An in vitro study reveals the nutraceutical potential of punicic acid relevant to diabetes via enhanced GLUT4 expression and adiponectin secretion

Synergistic effects of punicic acid and alpha lipoic acid ameliorate inflammatory and metabolic genes expression in C2C12 myoblast cells under oxidative stress condition

Inflammation is a reaction of the immune system to infection and injury; in fact, it positioned at the center of metabolic disorders, particularly obesity, type 2 diabetes, and cardiovascular diseases. Thus play a major role not only in their development, but also exerts as a crucial linking factor among those diseases. In this regard, one of the strategies for tackling this problem is application of antioxidants to treat such diseases. The present study was performed to evaluate the synergistic effects of punicic acid (PUA) and alpha-lipoic acid (ALA) as antioxidants and radical scavenging reagents on the expression of some inflammatory and metabolism-related genes under oxidative stress in the muscle cells. The experimental treatments consisted of a range of 20, 40, 80, 160, and 320 µM of PUA, and 5, 25, 50, 100, and 200 µM of ALA with a 200 µM concentration of H2 O2 as an oxidative stress inducer. Accordingly, fatty acid treatments were applied for 24 h, and H2 O2 was treated for 1 h. Our results indicated that the simultaneous treatment of PUA and ALA at optimal concentrations (80 and 50 µM, respectively) decreased the expression of inflammation genes and increased the expression of regulatory genes (Pparγ, Pgc-1α) related to metabolism (p < .05). Unexpectedly, H2 O2 treatment increased the Fndc5 expression (p < .05). Maximal upregulation of Pparγ, Pgc-1α were obtained when fatty acids combination (PUA and ALA) were used in the culture of H2 O2 treated cells (p < .05). Therefore, our findings suggest that the simultaneous use of PUA and ALA fatty acids could reduce oxidative stress, and the expression of inflammatory genes, thereby improving the cell metabolism.

Anti-obesity potential of a yogurt functionalized with a CLNA-rich pomegranate oil

Pomegranate oil is rich in conjugated linolenic acids, compounds which have attracted attention due to their potential applicability in obesity management as they are capable of modulating leptin and adiponectin secretion and regulate fatty acids storage and glucose metabolism. Among the possible bioactive foodstuffs capable of delivering these bioactive compounds yogurts have shown potential. Thus, the purpose of this work was to develop functional yogurts through the addition of pomegranate oil either in its free or encapsulated (used as a protective strategy against oxidation and gastrointestinal tract passage) forms. To that end, the pomegranate oil (free and encapsulated) was incorporated in yogurt and the functional yogurt capacity to modulate hepatic lipid accumulation, adipocyte metabolism (in terms of lipolysis, and adipokines secretion) and immune response was evaluated. The results obtained showed that the pomegranate oil's incorporation led to an improvement in the yogurts' nutritional values, with a reduction in its atherogenic and thrombogenic indexes (more than 78% for atherogenic and 76% for thrombogenic index) and an enhancement of its hypocholesterolemic/hypercholesterolemic ratio (more than 62%) when compared to the control yogurt. Furthermore, data also showed for the first time how these functional yogurts promoted modulation of metabolic processes post GIT as they were capable of reducing by 40% triglycerides accumulation in steatosis-induced Hep G2 cells and by 30 % in differentiated adipocytes. Moreover, samples also showed a capacity to modulate the leptin and adiponectin secretion (56 % of increase in adiponectin) and reduce the IL-6 secretion (ca 44%) and TNF-α (ca 12%) in LPS-stimulated cells. Thus, the CLNA-rich yogurt here developed showed potential as a viable nutraceutical alternative for obesity management.

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.

Therapeutic Potential of Pomegranate in Metabolic Disorders

Metabolic syndrome and associated disorders have become one of the major challenging health problems over the last decades. Considerable attention has been paid to natural products and herbal medicines for the management of metabolic disorders in recent years. Many studies have investigated the therapeutic effects of different parts (arils, peels, seeds, and flowers) of pomegranate (Punica granatum L.) for the prevention and treatment of this syndrome. This study aims to provide an updated review on the in vitro and in vivo studies as well as clinical trials investigating the effects of pomegranate and its active compounds on different components of metabolic problems such as hyperglycemia, hyperlipidemia, hypertension, as well as obesity over the last two decades. Besides, the key mechanisms by which pomegranate affects these pathogenic conditions are also discussed. The studies show that although pomegranate has promising beneficial effects on diabetes, hypertension, hyperlipidemia, and obesity in various cellular, animal, and clinical models of studies, there are some conflicting results, particularly for hyperglycemic conditions. The main mechanisms include influencing oxidative stress and anti-inflammatory responses. Overall, pomegranate seems to have positive effects on the pathogenic conditions of metabolic syndrome according to the reviewed studies. Although pomegranate is not suggested as the first line of therapy or monotherapy, it could be only used as an adjunctive therapy. Nevertheless, further large and long-term clinical studies are still required.

Dietary Polyphenols and Gene Expression in Molecular Pathways Associated with Type 2 Diabetes Mellitus: A Review

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder with various contributing factors including genetics, epigenetics, environment and lifestyle such as diet. The hallmarks of T2DM are insulin deficiency (also referred to as β-cell dysfunction) and insulin resistance. Robust evidence suggests that the major mechanism driving impaired β-cell function and insulin signalling is through the action of intracellular reactive oxygen species (ROS)-induced stress. Chronic high blood glucose (hyperglycaemia) and hyperlipidaemia appear to be the primary activators of these pathways. Reactive oxygen species can disrupt intracellular signalling pathways, thereby dysregulating the expression of genes associated with insulin secretion and signalling. Plant-based diets, containing phenolic compounds, have been shown to exhibit remedial benefits by ameliorating insulin secretion and insulin resistance. The literature also provides evidence that polyphenol-rich diets can modulate the expression of genes involved in insulin secretion, insulin signalling, and liver gluconeogenesis pathways. However, whether various polyphenols and phenolic compounds can target specific cellular signalling pathways involved in the pathogenesis of T2DM has not been elucidated. This review aims to evaluate the modulating effects of various polyphenols and phenolic compounds on genes involved in cellular signalling pathways (both in vitro and in vivo from human, animal and cell models) leading to the pathogenesis of T2DM.

Phloretin and phloridzin improve insulin sensitivity and enhance glucose uptake by subverting PPARγ/Cdk5 interaction in differentiated adipocytes

Activators of peroxisome proliferator-activated receptor-γ (PPARγ agonists) are therapeutically promising candidates against insulin resistance and hyperglycemia. Synthetic PPARγ agonists are known to effectively enhance insulin sensitivity, but these are also associated with adverse side-effects and rising cost of treatment. Therefore, natural PPARγ targeting ligands are desirable alternatives for the management of insulin resistance associated with type 2 diabetes. Phloretin (PT) and Phloridzin (PZ) are predominant apple phenolics, which are recognized for their various pharmacological functions. The present study assessed the potential of PT and PZ in enhancing insulin sensitivity and glucose uptake by inhibiting Cdk5 activation and corresponding PPARγ phosphorylation in differentiated 3T3L1 cells. In silico docking and subsequent validation using 3T3L1 cells revealed that PT and PZ not only block the ser273 site of PPARγ but also inhibit the activation of Cdk5 itself, thereby, indicating their potent PPARγ regulatory attributes. Corroborating this, application of PT and PZ significantly enhanced the accumulation of cellular triglycerides as well as expression of insulin-sensitizing genes in adipocytes ultimately resulting in improved glucose uptake. Taken together, the present study reports that PT and PZ inhibit Cdk5 activation, which could be directly influencing the apparent PPARγ inhibition at ser273, ultimately resulting in improved insulin sensitivity and glucose uptake.

Pomegranate polyphenols and urolithin A inhibit α-glucosidase, dipeptidyl peptidase-4, lipase, triglyceride accumulation and adipogenesis related genes in 3T3-L1 adipocyte-like cells

ETHNOPHARMACOLOGICAL RELEVANCE

Pomegranate fruit is considered an antidiabetic medicine in certain systems of traditional medicine. In addition, pomegranate polyphenols are known as powerful antioxidants with beneficial effects such as the reduction of oxidative / inflammatory stress and the increase of protective signalling such as antioxidant enzymes, neurotrophic factors and cytoprotective proteins.

AIM OF THE STUDY

This work evaluates the effects of pomegranate juice, its main polyphenols known as ellagic acid and punicalagin, as well as its main metabolite urolithin A, on physiological and pharmacological targets of metabolic diseases such as obesity and diabetes.

MATERIALS AND METHODS

For this purpose, enzyme inhibition bioassays of lipase, α-glucosidase and dipeptidyl peptidase-4 were carried out in cell-free systems. Similarly, adipocytes derived from 3T3-L1 cells were employed to study the effects of ellagic acid, punicalagin and urolithin A on adipocyte differentiation and triglyceride (TG) accumulation.

RESULTS

Pomegranate juice, ellagic acid, punicalagin and urolithin A were able to inhibit lipase, α-glucosidase and dipeptidyl peptidase-4. Furthermore, all tested compounds but significantly the metabolite urolithin A displayed anti-adipogenic properties in a dose-dependent manner as they significantly reduced TG accumulation and gene expression related to adipocyte formation such as adiponectin, PPARγ, GLUT4, and FABP4 in 3T3-L1 adipocytes.

CONCLUSION

These results may explain from a molecular perspective the beneficial effects and traditional use of pomegranate in the prevention of metabolic-associated disorders such as obesity, diabetes and related complications.

Licarin B from Myristica fragrans improves insulin sensitivity via PPARγ and activation of GLUT4 in the IRS-1/PI3K/AKT pathway in 3T3-L1 adipocytes

Licarin B, a major bioactive compound isolated fromMyristica fragransmace improves glucose uptakeviaPPARγ and GLUT4 translocation in IRS-1/PI3K/AKT pathway in adipocytes

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.

Insulin resistance by TNF-α is associated with mitochondrial dysfunction in 3T3-L1 adipocytes and is ameliorated by punicic acid, a PPARγ agonist

Punicic acid (PA), a poly unsaturated fatty acid found abundantly in pomegranate seed oil is reported to have PPARγ agonist property. TNF-α mediated insulin resistance plays an important role in the pathogenesis of diabetes and is associated with severe mitochondrial impairment. In this study, PA was evaluated for its ability to ameliorate TNF-α induced mitochondrial dysfunctions in 3T3-L1 adipocytes. For this, we examined the alterations in mitochondrial energetics, biogenesis, transmembrane potential and dynamics in TNF-α induced insulin resistant model of 3T3-L1 adipocytes. PA improved glucose uptake, ROS accumulation, mitochondrial biogenesis and energetics in TNF-α treated cells. In addition, treatment with PA was found to ameliorate TNF-α induced alterations in proteins associated with mitochondrial dynamics like FIS1 and OPA1. These findings suggest that PA can be considered as an active lead for the management of insulin resistance and associated mitochondrial dysfunctions.

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.

Avocado Oil Improves Mitochondrial Function and Decreases Oxidative Stress in Brain of Diabetic Rats

Diabetic encephalopathy is a diabetic complication related to the metabolic alterations featuring diabetes. Diabetes is characterized by increased lipid peroxidation, altered glutathione redox status, exacerbated levels of ROS, and mitochondrial dysfunction. Although the pathophysiology of diabetic encephalopathy remains to be clarified, oxidative stress and mitochondrial dysfunction play a crucial role in the pathogenesis of chronic diabetic complications. Taking this into consideration, the aim of this work was to evaluate the effects of 90-day avocado oil intake in brain mitochondrial function and oxidative status in streptozotocin-induced diabetic rats (STZ rats). Avocado oil improves brain mitochondrial function in diabetic rats preventing impairment of mitochondrial respiration and mitochondrial membrane potential (ΔΨ m ), besides increasing complex III activity. Avocado oil also decreased ROS levels and lipid peroxidation and improved the GSH/GSSG ratio as well. These results demonstrate that avocado oil supplementation prevents brain mitochondrial dysfunction induced by diabetes in association with decreased oxidative stress.

Chebulagic acid from Terminalia chebula enhances insulin mediated glucose uptake in 3T3-L1 adipocytes via PPARγ signaling pathway

The thiazolidinedione (TZDs) class of drugs are very effective for the treatment of type 2 diabetes mellitus (T2DM). But due to the adverse effects of synthetic TZDs, their use is strictly regulated. The therapeutic actions of TZDs are mediated via modulation of peroxisome proliferator-activated receptor gamma (PPARγ). Naturally occurring PPARγ modulators are more desirable as they lack the serious adverse effects caused by TZDs. This has prompted the exploitation of medicinal plants used in traditional medicine, for their potential PPARγ activity. In the present work, we studied chebulagic acid (CHA) isolated from fruits of Terminalia chebula with respect to its effect on adipogenesis, glucose transport, and endocrine function of adipocyte. The mRNA expression profile of PPARγ target gene CCAAT/enhancer-binding protein alpha (C/EBP-α) was analyzed by qRT-PCR. The putative binding mode and the potential ligand-target interactions of CHA, with PPARγ was analyzed using docking software (Autodock and iGEMDOCKv2). The results showed that CHA enhances PPARγ signaling and adipogenesis dose dependently but in a moderate way, less than rosiglitazone. GLUT4 expression and adiponectin secretion was increased by CHA treatment. The mRNA expression of PPARγ target gene C/EBP-α was increased in CHA -treated adipocytes. The comparison of results of various parameters of adipogenesis, insulin sensitivity, endocrine function and molecular docking experiments of roziglitazone and chebulagic acid indicate that the latter behaves like partial PPARγ agonist which could be exploited for phytoceutical development against T2DM.