Regressive Effect of Myricetin on Hepatic Steatosis in Mice Fed a High-Fat Diet

Unlocking the Pharmacological Potential of Myricetin Against Various Pathogenesis

Myricetin is a natural flavonoid with powerful antioxidant and anti-inflammatory potential commonly found in vegetables, fruits, nuts, and tea. The vital role of this flavonoid in the prevention and treatment of various diseases is evidenced by its ability to reduce inflammation and oxidative stress, maintain tissue architecture, and modulate cell signaling pathways. Thus, this review summarizes recent evidence on myricetin, focusing precisely on its mechanisms of action in various pathogenesis, including obesity, diabetes mellitus, arthritis, osteoporosis, liver, neuro, cardio, and reproductive system-associated pathogenesis. Moreover, it has been revealed that myricetin exhibits anti-microbial properties due to obstructive virulence factors, preventing biofilm formation and disrupting membrane integrity. Additionally, synergistic potential with other drugs and the role of myricetin-based nanoformulations in different diseases are properly discussed. This review seeks to increase the understanding of myricetin's pharmacological potential in various diseases, principally highlighting its effective mechanisms of action. Further wide-ranging research, as well as more randomized and controlled clinical trial studies, should be executed to reconnoiter this compound's therapeutic value, safety, and usefulness against various human pathogenesis.

Advances in Leaf Plant Bioactive Compounds: Modulation of Chronic Inflammation Related to Obesity

Over the years, there has been a tendency for an increase in global obesity. The World Health Organization's (WHO) 2024 report states that in 2019, more than one billion people were obese, and this condition was responsible for five million deaths, being that obesity is more prevalent among adults compared to adolescents and children. Obesity is a chronic disease characterized by alterations in adipose tissue. When excessive food is consumed and energy expenditure is low, adipose tissue undergoes hypertrophy and hyperplasia. This process activates B cells and induces the transition of anti-inflammatory M2-like macrophages into pro-inflammatory M1-like macrophages. B cells, acting as inflammatory mediators, stimulate pro-inflammatory CD8+ T cells, and promote macrophage infiltration into tissues. This condition triggers inflammation, increases oxidative stress, and ultimately leads to cellular death. During inflammation, an increase of pro-inflammatory cytokines occurs along with a decrease of anti-inflammatory cytokines. By contrast, the increase of oxidative stress is related to an increase of reactive oxygen species (ROS), oxidation of biomolecules, and a decrease in antioxidants. This mechanism for obesity can be mitigated through several healthy lifestyle changes, primarily including regular physical activity and healthy eating. These factors help reduce pro-inflammatory mediators and ROS, lowering inflammation and oxidative stress. Therefore, this review article focuses on studying the bioactive compounds present in the edible leaves of Annona cherimola Mill., Ipomoea batata (L.) Poir., Colocasia esculenta (L.) Schott, Eriobotrya japonica, Cymbopogon citratus, Psidium guajava (L.), and Smallanthus sonchifolius to evaluate their effects on the mechanisms involved in obesity.

The protective effects and mechanism of myricetin in liver diseases (Review)

Liver diseases have become one of the significant threats to global health. However, there is a lack of effective targeted therapeutic drugs in this field and the existing drugs used for liver disease treatment usually have side‑effects. Traditional Chinese medicine (TCM) has the distinctive advantages of multi‑target and low side‑effects. As a flavonoid with various pharmacological activities such as anti‑tumour, anti‑oxidant, anti‑inflammatory and anti‑bacterial, the TCM myricetin has been widely used in liver disease research. The present work focuses on the role and molecular mechanism of myricetin in liver diseases such as acute liver injury, fatty liver, liver fibrosis and hepatocellular carcinoma. It is a promising reference for further research and application of myricetin in the treatment of liver diseases.

Metabolic dysfunction-associated steatotic liver disease-induced changes in the antioxidant system: a review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a heterogeneous condition characterized by liver steatosis, inflammation, consequent fibrosis, and cirrhosis. Chronic impairment of lipid metabolism is closely related to oxidative stress, leading to cellular lipotoxicity, mitochondrial dysfunction, and endoplasmic reticulum stress. The detrimental effect of oxidative stress is usually accompanied by changes in antioxidant defense mechanisms, with the alterations in antioxidant enzymes expression/activities during MASLD development and progression reported in many clinical and experimental studies. This review will provide a comprehensive overview of the present research on MASLD-induced changes in the catalytic activity and expression of the main antioxidant enzymes (superoxide dismutases, catalase, glutathione peroxidases, glutathione S-transferases, glutathione reductase, NAD(P)H:quinone oxidoreductase) and in the level of non-enzymatic antioxidant glutathione. Furthermore, an overview of the therapeutic effects of vitamin E on antioxidant enzymes during the progression of MASLD will be presented. Generally, at the beginning of MASLD development, the expression/activity of antioxidant enzymes usually increases to protect organisms against the increased production of reactive oxygen species. However, in advanced stage of MASLD, the expression/activity of several antioxidants generally decreases due to damage to hepatic and extrahepatic cells, which further exacerbates the damage. Although the results obtained in patients, in various experimental animal or cell models have been inconsistent, taken together the importance of antioxidant enzymes in MASLD development and progression has been clearly shown.

Efficacy of Myricetin Supplementation on Glucose and Lipid Metabolism: A Systematic Review and Meta-Analysis of In Vivo Mice Studies

BACKGROUND/OBJECTIVES

Type 2 diabetes mellitus (T2DM) is a disorder characterized by insulin resistance, hyperglycemia, and dyslipidemia. Myricetin, a flavonoid found in various plants, has shown potential anti-diabetic effects in murine studies. This meta-analysis aimed to evaluate the impact of myricetin supplementation on glucose metabolism and lipid profiles in mouse models of metabolic diseases.

METHODS

A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines (PROSPERO: CRD42024591569). Studies involving mice with metabolic disease models and exclusively using myricetin supplementation were checked across four databases (Embase, Scopus, PubMed, and WoS) until 23rd September 2024. The primary outcomes assessed were blood glucose (BG), insulin levels, triacylglycerol (TAG), total cholesterol (TC), HDL, and LDL. A random-effects model was applied to estimate standardized mean differences (SMD), and SYRCLE's risk-of-bias tool for animal studies was used.

RESULTS

Twenty-one studies with 514 mice met the inclusion criteria. Myricetin supplementation significantly reduced BG (SMD = -1.45, CI: -1.91 to -0.99, p < 0.00001, I2 = 74%), insulin (SMD = -1.78, CI: -2.89 to -0.68, p = 0.002, I2 = 86%), TAG (SMD = -2.60, CI: -3.24 to -1.96, p < 0.00001, I2 = 81%), TC (SMD = -1.86, CI: -2.29 to -1.44, p < 0.00001, I2 = 62%), and LDL (SMD = -2.95, CI: -3.75 to -2.14, p < 0.00001, I2 = 74%). However, the effect on HDL was not statistically significant (SMD = 0.71, CI: -0.01 to 1.43, p = 0.05, I2 = 83%).

CONCLUSIONS

Myricetin supplementation improved glucose metabolism and lipid profiles in mouse models, suggesting its potential as a therapeutic agent for managing T2DM. However, further research is needed to confirm these findings in human studies.

Berberine directly targets AKR1B10 protein to modulate lipid and glucose metabolism disorders in NAFLD

ETHNOPHARMACOLOGICAL RELEVANCE

Berberine (BBR) is the main active component from Coptidis rhizome, a well-known Chinese herbal medicine used for metabolic diseases, especially diabetes for thousands of years. BBR has been reported to cure various metabolic disorders, such as nonalcoholic fatty liver disease (NAFLD). However, the direct proteomic targets and underlying molecular mechanism of BBR against NAFLD remain less understood.

AIM OF THE STUDY

To investigate the direct target and corresponding molecular mechanism of BBR on NAFLD is the aim of the current study.

MATERIALS AND METHODS

High-fat diet (HFD)-fed mice and oleic acid (OA) stimulated HepG2 cells were utilized to verify the beneficial impacts of BBR on glycolipid metabolism profiles. The click chemistry in proteomics, DARTS, CETSA, SPR and fluorescence co-localization analysis were conducted to identify the targets of BBR for NAFLD. RNA-seq and shRNA/siRNA were used to investigate the downstream pathways of the target.

RESULTS

BBR improved hepatic steatosis, ameliorated insulin resistance, and reduced TG levels in the NAFLD models. Importantly, Aldo-keto reductase 1B10 (AKR1B10) was first proved as the target of BBR for NAFLD. The gene expression of AKR1B10 increased significantly in the NAFLD patients' liver tissue. We further demonstrated that HFD and OA increased AKR1B10 expression in the C57BL/6 mice's liver and HepG2 cells, respectively, whereas BBR decreased the expression and activities of AKR1B10. Moreover, the knockdown of AKR1B10 by applying shRNA/siRNA profoundly impacted the beneficial effects on the pathogenesis of NAFLD by BBR. Meanwhile, the changes in various proteins (ACC1, CPT-1, GLUT2, etc.) are responsible for hepatic lipogenesis, fatty acid oxidation, glucose uptake, etc. by BBR were reversed by the knockdown of AKR1B10. Additionally, RNA-seq was used to identify the downstream pathway of AKR1B10 by examining the gene expression of liver tissues from HFD-fed mice. Our findings revealed that BBR markedly increased the protein levels of PPARα while downregulating the expression of PPARγ. However, various proteins of PPAR signaling pathways remained unaffected post the knockdown of AKR1B10.

CONCLUSIONS

BBR alleviated NAFLD via mediating PPAR signaling pathways through targeting AKR1B10. This study proved that AKR1B10 is a novel target of BBR for NAFLD treatment and helps to find new targets for the treatment of NAFLD by using active natural compounds isolated from traditional herbal medicines as the probe.

Therapeutic potential of traditional Chinese medicine in the prevention and treatment of digestive inflammatory cancer transformation: Portulaca oleracea L. as a promising drug

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been used for centuries to treat various types of inflammation and tumors of the digestive system. Portulaca oleracea L. (POL), has been used in TCM for thousands of years. The chemical composition of POL is variable and includes flavonoids, alkaloids, terpenoids and organic acids and other classes of natural compounds. Many of these compounds exhibit powerful anti-inflammatory and anti-cancer-transforming effects in the digestive system.

AIM OF STUDY

In this review, we focus on the potential therapeutic role of POL in NASH, gastritis and colitis and their associated cancers, with a focus on the pharmacological properties and potential mechanisms of action of the main natural active compounds in POL.

METHODS

The information and data on Portulaca oleracea L. and its main active ingredients were collated from various resources like ethnobotanical textbooks and literature databases such as CNKI, VIP (Chinese literature), PubMed, Science Direct, Elsevier and Google Scholar (English literatures), Wiley, Springer, Tailor and Francis, Scopus, Inflibnet.

RESULTS

Kaempferol, luteolin, myricetin, quercetin, genistein, EPA, DHA, and melatonin were found to improve NASH and NASH-HCC, while kaempferol, apigenin, luteolin, and quercetin played a therapeutic role in gastritis and gastric cancer. Apigenin, luteolin, myricetin, quercetin, genistein, lupeol, vitamin C and melatonin were found to have therapeutic effects in the treatment of colitis and its associated cancers. The discovery of the beneficial effects of these natural active compounds in POL supports the idea that POL could be a promising novel candidate for the treatment and prevention of inflammation-related cancers of the digestive system.

CONCLUSION

The discovery of the beneficial effects of these natural active compounds in POL supports the idea that POL could be a promising novel candidate for the treatment and prevention of inflammation-related cancers of the digestive system. However, clinical data describing the mode of action of the naturally active compounds of POL are still lacking. In addition, pharmacokinetic data for POL compounds, such as changes in drug dose and absorption rates, cannot be extrapolated from animal models and need to be measured in patients in clinical trials. On the one hand, a systematic meta-analysis of the existing publications on TCM containing POL still needs to be carried out. On the other hand, studies on the hepatic and renal toxicity of POL are also needed. Additionally, well-designed preclinical and clinical studies to validate the therapeutic effects of TCM need to be performed, thus hopefully providing a basis for the validation of the clinical benefits of POL.

Unveiling myricetin's pharmacological potency: A comprehensive exploration of the molecular pathways with special focus on PI3K/AKT and Nrf2 signaling

Myricetin can be found in the traditional Chinese medicinal plant, Myrica rubra. Myricetin is a flavonoid that is present in many vegetables, fruits, and plants and is considered to have strong antioxidant properties as well as a wide range of therapeutic applications. Growing interest has been piqued by its classification as a polyphenolic molecule because of its potential therapeutic benefits in both the prevention and management of numerous medical conditions. To clarify myricetin's traditional medical uses, modern research has investigated various pharmacological effects such as antioxidant, anticancer, anti-inflammation, antiviral, antidiabetic, immunomodulation, and antineurodegenerative effects. Myricetin shows promise as a nutritional flavonol that could be beneficial in the prevention and mitigation of prevalent health conditions like diabetes, cognitive decline, and various types of cancer in humans. The findings included in this study indicate that myricetin has a great deal of promise for application in the formulation of medicinal products and nutritional supplements since it affects several enzyme activities and alters inflammatory markers. However, comprehensive preclinical studies and research studies are necessary to lay the groundwork for assessing myricetin's possible effectiveness in treating these long-term ailments. This review summarizes both in vivo and in vitro studies investigating myricetin's possible interactions through the nuclear factor-E2-related factor 2 (Nrf2) as well as PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B) signaling pathways in an attempt to clarify the compound's possible clinical applicability across a range of disorders.

Onion Polyphenols as Multi-Target-Directed Ligands in MASLD: A Preliminary Molecular Docking Study

A sedentary lifestyle associated with unregulated diets rich in high-calorie foods have contributed to the great prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) latterly, with up to 60% in the high-risk population and 25% in the general population. The absence of specific pharmacological strategies for this syndrome represents one of the major problems in the management of MASLD patients. Lifestyle interventions and adherence to a healthy diet are the main cornerstones of current therapies. The identification of nutraceuticals useful in the treatment of MASLD appears to be one of the most promising strategies for the development of new effective and safe treatments for this disease. The onion, one of the most widely studied foods in the field of nutraceuticals, serves as an inexhaustible reservoir of potent compounds with various beneficial effects. The following preliminary study analyzes, mediating in silico studies, the iteration of a library of typical onion compounds with 3-hydroxy-3-methylglutaryl-coenzyme A reductase, liver receptors X α and β, as well as peroxisome proliferator-activated receptors α and γ. In this study, for the first time promising smart molecules from the onion that could have a beneficial action in MASLD patients were identified.

Ameliorative effects of Myrtus communis L. extract involving the inhibition of oxidative stress on high fat diet-induced testis damage in rats

The possible protective effects of Myrtus communis L. (MC) extract on a high fat diet (HFD)-induced testicular injury in a rat model were investigated using histological and biochemical methods. Wistar albino rats were divided into three groups: a standard diet control group; a HFD group; and an HFD+MC group. The HFD and HFD+MC groups were fed with a HFD for 16 weeks. MC extract (100 mg/kg) was given orally five days a week to the rats in the HFD+MC group during the last four weeks of the experiment. Leptin, triglyceride, high-density lipoproteins, cholesterol, estrogen, testosterone, LH and FSH were analyzed in blood serum. Sperm parameters were evaluated from the epididymis. Testicular morphology, proliferative, apoptotic and NADPH oxidase-2 (NOX2)-positive cells were evaluated histologically. Testicular oxidative stress parameters were analyzed biochemically. In the HFD group, lipid and hormone profiles were changed, abnormal spermatozoa, degenerated seminiferous tubules with apoptotic and NOX2-positive cells were increased in number, and sperm motility and germinal proliferative cells decreased compared to the control group. Moreover, testicular malondialdehyde, 8-hydroxy-2-deoxyguanosine and myeloperoxidase levels increased, whereas glutathione and superoxide dismutase levels decreased in the HFD group compared to the control group. All these histological and biochemical features were ameliorated by MC treatment of HFD-fed rats. In conclusion, HFD caused alterations in sperm parameters and testicular morphology by increasing oxidative damage and apoptosis. MC extract may have potential protective effects by inhibiting oxidative damage.

Myricetin Protects Against Rat Intervertebral Disc Degeneration Partly Through the Nrf2/HO-1/NF-κB Signaling Pathway

Intervertebral disc (IVD) degeneration (IDD) is a prevalent musculoskeletal disorder. Nucleus pulposus cells (NPCs) play a significant role in the normal functioning of the IVD. Myricetin is an agent that exerts anti-inflammatory and antioxidant effects in various pathological conditions. Here, we investigated the ameliorative effects of myricetin on the IVD degeneration. NPCs were obtained from the IVD of rats, and were treated with myricetin (0, 5, 10, 15, 20 μM) for 24 h before 20 ng/mL IL-1β stimulation. RT-qPCR, western blotting, and ELISA were applied to evaluate the levels of inflammatory factors (iNOS, COX-2, TNF-α, IL-6, PGE2, and Nitrite) and extracellular matrix (ECM)-associated components (MMP13, ADAMTS-5, aggrecan, and collagen II) in NPCs. Activation status of related signaling pathways (NF-κB and Nrf2) was determined using western blotting and immunofluorescence staining. Experimental rat models of IDD were established using a needle puncture method. Myricetin (20 mg/kg) was administrated intraperitoneally, and the degeneration was evaluated using histopathological analysis. Myricetin treatment attenuated the IL-1β-induced production of inflammatory factors in NPCs. Downregulation of aggrecan and collagen II as well as upregulation of MMP-13 and ADAMTS-5 in NPCs caused by IL-1β was reversed by myricetin treatment. Mechanistically, myricetin blocked NF-κB signaling by activation of Nrf2 in IL-1β-stimulated NPCs. Moreover, inhibition of Nrf2 reversed the protective effects of myricetin in NPCs. The in vivo experiments showed that myricetin ameliorated the IDD progression in rats. The present work suggests that Nrf2 is involved in the pathogenesis of IDD and shows the protective effects as well as the underlying mechanism of myricetin on Nrf2 activation in NPCs.

Research Progress of Natural Products with the Activity of Anti-nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH), a multi-target disease, is becoming a global epidemic. Although several anti-NASH drug candidates are being evaluated in late-stage clinical trials, none have been approved by the FDA to date. Given the global prevalence of the disease, the lack of effective drugs, and the very limited therapeutic efficacy of most of the existing synthetic drugs focusing on a single target, there is an urgent need to continue to develop new therapeutic agents. In contrast, many natural products, including pure compounds and crude extracts, possess hepatoprotective activities. Usually, these natural components are characterized by multi-targeting and low side effects. Therefore, natural products are important resources for the development of new anti- NASH drugs. In this paper, we focus on reviewing the anti-NASH potential, structure, and some of the side effects of natural products based on structural classification. We hope this mini-review will help researchers design and develop new anti-NASH drugs, especially based on the structure of natural products.

Mechanism of Action and Related Natural Regulators of Nrf2 in Nonalcoholic Fatty Liver Disease

With the acceleration of people's pace of life, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world, which greatly threatens people's health and safety. Therefore, there is still an urgent need for higher-quality research and treatment in this area. Nuclear factor Red-2-related factor 2 (Nrf2), as a key transcription factor in the regulation of oxidative stress, plays an important role in inducing the body's antioxidant response. Although there are no approved drugs targeting Nrf2 to treat NAFLD so far, it is still of great significance to target Nrf2 to alleviate NAFLD. In recent years, studies have reported that many natural products treat NAFLD by acting on Nrf2 or Nrf2 pathways. This article reviews the role of Nrf2 in the pathogenesis of NAFLD and summarizes the currently reported natural products targeting Nrf2 or Nrf2 pathway for the treatment of NAFLD, which provides new ideas for the development of new NAFLD-related drugs.

Didymin alleviates metabolic dysfunction-associated fatty liver disease (MAFLD) via the stimulation of Sirt1-mediated lipophagy and mitochondrial biogenesis

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) is one of the most prevalent metabolic syndromes worldwide. However, no approved pharmacological treatments are available for MAFLD. Chenpi, one kind of dried peel of citrus fruits, has traditionally been utilized as a medicinal herb for liver diseases. Didymin is a newly identified oral bioactive dietary flavonoid glycoside derived from Chenpi. In this study, we investigated the therapeutic potential of Didymin as an anti-MAFLD drug and elucidated its underlying mechanisms.

METHODS

High-fat diet (HFD)-induced MAFLD mice and alpha mouse liver 12 (AML12) cells were utilized to evaluate the effects and mechanisms of Didymin in the treatment of MAFLD. Liver weight, serum biochemical parameters, and liver morphology were examined to demonstrate the therapeutic efficacy of Didymin in MAFLD treatment. RNA-seq analysis was performed to identify potential pathways that could be affected by Didymin. The impact of Didymin on Sirt1 was corroborated through western blot, molecular docking analysis, microscale thermophoresis (MST), and deacetylase activity assay. Then, a Sirt1 inhibitor (EX-527) was utilized to confirm that Didymin alleviates MAFLD via Sirt1. Western blot and additional assays were used to investigate the underlying mechanisms.

RESULTS

Our results suggested that Didymin may possess therapeutic potential against MAFLD in vitro and in vivo. By promoting Sirt1 expression as well as directly binding to and activating Sirt1, Didymin triggers downstream pathways that enhance mitochondrial biogenesis and function while reducing apoptosis and enhancing lipophagy.

CONCLUSIONS

These suggest that Didymin could be a promising medication for MAFLD treatment. Furthermore, its therapeutic effects are mediated by Sirt1.

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.

Bamboo leaf: A review of traditional medicinal property, phytochemistry, pharmacology, and purification technology

ETHNOPHARMACOLOGICAL RELEVANCE

Bamboos are perennial evergreen plants that belong to the subfamily Bambusoideae of the true grass family Poaceae, with more than thousands of species distributed around the world. They are used as a traditional medicine with demonstrated effects of anti-oxidation, free radical scavenging, anti-inflammatory, liver protection and ameliorating cognitive deficits. Bamboo leaf is mainly used for the treatment of atherosclerotic, diabetic and nervous system diseases.

AIM OF THE STUDY

This review aims to provide up-to-date information on the traditional medicinal properties, phytochemistry, pharmacology, and purification technologies of bamboo leaf.

MATERIALS AND METHODS

Relevant information on bamboo leaf was obtained by an online search of worldwide accepted scientific databases (Web of Science, ScienceDirect, Elsevier, SpringerLink, ACS Publications, Wiley Online Library and CNKI).

RESULTS

More than 100 chemical compounds, including flavonoids and flavonoid glycosides, volatile components, phenolic acids, polysaccharide, coenzyme Q10, phenylpropanoid and amino acids have been reported to be present. These compounds were usually extracted by column chromatography and membrane separation technologies. Preparative high performance liquid chromatography (PHPLC), high-speed counter-current chromatography (HSCCC), simulated moving bed chromatography (SMB) and dynamic axial compression chromatography (DAC) were the advanced separation technologies have been used to isolate C-glycosides from bamboo leaf flavonoid, the main bioactive ingredient of bamboo leaf. Currently, bamboo leaf is mainly used for the treatment of atherosclerotic, diabetic, hepatic diseases and nervous system related symptoms, which are attributed to the presence of bioactive components of bamboo leaf.

CONCLUSIONS

Phytochemical and pharmacological analyses of bamboo leaf have been revealed in recent studies. However, most of the pharmacological studies on bamboo leaf have focused on bamboo leaf flavonoids. Further studies need to pay more attention to other phytochemical components of bamboo leaf. In addition, there is lack of sufficient clinical data and toxicity studies on bamboo leaf. Therefore, more clinical and toxicity researches on this plant and constituents are recommended.

Thymus linearis Extracts Ameliorate Indices of Metabolic Syndrome in Sprague Dawley Rats

MATERIALS AND METHODS

The extract library (n-hexane (NH), ethyl acetate (EA), methanol (M), distilled water (DW), and combined extract (CE)) was standardized using in vitro phytochemical, antioxidant, and α-amylase inhibition assays, after which the protective effect of selected "hit," i.e., CE against metabolic syndrome, was determined in vivo, using rats fed a high-fat diet supplemented with additional cholesterol administration. CE was administered to Sprague Dawley rats in high dose as 100 mg/kg in carboxymethyl cellulose (CMC) (1 ml; 0.75% in DW) and low-dose group as 50 mg/kg in CMC (0.5 ml; 0.75% in DW). After 10 weeks, the effects of CE on insulin resistance, lipid metabolism, nonalcoholic fatty liver disease (NAFLD), oxidative stress, and genotoxicity were assessed through histological, biochemical, and hematological investigations.

RESULTS

Phytochemical analysis including RP-HPLC analysis of the extracts showed that flavonoids and phenolics (myricetin, kaempferol, and apigenin), previously known to be effective against obesity and diabetes, are present in the extracts. Antioxidant studies revealed that the plant possesses a highly significant (p < 0.05) concentration of antioxidants. Satisfactory α-amylase inhibitory activity was also observed in in vitro experiments. In vivo studies showed that CE-administered animals had significantly (p < 0.05) lower weight gain and smaller adipocytes than the control group. Moreover, CE resisted any significant (p < 0.05) change in the organ weights. Analogous to findings from its traditional use, the plant extract had a positive modulatory effect on insulin resistance and hyperglycemia. The study also indicated that CE resisted high-fat diet-induced disturbance in lipid profile and countered any pathological changes in liver enzymes caused by fat-infused diet. Furthermore, a study on endogenous antioxidant levels indicated that CE was effective in maintaining catalase and peroxidase levels within the normal range and resisted the effects of lipid peroxidation of thiobarbituric acid reactive substances.

CONCLUSION

In principle, the current study's findings scientifically validate the implication of T. linearis in metabolic syndrome and recommend further studies on molecular insights of the observed therapeutic activity.

Nonalcoholic steatohepatitis and mechanisms by which it is ameliorated by activation of the CNC-bZIP transcription factor Nrf2

Non-alcoholic steatohepatitis (NASH) represents a global health concern. It is characterised by fatty liver, hepatocyte cell death and inflammation, which are associated with lipotoxicity, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, iron overload and oxidative stress. NF-E2 p45-related factor 2 (Nrf2) is a transcription factor that combats oxidative stress. Remarkably, Nrf2 is downregulated during the development of NASH, which probably accelerates disease, whereas in pre-clinical studies the upregulation of Nrf2 inhibits NASH. We now review the scientific literature that proposes Nrf2 downregulation during NASH involves its increased ubiquitylation and proteasomal degradation, mediated by Kelch-like ECH-associated protein 1 (Keap1) and/or β-transducin repeat-containing protein (β-TrCP) and/or HMG-CoA reductase degradation protein 1 (Hrd1, also called synoviolin (SYVN1)). Additionally, downregulation of Nrf2-mediated transcription during NASH may involve diminished recruitment of coactivators by Nrf2, due to increased levels of activating transcription factor 3 (ATF3) and nuclear factor-kappaB (NF-κB) p65, or competition for promoter binding due to upregulation of BTB and CNC homology 1 (Bach1). Many processes that downregulate Nrf2 are triggered by transforming growth factor-beta (TGF-β), with oxidative stress amplifying its signalling. Oxidative stress may also increase suppression of Nrf2 by β-TrCP through facilitating formation of the DSGIS-containing phosphodegron in Nrf2 by glycogen synthase kinase-3. In animal models, knockout of Nrf2 increases susceptibility to NASH, while pharmacological activation of Nrf2 by inducing agents that target Keap1 inhibits development of NASH. These inducing agents probably counter Nrf2 downregulation affected by β-TrCP, Hrd1/SYVN1, ATF3, NF-κB p65 and Bach1, by suppressing oxidative stress. Activation of Nrf2 is also likely to inhibit NASH by ameliorating lipotoxicity, inflammation, ER stress and iron overload. Crucially, pharmacological activation of Nrf2 in mice in which NASH has already been established supresses liver steatosis and inflammation. There is therefore compelling evidence that pharmacological activation of Nrf2 provides a comprehensive multipronged strategy to treat NASH.

Deciphering the Effective Constituents and Mechanisms of Portulaca oleracea L. for Treating NASH via Integrating Bioinformatics Analysis and Experimental Pharmacology

Nonalcoholic steatohepatitis (NASH) is a highly prevalent metabolic disorder. Currently, there are no effective pharmacotherapeutic options for preventing and treating NASH. Portulaca oleracea L. (POL) is an edible herb that has been used for preventing and treating some metabolic disorders in China, but the bioactive constituents in POL and the related mechanisms for treating NASH are still unclear. Here, a comprehensive research strategy was used to identify the core genes and the key constituents in POL for treating NASH, via integrating bioinformatics analysis and experimental pharmacology both in vitro and in vivo. The phenotypes and mechanisms of POL were carefully investigated by performing a set of in vivo and in vitro experiments. Bioinformatics analysis suggested that prostaglandin-endoperoxide synthase 2 (PTGS2) was the core target and myricetin (Myr) was the key constituent in POL for treating NASH. In NASH mice model induced by methionine choline deficiency diet, POL significantly alleviated hepatic steatosis and liver injury. In free fatty acids-induced hepatocytes, POL and Myr significantly down-regulated the expression of PTGS2, decreased the number of lipid droplets, and regulated the mRNA expression of lipid synthesis and homeostasis genes, including FASN, CPT1a, SERBP1c, ACC1, and SCD1. In lipopolysaccharide-induced macrophages, POL and Myr significantly reduced the expression of PTGS2 and blocked the secretion of inflammatory mediators TNF-α, IL-6, and IL-1β. Further investigations demonstrate that Myr acts as both suppressor and inhibitor of PTGS2. Collectively, POL and its major component Myr can ameliorate NASH via down-regulating and inhibiting PTGS2, suggesting that POL and Myr can be developed as novel medicines for treating NASH.

Study of the metabolism of myricetin in rat urine, plasma and feces by ultra-high-performance liquid chromatography

Myricetin is a common natural flavonoid compound with various pharmacological activities. However, the metabolite characterization of this substance remains inadequate. In this study, a simple and rapid system strategy based on UHPLC-Q-Exactive Orbitrap mass spectrometry combining parallel reaction monitoring mode was established to screen and identify myricetin metabolites in rat urine, plasma and feces after oral administration. A total of 38 metabolites were fully or partially characterized based on their accurate mass, characteristic fragment ions, retention times, corresponding cLogP values, etc. These metabolites were presumed to be generated through glucuronidation, glucosylation, sulfation, dihydroxylation, acetylation, hydrogenation, hydroxylation and their composite reactions. In addition, the characteristic fragmentation pathways of flavonoids with more metabolites were summarized for the subsequent metabolite identification. The study provides an overall metabolic profile of myricetin, which would be of great help in predicting the in vivo pharmacokinetic profiles and understanding the action mechanism of this active ingredient.

Ameliorative Effect of Myricetin on Nonalcoholic Fatty Liver Disease in ob/ob Mice

Obesity, insulin resistance, and oxidative stress are important risk factors for nonalcoholic fatty liver disease (NAFLD). This study aimed at determining the beneficial effects of myricetin against NAFLD in ob/ob mice. C57BL/6-Lep^ob/ob mice (n = 21) were fed an AIN-93G diet (ob/ob control group) or diet containing 0.04% (low myricetin; LMTN group) or 0.08% (high myricetin; HMTN group) myricetin, and lean heterozygous littermates (lean control group, n = 7) were fed AIN-93G diet for 10 weeks. HMTN consumption significantly lowered serum glucose levels and homeostasis model assessment for insulin resistance values in ob/ob mice. In addition to reducing serum triglyceride (TG) and cholesterol levels, HMTN significantly decreased total hepatic lipid and TG levels partly through downregulation of carbohydrate response element-binding protein and sterol regulatory element-binding protein 1c expression. The reduction in the levels of hepatic thiobarbituric acid reactive substances by HMTN likely resulted from the elevation of nuclear factor erythroid-2-related factor 2 expression. Tumor necrosis factor-α and monocyte chemoattractant protein 1 expressions were reduced by LMTN and HMTN, and HMTN also decreased interleukin-6 expression. These results suggest that myricetin has beneficial effects against NAFLD by regulating the expression of transcription factors of hepatic lipid metabolism, the antioxidant system, and pro-inflammatory cytokines.

Myricetin: A comprehensive review on its biological potentials

Myricetin is a critical nutritive component of diet providing immunological protection and beneficial for maintaining good health. It is found in fruits, vegetables, tea, and wine. The families Myricaceae, Polygonaceae, Primulaceae, Pinaceae, and Anacardiaceae are the richest sources of myricetin. Different researchers explored the therapeutic potential of this valuable constituent such as anticancer, antidiabetic, antiobesity, cardiovascular protection, osteoporosis protection, anti-inflammatory, and hepatoprotective. In addition to these, the compound has been tested for cancer and diabetic mellitus during clinical trials. Health benefits of myricetin are related to its impact on different cell processes, such as apoptosis, glycolysis, cell cycle, energy balance, lipid level, serum protein concentrations, and osteoclastogenesis. This review explored the potential health benefits of myricetin with a specific emphasis on its mechanism of action, considering the most updated and novel findings in the field.

Myricetin improves metabolic outcomes but not cognitive deficit associated to metabolic syndrome in male mice

Myricetin is a flavonol highly prevalent in edible vegetables and fruits, with recognized hypoglycemic and anti-obesity effects, besides great antioxidant capacity. Thus, this study sought to investigate whether myricetin is able to improve metabolic and behavioral outcomes found in monosodium l-glutamate (MSG) obese mice, a model of metabolic syndrome characterized by early hyperinsulinemia associated to obesity, dyslipidemia, hepatic steatosis, anxiety and cognitive deficit. Newborn male mice received MSG (4 mg kg-1 day-1, s.c.) on alternate days during the first 10 days of life for obesity induction, while control pups received equimolar saline solution. From postnatal day 90 to 135, MSG mice were orally treated with myricetin (50 mg kg-1 day-1) or distilled water, while control animals received vehicle. During the last week of treatment, all groups were submitted to behavioral tests: open field maze, elevated plus maze and Morris water maze. At the end of treatment, animals were euthanized for collection of liver, serum and adipose tissue fat pads. Myricetin treatment reduced the elevated serum levels of glucose and triglycerides, typically found in MSG mice, as well as restored peripheral insulin sensitivity and liver steatosis. Moreover, myricetin ameliorated the lack of thigmotaxis and exploratory behavior, but did not improve the cognitive deficit presented by MSG mice. Therefore, this study contributes to the pharmacological validation of myricetin as an affordable and healthy therapeutic adjuvant for the treatment of metabolic syndrome and most of its comorbidities.

Hesperetin ameliorates hepatic oxidative stress and inflammation via the PI3K/AKT-Nrf2-ARE pathway in oleic acid-induced HepG2 cells and a rat model of high-fat diet-induced NAFLD

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disease. Dietary supplementation has become a promising strategy for managing NAFLD. Hesperetin, a citrus flavonoid, is mainly found in citrus fruits (oranges, grapefruit, and lemons) and possesses multiple pharmacological properties, including anti-cancer, anti-Alzheimer and anti-diabetic effects. However, the anti-NAFLD effect and mechanisms of hesperetin remain unclear. In this study, we investigated the therapeutic effect of hesperetin against NAFLD and the underlying mechanism in vitro and in vivo. In oleic acid (OA)-induced HepG2 cells, hesperetin upregulated antioxidant levels (SOD/GPx/GR/GCLC/HO-1) by triggering the PI3 K/AKT-Nrf2 pathway, alleviating OA-induced reactive oxygen species (ROS) overproduction and hepatotoxicity. Furthermore, hesperetin suppressed NF-κB activation and reduced inflammatory cytokine secretion (TNF-α and IL-6). More importantly, we revealed that this anti-inflammatory effect is attributed to reduced ROS overproduction by the Nrf2 pathway, as pre-treatment with Nrf2 siRNA or an inhibitor of superoxide dismutase (SOD) or/and glutathione peroxidase (GPx) abolished hesperetin-induced NF-κB inactivation and reductions in inflammatory cytokine secretion. In a rat model of high-fat diet (HFD)-induced NAFLD, we confirmed that hesperetin relieved hepatic steatosis, oxidative stress, inflammatory cell infiltration and fibrosis. Moreover, hesperetin activated the PI3 K/AKT-Nrf2 pathway in the liver, increasing antioxidant expression and inhibiting NF-κB activation and inflammatory cytokine secretion. In summary, our results demonstrate that hesperetin ameliorates hepatic oxidative stress through the PI3 K/AKT-Nrf2 pathway and that this antioxidative effect further suppresses NF-κB-mediated inflammation during NAFLD progression. Thus, our study suggests that hesperetin may be an effective dietary supplement for improving NAFLD by suppressing hepatic oxidative stress and inflammation.

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.

Current innovations in nutraceuticals and functional foods for intervention of non-alcoholic fatty liver disease

As innovations in global agricultural production and food trading systems lead to major dietary shifts, high morbidity rates from non-alcoholic fatty liver disease (NAFLD), accompanied by elevated risk of lipid metabolism-related complications, has emerged as a growing problem worldwide. Treatment and prevention of NAFLD and chronic liver disease depends on the availability of safe, effective, and diverse therapeutic agents, the development of which is urgently needed. Supported by a growing body of evidence, considerable attention is now focused on interventional approaches that combines nutraceuticals and functional foods. In this review, we summarize the pathological progression of NAFLD and discuss the beneficial effects of nutraceuticals and the active ingredients in functional foods. We also describe the underlying mechanisms of these compounds in the intervention of NAFLD, including their effects on regulation of lipid homeostasis, activation of signaling pathways, and their role in gut microbial community dynamics and the gut-liver axis. In order to identify novel targets for treatment of lipid metabolism-related diseases, this work broadly explores the molecular mechanism linking nutraceuticals and functional foods, host physiology, and gut microbiota. Additionally, the limitations in existing knowledge and promising research areas for development of active interventions and treatments against NAFLD are discussed.

Pathogenesis of NASH and Promising Natural Products

Nonalcoholic steatohepatitis (NASH) is a common clinical condition that can lead to advanced liver diseases. The mechanism of the diaease progression, which is lacking effective therapy, remains obsure. Therefore, there is a need to understand the pathogenic mechanisms responsible for disease development and progression in order to develop innovative therapies. To accomplish this goal, experimental animal models that recapitulate the human disease are necessary. Currently, an increasing number of studies have focused on natural constituents from medicinal plants which have been emerged as a new hope for NASH. This review summarized the pathogenesis of NASH, animal models commonly used, and the promising targets for therapeutics. We also reviewed the natural constituents as potential NASH therapeutic agents.

Amelioration of high-fat diet-induced obesity and its associated complications by a myricetin derivative-rich fraction from Syzygium malaccense in C57BL/6J mice

Obesity is a driving factor in the onset of metabolic disorders. This study aims to investigate the effects of the myricetin derivative-rich fraction (MD) from Syzygium malaccense leaf extract on high-fat diet (HFD)-induced obesity and its associated complications and its influence on uncoupling protein-1 (UCP-1) and gut microbiota in C57BL/6J mice. Mice were randomly assigned into four groups (n = 6) and given a normal diet (ND) or high-fat diet (HFD) for 10 weeks to induce obesity. The HFD groups (continued with HFD) were administered 50 mg kg-1 MD (treatment), 50 mg kg-1 metformin (positive control) and normal saline (HFD and ND controls) daily for four weeks via oral gavage. The ten-week HFD-feeding resulted in hyperglycemia and elevated urinary oxidative indices. The subsequent MD administration caused significant weight reduction without appetite suppression and amelioration of insulin resistance, steatosis and dyslipidemia. Besides, MD significantly reduced lipid hydroperoxides and protein carbonyls in tissue homogenates and urine and elevated Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and reduced glutathione (GSH) and thus, alleviated oxidative stress. The weight reduction was correlated with downregulation of inflammatory markers and the increased UCP-1 level, suggesting weight loss plausibly through thermogenesis. The Akkermansia genus (reflects improved metabolic status) in the HFD50 group was more abundant than that in the HFD group while the non-enzymatic antioxidant markers were strongly associated with UCP-1. In conclusion, MD ameliorates obesity and its related complications possibly via the upregulation of UCP-1 and increased abundance of Akkermansia genus and is promising as a therapeutic agent in the treatment of obesity and its associated metabolic disorders.

Myricetin: A review of the most recent research

Myricetin(MYR) is a flavonoid compound widely found in many natural plants including bayberry. So far, MYR has been proven to have multiple biological functions and it is a natural compound with promising research and development prospects. This review comprehensively retrieved and collected the latest pharmacological abstracts on MYR, and discussed the potential molecular mechanisms of its effects. The results of our review indicated that MYR has a therapeutic effect on many diseases, including tumors of different types, inflammatory diseases, atherosclerosis, thrombosis, cerebral ischemia, diabetes, Alzheimer's disease and pathogenic microbial infections. Furthermore, it regulates the expression of Hippo, MAPK, GSK-3β, PI3K/AKT/mTOR, STAT3, TLR, IκB/NF-κB, Nrf2/HO-1, ACE, eNOS / NO, AChE and BrdU/NeuN. MYR also enhances the immunomodulatory functions, suppresses cytokine storms, improves cardiac dysfunction, possesses an antiviral potential, can be used as an adjuvant treatment against cancer, cardiovascular injury and nervous system diseases, and it may be a potential drug against COVID-19 and other viral infections. Generally, this article provides a theoretical basis for the clinical application of MYR and a reference for its further use.

Nutraceutical Properties of Polyphenols against Liver Diseases

Current food tendencies, suboptimal dietary habits and a sedentary lifestyle are spreading metabolic disorders worldwide. Consequently, the prevalence of liver pathologies is increasing, as it is the main metabolic organ in the body. Chronic liver diseases, with non-alcoholic fatty liver disease (NAFLD) as the main cause, have an alarming prevalence of around 25% worldwide. Otherwise, the consumption of certain drugs leads to an acute liver failure (ALF), with drug-induced liver injury (DILI) as its main cause, or alcoholic liver disease (ALD). Although programs carried out by authorities are focused on improving dietary habits and lifestyle, the long-term compliance of the patient makes them difficult to follow. Thus, the supplementation with certain substances may represent a more easy-to-follow approach for patients. In this context, the consumption of polyphenol-rich food represents an attractive alternative as these compounds have been characterized to be effective in ameliorating liver pathologies. Despite of their structural diversity, certain similar characteristics allow to classify polyphenols in 5 groups: stilbenes, flavonoids, phenolic acids, lignans and curcuminoids. Herein, we have identified the most relevant compounds in each group and characterized their main sources. By this, authorities should encourage the consumption of polyphenol-rich products, as most of them are available in quotidian life, which might reduce the socioeconomical burden of liver diseases.

The Protective Effects of Myricetin against Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death globally, except Africa, and poses a severe health burden worldwide. Both in vitro and in vivo studies have demonstrated the protective effects of myricetin for preventing CVD. For this review, we have assessed the literature from 2009 to 2019 at home and abroad to uncover the protective roles of myricetin for preventing CVD. Myricetin exhibits cardioprotective, anti-hypertensive, anti-atherosclerotic, anti-hyperglycemic, and anti-hyperlipidemic effects. In addition, myricetin may alleviate some of the complications caused by adult-onset diabetes. The combined functions of myricetin allow for the prevention of CVD. This review describes the possible therapeutic benefits of myricetin, along with its potential mechanisms of action, to support the clinical use of the myricetin for the prevention of CVD.

Campomanesia sp. flour attenuates non-alcoholic fatty liver disease on rats fed with a hypercaloric diet

Non-alcoholic fatty liver disease (NAFLD) is a metabolic disorder caused by excess consumption of hypercaloric foods. Guavira (Campomanesia sp.) pulp has broad technological applicability, yet the peel and seeds are considered industrial residue. The objective of this unprecedented study was to evaluate the effects of the flour from guavira's industrial residue (GF) consumption in rats fed with hypercaloric diet (HD). During 65 days, 50 rats were separated into a control group: 1%, 2%, 4% and 8% HD with GF complementation in the diet. The GF chemical composition, phenolic compounds, antioxidant capacity, serum biochemical parameters (glucose, cholesterol, HDL, non-HDL, triglycerides, AST, ALT, and oral glucose tolerance test), fat liver content, and hepatic histomorphology had been characterized. GF is mainly composed of fibres, with phenolic content of 7,391.09 mg AGE/100 g GF and relevant antioxidant capacity (IC50 2.22 and ORAC 155.68 μmol/TE g^-1 ). Serum biochemical analysis did not differ statistically (except ALT reduction, p < .05). Fat liver content was smaller on HD2%GF (p < .0001). The control group and 1% GF showed greater diffuse microvesicular steatosis compared to the other groups when using hepatic morphological analysis (p < .05). GF consumption attenuated NAFLD caused by a hypercaloric diet, and this effect may be related to the fibre content and bioactive compounds in GF.

Myricetin Modulates Macrophage Polarization and Mitigates Liver Inflammation and Fibrosis in a Murine Model of Nonalcoholic Steatohepatitis

This study aimed to investigate the beneficial effects of myricetin in a diet-induced nonalcoholic steatohepatitis (NASH) model and the underlying mechanism. C57BL/6J mice were fed a standard chow or the choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) for 8 weeks with the treatment of myricetin (100 mg/kg) or vehicle by daily gavage. Hepatic inflammation, steatosis, fibrosis, and hepatic stellate cells (HSC) activation were assessed. We also analyzed M1 and M2 macrophages and its related markers in livers from NASH mice and in RAW264.7 macrophages stimulated by lipopolysaccharide (LPS) or interleukin 4 (IL-4) in vitro. Furthermore, we determined the effect of myricetin on the triggering receptor expressed on myeloid cells-1 (TREM-1), toll like receptor (TLR) 2 and 4, and myeloid differentiation factor 88 (MyD88) signaling both in livers from mice and in RAW264.7 cells stimulated by LPS. Our results revealed that myricetin remarkably ameliorated hepatic steatosis, inflammation, and inhibited hepatic macrophage infiltration in CDAHFD-fed mice. Myricetin-treated to CDAHFD-fed mice also inhibited liver fibrosis and HSC activation when compared with vehicle-treated to those mice. Moreover, myricetin inhibited M1 macrophage polarization and its relative markers in livers of NASH mice while induced M2 polarization. Similarly, in vitro study, myricetin inhibited the LPS-induced mRNA expression of M1 macrophages marker genes and induced IL-4-induced M2 macrophage marker genes in RAW264.7 macrophages. Mechanically, myricetin inhibited the expression of TREM-1 and TLR2/4-MyD88 signaling molecules in livers from NASH mice and in RAW264.7 macrophages stimulated by LPS in vitro. Additionally, myricetin inhibited the activation of nuclear factor (NF)-κB signaling and the phosphorylation of the signal transducer and activation of transcription 3 (STAT3) in LPS-stimulated RAW264.7 macrophages. Taken together, our data indicated that myricetin modulated the polarization of macrophages via inhibiting the TREM-1-TLR2/4-MyD88 signaling molecules in macrophages and therefore mitigated NASH and hepatic fibrosis in the CDAHFD-diet-induced NASH model in mice.

Downregulation of PHGDH expression and hepatic serine level contribute to the development of fatty liver disease

OBJECTIVE

Supplementation with serine attenuates alcoholic fatty liver by regulating homocysteine metabolism and lipogenesis. However, little is known about serine metabolism in fatty liver disease (FLD). We aimed to investigate the changes in serine biosynthetic pathways in humans and animal models of fatty liver and their contribution to the development of FLD.

METHODS

High-fat diet (HFD)-induced steatosis and methionine-choline-deficient diet-induced steatohepatitis animal models were employed. Human serum samples were obtained from patients with FLD whose proton density fat fraction was estimated by magnetic resonance imaging. 3-Phosphoglycerate dehydrogenase (Phgdh)-knockout mouse embryonic fibroblasts (MEF) and transgenic mice overexpressing Phgdh (Tg-phgdh) were used to evaluate the role of serine metabolism in the development of FLD.

RESULTS

Expression of Phgdh was markedly reduced in the animal models. There were significant negative correlations of the serum serine with the liver fat fraction, serum alanine transaminase, and triglyceride levels among patients with FLD. Increased lipid accumulation and reduced NAD⁺ and SIRT1 activity were observed in Phgdh-knockout MEF and primary hepatocytes incubated with free fatty acids; these effects were reversed by overexpression of Phgdh. Tg-Phgdh mice showed significantly reduced hepatic triglyceride accumulation compared with wild-type littermates fed a HFD, which was accompanied by increased SIRT1 activity and reduced expression of lipogenic genes and proteins.

CONCLUSIONS

Human and experimental data suggest that reduced Phgdh expression and serine levels are closely associated with the development of FLD.

Myricetin alleviated hepatic steatosis by acting on microRNA-146b/thyroid hormone receptor b pathway in high-fat diet fed C57BL/6J mice

Hepatic microRNAs (miRs) regulate local thyroid hormone (TH) action and TH-related lipid metabolism. We previously found that myricetin effectively ameliorated hepatic steatosis by targeting PPAR signaling pathway, in which the differentially expressed genes were TH-responsive. The present study was designed to explore the mechanism by which myricetin regulated miR-dependent TH action and lipid metabolism on high-fat diet (HFD)-induced hepatic steatosis. C57BL/6J mice were fed a HFD with or without 100 mg kg-1 myricetin by oral gavage for 16 weeks (n = 8 for each group). The results showed that myricetin improved HFD-induced hepatic steatosis, increased serum TH levels and hepatic type 1 deiodinase (DIO1) activities, and elevated energy expenditure in relation to the HFD mice. Meanwhile, myricetin inhibited miR-205 and miR-146b up-regulation induced by HFD, and also up-regulated their targets, Dio1 and thyroid hormone receptor b (TRb) expression, at both the transcriptional and translational levels, accompanied by the regulation of TH responsive lipid metabolism genes. Overexpression or knockdown of miR-205 failed to affect Dio1 mRNA and protein levels in primary mouse hepatocytes. Myricetin directly decreased miR-146b expression in miR-146b mimic-treated hepatocytes to elevate TRb levels. However, the beneficial effects of myricetin on hepatic TH action and lipid metabolism were abolished by TRb siRNA in free fatty acid (FFA)-treated hepatocytes. Our results indicated that myricetin attenuated hepatic steatosis via the miR-146b/TRb pathway and should be considered for the management of NAFLD conditions.

Activation of Nrf2/HO-1 signal with Myricetin for attenuating ECM degradation in human chondrocytes and ameliorating the murine osteoarthritis

BACKGROUND

Osteoarthritis (OA), one of the prevailing joint degenerative disorders, contributes to the disability around the world. However, no effective therapeutic was introduced currently. Myricetin was reported to possess the function of anti-inflammatory, anti-diabetic and anti-cancer. Thus, we investigate the protection role of myricetin in OA progression and the potential molecular mechanism in present study.

METHODS

Quantitative realtime PCR and western blotting were performed to evaluate the expression of MMP-13, Aggrecan, iNOS, and COX-2 at both gene and protein levels. An enzyme-linked immunosorbent assay was used to evaluate the levels of inflammatory factors (PGE2, TNF-α, and IL-6). The PI3K/AKT, Nrf2/HO-1 and nuclear factor kappa B (NF-κB) signaling pathways were analyzed by western blotting, and immunofluorescence was used to assess the expression of Nrf2, Collagen II and MMP13. The in vitro effect of myricetin was evaluated by intragastric administration into a mouse osteoarthritis model induced by destabilization of the medial meniscus.

RESULTS

Myricetin not only inhibited the generation of inflammatory mediators and cytokines such as nitric oxide (NO), prostaglandin E2 (PGE2), TNF-α and IL-6, but also suppressed the production of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in human chondrocytes under IL-1β stimulation. Moreover, Metalloproteinase 13 (MMP13) and thrombospondin motifs 5 (ADAMTS5), which resulted in the degradation of cartilage, were also suppressed in chondrocytes with the treatment of myricetin. To explore the potential mechanism, we found out that myricetin suppressed NF-κB signaling pathway through Nrf2/HO-1 axis in human chondrocytes. Besides, myricetin regulated the Nrf2 signaling pathway through PI3K/Akt pathway. In addition, in vivo study demonstrated that myricetin could ameliorated the progression of OA in mice DMM model through PI3K/Akt mediated Nrf2 signaling pathway.

CONCLUSION

Taken together, our data first demonstrated that myricetin possesses the therapeutic potential on OA through PI3K/Akt mediated Nrf2/HO-1 signaling pathway.

Myricetin Ameliorates Ethanol-Induced Lipid Accumulation in Liver Cells by Reducing Fatty Acid Biosynthesis

SCOPE

Alcoholic liver disease is a serious threat to human health. The development of drug candidates from complementary and alternative medicines is an attractive approach. Myricetin can be found in fruit, vegetables, and herbs. This study investigates the protective effect of myricetin on ethanol-induced injury in mouse liver cells.

METHODS AND RESULTS

Oil-red O staining, assays of oxidative stress and measurements of inflammatory markers in mouse AML12 liver cells collectively demonstrate that myricetin elicits a curative effect on ethanol-induced injury. Next, the role of myricetin in the metabolic regulation of ethanol pathology in liver cells is assessed by gas chromatography coupled with mass spectrometry. Myricetin inhibits ethanol-stimulated fatty acid biosynthesis. Additionally, dodecanoic acid may be proposed as a potential biomarker related to ethanol pathology or myricetin therapy. It is also observed that myricetin enhances ethanol-induced inhibition of the mitochondrial electron transport chain. Moreover, fumaric acid is found to be a candidate biomarker related to ethanol toxicity or myricetin therapy. Quantitative reverse-transcription-PCR shows that ethanol-induced fatty acid synthase and sterol regulatory element-binding protein-1c mRNA levels are alleviated by myricetin. Finally, myricetin increases ethanol-induced inhibition of phosphorylation of AMP-activated protein kinase.

CONCLUSION

These results elucidate the pharmacological mechanism of myricetin on ethanol-induced lipid accumulation.

Myricetin Attenuated Diabetes-Associated Kidney Injuries and Dysfunction via Regulating Nuclear Factor (Erythroid Derived 2)-Like 2 and Nuclear Factor-κB Signaling

Background/Aims: Previous studies have suggested that myricetin (Myr) could promote the expression and nuclear translocation of nuclear factor (erythroid-derived 2)-like (Nrf2). This study aimed to investigate whether Myr could attenuate diabetes-associated kidney injuries and dysfunction in wild-type (WT) and Nrf2 knockdown (Nrf2-KD) mice.

Methods: Lentivirus-mediated Nrf2-KD and WT mice were used to establish type 1 diabetes mellitus (DM) by streptozotocin (STZ) injection. WT and Nrf2-KD mice were then randomly allocated into four groups: control (CON), Myr, STZ, and STZ + Myr. Myr (100 mg/kg/day) or vehicle was administered for 6 months. Kidneys were harvested and weighed at the end of the experiment. Hematoxylin and eosin staining and Masson’s trichrome staining were used to assess the morphology and fibrosis of the kidneys, respectively. Urinary albumin-to-creatinine ratio was used to test renal function. Western blotting was performed to determine oxidative-stress- or inflammation-associated signaling pathways. Real-time polymerase chain reaction (RT-PCR) was performed to detect the expression of fibrosis or inflammatory cytokines at the message Ribonucleic Acid (mRNA) level.

Results: In WT mice, Myr alleviated DM-induced renal dysfunction, fibrosis, and oxidative damage and enhanced the expression of Nrf2 and its downstream genes. After knockdown of Nrf2, Myr treatment partially but significantly mitigated DM-induced renal dysfunction and fibrosis, which might be associated with inhibition of the I-kappa-B (IκB)/nuclear factor-κB (NF-κB) (P65) signaling pathway.

Conclusions: This study showed that Myr prevented DM-associated decreased expression of Nrf2 and inhibited IκB/NF-κB (P65) signaling pathway. Moreover, inhibition of IκB/NF-κB (P65) signaling pathway is independent of the regulation of Nrf2. Thus, Myr could be a potential treatment for preventing the development and progression of DM-associated kidney injuries and dysfunction.

Pistachio Consumption Prevents and Improves Lipid Dysmetabolism by Reducing the Lipid Metabolizing Gene Expression in Diet-Induced Obese Mice

Pistachios contain beneficial substances such as unsaturated fatty acids, phytosterols, and polyphenols. In the present study, we investigated if pistachio consumption is able to prevent or to revert hyperglycemia, dyslipidemia, hepatic steatosis, and adipose tissue morphological alterations caused by high fat diet (HFD) in the mouse. Moreover, the impact of pistachio intake on the mRNA expression of peroxisome proliferator-activated receptor γ (PPAR-γ), fatty acid transport proteins (FAT-P), fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD1), and sterol regulatory element-binding transcription factor-1c (SREBP-1c) in liver and adipose tissue was also analyzed. No change in body weight, food intake, and hyperglycemia was observed between mice consuming pistachios (HFD-P) and HFD mice. Pistachio intake was able to prevent but not to reverse HFD-induced hypertriglyceridemia. Cholesterol plasma levels, steatosis grading, body fat mass, and adipocyte size were significantly lower in HFD-P group compared to HFD in both prevention and reversal protocol. Pistachio-diet was able to prevent HFD-induced overexpression of PPAR-γ, FAS, and SCD1 in the liver and SREBP-1c, PPAR-γ, and FAT-P in adipose tissue. Similarly, HFD-P significantly ameliorated the expression levels of FAT-P and SCD1 in the liver and SREBP-1c, FAS, and SCD1 in adipose tissue of obese mice. The present study shows that pistachio consumption is able to prevent and to ameliorate obesity-related dysfunctions by positively modulating the expression of genes linked to lipid metabolism.

Postgenomic Properties of Natural Micronutrients

Modern medical approaches to the therapy of various diseases, including cancer, are based on the use of toxic drugs. The unfavorable side effects of traditional medicine could be counterbalanced by addition of natural bioactive substances to conventional therapy due to their mild action on cells combined with the multitargeted effects. To elucidate the real mechanisms of their biological activity, versatile approaches including a number of "omics" such as genomics, transcriptomics, proteomics, and metabolomics are used. This review highlights inclusion of bioactive natural compounds into the therapy of chronic diseases from the viewpoint of modern omics-based nutritional biochemistry. The recently accumulated data argue for necessity to employ nutrigenetic and nutrimetabolomic analyses to prevent or diminish the risk of chronic diseases.

Niga-ichigoside F1 ameliorates high-fat diet-induced hepatic steatosis in male mice by Nrf2 activation

Niga-ichigoside F1 ameliorated high-fat diet-induced hepatic steatosis by increasing Nrf2 nuclear translocation to regulate lipid metabolism genes expression in livers of C57BL/6J mice.