumoso, assim como a efetividade da fibra do volumoso podem aumentar a produção de leite, diminuir a produção de gordura e alterar seu perfil em ácidos graxos. Pesquisas avaliando os níveis de CLA nos produtos de origem animal e o seu efeito benéfico sobre a saúde e qualidade de vida do homem têm apresentado resultados satisfatórios, embora muitas vezes controversos, sendo necessários novos estudos para comprovar os resultados e a segurança na utilização desse composto, para que possa se determinar a sua real eficácia.

Trans10, cis12-conjugated linoleic acid exhibits a stronger antioxidant capacity than cis9, trans11-conjugated linoleic acid in primary cultures of laying hen hepatocytes

The objective of this study consisting of 2 trials was to investigate the antioxidant role of conjugated linoleic acid (CLA) isomers (c9, t11-CLA and t10, c12-CLA) and the underlying mechanism by which they act in modulating redox status in a primary laying hen hepatocyte culture. In trial 1, the cytotoxicity of CLA isomers or linoleic acid (LA) (0, 25, 50, 100, 200, 400, 800 μmol/L) was evaluated by 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay. The concentration of CLA isomers or LA (25, 50, 100 μmol/L) for proper antioxidant activity was evaluated by measuring the antioxidant enzyme activity. In trial 2, there were 5 groups: control group, cells were untreated; H2O2 group, cells were exposed to 4mmol/L H2O2 for 2h; c9, t11 or t10, c12 or LA group, cells were treated with c9, t11-CLA or t10, c12-CLA or LA for 24h and then exposed to 4mmol/L H2O2 for 2h. Trial 1 showed that the non-toxic dose range for CLA isomers was 0 to 200 μmol/L. The optimum concentration of c9, t11-CLA and t10, c12-CLA for trial 2 was 100 μmol/L. In trial 2, pretreatment with t10, c12-CLA but not c9, t11-CLA attenuated the increase in reactive oxygen species (ROS) compared to hydrogen peroxide (H2O2) group (P < 0.05). t10, c12-CLA elevated the superoxide dismutase (SOD) and catalase (CAT) activities compared with the H2O2 group (P < 0.05). In addition, t10, c12-CLA up-regulated the mRNA expression of nuclear factor E2-related factor-2 (Nrf2) as well as its target genes, Cu-Zn superoxide dismutase (SOD1) and CAT (P < 0.05). Pretreatment with t10, c12-CLA but not c9, t11-CLA decreased Nrf2 protein expression in the cytoplasm and increased Nrf2 protein expression in the nucleus compared with the H2O2 group (P < 0.05). The results indicate that t10, c12-CLA exhibits a stronger antioxidant capacity than c9, t11-CLA in primary cultured laying hen hepatocytes. t10, c12-CLA increases the activity and mRNA expression of antioxidant enzymes via facilitating nuclear translocation of Nrf2.

ANTIOXIDANT ACTIVITY OF CONJUGATED LINOLEIC ACID

Objective: The objective of the present study is to evaluate the antioxidant effect of conjugated linoleic acid (CLA). CLA is a collective term for a group of positional and geometric isomers of linoleic acid with conjugated double bond system. CLA is found in milk products and ruminant meat. CLA has been proved to be having many health benefits, one of them one being antioxidant effect.Methods: Various methods are used to find out the antioxidant effect of CLA. They are 1,1- diphenyl-2-picrylhydrazyl free radical scavenging assay, hydroxy radical scavenging assay, nitrous oxide radical scavenging assay, reducing power method, and phosphomolybdenum antioxidant assay. All these methods were done to test the antioxidant activity of CLA.Results: Standards error of mean calculated for all the tests. Statistical analysis done using one-way analysis of variance between the groups and SPSS software version 20 is used. p&lt;0.05 is considered statistically significant. All the tests are statistically significant.Conclusion: As p values for all the tests came significant, and it was concluded that CLA has got antioxidant property. CLA could protect membranes composed of 1-palmitoyl 2-linoleoyl phosphatidylcholine from oxidative modification under conditions of metal ion-dependent or -independent oxidative stress. Finally, it was concluded that CLA has got potential health benefits such as weight reduction, antiaging, and antioxidative properties.

Effect of Pufa Substrates on Fatty Acid Profile of Bifidobacterium breve Ncimb 702258 and CLA/CLNA Production in Commercial Semi-Skimmed Milk

Current research on lipids is highlighting their relevant role in metabolic/signaling pathways. Conjugated fatty acids (CFA), namely isomers of linoleic and linolenic acid (i.e. CLA and CLNA, respectively) can positively modulate inflammation processes and energy metabolism, promoting anti-carcinogenic and antioxidant effects, improved lipid profiles and insulin resistance, among others. Bioactive doses have been indicated to be above 1 g/d, yet these cannot be achieved through a moderate intake (i.e. 1–2 servings) of natural sources, and certain CLA-containing products have limited commercial availability. Such handicaps have fueled research interest in finding alternative fortification strategies. In recent years, screening of dairy products for CFA-producing bacteria has attracted much attention and has led to the identification of some promising strains, including Bifidobacterium breve NCIMB 702258. This strain has shown interesting producing capabilities in model systems as well as positive modulation of lipid metabolism activities in animal studies. Accordingly, the aim of this research work was to assay B. breve NCIMB 702258 in semi-skimmed milk to produce a probiotic fermented dairy product enriched in bioactive CLA and CLNA. The effect of substrates (LA, α-LNA and γ-LNA) on growth performance and membrane fatty acids profile was also studied, as these potential modifications have been associated to stress response. When tested in cys-MRS culture medium, LA, α-LNA and γ-LNA impaired the fatty acid synthesis by B. breve since membrane concentrations for stearic and oleic acids decreased. Variations in the C18:1 c11 and lactobacillic acid concentrations, may suggest that these substrates are also affecting the membrane fluidity. Bifidobacterium breve CFA production capacity was first assessed in cys-MRS with LA, α-LNA, γ-LNA or all substrates together at 0.5 mg/mL each. This strain did not produce CFA from γ-LNA, but converted 31.12% of LA and 68.20% of α-LNA into CLA and CLNA, respectively, after incubation for 24 h at 37 °C. In a second phase, B. breve was inoculated in a commercial semi-skimmed milk with LA, α-LNA or both at 0.5 mg/mL each. Bifidobacterium breve revealed a limited capacity to synthesize CLA isomers, but was able to produce 0.062–0.115 mg/mL CLNA after 24 h at 37 °C. However, organoleptic problems were reported which need to be addressed in future studies. These results show that although CFA were produced at too low concentrations to be able to achieve solely the bioactive dose in one daily portion size, fermented dairy products are a suitable vector to deliver B. breve NCIMB 702258.

Conversion of dietary trans-vaccenic acid to trans11,cis13-conjugated linoleic acid in the rat lactating mammary gland by Fatty Acid Desaturase 3-catalyzed methyl-end Δ13-desaturation

In vitro, the rat Fatty Acid Desaturase 3 (FADS3) gene was shown to code for an enzyme able to catalyze the unexpected Δ13-desaturation of trans-vaccenic acid, producing the trans11,cis13-conjugated linoleic acid (CLA) isomer. FADS3 may therefore be the first methyl-end trans-vaccenate Δ13-desaturase functionally characterized in mammals, but the proof of this concept is so far lacking in vivo. The present study therefore aimed at investigating further the putative in vivo synthesis of trans11,cis13-CLA from dietary trans-vaccenic acid in rodents. During one week of pregnancy and two weeks post-partum, Sprague-Dawley female rats were fed two diets either high (10.0% of fatty acids and 3.8% of energy intake) or low (0.4% of fatty acids and 0.2% of energy intake) in trans-vaccenic acid. The trans11,cis13-CLA was specifically detected, formally identified and reproducibly quantified (0.06% of total fatty acids) in the mammary gland phospholipids of lactating female rats fed the high trans-vaccenic acid-enriched diet. This result was consistent with FADS3 mRNA expression being significantly higher in the lactating mammary gland than in the liver. Although the apparent metabolic conversion is low, this physiological evidence demonstrates the existence of this new pathway described in the lactating mammary gland and establishes the FADS3 enzyme as a reliable mammalian trans-vaccenate Δ13-desaturase in vivo.

The fate of linoleic acid on Saccharomyces cerevisiae metabolism under aerobic and anaerobic conditions.

Saccharomyces cerevisiae has been widely used for fermenting food and beverages for over thousands years. Its metabolism together with the substrate composition play an important role in determining the characteristics of the final fermented products. We previously showed that the polyunsaturated fatty acid, linoleic acid, which is present in the grape juice at trace levels, significantly affected the development of aroma compounds of the wines. However, the effect of linoleic acid on the overall cell metabolism of S. cerevisiae is still not clear. Therefore, we aimed to unlock the metabolic response of S. cerevisiae to linoleic acid using metabolomics and isotope labelling experiments. We cultured the cells on a minimal mineral medium supplementing them with linoleic acid isomers and 13C-linoleic acid. Both intracellular and extracellular metabolite profiles were determined using gas chromatography coupled to mass spectrometry (GC-MS) to investigate which S. cerevisiae pathways were affected by linoleic acid supplementation. The utilisation of linoleic acid by S. cerevisiae had a significant impact on the primary carbon metabolism increasing the glucose consumption and the ethanol production under anaerobic condition. The energetic state of the cell was, therefore, affected and the glycolytic pathway, the TCA cycle and the amino acid production were up-regulated. We also observed that linoleic acid was transported into the cell and converted into other fatty acids affecting their profile even under anaerobic condition. Our data clearly shows that linoleic acid supplementation in growth medium increased glucose consumption and ethanol production by S. cerevisiae under anaerobic condition. We also suggest that S. cerevisiae might be able to perform an alternative anaerobic pathway to β-oxidation, which has not been reported yet.