Design, synthesis, and biological evaluation of novel tetrahydroprotoberberine derivatives to reduce SREBPs expression for the treatment of hyperlipidemia.

Statins play an important role in the treatment of hyperlipidemia, but drug resistance and adverse effects greatly limits their application. To discover new lipid-lowering drugs, three different series of tetrahydroprotoberberine derivatives (THPBs) were designed and synthesized. These compounds were first tested for their effects on viability of HepG2 cells and 21 compounds with the percent of cell viability over 90% were further screened to evaluate their ability to reduce total cholesterol (TC) and triglyceride (TG) levels. Among these derivatives, two compounds displayed significant down-regulation both intracellular of TC and TG content, especially compound 49 exhibited the greatest efficacy. Mechanistically, compound 49 promoted proteasomal degradation of SREBPs. Importantly, compound 49 displayed superior bioavailability (F = 65.1%) and obvious efficacy in the treatment of high fat diet induced obesity in vivo. Therefore, compound 49 is a promising candidate to develop new treatment of hyperlipidemia.

Prevention of Nonalcoholic Hepatic Steatosis by Shenling Baizhu Powder: Involvement of Adiponectin-Induced Inhibition of Hepatic SREBP-1c.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease worldwide, and its incidence is increasing annually, but there is currently no specific drug for treating NAFLD. Shenling Baizhu powder (SL) is a safe herbal compound commonly used in clinical practice. Our previous research has shown that SL has the effect of preventing NAFLD, but its specific mechanism has not been determined. In this study, the potential mechanism of SL on NAFLD was explored by in vivo experiments. METHODS: Wistar rats fed a choline-deficient amino acid-defined diet (CDAA) were treated with SL for 8 weeks. Then, serum samples were collected to obtain biochemical indicators; adipose tissue and liver samples were collected for pathological detection; a moorFLPI-2 blood flow imager was used to measure liver microcirculation blood flow, and a rat cytokine array was used to screen potential target proteins. The expression of liver adiponectin/SREBP-1c pathway-related proteins was determined by Western blotting. RESULTS: SL effectively reduced the liver wet weight, as well as the levels of total cholesterol (TC) and triglyceride (TG) in the liver, and ameliorated liver injury in CDAA-fed rats. Pathological examinations showed that SL markedly reduced liver lipid droplets and improved liver lipid accumulation. In addition, the detection of liver blood flow showed that SL increased liver microcirculation in CDAA-fed rats. Through the cytokine array, a differentially expressed cytokine, namely, adiponectin, was screened in the liver. Western blotting assays showed that SL increased the expression of adiponectin and phosphoacetyl-CoA Carboxylase (p-ACC) in the liver and decreased the expression of steroid regulatory element-binding protein-1c (SREBP-1c) and fatty acid synthase (FAS). CONCLUSION: These results suggest that SL can increase the levels of adiponectin in the liver and serum and can inhibit the expression of SREBP-1c, thereby regulating systemic lipid metabolism and reducing liver lipid accumulation.

Pseudoprotodioscin inhibits SREBPs and microRNA 33a/b levels and reduces the gene expression regarding the synthesis of cholesterol and triglycerides.

The extract of Dioscorea zingiberensis C.H. Wright rhizomes is found to be effective in the therapy of cardiovascular disease. Steroidal saponins make substantial contribution. Previous study has proposed that methylprotodioscin (MP) may promote cholesterol efflux by increasing ABCA1 expression. But the other main saponins ingredients are not referred to. The aim of the present work was to reveal the effect and mechanism of protodioscin (PD), MP and pseudoprotodioscin (PPD) on the synthesis-related gene expression of cholesterol and triglycerides. MTT assay apoptosis assay with annexin AV-APC and 7-AAD double staining were performed. MicroRNA assay and qRT-PCR were used to analyze the gene expression which regulates synthesis of cholesterol and triglycerides. Western blot was to demonstrate the levels of target proteins. Cholesterol efflux assay was executed to study the stimulative effect of saponins on cholesterol efflux. In Hep G2 cells, PPD increased ABCA1 protein and mRNA levels, and promoted the effluxion of ApoA-1-mediated cholesterol. The underlying mechanisms involved that PPD inhibited SREBP1c and SREBP2 transcription by decreasing microRNA 33a/b levels. This procedure reciprocally led to the increase of ABCA1 levels. In THP-1 macrophages, PPD showed the similar effect, which reduced HMGCR, FAS and ACC mRNA levels and promoted low density lipoprotein receptor by decreasing the PCSK9 levels. These studies demonstrated that PPD is a potential agent for cholesterol efflux, SREBPs and microRNA 33a/b inhibition, which related to the gene expression for the synthesis of cholesterol and triglycerides.

A lipid-free and insulin-supplemented medium supports De Novo fatty acid synthesis gene activation in melanoma cells.

While investigating the role played by de novo lipid (DNL) biosynthesis in cancer cells, we sought a medium condition that would support cell proliferation without providing any serum lipids. Here we report that a defined serum free cell culture medium condition containing insulin, transferrin and selenium (ITS) supports controlled study of transcriptional regulation of de novo fatty acid (DNFA) production and de novo cholesterol synthesis (DNCS) in melanoma cell lines. This lipid-free ITS medium is able to support continuous proliferation of several melanoma cell lines that utilize DNL to support their lipid requirements. We show that the ITS medium stimulates gene transcription in support of both DNFA and DNCS, specifically mediated by SREBP1/2 in melanoma cells. We further found that the ITS medium promoted SREBP1 nuclear localization and occupancy on DNFA gene promoters. Our data show clear utility of this serum and lipid-free medium for melanoma cancer cell culture and lipid-related areas of investigation.

Yarrow supercritical extract exerts antitumoral properties by targeting lipid metabolism in pancreatic cancer.

Metabolic reprogramming is considered a hallmark of cancer. Currently, the altered lipid metabolism in cancer is a topic of interest due to the prominent role of lipids regulating the progression of various types of tumors. Lipids and lipid-derived molecules have been shown to activate growth regulatory pathways and to promote malignancy in pancreatic cancer. In a previous work, we have described the antitumoral properties of Yarrow (Achillea Millefolium) CO2 supercritical extract (Yarrow SFE) in pancreatic cancer. Herein, we aim to investigate the underlaying molecular mechanisms by which Yarrow SFE induces cytotoxicity in pancreatic cancer cells. Yarrow SFE downregulates SREBF1 and downstream molecular targets of this transcription factor, such as fatty acid synthase (FASN) and stearoyl-CoA desaturase (SCD). Importantly, we demonstrate the in vivo effect of Yarrow SFE diminishing the tumor growth in a xenograft mouse model of pancreatic cancer. Our data suggest that Yarrow SFE can be proposed as a complementary adjuvant or nutritional supplement in pancreatic cancer therapy.

Adding a purple corn extract in rats supplemented with chia oil decreases gene expression of SREBP-1c and retains Δ5 and Δ6 hepatic desaturase activity, unmodified the hepatic lipid profile.

Flavonoids upregulate gene expression of PPAR-α and underregulate the gene expression of SREBP-1c, and their intake increases the plasmatic concentration of n-3 LC-PUFAs. However, the biological mechanisms underlying these effects have not been elucidated. In this work, the effect of oral supplementation of ALA from chia (Salvia hispanica L.) seed oil and anthocyanins from a purple corn extract (PCE) on gene expression of SREBP-1c, PPAR-α and Δ5 and Δ6 desaturases (Δ5D and Δ6D), the activity of these enzymes in the liver as well as the hepatic lipid profile were evaluated in thirty-six female Sprague Dawley rats whose diet was supplemented with olive oil (OL), chia oil (CH), olive oil and PCE (OL + PCE) or chia oil and PCE (CH + PCE). Gene expression of PPAR-α was significantly higher when supplemented with CH and CH + PCE, SREBP-1c gene expression was higher when supplemented with chia oil. CH supplementation enhanced Δ5D expression whereas no significant differences between treatments were observed concerning Δ6D gene expression. Activities of both desaturases were increased by including olive oil (OL + PCE and OL), and they were found to be higher in CH + PCE respect to CH for both enzymes. The ALA and n-3 LCPUFAs hepatic content was higher with CH, decreasing the levels of AA and n-6 LCPUFAs. It is concluded that the joint action of flavonoids such as anthocyanins and ALA show an anti-adipogenic effect. Desaturase activity was inhibited by ALA and kept by the anthocyanins from PCE, thus anthocyanins would exert a protective effect on the desaturase activity but they would not affect on its gene expression, however, high doses of ALA increased the production of its metabolites, masking the effect of PCE.

Fermented Soymilk Alleviates Lipid Accumulation by Inhibition of SREBP-1 and Activation of NRF-2 in the Hepatocellular Steatosis Model.

Ingredients of soy and fermented soy products have been widely utilized as food supplements for health-enhancing properties. The aim of this study was to evaluate the effects of fermented soymilk (FSM) and soymilk (SM) on free fatty acid-induced lipogenesis in the hepatocellular steatosis model. HepG2 cells were incubated with palmitic acid (PA) for 24 h to induce lipogenesis and accumulation of intracellular lipid contents. The PA-treated cells were co-incubated with FSM, SM, genistein, and estrogen, respectively. Lipid accumulation in the PA-treated HpG2 cells was significantly decreased by co-incubation with FSM. Treatment of HepG2 cells with PA combined with genistein or estrogen significantly increased the expression of SREBP-1. However, FSM co-incubation significantly attenuated SREBP-1 expression in the PA-treated HepG2 cells; in addition, expression of NRF-2 and phosphorylation of ERK were significantly increased in the PA and FSM co-incubated cells. PA-induced ROS production was significantly reduced by FSM and SM. Our results suggested that the bioactive components of FSM could protect hepatocytes against the lipid accumulation and ROS production induced by free fatty acids. These effects may be mediated by the inhibition of SREBP-1 and the activation of NRF-2 via the ERK pathway in HepG2 cells.

Glu-Phe from onion (Allium Cepa L.) attenuates lipogenesis in hepatocytes.

A Glu-Phe (EF) was isolated from onion (Allium cepa L. cv. Sunpower). The chemical structure of EF was determined by nuclear magnetic resonance and electrospray ionization-mass (ESI-MS) spectroscopy. We showed that EF reduced lipid accumulation in mouse hepatocytes by inhibiting the expression of sterol regulatory element-binding protein-1c (SREBP-1c) and its lipogenic target genes. We also found that AMP-activated protein kinase (AMPK) was required for the inhibitory effect of EF on lipid accumulation in mouse hepatocytes. Furthermore, EF was qualified in nine onion cultivars by selective multiple reaction-monitoring detection of liquid chromatography-ESI-MS. These results suggest that EF could contribute to the beneficial effect of onion supplement in maintaining hepatic lipid homeostasis.

Chokeberry attenuates the expression of genes related to de novo lipogenesis in the hepatocytes of mice with nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD), which is characterized by steatosis, is a major public health concern. Previous studies have shown that chokeberry has anti-inflammatory, antimutagenic, hepatoprotective, cardioprotective, and antidiabetic effects. In this study, we hypothesized that chokeberry powder can attenuate the expression of genes related to de novo lipogenesis and the triglyceride levels in the hepatocytes of mice with high-fat diet-induced NAFLD. After coadministering chokeberry powder for 8weeks (0.5% and 1% powder) with a high-fat diet, mice that consumed chokeberry powder diets, regardless of the dose, had significantly lower liver triglyceride levels than control mice that were fed a high-fat diet (P=.0145 and P<.0012, respectively). Compared with mice that were fed a high-fat diet, mice that were given 1% chokeberry powder exhibited significantly decreased mRNA expression of sterol regulatory element-binding protein (P=.009) and acetyl-CoA carboxylase (P=.0032) in the liver. Compared with mice in the control group, fatty acid synthase (FAS) expression significantly increased in the mice that were fed a high-fat diet, but both chokeberry powder-treated groups had significantly decreased FAS expression (P=.0157 and P<.0001, respectively). The size of the fat droplets was decreased in the livers of the chokeberry-supplemented groups. In summary, the administration of chokeberry powder may help attenuate high-fat diet-induced NAFLD by regulating the expression levels of sterol regulatory element-binding protein, acetyl-CoA carboxylase, and FAS and by decreasing the size of the fat droplets in the liver.

Citrulline and Nonessential Amino Acids Prevent Fructose-Induced Nonalcoholic Fatty Liver Disease in Rats.

BACKGROUND: Fructose induces nonalcoholic fatty liver disease (NAFLD). Citrulline (Cit) may exert a beneficial effect on steatosis. OBJECTIVE: We compared the effects of Cit and an isonitrogenous mixture of nonessential amino acids (NEAAs) on fructose-induced NAFLD. METHODS: Twenty-two male Sprague Dawley rats were randomly assigned into 4 groups (n = 4-6) to receive for 8 wk a 60% fructose diet, either alone or supplemented with Cit (1 g · kg(-1) · d(-1)), or an isonitrogenous amount of NEAAs, or the same NEAA-supplemented diet with starch and maltodextrin instead of fructose (controls). Nutritional and metabolic status, liver function, and expression of genes of hepatic lipid metabolism were determined. RESULTS: Compared with controls, fructose led to NAFLD with significantly higher visceral fat mass (128%), lower lean body mass (-7%), insulin resistance (135%), increased plasma triglycerides (TGs; 67%), and altered plasma amino acid concentrations with decreased Arg bioavailability (-27%). This was corrected by both NEAA and Cit supplementation. Fructose caused a 2-fold increase in the gene expression of fatty acid synthase (Fas) and 70% and 90% decreases in that of carnitine palmitoyl-transferase 1a and microsomal TG transfer protein via a nearly 10-fold higher gene expression of sterol regulatory element-binding protein-1c (Srebp1c) and carbohydrate-responsive element-binding protein (Chrebp), and a 90% lower gene expression of peroxisome proliferator-activated receptor α (Ppara). NEAA or Cit supplementation led to a Ppara gene expression similar to controls and decreased those of Srebp1c and Chrebp in the liver by 50-60%. Only Cit led to Fas gene expression and Arg bioavailability similar to controls. CONCLUSION: In our rat model, Cit and NEAAs effectively prevented fructose-induced NAFLD. On the basis of literature data and our findings, we propose that NEAAs may exert their effects specifically on the liver, whereas Cit presumably acts at both the hepatic and whole-body level, in part via improved peripheral Arg metabolism.

Activation of hepatic CREBH and Insig signaling in the anti-hypertriglyceridemic mechanism of R-α-lipoic acid.

The activation of sterol regulatory element binding proteins (SREBPs) is regulated by insulin-induced genes 1 and 2 (Insig-1 and Insig-2) and SCAP. We previously reported that feeding R-α-lipoic acid (LA) to Zucker diabetic fatty (ZDF) rats improves severe hypertriglyceridemia. In this study, we investigated the role of cyclic AMP-responsive element binding protein H (CREBH) in the lipid-lowering mechanism of LA and its involvement in the SREBP-1c and Insig pathway. Incubation of McA cells with LA (0.2 mM) or glucose (6 mM) stimulated activation of CREBH. LA treatment further induced mRNA expression of Insig-1 and Insig-2a, but not Insig-2b, in glucose-treated cells. In vivo, feeding LA to obesity-induced hyperlipidemic ZDF rats activated hepatic CREBH and stimulated transcription and translation of Insig-1 and Insig-2a. Activation of CREBH and Insigs induced by LA suppressed processing of SREBP-1c precursor into nuclear SREBP-1c, which subsequently inhibited expression of genes involved in fatty acid synthesis, including FASN, ACC and SCD-1, and reduced triglyceride (TG) contents in both glucose-treated cells and ZDF rat livers. Additionally, LA treatment also decreased abundances of very low density lipoprotein (VLDL)-associated apolipoproteins, apoB100 and apoE, in glucose-treated cells and livers of ZDF rats, leading to decreased secretion of VLDL and improvement of hypertriglyceridemia. This study unveils a novel molecular mechanism whereby LA lowers TG via activation of hepatic CREBH and increased expression of Insig-1 and Insig-2a to inhibit de novo lipogenesis and VLDL secretion. These findings provide novel insight into the therapeutic potential of LA as an anti-hypertriglyceridemia dietary molecule.

Maternal taurine supplementation attenuates maternal fructose-induced metabolic and inflammatory dysregulation and partially reverses adverse metabolic programming in offspring.

Excessive fructose consumption is associated with insulin resistance (IR) and nonalcoholic fatty liver disease (NAFLD), and high fructose intake during pregnancy can lead to compromised fetal development in the rat. Evidence suggests that the amino acid taurine can ameliorate fructose-induced IR and NAFLD in nonpregnant animals. This study investigated the efficacy of taurine supplementation on maternal fructose-induced metabolic dysfunction and neonatal health. Time-mated Wistar rats were randomized to four groups during pregnancy and lactation: (a) control diet (CON), (b) CON supplemented with 1.5% taurine in drinking water (CT), (c) CON supplemented with fructose solution (F) and (d) F supplemented with taurine (FT). Maternal and neonatal weights, plasma cytokines and hepatic gene expression were analyzed. Maternal hyperinsulinemia, increased homeostasis model assessment of IR indices and elevated proinflammatory cytokines were observed in F group and normalized in FT group. Maternal fructose-induced hepatic steatosis accompanied with increased liver weight was ameliorated with taurine supplementation. Maternal hepatic sterol regulatory element-binding protein-1c and fatty acid synthase expression was significantly increased in the F group compared to the CON, CT and FT groups. Neonatal hepatic phosphoenolpyruvate carboxykinase expression was increased in male F neonates compared to the CON, CT and FT groups and was increased in female F and FT neonates compared to CON and CT. Interleukin-1ß expression was decreased in male CT and FT neonates compared to other male groups. Hepatic tumour necrosis factor receptor-1 was lower in the male FT group than the F group. These results demonstrate that maternal taurine supplementation can partially reverse fructose-induced maternal metabolic dysfunction and may ameliorate adverse developmental programming effects in offspring in a sex-specific manner.

Crude extracts from Lycium barbarum suppress SREBP-1c expression and prevent diet-induced fatty liver through AMPK activation.

Lycium barbarum polysaccharide (LBP) is well known in traditional Chinese herbal medicine that, has beneficial effects. Previous study reported that LBP reduced blood glucose and serum lipids. However, the underlying LBP-regulating mechanisms remain largely unknown. The main purpose of this study was to investigate whether LBP prevented fatty liver through activation of adenosine monophosphate-activated protein kinase (AMPK) and suppression of sterol regulatory element-binding protein-1c (SREBP-1c). Male C57BL/6J mice were fed a low-fat diet, high-fat diet, or 100 mg/kg LBP-treatment diet for 24 weeks. HepG2 cells were treated with LBP in the presence of palmitic acid. In our study, LBP can improve body compositions and lipid metabolic profiles in high-fat diet-fed mice. Oil Red O staining in vivo and in vitro showed that LBP significantly reduced hepatic intracellular triacylglycerol accumulation. H&E staining also showed that LBP can attenuate liver steatosis. Hepatic genes expression profiles demonstrated that LBP can activate the phosphorylation of AMPK, suppress nuclear expression of SREBP-1c, and decrease protein and mRNA expression of lipogenic genes in vivo or in vitro. Moreover, LBP significantly elevated uncoupling protein-1 (UCP1) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) expression of brown adipose tissue. In summary, LBP possesses a potential novel treatment in preventing diet-induced fatty liver.

Oxymatrine attenuates hepatic steatosis in non-alcoholic fatty liver disease rats fed with high fructose diet through inhibition of sterol regulatory element binding transcription factor 1 (Srebf1) and activation of peroxisome proliferator activated receptor alpha (Pparα).

The aim of this study was to examine the therapeutic effect of oxymatrine, a monomer isolated from the medicinal plant Sophora flavescens Ait, on the hepatic lipid metabolism in non-alcoholic fatty liver (NAFLD) rats and to explore the potential mechanism. Rats were fed with high fructose diet for 8 weeks to establish the NAFLD model, then were given oxymatrine treatment (40, 80, and 160 mg/kg, respectively) for another 8 weeks. Body weight gain, liver index, serum and liver lipids, and histopathological evaluation were measured. Enzymatic activity and gene expression of the key enzymes involved in the lipogenesis and fatty acid oxidation were assayed. The results showed that oxymatrine treatment reduced body weight gain, liver weight, liver index, dyslipidemia, and liver triglyceride level in a dose dependant manner. Importantly, the histopathological examination of liver confirmed that oxymatrine could decrease the liver lipid accumulation. The treatment also decreased the fatty acid synthase (FAS) enzymatic activity and increased the carnitine palmitoyltransferase 1A (CPT1A) enzymatic activity. Besides, oxymatrine treatment decreased the mRNA expression of sterol regulatory element binding transcription factor 1(Srebf1), fatty acid synthase (Fasn), and acetyl CoA carboxylase (Acc), and increased the mRNA expression of peroxisome proliferator activated receptor alpha (Pparα), carnitine palmitoyltransferase 1A (Cpt1a), and acyl CoA oxidase (Acox1) in high fructose diet induced NAFLD rats. These results suggested that the therapeutic effect of oxymatrine on the hepatic steatosis in high fructose diet induced fatty liver rats is partly due to down-regulating Srebf1 and up-regulating Pparα mediated metabolic pathways simultaneously.

The hypotriglyceridemic effect of biotin supplementation involves increased levels of cGMP and AMPK activation.

In addition to its role as a carboxylase cofactor, biotin modifies gene expression and has manifold effects on systemic processes. Several studies have shown that biotin supplementation reduces hypertriglyceridemia. We have previously reported that this effect is related to decreased expression of lipogenic genes. In the present work, we analyzed signaling pathways and posttranscriptional mechanisms involved in the hypotriglyceridemic effects of biotin. Male BALB/cAnN Hsd mice were fed a control or a biotin-supplemented diet (1.76 or 97.7 mg of free biotin/kg diet, respectively for 8 weeks after weaning. The abundance of mature sterol regulatory element-binding protein (SREBP-1c), fatty-acid synthase (FAS), total acetyl-CoA carboxylase-1 (ACC-1) and its phosphorylated form, and AMP-activated protein kinase (AMPK) were evaluated in the liver. We also determined the serum triglyceride concentrations and the hepatic levels of triglycerides and cyclic GMP (cGMP). Compared to the control group, biotin-supplemented mice had lower serum and hepatic triglyceride concentrations. Biotin supplementation increased the levels of cGMP and the phosphorylated forms of AMPK and ACC-1 and decreased the abundance of the mature form of SREBP-1c and FAS. These data provide evidence that the mechanisms by which biotin supplementation reduces lipogenesis involve increased cGMP content and AMPK activation. In turn, these changes lead to augmented ACC-1 phosphorylation and decreased expression of both the mature form of SREBP-1c and FAS. Our results demonstrate for the first time that AMPK is involved in the effects of biotin supplementation and offer new insights into the mechanisms of biotin-mediated hypotriglyceridemic effects.

Melissa officinalis essential oil reduces plasma triglycerides in human apolipoprotein E2 transgenic mice by inhibiting sterol regulatory element-binding protein-1c-dependent fatty acid synthesis.

We investigated the hypolipidemic effects of Melissa officinalis essential oil (MOEO) in human APOE2 transgenic mice and lipid-loaded HepG2 cells. Plasma TG concentrations were significantly less in APOE2 mice orally administered MOEO (12.5 µg/d) for 2 wk than in the vehicle-treated group. Cellular TG and cholesterol concentrations were also significantly decreased in a dose- (400 and 800 mg/L) and time- (12 and 24 h) dependent manner in HepG2 cells stimulated with MOEO compared with controls. Mouse hepatic transcriptome analysis suggested MOEO feeding altered several lipid metabolic pathways, including bile acid and cholesterol synthesis and fatty acid metabolism. In HepG2 cells, the rate of fatty acid oxidation, as assessed using [1-(14)C]palmitate, was unaltered; however, the rate of fatty acid synthesis quantified with [1-(14)C]acetate was significantly reduced by treatment with 400 and 800 mg/L MOEO compared with untreated controls. This reduction was due to the decreased expression of SREBP-1c and its responsive genes in fatty acid synthesis, including FAS, SCD1, and ACC1. Subsequent chromatin immunoprecipitation analysis further demonstrated that the binding of p300/CBP-associated factor, a coactivator of SREBP-1c, and histone H3 lysine 14 acetylation at the FAS, SCD1, and ACC1 promoters were significantly reduced in the livers of APOE2 mice and HepG2 cells treated with MOEO compared with their controls. Additionally, MOEO stimulation in HepG2 cells induced bile acid synthesis and reduced the nuclear form of SREBP-2, a key transcription factor in hepatic cholesterol synthesis. These findings suggest that the intake of phytochemicals with pleasant scent could have beneficial metabolic effects.

Gentiana manshurica Kitagawa reverses acute alcohol-induced liver steatosis through blocking sterol regulatory element-binding protein-1 maturation.

This study was undertaken to investigate the protective effects of Gentiana manshurica Kitagawa (GM) on acute alcohol-induced fatty liver. Mice were treated with ethanol (5 g/kg of body weight) by gavage every 12 h for a total of three doses to induce acute fatty liver. Methanol extract of GM (50, 100, or 200 mg/kg) or silymarin (100 mg/kg) was gavaged simultaneously with ethanol for three doses. GM administration significantly reduced the increases in serum ALT and AST levels, the serum and hepatic triglyceride levels, at 4 h after the last ethanol administration. GM was also found to prevent ethanol-induced hepatic steatosis and necrosis, as indicated by liver histopathological studies. Additionally, GM suppressed the elevation of malondialdehyde (MDA) levels, restored the glutathione (GSH) levels, and enhanced the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. The concurrent administration of GM efficaciously abrogated cytochrome P450 2E1 (CYP2E1) induction. Moreover, GM significantly reduced the nuclear translocation of sterol regulatory element-binding protein-1 (nSREBP-1) in ethanol-treated mice. These data indicated that GM possessed the ability to prevent ethanol-induced acute liver steatosis, possibly through blocking CYP2E1-mediated free radical scavenging effects and SREBP-1-regulated fatty acid synthesis. Especially, GM may be developed as a potential therapeutic candidate for ethanol-induced oxidative damage in liver.

Eicosapentaenoic acid improves hepatic steatosis independent of PPARα activation through inhibition of SREBP-1 maturation in mice.

Eicosapentaenoic acid (EPA) in fish oil is known to improve hepatic steatosis. However, it remains unclear whether such action of EPA is actually caused by peroxisome proliferator-activated receptor α (PPARα) activation. To explore the contribution of PPARα to the effects of EPA itself, male wild-type and Ppara-null mice were fed a saturated fat diet for 16 weeks, and highly (>98%)-purified EPA was administered in the last 12 weeks. Furthermore, the changes caused by EPA treatment were compared to those elicited by fenofibrate (FF), a typical PPARα activator. A saturated fat diet caused macrovesicular steatosis in both genotypes. However, EPA ameliorated steatosis only in wild-type mice without PPARα activation, which was evidently different from numerous previous observations. Instead, EPA inhibited maturation of sterol-responsive element-binding protein (SREBP)-1 in the presence of PPARα through down-regulation of SREBP cleavage-activating protein and site-1 protease. Additionally, EPA suppressed fatty acid uptake and promoted hydrolysis of intrahepatic triglycerides in a PPARα-independent manner. These effects were distinct from those of fenofibrate. Although fenofibrate induced NAPDH oxidase and acyl-coenzyme A oxidase and significantly increased hepatic lipid peroxides, EPA caused PPARα-dependent induction of superoxide dismutases, probably contributing to a decrease in the lipid peroxides. These results firstly demonstrate detailed mechanisms of steatosis-ameliorating effects of EPA without PPARα activation and ensuing augmentation of hepatic oxidative stress.

Magnolia officinalis reverses alcoholic fatty liver by inhibiting the maturation of sterol regulatory element-binding protein-1c.

The generally accepted hypothesis for the pathogenesis of alcoholic liver disease (ALD) is the two-hit model, which proposes that fat accumulation in the liver increases the sensitivity of the liver to a second hit that leads to inflammatory liver cell damage. In this study we evaluated the effects of Magnolia officinalis (MO), which contains honokiol and magnolol as the primary pharmacological components, to eradicate fatty liver in rats fed an ethanol diet. In vitro studies showed that MO was able to protect RAW 264.7 cells from ethanol-induced production of tumor necrosis factor-alpha, reactive oxygen species, and superoxide anion radicals; the activation of NADPH oxidase; and subsequent cell death. We also investigated the therapeutic effects of MO on alcoholic fatty liver in Lieber-DeCarli ethanol diet-fed rats. MO treatment of the rats for the last 2 weeks of ethanol feeding completely reversed all the serum, hepatic parameters, and fatty liver changes. The increased maturation of sterol regulatory element-binding protein-1c in the liver by ethanol treatment was completely inhibited by treatment with MO. Therefore, MO may be a promising candidate for development as a therapeutic agent for ALD.

Prevention of steatohepatitis by pioglitazone: implication of adiponectin-dependent inhibition of SREBP-1c and inflammation.

BACKGROUND/AIMS: Peroxisome proliferator-activated receptor gamma (PPARgamma) agonist drugs, like pioglitazone (PGZ), are proposed as treatments for steatohepatitis. Their mechanisms of action remain ill-clarified. METHODS: To test the hypothesis that PGZ improves steatohepatitis through adiponectin-dependent stimulation of AMPK and/or PPARalpha, mice lacking adiponectin (Adipo(-/-)) or the AMPKalpha1 catalytic subunit (AMPKalpha1(-/-)) or wild-type (Wt) mice were fed the methionine and choline deficient (MCD) diet, supplemented or not with PGZ. RESULTS: In Wt mice, PGZ increased circulating levels of adiponectin and reduced the severity of MCD-induced steatohepatitis but there was no evidence of activation of AMPK or PPARalpha and their downstream targets. By contrast, PGZ completely repressed nuclear translocation of SREBP-1c, a key transcription factor for de novo lipogenesis. This effect was lacking in Adipo(-/-) mice in which PGZ failed to prevent steatohepatitis. Surprisingly, AMPKalpha1(-/-) mice were resistant to MCD-induced steatohepatitis, a status also associated with repression of SREBP-1c. CONCLUSIONS: The preventive effect of PGZ on MCD-induced steatohepatitis depends on adiponectin upregulation but apparently does not involve AMPK or PPARalpha activation. The inhibition of SREBP-1c and dependent repression of lipogenesis are likely to participate in this effect. The mechanisms by which PGZ and adiponectin control SREBP-1c and inflammation remain to be elucidated.