Conjugated linoleic acid alleviates glycolipid metabolic disorders by modulating intestinal microbiota and short-chain fatty acids in obese rats.

Although conjugated linoleic acid (CLA) has been shown to have anti-obesity properties, the effect and mechanism of CLA in alleviating glycolipid metabolism disorders remains unclear. In this work, it was observed that rats fed a high-fat diet (HFD) had lower body weight and body fat levels after 9 weeks of low-dose and high-dose CLA interventions. The results of blood biochemical indices showed that CLA significantly reduced the levels of total cholesterol, triglycerides, fasting blood glucose and insulin. Additionally, high-dose CLA could restore the intestinal microbiota composition, including increasing the relative abundances of short-chain fatty acid (SCFA)-producing microbiota, such as Dubosiella, Faecalibaculum and Bifidobacterium; decreasing the relative abundances of Enterococcus and Ruminococcus_2; and increasing the content of SCFAs in feces and serum. Further analysis showed that high-dose CLA could increase the expression levels of Insr, Irs-2, Akt and Glut4 in the liver tissue of HFD-induced obese rats. Consistently, high dose of CLA could reversibly improve the downregulation of INSR, AKT, PI3K and GLUT4 protein expression caused by HFD and reverse the decline in AKT phosphorylation levels. Correlation clustering analysis with a heatmap showed that the changes in specific microbiota induced by high-dose CLA were correlated with changes in obesity-related indices and gene expression. The molecular docking analysis showed that the molecular docking of SCFAs with the IRS-2, AKT and GLUT4 proteins had high linking activity. The results supported that CLA can alleviate glycolipid metabolic imbalances associated with obesity by altering the intestinal microbiota to induce the production of SCFAs and thereby activate the INSR/IRS-2/AKT/GLUT4 pathway. This study supports CLA may be preferentially used by the intestinal microbiota of the host to promote its health.

Preparation of Conjugated Linoleic Acid by Ultrasound-assisted Nanonickel Catalyst Isomerization of Sunflower Oil.

A homemade nanonickel catalyst was made by the ultrasonic liquid-phase reduction method, characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and applied to the isomerization reaction of high linoleic acid sunflower oil. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and particle size analysis showed that the homemade nickel particles were spherical, uniformly dispersed, less agglomerated, 20 to 75 nm in size, and nanoscale nickel powder. Compared with commercially available Raney nickel, the homemade nanonickel powder has a larger specific surface area, smaller pore size and higher catalytic activity. The X-ray diffraction spectrum of the homemade nanonickel powder had distinct diffraction peaks at its characteristic peaks which indicated that the powder was pure nickel. The nanometal nickel particles are fully dispersed in high oleic sunflower oil under the action of ultrasound. The results showed that it could effectively reduce the activation reaction time of nanonickel, and the conversion rate of conjugated linoleic acid could reach 86.24%. The process of activating the catalyst is omitted, the number of times of repeated uses of the nanonickel catalyst is increased, and the environmental pollution of the production is avoided. To obtain sunflower oil rich in CLA, it also provides a new idea for the preparation of conjugated linoleic acid.

Functional milk fat enriched in conjugated linoleic acid prevented liver lipid accumulation induced by a high-fat diet in male rats.

The aim was to investigate the potential effect of functional milk fat (FMF), naturally enriched in conjugated linoleic acid, on the prevention of liver lipid accumulation and some biochemical mechanisms involved in the liver triacylglycerol (TAG) regulation in high-fat (HF) fed rats. Male Wistar rats were fed (60 days) with S7 (soybean oil, 7%) or HF diets: S30 (soybean oil, 30%), MF30 (soybean oil, 3% + milk fat -MF-, 27%) or FMF30 (soybean oil, 3% + FMF, 27%). Nutritional parameters, hepatic fatty acid (FA) composition, liver and serum TAG levels, hepatic TAG secretion rate (TAG-SR), lipoprotein lipase (LPL) activity in adipose tissue and muscle, activities and/or mRNA levels of lipogenic and ß-oxidative enzymes, and mRNA levels of transcription factors and FA transport proteins were assessed. The hepatic lipid accumulation induced by the S30 diet was associated with increased mRNA levels of FA transporters; and it was prevented by FMF through an increase in the hepatic TAG-SR, carnitine palmitoyltransferase-1a activity and peroxisome proliferator-activated receptor alpha mRNA levels, as well as by a reduction of the mRNA levels of FA transporters. The hypotriacylglyceridaemia observed in S30 was related with an increased LPL activity in adipose tissue and it was reverted by FMF through the increased hepatic TAG-SR. In brief, FMF prevented the liver lipid accumulation induced by HF diets by increasing the hepatic TAG-SR and ß-oxidation, and reducing the hepatic FA uptake. The increased hepatic TAG-SR induced by FMF could be responsible for the attenuation of serum TAG alterations.

Conjugated Linoleic Acid-Curcumin Attenuates Cognitive Deficits and Oxidative Stress Parameters in the Ethidium Bromide-Induced Model of Demyelination.

Oxidative stress has been shown to play an important role in the pathogenesis of multiple sclerosis (MS). Curcumin (CUR), an antioxidant compound, can be a potent treatment for neurodegenerative diseases, such as MS. CUR has poor bioavailability; therefore, it is used in nanoforms to increase its bioavailability. In the present study, the effects of CUR and conjugated linoleic acid-CUR (Lino-CUR) on spatial memory and oxidative stress in a putative animal model of MS were investigated. Forty-nine adult male Wistar rats (250 ± 50 g) were randomly divided into seven groups (n = 7): control, sham, ethidium bromide (EB), CUR (20 and 40 µg/kg) + EB, and Lino-CUR (20 and 40 µg/kg) + EB groups. Following MS induction, the groups were treated for 5 consecutive days. Finally, spatial memory and levels of oxidative stress parameters were assessed. Treatment with CUR and Lino-CUR at two doses significantly improved spatial memory and reduced oxidative stress parameters in the experimental models of MS. Furthermore, the effects of high dose (40 µg/kg) of Lino-CUR were more remarkable. These findings suggest that the microinjection of CUR in its synthetic form Lino-CUR significantly ameliorated spatial memory, through the reduction of oxidative stress markers in the brain of studied animals as a rat model of MS.

Soy oil conjugated linoleic acid production with solar light photoisomerization.

The objectives were (1) to produce soy oil conjugated linoleic acid (CLA) triacylglycerides in large quantities with solar light photoisomerization, utilizing iodine as a photosensitizer, (2) to study the temperature variation in the photoisomerized oil during various hours of the day, and (3) to study the variations in solar light intensity during various hours of the day. A 0.5% iodine containing soy oil in glass box with a glass lid was photoisomerized, under natural solar light for 0, 11, and 27 days, and CLA isomers were determined with gas chromatography with flame ionization detector. After 27 days of solar light photoisomerization, the cis-9, trans-11 CLA; other cis, trans CLA; trans-10, cis-12 CLA; trans, trans CLA, and total CLA were found to be 0.62 ± 0.05%, 1.04 ± 0.09%, 0.54 ± 0.11%, 6.16 ± 0.68%, and 8.37 ± 0.90%, respectively. The concentration of CLA isomers between 0 and 11 days was significantly different (p < .05), and the concentration of CLA isomers between 0 and 27 days was also significantly different (p < .05). There is no significant difference (p > .05) in CLA concentration between 11 and 27 days treatment. The CLA was not found in control soy oil samples. The CLA isomers were measured with GDFID in 45 min instead of 120min. The temperature of the edible oil in glass boxes ranged from 26 °C (8 a.m.) to 56 °C (1 p.m.). The light intensity ranged from 4,146 lux (7 p.m.) to 95,490 lux (12 p.m.). Glass lid on the glass box affected light transmission to a small but statistically significant extent (p < .05). The CLA isomers could be energy efficiently and inexpensively produced in soy oil by solar light photoisomerization, at low temperature and without needing expensive reactor vessels or catalysts. PRACTICAL APPLICATION: CLA was produced effectively with the iodine sensitized solar light photoisomerization. CLA is produced in large quantities, inexpensively, for possible food additive applications. Produced CLA is in the form of stable triacylglycerides.

Enhancement of physicochemical and encapsulation stability of O1/W/O2 multiple nanoemulsions loaded with coenzyme Q10 or conjugated linoleic acid by incorporating polyphenolic extract.

Multiple O1/W/O2 nanoemulsions and O1/W nanoemulsions fortified with CLA or CoQ10 were produced using extra virgin olive or olive pomace oil and were also incorporated with polyphenols extracted from olive kernel to enhance their kinetic and chemical stability. They were prepared using a high-speed ultrasonic homogenizer. Specifically, nanoemulsions with 6 wt% lipid phase and 6 wt% non-ionic emulsifier (Tween 40) were produced and they demonstrated a droplet diameter >200 nm and high encapsulation stability during 30 days of storage at 4 °C or 25 °C. The incorporation of CLA or CoQ10 and polyphenolic compounds facilitated the homogenization of emulsions, reducing the droplet size and enhancing their chemical stability, and their bioactive retention values were >79%. O1/W/O2 nanoemulsions were produced using a mixture of non-ionic emulsifiers (Span 20 and Tween 40) and the O1/W enriched nanoemulsion as the dispersed phase. All multiple emulsions showed a bimodal droplet size distribution and Newtonian behavior while polyphenols facilitated their homogenization. Both vegetable oils resulted in samples with high kinetic and chemical stability; the bioactive retention values were found to be >80% at the end of 30 days of storage at 4 °C or 25 °C. Extra virgin olive oil resulted in more stable nanoemulsions in regards to kinetic and chemical stability at 4 °C, showing limited creaming and sedimentation boundary. Multiple nanoemulsions with the lowest initial droplet size presented the lowest droplet diameter growth and phase separation and the highest retention values. By comparing O1/W nanoemulsions and O1/W/O2 nanoemulsions, we noted that the reduction in the total phenolic content and antioxidant activity during storage was higher in the O1/W type. However, both delivery systems protected CLA and CoQ10 presenting high retention during storage. FTIR spectra before and after ultrasonic homogenization indicated that the sonication process did not significantly affect the lipid phase of O1/W/O2 nanoemulsions.

cis 9, trans 11, but not trans 10, cis 12 CLA isomer, impairs intestinal epithelial barrier function in IPEC-J2 cells and mice through activation of GPR120-[Ca2+]i and the MLCK signaling pathway.

This study aimed to investigate the effects of conjugated linoleic acid (CLA) on intestinal epithelial barrier function and explore the underlying mechanisms. IPEC-J2 cells and mice were treated with different CLA isomers. The intestinal epithelial barrier function determined by transepithelial electrical resistance (TEER), the expression of tight junction proteins, and the involvement of G-protein coupled receptor 120 (GPR120), intracellular calcium ([Ca2+]i) and myosin light chain kinase (MLCK) were assessed. In vitro, c9, t11-CLA, but not t10, c12-CLA isomer, impaired epithelial barrier function in IPEC-J2 by downregulating the expression of tight junction proteins. Meanwhile, c9, t11-CLA isomer enhanced GPR120 expression, while knockdown of GPR120 eliminated the impaired epithelial barrier function induced by c9, t11-CLA isomer. In addition, c9, t11-CLA isomer increased [Ca2+]i and activated the MLCK signaling pathway in a GPR120-dependent manner. However, chelation of [Ca2+]i reversed c9, t11-CLA isomer-induced MLCK activation and the epithelial barrier function impairment of IPEC-J2. Furthermore, inhibition of MLCK totally abolished the impairment of epithelial barrier function induced by c9, t11-CLA. In vivo, dietary supplementation of c9, t11-CLA rather than t10, c12-CLA isomer decreased the expression of intestinal tight junction proteins and GPR120, increased intestinal permeability, and activated the MLCK signaling pathway in mice. Taken together, our findings showed that c9, t11-CLA, but not t10, c12-CLA isomer, impaired intestinal epithelial barrier function in IPEC-J2 cells and mice through activation of GPR120-[Ca2+]i and the MLCK signaling pathway. These data provided new insight into the regulation of the intestinal epithelial barrier by different CLA isomers and more references for CLA application in humans and animals.

Decreased Metabolic Flexibility in Skeletal Muscle of Rat Fed with a High-Fat Diet Is Recovered by Individual CLA Isomer Supplementation via Converging Protective Mechanisms.

Energy balance, mitochondrial dysfunction, obesity, and insulin resistance are disrupted by metabolic inflexibility while therapeutic interventions are associated with improved glucose/lipid metabolism in skeletal muscle. Conjugated linoleic acid mixture (CLA) exhibited anti-obesity and anti-diabetic effects; however, the modulatory ability of its isomers (cis9, trans11, C9; trans10, cis12, C10) on the metabolic flexibility in skeletal muscle remains to be demonstrated. Metabolic inflexibility was induced in rat by four weeks of feeding with a high-fat diet (HFD). At the end of this period, the beneficial effects of C9 or C10 on body lipid content, energy expenditure, pro-inflammatory cytokines, glucose metabolism, and mitochondrial efficiency were examined. Moreover, oxidative stress markers, fatty acids, palmitoyletanolamide (PEA), and oleyletanolamide (OEA) contents along with peroxisome proliferator-activated receptors-alpha (PPARα), AKT, and adenosine monophosphate-activated protein kinase (AMPK) expression were evaluated in skeletal muscle to investigate the underlying biochemical mechanisms. The presented results indicate that C9 intake reduced mitochondrial efficiency and oxidative stress and increased PEA and OEA levels more efficiently than C10 while the anti-inflammatory activity of C10, and its regulatory efficacy on glucose homeostasis are associated with modulation of the PPARα/AMPK/pAKT signaling pathway. Our results support the idea that the dissimilar efficacy of C9 and C10 against the HFD-induced metabolic inflexibility may be consequential to their ability to activate different molecular pathways.

Genetic determinates for conjugated linolenic acid production in Lactobacillus plantarum ZS2058.

AIMS: To investigate the genetic determinates for conjugated linolenic acid (CLNA) production in Lactobacillus plantarum ZS2058, a high CLNA producer. METHODS AND RESULTS: After culturing with α-linolenic acid (ALA) in the medium, the fatty acid compositions of supernatant fluid and cell pellets were analysed via GC-MS. cis9,trans11,cis15-CLNA was identified to be the predominant isomer. And during CLNA production, 10-hydroxy-cis12-cis15-octadecenoic acid (10-HOEA) and 10-oxo-cis12-cis15-octadecenoic acid (10-OXOA) were accumulated. The E. coli recombinants harbouring genes encoding myosin-cross-reactive antigen (MCRA), short-chain dehydrogenase/oxidoreductase (DH) and acetoacetate decarboxylase (DC), respectively, were analysed for their roles in CLNA production. The results indicated that MCRA converted ALA to 10-HOEA, following converted to 10-OXOA by DH. While with the combination of three recombinants, ALA could be transformed into CLNA plus 10-HOEA and 10-OXOA. When the three genes were deleted, none of the L. plantarum ZS2058 knockout mutants could produce any CLNA, after complementation, and all the complementary mutants recovered the CLNA-production ability at similar levels as the wild strain. CONCLUSIONS: Lactobacillus plantarum ZS2058 produced CLNA from ALA with 10-HOEA and 10-OXOA as intermediates. The triple-component isomerase of MCRA, DH and DC was the unique genetic determinant for CLNA generation. SIGNIFICANCE AND IMPACT OF THE STUDY: The current results firstly provided conclusive evidence that the triple-component isomerase complex was shared by both CLA and CLNA production in lactobacilli.

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.

Differing responses in milk composition from introducing rapeseed and naked oats to conventional and organic dairy diets.

Dairy products are often considered challenging for health due to their saturated fatty acid content, yet they also provide beneficial nutrients, some unique to ruminants. The degree of fat saturation is influenced by cows' diets; grazing pasture enhances unsaturated fatty acids in milk compared with conserved forages. These benefits can be partially mimicked by feeding oilseeds and here we consider the impact on milk composition in a 2 × 2 trial, feeding rapeseed to both conventional and organic cows, finding very differing lipid metabolism in the 4 experimental groups. For milk fat, benefits of organic rather than conventional management (+39% PUFA, +24% long chain omega-3 and +12% conjugated linoleic acid (CLA)) appear complementary to those from feeding rape (+43% MUFA, +10% PUFA, +40% CLA), combining to produce milk 16% lower SFA and higher in MUFA (43%), PUFA (55%) and CLA (59%). Organic and rape feeding provide less omega-3 PUFA than the conventional and control diets, yet contrary to expectations, together they almost doubled (+94%) the omega-3 concentration in milk, implying a 3.8 fold increase in net transfer from diet into milk. Organic and rape feeding also gave lower trace-elements and antioxidants in milk. Greater understanding of these phenomena might enhance the sustainability of dairying.

Effect of frying and storage on oxidative quality of conjugated linoleic-acid-rich soybean oil produced by photoisomerization using plantain as a model system.

BACKGROUND: Conjugated linoleic acid (CLA) is known to have beneficial properties to health. Naturally, in foods it is found in very low concentrations, and so these beneficial properties cannot be obtained. This study investigated the enrichment of soybean oil by photoisomerization, as well as assessing its oxidative stability during the frying process using plantain slices as a model system and after a storage period of 20 days at 60 °C. RESULTS: The oxidative stability of soybean oil enriched with CLA by photoirradiation was measured based on the peroxide, p-anisidine, and Totox values, as well as by the polyphenol content, tocopherol content and DPPH· scavenging capacity. The results obtained showed that a substantial amount of CLA was obtained by photoirradiation (31.73%). The oxidative stability values of the oil enriched with CLA showed good stability during a frying cycle; however, this stability decreased when it was stored and during the final frying cycles. CONCLUSIONS: The results obtained indicated that photoirradiation is a good technique for obtaining oils enriched with CLA, and in this way CLA can be incorporated into foods; however, it is necessary to add antioxidants to improve their stability. © 2019 Society of Chemical Industry.

Conjugated Linoleic Acid Isomers Trans-10, Cis-12 and Cis-9, Trans-11 Prevent Collagen-Induced Arthritis in a Direct Comparison.

Mixed-isomer conjugated linoleic acid (CLA) and the individual isomers, trans-10, cis-12 (CLAt10c12) and cis-9, trans-11 (CLAc9t11), decrease severity of collagen-induced arthritis (CA) when consumed after disease onset. Few studies have been conducted exploring the role of CLA in the prevention of autoimmune diseases. These studies suggest that isomer-specific effects may be occurring; however, a direct comparison of CLAt10c12 and CLAc9t11 has yet to be conducted. A study to compare the ability of CLAt10c12 and CLAc9t11 to prevent CA and assess their effects on early inflammation was performed. DBA/1 mice were fed a semipurified diet containing 6% corn oil (CO), 5.5% CO and 0.5% CLAt10c12, or 5.5% CO and 0.5% CLAc9t11 (n = 27 per diet) starting three weeks before CA primary immunization. Effects on disease incidence and severity, anticollagen antibodies, plasma and paw cytokines, and hepatic fatty acids were measured. Arthritis incidence was reduced by a minimum of 34% in mice fed either CLA isomer compared to those fed CO diet (p = 0.06). In mice that did develop arthritis (n = 9-12 mice per treatment), CLAt10c12 reduced arthritic severity to a greater extent than CLAc9t11 and CO (p = 0.03). CLA isomer treatment attenuated the increased hepatic arachidonic acid (ARA; 20:4n-6) observed with arthritis at one-week postonset (p = 0.03), while no differences in anticollagen antibodies or cytokines were observed between dietary treatments. These results suggest that CLA isomers may be effective at preventing specific immune-mediated inflammatory diseases, in part, through modulation of the ARA cascade.

Protective effect of Rumenic acid rich cow's milk against colitis is associated with the activation of Nrf2 pathway in a murine model.

Dietary supplementation with pure cis9, trans11 isomer of Conjugated Linoleic Acid -known as Rumenic Acid (RA)- improves cytoprotective defenses downstream through the activation of nuclear factor-E2-related factor-2(Nrf2). This capability, when Rumenic Acid is consumed in the form of foods, is still unknown. The ability of standard (St) or cow milk naturally-enriched in RA (En) to activate Nrf2 pathway and its impact on dextran sodium sulfate (DSS)-induced colitis was comparatively evaluated. Activity of Nrf2 pathway was investigated in colonic tissue of BALB/c mice, receiving 4-week supplement with skimmed milk (SK), St or St reinforced with pure RA (RSt) providing increasing RA dose (0, 124 or 404mg RA/kg-1 b.w, respectively). Next, the anti-oxidant/ anti-inflammatory effect produced by St or En treatment (383mg RA/kg-1 b.w.) was explored. Finally, macroscopic and histomorphologic features of colitis were evaluated in animals challenged with 5% (w/v) DSS, at the end of St or En treatment. Significant activation of Nrf2 pathway is associated with RSt and En intake (P<0.05), but not with SK or En treatment. En pre-treatment offers better protection, in comparison with St, against pro-oxidant, pro-inflammatory signs (P<0.01) and macroscopic signs triggered by DSS. It can be concluded that Nrf2 activation by higher RA amount contained in En is, at least in part, responsible for the improved protection associated with En intake against DSS-induced colitis.

Bacterial conjugated linoleic acid production and their applications.

Conjugated linoleic acid (CLA) has been shown to exert various potential physiological properties including anti-carcinogenic, anti-obesity, anti-cardiovascular and anti-diabetic activities, and consequently has been considered as a promising food supplement. Bacterial biosynthesis of CLA is an attractive approach for commercial production due to its high isomer-selectivity and convenient purification process. Many bacterial species have been reported to convert free linoleic acid (LA) to CLA, hitherto only the precise CLA-producing mechanisms in Propionibacterium acnes and Lactobacillus plantarum have been illustrated completely, prompting the development of recombinant technology used in CLA production. The purpose of the article is to review the bacterial CLA producers as well as the recent progress on describing the mechanism of microbial CLA-production. Furthermore, the advances and potential in the heterologous expression of CLA genetic determinants will be presented.

Absorption Kinetics of the Main Conjugated Linoleic Acid Isomers in Commercial-Rich Oil after Oral Administration in Rats.

This study aimed to assess the oral absorption and plasma kinetics of two main isomers contained in commercial conjugated linoleic acid (CLA)-rich oil (Tonalin TG-80), rumenic acid (RA), and C18:2 trans-10, cis-12. The isomer plasma disposition after the single oral dose of 3000 mg of Tonalin TG-80/kg, containing 1200 mg/kg of each isomer, was studied in rats. The isomer plasma concentrations were determined by gas chromatography with flame ionization detection. The plasma kinetics showed rapid oral absorption of RA and C18:2 trans-10, cis-12 (t1/2a 0.34 ± 0.09 and 0.53 ± 0.01 h) and slow elimination (t1/2ß 25.68 ± 3.29 and 18.12 ± 1.71 h); the maximal isomer plasma concentrations (Cmax) of 8.48 ± 0.98 and 7.67 ± 0.80 µg mL-1, respectively, were estimated at 2.08 ± 0.14 and 2.26 ± 0.11 h. Our results from a preclinical kinetic study in rats help to design future studies in humans for evaluating the CLA isomer dose-response.

Green Synthesis of Conjugated Linoleic Acids from Plant Oils Using a Novel Synergistic Catalytic System.

A novel and efficient method has been developed for converting plant oil into a specific conjugated linoleic acid (CLA) using a synergistic biocatalytic system based on immobilized Propionibacterium acnes isomerase (PAI) and Rhizopus oryzae lipase (ROL). PAI exhibited the greatest catalytic activity when immobilized on D301R anion-exchange resin under optimal conditions (PAI dosage of 12 410 U of PAI/g of D301R, glutaraldehyde concentration of 0.4%, and reaction conditions of pH 7.0, 25 °C, and 60 min). Up to 109 g/L trans-10,cis-12-CLA was obtained after incubation of 200 g/L sunflower oil with PAI (1659 U/g of oil) and ROL (625 mU/g of oil) at pH 7.0 and 35 °C for 36 h; the corresponding conversion ratio of linoleic acid (LA) to CLA was 90.5%. This method exhibited the highest proportion of trans-10,cis-12-CLA yet reported and is a promising method for large-scale production.

Strategies for Producing and Incorporating Conjugated Linoleic Acid-Rich Oils in Foods.

Conjugated linoleic acid (CLA) is in ruminant-derived foods and is known to combat obesity-related diseases. However, CLA levels in a healthy diet are too low to produce a clinical effect. Therefore, CLA has been produced by linoleic isomerization through fermentation and chemical catalysis. Many of these techniques are not practical for food production, but a recent development has enabled production of CLA-rich triglyceride vegetable oils from high linoleic acid oils by a minor modification of conventional food-oil processing techniques. These oils were used to produce common lipid-based food, such as margarine, shortenings, and salad dressings, whose quality was enhanced by the presence of CLA-rich oil and provided a significant CLA source. Meat and egg CLA content and subsequent food quality can also be increased by addition of dietary CLA. However, consumer awareness of CLA benefits needs to increase prior to commercial-scale production of CLA-rich oil.

Reaction pathway mechanism of thermally induced isomerization of 9,12-linoleic acid triacylglycerol.

BACKGROUND: To clarify the formation mechanism of trans linoleic acid isomers in edible oils during the heating process, trilinolein and trilinoelaidin, as representative oils, were placed in glass ampoules and sealed before heating at 180, 240 and 320 °C. The glass ampoules were removed at regular time intervals, and the contents were analyzed by infrared spectroscopy. The samples were then subjected to derivatization into their methyl esters for gas chromatographic analysis. RESULTS: Analysis results show that 9c,12c and 9t,12t fatty acids from trilinolein and trilinoelaidin molecules undergo chemical bond rotation, migration and degradation, leading to the formation of non-conjugated linoleic acids (NLAs), conjugated linoleic acids (CLAs) and aldehydes. The formation rate of isomers from the 9c,12c fatty acid is higher than that of the 9t,12t fatty acid. The production of aldehydes increases with heating temperature and time. The isomerization pathways involved in the formation of NLAs and CLAs during heating are clearly presented. CONCLUSION: These findings suggest possible pathways of NFA and CFA formation from heated trilinolein and trilinoelaidin, complement the mechanistic studies previously published in the literature, and provide a theoretical basis for future control of the quality and safety of fats and oils. © 2016 Society of Chemical Industry.

Atheroprotective effects of conjugated linoleic acid.

Atherosclerosis, the underlying cause of heart attack and strokes, is a progressive dyslipidaemic and inflammatory disease where monocyte-derived macrophage cells play a pivotal role. Although most of the mechanisms that contribute to the progression of atherosclerosis have been identified, there is limited information on those governing regression. Conjugated linoleic acid (CLA) is a generic term denoting a group of naturally occurring isomers of linoleic acid (18:2, n6) that differ in the position or geometry (i.e. cis or trans) of their double bonds. The most predominant isomers in ruminant fats are cis-9, trans-11 CLA (c9,t11-CLA), which accounts for more than 80% of CLA isomers in dairy products and trans-10, cis-12 CLA (t10,c12-CLA). Dietary administration of a blend of the two most abundant isomers of CLA has been shown to inhibit the progression and induce the regression of pre-established atherosclerosis. Studies investigating the mechanisms involved in CLA-induced atheroprotective effects are continually emerging. The purpose of this review is to discuss comprehensively the effects of CLA on monocyte/macrophage function in atherosclerosis and to identify possible mechanisms through which CLA mediates its atheroprotective effects.