Dietary effect of pomegranate seed oil on immune function and lipid metabolism in mice

Conjugated linolenic acids and their bioactivities: a review

Conjugated linolenic acid (CLNA) is a mixture of positional and geometric isomers of octadecatrienoic acid (α-linolenic acid, cis9,cis12,cis15-18:3 n-3) found in plant seeds. Three 8,10,12-18:3 isomers and four 9,11,13-18:3 isomers have been reported to occur naturally. CLNA isomers such as punicic acid, α-eleostearic acid and jacaric acid have been attributed to exhibit several health benefits that are largely based on animal and in vitro studies. This review has summarized and updated the evidence regarding the metabolism and bioactivities of CLNA isomers, and comprehensively discussed the recent studies on the effects of anti-carcinogenic, lipid metabolism regulation, anti-inflammatory, anti-obese and antioxidant activities of CLNA isomers. The available results may provide a potential application for CLNA isomers from natural sources, especially edible plant seeds, as effective functional food ingredients and dietary supplements for the above mentioned disease management. Further research, especially human randomized clinical trials, is warranted to investigate the detailed physiological effects, bioactivity and molecular mechanism of CLNA.

Protective effect of pomegranate seed oil against mercuric chloride-induced nephrotoxicity in rat

PURPOSE

Heavy metals such as mercury can induce the generation of free radicals and oxidative stress which are associated with tissue injury. The present study was designed to evaluate the protective effect of pomegranate seed oil against HgCl2-induced nephrotoxicity.

METHODS

Twenty-four W/A adult rats were randomly divided into four groups. Group I received corn oil (1 mL/kg). Group II received HgCl2 (5 mg/kg) for 3 days. Group III and IV received PSO 0.4 mL/kg and 0.8 mL/kg, respectively one hour before HgCl2 administration for 3 days. Blood samples were taken by cardiac puncture and used for the measurement of urea and creatinine concentration. Twenty-hour-hour urine samples were collected to measure protein and glucose. The right kidney was fixed in formalin for histological examination and the left kidney was homogenized for measuring malondialdehyde (MDA) and total sulfhydryl groups.

RESULTS

Significant elevation of serum creatinine and urea levels as well as urine glucose and protein concentrations, a significant decrease in total thiol content and a significant increase in MDA levels in kidney homogenate samples were observed after administration of HgCl2 as compared with control group. PSO pretreatment resulted in a significant decrease in serum creatinine and urea levels as well as urine glucose and protein concentrations when compared with HgCl2 treated (group II). PSO also significantly reversed the HgCl2-induced depletion in thiol content and elevation in MDA content. Histological studies revealed milder kidney lesions in PSO treated groups (groups III and IV) compared to HgCl2 treated group.

CONCLUSION

Our results suggest that PSO has a protective effect against HgCl2-induced nephrotoxicity in rats.

Effect of a Punica granatum enriched diet on immunocompetence in Rhinella marina

Direct ingestion of plant materials has been shown to have immunomodulatory effects on a variety of herbivores. Studies have also shown that compounds ingested indirectly by predators through prey items can affect the general physiology of the ingesting organism. Relatively little data exists, however, concerning the modulation of a predator's immune system via compounds obtained indirectly through prey. In this study, we sought to determine if the immune-stimulating properties of Punica granatum (pomegranate) could be conveyed from a prey organism, Acheta domestica, to a predator, Rhinella marina, through diet specialization. Experimental crickets were fed a diet of agar supplemented with 10 mg/mL of lyophilized, powdered, whole pomegranate while control crickets were fed unadulterated agar. Experimental toads consumed a diet consisting of crickets fed the pomegranate-enriched diet, while control toads consumed a diet consisting of crickets fed the standard agar diet. Blood samples were taken weekly and leukocyte profiles and neutrophil phagocytic activity were determined for all toads over an 8-week period. Complement activity was measured at 6 weeks. Toads fed the pomegranate-enriched diet showed altered leukocyte profiles as evidenced by an increase in circulating eosinophil number and a decrease in the number of circulating lymphocytes, monocytes, and basophils as compared to controls, indicating an immunomodulatory effect of the pomegranate-enhanced diet. These results suggest that pomegranate-derived immunomodulatory compounds can be transferred from prey to predator, and suggests that the flora in the environment where insectivores forage could have a significant effect on the physiology of the animal.

Effects of pomegranate seed oil on glucose and lipid metabolism-related organs in rats fed an obesogenic diet

Studies conducted in mice have revealed positive effects of punicic acid (PUA). The aim of this study was to analyze the effects of PUA on fat accumulation and glycemic control in rats fed an obesogenic diet. Rats were randomly divided into two groups: control group and PUA group (diet supplemented with 0.5% PUA). No changes were observed in adipose tissue weights. The glucose tolerance test showed that the glycemic value in the PUA group had decreased significantly at the final time (120 min) (-19.3%), as had fructosamine levels (-11.1%). However, homeostasis model assessment (HOMA-IR) showed that insulin resistance did not improve. No changes were observed in the liver, skeletal muscle composition, or peroxisome proliferator-activated receptors (PPARs) activation. Low levels (mg/g tissue) of PUA (0.04 ± 0.01 in both tissues) and higher levels of cis-9,trans-11 conjugated linoleic acid (0.31 ± 0.08 in liver, 0.52 ± 0.11 in muscle) were found. PUA supplementation induced hypoplasia (-16.1%) due to the antiproliferative effect on hepatocytes. In conclusion, dietary supplementation of 0.5% PUA did not lead to decreased fat accumulation in adipose tissue, liver, or skeletal muscle, or to improved glycemic control. The hypoplasia induced in liver is a negative effect that should be considered before proposing PUA as a functional ingredient.

Optimization of ultrasonic-assisted extraction of pomegranate (Punica granatum L.) seed oil

The effectiveness of ultrasonic-assisted extraction (UAE) of pomegranate seed oil (PSO) was evaluated using a variety of solvents. Petroleum ether was the most effective for oil extraction, followed by n-hexane, ethyl acetate, diethyl ether, acetone, and isopropanol. Several variables, such as ultrasonic power, extraction temperature, extraction time, and the ratio of solvent volume and seed weight (S/S ratio) were studied for optimization using response surface methodology (RSM). The highest oil yield, 25.11% (w/w), was obtained using petroleum ether under optimal conditions for ultrasonic power, extraction temperature, extraction time, and S/S ratio at 140 W, 40 °C, 36 min, and 10 ml/g, respectively. The PSO yield extracted by UAE was significantly higher than by using Soxhlet extraction (SE; 20.50%) and supercriti cal fluid extraction (SFE; 15.72%). The fatty acid compositions were significantly different among the PSO extracted by Soxhlet extraction, SFE, and UAE, with punicic acid (>65%) being the most dominant using UAE.

Effect of pomegranate seed oil against gentamicin -induced nephrotoxicity in rat

Gentamicin, an important aminoglycoside, is used to treat many types of bacterial infections, particularly those caused by Gram-negative organisms. It is a nephrotoxic antibiotic, which causes acute tubular necrosis, and its toxicity remains a major problem in clinical use. This study investigates the effect of pomegranate seed oil (PSO) on gentamicin-induced nephrotoxicity in adult male rats. Animals were randomly divided into four groups. Group one was treated with saline (1 ml/kg, i.p.), group 2 received gentamicin 80 mg/kg/day for 6 days and groups 3 and 4 received PSO 0.32 and 0.64 mg/kg/day i.p. respectively, 1 h before gentamicin. Serum urea, creatinine levels, urinary glucose and protein concentrations were evaluated as the markers of acute renal failure. Renal antioxidant indicators such as thiobarbituric acid-reactive substance (TBARS), and total thiol contents, were also determined. A significant elevation of serum creatinine and urea levels as well as urine glucose and protein concentrations were observed in gentamicin treated group. Gentamicin also caused a significant decrease in total thiol content and a significant increase in TBARS levels in kidney homogenate samples. PSO pretreatment resulted in a significant and dose-dependent decrease in serum creatinine and urea levels as well as urine glucose and protein concentrations when compared with gentamicin treated alone. PSO also significantly reversed the gentamicin-induced depletion in total thiol content and elevation in TBARS in kidney homogenate samples. The results of the present study indicate that PSO clearly attenuated gentamicin-induced nephrotoxicity, but elucidation of the mechanism(s) of this protection needs more investigation.

Pomegranate: a fruit that ameliorates metabolic syndrome

Pomegranate is an ancient fruit that is still part of the diet in the Mediterranean area, the Middle East, and India. Health-promoting effects have long been attributed to this fruit. Modern research corroborates the use of pomegranate as a folk remedy for diabetes and metabolic syndrome, and is responsible for a new evaluation of nutritional and pharmaceutical aspects of pomegranate in the general public. In the last decade, industry and agricultural production have been adapted to meet higher market demands for pomegranate. In vivo and in vitro studies have demonstrated that pomegranate exerts hypoglycaemic effects, including increased insulin sensitivity, inhibition of α-glucosidase, and impact on glucose transporter type 4 function, but is also responsible for a reduction of total cholesterol, and the improvement of blood lipid profiles, as well as anti-inflammatory effects through the modulation of peroxisome proliferator-activated receptor pathways. These effects may also explain how pomegranate-derived compounds function in the amelioration of adverse health effects caused by metabolic syndrome. Pomegranate contains polyphenols such as ellagitannins and anthocyanins, as well as phenolic acids, fatty acids and a variety of volatile compounds. Ellagitannins are some of the most prevalent compounds present in pomegranate, and may be responsible for certain benevolent characteristics associated with pomegranate. A brief overview of rising health problems due to obesity will be provided, followed by characterisation of the biological activity, bioavailability, and safety of pomegranate and pomegranate-derived compounds. Although the fruit is consumed in many countries, epidemiological and clinical studies are unavailable. Additional research is necessary to corroborate the promise of current in vivo and in vitro findings.

Uptake of conjugated linolenic acids and conversion to cis-9, trans-11-or trans-9, trans-11-conjugated linoleic acids in Caco-2 cells

Dietary oils containing large amounts of conjugated linolenic acids (CLnA) may be regarded as a source of conjugated linoleic acids (CLA), which have been suspected to bear health-promoting properties. Indeed, CLnA can be converted into CLA in mammals. The objective of the present study was to investigate the uptake of CLnA and their metabolism into CLA in Caco-2 cells, as a validated in vitro model of the intestinal barrier. Caco-2 cells were incubated for 24 h in the presence of either α-eleostearic, β-eleostearic, catalpic or punicic acid. We first observed that Caco-2 cells take these CLnA up at different rates and then convert them but with varying efficiency depending on the structure of the Δ13 double bond. Finally, the distribution of CLnA between neutral lipids (NL) and phospholipids appeared to be linked to their number of trans double bonds: the higher the number, the higher the accumulation in the NL fraction.

Obesity: the preventive role of the pomegranate (Punica granatum)

Obesity represents a rapidly growing threat to the health of populations in an increasing number of countries. Diet intervention has been proposed as one of the strategies for weight loss and weight maintenance. Traditionally, the pomegranate, including its roots, tree bark, fruit juice, leaves, and flowers, has been used to treat some conditions such as diarrhea, hemorrhage, acidosis, and microbial infections. Pomegranate extracts have been found to have strong anti-inflammatory, antioxidant, and even antitumor properties in vivo and in vitro. More recently, positive effects on fat reduction have been shown using the pomegranate and its extracts. Many of the beneficial effects are related to the presence of anthocyanins, tannins, and very high levels of antioxidants, including polyphenols and flavonoids. Many studies have explored the effects of the pomegranate in obesity, and various mechanisms have been proposed as to how these different extracts help in fat reduction. This article provides an overview of the work done addressing the potential benefits of the pomegranate on obesity and assesses the efficacy of intervention by means of the pomegranate and its extracts. Human studies in this field are still limited and need more attention that would help in understanding the preventive and protective roles pomegranate extracts have on obesity.

Effect of pomegranate seed oil on serum TNF-α level in dyslipidemic patients

Pomegranate punicic acid and pomegranate fruit extracts have the potential effects in inhibiting tumour necrosis factor-α (TNF-α) and inflammatory diseases. The aim of this study was to evaluate the effect of pomegranate seed oil (PSO) consumption on serum TNF-α level in dyslipidemic patients. Fifty-one subjects with serum total cholesterol concentration >200 mg/dl and serum triglyceride concentrations >150 mg/dl were randomly assigned into the PSO (n = 25) and placebo (n = 26) groups. Subjects were given 400 mg PSO or placebo capsules twice daily for 4 weeks. Six patients were excluded because of complications or lack of compliance. Serum TNF-α level was measured at baseline and after 4 weeks. Mean (SD) serum concentration of TNF-α decreased from 14.73 ± 5.25 to 13.28 ± 3.79 pg/ml in the PSO group (P = NS). Corresponding values in the placebo group were 12.46 ± 1.67 versus 13.14 ± 1.67 pg/ml (P = NS). In conclusion, administration of PSO in dyslipidemic patients does not affect the serum TNF-α.

The health promoting properties of the conjugated isomers of α-linolenic acid

The bioactive properties of the conjugated linoleic acid (CLA) isomers have long been recognised and are the subject of a number of excellent reviews. However, despite this prominence the CLA isomers are not the only group of naturally occurring dietary conjugated fatty acids which have shown potent bioactivity. In a large number of in vitro and in vivo studies, conjugated α-linolenic acid (CLNA) isomers have displayed potent anti-inflammatory, immunomodulatory, anti-obese and anti-carcinogenic activity, along with the ability to improve biomarkers of cardio-vascular health. CLNA isomers are naturally present in high concentrations in a large variety of seed oils but can also be produced in vitro by strains of lactobacilli and bifidobactena through the activity of the enzyme linoleic acid isomerase on α-linolenic acid. In this review, we will address the possible therapeutic roles that CLNA may play in a number of conditions afflicting Western society and the mechanisms through which this activity is mediated.

Characterization of a potential nutraceutical ingredient: pomegranate (Punica granatum L.) seed oil unsaponifiable fraction

The chemical fingerprinting of the unsaponifiable fraction of different Punica granatum seed oils was performed in order to evaluate their potential as a functional food ingredient. Qualitative and quantitative determinations of tocopherol, aliphatic alcohol (including policosanol), squalene, phytosterols and triterpene contents were performed by GC-MS. A high yield (3.1-4.2%) of unsaponifiable matter was obtained and consistent levels of squalene (up to 800 mg/kg) and policosanol (118-185 mg/kg) were noticed. β-sitosterol (up to 8069 mg/kg) and cycloartenol (5916-7766 mg/kg) were predominant in phytosterol and triterpene fractions, while β- and δ-tocopherol were the most abundant vitamin E forms. Some minor variations were noticed between samples. From the results obtained, it can be suggested that the seed oil of P. granatum can be considered an interesting alimentary source of substances of nutraceutical value involved in the modulation of cholesterol metabolism.

Effect of pomegranate seed oil on hyperlipidaemic subjects: a double-blind placebo-controlled clinical trial

In vitro and in vivo studies have shown that punicic acid, a type of conjugated fatty acid and the main constituent of pomegranate seed oil (PSO), has anti-atherogenic effects. The present study aimed at determining the effect of PSO treatment on serum lipid profiles. This double-blind placebo-controlled randomised clinical trial included fifty-one hyperlipidaemic subjects, diagnosed according to National Cholesterol Education Program definition, and randomly assigned to the PSO and the control groups. The PSO and placebo groups received 400 mg PSO and placebo twice daily, respectively and were followed up for 4 weeks. Serum concentrations of lipids and lipoproteins were measured before and 4 weeks after intervention. Mean concentration of TAG and the TAG:HDL cholesterol (HDL-C) ratio were significantly decreased after 4 weeks in the PSO group as compared with baseline values (2.75 (sd 1.40) v. 3.45 (sd 1.56) mmol/l, P = 0.009 and 5.7 (sd 4.6) v. 7.5 (sd 5.0), P = 0.031, respectively). The treatment effect was statistically significant in the PSO group as compared with controls in diminution of cholesterol:HDL-C ratio (5.4 (sd 1.5) v. 5.9 (sd 1.4), P < 0.05) adjusted for baseline values. We found a mean difference for PSO v. placebo in HDL-C concentration (0.13 v. - 0.02 mmol/l) and cholesterol:HDL-C ratio ( - 0.42 v. 0.01, P < 0.05). Serum cholesterol, LDL cholesterol and glucose concentrations and body composition variables remained unchanged. It is concluded that administration of PSO for 4 weeks in hyperlipidaemic subjects had favourable effects on lipid profiles including TAG and TAG:HDL-C ratio.

Punicic acid a conjugated linolenic acid inhibits TNFalpha-induced neutrophil hyperactivation and protects from experimental colon inflammation in rats

Background

Neutrophils play a major role in inflammation by releasing large amounts of ROS produced by NADPH-oxidase and myeloperoxidase (MPO). The proinflammatory cytokine TNFα primes ROS production through phosphorylation of the NADPH-oxidase subunit p47phox on Ser345. Conventional anti-inflammatory therapies remain partially successful and may have side effects. Therefore, regulation of neutrophil activation by natural dietary components represents an alternative therapeutic strategy in inflammatory diseases such as inflammatory bowel diseases. The aim of this study was to assess the effect of punicic acid, a conjugated linolenic fatty acid from pomegranate seed oil on TNFα-induced neutrophil hyperactivation in vitro and on colon inflammation in vivo.

Methodology and Principal Findings

We analyzed the effect of punicic acid on TNFα-induced neutrophil upregulation of ROS production in vitro and on TNBS-induced rat colon inflammation. Results show that punicic acid inhibited TNFα-induced priming of ROS production in vitro while preserving formyl-methionyl-leucyl-phenylalanine (fMLP)-induced response. This effect was mediated by the inhibition of Ser345-p47phox phosphorylation and upstream kinase p38MAPK. Punicic acid also inhibited fMLP- and TNFα+fMLP-induced MPO extracellular release from neutrophils. In vivo experiments showed that punicic acid and pomegranate seed oil intake decreased neutrophil-activation and ROS/MPO-mediated tissue damage as measured by F2-isoprostane release and protected rats from TNBS-induced colon inflammation.

Conclusions/Significance

These data show that punicic acid exerts a potent anti-inflammatory effect through inhibition of TNFα-induced priming of NADPH oxidase by targeting the p38MAPKinase/Ser345-p47phox-axis and MPO release. This natural dietary compound may provide a novel alternative therapeutic strategy in inflammatory diseases such as inflammatory bowel diseases.

Punica granatum: Heuristic Treatment for Diabetes Mellitus

The current diabetes epidemic is a global concern with readily available effective therapies or preventative measures in demand. One natural product with such potential is the pomegranate (Punica granatum), with hypoglycemic activity noted from its flowers, seeds, and juice in canons of the traditional folk medicines of India. The mechanisms for such effects are largely unknown, though recent research suggests pomegranate flowers and juice may prevent diabetic sequelae via peroxisome proliferator-activated receptor-gamma binding and nitric oxide production. Pomegranate compounds associated with antidiabetic effects include oleanolic, ursolic, and gallic acids. Pomegranate fractions and their active compounds hold potential and are worthy of further investigations as safe and effective medical treatments for diabetes mellitus and its pathological consequences.

Genetically modified rapeseed oil containing cis-9,trans-11,cis-13-octadecatrienoic acid affects body fat mass and lipid metabolism in mice

Punicic acid, one of the conjugated linolenic acid (CLN) isomers, exerts a body-fat reducing effect. Although punicic acid is found in pomegranate and Tricosanthes kirilowii seeds, the amount of this fatty acid is very low in nature. The goal of this study was to produce a transgenic oil containing punicic acid. A cDNA encoding conjugase that converts linoleic acid to punicic acid was isolated from T. kirilowii, and the plant expression vector, pKN-TkFac, was generated. The pKN-TkFac was introduced into Brassica napus by Agrobacterium-mediated transformation. As a result, a genetically modified rapeseed oil (GMRO) containing punicic acid was obtained, although its proportion to the total fatty acids was very low (approximately 2.5%). The effects of feeding GMRO in ICR CD-1 male mice were then examined. Wild-type rapeseed (B. napus) oil (RSO) containing no CLN was used as a control oil. For reference oils, RSO-based blended oils were prepared by mixing with different levels of pomegranate oil (PO), either 2.5% (RSO + PO) or 5.0% (RSO + 2PO) punicic acid. Mice were fed purified diets containing 10% of either RSO, RSO + PO, RSO + 2PO, or GMRO for 4 weeks, and dietary PO dose-dependently reduced perirenal adipose tissue weight with a significant difference between the RSO group and the RSO + 2PO group. GMRO, as compared to RSO, lowered the adipose tissue weight to the levels observed with RSO + 2PO. The liver triglyceride level of the RSO + 2PO and GMRO groups but not that of the RSO + PO group was lower than that of the RSO group. The RSO + 2PO and GMRO groups, but not the RSO + PO group, had increased carnitine-palmitoyltransferase activity in the liver and brown adipose tissue. These results showed that dietary GMRO, even at a dietary punicic acid level as low as 0.25 wt % of diet, reduced body fat mass and altered liver lipid metabolism in mice and was more effective than an equal amount of punicic acid from PO.

Punica granatum (pomegranate) and its potential for prevention and treatment of inflammation and cancer

The last 7 years have seen over seven times as many publications indexed by Medline dealing with pomegranate and Punica granatum than in all the years preceding them. Because of this, and the virtual explosion of interest in pomegranate as a medicinal and nutritional product that has followed, this review is accordingly launched. The pomegranate tree, Punica granatum, especially its fruit, possesses a vast ethnomedical history and represents a phytochemical reservoir of heuristic medicinal value. The tree/fruit can be divided into several anatomical compartments: (1) seed, (2) juice, (3) peel, (4) leaf, (5) flower, (6) bark, and (7) roots, each of which has interesting pharmacologic activity. Juice and peels, for example, possess potent antioxidant properties, while juice, peel and oil are all weakly estrogenic and heuristically of interest for the treatment of menopausal symptoms and sequellae. The use of juice, peel and oil have also been shown to possess anticancer activities, including interference with tumor cell proliferation, cell cycle, invasion and angiogenesis. These may be associated with plant based anti-inflammatory effects, The phytochemistry and pharmacological actions of all Punica granatum components suggest a wide range of clinical applications for the treatment and prevention of cancer, as well as other diseases where chronic inflammation is believed to play an essential etiologic role.

Conjugated linolenic acid is slowly absorbed in rat intestine, but quickly converted to conjugated linoleic acid

We showed previously that alpha-eleostearic acid (alpha-ESA; 9Z11E13E-18:3) is converted to 9Z11E-conjugated linoleic acid (CLA) in rats through a Delta13-saturation reaction. To investigate this further, we examined the absorption and metabolism of alpha-ESA in rat intestine using a lipid absorption assay in lymph from the thoracic duct. In this study, we used 4 test oils [tung oil, perilla oil, CLA-triacylglycerol (TG), and pomegranate seed oil, containing alpha-ESA, alpha-linolenic acid (LnA; 9Z12Z15Z-18:3), CLA, and punicic acid (PA; 9Z11E13Z-18:3), respectively]. Emulsions containing the test oils were administered to rats, and lymph from the thoracic duct was collected over 24 h. The positional and geometrical isomerism of CLA produced by PA metabolism was determined using GC-electron impact (EI)-MS and (13)C-NMR, respectively; the product was confirmed to be 9Z11E-CLA. A part of alpha-ESA and PA was converted to 9Z11E-CLA 1 h after administration; therefore the lymphatic recoveries of alpha-ESA and PA were modified by the amount of recovered CLA. Cumulative recovery of CLA, alpha-ESA, and PA was lower than that of LnA only during h 1 (P < 0.05), and cumulative recovery of alpha-ESA and PA was significantly lower than that of LnA and CLA for 8 h (P < 0.05). Therefore, the absorption rate was LnA > CLA > alpha-ESA = PA. The conversion ratio of alpha-ESA to 9Z11E-CLA was higher than that of PA to 9Z11E-CLA over 24 h (P < 0.05). These results indicated that alpha-ESA and PA are slowly absorbed in rat intestine, and a portion of these fatty acids is quickly converted to 9Z11E-CLA.