CLA Isomers Research Articles

Production of Conjugated Linoleic Acid by Microwave‐Assisted and Ultrasound‐Assisted Alkali Isomerization: Effects of Microwave Power and Ultrasound Amplitude

AbstractConjugated linoleic acid (CLA) is commercially produced by alkali isomerization of linoleic acid (LNA). However, this method constitutes a relatively high content of undesirable CLA isomers. In present study, microwave‐assisted and ultrasound‐assisted alkali isomerization techniques were applied for production of CLA as an alternative to traditional alkali isomerization. This study was aimed to evaluate the isomerization degree of LNA, by using various process conditions such as microwave power, ultrasound amplitude, and their reaction times. The best conditions for LNA isomerization were a microwave power of 700 W and a reaction time of 6 h for microwave‐assisted alkali isomerization and an ultrasound amplitude of 100% and a reaction time of 6 h for ultrasound‐assisted alkali isomerization. Under determined conditions, microwave‐assisted alkali isomerization (97.21%) resulted in a higher isomerization degree compared to ultrasound‐assisted alkali isomerization (76.98%) while the content of undesirable CLA isomers in ultrasound‐assisted alkali isomerization (0.62%) was lower than that of microwave‐assisted alkali isomerization (1.87%). This study showed that application of the both techniques resulted in equal amounts of desirable CLA isomers. The content of desirable CLA isomers was 47.09% cis‐9, trans‐11 and 48.25% trans‐10, cis‐12 for microwave‐assisted alkali isomerization and 36.34% cis‐9, trans‐11 and 40.02% trans‐10, cis‐12 for ultrasound‐assisted alkali isomerization.

Optimization of conjugated linoleic acid production from safflower oil and purification by low temperature crystallization

The first objective of this study was to reveal the effect of temperature and time on the production of CLA isomers from safflower oil. For this purpose, CLA production was conducted at different temperatures (80–240 °C) and over different time durations (1–10 h). Alkali isomerisation gave a total conversion of 87.8% under the optimal conditions of 240 °C and 8 h (for maximum beneficial isomers), and produced 41.0% trans-10, cis-12, 40.4% cis-9, trans-11, and 6.4% undesirable CLA isomers. The second aim of this study was to determine the effect of temperature and solvents on the purification of CLA isomers. To achieve this, CLA solutions containing different solvents (acetone, methanol, and petroleum ether) were crystallized at several temperatures (0 to –85 °C). It was determined that although the highest CLA purities (94%) were obtained at –55 °C using acetone as the solvent with a yield of 38.1%, the highest yield (89.6%) was determined using petroleum ether at –85 °C with a purity of 88.1%. This paper presents methods to utilize safflower oil and low temperature crystallization process to inexpensively obtain beneficial CLA.

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.

Effect of dietary inclusion of different lipid supplements on quality and oxidative susceptibility of beef meat

The aim of this study was to evaluate the impact of dietary extruded flaxseed (EF) and/or rumen-protected (rp) lipids on beef meat quality and oxidation. In all, 63 crossbred heifers (Charolais × Limousin) were evenly distributed into seven experimental groups, balanced in terms of age and body weight (BW). The feeding groups differed in both, the dietary lipid source (EF and/or rp-conjugated linoleic acid (CLA), supplemented with vitamin E (VE)) and the supplementation length (90 or 180 days before slaughter); the same total amount of lipids was administered to the animals. With the respect of the control group, the α-linolenic acid content significantly increased and the n-6/n-3 ratio decreased in cattle groups fed with EF. The results also show that providing CLA and/or EF did not lead to an increase in CLA isomers (CLAs) in the lipid fraction of the meat. Our finding shows that administering EF for a shorter period with respect to longer, moderately enhance the nutritional value of the meat with regard to fat composition. No significant effects of dietary supplementation on TBA-reactive substances (TBARs) levels of fresh meat were observed; however, the protection provided by vitamin supplementation might become evident during meat storage under commercial retail conditions.

Chemical composition and seasonal changes in the fatty acid profile of Uruguayan “Colonia” Cheeses

The basic chemical composition and the fatty acid (FA) profile of Uruguayan Colonia cheese, consumed in the Mercosur region, were determined. 24 cheeses from different dairy farms: 10 elaborated in autumn and 14 in spring, were analyzed. Those cheeses are made from cow´s milk, whose diet was composed of 50% pasture system, 25% concentrate, and 25% silage reserves. The cheese making and ripening time were similar. Seasonal differences emerged in the profiles of saturated FA (SFA), unsaturated FA (UFA) and polyunsaturated FA (PUFA). The seasonal comparation of polyunsaturated FA (PUFA) as well as the CLA isomer such as C18:2 t10c12 showed significant differences (p < 0.05). CLA isomer such as C18:2 c9t11, showed no differences (p > 0.05). The atherogenesis index (AI) = 2.21 and thrombogenicity (IT) = 2.84, were calculated and discussed.

Fatty acid profile and oxidation tests of fat extracted from yogurt using rose hip seed oil.

Yogurt is a dairy product with a high nutritional value. However, like all milk products, it contains milk fat and is rich in saturated fatty acids. It would be desirable to enrich dairy products in poly- unsaturated fatty acids to increase dietary intake amongst consumers and improve their health. Also, some LAB bacteria are able to produce CLA and CLnA isomers from linoleic and linolenic acids. The aim of this study was to investigate the chemical properties and fatty acid profile of yogurt with the addition of 3.5% of rose hip seed oil. Yogurt was made from skimmed milk and yogurt starter culture YC-180 Ch. Hansen (Denmark), with the addition of 3.5% of rose hip seed oil. The peroxide value, acid value, iodine value, TBA rate and fatty acid profile were determined in fat extracted from the yogurt after 1 and 14 days of storage and in fresh rose hip seed oil. The fatty acid profile was determined using gas chromatographic methods with mass spectrometric detectors. Fat extracted from the yogurts had lower levels of peroxides than the fresh oil. It was more acidic and the iodine value was higher than in the fresh oil. Rose hip seed oil enriched the product with polyunsaturated fatty acids. After 14 days of storage, linoleic and linolenic acid levels had increased. Moreover, the content of myristic and palmitic acids had decreased. The rose hip seed oil added to the yogurt was less susceptible to oxidation. The content of un- saturated fatty acids in the yogurt increased with the addition of the oil, making yogurt with rose hip seed oil an excellent source of Ω-3 and Ω-6 fatty acids. Conjugated linoleic (CLA) and linolenic (CLnA) acids were not detected. However, yogurt manufactured with appropriate adjunct cultures and with the correct oil addition could be a natural source of CLA and CLnA in the human diet.

Fatty acid profile and oxidation tests of fat extracted from yogurt using rose hip seed oil [pdf

Background Yogurt is a dairy product with a high nutritional value. However, like all milk products, it contains milk fat and is rich in saturated fatty acids. It would be desirable to enrich dairy products in poly- unsaturated fatty acids to increase dietary intake amongst consumers and improve their health. Also, some LAB bacteria are able to produce CLA and CLnA isomers from linoleic and linolenic acids. The aim of this study was to investigate the chemical properties and fatty acid profile of yogurt with the addition of 3.5% of rose hip seed oil. Methods Yogurt was made from skimmed milk and yogurt starter culture YC-180 Ch. Hansen (Denmark), with the addition of 3.5% of rose hip seed oil. The peroxide value, acid value, iodine value, TBA rate and fatty acid profile were determined in fat extracted from the yogurt after 1 and 14 days of storage and in fresh rose hip seed oil. The fatty acid profile was determined using gas chromatographic methods with mass spectrometric detectors. Results Fat extracted from the yogurts had lower levels of peroxides than the fresh oil. It was more acidic and the iodine value was higher than in the fresh oil. Rose hip seed oil enriched the product with polyunsaturated fatty acids. After 14 days of storage, linoleic and linolenic acid levels had increased. Moreover, the content of myristic and palmitic acids had decreased. Conclusions The rose hip seed oil added to the yogurt was less susceptible to oxidation. The content of un- saturated fatty acids in the yogurt increased with the addition of the oil, making yogurt with rose hip seed oil an excellent source of O-3 and O-6 fatty acids. Conjugated linoleic (CLA) and linolenic (CLnA) acids were not detected. However, yogurt manufactured with appropriate adjunct cultures and with the correct oil addition could be a natural source of CLA and CLnA in the human diet.

Anti-inflammatory effects of conjugated linoleic acid isomers and essential fatty acids in bovine mammary epithelial cells

Fatty acids are important modulators of inflammatory responses, in particular, n-3 and n-6 essential fatty acids and CLA have received particular attention for their ability to modulate inflammation. The objectives of this study were to compare the effects of CLA and essential fatty acids on the expression of pro and anti- inflammatory cytokines and their protective efficacy against inflammatory status in mammary gland by an in vitro model based on bovine mammary epithelial cells (BME-UV1). Bovine mammary epithelial cells were treated with complete medium containing either 50 µM of cis-9, trans-11 CLA (c9,t11 CLA) or trans-10, cis-12 CLA (t10,c12 CLA) or (α)-linolenic acid (aLnA) or (γ)-linolenic acid (gLnA) or linoleic acid (LA). After 48 h by fatty acids administration the cells were treated for 3 h with 20 µM of lipopolysaccharide (LPS) to induce inflammatory stimulus. Reactive oxygen species (ROS) production after treatments was assessed to verify and to compare the potential protection of different fatty acids against LPS-induced oxidative stress. The messenger RNA abundance of bovine pro and anti-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and interleukine-10 (IL-10)) and peroxisome proliferator receptor-α/γ (PPARγ/α) were determined in BME-UV1 by real-time PCR. The results showed that cells treated with fatty acids and LPS increased ROS production compared with control cells. Among treatments, cells treated with c9,t11 CLA and t10,c12 CLA isomers revealed significant lower levels of ROS production compared with other fatty acids. All fatty acids reduced the gene expression of pro- and anti-inflammatory cytokines. Among fatty acids, t10,c12 CLA, LA and gLnA showed an homogeneous reduction of the three pro-inflammatory cytokines and this may correspond to more balanced and efficient physiological activity and may trigger a better protective effect. The PPARγ gene expression was significantly greater in cells treated with t10,c12 CLA, aLnA and LA, whereas the PPARα gene expression levels were significantly lower in cells treated with all different fatty acids, compared with the control. These results suggest that fatty acids inhibited the transcription of pro-inflammatory cytokines by the upregulation of PPARγ expression.

One-pot conjugated linoleic acid production from castor oil by Rhizopus oryzae lipase and resting cells of Lactobacillus plantarum.

Conjugated linoleic acid (CLA) has attracted as novel type of fatty acids having unusual health-promoting properties such as anticarcinogenic and antiobesitic effects. The present work employed castor oil as substrate for one-pot production of CLA using washed cells of Lactobacillus plantarum (L. plantarum) and lipases as catalysts. Among the screened lipases, the lipase Rhizopus oryzae (ROL) greatly assisted resting cells to produce CLA. Mass spectral analysis of the product showed that two major isomers of CLA were produced in the reaction mixture i.e. cis-9, trans-11 56.55% and trans-10, cis-12 43.45%. Optimum factors for CLA synthesis were found as substrate concentration (8mg/mL), pH (6.5), washed cell concentration (12% w/v), and incubation time of 20h. Hence, the combination of ROL with L. plantarum offers one pot production of CLA selectively using castor oil as a cost-effective substrate.

Trans-10,cis-12 conjugated linoleic acid (t10-c12 CLA) treatment and caloric restriction differentially affect adipocyte cell turnover in obese and lean mice

Caloric restriction (CR) is one of the most promising strategies for weight loss but is associated with loss of lean mass, whereas compounds such as trans-10,cis-12 conjugated linoleic acid (t10-c12 CLA) have been promoted as antiobesity agents. To compare the mechanisms of weight reduction by CR and t10-c12 CLA, body composition, glucose control, and characteristics of adipose tissue with respect to cell turnover (stem cells and preadipocytes, apoptosis and autophagy) and Tbx-1 localization were examined in obese db/db mice and lean C57BL/6J mice undergoing CR or fed CLA isomers (0.4% w/w c9-t11 or t10-c12) for 4 weeks. Our findings show that the t10-c12 CLA reduced whole-body fat mass by decreasing all fat depots (visceral, inguinal, brown/interscapular), while CR lowered both whole-body fat and lean mass in obese mice. t10-c12 CLA elevated blood glucose in both obese and lean mice, while glycemia was not altered by CR. The adipocyte stem cell population remained unchanged; however, t10-c12 CLA reduced and CR elevated the proportion of immature adipocytes in obese mice, suggesting differential effects on adipocyte maturation. t10-c12 CLA reduced apoptosis (activated caspase-3) in both obese and lean mice but did not alter autophagy (LC3II/LC3I). Nuclear Tbx-1, a marker of metabolically active beige adipocytes, was greater in the adipose of t10-c12 CLA-fed animals. Thus, weight loss achieved via t10-c12 CLA primarily involves fat loss and more cells with Tbx-1 localized to the nucleus, while CR operates through a mechanism that reduces both lean and fat mass and blocks adipocyte differentiation.

Soy PC liposomes as CLA carriers for food applications: Preparation and physicochemical characterization

Soy phosphatidylcholine (PC) liposomes added with conjugated linoleic acid isomers, (CLA, 9c, 11t, and 10t, 12c) at two PC/CLA ratios, 2:0.4 and 2:1, were prepared by ethanolic injection, and followed during 30 days of storage. These systems were investigated in encapsulation efficiency and fatty acid composition by gas chromatography, size by dynamic light scattering, morphology by TEM images, and membrane fluidity by electron paramagnetic resonance (EPR). Both type of formulations showed highly significant stability and protective effect on CLA isomers with encapsulation efficiencies over 80% during storage. Liposome sizes increased at increasing CLA content. TEM showed evidence of oligolamellar vesicles formation. Regarding membrane fluidity, two behaviors were distinguished in the bilayer: CLA at both formulations disordered the outer membrane zone increasing its fluidity, but the formulation with higher CLA content caused a decreased fluidity near the center of the membrane. The method is safe and easily scalable, and formulations are suitable for future applications in food industry.

Modification of fatty acid selectivity of Candida antarctica lipase A by error-prone PCR

ObjectiveTo generate Candida antarctica lipase A (CAL-A) mutants with modified fatty acid selectivities and improved lipolytic activities using error-prone PCR (epPCR).ResultsA Candida antarctica lipase A mutant was obtained in three rounds of epPCR. This mutant showed a 14 times higher ability to hydrolyze triacylglycerols containing conjugated linoleic acids, and was 12 and 14 times more selective towards cis-9, trans-11 and trans-10, cis-12 isomers respectively, compared to native lipase. Lipolytic activities towards fatty acid esters were markedly improved, in particular towards butyric, lauric, stearic and palmitic esters.ConclusionDirected molecular evolution is an efficient method to generate lipases with desirable selectivity towards CLA isomers and improved lipolytic activities towards esters of fatty acids.

Selective Enrichment of Conjugated Linoleic Acid Isomers in Their Mixtures Using Combined Chemical and Enzymatic Methods

AbstractThe aim of this study was to selectively enrich t10,c12‐conjugated linoleic acid (t10,c12‐CLA) and c9,t11‐CLA in commercial CLA mixtures using a combination of urea crystallization and lipase‐catalyzed esterification. The objective of the urea fractionation is to remove saturated and monounsaturated fatty acids (FA) from the CLA mixtures. CLA‐enriched free FA (FFA) mixtures containing 53.8 wt% t10,c12‐CLA and 39.1 wt% c9,t11‐CLA were produced from the CLA mixtures containing ~34 wt% each of the two CLA isomers by a urea crystallization using methanol and the urea‐to‐FA weight ratio of 2.5:1. The CLA‐enriched FFA mixtures were partially esterified with dodecan‐1‐ol in a recirculating packed‐bed reactor using an immobilized lipase from Candida rugosa to further enrich the t10,c12‐CLA and c9,t11‐CLA in an FFA fraction and an FA dodecyl ester fraction, respectively, under the optimal conditions, i.e., temperature, 20 °C; FA‐to‐dodecan‐1‐ol molar ratio, 1:1; water content, 2 wt% of total substrates; residence time, 5 min; and reaction time, 24 h (for t10,c12‐CLA enrichment) and 12 h (for c9,t11‐CLA enrichment). After the reaction, an FFA fraction with 72.6 wt% t10,c12‐CLA was obtained. Another FFA fraction with 62.0 wt% c9,t11‐CLA was recovered after the saponification of the FA dodecyl ester fraction. The yields of t10,c12‐CLA and c9,t11‐CLA in the FFA fractions were 43.6 and 21.5 wt%, respectively, based on their initial weights in the CLA mixtures.

Conjugated linoleic acid content and fatty acids profile of milk from grazing dairy cows in southern Chile fed varying amounts of concentrate

ABSTRACTConjugated linoleic acids (CLAs) are fatty acids found in bovine milk which possess benefits for human health. This study aimed to compare fatty acid profiles, particularly CLA, of milk from grazing cows from south Chile receiving varying levels of concentrate. The study was conducted during spring of 2012 in two dairies from southern Chile. Dairy A was under low grazing intensity with high levels of concentrate (6–8 kg/cow/day); Dairy B combined low levels of concentrate (1–2 kg/cow/day) with more intensive grazing activity. Milk and blood samples were collected from 15 cows at each dairy at 30 days postpartum. Milk was analysed for fatty acid profiles, and blood for beta-hydroxybutyrate. Body condition score, parity, and daily milk yields were recorded. Pasture and concentrates were sampled for nutritional analysis. The proportion of CLA isomers in milk was 0.91% and 1.66% for Dairy A and Dairy B, respectively (p < .05). Dairy B had a lower ratio of saturated to unsaturated fatty acid and higher levels of omega-3 fatty acids than Dairy A. In conclusion, cows with increased grazing and low concentrate presented higher levels of CLA and omega-3 fatty acids than cows with less grazing and greater concentrate.

Fatty Acids of CLA-Enriched Egg Yolks Can Induce Transcriptional Activation of Peroxisome Proliferator-Activated Receptors in MCF-7 Breast Cancer Cells.

In our previous study, we showed that fatty acids from CLA-enriched egg yolks (EFA-CLA) reduced the proliferation of breast cancer cells; however, the molecular mechanisms of their action remain unknown. In the current study, we used MCF-7 breast cancer cell line to determine the effect of EFA-CLA, as potential ligands for peroxisome proliferator-activated receptors (PPARs), on identified in silico PPAR-responsive genes: BCAR3, TCF20, WT1, ZNF621, and THRB (transcript TRβ2). Our results showed that EFA-CLA act as PPAR ligands with agonistic activity for all PPAR isoforms, with the highest specificity towards PPARγ. In conclusion, we propose that EFA-CLA-mediated regulation of PPAR-responsive genes is most likely facilitated by cis9,trans11CLA isomer incorporated in egg yolk. Notably, EFA-CLA activated PPAR more efficiently than nonenriched FA as well as synthetic CLA isomers. We also propose that this regulation, at least in part, can be responsible for the observed reduction in the proliferation of MCF-7 cells treated with EFA-CLA.

Enhanced stability of emulsions treated by Ultra-High Pressure Homogenization for delivering conjugated linoleic acid in Caco-2 cells

Using novel technologies which offer higher protection and release of bioactive compounds is a current challenge in the food industry. Ultra-High-Pressure Homogenization (UHPH) is an emerging technology that produces physico-chemical and microbiological stable emulsions. The ability of oil-in-water emulsions stabilized by soy protein isolates (4%) to deliver conjugated linoleic acid (CLA, 6%), was studied. Emulsions were produced by UHPH at 200 MPa and by conventional homogenization (CH) at 15 MPa. For another batch of CH emulsions, a heat treatment was also conducted applying high-temperature-short-time conditions (72 °C for 20 s; CH-HTST). The physico-chemical properties of the emulsions were determined, as well as microbial, physical, and oxidative stability. The emulsions were subjected to in vitro digestion, and tested on absorptive Caco-2 cells. The presence of CLA isomers was followed throughout the process. When comparing similar formulations, UHPH emulsions showed smaller particle size and a homogeneous microstructure than emulsions prepared by CH or CH-HTST. Moreover, UHPH produced a sterile emulsion and showed better physical stability during storage compared to other treatments, maintaining an optimal oxidative stability until 3 months. After in vitro digestion and delivery in Caco-2 cells, similar percentages of bioavailability of CLA were found for all the emulsion treatments. The study has gone towards enhancing oil-in-water emulsions by using UHPH technology for delivering conjugated linoleic acid in functional foods.

Fatty acid extract from CLA-enriched egg yolks can mediate transcriptome reprogramming of MCF-7 cancer cells to prevent their growth and proliferation.

BackgroundOur previous study showed that fatty acids extract obtained from CLA-enriched egg yolks (EFA-CLA) suppressed the viability of MCF-7 cancer cell line more effectively than extract from non-enriched egg yolks (EFA). In this study, we analysed the effect of EFA-CLA and EFA on transcriptome profile of MCF-7 cells by applying the whole Human Genome Microarray technology.ResultsWe found that EFA-CLA and EFA treated cells differentially regulated genes involved in cancer development and progression. EFA-CLA, compared to EFA, positively increased the mRNA expression of TSC2 and PTEN tumor suppressors as well as decreased the expression of NOTCH1, AGPS, GNA12, STAT3, UCP2, HIGD2A, HIF1A, PPKAR1A oncogenes.ConclusionsWe show for the first time that EFA-CLA can regulate genes engaged in AKT/mTOR pathway and inhibiting cell cycle progression. The observed results are most likely achieved by the combined effect of both: incorporated CLA isomers and other fatty acids in eggs organically modified through hens’ diet. Our results suggest that CLA-enriched eggs could be easily available food products with a potential of a cancer chemopreventive agent.Electronic supplementary materialThe online version of this article (doi:10.1186/s12263-016-0537-z) contains supplementary material, which is available to authorized users.

Trans10, cis12 conjugated linoleic acid inhibits 3T3-L1 adipocyte adipogenesis by elevating β-catenin levels

BackgroundTrans-10, cis-12 (t10-c12) CLA treatment reduces lipid accumulation in differentiating mouse and human adipocytes, and decreases fat mass in mice, yet the mechanism of action remains unknown. ObjectiveThis study investigated the effect of the cis-9, trans-11 (c9-t11) and t10-c12 CLA isomers on the Wnt/β-catenin pathway, which has been reported to inhibit adipogenesis by down-regulating PPARγ. ResultsWe observed that t10-c12 CLA treatment of 3T3-L1 adipocytes increases the levels of β-catenin and Ser-675 phosphorylated β-catenin due to inhibition of its degradation. These changes in β-catenin were not linked to either the Wnt/β-catenin agonist Wnt10b or other upstream effectors such as SFRP-5. Paradoxically, the presence of higher amounts of β-catenin did not elevate cyclin D1 levels, which is recognized as a critical target gene. Neither of the CLA isomers affected the localization of β-catenin in the cytosol and nucleus as determined by immunofluorescence microscopy. However, subcellular fractionation suggested the level of cytosolic β-catenin was reduced in t10-c12 CLA treated cells. Immunoprecipitation revealed that t10-c12 CLA increased the interaction of β-catenin and PPARγ. Conclusionst10-c12-CLA inhibits adipocyte differentiation by increasing β-catenin stability in 3T3-L1 adipocytes, thus enhancing sequestration of PPARγ in an inactive complex, which prevents progression of adipogenesis.

CLA Isomer t10, c12 Induce Oxidation and Apoptosis in 3t3 Adipocyte Cells in a Similar Effect as Omega-3 Linolenic Acid and DHA

CLA Isomer t10, c12 Induce Oxidation and Apoptosis in 3t3 Adipocyte Cells in a Similar Effect as Omega-3 Linolenic Acid and DHA

Vegetable protein isolate-stabilized emulsions for enhanced delivery of conjugated linoleic acid in Caco-2 cells

Developing edible delivery systems which offer higher protection and release of bioactive constituents is a current challenge in the food industry. The ability of oil-in-water emulsions (20% oil) stabilized by soy or pea protein isolates (4%) to deliver conjugated linoleic acid (CLA, 6%), was studied. The emulsions were prepared by conventional homogenization (550 bar) using one or five homogenization passes. The physicochemical properties of the emulsions were determined, as well as loading capacity and oxidative stability. The emulsions were subjected to in vitro digestion, and tested on absorptive Caco-2 cells. The presence of CLA isomers was followed throughout the process. When comparing similar treatments, soy protein isolate emulsions showed smaller particle size distributions than emulsions prepared with pea protein isolates. Emulsions containing soy proteins showed preferential adsorption of the α′ subunit of conglycinin and the A1, A2, A4 subunits of glycinin on the oil droplets. All emulsions protected the encapsulated CLA better than the non-emulsified control in which CLA was oxidized during storage, as well as after in vitro digestion and delivery in Caco-2 cells. Similar percentages of bioaccessibility and bioavailability of CLA were found for all the emulsion treatments. The results obtained here open new prospects for using oil-in-water emulsions as structured emulsion-based delivery systems to be used in functional foods containing CLA with health enhancing properties.