A diet rich in cocoa attenuates N-nitrosodiethylamine-induced liver injury in rats

Cocoa seeds and chocolate products interaction with gut microbiota; mining microbial and functional biomarkers from mechanistic studies, clinical trials and 16S rRNA amplicon sequencing

In recent years, gut microbiome has evolved as a focal point of interest with growing recognition that a well-balanced gut microbiota is highly relevant to an individual's health status. The present review provides a mechanistic insight on the effects of cocoa chemicals on the gut microbiome and further reveals in silico biomarkers, taxonomic and functional features that distinguish gut microbiome of cocoa consumers and controls by using 16S rRNA gene sequencing data. The polyphenols in cocoa can change the gut microbiota either by inhibiting the growth of pathogenic bacteria in the gut such as Clostridium perfringens or by increasing the growth of beneficial microbiota in the gut such as Lactobacillus and Bifidobacterium. This paper demonstrates the holistic effect of gut microbiota on cocoa chemicals and how it impacts human health. We present herein the first comprehensive review and analysis of how raw and roasted cocoa and its products can specifically influence gut homeostasis, and likewise, how microbiota metabolizes cocoa chemicals. In addition to that, our 16S rRNA amplicon sequencing analysis revealed that the flavone and flavonols metabolism, aminobenzoate degradation and fatty acid elongation pathways represent the three most important signatures of microbial functions associated with cocoa consumption.

Cacao powder supplementation attenuates oxidative stress, cholinergic impairment, and apoptosis in D-galactose-induced aging rat brain

Aging, a critical risk factor of several diseases, including neurodegenerative disorders, affects an ever-growing number of people. Cacao supplementation has been suggested to improve age-related neuronal deficits. Therefore, this study investigated the protective effects of raw cacao powder on oxidative stress-induced aging. Male Sprague-Dawley rats were divided into 4 groups: Control (C), D-galactose-induced aging (G), D-galactose injection with 10% (LC), and 16% (HC) cacao powder mixed diet. D-galactose (300 mg/3 mL/kg) was intraperitoneally injected into all but the control group for 12 weeks. Cacao supplemented diets were provided for 8 weeks. The levels of serum Malondialdehyde (MDA), Advanced Glycation End-products (AGEs), brain and liver MDA, the indicators of the D-galactose induced oxidative stress were significantly decreased in LC and HC but increased in G. The Acetylcholinesterase (AChE) activity of brain showed that the cholinergic impairment was significantly lower in LC, and HC than G. Furthermore, the expression levels of catalase (CAT), phospho-Akt/Akt, and procaspase-3 were significantly increased in LC and HC. In conclusion, cacao consumption attenuated the effects of oxidative stress, cholinergic impairment and apoptosis, indicating its potential in future clinical studies.

Proteomic and molecular evidences of Il1rl2, Ric8a, Krt18 and Hsp90b1 modulation during experimental hepatic fibrosis and pomegranate supplementation

The inspection of variations in the proteomic aspects conspire the biomarker discovery in diagnostics of peculiar diseases. Recent developments in high-throughput proteomic techniques have provided leverage in the discovery of biomarkers during the etiology of various diseases. We identified potential biomarkers by utilizing proteomics, bioinformatics and gene expression studies. Meticulous assessment of collagen and hydroxyproline levels along with the glycogen and protein carbonyl levels exhibited deterioration in the N' - Nitrosodiethylamine (NDEA) administered rat livers and subsequent salubrious effect of pomegranate juice. The immunohistochemical inspection of iNOS and nitrite estimation indicated the peccant fibrotic alterations. 2D proteome profiling and MALDI-TOF MS/MS furthered the significant biomarkers to be analyzed for the gene ontology by PANTHER, cluster analysis by DAVID and network simulation by STRING 10.0. Several genes found relevant after MALDI analysis were evaluated by real-time PCR (RTPCR). Our data revealed CYP2b15, HSP70, TRFE, HPT, Il1rl2, Ric8a, Krt18, Hsp90b1 and iNOS as novel biomarkers for the mechanism of pomegranate against liver fibrosis. It can be inferred that NDEA-induced liver fibrosis actuates various biological pathways by the identified biomarkers and pomegranate juice modifies them.

Cisplatin-conjugated gold nanoparticles-based drug delivery system for targeting hepatic tumors

Cisplatin is a highly cytotoxic anticarcinogenic drug used to treat several kinds of solid tumors such as liver tumors. With the increase in the incidences associated with hepatic tumors and a lack of selectivity of cisplatin to cancer cells, it is important to explore new therapeutic strategies against them. The present study was designed to verify the ability of gold nanoparticles (GNPs) to improve the hepatotherapeutic effect of cisplatin against DENA-induced hepatic tumors and to declare its ability to reduce the renal toxicity induced by cisplatin. Forty male Wistar rats were divided into two groups (n = 20): Group (A)-negative control and group (B)-model of hepatocellular tumor induction. After 4 months, each group was subdivided into four subgroups as the following: Group (1) received normal saline, Group (2) was treated by cisplatin, Group (3) was treated by GNPs, Group (4) was treated by GNPs-cisplatin conjugates. Our results revealed a marked elevation in liver and kidney function tests and oxidant levels with a reduction in antioxidant levels in the DENA-administrated group. Remarkable histopathological alterations in the liver and kidney tissue sections were observed and confirmed by the overexpression of the immunohistochemical staining of placental glutathione S-transferase, Hep Par 1, and proliferating cell nuclear antigen. Noticeable improvements in all the measurable toxicological parameters were recorded in the group treated with either GNPs or GNPs-cisplatin conjugate not observed in the group treated with cisplatin. We can conclude that GNPs not only improve the distribution of cisplatin, targeting it to the site of tumors, but it also reduces the renal toxicity induced by cisplatin, which are the primary concerns in cancer therapy.

Immunohistochemical and biochemical alterations following administration of proanthocyanidin extract in rats hepatocellular carcinoma

Grape seed proanthocyanidin extract (GSPE) is known to be effective on broad spectrum of biological pathways in living organisms including oxidative stress. The present study aimed to investigate the effects of proanthocyanidin on preneoplastic lesions and liver cancer induced in rats by Diethylnitrosamine (DEN). 7-8 Week old male Sprague Dawley (S.D.) rats were divided into six groups: The 1st group received no treatment and were -ve controls, the 2nd were treated with a single dose of DEN 200mg/kg intraperitoneally (i.p.) and served as +ve control group. The 3rd and 4th groups were injected with the same dose of DEN as in group 2 and then post treated with 300 or 150mg/kg/b.wt./day GSPE by intrgastroluminal gavage (i.g.) respectively until the end after the 22 weeks. Groups 5 and 6 were treated with the same doses of GSPE as in groups 3 and 4 respectively without DEN administration. The results showed that the immunohistochemical Proliferating Cell Nuclear Antigen (PCNA) labeling indexes (PCNA LI%) were significantly inhibited in liver tissues and tumors by both treatments of GSPE. Furthermore, treatment with GSPE has modified the liver tissue oxidative stress markers levels of SOD, CAT, GSH, GST, GPx, GR and MDA changed by DEN. In conclusion, GSPE has a sufficient therapeutic effect against liver carcinogenesis through their free radical scavenging, inhibition of cellular proliferation.

Therapeutic role of a synthesized calcium phosphate nanocomposite material on hepatocarcinogenesis in rats

Nanotechnology research is booming worldwide, and the general belief is that medical and biological applications will form the greatest sector of expansion over the next decade. With this in mind, this study was designed to evaluate the therapeutic effects of a synthesized tricalcium phosphate nanocomposite material (nano-TCP) on hepatocarcinoma in a rat model, as initiated with diethylnitrosamine (DEN) and promoted with phenobarbital (PB). Hepatocarcinoma was induced with intraperitoneal injections of DEN (50 mg·(kg body mass)(-1)) 3 times a week for 2 weeks. Three weeks after the last dose of DEN, the rats received PB (0.05 %, w/v) in their drinking water for a further 6 weeks. Nano-TCP (100 mg·(kg body mass)(-1)) was administered intraperitoneally 3 times per week to rats with HCC. At the end of the experimental period, liver samples were collected from all animals for biochemical and histopathological analysis. The degree of DNA fragmentation was analyzed, in addition to immune status, by measuring the levels of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukin-2 (IL-2). The activities of the most important free-radical scavengers of the antioxidant defense system as well as malondialdehyde (MDA) content and liver enzymes were measured. The levels of hepatic heat shock protein-70 (HSP-70), caspase-3, and metalloproteinase-9 were also measured as markers for inflammation and apoptosis. Histopathological examination of liver tissue was performed. The results revealed the potent efficacy of nano-TCP in repairing the fragmented DNA and ameliorating most of the investigated parameters by significant elevation in the levels of hepatic alanine aminotransferase (ALT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) activities. On the other hand, there was a significant decrease in hepatic gamma-glutamyl transpeptidase (γ-GT), MDA, IL-2, IFN-γ, TNF-α, matrix metalloproteinase-9 (MMP-9), HSP-70, and caspase-3 levels upon treatment. The findings form histopathological examination of the liver tissues agreed with the biochemical results and confirmed the difference between the control and treatment groups. In conclusion, nano-TCP succeeded in treating hepatocarcinoma efficiently, and presents a new hope for patients to get safe, fast, and effective treatment.

Antiproliferative and cytotoxic effects of green coffee and yerba mate extracts, their main hydroxycinnamic acids, methylxanthine and metabolites in different human cell lines

This work aimed at studying the effects of green coffee bean (GCBE) and yerba mate (YME) extracts, their main phenolic components (5-caffeoylquinic acid, 5-CQA; 3,5-dicaffeoylquinic acid, 3,5-DCQA) and metabolites (ferulic acid, FA; caffeic acid, CA; dihydrocaffeic acid, DHCA; and dihydroferulic acid, DHFA) along with caffeine (CAF) on the viability and proliferation of different human cell lines. Extracts (10-1000 μg/mL) and standards (10-1000 μM) were assayed in colon (Caco-2), lung (A549), oesophageal (OE-33), urinary bladder (T24) human carcinoma cells, and a non-cancer cell line (CCD-18Co). YME significantly reduced viability of cancer cells at all assayed concentrations, the higher doses also reducing cell proliferation. GCBE effects on cell viability were more effective at 100 and 1000 μg/mL, showing modest effects on cell proliferation. The highest doses of 5-CQA and 3,5-DCQA reduced cell viability and proliferation in all cell lines, whereas FA, DHCA and DHFA had lower and variable effects. Caffeine had no effect. Dietary-attainable concentrations (0.1, 1 and 10 μg/mL) of YME were tested for cytotoxicity and reactive oxygen species generation, showing no cytotoxic effect. Low concentrations of all tested compounds were non-cytotoxic to CCD-18Co cells.

CONCLUSION

YME and to a lower degree GCBE, their phenolic components and metabolites may decrease cancer cell viability and proliferation.

Vochysia rufa Stem Bark Extract Protects Endothelial Cells against High Glucose Damage

Background: Increased oxidative stress by persistent hyperglycemia is a widely accepted factor in vascular damage responsible for type 2 diabetes complications. The plant Vochysia rufa (Vr) has been used in folk medicine in Brazil for the treatment of diabetes. Thus; the protective effect of a Vr stem bark extract against a challenge by a high glucose concentration on EA.hy926 (EA) endothelial cells is evaluated. Methods: Vegetal material is extracted with distilled water by maceration and evaporated until dryness under vacuum. Then; it is isolated by capillary electrophoresis-tandem mass spectrometry. Cell viability is evaluated on EA cells treated with 0.5-100 µg/mL of the Vr extract for 24 h. The extract is diluted at concentrations of 5, 10 and 25 µg/mL and maintained for 24 h along with 30 mM of glucose to evaluate its protective effect on reduced glutathione (GSH); glutathione peroxidase (GPx) and reductase (GR) and protein carbonyl groups. Results:V. rufa stem bark is composed mainly of sugars; such as inositol; galactose; glucose; mannose; sacarose; arabinose and ribose. Treatment with Vr up to 100 µg/mL for 24 h did not affect cell viability. Treatment of EA cells with 30 mM of glucose for 24 h significantly increased the cell damage. EA cells treated with 30 mM of glucose showed a decrease of GSH concentration and increased Radical Oxygen Species (ROS) and activity of antioxidant enzymes and protein carbonyl levels; compared to control. Co-treatment of EA with 30 mM glucose plus 1-10 μg/mL Vr significantly reduced cell damage while 5-25 μg/mL Vr evoked a significant protection against the glucose insult; recovering ROS; GSH; antioxidant enzymes and carbonyls to baseline levels. Conclusion:V. rufa extract protects endothelial cells against oxidative damage by modulating ROS; GSH concentration; antioxidant enzyme activity and protein carbonyl levels.

A novel curcumin analogue is a potent chemotherapy candidate for human hepatocellular carcinoma

Curcumin (CUR) has been demonstrated to protect against carcinogenesis and to prevent tumor development in cancer; however, the clinical application of CUR is limited by its instability and poor metabolic properties. The present study offers an strategy for a novel CUR analogue, (1E,4E)-1,5-bis(2-bromophenyl)penta-1,4-dien-3-one (GL63), to be used as a potential therapeutic agent for hepatocellular carcinoma (HCC) in vitro and in vivo. The current study demonstrated that GL63 exhibited more potent inhibition of proliferation of HCC cells than CUR. GL63 induced G0/G1 phase cell cycle arrest and apoptosis in SK-HEP-1 cells in a dose-dependent manner, and was more potent than CUR, according to the flow cytometry data. The present study demonstrated for the first time that the inhibition of the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway by GL63 resulted in a protective effect against HCC cell growth. GL63 was more effective than CUR in regulating STAT3 downstream targets, which contributed to the suppression of cell proliferation and the induction of cell apoptosis. In addition, the effects of GL63 were tested in a model of N-nitrosodiethylamine (DEN)-induced HCC in Wistar rats. Although macroscopic and microscopic features suggested that both GL63 and CUR were effective in inhibiting DEN-induced hepatocarcinogenesis, GL63 exerted a stronger effect than CUR. Immunohistochemical analysis for proliferating cell nuclear antigen demonstrated significant differences among the DEN-bearing non-treated, DEN-bearing GL63-treated and DEN-bearing, CUR-treated groups (P=0.039). It was concluded that GL63 was a potent agent able to suppress the proliferation of HCC cells by inhibition of the JAK2/STAT3 signaling pathway, with more favorable pharmacological activity than CUR, and may be a more potent compound for the prevention of DEN-induced hepatocarcinogenesis in rats than CUR.

Unsweetened Natural Cocoa Powder Has the Potential to Attenuate High Dose Artemether-Lumefantrine-Induced Hepatotoxicity in Non-Malarious Guinea Pigs

Objective. This study investigated the elemental composition of unsweetened natural cocoa powder (UNCP), its effect on nitric oxide, and its hepatoprotective potential during simultaneous administration with high-dose artemether/lumefantrine (A/L). Method. Macro- and microelements in UNCP were analyzed with EDXRF spectroscopy. Thirty (30) male guinea-pigs were then divided into five groups. For groups 3 (low-dose), 4 (medium-dose), and 5 (high-dose), the animals received oral UNCP prophylactically for 14 days. Group 1 received distilled water (14 days) and group 2 A/L for the last 3 days (days 12 to 14). After euthanisation, biochemical and histopathological examinations were carried out in all groups. Results. Phytochemical analysis of UNCP showed the presence of saponins, flavonoids, tannins, and cardiac glycosides. Thirty-eight (38) macro- and microelements were found. UNCP produced significant decreases in ALT, ALP, GGT, and AST levels. A significant increase in total protein levels was observed during A/L+UNCP administration in comparison to 75 mg/kg A/L group. Histopathological examinations buttressed the protective effects of cocoa administration. UNCP administration increased nitric oxide levels 149.71% (P < 0.05) compared to controls. Conclusion. UNCP increases nitric oxide levels and has hepatoprotective potential during A/L administration. A high level of copper was observed which may be detrimental during high daily consumptions of UNCP.

Dietary Cocoa Powder Improves Hyperlipidemia and Reduces Atherosclerosis in apoE Deficient Mice through the Inhibition of Hepatic Endoplasmic Reticulum Stress

Cocoa powder is rich in flavonoids, which have many beneficial effects on human health, including antioxidative and anti-inflammatory effects. The aim of our study was to investigate whether the intake of cocoa powder has any influence on hyperlipidemia and atherosclerosis and examine the underlying molecular mechanisms. We fed apoE knockout mice a Western diet supplemented with either 0.2% (low group) or 2% (high group) cocoa powder for 12 weeks. The groups fed dietary cocoa powder showed a significant reduction in both plasma cholesterol levels and aortic atherosclerosis compared to the control group. Analysis of mRNA profiling of aortic atherosclerotic lesions revealed that the expression of several genes related to apoptosis, lipid metabolism, and inflammation was significantly reduced, while the antiapoptotic gene Bcl2 was significantly increased in the cocoa powder group compared to the control. RT-PCR analysis along with Western blotting revealed that a diet containing cocoa powder inhibited the expression of hepatic endoplasmic reticulum stress. These data suggest that cocoa powder intake improves hyperlipidemia and atherosclerosis, and such beneficial effects are possibly mediated through the suppression of hepatic endoplasmic reticulum stress.

Flavor Chemistry of Cocoa and Cocoa Products-An Overview

Cocoa originates from beans of the cocoa tree (Theobroma cacao L.) and it is an important commodity in the world and the main ingredient in chocolate manufacture. Its value and quality are related to unique and complex flavors. Bulk cocoas (Forastero type) exhibit strong basic cocoa notes, whereas fine varieties (Criollo, Nacional) show aromatic, floral, or smoother flavor characteristics. About 600 various compounds (alcohols, carboxylic acids, aldehydes, ketones, esters, and pyrazines) have been identified as odor-active components. The specific cocoa aroma arises from complex biochemical and chemical reactions during the postharvest processing of raw beans, and from many influences of the cocoa genotype, chemical make-up of raw seeds, environmental conditions, farming practices, processing, and manufacturing stages. There has been much research on cocoa flavor components. However, the relationships between all chemical components that are likely to play a role in cocoa flavor, their sensory properties, and the sources and mechanisms of flavor formation are not fully understood. This paper provides an overview on cocoa flavor from a compositional and a sensory perspective. The nonvolatile and volatile chemical components of cocoa and chocolate flavor, and their sensory properties correlated to the main influences involved in flavor formation, are reviewed.

Cocoa flavonoids protect hepatic cells against high-glucose-induced oxidative stress: relevance of MAPKs

SCOPE

Oxidative stress plays a main role in the pathogenesis of type 2 diabetes mellitus. Cocoa and (-)-epicatechin (EC), a main cocoa flavanol, have been suggested to exert beneficial effects in type 2 diabetes mellitus because of their protective effects against oxidative stress and insulin-like properties. In this study, the protective effect of EC and a cocoa phenolic extract (CPE) against oxidative stress induced by a high-glucose challenge, which causes insulin resistance, was investigated on hepatic HepG2 cells.

METHODS AND RESULTS

Oxidative status, phosphorylated mitogen-activated protein kinases (MAPKs), nuclear factor E2 related factor 2 (Nrf2) and p-(Ser)-IRS-1 expression, and glucose uptake were evaluated. EC and CPE regulated antioxidant enzymes and activated extracellular-regulated kinase and Nrf2. EC and CPE pre-treatment prevented high-glucose-induced antioxidant defences and p-MAPKs, and maintained Nrf2 stimulation. The presence of selective MAPK inhibitors induced changes in redox status, glucose uptake, p-(Ser)- and total IRS-1 levels that were observed in CPE-mediated protection.

CONCLUSION

EC and CPE recovered redox status of insulin-resistant HepG2 cells, suggesting that the functionality in EC- and CPE-treated cells was protected against high-glucose-induced oxidative insult. CPE beneficial effects on redox balance and insulin resistance were mediated by targeting MAPKs.

Cocoa-rich diet attenuates beta cell mass loss and function in young Zucker diabetic fatty rats by preventing oxidative stress and beta cell apoptosis

We have recently shown that cocoa flavanols may have anti-diabetic potential by promoting survival and function of pancreatic beta-cells in vitro. In this work, we investigated if a cocoa-rich diet is able to preserve beta-cell mass and function in an animal model of type 2 diabetes and the mechanisms involved. Our results showed that cocoa feeding during the prediabetic state attenuates hyperglycaemia, reduces insulin resistant, and increases beta cell mass and function in obese Zucker diabetic rats. At the molecular level, cocoa-rich diet prevented beta-cell apoptosis by increasing the levels of Bcl-xL and decreasing Bax levels and caspase-3 activity. Cocoa diet enhanced the activity of endogenous antioxidant defenses, mainly glutathione peroxidase, preventing thus oxidative injury induced by the pre-diabetic condition and leading to apoptosis prevention. These findings provide the first in vivo evidence that a cocoa-rich diet may delay the loss of functional beta-cell mass and delay the progression of diabetes by preventing oxidative stress and beta-cell apoptosis.

Cocoa flavonoids attenuate high glucose-induced insulin signalling blockade and modulate glucose uptake and production in human HepG2 cells

Insulin resistance is the primary characteristic of type 2 diabetes. Cocoa and its main flavanol, (-)-epicatechin (EC), display some antidiabetic effects, but the mechanisms for their preventive activities related to glucose metabolism and insulin signalling in the liver remain largely unknown. In the present work, the preventive effect of EC and a cocoa polyphenolic extract (CPE) on insulin signalling and on both glucose production and uptake are studied in insulin-responsive human HepG2 cells treated with high glucose. Pre-treatment of cells with EC or CPE reverted decreased tyrosine-phosphorylated and total levels of IR, IRS-1 and -2 triggered by high glucose. EC and CPE pre-treatment also prevented the inactivation of the PI3K/AKT pathway and AMPK, as well as the diminution of GLUT-2 levels induced by high glucose. Furthermore, pre-treatment of cells with EC and CPE avoided the increase in PEPCK levels and the diminished glucose uptake provoked by high glucose, returning enhanced levels of glucose production and decreased glycogen content to control values. These findings suggest that EC and CPE improved insulin sensitivity of HepG2 treated with high glucose, preventing or delaying a potential hepatic dysfunction through the attenuation of the insulin signalling blockade and the modulation of glucose uptake and production.

Cocoa phenolic extract protects pancreatic beta cells against oxidative stress

Diabetes mellitus is associated with reductions in glutathione, supporting the critical role of oxidative stress in its pathogenesis. Antioxidant food components such as flavonoids have a protective role against oxidative stress-induced degenerative and age-related diseases. Flavonoids constitute an important part of the human diet; they can be found in most plant foods, including green tea, grapes or cocoa and possess multiple biological activities. This study investigates the chemo-protective effect of a cocoa phenolic extract (CPE) containing mainly flavonoids against oxidative stress induced by tert-butylhydroperoxide (t-BOOH) on Ins-1E pancreatic beta cells. Cell viability and oxidative status were evaluated. Ins-1E cells treatment with 5–20 μg/mL CPE for 20 h evoked no cell damage and did not alter ROS production. Addition of 50 μM t-BOOH for 2 h increased ROS and carbonyl groups content and decreased reduced glutathione level. Pre-treatment of cells with CPE significantly prevented the t-BOOH-induced ROS and carbonyl groups and returned antioxidant defences to adequate levels. Thus, Ins-1E cells treated with CPE showed a remarkable recovery of cell viability damaged by t-BOOH, indicating that integrity of surviving machineries in the CPE-treated cells was notably protected against the oxidative insult.

(-)-Epicatechin rich cocoa mediated modulation of oxidative stress regulators in skeletal muscle of heart failure and type 2 diabetes patients

BACKGROUND

Type 2 diabetes (T2D) and heart failure (HF) are associated with high levels of skeletal muscle (SkM) oxidative stress (OS). Health benefits attributed to flavonoids have been ascribed to antioxidation. However, for flavonoids with similar antioxidant potential, end-biological effects vary widely suggesting other mechanistic venues for reducing OS. Decreases in OS may follow the modulation of key regulatory pathways including antioxidant levels (e.g. glutathione) and enzymes such as mitochondrial superoxide dismutase (SOD2) and catalase.

METHODS

We examined OS-related alterations in SkM in T2D/HF patients (as compared vs. healthy controls) and evaluated the effects of three-month treatment with (-)-epicatechin (Epi) rich cocoa (ERC). To evidence Epi as the mediator of the improved OS profile we examined the effects of pure Epi (vs. water) on SkM OS regulatory systems in a mouse model of insulin resistance and contrasted results vs. normal mice.

RESULTS

There were severe alterations in OS regulatory systems in T2D/HF SkM as compared with healthy controls. Treatment with ERC induced recovery in glutathione levels and decreases in the nitrotyrosilation and carbonylation of proteins. With treatment, key transcriptional factors translocate into the nucleus leading to increases in SOD2 and catalase protein expression and activity levels. In insulin resistant mice, there were alterations in muscle OS and pure Epi replicated the beneficial effects of ERC found in humans.

CONCLUSIONS

Major perturbations in SkM OS can be reversed with ERC in T2D/HF patients. Epi likely mediates such effects and may provide an effective means to treat conditions associated with tissue OS.

Cocoa flavonoids improve insulin signalling and modulate glucose production via AKT and AMPK in HepG2 cells

SCOPE

Cocoa and (-)-epicatechin (EC), a main cocoa flavanol, have been suggested to exert beneficial effects in diabetes, but the mechanism for their insulin-like effects remains unknown. In this study, the modulation of insulin signalling by EC and a cocoa phenolic extract (CPE) on hepatic HepG2 cells was investigated by analysing key proteins of the insulin pathways, namely insulin receptor, insulin receptor substrate (IRS) 1 and 2, PI3K/AKT and 5'-AMP-activated protein kinase (AMPK), as well as the levels of the glucose transporter GLUT-2 and the hepatic glucose production.

METHODS AND RESULTS

EC and CPE enhanced the tyrosine phosphorylation and total insulin receptor, IRS-1 and IRS-2 levels and activated the PI3K/AKT pathway and AMPK in HepG2 cells. CPE also enhanced the levels of GLUT-2. Interestingly, EC and CPE modulated the expression of phosphoenolpyruvate carboxykinase, a key protein involved in the gluconeogenesis, leading to a diminished glucose production. In addition, EC- and CPE-regulated hepatic gluconeogenesis was prevented by the blockage of AKT and AMPK.

CONCLUSION

Our data suggest that EC and CPE strengthen the insulin signalling by activating key proteins of that pathway and regulating glucose production through AKT and AMPK modulation in HepG2 cells.

Resveratrol suppresses oxidative stress and inflammatory response in diethylnitrosamine-initiated rat hepatocarcinogenesis

Hepatocellular carcinoma (HCC), one of the most frequent and deadliest cancers, has been increasing considerably in the United States. In the absence of a proven effective therapy for HCC, novel chemopreventive strategies are urgently needed to lower the current morbidity and mortality of HCC. Recently, we have reported that resveratrol, a compound present in grapes and red wine, significantly prevents diethylnitrosamine (DENA)-induced liver tumorigenesis in rats, although the mechanism of action is not completely understood. In the present study, we have examined the underlying mechanisms of resveratrol chemoprevention of hepatocarcinogenesis by investigating the effects of resveratrol on oxidative damage and inflammatory markers during DENA-initiated rat liver carcinogenesis. There was a significant increase in hepatic lipid peroxidation and protein oxidation in carcinogen control animals compared with their normal counterparts at the end of the study (20 weeks). Elevated expressions of inducible nitric oxide synthase and 3-nitrotyrosine were noticed in the livers of the same animals. Dietary resveratrol (50-300 mg/kg) administered throughout the study reversed all the aforementioned markers in a dose-responsive fashion in rats challenged with DENA. Resveratrol also elevated the protein and mRNA expression of hepatic nuclear factor E2-related factor 2 (Nrf2). Results of the present investigation provide evidence that attenuation of oxidative stress and suppression of inflammatory response mediated by Nrf2 could be implicated, at least in part, in the chemopreventive effects of this dietary agent against chemically induced hepatic tumorigenesis in rats. The outcome of this study may benefit the development of resveratrol in the prevention and intervention of human HCC.