Grape seed proanthocyanidin rescues rats from steatosis: a comparative and combination study with metformin

The effects of grape seed extract supplementation on cardiovascular risk factors, liver enzymes and hepatic steatosis in patients with non-alcoholic fatty liver disease: a randomised, double-blind, placebo-controlled study

BACKGROUND

Despite the high antioxidant potential of grape seed extract (GSE), very limited studies have investigated its effect on non-alcoholic fatty liver disease (NAFLD). Therefore, this study was conducted with the aim of investigating the effect of GSE on metabolic factors, blood pressure and steatosis severity in patients with NAFLD.

METHODS

In this double-blind randomized clinical trial study, 50 NAFLD patients were divided into two groups of 25 participants who were treated with 520 mg/day of GSE or the placebo group for 2 months. The parameters of glycemic, lipid profile, blood pressure and steatohepatitis were measured before and after the intervention.

RESULTS

The GSE group had an average age of 43.52 ± 8.12 years with 15 women and 10 men, while the placebo group had an average age of 44.88 ± 10.14 years with 11 women and 14 men. After 2 months of intervention with GSE, it was observed that insulin, HOMA-IR, TC, TG, LDL-c, ALT, AST, AST/ALT, SBP, DBP and MAP decreased and QUICKi and HDL-c increased significantly (p-value for all < 0.05). Also, before and after adjustment based on baseline, the average changes indicated that the levels of insulin, HOMA-IR, TC, TG, LDL-c, SBP, DBP, MAP in the GSE group decreased more than in the control group (p for all < 0.05). Furthermore, the changes in HDL-c were significantly higher in the GSE group (p < 0.05). The between-groups analysis showed a significant decrease in the HOMA-β and AST before and after adjustment based on baseline levels (p < 0.05). Moreover, the changes in QUICKi after adjustment based on baseline levels were higher in the GSE group than in the control group. Also, between-groups analysis showed that the severity of hepatic steatosis was reduced in the intervention group compared to the placebo group (P = 0.002).

CONCLUSIONS

It seems that GSE can be considered one of the appropriate strategies for controlling insulin resistance, hyperlipidemia, hypertension and hepatic steatosis in NAFLD patients.

TRIAL REGISTRATION

The clinical trial was registered in the Iranian Clinical Trial Registration Center (IRCT20190731044392N1). https://irct.behdasht.gov.ir/trial/61413 . (The registration date: 30/03/2022).

The Role of PNPLA3_rs738409 Gene Variant, Lifestyle Factors, and Bioactive Compounds in Nonalcoholic Fatty Liver Disease: A Population-Based and Molecular Approach towards Healthy Nutrition

This study aimed to investigate the impact of a common non-synonymous gene variant (C>G, rs738409) in patatin-like phospholipase domain-containing 3 (PNPLA3), leading to the substitution of isoleucine with methionine at position 148 (PNPLA3-I148M), on susceptibility to nonalcoholic fatty liver disease (NAFLD) and explore potential therapeutic nutritional strategies targeting PNPLA3. It contributed to understanding sustainable dietary practices for managing NAFLD, recently referred to as metabolic-dysfunction-associated fatty liver. NAFLD had been diagnosed by ultrasound in a metropolitan hospital-based cohort comprising 58,701 middle-aged and older Korean individuals, identifying 2089 NAFLD patients. The interaction between PNPLA3 and lifestyle factors was investigated. In silico analyses, including virtual screening, molecular docking, and molecular dynamics simulations, were conducted to identify bioactive compounds from foods targeting PNPLA3(I148M). Subsequent cellular experiments involved treating oleic acid (OA)-exposed HepG2 cells with selected bioactive compounds, both in the absence and presence of compound C (AMPK inhibitor), targeting PNPLA3 expression. Carriers of the risk allele PNPLA3_rs738409G showed an increased association with NAFLD risk, particularly with adherence to a plant-based diet, avoidance of a Western-style diet, and smoking. Delphinidin 3-caffeoyl-glucoside, pyranocyanin A, delta-viniferin, kaempferol-7-glucoside, and petunidin 3-rutinoside emerged as potential binders to the active site residues of PNPLA3, exhibiting a reduction in binding energy. These compounds demonstrated a dose-dependent reduction in intracellular triglyceride and lipid peroxide levels in HepG2 cells, while pretreatment with compound C showed the opposite trend. Kaempferol-7-glucoside and petunidin-3-rutinoside showed potential as inhibitors of PNPLA3 expression by enhancing AMPK activity, ultimately reducing intrahepatic lipogenesis. In conclusion, there is potential for plant-based diets and specific bioactive compounds to promote sustainable dietary practices to mitigate NAFLD risk, especially in individuals with genetic predispositions.

Pharmacology of bioactive compounds from plant extracts for improving non-alcoholic fatty liver disease through endoplasmic reticulum stress modulation: A comprehensive review

Background

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition with significant clinical implications. Emerging research indicates endoplasmic reticulum (ER) stress as a critical pathogenic factor governing inflammatory responses, lipid metabolism and insulin signal transduction in patients with NAFLD. ER stress-associated activation of multiple signal transduction pathways, including the unfolded protein response, disrupts lipid homeostasis and substantially contributes to NAFLD development and progression. Targeting ER stress for liver function enhancement presents an innovative therapeutic strategy. Notably, the natural bioactive compounds of plant extracts have shown potential for treating NAFLD by reducing the level of ER stress marker proteins and mitigating inflammation, stress responses, and de novo lipogenesis. However, owing to limited comprehensive reviews, the effectiveness and pharmacology of these bioactive compounds remain uncertain.

Objectives

To address the abovementioned challenges, the current review categorizes the bioactive compounds of plant extracts by chemical structures and properties into flavonoids, phenols, terpenoids, glycosides, lipids and quinones and examines their ameliorative potential for NAFLD under ER stress.

Methods

This review systematically analyses the literature on the interactions of bioactive compounds from plant extracts with molecular targets under ER stress, providing a holistic view of NAFLD therapy.

Results

Bioactive compounds from plant extracts may improve NAFLD by alleviating ER stress; reducing lipid synthesis, inflammation, oxidative stress and apoptosis and enhancing fatty acid metabolism. This provides a multifaceted approach for treating NAFLD.

Conclusion

This review underscores the role of ER stress in NAFLD and the potential of plant bioactive compounds in treating this condition. The molecular mechanisms by which plant bioactive compounds interact with their ER stress targets provide a basis for further exploration in NAFLD management.

Proanthocyanidins-Based Synbiotics as a Novel Strategy for Nonalcoholic Fatty Liver Disease (NAFLD) Risk Reduction

Nonalcoholic fatty liver disease (NAFLD), the most common liver disease worldwide, is a spectrum of liver abnormalities ranging from steatosis to nonalcoholic steatohepatitis (NASH) characterized by excessive lipid accumulation. The prevalence of NAFLD is predicted to increase rapidly, demanding novel approaches to reduce the global NAFLD burden. Flavonoids, the most abundant dietary polyphenols, can reduce the risk of NAFLD. The majority of dietary flavonoids are proanthocyanidins (PACs), which are oligomers and polymers of the flavonoid sub-group flavan-3-ols. The efficacy of PAC in reducing the NAFLD risk can be significantly hindered by low bioavailability. The development of synbiotics by combining PAC with probiotics may increase effectiveness against NAFLD by biotransforming PAC into bioavailable metabolites. PAC and probiotic bacteria are capable of mitigating steatosis primarily through suppressing de novo lipogenesis and promoting fatty acid β-oxidation. PAC and probiotic bacteria can reduce the progression of steatosis to NASH mainly through ameliorating hepatic damage and inflammation induced by hepatic oxidative stress, endoplasmic reticulum stress, and gut microbiota dysbiosis. Synbiotics of PAC are superior in reducing the risk of NAFLD compared to independent administration of PAC and probiotics. The development of PAC-based synbiotics can be a novel strategy to mitigate the increasing incidence of NAFLD.

The Chemical Profile, Antioxidant, and Anti-Lipid Droplet Activity of Fluid Extracts from Romanian Cultivars of Haskap Berries, Bitter Cherries, and Red Grape Pomace for the Management of Liver Steatosis

This study aimed to investigate, for the first time, the chemical composition and antioxidant activity of fluid extracts obtained from three Romanian cultivars of haskap berries (Lonicera caerulea L.) var. Loni, bitter cherries (Prunus avium var. sylvestris Ser.) var. Silva, and pomace from red grapes (Vitis vinifera L.) var. Mamaia, and their capacity to modulate in vitro steatosis, in view of developing novel anti-obesity products. Total phenolic, flavonoid, anthocyanin, and ascorbic acid content of fluid extracts was spectrophotometrically assessed and their free radical scavenging capacity was evaluated using Trolox Equivalent Antioxidant Capacity (TEAC) and free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition assays. The Pearson coefficients showed a moderate correlation between the antioxidant activity of fluid extracts and their phenolic content, but a strong correlation between anthocyanin and ascorbic acid content. HPLC analysis identified and quantified the main phenolic compounds of chlorogenic and syringic acid, catechin, and glycosylated kaempferol, apigenin, and quercetin, in variable proportions. An in vitro experimental model of steatosis was developed in HepG2 hepatocytes treated with a mixture of free fatty acids. Cell culture analyses showed that cytocompatible concentrations of fluid extracts could significantly reduce the lipid accumulation and inhibit the reactive oxygen species, malondialdehyde, and nitric oxide secretion in stressed hepatocytes. In conclusion, these results put an emphasis on the chemical compounds' high antioxidant and liver protection capacity of unstudied fluid extracts obtained from Romanian cultivars of bitter cherries var. Silva and pomace of red grapes var. Mamaia, similar to the fluid extract of haskap berries var. Loni, in particular, the positive modulation of fat deposition next to oxidative stress and the lipid peroxidation process triggered by fatty acids in HepG2 hepatocytes. Consequently, this study indicated that these fluid extracts could be further exploited as hepatoprotective agents in liver steatosis, which provides a basis for the further development of novel extract mixtures with synergistic activity as anti-obesity products.

Chemical Composition and Insulin-Resistance Activity of Arginine-Loaded American Cranberry (Vaccinium macrocarpon Aiton, Ericaceae) Leaf Extracts

One of the key pathogenetic links in type 2 diabetes mellitus (T2DM) is the formation of insulin resistance (IR). Besides a wide selection of synthetic antidiabetic drugs, various plant-origin extracts are also available to support the treatment of T2DM. This study aimed to investigate and gain knowledge of the chemical composition and potential IR correction effect of American cranberry (Vaccinium macrocarpon Aiton) leaf extracts and formulate novel 3D-printed oral dosage forms for such extracts. The bioactivity and IR of L-arginine-loaded cranberry leaf extracts were studied in vivo in rats. The cranberry leaf extracts consisted of quinic, 3-caffeoylquinic (chlorogenic), p-coumaroylquinic acids, quercetin 3-O-galactoside, quercetin-3-O-glucoside, quercetin-3-xyloside, quercetin-3-O-arabino pyranoside, quercetin-3-O-arabinofuranoside, quercetin 3-O-rhamnoside, and quercetin-O-p-coumaroyl hexoside-2 identified by HPLC. In vivo studies with rats showed that the oral administration of the cranberry leaf extracts had a positive effect on insulin sensitivity coefficients under the insulin tolerance test and affected homeostasis model assessment IR levels and liver lipid content with experimental IR. A novel 3D-printed immediate-release dosage form was developed for the oral administration of cranberry leaf extracts using polyethylene oxide as a carrier gel in semi-solid extrusion 3D printing. In conclusion, American cranberry leaf extracts loaded with L-arginine could find uses in preventing health issues associated with IR.

Targeting Metabolic Syndrome in Hidradenitis Suppurativa by Phytochemicals as a Potential Complementary Therapeutic Strategy

Hidradenitis suppurativa (HS) is a chronic inflammatory disease characterized by the appearance of painful inflamed nodules, abscesses, and pus-draining sinus tracts in the intertriginous skin of the groins, buttocks, and perianal and axillary regions. Despite its high prevalence of ~0.4-1%, therapeutic options for HS are still limited. Over the past 10 years, it has become clear that HS is a systemic disease, associated with various comorbidities, including metabolic syndrome (MetS) and its sequelae. Accordingly, the life expectancy of HS patients is significantly reduced. MetS, in particular, obesity, can support sustained inflammation and thereby exacerbate skin manifestations and the chronification of HS. However, MetS actually lacks necessary attention in HS therapy, underlining the high medical need for novel therapeutic options. This review directs attention towards the relevance of MetS in HS and evaluates the potential of phytomedical drug candidates to alleviate its components. It starts by describing key facts about HS, the specifics of metabolic alterations in HS patients, and mechanisms by which obesity may exacerbate HS skin alterations. Then, the results from the preclinical studies with phytochemicals on MetS parameters are evaluated and the outcomes of respective randomized controlled clinical trials in healthy people and patients without HS are presented.

Hepatotoxicity of polymeric proanthocyanidins is caused by translocation of bacterial lipopolysaccharides through impaired gut epithelium

Polymeric proanthocyanidins (P-PAC) induced hepatotoxicity in C57BL/6 mice. Mice were supplemented with P-PAC alone or with a mixture of probiotic bacteria (PB), Lactobacillus, Bifidobacterium, and Akkermansia muciniphila for 14 consecutive days. The liver tissues of sacrificed mice were analyzed by mass spectrometry to identify and quantify the P-PAC metabolites. Potential P-PAC metabolites, 2-hydroxyphenylacetic acid and pyrocatechol were detected in higher concentrations and 4-hydroxybenzoic acid was detected exclusively in the mice supplemented with P-PAC and PB. Supplementation with P-PAC alone or with PB caused no shift in the α-diversity of mice gut microbiota. P-PAC induced nonalcoholic steatohepatitis in mice through increasing liver exposure to intestinal bacterial lipopolysaccharides by reducing expression of gut epithelial tight junction proteins, claudin-3 and occludin. Lipopolysaccharide concentrations in the livers of mice supplemented with P-PAC were significantly high compared to the control mice. Furthermore, P-PAC downregulated the expressions of claudin-3 and claudin-4 tight junction proteins in cultured Caco-2 cell monolayers. PB biotransformed P-PAC into bioavailable metabolites and potentially reduced the toxicity of P-PAC. The toxicity of P-PAC and their synbiotics need to be critically evaluated for the safety of human consumption.

The effect of grape products on liver enzymes: A systematic review and meta-analysis of randomized controlled trials

The favorable influence of grape consumption on metabolic diseases has previously been shown in studies. We sought to assess the effects of grape intake on liver enzymes, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), in adults. We performed literature search in online databases, to find eligible randomized controlled trials (RCTs). we considered RCTs that met the following criteria: RCTs consisted of use of grape products on ALT, AST, and ALP in adults (≥18 years) with at least 2 weeks intervention duration. Pooling data from 11 trials showed that grape products intake significantly reduced ALP (p = .010), without any significant changes in ALT (p = .234) and AST (p = .300). In subgroup analysis, we found a significant reduction in ALP, ALT, and AST when the duration of intervention was ≥12 weeks, and when grape seed extract (GSE) was administered. The variable duration and dosage of intervention was one of the sources of bias in our meta-analysis. Additionally, participants involved in included studies had different physiological status and various age groups. Grape products administration may significantly improve ALT, AST, and ALP in adults in long-term interventions and/or when GSE is administered. It should be noted that the favorable effects of grape consumption were small and may not reach clinical importance.

Optimization of the Extraction of Proanthocyanidins from Grape Seeds Using Ultrasonication-Assisted Aqueous Ethanol and Evaluation of Anti-Steatosis Activity In Vitro

Conventional extraction methods of proanthocyanidins (PAC) are based on toxic organic solvents, which can raise concerns about the use of extracts in supplemented food and nutraceuticals. Thus, a PAC extraction method was developed for grape seeds (GS) and grape seed powder using food-grade ethanol by optimizing the extraction conditions to generate the maximum yield of PAC. Extraction parameters, % ethanol, solvent: solid (s:s) ratio, sonication time, and temperature were optimized by the central composite design of the response surface method. The yields of PAC under different extraction conditions were quantified by the methylcellulose precipitable tannin assay. The final optimum conditions were 47% ethanol, 10:1 s:s ratio (v:w), 53 min sonication time, and 60 °C extraction temperature. High-performance liquid chromatography analysis revealed the presence of catechin, procyanidin B2, oligomeric and polymeric PAC in the grape seed-proanthocyanidin extracts (GS-PAC). GS-PAC significantly reduced reactive oxygen species and lipid accumulation in the palmitic-acid-induced mouse hepatocytes (AML12) model of steatosis. About 50% of the PAC of the GS was found to be retained in the by-product of wine fermentation. Therefore, the developed ethanol-based extraction method is suitable to produce PAC-rich functional ingredients from grape by-products to be used in supplemented food and nutraceuticals.

Mitochondrial Targeting Therapeutics: Promising Role of Natural Products in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common chronic liver diseases worldwide, and its prevalence is still growing rapidly. However, the efficient therapies for this liver disease are still limited. Mitochondrial dysfunction has been proven to be closely associated with NAFLD. The mitochondrial injury caused reactive oxygen species (ROS) production, and oxidative stress can aggravate the hepatic lipid accumulation, inflammation, and fibrosis. which contribute to the pathogenesis and progression of NAFLD. Therefore, pharmacological therapies that target mitochondria could be a promising way for the NAFLD intervention. Recently, natural products targeting mitochondria have been extensively studied and have shown promising pharmacological activity. In this review, the recent research progress on therapeutic effects of natural-product-derived compounds that target mitochondria and combat NAFLD was summarized, aiming to provide new potential therapeutic lead compounds and reference for the innovative drug development and clinical treatment of NAFLD.

Molecular Determinants of the Cardiometabolic Improvements of Dietary Flavanols Identified by an Integrative Analysis of Nutrigenomic Data from a Systematic Review of Animal Studies

SCOPE

Flavanols are important polyphenols of the human diet with extensive demonstrations of their beneficial effects on cardiometabolic health. They contribute to preserve health acting on a large range of cellular processes. The underlying mechanisms of action of flavanols are not fully understood but involve a nutrigenomic regulation.

METHODS AND RESULTS

To further capture how the intake of dietary flavanols results in the modulation of gene expression, nutrigenomics data in response to dietary flavanols obtained from animal models of cardiometabolic diseases have been collected and submitted to a bioinformatics analysis. This systematic analysis shows that dietary flavanols modulate a large range of genes mainly involved in endocrine function, fatty acid metabolism, and inflammation. Several regulators of the gene expression have been predicted and include transcription factors, miRNAs and epigenetic factors.

CONCLUSION

This review highlights the complex and multilevel action of dietary flavanols contributing to their strong potential to preserve cardiometabolic health. The identification of the potential molecular mediators and of the flavanol metabolites driving the nutrigenomic response in the target organs is still a pending question which the answer will contribute to optimize the beneficial health effects of dietary bioactives.

Grape seed proanthocyanidins and metformin combination attenuate hepatic endoplasmic reticulum stress in rats subjected to nutrition excess

CONTEXT

Endoplasmic reticulum (ER) stress in the liver is a pathological outcome of nutrient excess and is suggested to be one of the hits for progressive liver injury.

OBJECTIVE

This study investigated whether grape seed proanthocyanidins (GSP) and metformin (MET) alone or in combination can relieve hepatic ER stress induced in rats subjected to calorie excess.

MATERIAL AND METHODS

Male albino Wistar rats were given high calorie diet (HCD) for 45 days, while GSP (100 mg/kg body weight) and MET (50 mg/kg body weight) were administered either alone or in combination for last 15 days.

RESULTS

GSP, MET or both had reduced the levels of ER stress markers and chaperons, and suppressed the activation of lipogenic and inflammatory mediators in rat liver.

DISCUSSION

Though GSP and MET had reduced ER stress and inflammation individually, combination treatment with GSP + MET was more effective.

CONCLUSION

We suggest intervention with GSP and MET intake has to be considered for the management of liver disorders.

Hepatoprotective Effect of Fresh Grape Juice Prepared by a Low-Speed Masticating Juicer in db/db Mice

This study investigated the hepatoprotective effect of fresh grape juice prepared using a low-speed masticating (LSM) juicer or a high-speed centrifugal (HSC) juicer in mice. Six-week-old db/db mice were fed on an AIN-93G diet or a diet containing 1% freeze-dried LSM or HSC grape juice for 7 weeks. Treatment with LSM grape juice significantly decreased hepatic triglycerides, serum aspartate transaminase activities, and homeostasis model assessment for insulin resistance values, whereas HSC juice did not significantly influence these parameters. The LSM grape juice showed higher antioxidant and anti-inflammatory activities than HSC juice. The benefits of LSM grape juice are probably due to a much higher proanthocyanidin content than that of HSC juice. These results suggest that LSM grape juice can exert hepatoprotective effects in db/db mice, partly through improving insulin resistance and promoting antioxidant and inflammatory activities.

Effects of DA-5513 on alcohol metabolism and alcoholic fatty liver in rats

Hangover is characterized by a number of unpleasant physical and mental symptoms that occur after heavy alcohol drinking. In addition, consistently excessive alcohol intake is considered as a major reason causes liver disease. The present study investigated the in vivo effects of DA-5513 (Morning care® Kang Hwang) on biological parameters relevant to hangover relief and alcoholic fatty liver. Blood alcohol and acetaldehyde concentrations were determined in rats administered a single dose of alcohol and treated with DA-5513 or commercially available hangover relief beverages (Yeomyung® and Ukon®). The effects of DA-5513 on alcoholic fatty liver were also determined in rats fed alcohol-containing Lieber-DeCarli diets for 4 weeks. Serum liver function markers (aspartate and alanine aminotransferase activities) and serum/liver lipid levels were assessed. Blood alcohol and acetaldehyde concentrations were lower in the groups treated with DA-5513 or Yeomyung®, as compared with control rats. However, Ukon® did not produce any significant effects on these parameters. Treatment with DA-5513 significantly reduced serum aspartate and alanine aminotransferase activities and markedly reduced serum cholesterol and triglyceride levels, as compared with control rats. Histological observations using Oil Red O staining found that DA-5513 delayed the development of alcoholic fatty liver by reversing hepatic fat accumulation. These findings suggest that DA-5513 could have a beneficial effect on alcohol-induced hangovers and has the potential to ameliorate alcoholic fatty liver.

Oxidative Stress as a Critical Factor in Nonalcoholic Fatty Liver Disease Pathogenesis

SIGNIFICANCE

Nonalcoholic fatty liver disease (NAFLD), characterized by liver triacylglycerol build-up, has been growing in the global world in concert with the raised prevalence of cardiometabolic disorders, including obesity, diabetes, and hyperlipemia. Redox imbalance has been suggested to be highly relevant to NAFLD pathogenesis. Recent Advances: As a major health problem, NAFLD progresses to the more severe nonalcoholic steatohepatitis (NASH) condition and predisposes susceptible individuals to liver and cardiovascular disease. Although NAFLD represents the predominant cause of chronic liver disorders, the mechanisms of its development and progression remain incompletely understood, even if various scientific groups ascribed them to the occurrence of insulin resistance, dyslipidemia, inflammation, and apoptosis. Nevertheless, oxidative stress (OxS) more and more appears as the most important pathological event during NAFLD development and the hallmark between simple steatosis and NASH manifestation.

CRITICAL ISSUES

The purpose of this article is to summarize recent developments in the understanding of NAFLD, essentially focusing on OxS as a major pathogenetic mechanism. Various attempts to translate reactive oxygen species (ROS) scavenging by antioxidants into experimental and clinical studies have yielded mostly encouraging results.

FUTURE DIRECTIONS

Although augmented concentrations of ROS and faulty antioxidant defense have been associated to NAFLD and related complications, mechanisms of action and proofs of principle should be highlighted to support the causative role of OxS and to translate its concept into the clinic. Antioxid. Redox Signal. 26, 519-541.

Effects of Natural Products on Fructose-Induced Nonalcoholic Fatty Liver Disease (NAFLD)

As a sugar additive, fructose is widely used in processed foods and beverages. Excessive fructose consumption can cause hepatic steatosis and dyslipidemia, leading to the development of metabolic syndrome. Recent research revealed that fructose-induced nonalcoholic fatty liver disease (NAFLD) is related to several pathological processes, including: (1) augmenting lipogenesis; (2) leading to mitochondrial dysfunction; (3) stimulating the activation of inflammatory pathways; and (4) causing insulin resistance. Cellular signaling research indicated that partial factors play significant roles in fructose-induced NAFLD, involving liver X receptor (LXR)α, sterol regulatory element binding protein (SREBP)-1/1c, acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD), peroxisome proliferator–activated receptor α (PPARα), leptin nuclear factor-erythroid 2-related factor 2 (Nrf2), nuclear factor kappa B (NF-κB), tumor necrosis factor α (TNF-α), c-Jun amino terminal kinase (JNK), phosphatidylinositol 3-kinase (PI3K) and adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK). Until now, a series of natural products have been reported as regulators of NAFLD in vivo and in vitro. This paper reviews the natural products (e.g., curcumin, resveratrol, and (−)-epicatechin) and their mechanisms of ameliorating fructose-induced NAFLD over the past years. Although, as lead compounds, natural products usually have fewer activities compared with synthesized compounds, it will shed light on studies aiming to discover new drugs for NAFLD.

Chardonnay Grape Seed Flour Ameliorates Hepatic Steatosis and Insulin Resistance via Altered Hepatic Gene Expression for Oxidative Stress, Inflammation, and Lipid and Ceramide Synthesis in Diet-Induced Obese Mice

To identify differentially expressed hepatic genes contributing to the improvement of high-fat (HF) diet-induced hepatic steatosis and insulin resistance following supplementation of partially defatted flavonoid-rich Chardonnay grape seed flour (ChrSd), diet-induced obese (DIO) mice were fed HF diets containing either ChrSd or microcrystalline cellulose (MCC, control) for 5 weeks. The 2-h insulin area under the curve was significantly lowered by ChrSd, indicating that ChrSd improved insulin sensitivity. ChrSd intake also significantly reduced body weight gain, liver and adipose tissue weight, hepatic lipid content, and plasma low-density lipoprotein (LDL)-cholesterol, despite a significant increase in food intake. Exon microarray analysis of hepatic gene expression revealed down-regulation of genes related to triglyceride and ceramide synthesis, immune response, oxidative stress, and inflammation and upregulation of genes related to fatty acid oxidation, cholesterol, and bile acid synthesis. In conclusion, the effects of ChrSd supplementation in a HF diet on weight gain, insulin resistance, and progression of hepatic steatosis in DIO mice were associated with modulation of hepatic genes related to oxidative stress, inflammation, ceramide synthesis, and lipid and cholesterol metabolism.

Dietary proanthocyanidins boost hepatic NAD(+) metabolism and SIRT1 expression and activity in a dose-dependent manner in healthy rats

Proanthocyanidins (PACs) have been reported to modulate multiple targets by simultaneously controlling many pivotal metabolic pathways in the liver. However, the precise mechanism of PAC action on the regulation of the genes that control hepatic metabolism remains to be clarified. Accordingly, we used a metabolomic approach combining both nuclear magnetic resonance and mass spectrometry analysis to evaluate the changes induced by different doses of grape-seed PACs in the liver of healthy rats. Here, we report that PACs significantly increased the hepatic nicotinamide adenine dinucleotide (NAD(+)) content in a dose-dependent manner by specifically modulating the hepatic concentrations of the major NAD(+) precursors as well as the mRNA levels of the genes that encode the enzymes involved in the cellular metabolism of NAD(+). Notably, Sirtuin 1 (Sirt1) gene expression was also significantly up-regulated in a dose-response pattern. The increase in both the NAD(+) availability and Sirt1 mRNA levels, in turn, resulted in the hepatic activation of SIRT1, which was significantly associated with improved protection against hepatic triglyceride accumulation. Our data clearly indicates that PAC consumption could be a valid tool to enhance hepatic SIRT1 activity through the modulation of NAD(+) levels.

Alcohol-free fermented blueberry-blackberry beverage phenolic extract attenuates diet-induced obesity and blood glucose in C57BL/6J mice

The aim of this study was to determine the potential of phenolic compounds from a fermented blackberry-blueberry beverage to reduce diet-induced obesity and hyperglycemia in mice fed a 60% high-fat diet (HFD) for 10weeks after 1week of pretreatment. C57BL/6J mice were randomized into six groups and allowed to drink (ad libitum) an alcohol-free blackberry-blueberry beverage [alcohol-free fermented beverage (AFFB), 8.4mg anthocyanin (ANC)/kg body weight (BW)/day]; three doses of a phenolic extract [postamberlite extract (PAE)] from AFFB at 0.1×, 1× and 2× ANC concentrations; sitagliptin (hypoglycemic positive control); or water (negative control). Weight and fat mass gain were attenuated in mice receiving the highest doses of PAE (18.9mg ANC/kg BW/day, P<.05). There were also reductions (P<.05) in percent fat mass, epididymal fat pad weights, mean adipocyte diameters and plasma triglycerides and cholesterol associated with PAE treatments. By the end of the study, fasting blood glucose for mice receiving 9mg (1×) or 18.9mg (2×) ANC/kg BW/day was significantly lower than in the water and the sitagliptin groups (P<.05). Histological and histochemical analyses revealed an unexpected change in liver of mice fed ANC at 1× or 2× doses consisting of liver enlargement and increased lipid deposition. PAE also induced the most differential gene expression changes, including highly significant downstream effects at all doses to reduce d-glucose concentrations. Overall, phenolic compounds from the fermented blueberry-blackberry beverage had an impact to attenuate the development of obesity and fasting blood glucose in C57BL/6J mice.

Grape pomace and grape pomace extract improve insulin signaling in high-fat-fructose fed rat-induced metabolic syndrome

In this study the effect of diet supplementation with grape pomace (GP) and grape pomace extract (GPE) on insulin sensitive tissues (adipose, liver and muscle) was evaluated in an experimental model of metabolic syndrome (MetS).

Relevant Aspects of Nutritional and Dietary Interventions in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the main cause of liver disease worldwide. NAFLD is linked to circumstances such as type 2 diabetes, insulin resistance, obesity, hyperlipidemia, and hypertension. Since the obesity figures and related comorbidities are increasing, NAFLD has turned into a liver problem that has become progressively more common. Currently, there is no effective drug therapy for NAFLD; therefore, interventions in lifestyles remain the first line of treatment. Bearing in mind that adherence rates to this type of treatment are poor, great efforts are currently focused on finding novel therapeutic agents for the prevention in the development of hepatic steatosis and its progression to nonalcoholic steatohepatitis and cirrhosis. This review presents a compilation of the scientific evidence found in the last years showing the results of interventions in lifestyle, diet, and behavioral therapies and research results in human, animal and cell models. Possible therapeutic agents ranging from supplementation with vitamins, amino acids, prebiotics, probiotics, symbiotics, polyunsaturated fatty acids and polyphenols to interventions with medicinal plants are analyzed.

Quantitative proteomics study of protective effects of grape seed procyanidin B2 on diabetic cardiomyopathy in db/db mice

Diabetic cardiomyopathy is one of the major complications of diabetes mellitus. Oxidative stress appears to play a substantial role in cardiomyopathy. Grape seed procyanidin B2 (GSPB2) has been known as an anti-oxidant in treating diabetes mellitus; however, little is known about its effects and underlying mechanisms on diabetic cardiomyopathy. The present study is to explore the molecular targets of GSPB2 responsible for the anti-oxidative effects in db/db mice by quantitative proteomics. GSPB2 (30 mg/kg body weight/day) were intragastric administrated to db/db mice for 10 weeks. Proteomics of the heart tissue extracts by isobaric tags for relative and absolute quantification analysis was obtained from db/db mice. Our study provides important evidence that GSPB2 protect against cardiomyopathy in diabetes mellitus, which are believed to result from regulating the expression of key proteins involving cardiac fibrosis and proliferation. GSPB2 could be expected to become novel clinical application in fighting against diabetic cardiomyopathy.