Dihydromyricetin ameliorates oleic acid-induced lipid accumulation in L02 and HepG2 cells by inhibiting lipogenesis and oxidative stress. Life Sci. 2016;157:131-139. [PMID: 27265384 DOI: 10.1016/j.lfs.2016.06.001]

Exploration of the potential mechanism of aqueous extract of Artemisia capillaris for the treatment of non-alcoholic fatty liver disease based on network pharmacology and experimental verification

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is a nutritional and metabolic disease with a high prevalence today. Artemisia capillaris has anti-inflammatory, antioxidant, and other effects. However, the mechanism of A. capillaris in treating NAFLD is still poorly understood.

METHODS

This study explored the mechanism of A. capillaris in the treatment of NAFLD through network pharmacology and molecular docking, and verified the results through in vivo experiments using a high-fat diet-induced mouse model and in vitro experiments using an oleic acid-induced HepG2 cell model.

KEY FINDINGS

Aqueous extract of A. capillaris (AEAC) can reduce blood lipids, reduce liver lipid accumulation and liver inflammation in NAFLD mice, and improve NAFLD. Network pharmacology analysis revealed that 51 drug ingredients in A. capillaris correspond to 370 targets that act on NAFLD. GEO data mining obtained 93 liver differentially expressed genes related to NAFLD. In the UHPLC-MS detection results, 36 components were characterized and molecular docked with JNK. Verified in vitro and in vivo, the results show that JNK and the phosphorylation levels of IL-6, IL-1β, c-Jun, c-Fos, and CCL2 are key targets and pathways.

CONCLUSIONS

This study confirmed that AEAC reduces lipid accumulation and inflammation in the liver of NAFLD mice by inhibiting the JNK/AP-1 pathway.

9-HODE and 9-HOTrE alter mitochondrial metabolism, increase triglycerides, and perturb fatty acid uptake and synthesis associated gene expression in HepG2 cells

Non-Alcoholic Fatty Liver Disease (NAFLD) prevalence is rising and can lead to detrimental health outcomes such as Non-Alcoholic Steatohepatitis (NASH), cirrhosis, and cancer. Recent studies have indicated that Cytochrome P450 2B6 (CYP2B6) is an anti-obesity CYP in humans and mice. Cyp2b-null mice are diet-induced obese, and human CYP2B6-transgenic (hCYP2B6-Tg) mice reverse the obesity or diabetes progression, but with increased liver triglyceride accumulation in association with an increase of several oxylipins. Notably, 9-hydroxyoctadecadienoic acid (9-HODE) produced from linoleic acid (LA, 18:2, ω-6) is the most prominent of these and 9-hydroxyoctadecatrienoic acid (9-HOTrE) from alpha-linolenic acid (ALA, 18:3, ω-3) is the most preferentially produced when controlling for substrate concentrations in vitro. Transactivation assays indicate that 9-HODE and 9-HOTrE activate PPARα and PPARγ. In Seahorse assays performed in HepG2 cells, 9-HOTrE increased spare respiratory capacity, slightly decreased palmitate metabolism, and increased non-glycolytic acidification in a manner consistent with slightly increased glutamine utilization; however, 9-HODE exhibited no effect on metabolism. Both compounds increased triglyceride and pyruvate concentrations, most strongly by 9-HOTrE, consistent with increased spare respiratory capacity. qPCR analysis revealed several perturbations in fatty acid uptake and metabolism gene expression. 9-HODE increased expression of CD36, FASN, PPARγ, and FoxA2 that are involved in lipid uptake and production. 9-HOTrE decreased ANGPTL4 expression and increased FASN expression consistent with increased fatty acid uptake, fatty acid production, and AMPK activation. Our findings support the hypothesis that 9-HODE and 9-HOTrE promote steatosis, but through different mechanisms as 9-HODE is directly involved in fatty acid uptake and synthesis; 9-HOTrE weakly inhibits mitochondrial fatty acid metabolism while increasing glutamine use.

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.

Metabolomics reveals the effects of Lactiplantibacillus plantarum dy-1 fermentation on the lipid-lowering capacity of barley β-glucans in an in vitro model of gut-liver axis

Bioactive polysaccharides known as the biological response modifiers, can directly interact with intestinal epithelium cells (IEC) and regulate key metabolic processes such as lipid metabolism. Here, the coculture of Caco-2/HT29 monolayer (>400 Ω × cm2) and HepG2 cells was developed to mimic the gut-liver interactions. This system was used to investigate the effects of raw and fermented barley β-glucans (RBG and FBG) on lipid metabolism by directly interacting with IEC. Both RBG and FBG significantly and consistently reduced the lipid droplets and triacylglycerol levels in monoculture and coculture of HepG2 overloaded with oleic acid. Notably, FBG significantly and distinctly elevated PPARα (p < 0.05) and PPARα-responsive ACOX-1 (p < 0.01) gene expressions, promoting lipid degradation in cocultured HepG2. Moreover, the metabolomics analyses revealed that FBG had a unique impact on extracellular metabolites, among them, the differential metabolite thiomorpholine 3-carboxylate was significantly and strongly correlated with PPARα (r = -0.68, p < 0.01) and ACOX-1 (r = -0.76, p < 0.01) expression levels. Taken together, our findings suggest that FBG-mediated gut-liver interactions play a key role in its lipid-lowering effects that are superior to those of RBG. These results support the application of Lactiplantibacillus fermentation for improving hypolipidemic outcomes.

A comprehensive review of vine tea: Origin, research on Materia Medica, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Vine tea is a popular folk tea that has been consumed in China for more than 1200 years. It is often used in ethnic medicine by ethnic groups in southwest China with at least 35 aliases in 10 provinces. In coastal areas, vine tea is mostly used to treat heatstroke, aphtha, aphonia, toothache, etc. In contrast, in the southwest inland regions, vine tea is mostly used to clear away heat and toxic materials, antiphlogosis and relieving sore-throat, lowering blood pressure and lipid levels, and alleviating fatigue. Three main species have been used as the source of vine tea, Nekemias grossedentata, Nekemias cantonensis and Nekemias megalophylla. Among them, the leaves of Nekemias grossedentata were considered as new food resource in complicance with regulations, according to the Food Safety Standards published by the Monitoring and Evaluation Department of the National Health and Family Planning Commission in China.

AIM OF THE STUDY

At present, the comprehensively summary of Materia Medica on the history and source of vine tea is currently unavailable. The current article summed up the Materia Medica, species origin and pharmacological effects of all 3 major species used in vine tea to fill the knowledge gaps. We also aim to provide a reference for future research on historical textual, resource development and medicinal utilization of vine tea.

MATERIALS AND METHODS

Adhering to the literature screening methodology outlined by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this review encompasses 148 scholarly research papers from three database, paper ancient books, local chronicles and folklore through field investigations. We then comprehensively summarized and discussed research progresses in scientific and application studies of vine tea.

RESULTS

The historical records indicated that vine tea could have been used as early as Southern and Northern Dynasties (AC 420-589). Nekemias grossedentata, Nekemias cantonensis and Nekemias megalophylla, were used to considered as vine tea in the ethnic medicine. The main phytochemicals found in three plants are flavonoids, polyphenols and terpenoids, among which dihydromyricetin (DHM) is the most important and most studied active substance. The key words "Ampelopsis grossedentata" (Synonym of Nekemias grossedentata) and "dihydromyricetin/DHM" showed the highest frequency over the last 27 year based on the research trend analysis. And the ethnopharmacology studies drawn the main activities of vine tea are antioxidant, antibacterial, hepatoprotective, neuroprotective and anti-atherosclerosis activities.

CONCLUSIONS

This review systematically summarized and discussed vine tea from the following five aspects, history, genetic relationship, phytochemistry, research trend and ethnopharmacology. Vine tea has a long historical usage in Chinese ethnic medicine. Its outstanding therapeutic efficacies have attracted extensive attention in other places in the world at present. Nekemias cantonensis and Nekemias megalophylla are quite similar to Nekemias grossedentata in terms of many aspects. However, the current research has a narrow focus on mainly Nekemias grossedentata and DHM. We propose that future studies could be carried out to determine the synergistic effect of multi-components and multi-targets of vine tea including all 3 species to provide valuable knowledge.

Multi-omics network analysis on samples from sequential biopsies reveals vital role of proliferation arrest for Macrosteatosis related graft failure in rats after liver transplantation

To investigate the molecular impact of graft MaS on post-transplant prognosis, based on multi-omics integrative analysis. Rats were fed by methionine-choline deficient diet (MCD) for MaS grafts. Samples were collected from grafts by sequential biopsies. Transcriptomic and metabolomic profilings were assayed. Post-transplant MaS status showed a close association with graft failure. Differentially expressed genes (DEGs) for in-vivo MaS were mainly enriched on pathways of cell cycle and DNA replication. Post-transplant MaS caused arrests of graft regeneration via inhibiting the E2F1 centered network, which was confirmed by an in vitro experiment. Data from metabolomics assays found insufficient serine/creatine which is located on one‑carbon metabolism was responsible for MaS-related GF. Pre-transplant MaS caused severe fibrosis in long-term survivors. DEGs for grafts from long-term survivors with pre-transplant MaS were mainly enriched in pathways of ECM-receptor interaction and focal adhesion. Transcriptional regulatory network analysis confirmed SOX9 as a key transcription factor (TF) for MaS-related fibrosis. Metabolomic assays found elevation of aromatic amino acid (AAA) was a major feature of fibrosis in long-term survivors. Graft MaS in vivo increased post-transplant GF via negative regulations on graft regeneration. Pre-transplant MaS induced severe fibrosis in long-term survivors via activations on ECM-receptor interaction and AAA metabolism.

Effects of dietary supplementation with microencapsulated Galla chinensis tannins on growth performance, antioxidant capacity, and lipid metabolism of young broiler chickens

This study aimed to investigate the impacts of dietary supplementation with Galla chinensis tannins (GCT) on the growth performance, antioxidant capacity, and lipid metabolism of young broilers. Overall, a total of 216 healthy 1 day-old broilers were randomly allocated to CON group and GCT group, and provided with a basal diet or a basal diet added with 300 mg/kg microencapsulated GCT, respectively, in a 21 days trial. Our findings indicated that dietary GCT addition had no significant effects (p > 0.05) on growth performance. However, GCT supplementation led to a significant reduction in the total cholesterol (TC) concentration in the serum and liver (p < 0.05). Furthermore, GCT supplementation significantly increased the ratios of high-density lipoprotein (HDL) to low-density lipoprotein (LDL) and HDL to TC in the serum, in addition to elevating the activities of enzymes related to lipid metabolism in the liver (p < 0.05). Dietary GCT addition also improved the antioxidant capacity of the broilers, as evidenced by a significant decrease in the concentration of malondialdehyde in serum and liver (p < 0.05). Additionally, the GCT group exhibited significantly increased expressions of hepatic genes associated with antioxidant enzymes (HO-1, GPX1, SOD2, SIRT1, CPT-1, and PPARα) (p < 0.05), while the mRNA expression of SREBP-1 was significantly decreased (p < 0.05) compared with the CON group. In conclusion, dietary addition of 300 mg/kg microencapsulated GCT improved the antioxidant status and lipid metabolism of broilers without affecting their growth performance.

Performance and mechanism of co-culture of Monascus purpureus, Lacticaseibacillus casei, and Saccharomyces cerevisiae to enhance lovastatin production and lipid-lowering effects

To facilitate lipid-lowering effects, a lovastatin-producing microbial co-culture system (LPMCS) was constituted with a novel strain Monascus purpureus R5 in combination with Lacticaseibacillus casei S5 and Saccharomyces cerevisiae J7, which increased lovastatin production by 54.21% compared with the single strain R5. Response Surface Methodology (RSM) optimization indicated lovastatin yield peaked at 7.43 mg/g with a fermentation time of 13.88 d, water content of 50.5%, and inoculum ratio of 10.27%. Meanwhile, lovastatin in LPMCS co-fermentation extracts (LFE) was qualitatively and quantitatively analyzed by Thin-Layer Chromatography (TLC) and High-Performance Liquid Chromatography (HPLC). Cellular experiments demonstrated that LFE exhibited no obvious cytotoxicity to L-02 cells and exhibited excellent biosafety. Most notably, high-dose LFE (100 mg/L) exhibited the highest reduction of lipid accumulation, total cholesterol, and triglycerides simultaneously in oleic acid-induced L-02 cells, which decreased by 71.59%, 38.64%, and 58.85% than untreated cells, respectively. Overall, LPMCS provides a potential approach to upgrade the lipid-lowering activity of Monascus-fermented products with higher health-beneficial effects.

Dihydromyricetin ameliorated nonalcoholic steatohepatitis in mice by regulating the composition of serous lipids, bile acids and ileal microflora

BACKGROUND

Dihydromyricetin (DMY) is a natural flavonoid with anti-nonalcoholic steatohepatitis (NASH) activity. However, the effects of DMY on the composition of lipids and bile acids (BAs) in serum, and gut microbiota (GM) in ileum of mice with NASH are not clear.

METHODS

After male C57BL/6 mice was fed with methionine and choline deficiency (MCD) diet and simultaneously administered with DMY (300 mg/kg/day) by gavage for 8 weeks, the pathological changes of liver tissue were observed by Oil Red O, hematoxylin eosin and Masson staining, the levels of serum alaninea minotransferase, aspartate aminotransferase and liver triglyceride, malonic dialdehyde were detected by the detection kits, the composition and contents of serum lipids and BAs were detected by Liquid Chromatograph-Mass Spectrometry, the mRNA levels of hepatic BAs homeostasis-related genes were detected by RT-qPCR, and microbiological diversity in ileum was analyzed by 16S rDNA sequencing.

RESULTS

The results showed that the significant changes including 29 lipids, 4 BAs (23-nor-deoxycholic acid, ursodeoxycholic acid, 7-ketodeoxycholic acid and cholic acid), 2 BA transporters (Mrp2 and Oatp1b2) and 8 GMs between MCD and DMY groups. Among them, DMY treatment significantly down-regulated 21 lipids, 4 BAs mentioned above, the ratio of Firmicutes/Bacteroidota and the abundance of Erysipelotrichaceae, Faecalibacuium, significantly up-regulated 8 lipids and 5 GMs (Verrucomicrobiota, Bacteroidota, Actinobacteria, Akkermansiaceae and Akkermansia).

CONCLUSIONS

The results suggested that DMY may alleviate MCD diet-induced NASH through decreasing the serum levels of toxic BAs which regulated by liver Oatp1b2 and Mrp2, regulating the metabolism of related lipids, and up-regulating intestinal probiotics (Actinobacteria and Verrucomicrobiota at the phylum level; Akkermansiaceae at the family level; Akkermansiaat at the genus level) and inhibiting intestinal harmful bacteria (Firmicutes at the phylum level; Erysipelotrichaceae at the family level; Faecalibaculum at the genus level).

Molecular mechanisms and promising role of dihydromyricetin in cardiovascular diseases

Vine tea, a Chinese herbal medicine, is widely used in traditional Asian medicine to treat common health problems. Dihydromyricetin (DMY) is the main functional flavonoid compound extracted from vine tea. In recent years, preclinical studies have focused on the potential beneficial effects of dihydromyricetin, including glucose metabolism regulation, lipid metabolism regulation, neuroprotection, and anti-tumor effects. In addition, DMY may play a role in cardiovascular disease by resisting oxidative stress and participating in the regulation of inflammation. This review is the first review that summaries the applications of dihydromyricetin in cardiovascular diseases, including atherosclerosis, myocardial infarction, myocardial hypertrophy, and diabetic cardiomyopathy. We also clarified the underlying mechanisms and signaling pathways involved in the above process. The aim of this review is to provide a better understanding and quick overview for future researches of dihydromyricetin in the field of cardiovascular diseases, and more detailed and robust researches are needed for evaluation and reference.

Aqueous extract of Artemisia capillaris improves non-alcoholic fatty liver and obesity in mice induced by high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and is a nutritional metabolic disease. Artemisia capillaris (AC) is the above-ground dried part of Artemisia capillaris Thunb. or Artemisia scoparia Waldst. et Kit., a natural medicinal plant with pharmacological effects of heat-clearing and biliary-promoting. In order to evaluate the therapeutic effect of Artemisia capillaris on NAFLD and obesity, experiments were conducted using aqueous extracts of Artemisia capillaris (WAC) to intervene in NAFLD models in vivo and in vitro. In vivo experiments were performed using HFD-fed (high fat diet) C57BL/6 mice to induce NAFLD model, and in vitro experiments were performed using oleic acid to induce HepG2 cells to construct NAFLD cell model. H.E. staining and oil red O staining of liver tissue were used to observe hepatocytes. Blood biochemistry analyzer was used to detect serum lipid levels in mice. The drug targets and mechanism of action of AC to improve NAFLD were investigated by western blotting, qRT-PCR and immunofluorescence. The results showed that C57BL/6 mice fed HFD continuously for 16 weeks met the criteria for NAFLD in terms of lipid index and hepatocyte fat accumulation. WAC was able to reverse the elevation of serum lipid levels induced by high-fat diet in mice. WAC promoted the phosphorylation levels of PI3K/AKT and AMPK in liver and HepG2 cells of NAFLD mice, inhibited SREBP-1c expression, reduced TG and lipogenesis, and decreased lipid accumulation. In summary, WAC extract activates PI3K/AKT pathway, reduces SREBP-1c protein expression by promoting AMPK phosphorylation, and decreases fatty acid synthesis and TG content in hepatocytes. AC can be used as a potential health herb to improve NAFLD and obesity.

BCATc inhibitor 2 ameliorated mitochondrial dysfunction and apoptosis in oleic acid-induced non-alcoholic fatty liver disease model

Nonalcoholic fatty liver disease (NAFLD) is a prevalent hepatic disease in the world. Disorders of branched chain amino acid (BCAA) metabolism is involved in various diseases. In this study, we aim to explore the role of BCAA metabolism in the development of NAFLD and the protective effect of BCATc Inhibitor 2, an inhibitor of cytosolic branched chain amino acid transaminase, against NAFLD as well as its underlying mechanism. It was found that oleic acid induced lipid accumulation and apoptosis in HepG2 and LO2 cells. Supplementation of BCAAs further aggravated oleic acid-induced lipid accumulation and apoptosis. In contrast, treatment of BCATc Inhibitor 2 ameliorated oleic acid-induced lipid accumulation and apoptosis. Molecularly, supplementation of BCAAs or treatment of BCATc Inhibitor 2 up-regulated or down-regulated the expression of SREBP1 and lipogenesis-related genes without affecting lipolysis-related genes. BCATc Inhibitor 2 maintained mitochondrial function by ameliorating oleic acid-induced mitochondrial ROS generation and mitochondrial membrane potential disruption. In addition, BCATc Inhibitor 2 treatment alleviated oleic acid-induced activation of JNK and AKT signaling pathway and Bcl2/Bax/Caspase axis. In conclusion, our results indicate BCAA metabolism is involved in NAFLD and BCATc Inhibitor 2 protects against oleic acid-induced lipid accumulation and apoptosis. These findings suggest that BCATc Inhibitor 2 is a promising candidate drug for the treatment of NAFLD.

Primary Broiler Hepatocytes for Establishment of a Steatosis Model

Fatty liver hemorrhage syndrome (FLHS) in chickens is characterized by steatosis and bleeding in the liver, which has caused huge losses to the poultry industry. This study aimed to use primary cultured broiler hepatocytes to establish a steatosis model to explore the optimal conditions for inducing steatosis by incubating the cells with a fat emulsion. Primary hepatocytes were isolated from an AA broiler by a modified two-step in situ perfusion method. Hepatocytes were divided into an untreated control group and a fat emulsion group that was incubated with 2.5, 5, 10, or 20% fat emulsion for different times to determine the optimal conditions for inducing steatosis of primary hepatocytes. Incubation of the cells with 10% fat emulsion resulted in cell viability at 48 h of 67%, which was higher than the control group and met the requirements of the model. In the second experiment, steatosis was induced by incubating hepatocytes with 10% fat emulsion for 48 h. In consequence, the apoptosis rate decreased (p > 0.05) and the concentration of ALT (p < 0.001), AST (p < 0.01), and TG (p < 0.05) increased significantly; the expression level of SREBP-1c (p < 0.05) increased, and the expression levels of PPARα (p < 0.001), CPT1 (p < 0.001), and CPT2 (p < 0.05) were lower in the fat emulsion group than in the control group. In conclusion, the induction condition was selected as 10% fat emulsion incubation for 48 h, and we successfully established a fatty liver degeneration model for broilers.

Hepatoprotective Activity of Nelumbo nucifera Gaertn. Seedpod Extract Attenuated Acetaminophen-Induced Hepatotoxicity

The aim is to investigate the effect of lotus (Nelumbo nucifera Gaertn.) seedpod extract (LSE) on acetaminophen (APAP)-induced hepatotoxicity. LSE is rich in polyphenols and has potent antioxidant capacity. APAP is a commonly used analgesic, while APAP overdose is the main reason for drug toxicity in the liver. Until now, there has been no in vitro test of LSE in drug-induced hepatotoxicity responses. LSEs were used to evaluate the effect on APAP-induced cytotoxicity, ROS level, apoptotic rate, and molecule mechanisms. The co-treatment of APAP and LSEs elevated the survival rate and decreased intracellular ROS levels on HepG2 cells. LSEs treatment could significantly reduce APAP-induced HepG2 apoptosis assessed by DAPI and Annexin V/PI. The further molecule mechanisms indicated that LSEs decreased Fas/FasL binding and reduced Bax and tBid to restore mitochondrial structure and subsequently suppress downstream apoptosis cascade activation. These declines in COX-2, NF-κB, and iNOS levels were observed in co-treatment APAP and LSEs, which indicated that LSEs could ameliorate APAP-induced inflammation. LSE protected APAP-induced apoptosis by preventing extrinsic, intrinsic, and JNK-mediated pathways. In addition, the restoration of mitochondria and inflammatory suppression in LSEs treatments indicated that LSEs could decrease oxidative stress induced by toxic APAP. Therefore, LSE could be a novel therapeutic option for an antidote against overdose of APAP.

Stability profiling and degradation products of dihydromyricetin in Dulbecco's modified eagle's medium

Dihydromyricetin has shown many bioactivities in cell level. However, dihydromyricetin was found to be highly instable in cell culture medium DMEM. Here, the underlying degradation mechanism was investigated via UPLC-MS/MS analysis. Dihydromyricetin was mainly converted into its dimers and oxidized products. At lower temperature, dihydromyricetin in DMEM showed higher stability. Vitamin C increased the stability of dihydromyricetin in DMEM probably due to its high antioxidant potential.

Hesperidin attenuates hepatic lipid accumulation in mice fed high-fat diet and oleic acid induced HepG2 via AMPK activation

AIMS

In recent years, more and more people are suffering from lifestyle-related disease such as nonalcoholic fatty liver disease (NAFLD) because of unhealthy diet and lack of physical exercise. Hesperidin (HDN) is a flavonoid found in high concentrations in citrus fruits. In this study, we investigated the effect of HDN on NAFLD, providing information to develop dietary supplements for NAFLD treatment and prevention.

MATERIALS AND METHODS

Testing kits, hematoxylin-eosin staining, oil red O staining, western blot, immunofluorescence, cck-8 assay, and blood biochemical analysis were carried out during the experiments in vivo and in vitro.

KEY FINDINGS

The current study revealed that HDN significantly reduced liver index and serum lipid levels, and protected against liver steatosis and injury induced by HFD. In addition, HDN suppressed oil acid induced intracellular lipid accumulation in HepG2 cells. Moreover, HDN increased the expression level of pAMPK and downregulated SREBP-1C, ACC and FAS expression in vivo and in vitro.

SIGNIFICANCE

In summary, HDN attenuates lipid accumulation in vivo and in vitro via AMPK activation, suggesting that HDN may serve as a potential therapeutic agent for treating NAFLD.

[Dihydromyricetin reduces lipid accumulation in LO2 cells via AMPK/mTOR-mediated lipophagy pathway and inhibits HepG2 cell proliferation in vitro]

OBJECTIVE

To explore the mechanism underlying the hepatoprotective effect of dihydromyricetin (DMY) against lipid accumulation in light of the lipophagy pathway and the inhibitory effect of DMY on HepG2 cell proliferation.

METHODS

LO2 cells were cultured in the presence of 10% FBS for 24 h and treated with 100 μg/mL DMY, or exposed to 50% FBS for 24 h followed by treatment with 50, 100, or 200 μg/mL DMY; the cells in recovery group were cultured in 50% FBS for 24 h and then in 10% FBS for another 24 h. Oil red O staining was used to observe the accumulation of lipid droplets in the cells, and the levels of TC, TG, and LDL and activities of AST, ALT and LDH were measured. The expression of LC3 protein was detected using Western blotting. AO staining and transmission electron microscopy were used to determine the numbers of autophagolysosomes and autophagosomes, respectively. The formation of autophagosomes was observed with MDC staining, and the mRNA expression levels of LC3, ATG7, AMPK, mTOR, p62 and Beclin1 were determined with q-PCR. Flow cytometry was performed to analyze the effect of 50, 100, and 200 μg/mL DMY on cell cycle and apoptosis of HepG2 cells; DNA integrity in the treated cells was examined with cell DNA fragmentation test.

RESULTS

DMY treatment and pretreatment obviously inhibited lipid accumulation and reduced the levels of TC, TG, LDL and enzyme activities of AST, ALT and LDH in LO2 cells (P < 0.05). In routinely cultured LO2 cells, DMY significantly promoted the formation of autophagosomes and autophagolysosomes and upregulated the expression of LC3 protein. DMY obviously attenuated high FBS-induced inhibition of autophagosome formation in LO2 cells, up- regulated the mRNA levels of LC3, ATG7, Beclin1 and AMPK, and downregulated p62 and mTOR mRNA levels (P < 0.05 or 0.01). In HepG2 cells, DMY caused obvious cell cycle arrest, inhibited cell proliferation, and induced late apoptosis and DNA fragmentation.

CONCLUSION

DMY reduces lipid accumulation in LO2 cells by regulating the AMPK/ mTOR-mediated lipophagy pathway and inhibits the proliferation of HepG2 by causing cell cycle arrest and promoting apoptosis.

Comparative effects of sesame lignans (sesamin, sesamolin, and sesamol) on oxidative stress and lipid metabolism in steatosis HepG2 cells

Non-alcoholic fatty liver disease (NAFLD) can be attributed to the imbalance between lipogenesis and lipidolysis in the liver. Sesame lignans (sesamin, sesamolin, and sesamol) are unique bioactive compounds responsible for the nutritional function of sesame oils. However, the preventive effects of three lignans on oxidative stress and lipid metabolism in steatosis HepG2 cells have not been compared. In this study, we investigated the role of sesamin, sesamolin, and sesamol on hepatic lipid accumulation and explored the underlying mechanism via a well-established cell model. The results showed that 3 μg/ml of lignans could decrease the TG/TC contents and alleviate cellular oxidative stress, with an order of the lipid-lowering effect as sesamol > sesamin > sesamolin. The lignan-activated AMPK and PPAR signaling pathways enhanced gene and protein expressions related to fatty acid oxidation, cholesterol efflux, and catabolism. Meanwhile, treatment of the steatosis HepG2 cells with sesamin, sesamolin, and sesamol reduced lipid synthesis and cholesterol uptake, thus lowering intracellular lipogenesis in the process of NAFLD. Our data suggested that sesame lignans can attenuate oxidative stress and regulate lipid metabolism in liver cells, which may be potential therapeutic agents for treating the NAFLD. PRACTICAL APPLICATIONS: The present work demonstrated that sesame lignans can be used for dietary supplements or functional additives with excellent lipid-lowering effects. Furthermore, this study supplied potential molecular mechanisms involved in NAFLD treatment process, and also provided nutritional guidelines for sesame oil evaluation and selection.

Effect of dietary dihydromyricetin supplementation on lipid metabolism, antioxidant capacity and skeletal muscle fiber type transformation in mice

This study aimed to investigate the effect of dietary dihydromyricetin (DHM) supplementation on lipid metabolism, antioxidant capacity and muscle fiber type transformation. Twenty-four male Kunming mice were randomly allotted to either control (basal diet) or DHM diets (supplemented with 300 mg/kg DHM). Our data showed that DHM administration decreased the triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) contents, and increased the catalase (CAT), total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activities in serum. In the liver, DHM decreased the TG and malondialdehyde (MDA) levels and increased the T-SOD and GSH-Px activities. For the tibialis anterior (TA) muscle, DHM increased the total antioxidant capacity (T-AOC) level and T-SOD activities. Western blotting and real-time quantitative PCR analysis showed that DHM increased the protein and mRNA levels of MyHC I and MyHC IIa and decreased the protein and mRNA levels of MyHC IIb in TA muscle, which may be achieved by activating the AMP-activated protein kinase (AMPK) signal. The mRNA levels of several regulatory factors related to mitochondrial function were up-regulated by DHM. In conclusion, dietary 300 mg/kg DHM supplementation improved lipid metabolism and antioxidant capacity and promoted the transformation of muscle fiber type from glycolysis to oxidation in mice.

Sesamol ameliorates hepatic lipid accumulation and oxidative stress in steatosis HepG2 cells via the PPAR signaling pathway

Non-alcoholic fatty liver disease (NAFLD) is a chronic hepatopathy caused by disordered lipid metabolism in the liver. Sesamol, a phenolic compound derived from sesame oil, has been shown to inhibit obesity, hyperlipidemia, and atherosclerosis in previous investigations. However, the preventive effect of sesamol against hepatic steatosis and oxidative stress in NAFLD has not been well-studied. In this work, sesamol was observed to alleviate lipid accumulation and oxidative stress in high oleic acid (300 μM)/cholesterol (25 μM) induced HepG2 cells, thus indicating that sesamol was involved in regulating hepatic lipid metabolism and oxidative injury. Mechanism studies found that the activated peroxisome proliferator-activated receptors (PPAR) signaling pathway by sesamol intervention up-regulated gene and protein expressions related to fatty acid oxidation and cholesterol efflux and catabolism, thus accelerating lipid consumption and reducing intracellular lipid accumulation in the process of NAFLD. These data suggested that sesamol can effectively ameliorate hepatic steatosis and sesamol riched sesamol oil may be a potential agent for finding therapeutic strategies to treat the NAFLD. PRACTICAL APPLICATIONS: Sesamol and sesamol-rich sesame oil have received much attention due to their performance on hepatic lipid regulation. The results of this study indicate that sesamol treatment could ameliorate hepatic steatosis by inhibiting lipid accumulation and oxidative stress, thus demonstrating that sesamol and sesame oil can be used for functional foods and nutraceutical applications in the future. In addition, the present work provides knowledge of the effects of sesamol on NAFLD and involved mechanisms, and further supplies nutritional guidelines for sesame oil consumption.

Lily bulbs' polyphenols extract ameliorates oxidative stress and lipid accumulation in vitro and in vivo

BACKGROUND

Polyphenols have the potential to reduce the risk of many metabolic disorders. Lily bulbs are rich in polyphenols; however, their effects on lipid metabolism remain unclear. This study aimed to explore the effects of lily bulbs' polyphenols (LBPs) on oxidative stress and lipid metabolism.

RESULTS

A total of 14 polyphenolic compounds in LBPs were identified by high-performance liquid chromatography equipped with diode-array detection mass spectrometry. Total phenolic compound in LBPs was 53.76 ± 1.12 g kg^-1 dry weight. In cellular experiments, LBPs attenuated the disruption of mitochondrial membrane potential, impeded reactive oxygen species production, alleviated oxidative stress, and reduced lipid accumulation in oleic acid induced HepG2 cells. In in vivo studies, LBPs significantly inhibited body weight gain, reduced lipid levels in serum and liver, and improved oxidative damage in a dose-dependent manner in mice fed a high-fat diet. Moreover, LBPs ameliorated hepatic steatosis and suppressed the expression of hepatic-lipogenesis-related genes (SREBP-1c, FAS, ACC1, and SCD-1) and promoted lipolysis genes (SRB1 and HL) and lipid oxidation genes (PPARα and CPT-1) in mice fed a high-fat diet.

CONCLUSION

It was concluded that LBPs are a potential complementary therapeutic alternative in the development of functional foods to curb obesity and obesity-related diseases, such as metabolic syndrome. © 2021 Society of Chemical Industry.

Lipid overload impairs hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in large yellow croaker (Larimichthys crocea)

Lipid overload-induced hepatic steatosis is a major public health problem worldwide. However, the potential molecular mechanism is not completely understood. Herein, we found that high-fat diet (HFD) or oleic acid (OA) treatment induced oxidative stress which prevented the entry of hepatocyte nuclear factor 4 alpha (HNF4α) into the nucleus by activating protein kinase C delta (PKCδ) in vivo and in vitro in large yellow croaker (Larimichthys crocea). This reduced the level of microsomal triglyceride transfer protein (MTP) transcription, resulting in the impaired secretion of very-low-density lipoprotein (VLDL) and the abnormal accumulation of triglyceride (TG) in hepatocytes. Meanwhile, the detrimental effects induced by lipid overload could be partly alleviated by pretreating hepatocytes with Go6983 (PKCδ inhibitor) or N-acetylcysteine (NAC, reactive oxygen species (ROS) scavenger). In conclusion, for the first time, we revealed that lipid overload impaired hepatic VLDL secretion via oxidative stress-mediated PKCδ-HNF4α-MTP pathway in fish. This study may provide critical insights into potential intervention strategies against lipid overload-induced hepatic steatosis of fish and human beings.

Molecular mechanisms and therapeutic implications of dihydromyricetin in liver disease

Recent studies demonstrated that dihydromyricetin (DHM) has prominent therapeutic effects on liver injury and liver cancer. By summarizing the current preclinical in vitro and in vivo studies, the present review examines the preventive and therapeutic effects of DHM on liver disorders as well as its potential mechanisms. Briefly, in both chemical- and alcohol-induced liver injury models, DHM ameliorates hepatocyte necrosis and steatosis while promoting liver regeneration. In addition, DHM can alleviate nonalcoholic fatty liver disease (NAFLD) via regulating lipid/glucose metabolism, probably due to its anti-inflammatory or sirtuins-dependent mechanisms. Furthermore, DHM treatment inhibits cell proliferation, induces apoptosis and autophagy and regulates redox balance in liver cancer cells, thus exhibiting remarkable anti-cancer effects. The pharmacological mechanisms of DHM may be associated with its anti-inflammatory, anti-oxidative and apoptosis-regulatory benefits. With the accumulating interests in utilizing natural products to target common diseases, our work aims to improve the understanding of DHM acting as a novel drug candidate for liver diseases and to accelerate its translation from bench to bedside.

A Novel Dual Drug Approach That Combines Ivermectin and Dihydromyricetin (DHM) to Reduce Alcohol Drinking and Preference in Mice

Alcohol use disorder (AUD) affects over 18 million people in the US. Unfortunately, pharmacotherapies available for AUD have limited clinical success and are under prescribed. Previously, we established that avermectin compounds (ivermectin [IVM] and moxidectin) reduce alcohol (ethanol/EtOH) consumption in mice, but these effects are limited by P-glycoprotein (Pgp/ABCB1) efflux. The current study tested the hypothesis that dihydromyricetin (DHM), a natural product suggested to inhibit Pgp, will enhance IVM potency as measured by changes in EtOH consumption. Using a within-subjects study design and two-bottle choice study, we tested the combination of DHM (10 mg/kg; i.p.) and IVM (0.5–2.5 mg/kg; i.p.) on EtOH intake and preference in male and female C57BL/6J mice. We also conducted molecular modeling studies of DHM with the nucleotide-binding domain of human Pgp that identified key binding residues associated with Pgp inhibition. We found that DHM increased the potency of IVM in reducing EtOH consumption, resulting in significant effects at the 1.0 mg/kg dose. This combination supports our hypothesis that inhibiting Pgp improves the potency of IVM in reducing EtOH consumption. Collectively, we demonstrate the feasibility of this novel combinatorial approach in reducing EtOH consumption and illustrate the utility of DHM in a novel combinatorial approach.

S-adenosylmethionine upregulates the angiotensin receptor-binding protein ATRAP via the methylation of HuR in NAFLD

Nonalcoholic fatty liver disease (NAFLD) has emerged globally and is associated with inflammatory signaling. The underlying mechanisms remain poorly delineated, although NAFLD has attracted considerable attention and been extensively investigated. Recent publications have determined that angiotensin II (Ang II) plays an important role in stimulating NAFLD progression by causing lipid metabolism disorder and insulin resistance through its main receptor, Ang II type 1 receptor (AT1R). Herein, we explored the effect of supplementary S-adenosylmethionine (SAM), which is the main biological methyl donor in mammalian cells, in regulating AT1R-associated protein (ATRAP), which is the negative regulator of AT1R. We found that SAM was depleted in NAFLD and that SAM supplementation ameliorated steatosis. In addition, in both high-fat diet-fed C57BL/6 rats and L02 cells treated with oleic acid (OA), ATRAP expression was downregulated at lower SAM concentrations. Mechanistically, we found that the subcellular localization of human antigen R (HuR) was determined by the SAM concentration due to protein methylation modification. Moreover, HuR was demonstrated to directly bind ATRAP mRNA and control its nucleocytoplasmic shuttling. Thus, SAM was suggested to upregulate ATRAP protein expression by maintaining the export of its mRNA from the nucleus. Taken together, our findings suggest that SAM can positively regulate ATRAP in NAFLD and may have various potential benefits for the treatment of NAFLD.

Major royal jelly proteins prevents NAFLD by improving mitochondrial function and lipid accumulation through activating the AMPK / SIRT3 pathway in vitro

Nonalcoholic fatty liver disease (NAFLD) is a metabolic syndrome, whose main characteristics are excessive lipid accumulation and oxidative stress. Major royal jelly proteins (MRJPs) is a kind of water-soluble protein, which is abundant in royal jelly (RJ). The aim of this study was to evaluate the effect of MRJPs on lipid accumulation and oxidative stress of liver cells. Here, we first optimized the conditions for extracting MRJPs from RJ and identified the extraction effect and product by SDS-PAGE. Then, we used oleic acid (OA) of 1.0 mM to induce hepatocytes for 24 hr to establish a stable cell models of lipid accumulation, and we found that pre-administration (24 hr) of MRJPs (0.2, 0.5, and 1.0 g/L) could significantly reduce the lipid drop content and triglyceride level in the model cells, and simultaneously reduce the alanine aminotransferase and aspertate aminotransferase levels in the cell culture supernatant. In addition, pre-incubation (24 hr) with MRJPs (0.2, 0.5, and 1.0 g/L) could restore superoxide dismutase (SOD) level and mitochondrial membrane potential as compared with OA group. Furthermore, MRJPs administration significantly upregulated the expression of Silent Information Regulator 2 Associated Protein 3, mitochondrial superoxide dismutase (SOD2), and cytochrome c oxidase subunit IV in OA-treated HepG2 cells. The study for the first time provides evidences on the lipid-lowering effect of MRJPs at the cellular level, which can further provide support for the development and application of polypeptide drugs in the future, and can also provide a choice for the prevention and treatment of liver metabolic diseases represented by NAFLD. PRACTICAL APPLICATION: Our study proved that MRJPs had substantial preventing effect on OA-induced lipid accumulation and mitochondrial dysfunction in HepG2 cells. This research can further provide theoretical support for the development and application of peptide drugs in the future. Besides, it can not only further broaden our understanding of NAFLD and other diseases, but also provide ideas for research on oxidative stress and lipid accumulation in the body.

New insight and potential therapy for NAFLD: CYP2E1 and flavonoids

Over the years, the prevalence of nonalcoholic fatty liver disease (NAFLD) has increased year by year; however, due to its complicated pathogenesis, there is no effective treatment so far. It is reported that Cytochrome P450 2E1 (CYP2E1) plays an indispensable role in the development of NAFLD, and numerous studies have shown that flavonoids have a hepatoprotective effect and can exert a beneficial effect on NAFLD by regulating the activity of CYP2E1. Therefore, flavonoids may become effective drugs for the treatment of NAFLD in the future. This prompted us to review the research progress of the pathological mechanism of NAFLD and the impact of CYP2E1 activity changes during the pathological process, and to summarize the protective effect of flavonoids against CYP2E1 activity.

Antioxidant Capacity of Proteins and Hydrolysates from the Liver of Newborn Piglets, and Their Inhibitory Effects on Steatosis in vitro

Research background

Non-alcoholic steatohepatitis is a potentially progressive hepatic disorder that can lead to end-stage liver disease and hepatocellular carcinoma. The inhibitory effects of proteins and hydrolysates from the liver of newborn piglets on hepatic steatosis in oleic acid-induced hepatocellular carcinoma (HepG2) cells were investigated in vitro.

Experimental approach

The extracted proteins from the liver of newborn piglets were hydrolysed with papain, pepsin, trypsin and Alcalase. Based on the comparison of different enzyme digestion conditions, a protein hydrolysis protocol was established to obtain hydrolysates with lipid-lowering effect.

Results and conclusions

Trypsin-digested liver protein hydrolysate from newborn piglets exhibited strong antioxidant activity and good inhibitory effects against lipogenesis and cholesterol accumulation in HepG2 cells at the concentration of 150 μg/mL, with a triglyceride decrease of (43±3) % and cholesterol decrease of (31±5) %, compared with model group induced with 0.75 mM oleic acid. The addition of trypsin-digested liver protein hydrolysate from newborn piglets (300 μg/mL) decreased alanine aminotransferase and aspartate aminotransferase activities and increased superoxide dismutase activity.

Novelty and scientific contribution

This study demonstrated that the trypsin-digested liver protein hydrolysate from newborn piglets has a potential preventive effect against non-alcoholic fatty liver disease in its early stage, and a potential use as the modulator of lipid overaccumulation in form of food supplements.

Dietary dihydromyricetin supplementation enhances antioxidant capacity and improves lipid metabolism in finishing pigs

Nowadays, chronic diseases have become a potential danger to human health and are highly concerning. Given that pigs are a suitable animal model for human nutrition and metabolism for its similar anatomical and physiological properties to those of humans, this study has used 24 castrated male Duroc × Landrace × Yorkshire (DLY) pigs as experimental subjects to explore the effects of dietary dihydromyricetin (DHM) supplementation on the antioxidant capacity and lipid metabolism. Results showed that dietary 300 and 500 mg DHM kg-1 diet supplementation increased the serum total superoxide dismutase (T-SOD) level, serum and liver reduced glutathione (GSH), muscle catalase (CAT) level and serum high-density lipoprotein cholesterol (HDL-C) level, and reduced the liver malondialdehyde (MDA) level and muscle triglyceride (TG) level in finishing pigs. Western blot analysis showed that dietary DHM supplementation activated the nuclear-related factor 2 (Nrf2) and AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) signals. Real-time quantitative PCR analysis showed that dietary DHM supplementation upregulated the mRNA levels of lipolysis and fatty acid oxidation-related genes, and down-regulated the mRNA expression of lipogenesis-related genes in finishing pigs. Together, we provide evidence that dietary DHM supplementation improved the antioxidant capacity and lipid metabolism in finishing pigs.

Dihydromyricetin Alleviates High Glucose-Induced Oxidative Stress and Apoptosis in Human Retinal Pigment Epithelial Cells by Downregulating miR-34a Expression

BACKGROUND

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes mellitus, which leads to neuronal and vascular dysfunction in the retina with a final outcome of complete loss of vision. The aim of the present study was to investigate the effects of dihydromyricetin (DHM), a natural flavanol compound, on diabetic retinopathy (DR) and identify its potential mechanisms.

METHODS

Retinal pigment epithelial cell line (ARPE-19) treated with high glucose (HG) was used to simulate the DR model in vitro. After treatment with different concentrations of DHM, the cell viability, production of reactive oxygen species (ROS) and the levels of oxidative stress-related markers in the in vitro model were detected using corresponding kits. Cell apoptosis was determined using terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining, and the expression of apoptotic proteins was examined using Western blot analysis. Subsequently, microRNA (miR)-34a expression was measured by reverse transcription-quantitative PCR (RT-qPCR). The levels of oxidative stress and apoptosis were evaluated after miR-34a overexpression.

RESULTS

Results indicated that DHM dose-dependently elevated the decreased cell viability induced by HG. Moreover, the content of ROS was significantly reduced in HG-stimulated ARPE-19 cells, accompanied by enhanced activities of superoxide dismutase (SOD) and catalase (CAT) antioxidases, as well as concentration of glutathione (GSH). Furthermore, remarkably decreased apoptosis of ARPE-19 cells induced by HG was observed following DHM intervention. Importantly, HG stimulation notably upregulated miR-34a expression, which was reversed by DHM treatment. Importantly, the inhibitory effects of DHM on HG-induced oxidative stress and apoptosis of ARPE-19 cells were restored following miR-34a overexpression.

CONCLUSION

Taken together, this work demonstrated that DHM exerts protective effects on HG-induced oxidative stress and apoptotic damage in ARPE-19 cells via inhibition of miR-34a expression, providing a promising therapeutic agent for the treatment of DR.

Phosphorylation of eIF2α signaling pathway attenuates obesity-induced non-alcoholic fatty liver disease in an ER stress and autophagy-dependent manner

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder and frequently exacerbates in postmenopausal women. In NAFLD, the endoplasmic reticulum (ER) plays an important role in lipid metabolism, in which salubrinal is a selective inhibitor of eIF2α de-phosphorylation in response to ER stress. To determine the potential mechanism of obesity-induced NAFLD, we employed salubrinal and evaluated the effect of ER stress and autophagy on lipid metabolism. Ninety-five female C57BL/6 mice were randomly divided into five groups: standard chow diet, high-fat (HF) diet, HF with salubrinal, HF with ovariectomy, and HF with ovariectomy and salubrinal. All mice except for SC were given HF diet. After the 8-week obesity induction, salubrinal was subcutaneously injected for the next 8 weeks. The expression of ER stress and autophagy markers was evaluated in vivo and in vitro. Compared to the normal mice, the serum lipid level and adipose tissue were increased in obese mice, while salubrinal attenuated obesity by blocking lipid disorder. Also, the histological severity of hepatic steatosis and fibrosis in the liver and lipidosis was suppressed in response to salubrinal. Furthermore, salubrinal inhibited ER stress by increasing the expression of p-eIF2α and ATF4 with a decrease in the level of CHOP. It promoted autophagy by increasing LC3II/I and inhibiting p62. Correlation analysis indicated that lipogenesis in the development of NAFLD was associated with ER stress. Collectively, we demonstrated that eIF2α played a key role in obesity-induced NAFLD, and salubrinal alleviated hepatic steatosis and lipid metabolism by altering ER stress and autophagy through eIF2α signaling.

Dihydromyricetin ameliorates chronic liver injury by reducing pyroptosis

BACKGROUND

Chronic liver injury (CLI) is now a worldwide disease. However, there is no effective treatment. Pyroptosis plays an essential role in CLI. Dihydromyricetin (DHM) resists oxidation and protects the liver. We hypothesize that the beneficial effect of DHM on CLI is related to its effect on the expression of pyroptosis-related molecules. Therefore, we studied the influence of DHM on CLI and pyroptosis.

AIM

To study the role of pyroptosis in the pathogenesis of CLI and the therapeutic mechanism of DHM.

METHODS

Thirty-two mice were randomly divided into four groups: The control group was injected with olive oil, the carbon tetrachloride (CCl₄) group was injected with CCl₄, the vehicle group was injected with hydroxypropyl-β-cyclodextrin while injecting CCl₄ and the DHM group was injected with DHM while injecting CCl₄. After four weeks of treatment, liver tissues from the mice were stained with hematoxylin and eosin, and oil red O. Blood was collected from the angular vein for serological analysis. The severity of CLI was estimated. Some liver tissue was sampled for immunohistochemistry, Western blotting and quantitative reverse transcription PCR to observe the changes in pyroptosis-related molecules.

RESULTS

Serum total cholesterol, low density lipoprotein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the CCl₄ group were higher than those in the control group, and serum total cholesterol, low density lipoprotein, AST and ALT in the DHM group were lower than those in the vehicle group. Hematoxylin and eosin and oil red O staining showed that there were more lipid droplets in the CCl₄ group than in the control group, and there were fewer lipid droplets in the DHM group than in the vehicle group. Western blotting showed that the expression of the pyroptosis-related molecules caspase-1, NOD-, LRR- and pyrin domain-containing 3 (NLRP3) and gasdermin D (GSDMD)-N in the CCl₄ group was higher than that in the control group, while expression of these proteins in the DHM group was lower than that in the vehicle group. Quantitative reverse transcription PCR results showed that the expression of the pyroptosis-related genes caspase-1, NLRP3, GSDMD and interleukin-1β (IL-1β) in the CCl₄ group was higher than that in the control group, while there was no significant change in NLRP3 and caspase-1 expression in the DHM group compared with that in the vehicle group, and the expression of GSDMD and IL-1β was decreased.

CONCLUSION

DHM improves CCl₄-induced CLI and regulates the pyroptosis pathway in hepatocytes. DHM may be a potential therapeutic agent for CLI.

Dihydromyricetin Protects the Liver via Changes in Lipid Metabolism and Enhanced Ethanol Metabolism

Background

Excess alcohol (ethanol, EtOH) consumption is a significant cause of chronic liver disease, accounting for nearly half of the cirrhosis‐associated deaths in the United States. EtOH‐induced liver toxicity is linked to EtOH metabolism and its associated increase in proinflammatory cytokines, oxidative stress, and the subsequent activation of Kupffer cells. Dihydromyricetin (DHM), a bioflavonoid isolated from Hovenia dulcis, can reduce EtOH intoxication and potentially protect against chemical‐induced liver injuries. But there remains a paucity of information regarding the effects of DHM on EtOH metabolism and liver protection. As such, the current study tests the hypothesis that DHM supplementation enhances EtOH metabolism and reduces EtOH‐mediated lipid dysregulation, thus promoting hepatocellular health.

Methods

The hepatoprotective effect of DHM (5 and 10 mg/kg; intraperitoneal injection) was evaluated using male C57BL/6J mice and a forced drinking ad libitum EtOH feeding model and HepG2/VL‐17A hepatoblastoma cell models. EtOH‐mediated lipid accumulation and DHM effects against lipid deposits were determined via H&E stains, triglyceride measurements, and intracellular lipid dyes. Protein expression of phosphorylated/total proteins and serum and hepatic cytokines was determined via Western blot and protein array. Total NAD⁺/NADH Assay of liver homogenates was used to detect NAD + levels.

Results

DHM reduced liver steatosis, liver triglycerides, and liver injury markers in mice chronically fed EtOH. DHM treatment resulted in increased activation of AMPK and downstream targets, carnitine palmitoyltransferase (CPT)‐1a, and acetyl CoA carboxylase (ACC)‐1. DHM induced expression of EtOH‐metabolizing enzymes and reduced EtOH and acetaldehyde concentrations, effects that may be partly explained by changes in NAD⁺. Furthermore, DHM reduced the expression of proinflammatory cytokines and chemokines in sera and cell models.

Conclusion

In total, these findings support the utility of DHM as a dietary supplement to reduce EtOH‐induced liver injury via changes in lipid metabolism, enhancement of EtOH metabolism, and suppressing inflammation responses to promote liver health.

Specific Degradation of Endogenous Tau Protein and Inhibition of Tau Fibrillation by Tanshinone IIA through the Ubiquitin-Proteasome Pathway

Alzheimer's disease (AD) is a common neurodegenerative disease which is partly characterized by the aggregation of hyperphosphorylated Tau proteins forming neurofibrillary tangles that promote AD pathogenesis. In this study, we investigated the effects of tanshinone IIA (Tan IIA) isolated from Salvia miltiorrhiza on Tau degradation in the treatment of AD. The results showed that Tan IIA reduced the Tau expression and attenuated Tau phosphorylation in N2a cells, Tau-overexpressing cells, and 3×Tg-AD mouse primary neuron cells. Moreover, Tan IIA increased polyubiquitinated Tau accumulation and induced proteasomal degradation of the Tau protein. Additionally, Tan IIA became bound to the Tau protein and inhibited the formation of heparin-induced Tau fibrils. In summary, Tan IIA can increase polyubiquitinated Tau accumulation and induce the proteasomal degradation of the Tau protein and the binding of Tan IIA to the Tau protein, inhibiting the formation of Tau fibrils. Tan IIA may be further explored as a potential candidate for AD treatment.

Multitarget and promising role of dihydromyricetin in the treatment of metabolic diseases

Dihydromyricetin (DMY or DHM), also known as ampelopsin, is the main natural flavonol compound extracted from the plant Ampelopsis grossedentata (Hand. -Mazz) W.T. Wang. In recent years, accumulating studies have been conducted to explore the extensive biological functions of DMY, including antitumor, anti-inflammation, organ-protective, and metabolic regulation effects. DMY acts as a potential preventive or therapeutic agent in treating multiple diseases, such as diabetes mellitus, atherosclerosis, nonalcoholic fatty liver disease and osteoporosis. This review article summarizes the preventive and therapeutic potential of DMY in multiple metabolic diseases and the main signaling pathways in which DMY participates to offer a comprehensive understanding and guidance for future studies.

Lotus Seedpod Extracts Reduced Lipid Accumulation and Lipotoxicity in Hepatocytes

Non-alcoholic fatty liver disease (NAFLD) is closely associated with metabolic disorders, including hepatic lipid accumulation and lipotoxicity. Plant-derived polyphenols have attracted considerable attention in the prevention of NAFLD. Lotus seedpod, rich in polyphenols, is a traditional Chinese herbal medicine. Previous studies have showed that lotus seedpod possess radioprotective, antioxidant, anti-cancer, and anti-inflammatory activities. In this study, the in vitro hepatoprotective effect of lotus seedpod extract (LSE) and its main component epigallocatechin (EGC) was examined. Firstly, oleic acid (OA), an unsaturated fatty acid, was used to induce the phenotype of NAFLD in human hepatocytes, HepG2 cells. LSE dose-dependently improved the OA-induced viability loss of HepG2 cells. Non-cytotoxic concentrations of LSE or EGC abolished intracellular lipid accumulation and oxidative stress in the OA-treated cells. In addition, LSE and EGC showed a minor effect on autophagy, and potential in reducing OA-induced occurrence of apoptosis confirmed by morphological and biochemical features, including an increase in the formation of apoptotic bodies, the exposure of phosphatidylserine, and activation of caspases. Molecular data showed the anti-apoptotic effect of LSE might be mediated via downregulation of the mitochondrial pathway. Our data imply that EGC-enriched LSE potentially could be developed as an anti-NAFLD agent.

Dihydromyricetin: A review on identification and quantification methods, biological activities, chemical stability, metabolism and approaches to enhance its bioavailability

BACKGROUND

Dihydromyricetin (DMY) is an important plant flavonoid, which has received great attention due to its health-benefiting activities, including antioxidant, antimicrobial, anti-inflammatory, anticancer, antidiabetic and neuroprotective activities. DMY capsules have been sold in US as a nutraceutical supplement to prevent alcoholic hangovers. The major disadvantage associated with DMY is its chemical instability and poor bioavailability caused by the combined effects of its low solubility and poor membrane permeability. This limits its practical use in the food and pharmaceutical fields.

SCOPE AND APPROACH

The present paper gives an overview of the current methods for the identification and quantification of DMY. Furthermore, recent findings regarding the main biological properties and chemical stability of DMY, the metabolism of DMY as well as different approaches to increase DMY bioavailability in both aqueous and lipid phases are discussed.

KEY FINDINGS AND CONCLUSIONS

Current trends on identification and quantification of DMY have been focused on spectral and chromatographic techniques. Many factors such as heat, pH, metal ions, could affect the chemical stability of DMY. Despite the diverse biological effects of DMY, DMY faces with the problem of poor bioavailability. Utilization of different delivery systems including solid dispersion, nanocapsule, microemuslion, cyclodextrin inclusion complexes, co-crystallization, phospholipid complexes, and chemical or enzymatic acylation has the potential to improve both the solubility and bioavailability. DMY digested in laboratory animals undergoes reduction, dehydroxylation, methylation, glucuronidation, and sulfation. Novel DMY delivery systems and basic pharmacokinetic studies of encapsulated DMY on higher animals and humans might be required in the future.

IGFBP5 suppresses oleate-induced intramyocellular lipids deposition and enhances insulin signaling

Excess intramyocellular lipids are often accompanied by muscle insulin resistance (IR) and type 2 diabetes. The mechanism of the formation of intramyocellular lipids is unclear yet. In this study, we optimized the cellular model of intramyocellular lipids from differentiated C2C12 cells and identified that the expression of insulin-like growth factor-binding protein 5 (IGFBP5) is diminished in this process. Then, we added exogenous recombinant IGFBP5 during myocyte triglyceride (TAG) formation and found decreased lipids accumulation. In addition, IGFBP5 could promote lipolysis when added to the cellular model after the formation of intramyocellular lipids. Moreover, IGFBP5 could enhance myocyte insulin sensitivity by inhibiting the expression of the thioredoxin-interacting protein (TXNIP) and arrestin domain-containing 4 (ARRDC4), which are a negative regulator of insulin signaling in both cases. Meanwhile, IGFBP5 also inhibited the expression of glycerol-3-phosphate acyltransferase (GPAM) and diglyceride acyltransferase 2 (DGAT2), which were involved in TAG synthesis from a fatty acid. IGFBP5 also reduced TAG storage by promoting lipolysis. Therefore, IGFBP5 may play a role in the excess accumulation of lipid in muscle cells of diabetic patients and serve as a reference for further research and treatment of muscle IR and diabetes.

Effects of daphnetin on lipid metabolism, insulin resistance and oxidative stress in OA‑treated HepG2 cells

Non‑alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease, and has high rates of morbidity and mortality worldwide. Daphnetin (DAP) possesses notable antioxidative, anti‑inflammatory and anticoagulant activities; DAP is an active ingredient extracted from Daphne Koreana Nakai. To investigate the effects and the underlying mechanism of DAP on NAFLD, we treated HepG2 cells with oleic acid (OA) and DAP simultaneously and non‑simultaneously. In the simultaneous treatment condition, HepG2 cells were co‑treated with 0.5 mM OA and DAP (5, 20, and 50 µM) for 24 h. In the non‑simultaneous treatment conditions, HepG2 cells were pretreated with 0.5 mM OA for 24 h, and then treated with DAP (5, 20 and 50 µM) for 24 h. Following the aforementioned treatments, the biochemical indexes associated with NAFLD were measured as follows: i) The intracellular contents of triglyceride (TG), reactive oxygen species (ROS) and fluorescent glucose 2‑[N‑(7‑nitrobenz‑2‑oxa‑1,3‑diazol‑4‑yl) amino]‑2‑deoxyglucose were analyzed with corresponding detection kits; and ii) the cellular expression levels of glycolipid metabolism‑ and oxidative stress‑related genes, including 5'AMP‑activated protein kinase (AMPK), sterol regulatory element‑binding protein‑1C (SREBP‑1C), patatin‑like phospholipase domain‑containing protein 3 (PNPLA3), peroxisome proliferator‑activated receptor α (PPARα), phosphoinositide 3‑kinase (PI3K), protein kinase B (AKT), nuclear factor‑like 2 (Nrf2), cytochrome P450 (CYP) 2E1 and CYP4A were determined by reverse transcription‑quantitative polymerase chain reaction and western blotting. The results revealed the potential mechanism underlying the effects of DAP on NAFLD in vitro: i) By increasing the phosphorylation of AMPK, DAP inhibited the expression of SREBP‑1C and PNPLA3, and induced that of PPARα. Lipid accumulation within hepatocytes was reduced; ii) by upregulating PI3K expression and pAKT/AKT levels, DAP may alleviate insulin resistance and promote hepatocellular glucose uptake; and iii) by upregulating the expression of Nrf2, DAP downregulated the expression of CYP2E1 and CYP4A, and the levels of reactive oxygen species in hepatocytes.

Ursodeoxycholic acid ameliorates hepatic lipid metabolism in LO2 cells by regulating the AKT/mTOR/SREBP-1 signaling pathway

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease, can progress into nonalcoholic steatohepatitis (NASH), cirrhosis, and even hepatocellular carcinoma. Bile acids such as ursodeoxycholic acid (UDCA) play an essential role in the pathogenesis of NAFLD by regulating the level of sterol regulatory element-binding protein (SREBP) 1c, but the underlying regulatory mechanism remains elusive. Increased evidence indicates that the AKT/mTOR/SREBP-1 signaling pathway is a key pathway to regulate hepatic cellular lipid metabolism. UDCA may regulate the AKT/mTOR/SREBP-1 signaling pathway to ameliorate hepatic lipid metabolism.

AIM

To investigate the functional mechanism of UDCA in an oleic acid (OA)-induced cellular model of NAFLD.

METHODS

The cellular model of NAFLD was established using OA and treated with UDCA. First, the best concentration of UDCA was selected. For the best time-dependent assay, cells were stimulated with OA only or co-treated with OA and 2 mmol/L UDCA for 24 h, 48 h, and 72 h. Oil red O staining was used to observe the accumulation of intracellular lipids, while the intracellular contents of triglyceride, alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), and aspartate aminotransferase (AST) were detected by enzymatic methods. Meanwhile, the expression levels of AKT/mTOR/SREBP-1 signaling pathway-related proteins were detected by real-time PCR and Western blot.

RESULTS

In the NAFLD cell model established with LO2 cells induced using OA, lipid accumulation was obvious. UDCA significantly inhibited lipid accumulation at different concentrations (especially 2 mmol/L) and decreased cell growth ability at different time points. The biochemical parameters like ALT, AST, and GGT were significant improved by UDCA. UDCA treatment vividly repressed the activation of AKT, mTOR, and CRTC2 and the expression of nSREBP-1 in LO2 cells induced with OA.

CONCLUSION

Our findings demonstrate the effect of UDCA in improving NAFLD. UDCA attenuates OA-induced hepatic steatosis mainly by regulation of AKT/mTOR/SREBP-1 signal transduction.

Hovenia dulcis Extract Attenuates High-Fat Diet-Induced Hepatic Lipid Accumulation and Hypertriglyceridemia in C57BL/6 Mice

The effects of dietary supplementation with aqueous Hovenia dulcis Thunb. extract (HDE) (20 weeks) on high-fat diet (HFD)-induced nonalcoholic fatty liver disease and dyslipidemia were evaluated in mice. Supplementation with 200 and 800 mg/kg feed HDE (HDE200 and HDE800, respectively) resulted in no significant difference in growth in the HFD-fed groups. The triglyceride (TG) levels and free fatty acids were significantly decreased, whereas high-density lipoprotein cholesterol was increased in the HDE800 group (P < .05). The hepatic intracellular TGs were significantly decreased in the HDE-fed groups and lipogenic enzymes (acetyl CoA carboxylase, fatty acid synthase, stearoyl CoA desaturase, and diacylglycerol transferase) in the liver were significantly downregulated by HDE supplementation (P < .05). The diminished serum antioxidant enzyme activities in the HFD group were effectively restored by HDE supplementation, which also contributed to the attenuation of hyperlipidemia.

Dihydromyricetin Attenuates Myocardial Hypertrophy Induced by Transverse Aortic Constriction via Oxidative Stress Inhibition and SIRT3 Pathway Enhancement

Dihydromyricetin (DMY), one of the flavonoids in vine tea, exerts several pharmacological actions. However, it is not clear whether DMY has a protective effect on pressure overload-induced myocardial hypertrophy. In the present study, male C57BL/6 mice aging 8⁻10 weeks were subjected to transverse aortic constriction (TAC) surgery after 2 weeks of DMY (250 mg/kg/day) intragastric administration. DMY was given for another 2 weeks after surgery. Blood pressure, myocardial structure, cardiomyocyte cross-sectional area, cardiac function, and cardiac index were observed. The level of oxidative stress in the myocardium was assessed with dihydroethidium staining. Our results showed that DMY had no significant effect on the blood pressure. DMY decreased inter ventricular septum and left ventricular posterior wall thickness, relative wall thickness, cardiomyocyte cross-sectional areas, as well as cardiac index after TAC. DMY pretreatment also significantly reduced arterial natriuretic peptide (ANP), brain natriuretic peptide (BNP) mRNA and protein expressions, decreased reactive oxygen species production and malondialdehyde (MDA) level, while increased total antioxidant capacity (T-AOC), activity of superoxide dismutase (SOD), expression of sirtuin 3 (SIRT3), forkhead-box-protein 3a (FOXO3a) and SOD2, and SIRT3 activity in the myocardium of mice after TAC. Taken together, DMY ameliorated TAC induced myocardial hypertrophy in mice related to oxidative stress inhibition and SIRT3 pathway enhancement.

Cytochrome P450 1A1 (CYP1A1) Catalyzes Lipid Peroxidation of Oleic Acid-Induced HepG2 Cells

Nonalcoholic fatty liver disease (NAFLD) is a chronic hepatic disease associated with excessive accumulation of lipids in hepatocytes. As the disease progresses, oxidative stress plays a pivotal role in the development of hepatic lipid peroxidation. Cytochrome P450 1A1 (CYP1A1), a subtype of the cytochrome P450 family, has been shown to be a vital modulator in production of reactive oxygen species. However, the exact role of CYP1A1 in NAFLD is still unclear. The aim of this study was to investigate the effects of CYP1A1 on lipid peroxidation in oleic acid (OA)-treated human hepatoma cells (HepG2). We found that the expression of CYP1A1 is elevated in OA-stimulated HepG2 cells. The results of siRNA transfection analysis indicated that CYP1A1-siRNA inhibited the lipid peroxidation in OA-treated HepG2 cells. Additionally, compared with siRNA-transfected and benzo[a]pyrene (BaP)-OA-induced HepG2 cells, overexpression of CYP1A1 by BaP further accelerated the lipid peroxidation in OA-treated HepG2 cells. These observations reveal a regulatory role of CYP1A1 in liver lipid peroxidation and imply CYP1A1 as a potential therapeutic target.

Effects of Rhizoma Alismatis extract on biochemical indices and adipose gene expression in oleic acid-induced hepatocyte injury in Jian carp (Cyprinus carpio var. Jian)

Fatty liver is an increasingly serious disease of fish in aquaculture. However, the mechanisms responsible for the occurrence of fatty liver remain unclear, and no effective methods for the prevention and treatment of this disease have yet been found. In the present study, we aimed to develop an in vitro model of hepatocyte injury using oleic acid as hepatotoxicant and evaluate the protective effects of Rhizoma Alismatis extract (RAE) in Jian carp using this model. Primary hepatocytes from Jian carp were isolated and purified and cultured in vitro. The result indicated that 0.4 mmol L^-1 oleic acid and 48 h could be the optimal conditions to induce hepatocyte injury model in cultured hepatocytes. Hepatocytes were exposed to oleic acid, followed by the addition of RAE at 0, 1, 5, 10, 20, or 50 μg mL^-1. The hepatocytes and supernatant were then analyzed. RAE suppressed oleic acid-induced elevations in aspartate aminotransferase, alanine aminotransferase, triglycerides, total cholesterol, lactate dehydrogenase, alkaline phosphatase, cholinesterase, malondialdehyde, γ-glutamyl transferase, cytochrome P450 1A, cytochrome P450 2E1, liver-type fatty acid binding protein, free fatty acid, fatty acid synthetase, and tumor necrosis factor-α (P < 0.01 or P < 0.05); reduced protein levels of cytochrome P450 1A, nuclear factor (NF)-κB p65, and NF-κB c-Rel; and inhibited cytochrome P4503A, NF-κB c-Rel, nuclear factor erythroid-related factor 2, peroxisome proliferator-activated receptor-α, and cytochrome P4501A mRNA levels. In conclusion, RAE exhibited a protective effect against hepatocyte injury in Jian carp. Further in vivo studies are needed to provide more evidence for the use of RAE as a hepatoprotective agent for the treatment of hepatocyte injury.

Protective effects of cichoric acid on H2O2-induced oxidative injury in hepatocytes and larval zebrafish models

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease with a broad spectrum of liver injury. Oxidant stress is believed to be the pathogenesis of NAFLD as the "second hit". Hydrogen peroxide is widely used as an oxidant reagent to induce the oxidant injury of cells and larval zebrafish. Recently, cichoric acid is being studied extensively for its obesity attenuating, hepatic steatosis reduction and anti-oxidant effects. In this study, to identify whether CRA could protect the H₂O₂ induced oxidant injury via anti-oxidant impact by using L02 and HepG2 hepatocytes as in vitro and larval zebrafish as in vivo injury models, and evaluated the protective and anti-oxidant effects of CRA by pretreated it on both in vitro and in vivo models. CRA was found to reduce the production of ROS and MDA, activate the anti-oxidant enzymes SOD and GSH-px, and pathways Keap1-Nrf2 and HO-1. These results demonstrated that CRA might protect the liver injury by its anti-oxidant effect, which could be a potential therapeutic agent of NAFLD.