Effects of (-)-epicatechin on a diet-induced rat model of cardiometabolic risk factors

A pilot study on clinical pharmacokinetics and preclinical pharmacodynamics of (+)-epicatechin on cardiometabolic endpoints

We reported that (-)-epicatechin can stimulate mitochondria biogenesis and improve metabolism. However, preliminary studies indicate that the (+) stereoisomer form may be more potent. We evaluated in a preliminary manner, the pharmacokinetics (PK) and initial safety analysis of (+)-epicatechin ((+)-Epi) in healthy and pre-diabetic subjects. Using a mouse model of diet-induced obesity and insulin resistance, we also evaluated the metabolic effects of (+)-Epi vs. (+)-catechin (Cat) to determine class effects. In the Phase I PK study, subjects were provided a single incremental oral dose of (+)-Epi (10, 30 or 100 mg). For the PD study, subjects were provided a single 30 mg dose per day for 7 days. Blood samples were collected and safety measures were performed. Incremental doses of (+)-Epi increase the half-life of blood metabolites from 1.2-4.9 h. The compound was well tolerated and no adverse effects were reported. Seven day dosing of pre-diabetic subjects led to tendencies for reductions in circulating levels of tumor necrosis factor-α and monocyte chemoattractant protein-1, which returned to baseline by 7 days after treatment. In animals, 2 weeks of oral dosing (0.003, 0.01, 0.03, 0.1 and 0.3 mg kg-1 day-1) dose dependently improved metabolism-related endpoints (weight gain, glucose, cholesterol, triglyceride, with thresholds as low as 0.01 mg kg-1 day-1). Cat yielded no effects at 0.1 mg kg-1 day-1. Results indicate that (+)-Epi evidences a favorable PK and safety profile. Using a pre-clinical model, the compound positively modulates metabolism, which may link to mitochondrial effects. Effects are not due to general antioxidant actions, as Cat yielded no effects.

Dietary (Poly)phenols, Brown Adipose Tissue Activation, and Energy Expenditure: A Narrative Review

The incidence of overweight and obesity has reached epidemic proportions, making the control of body weight and its complications a primary health problem. Diet has long played a first-line role in preventing and managing obesity. However, beyond the obvious strategy of restricting caloric intake, growing evidence supports the specific antiobesity effects of some food-derived components, particularly (poly)phenolic compounds. The relatively new rediscovery of active brown adipose tissue in adult humans has generated interest in this tissue as a novel and viable target for stimulating energy expenditure and controlling body weight by promoting energy dissipation. This review critically discusses the evidence supporting the concept that the antiobesity effects ascribed to (poly)phenols might be dependent on their capacity to promote energy dissipation by activating brown adipose tissue. Although discrepancies exist in the literature, most in vivo studies with rodents strongly support the role of some (poly)phenol classes, particularly flavan-3-ols and resveratrol, in promoting energy expenditure. Some human data currently are available and most are consistent with studies in rodents. Further investigation of effects in humans is warranted.

(-)-Epicatechin regulates blood lipids and attenuates hepatic steatosis in rats fed high-fat diet

SCOPE

(-)-Epicatechin (EC) is a natural flavanol monomer found in cocoa, green tea, and a variety of other plant foods. In this study, effects of EC on blood lipids and hepatic steatosis, and the underlying mechanisms were investigated.

METHODS AND RESULTS

A hyperlipidemic rat model was induced by high-fat, high-cholesterol diet. EC was then administrated to the animals by gavage at doses of 10, 20, 40 mg/kg body weight (BW) for 12 weeks. Simvastatin was included as a positive control. The results showed that EC significantly reduced total cholesterol, LDL cholesterol and triglyceride, alleviated liver fat accumulation, while increased HDL cholesterol, in hyperlipidemic rats. EC also reduced lipid peroxidation, inhibited the pro-inflammatory cytokines, and lowered serum AST and ALT. The potential molecular mechanisms of EC underlying these effects were proposed to be associated to regulating Insig-1-SREBP-SCAP pathway, and other lipid metabolic related genes including LXR-α, FAS, and SIRT1.

CONCLUSION

EC effectively improved blood lipid profile and protected liver from accumulating excessive fat in hyperlipidemic rats. The results shed a light on the potential role of EC as a promising natural product in preventing hyperlipidemia and nonalcoholic fatty liver disease.

Browning effects of (-)-epicatechin on adipocytes and white adipose tissue

In this study, we demonstrate that (-)-epicatechin (Epi), a cacao flavanol, induces the browning of fat by promoting mitochondrial biogenesis, enhancing indicators of mitochondrial structure and function, increasing fatty acid metabolism and upregulating the expression of brown adipose tissue-specific proteins in a high-fat diet mouse model of obesity and in cultured human adipocytes. Epi treatment significantly improved mitochondrial function, as measured by citrate synthase activity, and also reduced protein acetylation of total and specific regulators in both adipose tissue and human adipocytes. Browning of fat via Epi was evidenced by the increased expression of key thermogenic genes, phosphorylation of upstream regulators of fatty acid oxidation, and reduced triglyceride levels. Properly designed clinical trials are needed to explore the potential of Epi as an agent that promotes the browning of fat.

Phenyl-γ-valerolactones, flavan-3-ol colonic metabolites, protect brown adipocytes from oxidative stress without affecting their differentiation or function

SCOPE

Consumption of products rich in flavan-3-ols, such as tea and cocoa, has been associated with decreased obesity, partially dependent on their capacity to enhance energy expenditure. Despite these phenolics having been reported to increase the thermogenic program in brown and white adipose tissue, flavan-3-ols are vastly metabolised in vivo to phenyl-γ-valerolactones. Therefore, we hypothesize that phenyl-γ-valerolactones may directly stimulate the differentiation and the activation of brown adipocytes.

METHODS AND RESULTS

Immortalized brown pre-adipocytes were differentiated in presence of (R)-5-(3',4'-dihydroxyphenyl)-γ-valerolactone (VL1), (R)-5-(3´-hydroxyphenyl)-γ-valerolactone-4'-O-sulphate (VL2), (R)-5-phenyl-γ-valerolactone-3´,4´-di-O-sulphate (VL3), at concentrations of 2 or 10μM, whereas fully differentiated brown adipocyte were treated acutely (6-24h). None of the treatments regulated the expression levels of the uncouple protein 1, nor of the main transcription factors involved in brown adipogenesis. Similarly, mitochondrial content was unchanged after treatments. Moreover these compounds did not display peroxisome proliferator-activated receptor γ-agonist activity, as evaluated by luciferase assay, and did not enhance norepinephrine-stimulated lipolysis in mature adipocytes. However, both VL1 and VL2 prevented oxidative stress caused by H₂ O₂ .

CONCLUSION

Phenyl-γ-valerolactones and their sulphated forms do not influence brown adipocyte development or function at physiological or supraphysiological doses in vitro, but they are active protecting brown adipocytes from increased reactive oxygen species production.

Phenolic-rich lychee (Litchi chinensis Sonn.) pulp extracts offer hepatoprotection against restraint stress-induced liver injury in mice by modulating mitochondrial dysfunction

The pulp from lychee, a tropical to subtropical fruit, contains large quantities of phenolic compounds and exhibits antioxidant activities both in vitro and in vivo. In the present study, we investigated the mechanisms underlying the hepatoprotective effects of lychee pulp phenolics (LPPs) against restraint stress-induced liver injury in mice. After 18 h of restraint stress, increased levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were observed. High levels of thiobarbituric acid reactive substances (TBARS) were also found. Restraint stress causes liver damage, which was protected against by LPP pretreatment at a dosage of 200 mg (kg d)(-1) for 21 consecutive days. This treatment remarkably decreased the serum ALT, AST and TBARS levels, elevated the liver glutathione (GSH) content, and the activities of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT). Furthermore, respiratory chain complex and Na(+)-K(+)-ATPase activities were enhanced in liver mitochondria, while mitochondrial membrane potential levels and reactive oxygen species (ROS) production decreased. Thus, treatment with LPPs ameliorated restraint stress-induced liver mitochondrial dysfunction. These results suggest that LPPs protect the liver against restraint stress-induced damage by scavenging free radicals and modulating mitochondrial dysfunction. Thus, lychee pulp may be a functional biofactor to mitigate oxidative stress.

Epicatechin, procyanidins, cocoa, and appetite: a randomized controlled trial

BACKGROUND

In 2 randomized controlled trials, it was reported that dark chocolate acutely decreased appetite in human subjects, but the authors did not assess the types or concentrations of cocoa compounds that are needed. Other studies have suggested that the cocoa compounds epicatechin and procyanidins may be involved.

OBJECTIVE

We sought to test the hypotheses that, compared with placebo (an alkalized cocoa mixture containing essentially no epicatechin or procyanidins), the following beverages cause a decrease in appetite: 1) a nonalkalized cocoa mixture; 2) epicatechin plus placebo; and 3) procyanidins plus placebo. We measured the concentrations of cocoa compounds in all beverages.

DESIGN

We used a 4-way randomized, crossover, placebo-controlled trial that was balanced for period and carryover effects in 28 healthy, young-adult men. We also conducted a smaller (n = 14), parallel, secondary randomized trial in which we explored the effects of higher doses of epicatechin and procyanidins. Our primary measure of appetite was ad libitum pizza intake 150 min after beverage ingestion. We used a linear mixed-model analysis.

RESULTS

Intakes of beverages with the nonalkalized cocoa mixture that contained 0.6 mg epicatechin, 0.2 mg catechin, and 2.9 mg monomer-decamer procyanidins/kg body weight did not decrease pizza intake significantly (P = 0.29) compared with intake of the placebo. In the smaller secondary trial, a combination of epicatechin and the nonalkalized cocoa mixture that contained 1.6 mg epicatechin/kg body weight significantly decreased pizza intake by 18.7% (P = 0.04).

CONCLUSIONS

Our nonalkalized cocoa mixture was associated with an acute decrease in food intake only after being supplemented with epicatechin. It is possible that epicatechin at a dose of >1.6 mg/kg body weight, alone or in concert with appropriate catalytic cocoa compounds, may be useful for helping people control their food intakes. This trial was registered at clinicaltrials.gov as NCT02408289.

A randomized, placebo-controlled, double-blind study on the effects of (-)-epicatechin on the triglyceride/HDLc ratio and cardiometabolic profile of subjects with hypertriglyceridemia: Unique in vitro effects

BACKGROUND

Cardiometabolic disruptions such as insulin resistance, obesity, high blood pressure, hyperglycemia, and dyslipidemias, are known to increase the risk for cardiovascular and metabolic diseases such as type 2 diabetes mellitus and atherosclerosis. Several screening tools for assessing cardiometabolic risk have been developed including the TG/HDLc ratio, which has been, demonstrated to possess a strong association with insulin resistance and coronary disease. Dietary modifications, together with regular moderate exercise have proven to be effective in attenuating cardiometabolic disruptions. However, they often exhibit poor long-term patient compliance. Nutraceutics, including (-)-epicatechin (EPI), have gained increasing interest as coadjuvant effective and safe therapies that are able to attenuate hypertension, hyperglycemia, hyperinsulinemia, hypertriglyceridemia and hypoalphalipoproteinemia.

METHODS

The aims of this study were: 1) to compare the in vitro effect of EPI vs. (+)-catechin on fructose induced triglyceride accumulation and mitochondrial function in Hep2 cells in culture, 2) to evaluate the efficacy of EPI treatment in reducing fasting blood triglycerides and improving the TG/HDLc ratio in hypertriglyceridemic patients with a total daily dose of 100mg of EPI. Secondary clinical variables included total cholesterol, LDLc, fructosamine, glucose, insulin, and high sensitivity C-reactive protein blood levels.

RESULTS AND CONCLUSION

Our results provide preliminary evidence as to favorable effects of EPI on glycemia homeostasis, lipid profile and systemic inflammation such bioactive actions are not class-effects (i.e. limited to their antioxidant potential) but instead, may result from the specific activation of associated downstream signaling pathways since catechin has no effects.

(-)-Epicatechin in vitro ameliorates erythrocyte protein carbonyl content in hypertensive patients: comparison with L-ascorbic acid

CONTEXT

Oxidative stress plays a key role in the patho-physiology of hypertension. (-)-Epicatechin has many important biological properties.

OBJECTIVE

The present study was undertaken to evaluate effect of (-)-epicatechin on protein carbonyl content in gender-based hypertensive patients and normal subjects.

METHODS

The study was carried out on 83 normal (male: 42; female: 41) and 62 hypertensive subjects (male: 32; female: 30). In vitro effect on (-)-epicatechin and L-ascorbic acid was estimated on protein carbonyl content.

RESULTS

Result showed a significant (p < 0.001) increase in protein carbonyl content in hypertensive patients but no gender-based difference was observed. (-)-epicatechin shows significant (p < 0.001) dose-dependent effect as compared to L-ascorbic acid, which is manifested as decrease in protein carbonyl content.

CONCLUSION

We hypothesizes that a higher intake of (-)-epicatechin may provide protection against hypertension in males and females.

Effects of Anthocyanin and Flavanol Compounds on Lipid Metabolism and Adipose Tissue Associated Systemic Inflammation in Diet-Induced Obesity

Background. Naturally occurring substances from the flavanol and anthocyanin family of polyphenols have been proposed to exert beneficial effects in the course of obesity. We hypothesized that their effects on attenuating obesity-induced dyslipidemia as well as the associated inflammatory sequelae especially have health-promoting potential. Methods. Male C57BL/6J mice (n = 52) received a control low-fat diet (LFD; 10 kcal% fat) for 6 weeks followed by 24 weeks of either LFD (n = 13) or high-fat diet (HFD; 45 kcal% fat; n = 13) or HFD supplemented with 0.1% w/w of the flavanol compound epicatechin (HFD+E; n = 13) or an anthocyanin-rich bilberry extract (HFD+B; n = 13). Energy substrate utilization was determined by indirect calorimetry in a subset of mice following the dietary switch and at the end of the experiment. Blood samples were collected at baseline and at 3 days and 4, 12, and 20 weeks after dietary switch and analyzed for systemic lipids and proinflammatory cytokines. Adipose tissue (AT) histopathology and inflammatory gene expression as well as hepatic lipid content were analyzed after sacrifice. Results. The switch from a LFD to a HFD lowered the respiratory exchange ratio and increased plasma cholesterol and hepatic lipid content. These changes were not attenuated by HFD+E or HFD+B. Furthermore, the polyphenol compounds could not prevent HFD-induced systemic rise of TNF-α levels. Interestingly, a significant reduction in Tnf gene expression in HFD+B mice was observed in the AT. Furthermore, HFD+B, but not HFD+E, significantly prevented the early upregulation of circulating neutrophil chemoattractant mKC. However, no differences in AT histopathology were observed between the HFD types. Conclusion. Supplementation of HFD with an anthocyanin-rich bilberry extract but not with the flavanol epicatechin may exert beneficial effects on the systemic early inflammatory response associated with diet-induced obesity. These systemic effects were transient and not observed after prolongation of HFD-feeding (24 weeks). On the tissue level, long-term treatment with bilberry attenuated TNF-α expression in adipose tissue.

(-)-Epicatechin-induced recovery of mitochondria from simulated diabetes: Potential role of endothelial nitric oxide synthase

(-)-Epicatechin increases indicators associated with mitochondrial biogenesis in endothelial cells and myocardium. We investigated endothelial nitric oxide synthase involvement on (-)-epicatechin-induced increases in indicators associated with mitochondrial biogenesis in human coronary artery endothelial cells cultured in normal-glucose and high-glucose media, as well as to restore indicators of cardiac mitochondria from the effects of simulated diabetes. Here, we demonstrate the role of endothelial nitric oxide synthase on (-)-epicatechin-induced increases in mitochondrial proteins, transcription factors and sirtuin 1 under normal-glucose conditions. In simulated diabetes endothelial nitric oxide synthase function, mitochondrial function-associated and biogenesis-associated indicators were adversely impacted by high glucose, effects that were reverted by (-)-epicatechin. As an animal model of type 2 diabetes, 2-month old C57BL/6 mice were fed a high-fat diet for 16 weeks. Fasting and fed blood glucose levels were increased and NO plasma levels decreased. High-fat-diet-fed mice myocardium revealed endothelial nitric oxide synthase dysfunction, reduced mitochondrial activity and markers of mitochondrial biogenesis. The administration of 1 mg/kg (-)-epicatechin for 15 days by oral gavage shifted these endpoints towards control mice values. Results suggest that endothelial nitric oxide synthase mediates (-)-epicatechin-induced increases of indicators associated with mitochondrial biogenesis in endothelial cells. (-)-Epicatechin also counteracts the negative effects that high glucose or simulated type 2 diabetes has on endothelial nitric oxide synthase function.

(-)-Epicatechin improves insulin sensitivity in high fat diet-fed mice

Obesity constitutes a major public health concern, being frequently associated with type 2 diabetes (T2D). Evidence from studies in humans and experimental animals suggest that consumption of the flavan-3-ol (-)-epicatechin (EC) and of EC-rich foods may improve insulin sensitivity. To further understand the potential benefits of dietary EC consumption on insulin resistance, this study investigated the capacity of EC supplementation to prevent high fat diet (HFD)-induced insulin resistance in mice. To assess the underlying mechanisms, the effects of HFD and EC consumption on the activation of the insulin cascade and of its negative modulators were evaluated. HFD consumption for 15 w caused obesity and insulin resistance in C57BL/6J mice as evidenced by high fasted and fed plasma glucose and insulin levels, and impaired ITT and GTT tests. This was associated with alterations in the activation of components of the insulin-triggered signaling cascade (insulin receptor, IRS1, ERK1/2, Akt) in adipose and liver tissues. EC supplementation prevented/ameliorated all these parameters. EC acted improving insulin sensitivity in the HFD-fed mice in part through a downregulation of the inhibitory molecules JNK, IKK, PKC and protein tyrosine phosphatase 1B (PTP1B). Thus, the above results suggest that consumption of EC-rich foods could constitute a dietary strategy to mitigate obesity-associated insulin resistance.

Mechanisms by which cocoa flavanols improve metabolic syndrome and related disorders

Dietary administration of cocoa flavanols may be an effective complementary strategy for alleviation or prevention of metabolic syndrome, particularly glucose intolerance. The complex flavanol composition of cocoa provides the ability to interact with a variety of molecules, thus allowing numerous opportunities to ameliorate metabolic diseases. These interactions likely occur primarily in the gastrointestinal tract, where native cocoa flavanol concentration is high. Flavanols may antagonize digestive enzymes and glucose transporters, causing a reduction in glucose excursion, which helps patients with metabolic disorders maintain glucose homeostasis. Unabsorbed flavanols, and ones that undergo enterohepatic recycling, will proceed to the colon where they can exert prebiotic effects on the gut microbiota. Interactions with the gut microbiota may improve gut barrier function, resulting in attenuated endotoxin absorption. Cocoa may also positively influence insulin signaling, possibly by relieving insulin-signaling pathways from oxidative stress and inflammation and/or via a heightened incretin response. The purpose of this review is to explore the mechanisms that underlie these outcomes, critically review the current body of literature related to those mechanisms, explore the implications of these mechanisms for therapeutic utility, and identify emerging or needed areas of research that could advance our understanding of the mechanisms of action and therapeutic potential of cocoa flavanols.