Conjugated Linolenic Acid (CLnA) vs Conjugated Linoleic Acid (CLA): A Comprehensive Review of Potential Advantages in Molecular Characteristics, Health Benefits, and Production Techniques

Conjugated linoleic acid (CLA) has been extensively characterized due to its many biological activities and health benefits, but conjugated linolenic acid (CLnA) is still not well understood. However, CLnA has shown to be more effective than CLA as a potential functional food ingredient. Current research has not thoroughly investigated the differences and advantages between CLnA and CLA. This article compares CLnA and CLA based on molecular characteristics, including structural, chemical, and metabolic characteristics. Then, the in vivo research evidence of CLnA on various health benefits is comprehensively reviewed and compared with CLA in terms of effectiveness and mechanism. Furthermore, the potential of CLnA in production technology and product protection is analyzed. In general, CLnA and CLA have similar physicochemical properties of conjugated molecules and share many similarities in regulation effects and pathways of various health benefits as well as in the production methods. However, their specific properties, regulatory capabilities, and unique mechanisms are different. The superior potential of CLnA must be specified according to the practical application patterns of isomers. Future research should focus more on the advantageous characteristics of different isomers, especially the effectiveness and safety in clinical applications in order to truly exert the potential value of CLnA.

Pomegranate Seed Oil as a Source of Conjugated Linolenic Acid (CLnA) Has No Effect on Atherosclerosis Development but Improves Lipid Profile and Affects the Expression of Lipid Metabolism Genes in apoE/LDLR-/- Mice

The aim of this study was to evaluate the anti-atherosclerotic effect of pomegranate seed oil as a source of conjugated linolenic acid (CLnA) (cis-9,trans-11,cis-13; punicic acid) compared to linolenic acid (LnA) and conjugated linoleic acid (CLA) (cis-9,trans-11) in apoE/LDLR^-/- mice. In the LONG experiment, 10-week old mice were fed for the 18 weeks. In the SHORT experiment, 18-week old mice were fed for the 10 weeks. Diets were supplied with seed oils equivalent to an amount of 0.5% of studied fatty acids. In the SHORT experiment, plasma TCh and LDL+VLDL cholesterol levels were significantly decreased in animals fed CLnA and CLA compared to the Control. The expression of PPARα in liver was four-fold increased in CLnA group in the SHORT experiment, and as a consequence the expression of its target gene ACO was three-fold increased, whereas the liver's expression of SREBP-1 and FAS were decreased in CLnA mice only in the LONG experiment. Punicic acid and CLA isomers were determined in the adipose tissue and liver in animals receiving pomegranate seed oil. In both experiments, there were no effects on the area of atherosclerotic plaque in aortic roots. However, in the SHORT experiment, the area of atherosclerosis in the entire aorta in the CLA group compared to CLnA and LnA was significantly decreased. In conclusion, CLnA improved the lipid profile and affected the lipid metabolism gene expression, but did not have the impact on the development of atherosclerotic plaque in apoE/LDLR^-/- mice.

Pomegranate Oil’s Potential as an Anti-Obesity Ingredient

In recent years, pomegranate oil has obtained more attention due to its content of conjugated linolenic acids and possible application in the prevention of many diseases. The purpose of this work was to evaluate the potential ability of pomegranate oil to modulate obesity-related metabolism and immune response using in vitro models. In this regard, pomegranate oil was characterized in terms of fatty acids profile, tocopherols and phytosterols, and antioxidant capacity. After evaluation of the safety profile, pomegranate oil’s capacity to modulate obesity-related metabolism was evaluated through adipolysis and adipokines secretion quantification in 3T3-L1 differentiated adipocytes and hepatic lipid accumulation assay in Hep G2 hepatocytes. The immunomodulatory activity was evaluated in Caco-2 cells by quantification of pro-inflammatory cytokines IL-6, IL-8, and TNF-α. This oil showed high antioxidant capacity and was mainly composed of conjugated fatty acid, namely punicic acid. Its chemical composition was responsible for its capacity to reduce the lipid accumulation in Hep G2 cells and 3T3-L1 differentiated adipocytes. In short, pomegranate oil shows great potential for the development of functional foods and nutraceuticals targeting obesity.

Lipidomic Profile and Enzymes Activity in Hepatic Microsomes of Rats in Physiological and Pathological Conditions

Among the risk factors affecting the development of cancer, nutritional factors occupy a significant place. Pomegranate seed oil (PSO) and bitter melon extract (BME), used for ages in folk medicine, are nowadays used in the prevention of many diseases and as ingredients of dietary supplements. Despite numerous publications on these raw materials or their active substances, their mechanism of action in various pathological states has not been recognized yet, nor has the safety of their simultaneous use been evaluated. The study aimed to assess how dietary supplementation with either PSO, with BME, or both, affects fatty acids’ profiles and their metabolism in hepatic microsomes, as well as the activity of selected microsomal enzymes (COX-2 and CYP1B1). Experimental animals (Sprague-Dawley rats) were divided into eight parallel experimental groups, differing in applied dietary modifications (control, PSO, BME and both PSO and BME) and introduction of chemical carcinogen—7,12-dimethylbenz[a]nthracene. Obtained results indicated the pronounced effect of the cancerous process on lipid metabolism and demonstrated the antagonistic effect of applied dietary supplements on the content of individual fatty acids and the activity of CYP1B1 and COX-2. The applied broad analytical approach and chemometric data analysis confirmed that raw materials, for which potential cancer prevention has been previously demonstrated, may differ in effects depending on the coexisting pathological state.

Punicic acid ameliorates obesity and liver steatosis by regulating gut microbiota composition in mice

This study aimed to elucidate the effect of punicic acid (PUA, cis9,trans11,cis13-18 : 3) on obesity and liver steatosis in mice induced by high-fat diet (HFD), and to explore the possible mechanism. Mice were fed with either a HFD or a control diet for 8 weeks. Half of HFD-mice received daily supplementation of PUA. Supplementation with PUA ameliorated the liver steatosis and obesity in mice fed by HFD, as demonstrated by the decreased hepatic triglyceride accumulation, body weight gain and fat weight. A HFD increased the ratio of Firmicutes to Bacteroidetes, whereas supplementation with PUA effectively restored it. PUA supplementation counteracted the upregulation in family Desulfovibrionaceae and Helicobacteraceae, and the downregulation in Muribaculaceae and Bacteroidaceae induced by HFD. Correspondingly, the family of Desulfovibrionaceae was positively related, whereas Muribaculaceae was negatively related to the amount of epididymal and perirenal fat, and the level of liver triglyceride and total cholesterol. The family Helicobacteraceae was also positively related to the amount of epididymal and perirenal fat. Moreover, PUA supplementation counteracted the increase in the population of Anaerotruncus, Faecalibaculim, Mucispirillum, and the decrease in the population of Lactobacillus, Roseburia, Oscillibacter at the genus level induced by HFD. These results demonstrated that PUA can at least in part ameliorate obesity and liver steatosis in mice induced by HFD by regulating gut microbiota composition.

Pomegranate seed oil and bitter melon extract supplemented in diet influence the lipid profile and intensity of peroxidation in livers of SPRD rats exposed to a chemical carcinogen

Despite promising health effects of pomegranate seed oil (PSO) and bitter melon extract (BM) used for centuries as food and traditional medicine, neither mechanism of action nor safety has been fully recognized. This study aimed to evaluate the influence of diet supplementation with PSO and BM on fatty acid, conjugated fatty acid and cholesterol content in rat' livers, since liver is crucial for lipid metabolism. Oxidation indicators (malondialdehyde, oxysterols and tocopherols) were also determined. Lipid profiles did not reveal the presence of punicic acid, while other conjugated dienes and trienes, including rumenic acid, were determined. Both supplementation and exposition to carcinogen significantly increased cholesterol and reduced selected oxysterols levels, simultaneously increasing malondialdehyde content in animals suffering from cancer. Impact of PSO and BM on oxidative status varied depending on carcinogen exposure and coexisting neoplastic process, which is important, due to the growing interest in their use in prevention and therapy of various diseases, including cancer.

Liver and serum lipids in Wistar rats fed a novel structured lipid containing conjugated linoleic acid and conjugated linolenic acid

Conjugated linoleic acid (CLA) and conjugated linolenic acid (CLnA) have been known to have several health-promoting effects. The aim of this study was to introduce a novel structured lipid (SL) including both CLA and CLnA (cis9, trans11, cis13-18:3, punicic acid) into one triacylglycerol (TAG) molecule through enzymatic interesterification and investigate its effect on body weight, liver and serum lipids in Wistar rats. CLA oil, pomegranate seed oil (as a rich source of CLnA) and soybean oil (as a negative control) were applied as other experimental oils. The rats were fed the oils at 1500 mg/kg body weight per day via oral gavage for 45 days. Gas chromatography analysis showed that SL included CLnA and CLA in roughly equal concentrations. The in vivo study revealed that SL had the greatest effect on the reduction in liver lipid weight (4.65 g/100g of liver) and liver TAG (13.28 mg/g) compared to soybean oil (8.7 g/100g and 18.8 mg/g, respectively). High density lipoprotein cholesterol (HDL-C) in the serum of rats which were fed CLA oil significantly (p < 0.05) increased (from 0.95 to 1.14 mmol/l). Pomegranate seed oil reduced low density lipoprotein cholesterol (LDL-C) and total cholesterol (about 40% and 24% reduction, respectively). A remarkable TAG reduction (p < 0.05) was observed in all treated rats.

Dietary wild bitter gourd displays selective androgen receptor modulator like activity and improves the muscle decline of orchidectomized mice

Loss of skeletal muscle mass and strength is often associated with disability and poor quality of life. Selective Androgen Receptor Modulators (SARMs) are under development as potential treatment. This study aims at examining the potential of wild bitter gourd (BG) as a SARM and its effects on the muscle decline induced by orchiectomy. In the cell-based androgen receptor (AR) transactivation assay, the BGP extract showed weak agonistic and antagonistic activities, resembling those of some SARMs. Male C57BL/6J mice were sham-operated (Sham group) or castrated (Cast groups) and fed a modified AIN-93G high sucrose diet supplemented without (Cast group) or with 5% lyophilized BG powder (Cast + BGP) or with testosterone propionate (7 mg TP per kg diet, Cast + TP) for 23 weeks. In contrast to the Cast + TP group, the BGP supplementation did not affect the serum testosterone concentration, and prostate and seminal vesicle mass. Both TP and BGP supplementation increased the weight of androgen responsive muscles, bulbocavernosus (BC) and levator ani (LA) (p < 0.05). The grip strength and the performance on a rotarod of the Cast + BGP group were comparable to those of the Cast + TP group (p > 0.05). The number of succinate dehydrogenase (SDH)-positive fibers of the Cast + BGP group was not significantly different from that of the Sham and Cast + TP groups (p > 0.05). The BGP supplementation up-regulated the Pgc1α, Ucp2 or Ucp3 gene expressions in skeletal muscles of castrated mice (p < 0.05). BGP showed some characteristics of the SARM and might improve skeletal muscle function through the up-regulation of mitochondrial biogenic genes and oxidative capacity, and ameliorated the castration-induced decline of skeletal muscle function in mice.

Probiotics in human health and disease: from nutribiotics to pharmabiotics

Probiotics are the most useful tools for balancing the gut microbiota and thereby influencing human health and disease. Probiotics have a range of effects, from those on nutritional status to medical conditions throughout the body from the gut to non-intestinal body sites such as the brain and skin. Research interest in probiotics with nutritive claims (categorized as nutribiotics) has evolved into interest in therapeutic and pharmacological probiotics with health claims (pharmabiotics). The concept of pharmabiotics emerged only two decades ago, and the new categorization of probiotics to nutribiotics and pharmabiotics was recently suggested, which are under the different regulation depending on that they are food or drug. Information of the gut microbiome has been continuously accumulating, which will make possible the gut microbiome-based healthcare in the future, when nutribiotics show potential for maintaining health while pharmabiotics are effective therapeutic tools for human diseases. This review describes the current understanding in the conceptualization and classification of probiotics. Here, we reviewed probiotics as nutribiotics with nutritional functions and pharmabiotics with pharmaceutic functions in different diseases.

Punicic acid: A potential compound of pomegranate seed oil in Type 2 diabetes mellitus management

Diabetes is one of the most prevalent diseases in the worldwide. Type 2 diabetes mellitus (T2DM), the most common form of the disease, has become a serious threat to public health and is a growing burden on global economies. Due to the unexpected adverse effects of antidiabetic medicines, the use of nutraceuticals as a complementary therapy has drawn extensive attention by investigators. In this issue, a novel nutraceutical, Punicic acid (PA)-the main ingredient of pomegranate seed oil (PSO) that has potential therapeutic effects in T2DM-has been investigated. PA is a peroxisome proliferator-activated receptor gamma agonist, and unlike synthetic ligands, such as thiazolidinediones, it has no side effects. PA exerts antidiabetic effects via various mechanisms, such as reducing inflammatory cytokines, modulating glucose homeostasis, and antioxidant properties. In this review, we discussed the potential therapeutic effects of PSO and PA and represented the related mechanisms involved in the management of T2DM.

Punicic acid: A striking health substance to combat metabolic syndromes in humans

Punicic acid, a bioactive compound of pomegranate seed oil has gained wide attention for their therapeutic potential. Different studies conducted on animal and human models have revealed that punicic acid is very effective against various chronic diseases. Substantial laboratory works has been carried out to elaborate punicic acid effectiveness and mechanism of action in animals. The intention of this review article is to explore the facts about the clinical trials of punicic acid and to discuss different future strategies that can be employed to use it in human clinical trials. Although punicic acid may represent a novel therapeutic unconventional approach for some disorders, still further experimental studies are required to demonstrate its effects in human beings.

Pomegranate seed oil influences the fatty acids profile and reduces the activity of desaturases in livers of Sprague-Dawley rats

The aim of our study was to compare the influence of diet supplementation with pomegranate seed oil - as conjugated linolenic acids (CLnA) source, or conjugated linoleic acids (CLA) and to examine the mechanism of their activity. The content of fatty acids, levels of biomarkers of lipids' oxidation and the activity of key enzymes catalyzing lipids metabolism were measured. Obtained results revealed that conjugated fatty acids significantly decrease the activity of Δ5-desaturase (p=0.0001) and Δ6-desaturase (p=0.0008) and pomegranate seed oil reduces their activity in the most potent way. We confirmed that diet supplementation with pomegranate seed oil - a rich source of punicic acid leads to the increase of cis-9, trans-11 CLA content in livers (p=0.0003). Lack of side effects and beneficial influence on desaturases activity and fatty acids profile claim pomegranate seed oil to become interesting alternative for CLA as functional food.

Conjugated fatty acid-rich oil from Gynostrmma pentaphyllum seed can ameliorate lipid and glucose metabolism in type 2 diabetes mellitus mice

Gynostrmma pentaphyllumseed oil (GPSO), extracted fromG. pentaphyllumseeds, is rich in conjugated linolenic acid, which is a special fatty acid consisting ofcis-9,trans-11,trans-13 isomers.

A conjugated fatty acid present at high levels in bitter melon seed favorably affects lipid metabolism in hepatocytes by increasing NAD(+)/NADH ratio and activating PPARα, AMPK and SIRT1 signaling pathway

α-Eleostearic acid (α-ESA), or the cis-9, trans-11, trans-13 isomer of conjugated linolenic acid, is a special fatty acid present at high levels in bitter melon seed oil. The aim of this study was to examine the effect of α-ESA on hepatic lipid metabolism. Using H4IIEC3 hepatoma cell line, we showed that α-ESA significantly lowered intracellular triglyceride accumulation compared to α-linolenic acid (LN), used as a fatty acid control, in a dose- and time-dependent manner. The effects of α-ESA on enzyme activities and mRNA profiles in H4IIEC3 cells suggested that enhanced fatty acid oxidation and lowered lipogenesis were involved in α-ESA-mediated triglyceride lowering effects. In addition, α-ESA triggered AMP-activated protein kinase (AMPK) activation without altering sirtuin 1 (SIRT1) protein levels. When cells were treated with vehicle control (VC), LN alone (LN; 100μmol/L) or in combination with α-ESA (LN+α-ESA; 75+25μmol/L) for 24h, acetylation of forkhead box protein O1 was decreased, while the NAD(+)/NADH ratio, mRNA levels of NAMPT and PTGR1 and enzyme activity of nicotinamide phosphoribosyltransferase were increased by LN+α-ESA treatment compared to treatment with LN alone, suggesting that α-ESA activates SIRT1 by increasing NAD(+) synthesis and NAD(P)H consumption. The antisteatosis effect of α-ESA was confirmed in mice treated with a high-sucrose diet supplemented with 1% α-ESA for 5weeks. We conclude that α-ESA favorably affects hepatic lipid metabolism by increasing cellular NAD(+)/NADH ratio and activating PPARα, AMPK and SIRT1 signaling pathways.

Incorporation and effects of punicic acid on muscle and adipose tissues of rats

BACKGROUND

This study evaluated the effect of pomegranate seed oil (PSO) supplementation, rich in punicic acid (55 %/C18:3-9c,11 t,13c/CLNA), on the lipid profile and on the biochemical and oxidative parameters in the gastrocnemius muscle and adipose tissues of healthy rats. Linseed oil (LO), rich in linolenic acid (52 %/C18:3-9c12c15c/LNA) was used for comparison.

METHODS

Male Wistar rats (n = 56) were distributed in seven groups: control (water); LNA 1 %, 2 % and 4 % (treated with LO); CLNA 1 %, 2 % and 4 % (treated with PSO), po for 40 days. The percentages were compared to the daily feed intake. Fatty acid profile were performed by gas chromatography, antioxidant enzymes activity by spectrophotometer and the adipocytes were isolated by collagenase tissue digestion. Analysis of variance (ANOVA) was applied to check for differences between the groups (control, LNAs and CLNAs) and principal component analysis (PCA) was used to project the groups in the factor-place (PC1 vs PC2) based on the biochemical responses assessed in the study.

RESULTS

The fatty acids profile of tissues showed that the LNA percentages were higher in the animals that were fed LO. However, PA was only detected in the adipose tissues. Conjugated linoleic acid (CLA) was present in all the tissues of the animals supplemented with PSO, in a dose dependent manner, and 9c11t-CLA was the predominant isomer. Nevertheless there were no changes in the total weight gain of the animals, the weights of the tissues, and the oxidative stress parameters in the muscle. In addition, there was an increase in the size of the epididymal fat cells in the groups treated with PSO. Principal component analysis (PCA) showed that the CLNAs groups were arranged separately with a cumulative variance of 68.47 %.

CONCLUSIONS

The results show that PSO can be used as a source of CLAs but that it does not cause changes in body modulation and does not interfere in the antioxidant activity of healthy rats.

Health Benefits of Punicic Acid: A Review

Punicic acid (PA) is a polyunsaturated fatty acid (18:3 n-5), which is classified as a conjugated linolenic acid. PA is also referred as a "super CLnA" whose effect is even more potent than that of an ordinary CLnA. It is found mainly in the seeds of pomegranate fruit (Punica granatum) and Trichoxanthes kirilowii and some other minor sources. It possesses a wide array of biological properties including antidiabetic, antiobesity, antiproliferative, and anticarcinogenic activity against various forms of cancer. In spite of this, PA has not been explored as a nutraceutical or as an ingredient of food products which can be aimed at specific consumer target groups. This review details the various health-beneficial properties of PA and explores the possibilities of its utilization as an active ingredient in various food products.

Modulation of peroxisome proliferator-activated receptor gamma (PPAR γ) by conjugated fatty acid in obesity and inflammatory bowel disease

Conjugated fatty acids including conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) have drawn significant attention for their variety of biologically beneficial effects. Evidence suggested that CLA and CLNA could play physiological roles by regulating the expression and activity of PPAR γ. This review summarizes the current understanding of evidence of the role of CLA (cis-9,trans-11 CLA and trans-10,cis-12 CLA) and CLNA (punicic acid and α-eleostearic acid) in modulating the expression or activity of PPAR γ that could in turn be employed as complementary treatment for obesity and inflammatory bowel disease.

Implication of fermentable carbohydrates targeting the gut microbiota on conjugated linoleic acid production in high-fat-fed mice

In vitro experiments have shown that isolated human gut bacteria are able to metabolise PUFA into conjugated PUFA like conjugated linoleic acids (CLA). The hypothesis of the present paper was that high-fat (HF) diet feeding and supplementation with fermentable carbohydrates that have prebiotic properties modulate the in vivo production of CLA by the mouse gut microbiota. Mice were treated for 4 weeks as follows: control (CT) groups were fed a standard diet; HF groups were fed a HF diet rich in linoleic acid (18 : 2n-6); the third groups were fed with the HF diet supplemented with either inulin-type fructans (HF-ITF) or arabinoxylans (HF-Ax). HF diet feeding increased rumenic acid (cis-9,trans-11-18 : 2 CLA) content both in the caecal and liver tissues compared with the CT groups. ITF supplementation had no major effect compared with the HF diet whereas Ax supplementation increased further rumenic acid (cis-9,trans-11-18 : 2 CLA) in the caecal tissue. These differences between both prebiotics may be linked to the high fat-binding capacity of Ax that provides more substrates for bacterial metabolism and to differential modulation of the gut microbiota (specific increase in Roseburia spp. in HF-Ax v. HF). In conclusion, these experiments supply the proof of concept that the mouse gut microbiota produces CLA in vivo, with consequences on the level of CLA in the caecal and liver tissues. We postulate that the CLA-producing bacteria could be a mediator to consider in the metabolic effects of both HF diet feeding and prebiotic supplementation.

Effect of a high dose of CLA in finishing pig diets on fat deposition and fatty acid composition in intramuscular fat and other fat depots

Sixteen gilts were fed a control (4% of sunflower oil) or an experimental diet (4% conjugated linoleic acid (CLA) oil). CLA had no effect on intramuscular fat (IMF) content neither in longissimus thoracis (LT) nor in semimembranosus (SM) muscles but increased liver weight, reduced perirenal fat and tended to reduce backfat between the last 3th-4th lumbar vertebrae. Despite the fact that 9c,11t and 10t,12c CLA isomers were included in the same proportion in the diet, the 9c,11t and 9c,11c were the isomers more deposited in all tissues. Addition of CLA in the diet affected fatty acid composition in a tissue specific manner, increasing percentages of SFA in all tissues, reducing percentages of MUFA in LT and LT subcutaneous fat, and of PUFA in LT subcutaneous fat, liver and SM. The FA modification by dietary CLA in LT IMF was reflected in the different lipid fractions, SFA and MUFA mainly in the neutral lipid fraction, and PUFA in the polar fraction.

Conjugated linoleic and linolenic acid production kinetics by bifidobacteria differ among strains

There is great interest in conjugated linoleic acid (CLA) and conjugated linolenic acid (CLNA) isomers because of their supposed health-promoting properties. Therefore, the differences in production kinetics of CLA and CLNA isomers from linoleic acid (LA) and α-linolenic acid (α-LNA), respectively, by bifidobacteria were investigated. Laboratory fermentations, supplemented with LA or α-LNA in the fermentation medium, were performed with Bifidobacterium bifidum LMG 10645, Bifidobacterium breve LMG 11040, B. breve LMG 11084, B. breve LMG 11613, B. breve LMG 13194, and Bifidobacterium pseudolongum subsp. pseudolongum LMG 11595. Conversion of LA and α-LNA to CLA and CLNA isomers, respectively, started immediately upon addition of the substrate fatty acids. During the active growth phase, the c9, t11-CLA isomer and the putative c9, t11, c15-CLNA isomer were formed. Further fermentation resulted in a reduction in the concentration of c9, t11-CLA and c9, t11, c15-CLNA and the subsequent production of the t9, t11-CLA isomer and the putative t9, t11, c15-CLNA isomer, respectively. Modelling of the growth and metabolite data indicated differences in production kinetics among the strains. Some strains displayed a high specific conversion of LA and α-LNA despite poor growth, whereas other strains grew well but displayed lower conversion. Production of specific CLA and CLNA isomers by bifidobacteria holds potential for the production of functional foods and could contribute to their probiotic properties.