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The mammalian target of rapamycin (mTOR)-sterol regulatory element-binding proteins (SREBPs) signaling promotes lipogenesis. However, mTOR inhibitors also displayed a significant side effect of hyperlipidemia. Thus, it is essential to develop mTOR-specific inhibitors to inhibit lipogenesis. Here, we screened the endogenous inhibitors of mTOR, and identified that FKBP38 as a vital regulator of lipid metabolism. FKBP38 decreased the lipid content in vitro and in vivo via suppression of the mTOR/P70S6K/SREBPs pathway. 3,5,6,7,8,3ʹ,4ʹ-Heptamethoxyflavone (HMF), a citrus flavonoid, was found to target FKBP38 to suppress the mTOR/P70S6K/SREBPs pathway, reduce lipid level, and potently ameliorate hyperlipidemia and insulin resistance in high fat diet (HFD)-fed mice. Our findings suggest that pharmacological intervention by targeting FKBP38 to suppress mTOR/P70S6K/SREBPs pathway is a potential therapeutic strategy for hyperlipidemia, and HMF could be a leading compound for development of anti-hyperlipidemia drugs., Graphical abstract FKBP38 suppresses mTOR/P70S6K/SREBPs signaling and lipid level. HMF targets FKBP38 to ameliorate HFD-induced hyperlipidemia via suppressing mTOR/P70S6K/SREBPs pathway.Image 1

The accumulation of iron-dependent lipid peroxides is one of the important causes of NAFLD. The purpose of this study is to explore the effect of dehydroabietic acid (DA) on ferroptosis in nonalcoholic fatty liver disease (NAFLD) mice and its possible mechanisms. DA improved NAFLD and reduced triglycerides (TG), total cholesterol (TC), and lipid peroxidation level and inhibited ferroptosis in the liver of HFD-induced mice. DA binds with Keap1 to form 3 stable hydrogen bonds at VAL512 and LEU557 and increased nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response elemen (ARE) luciferase activity. DA promoted the expression downstream of Nrf2 such as heme oxygenase-1 (HO-1), glutathione (GSH) and its peroxidase 4 (GPX4), so as to eliminate the accumulation of reactive oxygen species (ROS) and reduce lipid peroxides malondialdehyde (MDA) in the liver. DA inhibited ferroptosis and increased the expression of key genes such as ferroptosis suppressor protein 1 (FSP1) in vitro and vivo. In all, DA may bind with Keap1, activate Nrf2-ARE, induce its target gene expression, inhibit ROS accumulation and lipid peroxidation, and reduce HFD-induced NAFLD.

Ethnopharmacological relevance Sea buckthorn is popularly used as a herbal medicine and food additive in the world. Sea buckthorn flavonoids (SF) is reported to have an ameliorative effect on obesity and hyperlipidemia (HLP). Aim To identify the major bioactive compounds and the lipid-lowering mechanism of SF. Methods We used network pharmacology analysis and in vitro experiments to identify the major bioactive compounds and the lipid-lowering mechanism of SF. Results A total of 12 bioactive compounds, 60 targets related to SF and HLP were identified, and a component-target-disease network was constructed. The KEGG analysis revealed that SF regulated cholesterol metabolism, fat digestion and absorption, and PPAR signaling pathways in HLP. The experimental validation indicated that sea buckthorn flavonoids extract (SFE) and 4 bioactive compounds reduced lipid droplet accumulation, up-regulated the mRNA expression of PPAR-γ, PPAR-α, ABCA1 and CPT1A, etc, down-regulated SREBP-2 and its target gene LDLR, which are closely related to cholesterol conversion into bile acids, de novo synthesis and fatty acids oxidation. The major bioactive flavonoid isorhamnetin (ISOR) also increased the protein expression of PPAR-γ, LXRα and CYP7A1. Conclusion SF might promote cholesterol transformation into bile acids and cholesterol efflux, inhibit cholesterol de novo synthesis and accelerate fatty acids oxidation for ameliorating HLP.

Dual-PPAR-α/γ agonist has the dual potentials to improve insulin resistance (IR) and hepatic steatosis associated with obesity. This study aimed to investigate whether dehydroabietic acid (DA), a naturally occurred compound, can bind to and activate both PPAR-γ and PPAR-α to ameliorate IR and hepatic steatosis in high-fat diet (HFD)-fed mice.. We found that DA formed stable hydrogen bonds with the ligand-binding domains of PPAR-γ and PPAR-α. DA treatment also promoted 3T3-L1 differentiation via PPAR-γ activation, and mitochondrial oxygen consumption in HL7702 cells via PPAR-α activation. In HFD-fed mice, DA treatment alleviated glucose intolerance and IR, and reduced hepatic steatosis, liver injury markers (ALT, AST), and lipid accumulation, and promoted mRNA expression of PPAR-γ and PPAR-α signaling elements involved in IR and lipid metabolism in vivo and in vitro, and inhibited mRNA expression of pro-inflammatory factors. Therefore, DA is a dual-PPAR-α/γ and PPAR-γ partial agonist, which can attenuate IR and hepatic steatosis induced by HFD-consumption in mice.

A new platform for triptolide (TP) delivery was prepared by conjugating TP to a carboxylmethyl chitosan (CMCS). Compared with the natural TP, the TP-conjugate (TP-CMCS) containing TP of ~5 wt% exhibited excellent aqueous solubility (&gt, 5 mg/mL). Results of in vitro experiments showed that TP-CMCS could relieve TP-induced inhibition on RAW264.7 cells and apoptosis, respectively. Compared with the TP group, TP-CMCS could effectively alleviate the toxicity injury of TP and decreased the mortality rate of the mice (p &lt, 0.05). TP-CMCS did not cause much damage to the liver (AST and ALT) and kidney (BUN and CRE) (p &lt, 0.05). After administration, the levels of IL-6, IL-1&beta, and TNF-&alpha, decreased, and the arthritis detumescence percentages increased significantly, and the bony erosion degree was distinctly decreased in the TP-CMCS groups and TP group. Our results suggested that TP-CMCS was a useful carrier for the treatment of RA, which enhanced aqueous solubility of free TP and reduced drug toxicity in vitro and in vivo.

Carnosic acid (CA), from rosemary, a food additive used for long history in western countries, reduces triglyceride, cholesterol and glucose levels. However, the detailed mechanisms contributing to these effects remain unclear. Here we investigate the potential mechanism of how CA regulates lipid metabolism. Using reporter cell lines, we found CA inhibited SREBPs activity, using radioactive isotope labeling, we found CA impeded de novo lipid synthesis, using gene silencing and inhibitors, we investigated the possible mechanism of how CA affects SREBPs stability. In hepatocytes, CA reduces the nuclear abundance of SREBPs and downregulates their target genes, thereby inhibiting the de novo biosynthesis of both fatty acids and cholesterol. Furthermore, in western type diet-induced obese mice, CA alleviates hyperlipidemia, fatty liver and insulin resistance by suppressing SREBPs target gene expression in the liver. Our results indicate that CA promotes the degradation of mature form of SREBPs via the 26S proteasome. To our knowledge, this study is the first to describe a small molecule that strongly reduces mature SREBPs.

SREBPs play important roles in the regulation of lipid metabolism, and are closely related to the occurrence and development of many metabolic diseases. Small molecular inhibitors of SERBPs are important tools in developing efficient treatment of metabolic diseases. However, there are no listing drug targeting SREBPs. Therefore, there is an urgent need to develop highly specific small molecules that inhibit SREBPs. In this study, using a hepatocyte-based high-throughput screening, we identified anhydroicaritin (AHI) as a novel inhibitor of SREBPs. HepG2, HL-7702, and human primary hepatocytes were used to verify the effects of AHI. We explored the mechanism by which AHI blocks the binding of SCAP/SREBPs complex with Sec23α/24D via regulating LKB1/AMPK/mTOR pathway. AHI reduced liver cell lipid level by preventing de novo lipogenesis. In diet induced obese mice, AHI ameliorated obesity, insulin resistance, fatty accumulation in liver and hyperlipemia. In conclusion, AHI improves diet-induced obesity and alleviates insulin resistance by suppressing SREBPs maturation which is dependent on LKB1/AMPK/mTOR pathway. Thus, AHI can serve as a leading compound for pharmacological control of metabolic diseases.

Celastrol is a promising drug candidate for treating diet-induced obesity, but the cytotoxicity and poor water solubility limit its clinical application. We prepared a novel celastrol conjugate (Cel-CMCS) with excellent water solubility (33.94 mg/mL), and then investigated its anti-obesity and toxic activities in diet-induced obese mice. Just as the parent celastrol, Cel-CMCS reduced body weight and body fat mass in an equally effective manner, but with lower toxicity. Collectively, Cel-CMCS provides a possible solution for the treatment of obesity in humans. In addition, the present study provided a practical experience of the development of carboxymethyl chitosan-based delivery system for poorly water-soluble drugs.

Menopausal metabolic syndrome (MMS) is a series of syndrome caused by ovarian function decline and hormone insufficiency, and is a high risk factor for cardiovascular diseases (CVD) and type II diabetes mellitus (T2DM). Erzhiwan (EZW), composed of Herba Ecliptae and Fructus Ligustri Lucidi, is a traditional Chinese herbal formula that has been used to treat menopausal syndrome for many years. We added Herba Epimedii, Radix Rehmanniae, and Fructus Corni into EZW, to prepare a new formula, termed Jiawei Erzhiwan (JE). The present study was designed to determine the anti-MMS effects of JE using ovariectomized (OVX) adult female rats that were treated with JE for 4 weeks, and β-tc-6 cells and INS cells were used to detected the protect effectiveness of JE. Our results showed JE could increase insulin sensitivity and ameliorated hyperlipidemia. Metabolomics analysis showed that the serum levels of branched and aromatic amino acids were down-regulated in serum by JE administration. Moreover, JE enhanced the function of islet β cells INS-1 and β-tc-6, through increasing the glucose stimulated insulin secretion (GSIS), which was abolished by estrogen receptor (ER) antagonist, indicating that JE functions were mediated by ER signaling. Additionally, JE did not induce tumorigenesis in rat mammary tissue or promoted proliferation of MCF-7 and Hela cells. In conclusion, our work demonstrated that JE ameliorated OVX-induced glucose and lipid metabolism disorder through activating estrogen receptor pathway and promoting GSIS in islet β cells, thus indicating that JE could be a safe and effective medication for MMS therapy.

Ethnopharmacological relevance Danshen and Sanqi Prescription (Dan-Qi) is commonly used to treat cardiovascular diseases (CVD) in China. Since Danshen and Sanqi are reported to ameliorate lipid metabolism disorders at treatment of cardiovascular diseases. Meanwhile, it is reported that co-administration of Danshen and Sanqi exhibited significant pharmacokinetic herb–herb interactions. We reasoned that Danshen and Sanqi combination could be potentially function synergistically in treating diet induced insulin resistance. Materials and methods Using high calori food induced Drosophila and mice models, we assessed Danshen and Sanqi treatment for their anti-diabetic effects. Results The combination of Danshen and Sanqi (Dan-Qi) effectively improved fat and glucose metabolism of the high-sugar and high-fat diet fed fruit flies. More importantly, Dan-Qi significantly ameliorated hyperlipidemia and hyperglycemia phenotype caused in high-fat diet induced obesity (DIO) mouse model. The Dan-Qi treated DIO mice showed lower fasting insulin, triglycerides, total and low-density lipoprotein cholesterol (LDL-C) levels in plasma, much better than Danshen or Sanqi treated alone. It was shown that Dan-Qi prescription reduced fat accumulation in the liver with Sanqi playing the major role. Interestingly, it was not Danshen or Sanqi alone, but the combination markedly increased glycogen deposition in mice liver. Quantitative RT-PCR showed Dan-Qi increased liver glycogen synthesis gene like Glut-1, GK, and Glut-4, reduced fat and cholesterol anabolism genes such as SREBP-1c, ACC, ATP-CL, ACS. Meanwhilpose tissues and muscle tissues, the glucose and fat metabolism genes are changed accordingly to pro-catabolism status. Notably, endogenous plasma metabolites of Dan-Qi treated mice displayed much better overral rectifying effects than the Danshen or Sanqi alone. Conclusions Our data demonstrated that Danshen and Sanqi combination exerted significant anti-diabetic efficacy, and Dan-Qi prescription could be potentially considered as a therapeutic application in diabetes.