Chronic dietary intake of quercetin alleviates hepatic fat accumulation associated with consumption of a Western-style diet in C57/BL6J mice

Quercetin intervention reduced hepatic fat deposition in patients with nonalcoholic fatty liver disease: a randomized, double-blind, placebo-controlled crossover clinical trial

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has become a growing public health problem worldwide. However, there is still lack of effective treatment strategies except lifestyle intervention.

OBJECTIVES

To evaluate whether quercetin improves intrahepatic lipid content in patients with NAFLD.

METHODS

In this randomized, double-blind, placebo-controlled crossover trial, 41 patients with NAFLD were randomly assigned to receive the quercetin (500 mg) or placebo capsules for 12 wk, then switched interventions for another 12 wk after a 4-wk washout period. The primary outcome was intrahepatic lipid content evaluated by magnetic resonance imaging estimated proton density fat fraction. The secondary outcomes were liver function measurements, etc. Safety outcomes included blood routine.

RESULTS

A total of 36 patients completed the trial. In intention-to-treat analyses, the quercetin intervention moderately decreased the intrahepatic lipid contents from 11.5% ± 6.4% to 9.6% ± 5.8%, compared with the placebo intervention (decreased by 0.1% ± 2.6%, P = 0.013 and adjusted P value is 0.028). Body weight and body mass index were mildly reduced by 1.5 ± 2.6 kg and 0.5 ± 0.9 kg/m2 after the quercetin intervention (P < 0.05 and both adjusted P values are 0.038), whereas the reductions were only 0.2 ± 1.8 kg and 0.1 ± 0.7 kg/m2 after the placebo intervention. The intrahepatic lipid content reductions were noticeably positively associated with the body weight losses after the quercetin and placebo interventions (r = 0.557 and 0.412, P < 0.001 and P = 0.007, respectively). Subgroup analyses found that the reduction of intrahepatic lipid contents in females (3.0% ± 3.7%) was about twice as large as that in males (1.4% ± 2.5%) with a trend of statistical significance (P = 0.113 and adjusted P value is 0.061). There were no significant differences in other secondary and safety outcomes. No adverse events associated with study intervention were found.

CONCLUSIONS

Twelve weeks treatment of quercetin could reduce intrahepatic lipid contents in patients with NAFLD, possibly explained by a slightly larger body weight loss in the quercetin group.

TRIAL REGISTRATION

The trial is registered at www.chictr.org.cn as ChiCTR2100047904.

The comparison of the antidiabetic effects of exenatide, empagliflozin, quercetin, and combination of the drugs in type 2 diabetic rats

BACKGROUND

Type 2 diabetes, a metabolic disease that involves extended treatment, is rapidly increasing in humans and animals worldwide.

OBJECTIVES

This study aimed to compare monotherapy and combined therapy of exenatide, empagliflozin, and quercetin in 67 Wistar Albino male rats.

METHODS

The animals were divided into the following seven groups: healthy control, diabetes control, diabetes + sham, diabetes + exenatide (10 μg/kg), diabetes + empagliflozin (50 mg/kg), diabetes + quercetin (50 mg/kg), and diabetes + combination treatment. The treatments were continued for 8 weeks.

RESULTS

At the end of the experiment, glucose and HbA1c levels decreased with all monotherapy treatments and the combination treatments, while insulin levels increased with exenatide and combined treatments. Adiponectin levels increased with empagliflozin, quercetin, and combined treatments, while leptin levels decreased only with combined treatments. All monotherapies caused an increase in total antioxidant levels. Exenatide and quercetin treatments reduced low-density lipoprotein (LDL) levels; therewithal, exenatide and combined treatments increased high-density lipoprotein (HDL) levels. Triglyceride levels decreased in all treatment groups. The homeostatic model assessment for insulin resistance (HOMA-IR) level decreased with the combined treatment; on the contrary, the homeostatic model assessment for β-cell activity (HOMA-β) level increased with empagliflozin, exenatide, and combined treatments.

CONCLUSION

In conclusion, the antidiabetic effects of exenatide were more pronounced than empagliflozin and quercetin, however, the combined treatment had better antidiabetic and antihyperlipidemic effects than monotherapies. Quercetin could be a supportive or food supplement antidiabetic agent. The exenatide treatment can be recommended for monotherapy in type 2 patients, and the combination of empagliflozin, exenatide, and quercetin may be effective in diabetic patients who need combined therapy.

Integrated transcriptomic landscape of the effect of anti-steatotic treatments in high-fat diet mouse models of non-alcoholic fatty liver disease

High-fat diet (HFD) mouse models are widely used in research to develop medications to treat non-alcoholic fatty liver disease (NAFLD), as they mimic the steatosis, inflammation, and hepatic fibrosis typically found in this complex human disease. The aims of this study were to identify a complete transcriptomic signature of these mouse models and to characterize the transcriptional impact exerted by different experimental anti-steatotic treatments. For this reason, we conducted a systematic review and meta-analysis of liver transcriptomic studies performed in HFD-fed C57BL/6J mice, comparing them with control mice and HFD-fed mice receiving potential anti-steatotic treatments. Analyzing 21 studies broaching 24 different treatments, we obtained a robust HFD transcriptomic signature that included 2,670 differentially expressed genes and 2,567 modified gene ontology biological processes. Treated HFD mice generally showed a reversion of this HFD signature, although the extent varied depending on the treatment. The biological processes most frequently reversed were those related to lipid metabolism, response to stress, and immune system, whereas processes related to nitrogen compound metabolism were generally not reversed. When comparing this HFD signature with a signature of human NAFLD progression, we identified 62 genes that were common to both; 10 belonged to the group that were reversed by treatments. Altered expression of most of these 10 genes was confirmed in vitro in hepatocytes and hepatic stellate cells exposed to a lipotoxic or a profibrogenic stimulus, respectively. In conclusion, this study provides a vast amount of information about transcriptomic changes induced during the progression and regression of NAFLD and identifies some relevant targets. Our results may help in the assessment of treatment efficacy, the discovery of unmet therapeutic targets, and the search for novel biomarkers. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Single oral administration of quercetin glycosides prevented acute hyperglycemia by promoting GLUT4 translocation in skeletal muscles through the activation of AMPK in mice

Quercetin is a natural flavonol and has various health beneficial functions. Our pervious study demonstrated that long-term feeding (13 weeks) of quercetin and its glycosides, isoquercitrin, rutin, and enzymatically modified isoquercitrin, which is a mixture of quercetin monoglycoside and its oligoglycosides, prevented hyperglycemia and adiposity in mice fed a high-fat diet but not standard diet. It is, however, unclear whether a single administration of these compounds prevent postprandial hyperglycemia or not. In the present study, we estimated their prevention effect on acute hyperglycemia by an oral glucose tolerance test in ICR mice and investigated its mechanism. It was found that quercetin glycosides, but not the aglycone, suppressed acute hyperglycemia and isoquercitrin showed the strongest effect among the glycosides. As the underlying mechanism, quercetin glycosides promoted translocation of glucose transporter 4 to the plasma membrane of skeletal muscle of mice through phosphorylation of adenosine monophosphate-activated protein kinase and its upstream Ca2+/calmodulin-dependent protein kinase kinase β without activating the insulin- and JAK/STAT-signal pathways. In conclusion, single oral administration of quercetin glycosides prevented a blood sugar spike by promoting glucose transporter 4 translocation through activating the CAMKKβ/AMPK signaling pathway.

Upregulation of PCSK9, rho kinase and cardiac troponin by Eucalyptus globulus leaf extract improves fructose-streptozotocin-induced diabetic cardiac dysfunction in rats

CONTEXT

The effect of Eucalyptus globulus in diabetic cardiac dysfunction and the possible mechanisms involved have not been explored.

OBJECTIVE

To evaluate the effect of ethanol leaf extract of E. globulus (NEE) on the cardiac function of fructose/streptozotocin-induced diabetic rats.

MATERIALS AND METHODS

Type-2 diabetes was induced in rats with 10% fructose feeding for 14 days and an intraperitoneal administration of 40 mg/kg streptozotocin. Diabetic animals were treated with NEE (100-400 mg/kg) or 5 mg/kg glibenclamide orally for 21 days. Biochemical assays, histopathological examination and analyses of PCSK9, Rho kinase and Cardiac troponin expression were performed.

RESULTS

The untreated diabetic group showed decreased expression of the genes, oxidative stress, dyslipidemia, increased activities of creatine kinase MB and lactate dehydrogenase, reduced nitric oxide level, and depletion of cardiomyocytes, which were reversed in NEE treated groups.

CONCLUSIONS

Eucalyptus globulus ameliorated diabetic cardiac dysfunction through increased PCSK9, Rho kinase and Cardiac troponin expression.

Two-month period of 500 mg lecithin-based delivery form of quercetin daily dietary supplementation counterbalances chronic fatigue symptoms: A double-blind placebo controlled clinical trial

BACKGROUND

Chronic fatigue (CF) is a complex phenomenon without clear etiology that may require long-term treatment, but to date, no specific therapy has been identified for it. Some botanicals might be helpful in the management of CF. Among these botanicals, quercetin demonstrates its capacity to modulate multiple biological pathways and acknowledged major properties in CF: antioxidant, anti-inflammatory, immunomodulating, improving exercise endurance, enhancing mitochondrial biogenesis, repairing mitochondrial dysfunction.

PURPOSE

Given this background, the aim of this study was to evaluate if a 2-month period of daily Quercetin Phytosome™ 500 mg supplementation is of benefit for the relief of CF.

METHODS

The primary end point has been the evaluation of fatigue, by Fatigue Impact Scale (FIS-40). The secondary end points have been the assessment of sleep, by Pittsburgh Sleep Quality Index (PSQI), evaluation of muscle performance, by short physical performance battery and by wearable armband-shaped sensor in order to evaluate the number of steps, body composition, by DXA and quality of life by Short-Form 12-Item Health Survey (SF-12).

RESULTS

Seventy-eight subjects (42 F; 36 M) (mean age 56 ± 9) reporting CF symptoms, completed the study (placebo/supplement 38/40). The FIS-40 mean difference changes between groups (supplement minus placebo) was - 10.583 points (CI95% -11.985; -9.182) (p < 0.001). Also, statistically significant changes between groups have been recorded in Pittsburgh Sleep Quality Index - 2.040 points (CI95%: -2.770; -1.309), p < 0.01), number of steps 1443.152 (CI95%: 1199.556; 1686.749), and SPPB (score) 0.248 (CI95%: 0.105; 0.391) (p < 0.001).

CONCLUSION

The quercetin supplementation counterbalances CF symptoms.

Cardioprotective effect of the quercetin on cardiovascular remodeling and atherosclerosis in rodents fed a high-fat diet: A systematic review

Cardiovascular diseases (CVD) are the leading cause of death globally, estimated at 17.9 million premature deaths. Several risk factors contribute to the development of CVD, including unhealthy diet rich in saturated fat. Quercetin (Q) is a important natural flavonoid with cardioprotective effect. However, it is crucial to understand and clarify which dosages and intervention times quercetin promotes better cardioprotective effects when exposed to a High-Fat Diet (HFD). We aim was to carry out a review to identify and compare experimental studies that investigated the quercetin effect on cardiac parameters in rodents fed a HFD. This literature search was performed through the specialized databases PubMed, Embase, Web of Science and Lilacs in May 2022. The following information was collected and assessed: Species of animals, dietary fat content, intervention protocol (quercetin), and main results of alterations associated with cardiac change. A total of 116 articles were selected from the database and 30 articles were included in this study. The administration form of quercetin was used in the diet supplemented in 73.4% (n = 22) of the studies. The dosage ranged between 10 and 100 mg/kg, 0.01%-0.36%, and 4-8 g/kg diet. The treatment time ranged between 14 and 63 days in 48.4% studies and most of the selected studies observed changes in the: Serum concentrations of lipids (60%, n = 18) mainly decrease in TC and TG, left ventricle (LV) (16.13%, n = 5) includes attenuation of the cardiac hypertrophy; inhibition of atherosclerotic progression (32%, n = 10) with decrease in lesions and plaque formation; improvement in the expression of gene and protein associated with cardiac functionality and oxidative stress (51.6%; n = 16). Quercetin supplementation at different concentrations/doses promotes important cardioprotective effects in experimental models exposed to a HFD. The supplemented diet was shown to be the better administration option. The methodological variation presented in the articles selected in this review proves that the most appropriate intervention protocol, as well as the most effective route of administration, promotes these effects.

Role of flavonoids in controlling obesity: molecular targets and mechanisms

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

The effects of phytochemicals on serum triglycerides in subjects with hypertriglyceridemia: A systematic review of randomized controlled trials

This systematic review aimed to evaluate the efficacy of phytochemicals on lipid parameters in patients with hypertriglyceridemia (HTG). A comprehensive search was performed in PubMed/Medline, Scopus, ISI Web of Science, and Google Scholar from inception up to October 2021 to recognize randomized controlled trials (RCTs) assessing the effects of phytochemicals on lipid profiles in patients with HTG. Forty-eight RCTs including 53 arms and comprising 3,478 HTG patients met the eligibility criteria. Phytochemicals significantly reduced the serum levels of triglycerides in 32 out 53 arms, total cholesterol in 22 out of 51, low-density lipoprotein cholesterol in 21 out of 48, very low-density lipoprotein cholesterol in 1 out of 5, apolipoprotein B in 2 out of 4, and lipoprotein(a) levels in 2 out of 4 arms. Furthermore, phytochemicals supplementation increased the levels of high-density lipoprotein cholesterol in 15 out of 48 arms. In brief, phytochemicals supplementation might have beneficial effects on HTG. In most of the studies, phytochemicals had a favorable effect on at least one of the lipid parameters.

Thymoquinone and quercetin protect against hepatic steatosis in association with SIRT1/AMPK stimulation and regulation of autophagy, perilipin-2, and cytosolic lipases

BACKGROUND

We sought to investigate thymoquinone (TQ)/quercetin combination in preventing hepatic steatosis (HS).

MATERIALS AND METHODS

The included rat groups; (1) Control, (2) HS model, (3) HS treated with TQ 10 mg.kg^-1.d^-1, (4) HS treated with quercetin 50 mg.kg^-1.d^-1, and (5) HS treated with both compounds for 4 weeks.

RESULTS

TQ/quercetin co-treatment augmented the anti-steatosis potential of each ingredient. The results revealed more (p < 0.001) sirtuin (SIRT1)/AMP-activated protein kinase (p-AMPK) upregulation compared to each treatment in line with autophagy protein Atg7 enhancement, and suppressed pro-inflammatory and oxidation markers. They diminished the hepatic lipogenic enzymes and perilipin-2 and activated the cytosolic lipases adipose triglyceride lipase (ATGL). Histological and Biochemical analysis revealed diminished lipid deposition and improved liver enzymes (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) compared to the data of separate treatments.

CONCLUSION

TQ and quercitin effectively upregulated SIRT1/p-AMPK and regulated hepatic perilipin-2/ATGL, inflammation and oxidative stress, preserved liver structure and function. TQ/quercetin combination additively prevents HS.

The Ameliorative Effect and Mechanisms of Ruditapes philippinarum Bioactive Peptides on Obesity and Hyperlipidemia Induced by a High-Fat Diet in Mice

In this study, bioactive peptides (RBPs) from Ruditapes philippinarum were prepared by fermentation with Bacillus natto and the effect and mechanisms of RBPs on obesity and hyperlipidemia were explored in mice. We found that RBPs significantly reduced body weight, adipose tissue weight, accumulation of hepatic lipids, and serum levels of total cholesterol (CHO), triglyceride (TG), and low-density lipoprotein (LDL). Mechanistic studies showed that RBPs up-regulated the hepatic expression of genes related to lipolysis, such as hormone-sensitive lipase (HSL), phosphorylated AMP-activated protein kinase (p-AMPK), and peroxisome proliferator-activated receptors α (PPARα), and down-regulated the expression of peroxisome proliferator-activated receptors γ (PPARγ) which is related to lipid synthesis. In addition, RBPs could attenuate obesity and hyperlipidemia by regulating disordered gut microbiota composition, such as increasing the abundance of microflora related to the synthesis of short chain fatty acids (SCFAs) (Bacteroidetes, Prevotellaceas_UCG_001, norank_f_Muribaculaceae, and Odoribacter) and controlling those related to intestinal inflammation (reduced abundance of Deferribacteres and increased abundance of Alistipes and ASF356) to exert anti-obesity and lipid-lowering activities. Our findings laid the foundation for the development and utilization of RBPs as a functional food to ameliorate obesity and hyperlipidemia.

Effects of Quercetin on the Intestinal Microflora of Freshwater Dark Sleeper Odontobutis potamophila

Flavonoids have antimicrobial and anti-oxidation properties. The effects of the flavonoid quercetin on the intestinal microflora of freshwater dark sleeper Odontobutis potamophila were tested for the first time. Odontobutis potamophila juveniles were treated with quercetin for 21 days at one of three concentrations (2.5, 5.0, or 10.0 mg/L) and compared with a control group that was not treated with quercetin. Quercetin improved the stability of the intestinal flora in O. potamophila and the probiotic bacteria Bacillus spp. and Lactobacillus spp. increased in species abundance after the low concentration quercetin treatments. Furthermore, the abundance of pathogenic bacteria Plesiomonas spp., Aeromonas spp., and Shewanella spp. decreased after the fish had been exposed to quercetin. Activity of hepatic antioxidant enzymes (superoxide dismutase, SOD), (glutathione S-transferase, GST), (glutathione peroxidase, GSH-Px), and (total antioxidant capacity, T-AOC) increased in the livers of O. potamophila treated with quercetin, thereby increasing their hepatic antioxidant capacity and their ability to scavenge free radicals.

Natural polyphenols: a potential prevention and treatment strategy for metabolic syndrome

Metabolic syndrome (MS) is the term for a combination of hypertension, dyslipidemia, insulin resistance, and central obesity as factors leading to cardiovascular and metabolic disease. Epidemiological investigation has shown that polyphenol intake is negatively correlated with the incidence of MS. Natural polyphenols are widely found in cocoa beans, tea, vegetables, fruits, and some Chinese herbal medicines; they are a class of plant compounds containing a variety of phenolic structural units, which are potent antioxidants and anti-inflammatory agents in plants. Polyphenols are composed of flavonoids (such as flavanols, anthocyanidins, anthocyanins, isoflavones, etc.) and non-flavonoids (such as phenolic acids, stilbenes, and lignans). Modern pharmacological studies have proved that polyphenols can reduce blood pressure, improve lipid metabolism, lower blood glucose, and reduce body weight, thereby preventing and improving MS. Due to the unique characteristics and potential development and application value of polyphenols, this review summarizes some natural polyphenols that could treat MS, including their chemical properties, plant sources, and pharmacological action against MS, to provide a basis for the further study of polyphenols in MS.

A comprehensive review on phytochemicals for fatty liver: are they potential adjuvants?

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome and, as such, is associated with obesity. With the current and growing epidemic of obesity, NAFLD is already considered the most common liver disease in the world. Currently, there is no official treatment for the disease besides weight loss. Although there are a few synthetic drugs currently being studied, there is also an abundance of herbal products that could also be used for treatment. With the World Health Organization (WHO) traditional medicine strategy (2014-2023) in mind, this review aims to analyze the mechanisms of action of some of these herbal products, as well as evaluate toxicity and herb-drug interactions available in literature.

Metronidazole enhances steatosis-related early-stage hepatocarcinogenesis in high fat diet-fed rats through DNA double-strand breaks and modulation of autophagy

Nonalcoholic fatty liver disease is a hepatic disorder with deposition of fat droplets and has a high risk of progression to steatosis-related hepatitis and irreversible hepatic cancer. Metronidazole (MNZ) is an antiprotozoal and antimicrobial agent widely used to treat patients infected with anaerobic bacteria and intestinal parasites; however, MNZ has also been shown to induce liver tumors in rodents. To investigate the effects of MNZ on steatosis-related early-stage hepatocarcinogenesis, male rats treated with N-nitrosodiethylamine following 2/3 hepatectomy at week 3 were received a control basal diet, high fat diet (HFD), or HFD containing 0.5% MNZ. The HFD induced obesity and steatosis in the liver, accompanied by altered expression of Pparg and Fasn, genes related to lipid metabolism. MNZ increased nuclear translocation of lipid metabolism-related transcription factor peroxisome proliferator-activated receptor gamma in hepatocytes, together with altered liver expression of lipid metabolism genes (Srebf1, Srebf2, Pnpla2). Furthermore, MNZ significantly increased the number of preneoplastic liver foci, accompanied by DNA double-strand breaks and late-stage autophagy inhibition, as reflected by increased levels of γ-H2AX, LC3, and p62. Therefore, MNZ could induce steatosis-related hepatocarcinogenesis by inducing DNA double-strand breaks and modulating autophagy in HFD-fed rats.

A Multidrug Approach to Modulate the Mitochondrial Metabolism Impairment and Relative Oxidative Stress in Fanconi Anemia Complementation Group A

Fanconi Anemia (FA) is a rare recessive genetic disorder characterized by aplastic anemia due to a defective DNA repair system. In addition, dysfunctional energy metabolism, lipid droplets accumulation, and unbalanced oxidative stress are involved in FA pathogenesis. Thus, to modulate the altered metabolism, Fanc-A lymphoblast cell lines were treated with quercetin, a flavonoid compound, C75 (4-Methylene-2-octyl-5-oxotetrahydrofuran-3-carboxylic acid), a fatty acid synthesis inhibitor, and rapamycin, an mTOR inhibitor, alone or in combination. As a control, isogenic FA cell lines corrected with the functional Fanc-A gene were used. Results showed that: (i) quercetin recovered the energy metabolism efficiency, reducing oxidative stress; (ii) C75 caused the lipid accumulation decrement and a slight oxidative stress reduction, without improving the energy metabolism; (iii) rapamycin reduced the aerobic metabolism and the oxidative stress, without increasing the energy status. In addition, all molecules reduce the accumulation of DNA double-strand breaks. Two-by-two combinations of the three drugs showed an additive effect compared with the action of the single molecule. Specifically, the quercetin/C75 combination appeared the most efficient in the mitochondrial and lipid metabolism improvement and in oxidative stress production reduction, while the quercetin/rapamycin combination seemed the most efficient in the DNA breaks decrement. Thus, data reported herein suggest that FA is a complex and multifactorial disease, and a multidrug strategy is necessary to correct the metabolic alterations.

Role of Peroxisome Proliferator-Activated Receptors (PPARs) in Energy Homeostasis of Dairy Animals: Exploiting Their Modulation through Nutrigenomic Interventions

Peroxisome proliferator-activated receptors (PPARs) are the nuclear receptors that could mediate the nutrient-dependent transcriptional activation and regulate metabolic networks through energy homeostasis. However, these receptors cannot work properly under metabolic stress. PPARs and their subtypes can be modulated by nutrigenomic interventions, particularly under stress conditions to restore cellular homeostasis. Many nutrients such as polyunsaturated fatty acids, vitamins, dietary amino acids and phytochemicals have shown their ability for potential activation or inhibition of PPARs. Thus, through different mechanisms, all these nutrients can modulate PPARs and are ultimately helpful to prevent various metabolic disorders, particularly in transition dairy cows. This review aims to provide insights into the crucial role of PPARs in energy metabolism and their potential modulation through nutrigenomic interventions to improve energy homeostasis in dairy animals.

Utilizing preclinical models of genetic diversity to improve translation of phytochemical activities from rodents to humans and inform personalized nutrition

Mouse models are an essential tool in different areas of research, including nutrition and phytochemical research. Traditional inbred mouse models have allowed the discovery of therapeutical targets and mechanisms of action and expanded our knowledge of health and disease. However, these models lack the genetic variability typically found in human populations, which hinders the translatability of the results found in mice to humans. The development of genetically diverse mouse models, such as the collaborative cross (CC) or the diversity outbred (DO) models, has been a useful tool to overcome this obstacle in many fields, such as cancer, immunology and toxicology. However, these tools have not yet been widely adopted in the field of phytochemical research. As demonstrated in other disciplines, use of CC and DO models has the potential to provide invaluable insights for translation of phytochemicals from rodents to humans, which are desperately needed given the challenges and numerous failed clinical trials in this field. These models may prove informative for personalized use of phytochemicals in humans, including: predicting interindividual variability in phytochemical bioavailability and efficacy, identifying genetic loci or genes governing response to phytochemicals, identifying phytochemical mechanisms of action and therapeutic targets, and understanding the impact of genetic variability on individual response to phytochemicals. Such insights would prove invaluable for personalized implementation of phytochemicals in humans. This review will focus on the current work performed with genetically diverse mouse populations, and the research opportunities and advantages that these models can offer to phytochemical research.

Nonalcoholic fatty liver disease: The role of quercetin and its therapeutic implications

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease, affecting almost one-third of the general population and 75% of obese patients with type 2 diabetes. The aim of this article is to review the current evidence concerning the role of quercetin, a natural compound and flavonoid, and its possible therapeutic effects on this modern-day disease. Despite the fact that the exact pathophysiological mechanisms through which quercetin has a hepatoprotective effect on NAFLD are still not fully elucidated, this review clearly demonstrates that this flavonoid has potent antioxidative stress action and inhibitory effects on hepatocyte apoptosis, inflammation, and generation of reactive oxygen species, factors which are linked to the development of the disease. NAFLD is closely associated with increased dietary fat consumption, especially in Western countries. The hepatoprotective effect of quercetin against NAFLD merits serious consideration and further validation by future studies.

Effects of Lingonberry (Vaccinium vitis-idaea L.) Supplementation on Hepatic Gene Expression in High-Fat Diet Fed Mice

The prevalence of nonalcoholic fatty liver disease (NAFLD) is growing worldwide in association with Western-style diet and increasing obesity. Lingonberry (Vaccinium vitis-idaea L.) is rich in polyphenols and has been shown to attenuate adverse metabolic changes in obese liver. This paper investigated the effects of lingonberry supplementation on hepatic gene expression in high-fat diet induced obesity in a mouse model. C57BL/6N male mice were fed for six weeks with either a high-fat (HF) or low-fat (LF) diet (46% and 10% energy from fat, respectively) or HF diet supplemented with air-dried lingonberry powder (HF + LGB). HF diet induced a major phenotypic change in the liver, predominantly affecting genes involved in inflammation and in glucose and lipid metabolism. Lingonberry supplementation prevented the effect of HF diet on an array of genes (in total on 263 genes) associated particularly with lipid or glucose metabolic process (such as Mogat1, Plin4, Igfbp2), inflammatory/immune response or cell migration (such as Lcn2, Saa1, Saa2, Cxcl14, Gcp1, S100a10) and cell cycle regulation (such as Cdkn1a, Tubb2a, Tubb6). The present results suggest that lingonberry supplementation prevents HF diet-induced adverse changes in the liver that are known to predispose the development of NAFLD and its comorbidities. The findings encourage carrying out human intervention trials to confirm the results, with the aim of recommending the use of lingonberries as a part of healthy diet against obesity and its hepatic and metabolic comorbidities.

The effect of 24-week continuous intake of quercetin-rich onion on age-related cognitive decline in healthy elderly people: a randomized, double-blind, placebo-controlled, parallel-group comparative clinical trial

Quercetin, a type of flavonoid, is believed to reduce age-related cognitive decline. To elucidate its potential function, we carried out a randomized, double-blind, placebo-controlled, parallel-group comparative clinical trial involving 24-week continuous intake of quercetin-rich onion compared to quercetin-free onion as a placebo. Seventy healthy Japanese individuals (aged 60 to 79 years old) were enrolled in this study. We examined the effect of quercetin-rich onion (the active test food) on cognitive function using the Mini-Mental State Examination, Cognitive Assessment for Dementia iPad version, and Neuropsychiatric Inventory Nursing Home version. The Mini-Mental State Examination scores were significantly improved in the active test food group (daily quercetin intake, 50 mg as aglycone equivalent) compared to the placebo food group after 24 weeks. On the Cognitive Assessment for Dementia iPad version for emotional function evaluation, we found that the scores of the active test food group were significantly improved, suggesting that quercetin prevents cognitive decline by improving depressive symptoms and elevating motivation. On the Neuropsychiatric Inventory Nursing Home version, we found significant effects on reducing the burden on study partners. Taking all the data together, we concluded that 24-week continuous intake of quercetin-rich onion reduces age-related cognitive decline, possibly by improving emotional conditions. Clinical trial register and their clinical registration number: This study was registered with UMIN (approval number UMIN000036276, 5 April 2019).

Modelling Nonalcoholic Steatohepatitis In Vivo-A Close Transcriptomic Similarity Supports the Guinea Pig Disease Model

The successful development of effective treatments against nonalcoholic steatohepatitis (NASH) is significantly set back by the limited availability of predictive preclinical models, thereby delaying and reducing patient recovery. Uniquely, the guinea pig NASH model develops hepatic histopathology and fibrosis resembling that of human patients, supported by similarities in selected cellular pathways. The high-throughput sequencing of guinea pig livers with fibrotic NASH (n = 6) and matched controls (n = 6) showed a clear separation of the transcriptomic profile between NASH and control animals. A comparison to NASH patients with mild disease (GSE126848) revealed a 45.2% overlap in differentially expressed genes, while pathway analysis showed a 34% match between the top 50 enriched pathways in patients with advanced NASH (GSE49541) and guinea pigs. Gene set enrichment analysis highlighted the similarity to human patients (GSE49541), also when compared to three murine models (GSE52748, GSE38141, GSE67680), and leading edge genes THRSP, CCL20 and CD44 were highly expressed in both guinea pigs and NASH patients. Nine candidate genes were identified as highly correlated with hepatic fibrosis (correlation coefficient > 0.8), and showed a similar expression pattern in NASH patients. Of these, two candidate genes (VWF and SERPINB9) encode secreted factors, warranting further investigations as potential biomarkers of human NASH progression. This study demonstrates key similarities in guinea pig and human NASH, supporting increased predictability when translating research findings to human patients.

Quercetin Ameliorates Insulin Resistance and Restores Gut Microbiome in Mice on High-Fat Diets

Quercetin is a flavonoid that has been shown to have health-promoting capacities due to its potent antioxidant activity. However, the effect of chronic intake of quercetin on the gut microbiome and diabetes-related biomarkers remains unclear. Male C57BL/6J mice were fed HF or HF supplemented with 0.05% quercetin (HFQ) for 6 weeks. Diabetes-related biomarkers in blood were determined in mice fed high-fat (HF) diets supplemented with quercetin. Mice fed the HFQ diet gained less body, liver, and adipose weight, while liver lipid and blood glucose levels were also lowered. Diabetes-related plasma biomarkers insulin, leptin, resistin, and glucagon were significantly reduced by quercetin supplementation. In feces, quercetin supplementation significantly increased the relative abundance of Akkermansia and decreased the Firmicutes/Bacteroidetes ratio. The expression of genes Srebf1, Ppara, Cyp51, Scd1, and Fasn was downregulated by quercetin supplementation. These results indicated that diabetes biomarkers are associated with early metabolic changes accompanying obesity, and quercetin may ameliorate insulin resistance.

Cooked Black Turtle Beans Ameliorate Insulin Resistance and Restore Gut Microbiota in C57BL/6J Mice on High-Fat Diets

Colored common beans are associated with health promoting and chronic disease prevention effects. Male C57BL/6J mice were fed high-fat (HF) diets supplemented with cooked black turtle beans (HFB) to prevent obesity related insulin resistance. Mice on both HF and HFB were obese compared to mice fed a low-fat (LF) diet. Plasma low density lipoprotein (LDL) and triglyceride concentrations of mice fed HFB diet were 28% and 36.6% lower than those on HF diet. Homeostatic model assessment of insulin resistance (HOMA-IR) index of mice fed HFB diet was 87% lower than that of mice fed HF diet. Diabetes related biomarkers, gastric inhibitory polypeptide (GIP), leptin, glucagon, and inflammatory cytokines interleukin 4 (IL-4) and IL-5, 10 and 12, IFN-g and TNF-α were significantly affected by HFB diet. Pparα, Cyp7a1 and Fasn were down-regulated by HFB diet while LDL-R, Srebp-2, Adipoq and Slc2a4 were up-regulated by HFB diet. The ratio of Firmicutes/Bacteroidetes (F/B) was also decreased 64.1% by HFB diet compared to HF diet. The results indicated that cooked black turtle bean consumption could ameliorate insulin resistance and lower plasma LDL in mice fed HF diet through glucose signaling pathway and JNK/c-Jun pathway. Meanwhile, cooked black turtle bean consumption restored the gut microbiome.

The Therapeutic Effects and Mechanisms of Quercetin on Metabolic Diseases: Pharmacological Data and Clinical Evidence

Metabolic diseases have become major public health issues worldwide. Searching for effective drugs for treating metabolic diseases from natural compounds has attracted increasing attention. Quercetin, an important natural flavonoid, is extensively present in fruits, vegetables, and medicinal plants. Due to its potentially beneficial effects on human health, quercetin has become the focus of medicinal attention. In this review, we provide a timely and comprehensive summary of the pharmacological advances and clinical data of quercetin in the treatment of three metabolic diseases, including diabetes, hyperlipidemia, and nonalcoholic fatty liver disease (NAFLD). Accumulating evidences obtained from animal experiments prove that quercetin has beneficial effects on these three diseases. It can promote insulin secretion, improve insulin resistance, lower blood lipid levels, inhibit inflammation and oxidative stress, alleviate hepatic lipid accumulation, and regulate gut microbiota disorders in animal models. However, human clinical studies on the effects of quercetin in diabetes, hyperlipidemia, and NAFLD remain scarce. More clinical trials with larger sample sizes and longer trial durations are needed to verify its true effectiveness in human subjects. Moreover, another important issue that needs to be resolved in future research is to improve the bioavailability of quercetin. This review may provide valuable information for the basic research, drug development, and clinical application of quercetin in the treatment of metabolic diseases.

Quercetin as a protective agent for liver diseases: A comprehensive descriptive review of the molecular mechanism

Quercetin is the major representative of the flavonoid subgroup of flavones, with good pharmacological activities for the treatment of liver diseases, including liver steatosis, fatty hepatitis, liver fibrosis, and liver cancer. It can significantly influence the development of liver diseases via multiple targets and multiple pathways via antifat accumulation, anti-inflammatory, and antioxidant activity, as well as the inhibition of cellular apoptosis and proliferation. Despite extensive research on understanding the mechanism of quercetin in the treatment of liver diseases, there are still no targeted therapies available. Thus, we have comprehensively searched and summarized the different targets of quercetin in different stages of liver diseases and concluded that quercetin inhibited inflammation of the liver mainly through NF-κB/TLR/NLRP3, reduced PI3K/Nrf2-mediated oxidative stress, mTOR activation in autophagy, and inhibited the expression of apoptotic factors associated with the development of liver diseases. In addition, quercetin showed different mechanisms of action at different stages of liver diseases, including the regulation of PPAR, UCP, and PLIN2-related factors via brown fat activation in liver steatosis. The compound inhibited stromal ECM deposition at the liver fibrosis stage, affecting TGF1β, endoplasmic reticulum stress (ERs), and apoptosis. While at the final liver cancer stage, inhibiting cancer cell proliferation and spread via the hTERT, MEK1/ERK1/2, Notch, and Wnt/β-catenin-related signaling pathways. In conclusion, quercetin is an effective liver protectant. We hope to explore the pathogenesis of quercetin in different stages of liver diseases through the review, so as to provide more accurate targets and theoretical basis for further research of quercetin in the treatment of liver diseases.

Quercetin enhances fatty acid β-oxidation by inducing lipophagy in AML12 hepatocytes

Recent evidence demonstrated that chronic intake of quercetin attenuated hepatic fat accumulation in various animal models of obesity and diabetes. However, whether quercetin has the ability to enhance energy metabolism in hepatocytes and its exact mechanisms have yet to be identified. In the present study, we investigated whether quercetin directly enhanced the energy metabolism of cultured hepatocytes by focusing on lipophagy, involving selective autophagic degradation of lipid droplets. As an indicator of mitochondrial respiration, oxygen consumption was measured following 12-h treatment with quercetin or its related flavonoids, isorhamnetin and rutin (10 μM) using an extracellular flux analyzer. Treatment of alpha mouse liver 12 (AML12) hepatocytes with quercetin enhanced mitochondrial respiration, but isorhamnetin and rutin did not. Results of a palmitate-bovine serum albumin fatty acid oxidation assay showed that quercetin significantly increased the oxygen consumption of AML12 hepatocytes, suggesting enhanced fatty acid β-oxidation. However, as expression levels of mitochondrial oxidative phosphorylation proteins were unaltered by quercetin, we explored whether lipophagy contributed to enhanced fatty acid β-oxidation. Increased colocalization of lipid droplets and lysosomes confirmed that quercetin promoted lipophagy in AML12 hepatocytes. Furthermore, pharmacological inhibition of the autophagy–lysosomal pathway abolished the enhancement of fatty acid β-oxidation induced by quercetin in AML12 hepatocytes, suggesting that the enhancement of lipophagy by quercetin contributed to increased fatty acid β-oxidation. Finally, we showed that quercetin could activate AMPK signaling, which regulates autophagy even under nutrient-sufficient conditions. Our findings indicate that quercetin enhanced energy metabolism by a potentially novel mechanism involving promotion of lipophagy to produce the substrate for fatty acid β-oxidation in mitochondria through activation of AMPK signaling. Our results suggest the possibility that nutrient-induced lipophagy might contributes to the reduction of fat in hepatocytes.

Quercetin and metabolic syndrome: A review

Metabolic syndrome (MetS) is a complex of diseases that lead to mortality due to the development of cardiovascular problems. Quercetin, as an important flavonoid, has various properties such as decreasing blood pressure, anti-hyperlipidemia, anti-hyperglycemia, anti-oxidant, antiviral, anticancer, anti-inflammatory, anti-microbial, neuroprotective, and cardio-protective effects. In this review article, we collected original articles from different sources such as Google Scholar, Medline, Scopus, and Pubmed, which is related to the effect of quercetin on the improvement of the signs of MetS, including elevated glucose level, hyperlipidemia, obesity, and blood pressure. According to these data, quercetin may also have a role in the management of metabolic disorders via different mechanisms such as increasing adiponectin, decreasing leptin, anti-oxidant activity, reduction of insulin resistance, the elevation of insulin level, and blocking of calcium channel. We have attempted to make some recommendations on the quercetin application in patients. However, it needs to do further clinical trials and more investigations to show the real clinical value of quercetin on metabolic syndrome.

Natural Polyphenols in Metabolic Syndrome: Protective Mechanisms and Clinical Applications

Metabolic syndrome (MetS) is a chronic disease, including abdominal obesity, dyslipidemia, hyperglycemia, and hypertension. It should be noted that the occurrence of MetS is closely related to oxidative stress-induced mitochondrial dysfunction, ectopic fat accumulation, and the impairment of the antioxidant system, which in turn further aggravates the intracellular oxidative imbalance and inflammatory response. As enriched anti-inflammatory and antioxidant components in plants, natural polyphenols exhibit beneficial effects, including improving liver fat accumulation and dyslipidemia, reducing blood pressure. Hence, they are expected to be useful in the prevention and management of MetS. At present, epidemiological studies indicate a negative correlation between polyphenol intake and MetS incidence. In this review, we summarized and discussed the most promising natural polyphenols (including flavonoid and non-flavonoid drugs) in the precaution and treatment of MetS, including their anti-inflammatory and antioxidant properties, as well as their regulatory functions involved in glycolipid homeostasis.

Quercetin and non-alcoholic fatty liver disease: A review based on experimental data and bioinformatic analysis

Quercetin, a polyphenol widely present in the plant kingdom, has received great interest due to pleiotropic effects. As evidenced by animal and cellular studies, quercetin exerts hepatoprotection against non-alcoholic fatty liver disease (NAFLD), particularly in hepatic steatosis and hepatitis. Mechanically, various hypotheses of such protective effects have been actively proposed, including improving fatty acid metabolism, anti-inflammation, anti-oxidant, modulating gut microbiota and bile acid, etc. Here, the role of quercetin in NAFLD was summarized. With a particular focus on molecular mechanism, we comprehensively discussed the pathways of quercetin on NAFLD based on the analysis from Gene Expression Omnibus (GEO) database and experimental evidence.

Anti-obesity properties and mechanism of action of flavonoids: A review

Obesity is a major public health problem, and there is increasing scientific interest in its mechanisms, as well as a search for new compounds with antioxidant and anti-inflammatory properties that can minimize the metabolic complications associated with its pathology. One potential source of these compounds is natural products; Among these, flavonoids are a promising group of natural substances. Flavonoids are active constituents with diverse biological activities and are widely found in plants kingdom. Numerous studies have shown that flavonoids can effectively inhibit obesity and related metabolic disorders. The review synthesizes recent evidence in respect of progress in the understanding of the anti-obesity effects of flavonoids. Such effects which occurs through the modulation of proteins, genes and transcriptional factors involved in decreasing lipogenesis, increasing lipolysis, expenditure energy, stimulating fatty acids B-oxidation, digestion and metabolism of carbohydrates. In addition to mitigating inflammatory responses and suppress oxidative stress. A better understanding of the modulating effects and mechanisms of flavonoids in relation to obesity will allow us to better use these compounds to treat or even prevent obesity and its associated comorbidities.

Content of essential and toxic trace elements in organs of obese Wistar and Zucker leprfa rats receiving quercetin

BACKGROUND

The levels of a number of essential and toxic trace elements in organs and tissues are affected by the disruptions in body homeostasis caused by obesity. Some of these elements may also be influenced by the consumption of biologically active substances of polyphenolic origin, which possess potent abilities to complex with transition metal ions.

AIMS

The aim of this study was to determine the content of essential and toxic trace elements in Wistar outbred and hereditary obese Zucker Lepr^fa (Z) rats consuming a standard balanced diet or hypercaloric diet with excess fat and fructose, supplemented with quercetin or not supplemented.

MATERIALS AND METHODS

Male Wistar and Z rats were fed a control AIN-93M-based semi-synthetic diet or a high-fat-high-carbohydrate diet (HFCD, with 30% fat by weight and 20% fructose provided in the drinking water). A portion of the animals in each line and diet group was administered quercetin at 50 mg/kg body weight. Essential trace elements were included in the diets as a high-purity salt mixture. After the termination of feeding on day 63, the livers, kidneys, and brains of the rats were excised and the content of 16 elements (Fe, Mg, Cu, Mn, Co, Se, Zn, Cr, Ni, Al, Cd, As, Pb, V, Cs, and Ag) was measured by inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

In the livers of the Z rats, the contents of Co, Zn, Mg, Fe, Se, and V were reduced and the content of Cr was increased compared to that of the Wistar rats. Supplementation with quercetin significantly decreased liver Fe, V, and Se content, which was more noticeable in the Wistar rats than in the Z rats. In kidneys of Z rats consuming control diet, the contents of Co, Cu, and Cs were decreased whereas those of Ni, Al, and Se were increased compared with the contents in the Wistar rats. The same trend was observed with HFCD feeding except for Cs content. Quercetin reduced kidney V content in both rat lines fed both diets, whereas it reduced Se and Cs only in the Z rats fed control diet. In the brains of the Z rats, a large increase was observed in some trace elements including Pb, Cd, Al, Cr, Ni, Fe, and V compared with the levels in the Wistar rat brains. Supplementation of the control diet with quercetin decreased Al and Ni in the brains of the Z rats.

CONCLUSION

There were significant differences in the mineral content of organs between the Wistar and Z rats, with different propensities for obesity. Moreover some of these effects had no straightforward association with decreased feed consumption or hepatic fat accumulation. When introduced into the diets, quercetin affected the content of essential and toxic elements, but with ambiguous physiological significance. Thus, indicators of essential and toxic trace elements deserve to be used in the protocols of preclinical as well as clinical trials of biologically active substances and food supplements.

Tiliacora triandra (Colebr.) Diels Leaf Aqueous Extract Inhibits Hepatic Glucose Production in HepG2 Cells and Type 2 Diabetic Rats

This study investigated the effects of Tiliacora triandra (Colebr.) Diels aqueous extract (TTE) on hepatic glucose production in hepatocellular carcinoma (HepG2) cells and type 2 diabetic (T2DM) conditions. HepG2 cells were pretreated with TTE and its major constituents found in TTE, epicatechin (EC) and quercetin (QC). The hepatic glucose production was determined. The in vitro data were confirmed in T2DM rats, which were supplemented daily with 1000 mg/kg body weight (BW) TTE, 30 mg/kg BW metformin or TTE combined with metformin for 12 weeks. Results demonstrate that TTE induced copper-zinc superoxide dismutase, glutathione peroxidase and catalase genes, similarly to EC and QC. TTE decreased hepatic glucose production by downregulating phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) and increasing protein kinase B and AMP-activated protein kinase phosphorylation in HepG2 cells. These results correlated with the antihyperglycemic, antitriglyceridemic, anti-insulin resistance, and antioxidant activities of TTE in T2DM rats, similar to the metformin and combination treatments. Consistently, impairment of hepatic gluconeogenesis in T2DM rats was restored after single and combined treatments by reducing PEPCK and G6Pase genes. Collectively, TTE could potentially be developed as a nutraceutical product to prevent glucose overproduction in patients with obesity, insulin resistance, and diabetes who are being treated with antidiabetic drugs.

Protocatechuic acid and quercetin glucosides in onions attenuate changes induced by high fat diet in rats

Yellow onion waste from industrial peeling was used to obtain three pure preparations: protocatechuic acid (PA), quercetin diglycosides (QD) and quercetin monoglycosides (QM). PA contained 61% protocatechuic acid, QD contained 35% quercetin diglucosides, mainly quercetin-3,4'-diglucoside, and QM contained 41% monoglucosides, mainly quercetin-4'-glucoside. The highest antioxidant activity was shown by PA. The effects of preparations on the digestive functions of the gastrointestinal tract of rats as well as the biochemical parameters and antioxidant capacity of the blood in model research on Wistar rats sustained by a high-fat diet were assessed (5 groups per 8 animals). The results of the present experiment showed that different onion phenolic preparations differently modulated the enzymatic activity of faecal (P < 0.001) and caecal (P < 0.001) microbiota. For instance, the QD preparation but not QM efficiently reduced the faecal and caecal bacterial β-glucuronidase activity. Both protocatechuic acid and quercetin monoglycosides showed a beneficial effect by regulating blood lipids (reduction of TC (P < 0.001) and TG (P < 0.001), non-HDL increase in HDL (P < 0.001)), thereby lowering the risk factors for atherosclerotic lesions AI (P = 0.038) and AII (P = 0.013). In addition, onion phenols showed a strong antioxidant effect, however, with a different mechanism: protocatechuic acid via serum ACL (P = 0.033) increase and hepatic GSSG (P = 0.070) decrease, QM via ACW (P < 0.001) increase and hepatic TBARS (P = 0.002) decrease, and QD via serum ACW increase and hepatic GSSG decrease. It can be concluded that onion polyphenols with a lower molar weight, i.e. QM more preferably affect the blood lipid profile than QD. However QD more efficiently reduced the faecal and caecal bacterial β-glucuronidase activity.

Combined Effect of Quercetin and Fish Oil on Oxidative Stress in the Liver of Mice Fed a Western-Style Diet

To study the combined effect of the flavonoid quercetin and fish oil containing ω-3 fatty acids on preventing diet-induced metabolic syndrome, we fed mice with a control diet, a high-fat, high-sucrose, and high-cholesterol Western-style diet (Western diet), a Western diet supplemented with 0.05% quercetin, a Western diet containing 5% fish oil rich in docosahexaenoic acid (DHA) (DHA diet), or a DHA diet supplemented with 0.05% quercetin. After 18 weeks of feeding, fish oil potentiated the suppression of lipid peroxidation by quercetin in the liver but not in the epididymal adipose tissue. Fish oil but not quercetin suppressed the accumulation of non-esterified fatty acids and the expression of fatty acid synthase in the liver of Western-diet-fed mice. Thus, the combination of quercetin and DHA-rich fish oil may partly alleviate non-alcoholic fatty liver disease by reducing oxidative stress and suppressing fatty acid synthesis.

[Full transcriptome analysis of gene expression in liver of mice in a comparative study of quercetin efficiency on two obesity models]

BACKGROUND

Quercetin (Q; 3,3',4',5,7 - pentahydroxyflavone) can help alleviate the pathological effects of nutritional obesity and metabolic syndrome when taken as part of products for special dietary needs and food supplements. The mechanisms of action of Q at the genetic level are not well understood.

AIMS

To study gene expression in liver tissue of mice with alimentary and genetically determined obesity upon intake of Q with diet.

MATERIALS AND METHODS

During 46 days of the experiment on 32 male C57Bl/6J mice fed a diet with an excess of fat and fructose and 24 male genetically obese db/db mice the effect of Q in dose of 25 or 100 mg/kg of body weight was studied on differential expression of 39430 genes in mice livers by full transcriptome profiling on microchip according to the Agilent One-Color Microarray-Based Gene Expression Analysis Low Input Quick Amp Labeling protocol (version 6.8). To identify metabolic pathways (KEGGs) that were targets of Q exposure, transcriptomic data were analyzed using bioinformatics methods in an "R" environment.

RESULTS

Differences were revealed in the nature of Q supplementation action in animals with dietary induced and genetically determined obesity on a number of key metabolic pathways, including the metabolism of lipids and steroids (Saa3, Cidec, Scd1, Apoa4, Acss2, Fabp5, Car3, Acacb, Insig2 genes), amino acids and nitrogen bases (Ngef, Gls2), carbohydrates (G6pdx, Pdk4), regulation of cell growth, apoptosis and proliferation (Btg3, Cgref1, Fst, Nrep Tuba8), neurotransmission (Grin2d, Camk2b), immune system reactions (CD14i, Jchain, Ifi27l2b).

CONCLUSIONS

The data obtained help to explain the ambiguous effectiveness of Q, like other polyphenols, in the dietary treatment of various forms of obesity in humans, as well as to form a set of sensitive biomarkers that allow us to elucidate the effectiveness of minor biologically active food substances in preclinical trials of new means of metabolic correction of obesity and metabolic syndrome.

Silencing HIF-1α aggravates non-alcoholic fatty liver disease in vitro through inhibiting PPAR-α/ANGPTL4 singling pathway

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is an aberrant lipid metabolism disease. Hypoxia inducible factor-1 (HIF-1α) is a transcription factor which plays an important part in adapting lower oxygen condition. Here, we aimed to clarify the relationship between HIF-1α and NAFLD.

METHODS

HepG2 cells was stimulated by oleic acid (OA) and palmitic acid (PA) to establish in vitro model of NAFLD. The expression of lipid metabolism-related genes, the binding of PPARα to HIF-1α promoter, the lipid deposition, and oxidative stress were detected by qRT-PCR, western blot, Chip assay, Oil Red O staining and ELISA assays, respectively.

RESULTS

HIF-1α silence promoted lipid accumulation in NAFLD cells, accompanying by the significantly increased contents of TG (triglyceride) and ApoB (apolipoprotein B). In HepG2 cells treated with OA/PA, the expression of lipid metabolism-related genes and proteins, including APOE, A2m, TNFRSF11B, LDLr, and SREBP2, and the intracellular lipid deposition were up-regulated and further aggravated after silencing HIF-1α. In addition, the loss of HIF-1α could remarkably elevate MDA contents while inhibit the activities of beneficial antioxidant enzymes SOD and GSH-Px to activate oxidative stress, and promote the secretion of pro-inflammatory IL-6 and TNF-α to aggravate inflammation in NDFLD cells. PPARα positively bound to HIF-1α promoter. The silence of PPARα aggravated lipid deposition under normal or hypoxic environment in NAFLD cells. In addition, PPAR-α silence could decrease the expression of HIF-1α and ANGPTL4 in NAFLD cell model; moreover, the expression of APOE, A2m and TNFRSF11B and the production of TG and MDA were increased by PPAR-α suppression.

CONCLUSION

HIF-1α plays a crucial role in the regulation of lipid metabolism through activating PPAR-α/ANGPTL4 signaling pathway in NAFLD.

Neural Underpinnings of Obesity: The Role of Oxidative Stress and Inflammation in the Brain

Obesity prevalence is increasing at an unprecedented rate throughout the world, and is a strong risk factor for metabolic, cardiovascular, and neurological/neurodegenerative disorders. While low-grade systemic inflammation triggered primarily by adipose tissue dysfunction is closely linked to obesity, inflammation is also observed in the brain or the central nervous system (CNS). Considering that the hypothalamus, a classical homeostatic center, and other higher cortical areas (e.g. prefrontal cortex, dorsal striatum, hippocampus, etc.) also actively participate in regulating energy homeostasis by engaging in inhibitory control, reward calculation, and memory retrieval, understanding the role of CNS oxidative stress and inflammation in obesity and their underlying mechanisms would greatly help develop novel therapeutic interventions to correct obesity and related comorbidities. Here we review accumulating evidence for the association between ER stress and mitochondrial dysfunction, the main culprits responsible for oxidative stress and inflammation in various brain regions, and energy imbalance that leads to the development of obesity. Potential beneficial effects of natural antioxidant and anti-inflammatory compounds on CNS health and obesity are also discussed.

Quercetin Improving Lipid Metabolism by Regulating Lipid Metabolism Pathway of Ileum Mucosa in Broilers

This study is aimed at evaluating the regulatory mechanism of quercetin on lipid metabolism in the ileum of broilers to better understand these pathways decreasing abdominal fat. 480 chickens were randomly divided into 4 groups (control, 0.02% quercetin, 0.04% quercetin, and 0.06% quercetin). Breast muscle, thigh muscle, and abdominal fat pad were removed and weighed at 42 d of age. Serum was obtained by centrifuging blood samples from the jugular vein (10 ml) to determine high-density lipoprotein (HDL), total cholesterol (TC), low-density lipoprotein (LDL), triglyceride (TG), leptin, and adiponectin using ELISA. About 5 g of the ileum was harvested and immediately frozen in liquid nitrogen for RNA-seq. Then, the confirmation of RNA-seq results by the Real-Time Quantitative PCR (RT-qPCR) method was evaluated using Pearson's correlation. Compared with control, abdominal fat percentage was significantly decreased with increasing quercetin supplementation, and the best result was obtained at 0.06% dietary quercetin supplementation (P < 0.01). Breast muscle percentage was significantly decreased at 0.02% quercetin (P < 0.01), and thigh muscle percentage tended to increase (P = 0.078). Meanwhile, 0.04% and 0.06% quercetin significantly decreased TG (P < 0.01), TC (P < 0.01), and LDL content (P < 0.05) in serum. Serum leptin and adiponectin contents were significantly increased by 0.04% and 0.06% dietary quercetin supplementation, compared with the control (P < 0.01). Analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database were used to identify differently expressed genes and lipid metabolism pathways. Quercetin decreased abdominal fat percentage through regulating fat digestion and absorption, glycerophospholipid metabolism, AMPK signaling pathway, fatty acid degradation, and cholesterol metabolism.

Quercetin metabolites from Hibiscus sabdariffa contribute to alleviate glucolipotoxicity-induced metabolic stress in vitro

Polyphenols from Hibiscus sabdariffa (HS) alleviate obesity-related metabolic complications but the metabolites responsible for such effects are unknown. We aimed to elucidate which of the potential plasma metabolites from a polyphenol-enriched HS (PEHS) extract contributed for the reversion of glucolipotoxicity-induced metabolic stress using 3T3-L1 adipocyte and INS 832/13 pancreatic β-cell models under glucolipotoxic conditions. PEHS extract, quercetin (Q) and quercetin-3-O-glucuronide (Q3GA) showed stronger capacity to decrease glucolipotoxicity-induced ROS generation than ascorbic acid or chlorogenic acid. PEHS extract, Q and Q3GA decreased secretion of cytokines (leptin, TNF-α, IGF-1, IL-6, VEGF, IL-1α, IL-1β and CCL2) and reduced CCL2 expression at transcriptional level. In addition, PEHS extract, Q and Q3GA reduced triglyceride accumulation, which occurred through fatty acid synthase (FASN) downregulation, AMPK activation and mitochondrial mass and biogenesis restoration via PPARα upregulation. Electron microscopy confirmed that PEHS extract and Q3GA decreased mitochondrial remodeling and mitophagy. Virtual screening leads us to postulate that Q and Q3GA might act as agonists of these protein targets at specific sites. These data suggest that Q and Q3GA may be the main responsible compounds for the capacity of PEHS extract to revert glucolipotoxicity-induced metabolic stress through AMPK-mediated decrease in fat storage and increase in fatty acid oxidation, though other compounds of the extract may contribute to this capacity.

Interaction of Polyphenols as Antioxidant and Anti-Inflammatory Compounds in Brain-Liver-Gut Axis

Oxidative stress plays an important role in the onset as well as the progression of inflammation. Without proper intervention, acute inflammation could progress to chronic inflammation, resulting in the development of inflammatory diseases. Antioxidants, such as polyphenols, have been known to possess anti-oxidative properties which promote redox homeostasis. This has encouraged research on polyphenols as potential therapeutics for inflammation through anti-oxidative and anti-inflammatory pathways. In this review, the ability of polyphenols to modulate the activation of major pathways of inflammation and oxidative stress, and their potential to regulate the activity of immune cells are examined. In addition, in this review, special emphasis has been placed on the effects of polyphenols on inflammation in the brain–liver–gut axis. The data derived from in vitro cell studies, animal models and human intervention studies are discussed.

Prevention effect of quercetin and its glycosides on obesity and hyperglycemia through activating AMPKα in high-fat diet-fed ICR mice

Quercetin and its glycosides possess various health beneficial functions, but comparative study of them on energy metabolism in different tissues are not well studied. In this study, we investigated AMP-activated protein kinase regulated glucose metabolism in the skeletal muscle and lipid metabolism in the white adipose tissue and liver to compare the effectiveness of quercetin and its glycosides, namely isoquercitrin, rutin, and enzymatically modified isoquercitrin, in male ICR mice. The mice were fed a standard or high-fat diet supplemented with 0.1% quercetin and its glycosides for 13 weeks. Quercetin glycosides, but not quercetin, decreased body weight gain and fat accumulation in the mesenteric adipose tissue in high-fat groups. All compounds decreased high-fat diet-increased plasma glucose and insulin levels. Moreover, all compounds significantly increased AMP-activated protein kinase phosphorylation in either standard or high-fat diet-fed mice in all tissues tested. As its downstream events, all compounds induced glucose transporter 4 translocation in the muscle. In the white adipose tissue and liver, all compounds increased lipogenesis while decreased lipolysis. Moreover, all compounds increased browning markers and decreased differentiation markers in adipose tissue. Therefore, quercetin and its glycosides are promising food components for prevention of adiposity and hyperglycemia through modulating AMP-activated protein kinase-driven pathways.

From Environment to Genome and Back: A Lesson from HFE Mutations

The environment and the human genome are closely entangled and many genetic variations that occur in human populations are the result of adaptive selection to ancestral environmental (mainly dietary) conditions. However, the selected mutations may become maladaptive when environmental conditions change, thus becoming candidates for diseases. Hereditary hemochromatosis (HH) is a potentially lethal disease leading to iron accumulation mostly due to mutations in the HFE gene. Indeed, homozygosity for the C282Y HFE mutation is associated with the primary iron overload phenotype. However, both penetrance of the C282Y variant and the clinical manifestation of the disease are extremely variable, suggesting that other genetic, epigenetic and environmental factors play a role in the development of HH, as well as, and in its progression to end-stage liver diseases. Alcohol consumption and dietary habits may impact on the phenotypic expression of HFE-related hemochromatosis. Indeed, dietary components and bioactive molecules can affect iron status both directly by modulating its absorption during digestion and indirectly by the epigenetic modification of genes involved in its uptake, storage and recycling. Thus, the premise of this review is to discuss how environmental pressures led to the selection of HFE mutations and whether nutritional and lifestyle interventions may exert beneficial effects on HH outcomes and comorbidities.

Identifying potential active components of walnut leaf that action diabetes mellitus through integration of UHPLC-Q-Orbitrap HRMS and network pharmacology analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Walnut leaf (WL) is a hypoglycemic herbal medication with blood glucose-lowering activity that can affect diabetes mellitus (DM). However, the active components of WL and the mechanisms by which these compounds affect DM are unclear.

AIM OF STUDY

This study aimed to determine these effective ingredients and elucidate the potential mechanisms by which they affect DM via ultra-high performance liquid chromatography-hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) coupled with network pharmacology analysis.

MATERIALS AND METHODS

First, UHPLC-Q-Orbitrap HRMS was utilized to identify components of WL. Second, the putative targets of the components were identified and predicted based on chemical similarity and online databases. Third, the key candidate targets and potential active components were identified through topological analysis of a component-disease target interaction network. Finally, interactions between active components and therapeutic targets were confirmed by molecular docking analysis.

RESULTS

One hundred and thirty components were identified in WL, among which 38 were considered potentially bioactive, as they showed hypoglycemic effects. Among these 38, 8 key active components possessed high similarities and shared 4 targets with approved drugs. These findings were confirmed by molecular docking analysis.

CONCLUSION

The approach combining UHPLC-Q-Orbitrap HRMS with network pharmacology analysis is a rapid and effective tool to identify potentially bioactive constituents in medicinal plants and prescriptions.

Protective effects of quercetin against oxidative stress induced by bisphenol-A in rat cardiac mitochondria

Research has shown a relationship between the exposures to a chemical agent called bisphenol-A (BPA), which is extensively used in the production of polycarbonate plastics and the incidence of cardiovascular diseases. This association is most likely caused by the BPA's ability to disrupt multiple cardiac mechanisms, including mitochondrial functions. Therefore, this study aimed to explore the ability of quercetin (QUER) to limit the cardiotoxic effect of BPA in the rat's cardiac mitochondria. The experiment was carried out on 32 male Wistar rats, which were randomly assigned to four groups. The negative control group received olive oil; the positive control group received olive oil plus BPA (250 mg/kg); the third group received olive oil, BPA, and QUER (75 mg/kg); and the fourth group received olive oil and QUER, all orally for 14 days. The rats were slaughtered 24 h after the last treatment. The measured parameters included creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) as the biomarkers of cardiotoxicity, triglyceride (TG), total cholesterol (TC), and low-density and high-density lipoprotein cholesterol (LDL-C and HDL-C) as the measures of dyslipidemia, glutathione (GSH) content, catalase activity (CAT), reactive oxygen species (ROS), lipid peroxidation (LPO), and the level of damage to the mitochondrial membranes as the indicators of the impact of QUER on the BPA cardiotoxic effect. Finally, the rats treated with QUER showed better results in terms of serum CK-MB, serum LDH, serum lipid profile, GSH level, CAT activity, mitochondrial membrane potential (ΔΨm), LPO, and ROS. According to the results, QUER could be used as a protective agent against BPA-induced mitochondrial toxicity.

Role of diets and exercise in ameliorating obesity-related hepatic steatosis: Insights at the microRNA-dependent thyroid hormone synthesis and action

AIMS

The present study was designed to compare the effects of a low-fat diet (LF), calorie restriction (CR), quercetin (Que) and exercise (Ex) on hepatic steatosis in a high-fat (HF) diet-induced obesity prone (OP) model in the perspective of microRNA (miR)-dependent thyroid hormone (TH) synthesis and action.

MAIN METHODS

Male C57BL/6J mice were administered a HF diet for 10 weeks to induce OP phenotype and then divided into 5 groups, HF diet (OP-HF), LF diet (OP-LF), 70% CR (OP-CR), 0.05% Que (OP-Que) and a treadmill exercise regimen (OP-Ex); one additional group fed LF diet served as control (LF). 7 weeks later, serum indexes, metabolic alterations, redox status and histological appearance in the thyroid and liver, and TH related miRs with their targets expressions were determined.

KEY FINDINGS

No significance on T3 levels was observed among the six groups. LF, CR, Que and Ex significantly ameliorated HF-induced hepatic steatosis to varying degrees, inhibited T4 production via differentially elevating miR-339, miR-383 and miR-146b to decrease NIS expression and regulating miR-200a/Nrf2 to maintain redox status in the thyroid. Furthermore, these four interventions differentially and significantly decreased miR-383 and miR-146b to elevate TRb and DIO1 expression, and subsequent TH responsive lipid metabolism genes regulation. Among them, the effects of CR on hepatic steatosis were the most prominent.

SIGNIFICANCE

Our data indicated that amelioration of hepatic steatosis by LF, CR, Que and Ex resulted in many shared, but also many differential changes in the miR-dependent TH production and action.