Hypolipidemic Effect and Mechanism of Palmatine from Coptis chinensis in Hamsters Fed High‐Fat diet

Palmatine (PAL) is one of the main alkaloids in Coptis chinensis. The present aim was to investigate the hypolipidemic effect and mechanism of palmatine in hamsters fed with high‐fat diet (HFD). PAL treatment decreased serum total cholesterol (TC), triglyceride (TG), and low‐density lipoprotein cholesterol (LDL‐C) levels, as well as increased fecal excretion of TC and total bile acids (TBA) in hyperlipidemic hamsters. Furthermore, PAL treatment up‐regulated low‐density lipoprotein receptor (LDLR) and cholesterol 7α‐hydroxylase (CYP7A1) mRNA and protein expression and down‐regulated apical sodium‐dependent bile salt transporter (ASBT) mRNA and protein expression. These results demonstrated that PAL as a potential natural cholesterol lowering agent works by up‐regulating LDLR and CYP7A1 mRNA and protein expression, down‐regulating ASBT mRNA and protein expression, as well as enhancing fecal excretion of TC and TBA. The findings in our study suggest that palmatine could be a potential natural agent for treating hyperlipidemia. Copyright © 2015 John Wiley & Sons, Ltd.     

Hypolipidemic Activity of Okra is Mediated Through Inhibition of Lipogenesis and Upregulation of Cholesterol Degradation

Little is known about the hypolipidemic activity of okra; therefore, we investigated the hypolipidemic activity of okra and its interaction with gene expression of several key components involved in lipid homeostasis. Male C57BL/6 mice were randomly divided into three groups and fed with hyperlipidemic diet or two hyperlipidemic diets supplemented with 1% or 2% okra powder for eight weeks. Results demonstrated that okra dose‐dependently decreased serum and hepatic total cholesterol and triglyceride, and enhanced fecal excretion of bile acids. Gene expression analysis revealed that okra upregulated cholesterol 7α‐hydroxylase (CYP7A1) expression, downregulated expression of sterol regulatory element‐binding protein 1c (SREBP1c) and fatty acid synthase (FAS), with no effect on sterol regulatory element‐binding protein 2 (SREBP2), 3‐hydroxy‐3‐methylglutaryl‐CoA reductase (HMGR), low‐density lipoprotein receptor (LDLR) and carnitine palmitoyltransferase‐1A (CPT1A). It was suggested that hypolipidemic activity of okra was mediated most likely by upregulation of cholesterol degradation through CYP7A1 and by inhibition of lipogenesis through SREBP1c and FAS. Okra raw and fractionated polysaccharide showed strong bile acid binding capacity in vitro, which may contribute to the hypolipidemic activity observed. In conclusion, okra has potential application in the management of hyperlipidemia and its associated metabolic disorders. Copyright © 2013 John Wiley & Sons, Ltd.     

Berberine inhibits SREBP‐1‐related clozapine and risperidone induced adipogenesis in 3T3‐L1 cells

Weight gain is a common and potentially serious complication associated with the treatment of second generation antipsychotics such as clozapine and risperidone. Increased peripheral adipogenesis via the SREBP‐1 pathway could be one critical mechanism responsible for antipsychotic drug‐induced weight gain. Berberine, a botanic alkaloid, has been shown in our previous studies to inhibit adipogenesis in cell and animal models. MTT was used to determine the cytotoxic effects of clozapine and risperidone in combination with berberine. Differentiation of 3T3‐L1 cells was monitored by Oil‐Red‐O staining and the expression of SREBP‐1 and related proteins was determined by real‐time RT‐PCR and western blotting. The results showed that neither clozapine nor risperidone, alone or in combination with berberine had significant effects on cell viability. Eight days treatment with 15 μm clozapine increased adipogenesis by 37.4% and 50 μm risperidone increased adipogenesis by 26.5% during 3T3‐L1 cell differentiation accompanied by increased SREBP‐1, PPARγ, C/EBPα, LDLR and Adiponectin gene expression. More importantly, the addition of 8 μm berberine diminished the induction of adipogenesis almost completely accompanied by down‐regulated mRNA and protein expression levels of SREBP‐1‐related proteins. These encouraging results may lead to the use of berberine as an adjuvant to prevent weight gain during second generation antipsychotic medication. Copyright © 2010 John Wiley & Sons, Ltd.     

Quercetin inhibits α-MSH-stimulated melanogenesis in B16F10 melanoma cells

Quercetin is known to inhibit tyrosinase activity and melanin production in melanocytes. However, several reports suggest that quercetin has different and opposite effects on melanogenesis. This study examined the precise effects of quercetin on melanogenesis using cell‐free assay systems and melanocytes. Quercetin inhibited the monophenolase and diphenolase activities of tyrosinase, and melanin synthesis in cell‐free assay systems. Quercetin induced mild stimulation of the tyrosinase activity and dihydroxyphenylalaminechrome tautomerase (TRP‐2) expression but only at low concentrations (<20 μm ) in B16F10 melanoma cells. In contrast, the addition of 50 μm quercetin to the cells led to a significant decrease in the activity and synthesis of tyrosinase, as well as a decrease in the expression of tyrosinase‐related protein‐1 and TRP‐2 proteins, regardless of the presence or absence of α‐melanocyte stimulating hormone (α‐MSH). Quercetin also reduced the intracellular cAMP and the phosphorylated protein kinase A levels in α‐MSH‐stimulated B16F10 cells. Moreover, quercetin (20 μm ) diminished the expression and activity of tyrosinase, and melanin content in cultured normal human epidermal melanocytes. These effects were not related to its cytotoxic action. Although the in vivo effects of quercetin are still unclear, these results suggest that quercetin could play important roles in controlling melanogenesis. Copyright © 2011 John Wiley & Sons, Ltd.     

冠心康通过miRNA干预HepG2细胞胆固醇代谢的研究

  目的：研究冠心康对不同浓度氧化低密度脂蛋白(ox-LDL)诱导HepG2细胞后胆固醇水平及胆固醇代谢相关miR-33a、miR-122以及低密度脂蛋白受体(LDLR)的影响。  方法：制备冠心康和辛伐他汀含药血清,将HepG2细胞随机分为空白对照组、模型组、辛伐他汀组和冠心康组,分别用20、40、80、160 mg/L浓度的ox-LDL诱导HepG2细胞24 h后,再用各组含药血清孵育48 h。采用油红O染色法观察HepG2胆固醇代谢模型的细胞形态,实时荧光定量PCR法检测miR-33a、miR-122、LDLR基因表达水平,Western blot法检测LDLR蛋白表达。  结果：与模型组比较,冠心康可显著减少不同浓度ox-LDL诱导后HepG2细胞中橙色脂滴含量,上调ox-LDL诱导后细胞中LDLR基因和蛋白的表达,并抑制miR-33a和miR-122的表达(P<0.05,P<0.01)。  结论：冠心康可通过上调LDLR基因和蛋白的表达,抑制miR-33a和miR-122的表达,从而降低细胞中胆固醇含量,缓解胆固醇代谢失衡进程。     

Hovenia Dulcis Extract Reduces Lipid Accumulation in Oleic Acid‐Induced Steatosis of Hep G2 Cells via Activation of AMPK and PPARα/CPT‐1 Pathway and in Acute Hyperlipidemia Mouse Model

Hovenia dulcis Thunb. (HDT) was known to have anti‐fatigue, anti‐diabetes, neuroprotective, and hepatoprotective effects. In the present study, the anti‐fatty liver mechanism of HDT was elucidated in oleic acid (OA)‐treated Hep G2 cells and acute hyperlipidemia mouse model using Triton WR‐1339. Here, HDT activated p‐AMP‐activated protein kinase (p‐AMPK), proliferator activated receptor‐α, carnitine palmitoyltransferase and also inhibited the expression of lipogenesis and cholesterol synthesis proteins, such as 3‐hydroxy‐3‐methylglutaryl‐CoA reductase, sterol regulatory element binding protein‐1c, SREBP‐2, and fatty acid synthase in OA‐treated Hep G2 cells. Conversely, AMPK inhibitor compound C blocked the anti‐fatty liver effect of HDT to induce AMPK phosphorylation and decrease 3‐hydroxy‐3‐methylglutaryl‐CoA reductase and lipid accumulation by oil red O staining in OA‐treated Hep G2 cells. Additionally, HDT pretreatment protected against the increase of serum total cholesterol, triglyceride, low‐density lipoprotein cholesterol and phospholipid in an acute hyperlipidemia mouse model with enhancement of glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase activities. Taken together, HDT inhibits OA‐induced hepatic lipid accumulation via activation of AMPK and proliferator activated receptor‐α/carnitine palmitoyltransferase signaling and enhancement of antioxidant activity as a potent candidate for nonalcoholic fatty liver disease and hyperlipidemia. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of crocin and saffron aqueous extract on gene expression of SIRT1, AMPK,LOX1, NF‐κB,and MCP‐1 in patients with coronary artery disease: A randomized placebo‐controlled clinical trial

This trial evaluated the potential impacts of saffron aqueous extract (SAE) and its main carotenoid on some of the atherosclerosis‐related gene expression and serum levels of oxidized low‐density cholesterol (ox‐LDL) and Monocyte chemoattractant protein 1 (MCP‐1) in patients with coronary artery disease (CAD). Participants of this randomized controlled trial included 84 CAD patients who categorized into three groups: Group 1 received crocin (30 mg/day), Group 2 SAE (30 mg/day), and Group 3 placebo for 8 weeks. Gene expression of Sirtuin 1 (SIRT1), 5'‐adenosine monophosphate‐activated protein kinase (AMPK), Lectin‐like oxidized LDL receptor 1 (LOX1), nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB), and MCP‐1 in peripheral blood mononuclear cells assessed by real‐time PCR. Furthermore, serum ox‐LDL and MCP‐1 levels measured at the beginning and end of the intervention. Compared with the placebo group, gene expression of SIRT1 and AMPK increased significantly in the crocin group (p = .001), and the expression of LOX1 and NF‐κB decreased significantly (p = .016 and .004, respectively). Serum ox‐LDL levels decreased significantly in the crocin group after the intervention (p = .002) while MCP‐1 levels decreased both in crocin and SAE groups (p = .001). Crocin may have beneficial effects on CAD patients by increasing the gene expression of SIRT1 and AMPK and decreasing the expression of LOX1 and NF‐κB.     

小檗碱降脂作用机制研究概况

现代研究发现小檗碱(berberine,BBR)有明确的降脂作用,且不良反应极小。查阅近年相关文献,发现BBR的降脂机制是多方面的,可通过调节脂代谢过程中相关酶的活性、基因表达,如活化AMP蛋白激酶;提高LDLR、Insig-2、ABCA1基因表达水平;抑制PCSK9转录;抑制ACAT2、PPARγ表达等下调血脂水平。现从脂质吸收、合成、转运、清除等角度对BBR的降脂作用机制进行概括总结,以期为BBR治疗脂血症相关疾病提供一定的科学依据。参考文献24篇。     

Effects of Sinensetin on Lipid Metabolism in Mature 3T3‐L1 Adipocytes

Sinensetin is a rare polymethoxylated flavone found in certain citrus fruits. In this study, we investigated the effects of sinensetin on lipid metabolism in mature 3T3‐L1 adipocytes. Sinensetin decreased the expression of sterol regulatory element‐binding protein 1c (SREBP1c), suggesting its antiadipogeneic property via downreguation of SREBP1c. Also, sinensetin increased the phosphorylation of protein kinase A and hormone‐sensitive lipase, indicating its lipolytic property via a cAMP‐mediated signaling pathway. Moreover, sinensetin inhibited insulin‐stimulated glucose uptake by decreasing the phosphorylation of insulin receptor substrate and Akt. Furthermore, sinensetin increased the phosphorylation of AMP‐activated protein kinase (AMPK) and acetyl‐CoA carboxylase. It also upregulated mRNA expression of carnitine palmitoyltransferase‐1a, suggesting that sinensetin enhances fatty acid β‐oxidation through the AMPK pathway. Taken together, these results suggest that sinensetin may have potential as a natural agent for prevention/improvement of obesity. Copyright © 2012 John Wiley & Sons, Ltd.     

黄连碱对胆固醇代谢关键基因的调节作用

该文主要研究胆固醇和25-羟胆固醇诱导对HepG2细胞胆固醇代谢的影响和黄连中黄连碱的降胆固醇活性及调节机制.用生化法检测了总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白-胆固醇(LDL-c)和高密度脂蛋白-胆固醇(HDL-c)水平;用qRT-PCR和Western bolt技术检测了胆固醇代谢关键基因LDLR,HMGCR,CYP7A1 mRNA和蛋白的表达水平.结果显示胆固醇和25-羟基胆固醇诱导能导致LDLR,CYP7A1的mRNA和蛋白的表达下降从而使TC和LDL-c含量上升.黄连碱能上调LDLR和CYP7A1的mRNA和蛋白表达水平而下调HMGCR的mRNA和蛋白表达水平,从而降低TC,LDL-c水平.这些结果表明黄连碱具有潜在的降胆固醇的药理活性,其分子机制可能是通过调节胆固醇代谢的关键基因LDLR,CYP7A1和HMGCR的mRNA和蛋白表达而达到降胆固醇的效果.该研究为开发新的具有降胆固醇活性的天然药物奠定了良好的理论基础.     

Quercetin improves nonalcoholic fatty liver by ameliorating inflammation,oxidative stress,and lipid metabolism in db/db mice

Multiphase pathological processes involve in Type 2 diabetes (T2DM)‐induced nonalcoholic fatty liver disease (NAFLD). However, the therapies are quite limited. In the present study, the hepatoprotective effects and underlying mechanisms of quercetin in T2DM‐induced NAFLD were investigated. T2DM‐induced NAFLD and quercetin treatment models were established in vivo and in vitro. The results revealed that quercetin alleviated serum transaminase levels and markedly reduced T2DM‐induced histological alterations of livers. Additionally, quercetin restored superoxide dismutase, catalase, and glutathione content in livers. Not only that, quercetin markedly attenuated T2DM‐induced production of interleukin 1 beta, interleukin 6, and TNF‐α. Accompanied by the restoration of the increased serum total bile acid (p = .0001) and the decreased liver total bile acid (p = .0005), quercetin could reduce lipid accumulation in the liver of db/db mice. Further mechanism studies showed that farnesoid X receptor 1/Takeda G‐protein‐coupled receptor 5 signaling pathways was involved in quercetin regulation of lipid metabolism in T2DM‐induced NAFLD. In high D‐glucose and free fatty acid cocultured HepG2 cells model, quercetin eliminated lipid droplets and restored the upregulated total cholesterol and triglyceride levels. Similar to the findings in mice, quercetin could also activate farnesoid X receptor 1/Takeda G‐protein‐coupled receptor 5 signaling pathway. These findings suggested that quercetin might be a potentially effective drug for the treatment of T2DM‐induced NAFLD.     

Quercetin protects against cisplatin‐induced acute kidney injury by inhibiting Mincle/Syk/NF‐κB signaling maintained macrophage inflammation

Acute kidney injury (AKI) with high incidence and mortality is the main cause of chronic kidney disease. Previous studies have indicated that quercetin, an abundant flavonoid in plants, exhibited renoprotective role in AKI. However, the underlying mechanism is largely unknown. In this study, we try to explore whether quercetin protects against AKI by inhibiting macrophage inflammation via regulation of Mincle/Syk/NF‐κB signaling. The results demonstrated that quercetin can significantly inhibit expression and secretion of IL‐1β, IL‐6, and TNF‐α in LPS‐induced bone marrow‐derived macrophages (BMDMs) and reduce activity of Mincle/Syk/NF‐κB signaling in vitro. We also found that quercetin can strongly reduce the concentration of serum creatinine, BUN, IL‐1β, IL‐6, and TNF‐α in cisplatin‐induced AKI model. Furthermore, quercetin down‐regulated protein levels of Mincle, phosphorylated Syk and NF‐κB in kidney macrophages of AKI, as well as inhibited M1, up‐regulated M2 macrophage activity. Notably, the down‐regulation of LPS‐induced inflammation by quercetin was reversed after adding TDB (an agonist of Mincle) in BMDMs, suggesting that quercetin suppresses macrophage inflammation may mainly through inhibiting Mincle and its downstream signaling. In summary, these findings clarified a new mechanism of quercetin improving AKI‐induced kidney inflammation and injury, which provides a new drug option for the clinical treatment of AKI.     

Scutellarin,a modulator of mTOR,attenuates hepatic insulin resistance by regulating hepatocyte lipid metabolism via SREBP‐1c suppression

High levels of consumption of saturated lipids have been largely associated with the increasing prevalence of metabolic diseases. In particular, saturated fatty acids such as palmitic acid (PA) have been implicated in the development of insulin resistance (IR). Scutellarin (Scu) is one of the effective traditional Chinese medicines considered beneficial for liver diseases and diabetes. In this study, we investigated the effect of Scu on IR and lipid metabolism disorders in vitro and in high fat diet (HFD)‐fed mice. In vitro, we found that Scu decreased insulin‐dependent lipid accumulation and the mRNA expression of CD36, Fasn, and ACC in PA‐treated HepG2 cells. Additionally, Scu upregulated Akt phosphorylation and improved the insulin signalling pathway. Moreover, Scu downregulated mammalian target of rapamycin (mTOR) phosphorylation and the n‐SREBP‐1c protein level and also reduced lipid accumulation via the mTOR‐dependent pathway, as confirmed by the molecular docking of Scu to mTOR. In HFD‐fed C57BL/6 mice, Scu improved oral glucose tolerance, pyruvate tolerance and the IR index and also increased the Akt phosphorylation level. Moreover, Scu reduced hepatocyte steatosis, decreased lipid accumulation and triglyceride levels, inhibited mTOR phosphorylation, and decreased the SREBP‐1c level in the liver. Taken together, these findings suggest that Scu ameliorates hepatic IR by regulating hepatocyte lipid metabolism via the mTOR‐dependent pathway through SREBP‐1c suppression.     

Improved Lipid Profile in Hyperlipidemic Patients Taking Vaccinium arctostaphylos Fruit Hydroalcoholic Extract: A Randomized Double‐Blind Placebo‐Controlled Clinical Trial

Dyslipidemia is a common contributory cause of cardiovascular disease. Vaccinium arctostaphylos L. (Caucasian whortleberry) fruit is rich of anthocyanins. Anthocyanins may exert cardioprotective effects by various mechanisms such as favorably modulating dyslipidemia. Therefore, in this randomized double‐blind placebo‐controlled clinical trial with hyperlipidemic (hypercholesterolemic and/or hypertriglyceridemic) patients aged 20–60 years, the effects of taking a standardized whortleberry fruit hydroalcoholic extract (one 350 mg capsule every 8 h for 2 months) on fasting blood levels of lipids, creatinine and liver enzymes including SGOT and SGPT were evaluated in 40 patients and compared with the placebo group (n = 40). The extract lowered the blood levels of total cholesterol (P < 0.001), triglyceride (P = 0.002) and low‐density lipoprotein cholesterol (LDL‐C) (P = 0.002), but increased the blood high‐density lipoprotein cholesterol (HDL‐C) levels (P < 0.001) without any significant effects on the blood levels of SGOT, SGPT and creatinine (P > 0.05) compared with the placebo group at the endpoint. Whortleberry reduced total cholesterol, triglyceride and LDL‐C 27.6%, 19.2% and 26.3%, respectively, but increased HDL‐C 37.5% compared with baseline. No adverse effects were reported. Short‐term treatment with whortleberry fruit appears safe and improves lipid profile in hyperlipidemic patients. Copyright © 2013 John Wiley & Sons, Ltd.