Grape-seed derived procyanidins interfere with adipogenesis of 3T3-L1 cells at the onset of differentiation

Harnessing the Power of Polyphenols: A New Frontier in Disease Prevention and Therapy

There are a wide variety of phytochemicals collectively known as polyphenols. Their structural diversity results in a broad range of characteristics and biological effects. Polyphenols can be found in a variety of foods and drinks, including fruits, cereals, tea, and coffee. Studies both in vitro and in vivo, as well as clinical trials, have shown that they possess potent antioxidant activities, numerous therapeutic effects, and health advantages. Dietary polyphenols have demonstrated the potential to prevent many health problems, including obesity, atherosclerosis, high blood sugar, diabetes, hypertension, cancer, and neurological diseases. In this paper, the protective effects of polyphenols and the mechanisms behind them are investigated in detail, citing the most recent available literature. This review aims to provide a comprehensive overview of the current knowledge on the role of polyphenols in preventing and managing chronic diseases. The cited publications are derived from in vitro, in vivo, and human-based studies and clinical trials. A more complete understanding of these naturally occurring metabolites will pave the way for the development of novel polyphenol-rich diet and drug development programs. This, in turn, provides further evidence of their health benefits.

Black soybean seed coat polyphenols have different effects on glucose and lipid metabolism in growing and young adult mice

Black soybean contains flavan-3-ols and cyanidin 3-O-glucoside in its seed coat. Polyphenol-rich black soybean seed coat extract (BE) possesses various health benefits, such as antioxidant, anti-obesity, and anti-hyperglycemic effects. However, these functions have been evaluated mainly in the growing stage of animals, and there is no comparison data for different life stages. In this present study, we compared the effect of BE in growing (5-week old) and young adult (22-week old) ICR male mice. These mice were given an AIN 93M diet containing 2.0% BE for 4 weeks. BE did not affect body weight gain in both growing and young adult mice, but it suppressed mesenteric and subcutaneous white adipose tissue weights and decreased the cell size. BE also significantly suppressed plasma free-fatty acid levels. The effect of both BE and life stages were observed in the protein expression of adipogenesis-related transcription factors; in particular, BE suppressed the expression of C/EBPα and PPARγ. No significant change was observed in lipolysis and lipogenesis factors in the white adipose tissue and liver. Alternatively, BE showed low glucose tolerance without affecting plasma insulin levels after glucose loading in young adult mice, as seen from the results of the oral glucose tolerance test. However, plasma glucose and insulin levels remained unchanged at the end of the experimental period. In conclusion, these results strongly suggest that the health-beneficial effects of BE may alter in mice at different life stages.

Insights on Dietary Polyphenols as Agents against Metabolic Disorders: Obesity as a Target Disease

Obesity is a condition that leads to increased health problems associated with metabolic disorders. Synthetic drugs are available for obesity treatment, but some of these compounds have demonstrated considerable side effects that limit their use. Polyphenols are vital phytonutrients of plant origin that can be incorporated as functional food ingredients. This review presents recent developments in dietary polyphenols as anti-obesity agents. Evidence supporting the potential application of food-derived polyphenols as agents against obesity has been summarized. Literature evidence supports the effectiveness of plant polyphenols against obesity. The anti-obesity mechanisms of polyphenols have been explained by their potential to inhibit obesity-related digestive enzymes, modulate neurohormones/peptides involved in food intake, and their ability to improve the growth of beneficial gut microbes while inhibiting the proliferation of pathogenic ones. Metabolism of polyphenols by gut microbes produces different metabolites with enhanced biological properties. Thus, research demonstrates that dietary polyphenols can offer a novel path to developing functional foods for treating obesity. Upcoming investigations need to explore novel techniques, such as nanocarriers, to improve the content of polyphenols in foods and their delivery and bioavailability at the target sites in the body.

The effects of grape seed proanthocyanidins in cafeteria diet-induced obese Fischer 344 rats are influenced by faecal microbiota in a photoperiod dependent manner

Polyphenols are of high interest due to their beneficial health effects, including anti-obesity properties. The gut microbiota may play an important role in polyphenol-mediated effects as these bacteria are significantly involved in the metabolism of polyphenols. Moreover, seasonal rhythms have been demonstrated to influence both the gut microbiota composition and polyphenol bioavailability. Thus, the goal of this study was to evaluate the impact of photoperiods and microbiota on polyphenol functionality in an obesogenic context. Towards this aim, cafeteria diet-fed Fischer 344 rats were housed under three different photoperiod conditions (L6: 6 h of light, L12: 12 h of light and L18: 18 h of light) for 9 weeks. During the last 4 weeks of the experiment, rats were daily administered with an oral dose of a grape seed proanthocyanidin extract (GSPE) (25 mg per kg body weight). Additionally, rats treated with GSPE and an antibiotic cocktail (ABX) in their drinking water were included for a better understanding of the gut microbiota role in GSPE functionality. Vehicle and non-ABX treated rats were included as controls. GSPE decreased body weight gain and fat depots only under L18 conditions. Interestingly, the gut microbiota composition was strongly altered in this photoperiod. GSPE + ABX-treated rats gained significantly less body weight compared to the rats of the rest of the treatments under L18 conditions. These results suggest that GSPE functionality is modulated by the gut microbiota in a photoperiod dependent manner. These novel findings corroborate seasonal rhythms as key factors that must be taken into account when investigating the effects of polyphenols in the treatment or prevention of chronic diseases.

Polyphenol Supplementation Did Not Affect Insulin Sensitivity and Fat Deposition During One-Month Overfeeding in Randomized Placebo-Controlled Trials in Men and in Women

Two randomized placebo-controlled double-blind paralleled trials (42 men in Lyon, 19 women in Lausanne) were designed to test 2 g/day of a grape polyphenol extract during 31 days of high calorie-high fructose overfeeding. Hyperinsulinemic-euglycemic clamps and test meals with [1,1,1-¹³C₃]-triolein were performed before and at the end of the intervention. Changes in body composition were assessed by dual-energy X-ray absorptiometry (DEXA). Fat volumes of the abdominal region and liver fat content were determined in men only, using 3D-magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) at 3T. Adipocyte's size was measured in subcutaneous fat biopsies. Bodyweight and fat mass increased during overfeeding, in men and in women. While whole body insulin sensitivity did not change, homeostasis model assessment of insulin resistance (HOMA-IR) and the hepatic insulin resistance index (HIR) increased during overfeeding. Liver fat increased in men. However, grape polyphenol supplementation did not modify the metabolic and anthropometric parameters or counteract the changes during overfeeding, neither in men nor in women. Polyphenol intake was associated with a reduction in adipocyte size in women femoral fat. Grape polyphenol supplementation did not counteract the moderated metabolic alterations induced by one month of high calorie-high fructose overfeeding in men and women. The clinical trials are registered under the numbers NCT02145780 and NCT02225457 at ClinicalTrials.gov and available at https://clinicaltrials.gov/ct2/show/NCT02145780 and https://clinicaltrials.gov/ct2/show/NCT02225457.

Dietary Flavonoids as Modulators of Lipid Metabolism in Poultry

Flavonoids, naturally-occurring compounds with multiple phenolic structures, are the most widely distributed phytochemicals in the plant kingdom, and are mainly found in vegetables, fruits, grains, roots, herbs, and tea and red wine products. Flavonoids have health-promoting effects and are indispensable compounds in nutritional and pharmaceutical (i.e., nutraceutical) applications. Among the demonstrated bioactive effects of flavonoids are anti-oxidant, anti-inflammatory, and anti-microbial in a range of research models. Through dietary formulation strategies, numerous flavonoids provide the ability to support bird health while improving the nutritional quality of poultry meat and eggs by changing the profile of fatty acids and reducing cholesterol content. A number of such compounds have been shown to inhibit adipogenesis, and promote lipolysis and apoptosis in adipose tissue cells, and thereby have the potential to affect fat accretion in poultry at various ages and stages of production. Antioxidant and anti-inflammatory properties contribute to animal health by preventing free radical damage in tissues and ameliorating inflammation in adipose tissue, which are concerns in broiler breeders and laying hens. In this review, we summarize the progress in understanding the effects of dietary flavonoids on lipid metabolism and fat deposition in poultry, and discuss the associated physiological mechanisms.

Plant Extracts in Obesity: A Role of Gut Microbiota

Obesity has become one of the most serious chronic diseases threatening human health. Its occurrence and development are closely associated with gut microbiota since the disorders of gut microbiota can promote endotoxin production and induce inflammatory response. Recently, numerous plant extracts have been proven to mitigate lipid dysmetabolism and obesity syndrome by regulating the abundance and composition of gut microbiota. In this review, we summarize the potential roles of different plant extracts including mulberry leaf extract, policosanol, cortex moutan, green tea, honokiol, and capsaicin in regulating obesity via gut microbiota. Based on the current findings, plant extracts may be promising agents for the prevention and treatment of obesity and its related metabolic diseases, and the mechanisms might be associated with gut microbiota.

Proanthocyanidins and Where to Find Them: A Meta-Analytic Approach to Investigate Their Chemistry, Biosynthesis, Distribution, and Effect on Human Health

Proanthocyanidins (PACs) are a class of polyphenolic compounds that are attracting considerable interest in the nutraceutical field due to their potential health benefits. However, knowledge about the chemistry, biosynthesis, and distribution of PACs is limited. This review summarizes the main chemical characteristics and biosynthetic pathways and the main analytical methods aimed at their identification and quantification in raw plant matrices. Furthermore, meta-analytic approaches were used to identify the main plant sources in which PACs were contained and to investigate their potential effect on human health. In particular, a cluster analysis identified PACs in 35 different plant families and 60 different plant parts normally consumed in the human diet. On the other hand, a literature search, coupled with forest plot analyses, highlighted how PACs can be actively involved in both local and systemic effects. Finally, the potential mechanisms of action through which PACs may impact human health were investigated, focusing on their systemic hypoglycemic and lipid-lowering effects and their local anti-inflammatory actions on the intestinal epithelium. Overall, this review may be considered a complete report in which chemical, biosynthetic, ecological, and pharmacological aspects of PACs are discussed.

A Mix of Natural Bioactive Compounds Reduces Fat Accumulation and Modulates Gene Expression in the Adipose Tissue of Obese Rats Fed a Cafeteria Diet

Scientists are focusing on bioactive ingredients to counteract obesity. We evaluated whether a mix containing grape seed proanthocyanidin extract (GSPE), anthocyanins, conjugated linoleic acid (CLA), and chicken feet hydrolysate (CFH) could reduce body fat mass and also determined which mechanisms in the white adipose tissue (WAT) and the brown adipose tissue (BAT) were affected by the treatment. The mix or vehicle (VH) were administered for three weeks to obese rats fed a cafeteria (CAF) diet. Biometric measures, indirect calorimetry, and gene expression in WAT and BAT were analyzed as was the histology of the inguinal WAT (IWAT). The individual compounds were also tested in the 3T3-L1 cell line. The mix treatment resulted in a significant 15% reduction in fat (25.01 ± 0.91 g) compared to VH treatment (21.19 ± 1.59 g), and the calorimetry results indicated a significant increase in energy expenditure and fat oxidation. We observed a significant downregulation of Fasn mRNA and an upregulation of Atgl and Hsl mRNA in adipose depots in the group treated with the mix. The IWAT showed a tendency of reduction in the number of adipocytes, although no differences in the total adipocyte area were found. GSPE and anthocyanins modulated the lipid content and downregulated the gene and protein levels of Fasn compared to the untreated group in 3T3-L1 cells. In conclusion, this mix is a promising treatment against obesity, reducing the WAT of obese rats fed a CAF diet, increasing energy expenditure and fat oxidation, and modifying the expression of genes involved in lipid metabolism of the adipose tissue.

Long Term Exposure to a Grape Seed Proanthocyanidin Extract Enhances L-Cell Differentiation in Intestinal Organoids

SCOPE

A grape-seed proanthocyanidin extract (GSPE) interacts at the intestinal level, enhancing glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) release, which modulate appetite and glucose homeostasis. Thus, enhancing L-cell numbers could be a strategy to promote hormone production, providing a potential strategy for obesity and type-2 diabetes mellitus (T2DM) treatment.

METHODS AND RESULTS

Mice ileum organoids are used to evaluate the long-term effects of GSPE and two of its main components, epicatechin (EC) and gallic acid (GA), on intestinal differentiation. Hormone levels are determined using RIA and ELISA kits, and gene expression of transcription factors involved in intestinal cell differentiation, as well as markers of different cell types, are assessed by real-time qPCR. GSPE upregulates enterohormone gene expression and content, as well as the pan-endocrine marker chromogranin A. GSPE also modulates the temporal gene expression profile of early and late transcription factors involved in L-cell differentiation. Furthermore, GSPE upregulates goblet cell (Muc2) and enterocyte (sucraseisomaltase) markers, while downregulating stem cell markers (Lgr5+). Although EC and GA modified enterohormone release, they do not reproduce GSPE effects on transcription factor's profile.

CONCLUSIONS

This study shows the potential role of GSPE in promoting enteroendocrine differentiation, effect that is not mediated by EC or GA.

Viburnum opulus L. Juice Phenolics Inhibit Mouse 3T3-L1 Cells Adipogenesis and Pancreatic Lipase Activity

Viburnum opulus L. fruit is a rich source of phenolic compounds that may be involved in the prevention of metabolic diseases. The purpose of this study was to determine the effects of Viburnum opulus fresh juice (FJ) and juice purified by solid-phase extraction (PJ) on the adipogenesis process with murine 3T3-L1 preadipocyte cell line and pancreatic lipase activity in triolein emulsion, as well as their phenolic profiles by UPLC/Q-TOF-MS. Decrease of lipids and triacylglycerol accumulation in differentiated 3T3-L1 cells were in concordance with downregulation of the expression of peroxisome proliferator-activated receptor-gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPβ/α), and sterol regulatory element-binding protein 1c (SREBP-1c). Furthermore, regulation of PPARγ-mediated β-lactamase expression by V. opulus components in reporter gene assay, as well as their binding affinity to ligand-binding domain of PPARγ, were tested. In addition, the levels of enzymes involved in lipid metabolism, like fatty acid synthase (FAS) or acetyl-CoA carboxylase (ACC), were decreased, along with inflammatory cytokines, like tumor necrosis factorα (TNFα), interleukin-6 (Il-6) and leptin. Moreover, FJ and PJ were able to inhibit pancreatic lipase, which potentially could reduce the fat absorption from the intestinal lumen and the storage of body fat in the adipose tissues. Thirty-two phenolic compounds with chlorogenic acid as the dominant compound were identified in PJ which revealed significant biological activity. These data contribute to elucidate V. opulus juice phenolic compounds’ molecular mechanism in adipogenesis regulation in 3T3-L1 cells and dietary fat lipolysis.

Effects of Grape Seed Proanthocyanidin Extract on Obesity

Obesity is a chronic metabolic disease resulting from excessive fat accumulation and/or abnormal distribution caused by multiple factors. As a major component of metabolic syndrome, obesity is closely related to many diseases such as type 2 diabetes mellitus, hyperlipidemia, hypertension, coronary heart disease, stroke and cancer. Hence, the problem of obesity cannot be ignored, and recent studies have shown that grape seed proanthocyanidin extract (GSPE) has an antiobesity effect. This paper systematically reviews the research progress and potential mechanism of GSPE emphasizing on obesity prevention and treatment.

Long-Lasting Effects of GSPE on Ileal GLP-1R Gene Expression Are Associated with a Hypomethylation of the GLP-1R Promoter in Female Wistar Rats

Flavonoids have been shown to modulate GLP-1 in obesity. GLP-1 induces some of its effects through the intestinal GLP-1 receptor (GLP-1R), though no data exist on how flavonoids affect this receptor. Here, we examine how a dose of grape seed proanthocyanidin extract (GSPE) with anti-obesity activity affects intestinal GLP-1R and analyze whether epigenetics play a role in the long-lasting effects of GSPE. We found that 10-day GSPE administration prior to the cafeteria diet upregulated GLP-1R mRNA in the ileum 17 weeks after the GSPE treatment. This was associated with a hypomethylation of the GLP-1R promoter near the region where the SP1 transcription factor binds. In the colon, the cafeteria diet upregulated GLP-1R without showing any GSPE effect. In conclusion, we have identified long-lasting GSPE effects on GLP-1R gene expression in the ileum that are partly mediated by hypomethylation at the gene promoter and may affect the SP1 binding factor.

A Mixture of Functional Complex Extracts from Lycium barbarum and Grape Seed Enhances Immunity Synergistically In Vitro and In Vivo

A mixture of multiple ingredients is often more effective than the individual ingredients. The functions of Lycium barbarum polysaccharide (LBP) glycoconjugate and grape seed procyanidins (GSP) are widely known. Here, we investigated the synergistic immune-enhancing activity of LBP and GSP. Atomic force microscopy results suggested that the mixture of LBP and GSP exhibited circular structure unlike LBP alone, and the addition of polyphenols may change the spatial conformation of the sugar chain. The changes in the structure were related to the synergistic effect of the two functional agents on immune recovery. In vitro, the proliferation rate of splenocytes was higher in LBP + GSP group (64.16%), rather than the sum of LBP group (13.01%) and GSP group (43.61%) individually used. This synergistical proliferation of splenocytes may be correlated to the increasing intracellular free calcium levels. Furthermore, the mixture significantly enhanced the immunity in vivo, as evident from the recovery of peripheral white blood cell counts in LBP + GSP group (18.535 × 10⁹ /L) to normal group levels (18.115 × 10⁹ /L) and higher B cell proliferation than normal group (P < 0.05). These results highlight the immune-enhancing activity of the combination of LBP and GSP associated with the structural changes, which may facilitate the development of functional foods with fewer resources but enhanced activities. PRACTICAL APPLICATION: The synergistic effects of LBP and GSP on immunomodulatory were better than the sum of the effects of the individual agents both in vitro and in vivo. Our results may provide a research-based support for the development of related functional products and an insight into the production of food resources with a fewer but more effective functional agents for better results.

Grape seed procyanidin extract inhibits adipogenesis and stimulates lipolysis of porcine adipocytes in vitro

The objective of this article was to evaluate in vitro effect of grape seed procyanidin extract (GSPE) on differentiation, proliferation, and lipolysis of porcine adipocytes, providing a molecular basis for the use of GSPE in pig fat regulation. Primary preadipocytes isolated from subcutaneous adipose tissue of pigs were used as the in vitro cell model. Treatment of GSPE repressed preadipocyte differentiation, as evidenced by reduced lipid accumulation, decreased mRNA expressions of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid-binding protein 4 (FABP4), as well as enhanced expressions of preadipocyte factor-1. Activity of glycerol-3-phosphate dehydrogenase (GPDH), one of the most important enzymes in the pathway for triacylglycerol biosynthesis, was also decreased. Furthermore, GSPE could suppress preadipocyte proliferation by inducing G0/G1 cell cycle arrest and cell apoptosis. In porcine mature adipocytes, treatment with GSPE attenuated lipid content and GPDH activity, and the release of both free fatty acid and glycerol were enhanced; mRNA expressions of key lipolytic transcription factors, including hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL), were elevated in GSPE-treated adipocytes. In summary, our results suggest GSPE inhibits porcine preadipocyte differentiation and proliferation and stimulates lipolysis of mature adipocytes, thus providing novel insights for further exploring the use of GSPE as a fat accumulation inhibitor.

Muscat Bailey A grape stalk extract ameliorates high-fat diet‑induced obesity by downregulating PPARγ and C/EPBα in mice

Muscat Bailey A grape stalk is an organic waste produced in marked amounts during the vinification of grapes. Previous studies have indicated that grape stalk is rich in bioactive phenolic compounds, and exhibits antioxidant and UV‑protective activities. However, its effects on obesity and obesity‑associated disorders have not yet been investigated. The effects of grape stalk extract on improving metabolic features were examined using a high‑fat diet (HFD)‑induced obesity mouse model. Oral administration of 200 mg/kg/day grape stalk extract over 16 weeks markedly prevented HFD‑induced obesity, hepatic steatosis, diabetic symptoms and the risk of developing cardiovascular disease. Furthermore, grape stalk extract prevented oxidative stress and inflammation caused by HFD in mice. The beneficial effect may be associated with CCAAT/enhancer‑binding protein α and peroxisome‑proliferator‑activated receptor γ down-regulation in liver tissue. Collectively, the results of the present study indicated that grape stalk extract may be a potent functional food ingredient for preventing obesity, hepatic steatosis and type 2 diabetes.

Grape Seed Proanthocyanidins Improve White Adipose Tissue Expansion during Diet-Induced Obesity Development in Rats

The development of metabolic complications associated with obesity has been correlated with a failure of white adipose tissue (WAT) to expand. Our group has previously reported that a 12-week administration of grape seed proanthocyanidin extract (GSPE) together with an obesogenic diet mitigated the development of cardiometabolic complications in rats. Using the same cohort of animals, we aim to elucidate whether the prevention of cardiometabolic complications by proanthocyanidins is produced by a healthier expansion of visceral WAT and/or an induction of the browning of WAT. For this, adipocyte size and number in retroperitoneal WAT (rWAT) were determined by histological analyses, and the gene expression levels of markers of adipogenesis, browning, and WAT functionality were quantified by RT-qPCR. The long-term administration of GSPE together with an obesogenic diet expanded rWAT via an increase in the adipocyte number and a preventive decrease in the adipocyte size in a dose-dependent manner. At the molecular level, GSPE seems to induce WAT adipogenesis through the upregulation of peroxisome proliferator-activated receptor (Pparγ) in a Sirtuin 1 (Sirt1)-dependent manner. In conclusion, the healthier visceral WAT expansion induced by proanthocyanidins supplementation may explain the improvement in the cardiometabolic risks associated with obesogenic diets.

Grape seed proanthocyanidin supplementation reduces adipocyte size and increases adipocyte number in obese rats

Objectives:

White adipose tissue (WAT) expands through hypertrophy (increased adipocyte size) and/or hyperplasia (increased adipocyte number). Hypertrophy has been associated with insulin resistance and dyslipidemia independently of body composition and fat distribution. In contrast, hyperplasia protects against metabolic alterations. Proanthocyanidins, which are the most abundant flavonoids in the human diet, improve metabolic disturbances associated with diet-induced obesity without reducing body weight or adiposity. The aim of this study was to determine whether grape seed proanthocyanidin extract (GSPE) can modulate WAT expandability. Because GSPE also contains gallic acid, we also studied the capacity of gallic acid to remodel WAT.

Design:

Male Wistar rats were fed a standard chow diet (n=6) or a cafeteria diet (CAF) for 11 weeks. After 8 weeks, the CAF-fed animals were supplemented with 25 mg GSPE/kg body weight (n=6), 7 mg gallic acid/kg body weight (n=6) or the vehicle (n=6) for 3 weeks. Histological analyses were performed in the retroperitoneal (rWAT) and inguinal (iWAT) WAT to determine adipocyte size and number. Specific markers for adipogenesis and WAT functionality were analysed in rWAT using quantitative RT-PCR.

Results:

GSPE or gallic acid supplementation did not reduce weight gain or reverse and adiposity. However, GSPE reduced adipocyte size significantly in rWAT and moderately in iWAT and tripled the adipocyte number in rWAT. Gallic acid slightly reduced adipocyte size in rWAT and iWAT and doubled the adipocyte number in both WATs. In accordance with this adipogenic activity, Pref-1 and PPARγ tended to be overexpressed in rWAT of rats supplemented with GSPE. Moreover, GSPE supplementation increased Plin1 and Fabp4 expression and restored adiponectin expression completely, indicating a better functionality of visceral WAT.

Conclusions:

GSPE supplementation has anti-hypertrophic and hyperplasic activities in rats with established obesity, mainly in visceral WAT inducing a healthier expansion of WAT to match the surplus energy provided by the cafeteria diet.

Chronic administration of grape-seed polyphenols attenuates the development of hypertension and improves other cardiometabolic risk factors associated with the metabolic syndrome in cafeteria diet-fed rats

The effects of grape-seed polyphenols against the development of hypertension and other cardiometabolic conditions associated with the metabolic syndrome (MetS) were studied in rats fed a high-fat, high-carbohydrate diet, known as the cafeteria (CAF) diet. Two groups of Wistar rats were fed standard (STD) or CAF diets for 12 weeks. The CAF diet-fed rats were administered different doses of a low-molecular-weight grape-seed polyphenol extract (LM-GSPE) (25, 100 and 200 mg/kg per d) or vehicle daily, and the STD diet-fed rats were administered LM-GSPE (100 mg/kg per d) or vehicle using ten animals per group. Body weight (BW), waist perimeter (WP) and systolic and diastolic blood pressures (BP) by the tail-cuff method were recorded weekly. The animals were housed in metabolic chambers every 2 weeks to estimate daily food and liquid intakes and to collect faeces and urine samples. The plasma lipid profile was analysed at time 0 and on the 4th, 7th, 10th and 12th weeks of the experiment. Moreover, plasma leptin was measured at the end of the experiment. Results demonstrated that LM-GSPE, when administered with the CAF diet, attenuated the increase in BP, BW, WP and improved lipid metabolism in these animals. However, although the 25- and 100-mg/kg per d doses were sufficient to produce beneficial effects on BP and lipid metabolism, a 200-mg/kg per d dose was necessary to have an effect on BW and WP. The present findings suggest that LM-GSPE is a good candidate for a BP-lowering agent that can also ameliorate other conditions associated with the MetS.

Muscadine grape seed oil as a novel source of tocotrienols to reduce adipogenesis and adipocyte inflammation

Tocotrienols are unsaturated forms of vitamin E previously shown to reduce adipogenesis and adipose inflammation. In this study, muscadine grape seed oil (MGSO) was identified as a novel source of tocotrienols containing significant amounts of α- and γ-tocotrienol (T3) with minor seasonal changes. The aim of this study was to assess the anti-adipogenic and anti-inflammatory potential of MGSO by using primary human adipose-derived stem cells (hASCs). Differentiating hASCs were treated with MGSO and compared with rice bran and olive oil. Accumulation of triglyceride was significantly lower in MGSO-treated hASCs than rice bran and olive oils. A tocotrienol rich fraction (TRF) from MGSO was prepared by solid phase extraction and eluted with 15% 1,4-dioxane in hexane. The MGSO-derived TRF treatment significantly reduced mRNA and protein expression that are crucial to adipogenesis (e.g., PPARγ and aP2) in hASCs. Furthermore, TRF from MGSO markedly reduced LPS-induced proinflammatory gene expression in human adipocytes and cytokine secretion to the medium (IL-6 and IL-8). Collectively, our work suggests that MGSO is a stable and reliable natural source of T3 and MGSO may constitute a new dietary strategy to attenuate obesity and its associated adipose inflammation.

Anti-inflammatory effects of grape seed procyanidin B2 on a diabetic pancreas

The prevalence of type 2 diabetes mellitus (T2DM) has increased considerably in recent years, highlighting the importance of developing new therapeutic strategies. Insulin-resistance and gradual dysfunction of pancreatic islets are the mainstay in the progression of T2DM. Therefore, preserving the function of the pancreas may lead to new prospective approaches. Our previous studies suggested that grape seed procyanidin B2 (GSPB2), a natural polyphenol product, exhibited protective effects on diabetic vasculopathy. However, effects of GSPB2 on a diabetic pancreas remain unknown. In this study, we provided strong evidence that GSPB2 exerted protective effects on a diabetic pancreas. GSPB2 attenuated the elevated body weights, food intake and advanced glycation end-product (AGE) levels in db/db mice (p < 0.05), though it had no significant effect on glucose levels. The increased islet sizes, insulin levels, as well as HOMA-IR were also improved by GSPB2 treatment in db/db mice (p < 0.05). Milk fat globule epidermal growth factor-8 (MFG-E8), an estimated target of GSPB2 in our previous studies, was up-regulated in pancreatic tissues whereas GSPB2 treatment down-regulated the protein level (p < 0.05). Since MFG-E8 is highly involved in inflammation, we further investigate pro-inflammatory cytokines interleukin-1β (IL-1β) and NLRP3 levels. We found that levels of IL-1β and NLRP3 increased in a diabetic pancreas while GSPB2 treatment notably attenuated these alterations (p < 0.05). In conclusion, our results suggest that inflammation is involved in the damage of a diabetic pancreas and GSPB2 provides protective effects at least in part through anti-inflammation.

A combination of (+)-catechin and (-)-epicatechin underlies the in vitro adipogenic action of Labrador tea (Rhododendron groenlandicum), an antidiabetic medicinal plant of the Eastern James Bay Cree pharmacopeia

ETHNOPHARMACOLOGICAL RELEVANCE

Rhododendron groenlandicum (Oeder) Kron & Judd (Labrador tea) was identified as an antidiabetic plant through an ethnobotanical study carried out with the close collaboration of Cree nations of northern Quebec in Canada.

OBJECTIVES

In a previous study the plant showed glitazone-like activity in a 3T3-L1 adipogenesis bioassay. The current study sought to identify the active compounds responsible for this potential antidiabetic activity using bioassay guided fractionation based upon an in vitro assay that measures the increase of triglycerides content in 3T3-L1 adipocyte.

MATERIALS AND METHODS

Isolation and identification of the crude extract's active constituents was carried out. The 80% ethanol extract was fractionated using silica gel column chromatography. Preparative HPLC was then used to isolate the constituents. The identity of the isolated compounds was confirmed by UV and mass spectrometry.

RESULTS

Nine chemically distinct fractions were obtained and the adipogenic activity was found in fraction 5 (RGE-5). Quercetins, (+)-catechin and (-)-epicatechin were detected and isolated from this fraction. While (+)-catechin and (-)-epicatechin stimulated adipogenesis (238±26% and 187±21% relative to vehicle control respectively) at concentrations equivalent to their concentrations in the active fraction RGE-5, none afforded biological activity similar to RGE-5 or the plant's crude extract when used alone. When cells were incubated with a mixture of the two compounds, the adipogenic activity was close to that of the crude extract (280.7±27.8 vs 311± 30%).

CONCLUSION

Results demonstrate that the mixture of (+)-catechin and (-)-epicatechin is responsible for the adipogenic activity of Labrador tea. This brings further evidence for the antidiabetic potential of R. groenlandicum and provides new opportunities to profile active principles in biological fluids or in traditional preparations.

Anti-adipogenic constituents from Dioscorea opposita in 3T3-L1 cells

We previously reported the lipase inhibitory activity of the n-BuOH fraction of Dioscorea opposita (DOB) and its isolates. This study sought to evaluate their anti-adipogenic activity in terms of their effects on the adipogenic transcription factors peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) as well as phosphorylated AMP-activated protein kinase (p-AMPK) and carnitine palmitoyl transferase-1 (CPT-1). DOB apparently attenuated 3T3-L1 adipocyte differentiation (33.6% decrease at 20 µg/mL). In addition, a marked decrease (90.4%) in the expression of PPARγ was observed in the DOB-treated 3T3-L1 cells. Four isolates from DOB: (4E,6E)-1,7-bis(4-hydroxyphenyl)-4,6-heptadien-3-one (1), (3R,5R)-1,7-bis(4-hydroxy-3-methoxyphenyl)-3,5-heptanediol (2), batatasin I (3), and (1E,4E,6E)-1,7-bis(4-hydroxyphenyl)-1,4,6-heptatrien-3-one (4), suppressed adipocyte differentiation by inhibiting PPARγ at 20 µM (85.9%, 68.6%, 76.2%, and 90.2% decrease, respectively) and C/EBPα (51.7%, 3.1%, 20.9%, and 59.8% decrease, respectively). Batatasin I was found to increase p-AMPK and CPT-1 at a concentration of 20 µM in 3T3-L1 adipocytes, resulting in inhibiting adipogenesis. Taken together, batatasin I might be responsible for the anti-adipogenic effect of DOB via inhibition of PPARγ and C/EBPα and activation of p-AMPK and CPT-1.

Roles of proanthocyanidin rich extracts in obesity

Obesity is a multifactorial disorder involving an abnormal or excessive amount of body fat.

Effects of oxidized phospholipids on gene expression in RAW 264.7 macrophages: a microarray study

Oxidized phospholipids (oxPLs) are components of oxidized LDL (oxLDL). It is known that oxLDL activates expression of a series of atherogenic genes and their oxPLs contribute to their biological activities. In this study we present the effects of 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) and 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC) on gene expression in RAW 264.7 macrophages using cDNA microarrays. PGPC affected the regulation of 146 genes, whereas POVPC showed only very minor effects. PGPC preferentially influenced expression of genes related to cell death, angiogenesis, cholesterol efflux, procoagulant mechanisms, atherogenesis, inflammation, and cell cycle. Many of these effects are known from studies with oxLDL or oxidized 1-hexadecanoyl-2-eicosatetra-5′,8′,11′,14′-enoyl-sn-glycero-3-phosphocholine (oxPAPC), containing PGPC in addition to other oxPL species. It is known that POVPC efficiently reacts with proteins by Schiff base formation, whereas PGPC only physically interacts with its biological targets. POVPC seems to affect cell physiology to a great extent on the protein level, whereas PGPC gives rise to both the modulation of protein function and regulation on the transcriptional level.

A rapid method to determine colonic microbial metabolites derived from grape flavanols in rat plasma by liquid chromatography-tandem mass spectrometry

This study describes the development and validation of a liquid chromatography-mass spectrometry method for determination of a large number of flavanol colonic derivatives in biological samples. The method was validated with rat plasma after the intake of grape seed flavanols. The minimum plasma volume necessary to maintain good recovery values within the range of 83-110% for all of the standards was determined by micro solid-phase extraction (μ-SPE). In total, 16 commercial standards were used to measure 30 different phenolic compounds present at low concentration levels (micromolar). The chromatographic method enabled reliable quantification of plasma colonic flavanol derivatives with low limits of detection and quantification, achieving values of 0.03 nM and 0.10 nM, respectively. The developed method can be readily applied to determine all of the flavanol metabolites that are most likely responsible for the majority of biological effects of poorly absorbed flavanols.

Plant-derived food ingredients for stimulation of energy expenditure

The development of obesity is related to the regulation of energy intake, energy expenditure, and energy storage in the body. Increasing energy expenditure by inducing lipolysis followed by fat oxidation is one of the alternatives which could help to reverse this increasingly widespread condition. Currently, there is no approved drug targeting on stimulation of energy expenditure available. The use of herbal medicines has become a preferred alternative, supported by the classical consensus on the innocuity of herbal medicine vs synthetic drugs, something that often lacks a scientific basis (ban on Ephedra, for example). The inclusion of functional food in the daily diet has also been promoted although its efficacy requires further investigation. This review summarizes the results of recent work focused on the investigation of edible plant materials targeted at various important pathways related to stimulation of energy expenditure. The aim is to evaluate a number of plants that may be of interest for further studies because of their potential to provide novel lead compounds or functional foods which may be used to combat obesity, but require further studies to evaluate their antiobesity activity in humans.

Dietary supplementation of chardonnay grape seed flour reduces plasma cholesterol concentration, hepatic steatosis, and abdominal fat content in high-fat diet-induced obese hamsters

The mechanisms for the hypocholesterolemic and antiobesity effects of grape seed flours derived from white and red winemaking processing were investigated using male Golden Syrian hamsters fed high-fat (HF) diets supplemented with 10% partially defatted grape seed flours from Chardonnay (ChrSd), Cabernet Sauvignon (CabSd), or Syrah (SyrSd) pomace as compared to a HF control diet for 3 weeks. Hamsters fed the ChrSd diet had significantly lowered plasma total-, VLDL-, and LDL-cholesterol concentrations compared to the CabSd, SyrSd, and control diets. The improved plasma cholesterol after ChrSd was correlated with the up-regulation of hepatic genes related to cholesterol (CYP51) and bile acid (CYP7A1) synthesis as well as LDL-cholesterol uptake (LDLR). A reduction of hepatic lipid content was associated with altered expression of the genes related to lipid metabolism. However, fecal total lipid content was not changed. Expression of ileal apical sodium bile acid transporter (ASBT) was not affected by ChrSd, indicating unchanged ileal bile acid reabsorption. The antiobesity effect of the ChrSd diet appears to be related to expression of adipogenesis- and inflammation-related genes in adipose tissue. These findings suggest that flavonoid-rich Chardonnay grape seed flour induced cholesterol-lowering, antiobesity, and anti-inflammatory health benefits and attenuation of hepatic steatosis via regulation of gene expression related to cholesterol, bile acid, and lipid metabolism in liver and adipose tissue.

Grape seed procyanidin extract modulates proliferation and apoptosis of pancreatic beta-cells

Grape seed procyanidin extract (GSPE) modulates glucose homeostasis and insulinemia in several animal models. Under pathological conditions, insulin levels are dependent on pancreatic beta-cell functionality, as well as on the beta-cell mass expansion or apoptosis in the pancreas. In this study, we analysed the effects of GSPE on modulating apoptosis and proliferation in beta-cells. We tested the effects of GSPE in the INS-1E pancreatic beta-cell line, either under basal or altered conditions with high glucose, insulin or palmitate levels. GSPE enhanced the pro-apoptotic effect of high glucose and showed clear antiproliferative effects under high glucose, insulin and palmitate conditions. These antiproliferative effects are likely due to high molecular weight compounds contained in the extract. GSPE also modulated pro- and anti-apoptotic markers in the pancreas of rats fed a cafeteria diet, with the effect depending on the dose of GSPE and duration of treatment. Thus, GSPE is able to modulate apoptosis and proliferation of beta-cells under altered, but not basal, conditions.

Procyanidins improve some disrupted glucose homoeostatic situations: an analysis of doses and treatments according to different animal models

This review analyses the potential beneficial effects of procyanidins, the main class of flavonoids, in situations in which glucose homeostasis is disrupted. Because the disruption of glucose homeostasis can occur as a result of various causes, we critically review the effects of procyanidins based on the specific origin of each type of disruption. Where little or no insulin is present (Type I diabetic animals), summarized studies of procyanidin treatment suggest that procyanidins have a short-lived insulin-mimetic effect on the internal targets of the organism, an effect not reproduced in normoglycemic, normoinsulinemic healthy animals. Insulin resistance (usually linked to hyperinsulinemia) poses a very different situation. Preventive studies using fructose-fed models indicate that procyanidins may be useful in preventing the induction of damage and thus in limiting hyperglycemia. But the results of other studies using models such as high-fat diet treated rats or genetically obese animals are controversial. Although the effects on glucose parameters are hazy, it is known that procyanidins target key tissues involved in its homeostasis. Interestingly, all available data suggest that procyanidins are more effective when administered in one acute load than when mixed with food.

A berry thought-provoking idea: the potential role of plant polyphenols in the treatment of age-related cognitive disorders

Today, tens of millions of elderly individuals worldwide suffer from dementia. While the pathogenesis of dementia is complex and incompletely understood, it may be, at least to a certain extent, the consequence of systemic vascular pathology. The metabolic syndrome and its individual components induce a proinflammatory state that damages blood vessels. This condition of chronic inflammation may damage the vasculature of the brain or be directly neurotoxic. Associations have been established between the metabolic syndrome, its constituents and dementia. A relationship has also been observed between certain dietary factors, such as constituents of the 'Mediterranean diet', and the metabolic syndrome; similar associations have been noted between these dietary factors and dementia. Fruit juices and extracts are under investigation as treatments for cognitive impairment. Blueberry, strawberry, blackberry, grape and plum juices or extracts have been successfully tested in cognitively impaired rodents. Published trials of the benefits of grape and blueberry juice in the treatment of small numbers of cognitively impaired persons have recently appeared. The benefits of fruit products are thought to be a result of its polyphenol content. A grape polyphenol found in grapes, resveratrol, now being studied in humans, and one in grapes and blueberries, pterostilbene, have been found to improve cognition in rodents. In the design of future human trials, one ought to consider the poor bioavailability of these products, the possible need to initiate the experimental therapy long before the onset of symptoms, and currently limited knowledge about the appropriate form (e.g. juice, powder or individual polyphenol) of treatment.

Procyanidins modify insulinemia by affecting insulin production and degradation

Previous studies from our research group have suggested that procyanidins modify glycemia and insulinemia. The aim of this work was to evaluate the effects of procyanidins on β-cell functionality in a nonpathological system. Four groups of healthy rats were studied. The animals were given daily acute doses of grape seed procyanidin extract (GSPE) for different time periods and at different daily amounts. A β-cell line (INS-1E) was treated with 25 mg GSPE/L for 24 h to identify possible mechanisms of action for the procyanidins. In vivo experiments showed that different doses of GSPE affected insulinemia in different ways by modifying β-cell functionality and/or insulin degradation. The islets isolated from rats that were treated with 25 mg GSPE/kg of body weight for 45 days exhibited a limited response to glucose stimulation. In addition, insulin gene expression, insulin synthesis and expression of genes related to insulin secretion were all down-regulated. In vitro studies revealed that GSPE decreased the ability of β-cells to secrete insulin in response to glucose. GSPE increased glucose uptake in β-cells under high-glucose conditions but impaired glucose-induced mitochondrial hyperpolarization, decreased adenosine triphosphate (ATP) synthesis and altered cellular membrane potentials. GSPE also modified Glut2, glucokinase and Ucp2 gene expression as well as altered the expression of hepatic insulin-degrading enzyme (Ide), thereby altering insulin degradation. At some doses, procyanidins changed β-cell functionality by modifying insulin synthesis, secretion and degradation under nonpathological conditions. Membrane potentials and Ide provide putative targets for procyanidins to induce these effects.

Preventive and improvement effects of exercise training and supplement intake in white adipose tissues on obesity and lifestyle-related diseases

Recent increases in the number of obese individuals and individuals suffering from lifestyle-related diseases, such as type 2 diabetes, that accompany obesity have become a serious social problem. White adipose tissue (WAT) is more than a mere organ for storage of energy; it is also a highly active metabolic and endocrine organ that secretes physiologically active substances collectively known as adipokines, including tumor necrosis factor-α and adiponectin. Dysregulated expression of adipokines in WAT that is hypertrophied by obesity has been closely associated with the phenomenon of insulin resistance. Therefore, WAT is currently considered to be one of the tissues that promote lifestyle-related diseases. Reduction of excess WAT that results from obesity is seen as an important strategy in preventing and improving lifestyle-related diseases. This review shows that exercise training as well as intake of supplements, such as polyphenols, is one strategy for this, because this regimen can result in reduction of WAT mass, which affects the expression and secretory response of adipokines.

Moderate effects of apple juice consumption on obesity-related markers in obese men: impact of diet-gene interaction on body fat content

PURPOSE

The effect of polyphenol-rich cloudy apple juice (CloA) consumption on plasma parameters related to the obesity phenotype and potential effects of interactions between CloA and allelic variants in obesity candidate genes were assessed in obese men.

METHODS

In this controlled, randomized, and parallel study, n = 68, non-smoking, non-diabetic men with a BMI ≥27 kg/m(2) received 750 mL/day CloA (802.5 mg polyphenols) or 750 mL/day control beverage (CB, isocaloric equivalent to CloA) for 4 weeks. Further, study participants were genotyped for single-nucleotide polymorphisms in PPARγ (rs1801282), UCP3 (rs1800849), IL-6 (rs1800795), FABP2 (rs1799883), INSIG2 (rs7566605), and PGC1 (rs8192678) genes. At the beginning and at the end of intervention plasma lipids, distinct adipokines and cytokines as well as anthropometric parameters were determined.

RESULTS

CloA compared to CB had no significant effect on plasma lipids, plasma adipokine and cytokine levels, BMI, and waist circumference. However, CloA consumption significantly reduced percent body fat compared to CB (∆ % body fat: CloA: -1.0 ± 1.3 vs. CB: -0.2 ± 0.9, p < 0.05). The IL-6-174 G/C polymorphism showed an interaction with body fat reduction induced by CloA. Solely in C/C, but not in G/C or G/G variants, a significant reduction in body fat after 4 weeks of CloA intervention was detectable.

CONCLUSION

The observed diet-gene interaction might be a first indication for the impact of individual genetic background on CloA-mediated bioactivity on obesity-associated comorbidities.

(-)-Epigallocatechin-3-gallate blocks 3T3-L1 adipose conversion by inhibition of cell proliferation and suppression of adipose phenotype expression

AIMS

A major objective in the treatment of obese individuals is the development of agents that reduce body fat and improve metabolic homeostasis. Among a variety of biological effects, green tea exerts an anti-obesity effect; however, the mechanisms behind its activity on adipose tissue are uncertain. Tea contains high levels of (-)-epigallocatechin-3-gallate (EGCG), which is one of its main bioactive substances. Therefore, we studied the effects of EGCG on mouse embryonic fibroblast-adipose like cell line (3T3-L1) preadipocyte proliferation and differentiation.

MAIN METHODS

3T3-L1 cells were incubated with physiologically attainable (0.1-1 μM) and pharmacological (5μM, 10μM) concentrations of EGCG for various lengths of time. Cell proliferation was assessed by cell counting and cell cycle analysis. Adipose conversion was evaluated by lipid accumulation and expression of CCAAT/enhancer binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ) transcription factors.

KEY FINDINGS

A dose dependent suppressive effect on preadipocyte proliferation was observed, with the highest reduction in cell number at 10μM EGCG. On the other hand, adipose conversion was fully inhibited with 10μM EGCG. Flow-cytometric analysis showed that 3T3-L1 cells treated with EGCG underwent an arrest of cell cycle at G2/M. The inhibition of the expression of C/EBPα and PPARγ was accompanied by the inhibitory effect of EGCG. Microscopic observation showed that 3T3-L1 cells treated with EGCG maintained the fibroblastic shape and failed to accumulate cytoplasmic fat droplets even after the induction of differentiation.

SIGNIFICANCE

Our results suggest that EGCG reduces adipogenesis through an arrest of cell cycle and a blockage of adipose phenotype expression. These results also suggest that the anti-obesity activity of green tea may be partially attributed to its suppressive effects in adipogenesis.