Scutellarin ameliorates nonalcoholic fatty liver disease through the PPARγ/PGC-1α-Nrf2 pathway

Bioprotective Role of Phytocompounds Against the Pathogenesis of Non-alcoholic Fatty Liver Disease to Non-alcoholic Steatohepatitis: Unravelling Underlying Molecular Mechanisms

Non-alcoholic fatty liver disease (NAFLD), with a global prevalence of 25%, continues to escalate, creating noteworthy concerns towards the global health burden. NAFLD causes triglycerides and free fatty acids to build up in the liver. The excessive fat build-up causes inflammation and damages the healthy hepatocytes, leading to non-alcoholic steatohepatitis (NASH). Dietary habits, obesity, insulin resistance, type 2 diabetes, and dyslipidemia influence NAFLD progression. The disease burden is complicated due to the paucity of therapeutic interventions. Obeticholic acid is the only approved therapeutic agent for NAFLD. With more scientific enterprise being directed towards the understanding of the underlying mechanisms of NAFLD, novel targets like lipid synthase, farnesoid X receptor signalling, peroxisome proliferator-activated receptors associated with inflammatory signalling, and hepatocellular injury have played a crucial role in the progression of NAFLD to NASH. Phytocompounds have shown promising results in modulating hepatic lipid metabolism and de novo lipogenesis, suggesting their possible role in managing NAFLD. This review discusses the ameliorative role of different classes of phytochemicals with molecular mechanisms in different cell lines and established animal models. These compounds may lead to the development of novel therapeutic strategies for NAFLD progression to NASH. This review also deliberates on phytomolecules undergoing clinical trials for effective management of NAFLD.

Protective effects of scutellaria-coptis herb couple against non-alcoholic steatohepatitis via activating NRF2 and FXR pathways in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria-coptis herb couple (SC) is a classic herbal pair used in many Traditional Chinese Medicine (TCM) formulations in the treatment of endocrine and metabolic deseases. Diabetes mellitus and non-alcoholic steatohepatitis (NASH) are both endocrine and metabolic diseases. Previous studies have shown that SC has anti-diabetic effects. However, the effect and mechanism of SC against NASH remains unclear.

AIM OF THE STUDY

This study aimed to demonstrate the effect and mechanism of SC against NASH through the nuclear factor-erythroid 2-related factor 2 (Nrf2) and farnesoid X receptor (FXR) dual signaling pathways in vivo and in vitro.

MATERIALS AND METHODS

The high fat diet-fed rat model, and HepG2 and RAW264.7 cell models were used. Serum biochemical indexes and liver histopathological changes were examined. Metabolomics, transcriptomics, and flow cytometry were performed. RT-qPCR and western blot analysis were performed to provide expression of NRF2 and FXR pathway signal molecules during SC's anti-NASH treatment in vivo and in vitro.

RESULTS

SC had anti-NASH effects in vivo with significantly improvement of serum NASH biochemical index and hepatopathological structure; meanwhile, SC significantly elevated the expression levels of FXR protein in liver and intestinal tissues, and cholesterol 7a-hydroxylase (CYP7A1) protein in liver. The mRNA expression levels of Takeda G protein receptor 5 (TGR5), CYP7A1, fibroblast growth factor receptor-4 (FGFR4), FXR, small heterodimer partner (SHP), fibroblast growth factor 15/19 (FGF15/19) and glucagon-like peptide-1 (GLP-1) were significantly elevated by SC. SC reduced the levels of NorCA, isoLCA and α-MCA in the feces of NAFLD rats. In vitro, SC-containing serum (SC-CS) was found to significantly reduce intracellular lipid deposition, inhibit ROS production, reduce intracellular Malondialdehyde (MDA) and IL-1β levels, and enhance the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Six differential genes closely related to oxidative stress and Nrf2 were identified by transcriptomic analysis. SC-CS up-regulated the expression of NRF2, and reduced the expression of TXNIP and Caspase-1 genes in RAW264.7 cells. In addition, SC-CS reduced the expression of Keap1 and NF-κB, and up-regulated the expression of Nrf2, heme oxygenase-1 (HO-1), quinone oxidoreductase 1 (NQO1), and SOD; SC-CS elevated the protein level of NRF2, and reduced the protein level of TXNIP in HepG2 cells.

CONCLUSIONS

the mechanisms of SC action against NASH was closely related to the simultaneous activations of both NRF2 and FXR signaling pathways. These findings provide a new insight into the anti-NASH application of SC in clinical settings and demonstrate the potential of SC in the treatment of NASH.

Aerobic exercise-induced decrease of chemerin improved glucose and lipid metabolism and fatty liver of diabetes mice through key metabolism enzymes and proteins

Our previous studies have implicated an important role of adipokine chemerin in exercise-induced improvements of glycolipid metabolism and fatty liver in diabetes rat, but the underlying mechanisms remain unknown. This study first used an exogenous chemerin supplement to clarify the roles of decreased chemerin in exercised diabetes mice and possible mechanisms of glucose and lipid metabolism key enzymes and proteins [such as adipose triglyceride lipase (ATGL), lipoprotein lipase (LPL), phosphoenolpyruvate carboxykinase (PEPCK), and glucose transporter 4 (GLUT4)]. In addition, two kinds of adipose-specific chemerin knockout mice were generated to demonstrate the regulation of chemerin on glucose and lipid metabolism enzymes and proteins. We found that in diabetes mice, exercise-induced improvements of glucose and lipid metabolism and fatty liver, and exercise-induced increases of ATGL, LPL, and GLUT4 in liver, gastrocnemius and fat were reversed by exogenous chemerin. Furthermore, in chemerin knockdown mice, chemerin(-/-)∙adiponectin mice had lower body fat mass, improved blood glucose and lipid, and no fatty liver; while chemerin(-/-)∙fabp4 mice had hyperlipemia and unchanged body fat mass. Peroxisome proliferator-activated receptor γ (PPARγ), ATGL, LPL, GLUT4 and PEPCK in the liver and gastrocnemius had improve changes in chemerin(-/-)·adiponectin mice while deteriorated alterations in chemerin(-/-)·fabp4 mice, although PPARγ, ATGL, LPL, and GLUT4 increased in the fat of two kinds of chemerin(-/-) mice. CONCLUSIONS: Decreased chemerin exerts an important role in exercise-induced improvements of glucose and lipid metabolism and fatty liver in diabetes mice, which was likely to be through PPARγ mediating elevations of ATGL, LPL and GLUT4 in peripheral metabolic organs.

Saponins of Tomato Extract Improve Non-Alcoholic Fatty Liver Disease by Regulating Oxidative Stress and Lipid Homeostasis

The present study investigated the impact of saponins of tomato extract (STE) on non-alcoholic fatty liver disease (NAFLD). The findings demonstrated that introducing STE in NAFLD mice revealed promising results in ameliorating symptoms of oxidative stress, lipid metabolism disorders, visceral fat deposition and fatty liver disease. Moreover, the mechanistic studies have demonstrated that STE delivers its effects by activating adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), thereby suppressing downstream protein expression associated with fatty acid synthesis. In such conditions, lipid metabolism can be improved. Simultaneously, STE enhanced nuclear factor erythroid 2-related factor 2 (Nrf2) and entry into the nucleus and initiated the transcription of downstream antioxidant factors, thereby relieving oxidative stress induced by a high-fat diet and lowering oxidative damage to the liver. Such results imply that the administration of STE can be regarded as a viable treatment option for NAFLD, providing a mechanism that can regulate the AMPK and Nrf2 signaling pathways.

Natural products in non-alcoholic fatty liver disease (NAFLD): Novel lead discovery for drug development

With changing lifestyles, non-alcoholic fatty liver disease (NAFLD) has become the most prevalent liver disease worldwide. A substantial increase in the incidence, mortality, and associated burden of NAFLD-related advanced liver disease is expected. Currently, the initial diagnosis of NAFLD is still based on ultrasound and there is no approved treatment method. Lipid-lowering drugs, vitamin supplementation, and lifestyle improvement treatments are commonly used in clinical practice. However, most lipid-lowering drugs can produce poor patient compliance and specific adverse effects. Therefore, the exploration of bio-diagnostic markers and active lead compounds for the development of innovative drugs is urgently needed. More and more studies have reported the anti-NAFLD effects and mechanisms of natural products (NPs), which have become an important source for new drug development to treat NAFLD due to their high activity and low side effects. At present, berberine and silymarin have been approved by the US FDA to enter clinical phase IV studies, demonstrating the potential of NPs against NAFLD. Studies have found that the regulation of lipid metabolism, insulin resistance, oxidative stress, and inflammation-related pathways may play important roles in the process. With the continuous updating of technical means and scientific theories, in-depth research on the targets and mechanisms of NPs against NAFLD can provide new possibilities to find bio-diagnostic markers and innovative drugs. As we know, FXR agonists, PPARα agonists, and dual CCR2/5 inhibitors are gradually coming on stage for the treatment of NAFLD. Whether NPs can exert anti-NAFLD effects by regulating these targets or some unknown targets remains to be further studied. Therefore, the study reviewed the potential anti-NAFLD NPs and their targets. Some works on the discovery of new targets and the docking of active lead compounds were also discussed. It is hoped that this review can provide some reference values for the development of non-invasive diagnostic markers and new drugs against NAFLD in the clinic.

Mefenamic Acid-Upregulated Nrf2/SQSTM1 Protects Hepatocytes against Oxidative Stress-Induced Cell Damage

Mefenamic acid (MFA) is a commonly prescribed non-steroidal anti-inflammatory drug (NSAID) with anti-inflammatory and analgesic properties. MFA is known to have potent antioxidant properties and a neuroprotective effect against oxidative stress. However, its impact on the liver is unclear. This study aimed to elucidate the antioxidative effects of MFA and their underlying mechanisms. We observed that MFA treatment upregulated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Treatment with various anthranilic acid derivative-class NSAIDs, including MFA, increased the expression of sequestosome 1 (SQSTM1) in HepG2 cells. MFA disrupted the interaction between Kelch-like ECH-associated protein 1 (Keap1) and Nrf2, activating the Nrf2 signaling pathway. SQTM1 knockdown experiments revealed that the effect of MFA on the Nrf2 pathway was masked in the absence of SQSTM1. To assess the cytoprotective effect of MFA, we employed tert-Butyl hydroperoxide (tBHP) as a ROS inducer. Notably, MFA exhibited a protective effect against tBHP-induced cytotoxicity in HepG2 cells. This cytoprotective effect was abolished when SQSTM1 was knocked down, suggesting the involvement of SQSTM1 in mediating the protective effect of MFA against tBHP-induced toxicity. In conclusion, this study demonstrated that MFA exhibits cytoprotective effects by upregulating SQSTM1 and activating the Nrf2 pathway. These findings improve our understanding of the pharmacological actions of MFA and highlight its potential as a therapeutic agent for oxidative stress-related conditions.

Scutellarin prevents acute alcohol-induced liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and inhibiting inflammation by regulating the AKT, p38 MAPK/NF-κB pathways

Alcoholic liver disease (ALD) is the most frequent liver disease worldwide, resulting in severe harm to personal health and posing a serious burden to public health. Based on the reported antioxidant and anti-inflammatory capacities of scutellarin (SCU), this study investigated its protective role in male BALB/c mice with acute alcoholic liver injury after oral administration (10, 25, and 50 mg/kg). The results indicated that SCU could lessen serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and improve the histopathological changes in acute alcoholic liver; it reduced alcohol-induced malondialdehyde (MDA) content and increased glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD) activity. Furthermore, SCU decreased tumor necrosis factor-‍α (TNF-‍α), interleukin-6 (IL-6), and IL-‍1β messenger RNA (mRNA) expression levels, weakened inducible nitric oxide synthase (iNOS) activity, and inhibited nucleotide-binding oligomerization domain (NOD)‍-like receptor protein 3 (NLRP3) inflammasome activation. Mechanistically, SCU suppressed cytochrome P450 family 2 subfamily E member 1 (CYP2E1) upregulation triggered by alcohol, increased the expression of oxidative stress-related nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) pathways, and suppressed the inflammation-related degradation of inhibitor of nuclear factor-‍κB (NF-‍κB)‍-‍α (IκBα) as well as activation of NF‍-‍κB by mediating the protein kinase B (AKT) and p38 mitogen-activated protein kinase (MAPK) pathways. These findings demonstrate that SCU protects against acute alcoholic liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and suppressing inflammation by regulating the AKT, p38 MAPK/NF-κB pathways.

Nuclear factor erythroid 2-related factor 2-mediated signaling and metabolic associated fatty liver disease

Oxidative stress is a key driver in the development and progression of several diseases, including metabolic associated fatty liver disease (MAFLD). This condition includes a wide spectrum of pathological injuries, extending from simple steatosis to inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. Excessive buildup of lipids in the liver is strictly related to oxidative stress in MAFLD, progressing to liver fibrosis and cirrhosis. The nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of redox homeostasis. NRF2 plays an important role for cellular protection by inducing the expression of genes related to antioxidant, anti-inflammatory, and cytoprotective response. Consistent evidence demonstrates that NRF2 is involved in every step of MAFLD deve-lopment, from simple steatosis to inflammation, advanced fibrosis, and ini-tiation/progression of hepatocellular carcinoma. NRF2 activators regulate lipid metabolism and oxidative stress alleviating the fatty liver disease by inducing the expression of cytoprotective genes. Thus, modulating NRF2 activation is crucial not only in understanding specific mechanisms underlying MAFLD progression but also to characterize effective therapeutic strategies. This review outlined the current knowledge on the effects of NRF2 pathway, modulators, and mechanisms involved in the therapeutic implications of liver steatosis, inflammation, and fibrosis in MAFLD.

Non-Alcoholic Fatty Liver Disease (NAFLD) Pathogenesis and Natural Products for Prevention and Treatment

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease, affecting approximately one-quarter of the global population, and has become a world public health issue. NAFLD is a clinicopathological syndrome characterized by hepatic steatosis, excluding ethanol and other definite liver damage factors. Recent studies have shown that the development of NAFLD is associated with lipid accumulation, oxidative stress, endoplasmic reticulum stress, and lipotoxicity. A range of natural products have been reported as regulators of NAFLD in vivo and in vitro. This paper reviews the pathogenesis of NAFLD and some natural products that have been shown to have therapeutic effects on NAFLD. Our work shows that natural products can be a potential therapeutic option for NAFLD.

Natural flavonoids: Potential therapeutic strategies for non-alcoholic fatty liver disease

The incidence of non-alcoholic fatty liver disease (NAFLD) is increasing rapidly worldwide; however, there are currently limited treatments for NAFLD. The disease spectrum includes simple fatty liver, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and progression to hepatocellular carcinoma (NASH-HCC). The therapeutic effects of NAFLD remain controversial. Although researchers have conducted studies on the pathogenesis of NAFLD, its pathogenesis and anti-NAFLD mechanisms have not been fully elucidated. Previous studies have found that flavonoids, as natural substances with extensive pharmacological activity and good therapeutic effects, have excellent antioxidant, anti-inflammatory, metabolic disease improvement, anti-tumor, and other properties and can significantly alleviate NAFLD. Flavonoids could be further developed as therapeutic drugs for NAFLD. In this paper, the pathogenesis of NAFLD and the mechanisms of flavonoids against NAFLD are summarized to provide a theoretical basis for screening flavonoids against non-alcoholic liver injury.

New compounds with hepatoprotective effects from the stems of Sabia parviflora

Three new compounds, (8S)-2,2,7,7-tetramethyl-8-hydroxymethyl-6H-indanone-(2,3-b)-2H-pyran-9-O-β-d-glucopyranoside (1), (7S,8S)-2,2,7-trimethyl-7-hydroxymethyl-8-hydroxy-2,7,8,9-tetrahydro-6H-naphtho-(2,3-b)-pyran-10-O-β-d-glucopyranoside (2), 1-deoxy-1-(3,4-dihydro-7-methyl-2,3-dioxo-1(2H)-quinoxalinyl)pentitol-6-carboxylic acid (3), as well as six known compounds (4-9), were obtained. Their structures were determined by spectroscopy and comparison with NMR data of related compounds. Absolute configurations were determined by ECD spectroscopy. The hepatoprotective effects of these compounds were investigated on HepG2 and LO2 cells lines; compounds 1, 2, and 4 displayed moderate activity.

Chemoprotective Effect of Scutellarin against Gastric Cancer in Rats: An in vitro and in vivo Study

This study evaluated the chemoprotective effect of scutellarin (SC) in vitro and in vivo against gastric carcinogenesis in rats and celllines and examined the underlying mechanism. Gastric cancer celllines (AGS) was used for the in vitro study and lactate dehydrogenase (LDH) profile, histone deacetylase (HDAC) assay, cell cycle & apoptosis ratio and antioxidant parameters were measured. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was used to induce gastric carcinogenesis in rats and the rats received the different doses of SC (10, 20 and 30 mg/kg). The body weight and tumor incidence were measured at regular time intervals. The antioxidant and pro-inflammatory cytokines were estimated. The finding of data showed that the drug was effective against AGS cell line. Supplementation of scutellarin revealed an upregulation in body weight compared with the MNNG group rats. Moreover, it also reduced the incidence of tumor. It also altered the significant DNA density, LDH content, mucus content and acidity. Scutellarin treated rats showed improved activity in enzymatic and non-enzymatic antioxidant profile and reversed the content of cytokines compared with MNNG induced gastric cancer group rats. This research reveals the chemoprotective property of the scutellarin and highlights the promising role of drug by alteration of inflammatory pathway by minimizing its adverse effect.

Breviscapine alleviates NASH by inhibiting TGF-β-activated kinase 1-dependent signaling

BACKGROUND AND AIMS

NAFLD is a key component of metabolic syndrome, ranging from nonalcoholic fatty liver to NASH, and is now becoming the leading cause of cirrhosis and HCC worldwide. However, due to the complex and unclear pathophysiological mechanism, there are no specific approved agents for treating NASH. Breviscapine, a natural flavonoid prescription drug isolated from the traditional Chinese herb Erigeron breviscapus, exhibits a wide range of pharmacological properties, including effects on metabolism. However, the anti-NASH efficacy and mechanisms of breviscapine have not yet been characterized.

APPROACH AND RESULTS

We evaluated the effects of breviscapine on the development of hepatic steatosis, inflammation, and fibrosis in vivo and in vitro under metabolic stress. Breviscapine treatment significantly reduced lipid accumulation, inflammatory cell infiltration, liver injury, and fibrosis in mice fed a high-fat diet, a high-fat/high-cholesterol diet, or a methionine- and choline-deficient diet. In addition, breviscapine attenuated lipid accumulation, inflammation, and lipotoxicity in hepatocytes undergoing metabolic stress. RNA-sequencing and multiomics analyses further indicated that the key mechanism linking the anti-NASH effects of breviscapine was inhibition of TGF-β-activated kinase 1 (TAK1) phosphorylation and the subsequent mitogen-activated protein kinase signaling cascade. Treatment with the TAK1 inhibitor 5Z-7-oxozeaenol abrogated breviscapine-mediated hepatoprotection under metabolic stress. Molecular docking illustrated that breviscapine directly bound to TAK1.

CONCLUSION

Breviscapine prevents metabolic stress-induced NASH progression through direct inhibition of TAK1 signaling. Breviscapine might be a therapeutic candidate for the treatment of NASH.

Natural PPARs agonists for the treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a general term for a series of liver diseases including simple steatosis, non-alcoholic steatohepatitis, liver fibrosis, which is closely related to metabolic syndrome. The pathogenesis of NAFLD is relatively complex, which has gradually changed from the previous 'two-hit' hypothesis to the current "multiple hits" hypothesis. However, there is currently no approved treatment for NAFLD in clinic, highlighting the urgent need for drug development. Peroxisome proliferator activated receptors (PPARs) are members of the nuclear receptor superfamily, whose different subtypes have been proved to regulate different stages of NAFLD, thus becoming promising drug targets for NAFLD. As important sources of drug development, natural products have been proven to treat NAFLD through multiple pathways and multiple targets. In this paper, we outline the regulatory role of PPARs in NAFLD, and summarize some natural products that target PPARs to ameliorate NAFLD, in order to provide reference for drug development of NAFLD.

Scutellarin protects the kidney from ischemia/reperfusion injury by targeting Nrf2

BACKGROUND

Acute kidney injury (AKI) results in high morbidity and mortality among inpatients, while effective treatment and intervention are still absent. Therefore, this study aims to explore the effects of Scutellarin (Scu) in experimental models in vivo and in vitro.

METHODS

In vivo experiment, we employed a total of 30 Wistar rats, which further were modelled by a bilateral renal pedicle clip for 45 min, then received 50 mg/kg/day Scu. In vitro, HK-2 cells were administered with 20μΜ Scu and then incubated in hypoxia/reoxygenation (H/R) conditions for 24 h. The knockdown of Nrf2 expression was conducted by small interfering RNA (siRNA) transfection.

RESULTS

As a result, the AKI model was well established with an increased SCr, BUN, KIM-1 level, and histological injury score, while Scu treatment reduced the levels above and increased the antioxidative enzyme HO-1. H/R induced an increase of ROS in HK-2 cells, while Scu decreased the ROS level. Bioinformatics results showed the transcription factor Nrf2 was a hub protein during the AKI, which also bound to Scu with low binding energy, indicating that the downstream effect of Scu might be mediated by Nrf2. To verify the suppose above, we employed siRNA against Nrf2, which shows a significant increase in ROS after Nrf2 was blocked. Meanwhile, the HO-1 showed similar expression compared with the 'H/R + Nrf2 siRNA' and 'H/R + Nrf2 siRNA + Scu' group, implying the protective effect of Scu was mediated by the Nrf2/HO-1 pathway.

CONCLUSION

Scu led to up-regulation of HO-1 through activating the Nrf2 signalling pathway, protecting the kidneys from ischemia/reperfusion (I/R)-induced oxidative damage.

Dietary phenolic-type Nrf2-activators: implications in the control of toxin-induced hepatic disorders

Numerous studies have exemplified the importance of nuclear factor erythroid 2-related factor 2 (Nrf2) activation in the alleviation of toxin-induced hepatic disorders primarily through eliminating oxidative stress. Whereafter, increasingly more efforts have been contributed to finding Nrf2-activators, especially from dietary polyphenols. The present review summarized the phenolic-type Nrf2-activators published in the past few decades, analyzed their effectiveness based on their structural characteristics and outlined their related mechanisms. It turns out that flavonoids are the largest group of phenolic-type Nrf2-activators, followed by nonflavonoids and phenolic acids. When counting on subgroups, the top three types are flavonols, flavones, and hydroxycinnamic acids, with curcuminoids having the highest effective doses. Moreover, most polyphenols work through the phosphorylation of Nrf2. Besides, mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt) are the frequent targets of these Nrf2-activators, which indirectly mediate the behavior of Nrf2. However, current data are not sufficient to conclude any structure-activity relationship.

Oxidative Stress, Genomic Integrity, and Liver Diseases

Excess reactive oxygen species production and free radical formation can lead to oxidative stress that can damage cells, tissues, and organs. Cellular oxidative stress is defined as the imbalance between ROS production and antioxidants. This imbalance can lead to malfunction or structure modification of major cellular molecules such as lipids, proteins, and DNAs. During oxidative stress conditions, DNA and protein structure modifications can lead to various diseases. Various antioxidant-specific gene expression and signal transduction pathways are activated during oxidative stress to maintain homeostasis and to protect organs from oxidative injury and damage. The liver is more vulnerable to oxidative conditions than other organs. Antioxidants, antioxidant-specific enzymes, and the regulation of the antioxidant responsive element (ARE) genes can act against chronic oxidative stress in the liver. ARE-mediated genes can act as the target site for averting/preventing liver diseases caused by oxidative stress. Identification of these ARE genes as markers will enable the early detection of liver diseases caused by oxidative conditions and help develop new therapeutic interventions. This literature review is focused on antioxidant-specific gene expression upon oxidative stress, the factors responsible for hepatic oxidative stress, liver response to redox signaling, oxidative stress and redox signaling in various liver diseases, and future aspects.

rhEPO Upregulates the PPARγ Pathway in Long-term Cultured Primary Nerve Cells via PI3K/Akt to Delay Cell Senescence

Previous studies have confirmed that both recombinant human erythropoietin (rhEPO) and peroxisome proliferator-activated receptors γ (PPARγ) activator pioglitazone can protect senescent nerve cells, and their mechanisms involve enhancing cell antioxidant capacity and reducing cell apoptosis. However, whether the PPARγ pathway is involved in the rhEPO anti-aging process in neuronal cells is still unclear. In this study, to explore the relationship between rhEPO and the PPARγ pathway at the cellular level, primary nerve cells cultured for 22 days were used to simulate the natural aging process of nerve cells. Starting on the 11th day of culture, rhEPO, LY294002, and GW9662 were added for treatment. Immunochemical methods and SA-β-gal staining were used to observe the changes in cellular antioxidant capacity and the fraction of senescent cells. The results showed that PPARγ blockade retarded the effect of rhEPO on the cellular antioxidant capacity and altered the fraction of senescent cells. It was confirmed that PPARγ was involved in rhEPO's anti-aging process in neuronal cells. Real-time fluorescent quantitative RT-PCR, Western blotting, and immunofluorescence staining were used to observe the changes in PPARγ pathway-related factors in nerve cells after rhEPO treatment. The results showed that rhEPO significantly upregulated the expression of PPARγ coactivator-1α (PGC-1α), PPARγ, and nuclear PPARγ in cells but did not affect the level of phosphorylated PPARγ protein, confirming that rhEPO has the ability to upregulate the PPARγ pathway. PI3K/Akt and PPARγ pathway blockade experiments were used to explore the relationships among rhEPO, PI3K/Akt, and PPARγ. The results showed that after PPARγ blockade, rhEPO had no significant effect on the PI3K/Akt pathway-related factor p-Akt, while after PI3K/Akt blockade, rhEPO's effects on PPARγ-related factors (PGC-1α, PPARγ, and nuclear PPARγ) were significantly decreased. It is suggested that rhEPO delays the PI3K/Akt pathway in the process of neuronal senescence, which is located upstream of PPARγ regulation. In conclusion, this study confirmed that rhEPO can upregulate the expression of PGC-1α and PPARγ in cells and the level of PPARγ protein in the nucleus to enhance the antioxidant capacity of cells and delay the senescence of nerve cells through the PI3K/Akt pathway. These findings will provide ideas for finding new targets for neuroprotection research and will also provide a theoretical basis and experimental evidence for rhEPO anti-aging research in neural cells.

Activation of the PPARγ Prevents Ferroptosis-Induced Neuronal Loss in Response to Intracerebral Hemorrhage Through Synergistic Actions With the Nrf2

Intracerebral hemorrhage (ICH) is a subtype of stroke characterized by high mortality and disability rates. The long-term effects of ICH-induced intracranial hematoma on patients’ neurological function are unclear. Currently, an effective treatment that significantly reduces the rates of death and disability in patients with ICH is not available. Based on accumulating evidence, ferroptosis may be the leading factor contributing to the neurological impairment caused by ICH injury. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated receptor in the nuclear hormone receptor family that synergistically interacts with the nuclear factor erythrocyte 2-related factor 2 (Nrf2) pathway to promote the expression of related genes and inhibit ferroptosis. Primary rat hippocampal neurons were treated with heme (50 μM) and erastin (50 μM) to induce ferroptosis, followed by the PPARγ agonist pioglitazone (PDZ, 10 μM) to verify the inhibitory effect of PPARγ activation on ferroptosis. ML385 (2 μM), a novel and specific NRF2 inhibitor, was administered to the inhibitor group, followed by an analysis of cellular activity and immunofluorescence staining. In vivo Assays, ICH rats injected with autologous striatum were treated with 30 mg/kg/d pioglitazone, and the inhibitor group was injected with ML385 (30 mg/kg). The results showed that PDZ inhibited ferroptosis in neurons by increasing the expression of PPARγ, Nrf2 and Gpx4 in vitro, while PDZ reduced ferroptosis in neurons after ICH and promoted the recovery of neural function in vivo. Our results suggest that PDZ, a PPARγ agonist, promotes Gpx4 expression through the interaction between PPARγ and the Nrf2 pathway, inhibits ferroptosis of neurons after ICH, and promotes the recovery of neural function.

Smart NIR-II croconaine dye-peptide for enhanced photo-sonotheranostics of hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is associated with high morbidity and mortality rates. The development of novel nanomaterials represents an important direction for precise HCC theranostics. The combination of photothermal and sonodynamic therapy has provided great benefits for HCC therapy. Theranostic agents in the second near-infrared window (NIR-II, 1000-1700 nm) show great prospects because of their extraordinarily high detection sensitivity, resolution, and deep penetration. Methods: A sharp pH-sensitive self-assembling Glypican-3 (GPC3)-binding peptide (GBP) dye, CR-PEG-GBP, was developed as an intelligent nanoprobe for NIR-II imaging and photoacoustic (PA) imaging-guided photothermal therapy (PTT) and sonodynamic therapy (SDT) of HCC. Results: This small molecule assembled nanoprobe exhibited advantageous properties, such as responding to a decrease in pH (from normal tissue (pH 7.4) to the tumor microenvironment (pH ~6.5)) and aggregating - from small nanoprobes (<20 nm at pH 7.4) - into large nanoparticles (>160 nm at pH 6.5 and >510 nm at pH 5.5) that enables enhanced imaging and therapeutic effects. Because CR-PEG-GBP can self-aggregate in situ in an acidic tumor microenvironment, it shows high tumor accumulation and long tumor retention time, while being excretable from normal tissues and safe. Conclusions: This intelligent self-assembling small molecule strategy provides a simple yet efficient solution for HCC theranostics and may open up new avenues for designing clinically translatable probes for HCC treatment.

Scutellarin ameliorates hepatic lipid accumulation by enhancing autophagy and suppressing IRE1α/XBP1 pathway

Nonalcoholic fatty liver disease is the most prevalent liver disease characterized by excessive lipid accumulation in hepatocytes. Endoplasmic reticulum (ER) stress and autophagy play an important role in lipid accumulation. In this study, scutellarin (Scu) was examined in palmitic acid-treated HepG2 cells and C57/BL6 mice fed a high-fat diet (HFD). Scu reduced intracellular lipid content and inhibited sterol regulatory element binding protein-1c (SREBP-1c)-mediated lipid synthesis and fatty acid translocase-mediated lipid uptake in HepG2 cells. Additionally, Scu restored impaired autophagy and inhibited excessive activation of ER stress in vivo and in vitro. Moreover, Scu upregulated forkhead box O transcription factor 1-mediated autophagy by inhibiting inositol-requiring enzyme 1α (IRE1α)/X-box-binding protein 1 (XBP1) branch activation, while XBP1s overexpression exacerbated the lipid accumulation and impaired autophagy in HepG2 cells and also weakened the positive effects of Scu. Furthermore, Scu attenuated ER stress by activating autophagy, ultimately downregulating SREBP-1c-mediated lipid synthesis, and autophagy inhibitors offset these beneficial effects. Scu inhibited the crosstalk between autophagy and ER stress and downregulated saturated fatty acid-induced lipid accumulation in hepatocytes. These findings demonstrate that Scu ameliorates hepatic lipid accumulation by enhancing autophagy and suppressing ER stress via the IRE1α/XBP1 pathway.

Advances in Chemical Constituents, Clinical Applications, Pharmacology, Pharmacokinetics and Toxicology of Erigeron breviscapus

Dengzhanxixin (DZXX), the dried whole plant of Erigeron breviscapus (Vaniot) Hand.-Mazz., belonging to Compositae and first published in Materia Medica of South Yunnan by Lan Mao in the Ming Dynasty (1368 AD–1644 AD), is included in Medicinal Materials and Decoction Pieces of the 2020 edition of the Pharmacopeia of the People’s Republic of China. Its main chemical components are flavonoids that mainly include flavonoid, flavonols, dihydroflavones, flavonol glycosides, flavonoid glycosides, coffee acyl compounds, and other substances, such as volatile oil compounds, coumarins, aromatic acids, pentacyclic terpenoids, phytosterols, and xanthones. Among them, scutellarin and 1,5-dicoffeoylquininic acid are the main active components of DZXX. DZXX has pharmacological effects, such as improving cerebral and cerebrovascular ischemia, increasing blood flow, inhibiting platelet aggregation, promoting antithrombotic formation, improving microcirculation, reducing blood viscosity, protecting optic nerves, exhibiting anti-inflammatory properties, scavenging free radicals, and eliciting antioxidant activities. It is widely used in the treatment of cardiovascular and cerebrovascular ischemic diseases, kidney diseases, liver diseases, diabetic complications, and glaucoma. Pharmacokinetic studies have shown that the active components of DZXX have a low bioavailability and a high elimination rate in vivo. Nevertheless, its utilization can be improved through liposome preparation and combination with other drugs. Acute and subacute toxicity studies have shown that DZXX is a safe medicinal material widely used in clinical settings. However, its target and drug action mechanism are unclear because of the complexity of its composition. In this paper, the clinical application and pharmacological toxicology of DZXX are reviewed to provide a reference for further studying its active components and action mechanism.

Phytochemicals: Targeting Mitophagy to Treat Metabolic Disorders

Metabolic disorders include metabolic syndrome, obesity, type 2 diabetes mellitus, non-alcoholic fatty liver disease and cardiovascular diseases. Due to unhealthy lifestyles such as high-calorie diet, sedentary and physical inactivity, the prevalence of metabolic disorders poses a huge challenge to global human health, which is the leading cause of global human death. Mitochondrion is the major site of adenosine triphosphate synthesis, fatty acid β-oxidation and ROS production. Accumulating evidence suggests that mitochondrial dysfunction-related oxidative stress and inflammation is involved in the development of metabolic disorders. Mitophagy, a catabolic process, selectively degrades damaged or superfluous mitochondria to reverse mitochondrial dysfunction and preserve mitochondrial function. It is considered to be one of the major mechanisms responsible for mitochondrial quality control. Growing evidence shows that mitophagy can prevent and treat metabolic disorders through suppressing mitochondrial dysfunction-induced oxidative stress and inflammation. In the past decade, in order to expand the range of pharmaceutical options, more and more phytochemicals have been proven to have therapeutic effects on metabolic disorders. Many of these phytochemicals have been proved to activate mitophagy to ameliorate metabolic disorders. Given the ongoing epidemic of metabolic disorders, it is of great significance to explore the contribution and underlying mechanisms of mitophagy in metabolic disorders, and to understand the effects and molecular mechanisms of phytochemicals on the treatment of metabolic disorders. Here, we investigate the mechanism of mitochondrial dysfunction in metabolic disorders and discuss the potential of targeting mitophagy with phytochemicals for the treatment of metabolic disorders, with a view to providing a direction for finding phytochemicals that target mitophagy to prevent or treat metabolic disorders.

Breviscapine: A Review on its Phytochemistry, Pharmacokinetics and Therapeutic Effects

Breviscapine is one of the extracts of several flavonoids of Erigeron breviscapus. Scutellarin is the main active component of breviscapine, and the qualitative or quantitative criteria as well. Scutellarin and its analogs share a similar skeleton of the flavonoids. Breviscapine has been widely used in the treatment of cerebral infarction and its sequelae, cerebral thrombus, coronary heart disease (CHD), and angina pectoris. Breviscapine has a broad spectrum of pharmacological activities, such as increasing blood flow, improving microcirculation, dilating blood vessels, decreasing blood viscosity, promoting fibrinolysis, inhibiting platelet aggregation, and thrombosis formation, etc. In addition, breviscapine and its analogs have significant value for drug research and development because of the superiority of those significant bioactivities. Furthermore, an increasing number of pharmacokinetic studies have explored the mechanism of scutellarin and its analogs. To provide a comprehensive understanding of the current research on breviscapine, scutellarin, and the analogs, the structural features, distribution situation, preparation method, content determination method, clinical applications, pharmacological action as well as pharmacokinetics are summarized in the present review.

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.

Rosmarinic acid exerts an antagonistic effect on nonalcoholic fatty liver disease by regulating the YAP1/TAZ-PPARγ/PGC-1α signaling pathway

Rosmarinic acid (RA) is a water-soluble phenolic compound extracted from Boraginaceae and Lamiaceae. This study was designed to investigate the role and mechanism of action of RA in improving nonalcoholic fatty liver disease (NAFLD). Male SD rats maintained on a high fat diet and L02 cells stimulated with oleic acid were treated with RA. Our results showed that RA significantly reduced total cholesterol, triglycerides, low-density lipoprotein cholesterol, alanine aminotransferase, aspartate aminotransferase, and malondialdehyde levels and increased high-density lipoprotein cholesterol, superoxide dismutase and adenosine triphosphate levels both in vivo and in vitro. Hematoxylin and eosin staining and oil red O staining showed that RA had a good lipid-lowering effect and substantial protective effects on liver injury. Transmission electron microscopy and JC-1 fluorescence results showed that RA could improve mitochondrial damage in hepatocytes. Additionally, flow cytometry results indicated that RA inhibited ROS generation and apoptosis in L02 cells. The impaired hepatocytes were restored by using RA in NAFLD models characterized by down-regulating YAP1 and TAZ, meanwhile up-regulating PPARγ and PGC-1α. When YAP1 was over-expressed, RA reduced the expression of YAP1; however, the action of RA was significantly blocked by silencing YAP1. The experimental results indicated that RA markedly alleviated NAFLD by repairing mitochondrial damage and regulating the YAP1/TAZ-PPARγ/PGC-1α signaling pathway.

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.

Scutellarin Inhibits the Growth and EMT of Gastric Cancer Cells through Regulating PTEN/PI3K Pathway

Gastric cancer is one of the most common malignancies with a high mortality rate world. This study intends to make clear the role and mechanism of the Scutellarin (Scu), a flavonoid isolated from Erigeron breviscapus (Vant.) Hand.-Mazz, in regulating the evolvement of gastric cancer. We selected different doses of Scu to treat gastric cancer cells (MGC-803 and AGS). Then, cell counting kit-8 (CCK8) assay was conducted to verify the proliferation of tumor cells, while flow cytometry was adopted to test the apoptosis rate. Meanwhile, Western blot was conducted to examine epithelial-mesenchymal transition (EMT) markers and the expression of phosphatase and tensin homolog (PTEN)/phosphatidylinositol 3-kinase (PI3K) and apoptosis-related proteins (Bax, Bcl2 and Caspase3). Moreover, xenograft tumor experiment in nude mice was established to verify the effect of Scu on tumor growth. Furthermore, the knockdown model of PTEN was constructed, and the influence of PTEN on the anti-tumor effect of Scu was investigated. As a result, Scu inhibited cell proliferation, EMT and promoted the apoptosis in gastric cancer dose-dependently. Additionally, Scu attenuated tumor cell growth in vivo. Besides, Scu enhanced the expression of PTEN while reduced the phosphorylated level of PI3K. Moreover, the mechanistic study proved that Scu inactivated PI3K by up-regulating PTEN, thus dampening tumor progression. In conclusion, Scu dampened the growth and EMT of gastric cancer by regulating the PTEN/PI3K pathway.

Chemical Activators of the Nrf2 Signaling Pathway in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is paralleling the insulin resistance and obesity epidemic and is regarded as liver metabolic syndrome, and its prevalence rate is increasing rapidly. The best explanation for the occurrence and development of NAFLD is the “multiple hit” hypothesis instead of the “two-hit” hypothesis. At present, NAFLD therapies are limited. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway is a key pathway in oxidative stress. Its downstream proteins/enzymes are regulated. Metabolic enzymes and antioxidant proteins/enzymes play a vital role in cell defense protection and have attracted attention in the field of antioxidant research in recent years. This paper summarizes the regulatory mechanism of the Nrf2 signaling pathway and the research progress of Nrf2 activators in NAFLD to provide guidance for NAFLD therapy in the future.

Scutellarin attenuates hypoxia/reoxygenation injury in hepatocytes by inhibiting apoptosis and oxidative stress through regulating Keap1/Nrf2/ARE signaling

Scutellarin is a natural flavonoid that has been found to exhibit anti-ischemic effect. However, the effect of scutellarin on hepatic hypoxia/reoxygenation (ischemia-reperfusion (I/R)) injury remains unknown. The aim of the present study was to explore the protective effect of scutellarin on I/R-induced injury in hepatocytes. Our results showed that scutellarin improved cell viability in hepatocytes exposed to hypoxia/reoxygenation (H/R). Scutellarin treatment resulted in decreased levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and increased superoxide dismutase (SOD) activity in H/R-induced hepatocytes. In addition, scutellarin reduced cell apoptosis in H/R-stimulated hepatocytes, as proved by the decreased apoptotic rate. Moreover, scutellarin significantly up-regulated bcl-2 expression and down-regulated bax expression in hepatocytes exposed to H/R. Furthermore, scutellarin treatment caused significant decrease in Keap1 expression and increase in nuclear Nrf2 expression. Besides, scutellarin induced the mRNA expressions of heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1). Inhibition of Nrf2 significantly reversed the protective effects of scutellarin on H/R-stimulated hepatocytes. In conclusion, these findings demonstrated that scutellarin protected hepatocytes from H/R-induced oxidative injury through regulating the Keap1/Nrf2/ARE signaling pathway, indicating a potential relevance of scutellarin in attenuating hepatic I/R injury.

Metabolic Impact of Flavonoids Consumption in Obesity: From Central to Peripheral

The prevention and treatment of obesity is primary based on the follow-up of a healthy lifestyle, which includes a healthy diet with an important presence of bioactive compounds such as polyphenols. For many years, the health benefits of polyphenols have been attributed to their anti-oxidant capacity as free radical scavengers. More recently it has been described that polyphenols activate other cell-signaling pathways that are not related to ROS production but rather involved in metabolic regulation. In this review, we have summarized the current knowledge in this field by focusing on the metabolic effects of flavonoids. Flavonoids are widely distributed in the plant kingdom where they are used for growing and defensing. They are structurally characterized by two benzene rings and a heterocyclic pyrone ring and based on the oxidation and saturation status of the heterocyclic ring flavonoids are grouped in seven different subclasses. The present work is focused on describing the molecular mechanisms underlying the metabolic impact of flavonoids in obesity and obesity-related diseases. We described the effects of each group of flavonoids in liver, white and brown adipose tissue and central nervous system and the metabolic and signaling pathways involved on them.

Identification of Crucial Genetic Factors, Such as PPARγ, that Regulate the Pathogenesis of Fatty Liver Disease in Dairy Cows Is Imperative for the Sustainable Development of Dairy Industry

Frequently occurring fatty liver disease in dairy cows during the perinatal period, a typical type of non-alcoholic fatty liver disease (NAFLD), results in worldwide high culling rates of dairy cows (averagely about 25%) after calving. This has been developing into a critical industrial problem throughout the world, because the metabolic disease severely affects the welfare and economic value of dairy cows. Findings about the molecular mechanisms how the fatty liver disease develops would help scientists to discover novel therapeutic targets for NAFLD. Studies have shown that PPARγ participates or regulates the fat deposition in liver by affecting the biological processes of hepatic lipid metabolism, insulin resistance, gluconeogenesis, oxidative stress, endoplasmic reticulum stress and inflammation, which all contribute to fatty liver. This review mainly focuses on crucial regulatory mechanisms of PPARγ regulating lipid deposition in the liver via direct and/or indirect pathways, suggesting that PPARγ might be a potential critical therapeutic target for fatty liver disease, however, it would be of our significant interest to reveal the pathology and pathogenesis of NAFLD by using dairy cows with fatty liver as an animal model. This review will provide a molecular mechanism basis for understanding the pathogenesis of NAFLD.

Scutellarin Attenuates the IL-1β-Induced Inflammation in Mouse Chondrocytes and Prevents Osteoarthritic Progression

Osteoarthritis (OA) is a chronic degenerative disease wherein the articular cartilage exhibits inflammation and degradation. Scutellarin (SCU) is a flavonoid glycoside with a range of pharmacological activities, as shown in previous studies demonstrating its anti-inflammatory activity. How SCU impacts the progression of OA, however, has not been explored to date. Herein, we assessed the impact of SCU on murine chondrocytes in an OA model system. In in vitro assays, we measured chondrocyte expression of key OA-associated factors such as matrix metalloproteinase 13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) via qRT-PCR and Western blotting, the expression of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and prostaglandin E2 (PGE2) were detected by qRT-PCR. Our results showed that the downregulation of MMP-13, ADAMTS-5, COX-2, and iNOS expression by SCU and the overproduction of IL-6, TNF-α, and PGE2 induced by IL-1β were all inhibited by SCU in a concentration-dependent manner. Moreover, SCU was able to reverse aggrecan and collagen II degradation and nuclear factor-κB (NF-κB) and nuclear factor erythroid-derived 2-like 2 (Nrf2) signaling pathway activation both in vivo and in vitro. We further used a destabilization of the medial meniscus (DMM) murine model of OA to explore the therapeutic benefits of SCU in vivo. Together, our findings suggest SCU to be a potentially valuable therapeutic agent useful for treating OA.

The Role of PGC-1α and Mitochondrial Biogenesis in Kidney Diseases

Chronic kidney disease (CKD) is one of the fastest growing causes of death worldwide, emphasizing the need to develop novel therapeutic approaches. CKD predisposes to acute kidney injury (AKI) and AKI favors CKD progression. Mitochondrial derangements are common features of both AKI and CKD and mitochondria-targeting therapies are under study as nephroprotective agents. PGC-1α is a master regulator of mitochondrial biogenesis and an attractive therapeutic target. Low PGC-1α levels and decreased transcription of its gene targets have been observed in both preclinical AKI (nephrotoxic, endotoxemia, and ischemia-reperfusion) and in experimental and human CKD, most notably diabetic nephropathy. In mice, PGC-1α deficiency was associated with subclinical CKD and predisposition to AKI while PGC-1α overexpression in tubular cells protected from AKI of diverse causes. Several therapeutic strategies may increase kidney PGC-1α activity and have been successfully tested in animal models. These include AMP-activated protein kinase (AMPK) activators, phosphodiesterase (PDE) inhibitors, and anti-TWEAK antibodies. In conclusion, low PGC-1α activity appears to be a common feature of AKI and CKD and recent characterization of nephroprotective approaches that increase PGC-1α activity may pave the way for nephroprotective strategies potentially effective in both AKI and CKD.

Dietary Platycodon grandiflorus Attenuates Hepatic Insulin Resistance and Oxidative Stress in High-Fat-Diet Induced Non-Alcoholic Fatty Liver Disease

The root of Platycodon grandiflorus (PG), with hepatoprotective and anti-oxidation effects, has a long history of being used as food and herbal medicine in Asia. However, the mechanism of PG against non-alcoholic fatty liver disease (NAFLD) is still not clear. The aim of this study was to investigate the mechanism of PG suppressing the development of NAFLD induced by a high-fat diet (HFD) in mice. Male C57BL/6J mice were fed with either a standard chow diet or a HFD, either supplemented with or without PG, for 16 weeks. Serum lipids, liver steatosis, oxidative stress and insulin sensitivity were determined. Expressions or activities of hepatic enzymes in the related pathways were analyzed to investigate the mechanisms. PG significantly reduced HFD-induced hepatic injury and hyperlipidemia, as well as hepatic steatosis via regulating phosphorylation of acetyl-CoA carboxylase (p-ACC) and expression of fatty acid synthase (FAS). In addition, PG ameliorated oxidative stress by restoring glutathione (GSH) content and antioxidant activities, and improved insulin sensitivity by regulating the PI3K/Akt/GSK3β signaling pathway. Our data showed that dietary PG have profound effects on hepatic insulin sensitivity and oxidative stress, two key factors in the pathogenesis of NAFLD, demonstrating the potential of PG as a therapeutic strategy for NAFLD.

Influence of Olive Extracts on the Expression of Genes Involved in Lipid Metabolism in Medaka Fish

Aims. To assess the possible effect of polyphenol-rich olive extracts on lipid metabolism in medaka fish by quantifying the expression of lipogenic and lipolytic genes. Materials and methods. Adult medaka fish were maintained in tanks for five days with five extracts at 0.01% in water, causing obesity through a diet rich in carbohydrates, with a control group maintained in water with a normal diet. The extracts contained polyphenols ranging between 7 and 116 mg/g (oleuropein, hydroxytyrosol) with an antioxidant power of 2-13 mmol of 2,4,6-tri(2-pyridyl)-1,3,5-triazine/100 g. After five days, the fish were sacrificed and the hepatic mRNA and its complementary DNA were extracted by reverse transcription. Complementary DNAs were quantified for three lipolytic and three lipogenic genes by real-time PCR. The relative gene expression was calculated from the amplification curves in reference to the control group. Results. The expression of genes involved in lipolysis, including peroxisome proliferator-activated receptor-±, acyl-CoA oxidase 1, and carnitine palmitoyltransferase 1, were clearly decreased in fish subjected to an obesogenic diet, and this situation could not be reversed in fish maintained with polyphenol-rich extracts. In contrast, lipogenic fatty acid synthase, acetyl-CoA carboxylase 1, and sterol regulatory element-binding protein 1 genes increased considerably with the obesogenic diet and reverted to the normal state with the olive extracts. The effect was not dependent on the total polyphenol content, the specific oleuropein or hydroxytyrosol concentration, or the antioxidant power, suggesting a synergistic effect. Conclusion. Olive polyphenols, acting as anti-lipogenic agents, have a positive effect on lipid metabolism, but their mechanism in each gene is different according to the extract, which supports synergistic mechanisms with the different proportions of polyphenols and accompanying phytochemicals in each extract.

The Role of Nrf2 in Liver Disease: Novel Molecular Mechanisms and Therapeutic Approaches

Oxidative stress and inflammation are the most important pathogenic events in the development and progression of liver diseases. Nuclear erythroid 2-related factor 2 (Nrf2) is the master regulator of the cellular protection via induction of anti-inflammatory, antioxidant, and cyto-protective genes expression. Multiple studies have shown that activation or suppression of this transcriptional factor significantly affect progression of liver diseases. Comprehensive understanding the roles of Nrf2 activation/expression and the outcomes of its activators/inhibitors are indispensable for defining the mechanisms and therapeutic strategies against liver diseases. In this current review, we discussed recent advances in the function and principal mechanisms by regulating Nrf2 in liver diseases, including acute liver failure, hepatic ischemia-reperfusion injury (IRI), alcoholic liver disease (ALD), viral hepatitis, non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma (HCC).

Grape Leucoanthocyanidin Protects Liver Tissue in Albino Rabbits with Nonalcoholic Hepatic Steatosis

Nonalcoholic fatty liver disease (NAFLD) is a common ailment. It is usually found in association with diabetes or obesity. There are no approved drugs to treat this condition. The study of flavonoid consumption has increased over the decades due to their antioxidative properties, although the literature is scarce when it comes to their effects in liver tissue. The purpose of this study was to evaluate the role of leucoanthocyanidin in nonalcoholic hepatic steatosis. Thirty male albino rabbits were divided in 3 groups. Group 1 had a regular commercial diet. The second group had a regular diet and 10 mL of egg yolk and 1.5 g of pure cholesterol. The rabbits of the third group were on the same regimen as the second, but were also treated with grape leucoanthocyanidin (50 mg/kg/day) for 100 days. On the last day of the experiment, the animals were euthanized, and the livers excised and fixated in a 10% formalin solution. Afterwards, fragments of each liver were removed and histologically processed and analyzed. The stereological evaluation showed that leucoanthocyanidin reduced NAFLD in comparison with the nontreated group. This was also observed in the histological analysis of the liver tissue, as the treated group had less foci of fatty tissue. Leucoanthocyanidin may therefore be a promising substance to treat NAFLD, although further studies are needed.