Laurolitsine ameliorates type 2 diabetes by regulating the hepatic LKB1-AMPK pathway and gut microbiota.

BACKGROUND: Type 2 diabetes mellitus (DM) is a highly prevalent chronic metabolic disease. Effective antidiabetic drugs are needed to improve and expand the available treatments. Using the ob/ob diabetic mouse model, we previously demonstrated that the alkaloid-rich extract from Litsea glutinosa bark (CG) has potent antidiabetic effects and that laurolitsine (LL) is the richest alkaloid in CG. PURPOSE: We conducted a systematic investigation of the antidiabetic effects and potential mechanisms of LL in vitro and in vivo. METHODS: The antidiabetic effects of LL and its mechanisms of action were explored in HL-7702 hepatocytes in vitro and in db/db mice in vivo by a series of experiments, including cellular toxicity analysis, glucose consumption analysis, serum/liver biochemical analysis, pathological examinations, Western blots, RNA-seq analysis, and gut microbiota analysis. RESULTS: LL stimulated glucose consumption and activated AMP-activated protein kinase (AMPK) without inducing lactic acid production or cytotoxicity in vitro. LL had potent antidiabetic effects with hypoglycemic activity in vivo. It improved insulin resistance, glucose tolerance and lipid metabolism; protected liver, renal and pancreatic functions; and promoted weight loss in db/db mice. Transcriptomic analysis suggested that the antidiabetic effects of LL involved the regulation of mitochondrial oxidative phosphorylation. We further demonstrated that LL effectively activated the hepatic liver kinase B1 (LKB1)/AMPK pathway by regulating the ADP/ATP ratio. Simultaneously, LL significantly modulated the gut microbial community, specifically decreasing the abundances of Mucispirillum schaedleri and Anaerotruncus_sp_G3_2012, which might also contribute to its antidiabetic effects. CONCLUSION: These results suggest that LL is a promising antidiabetic drug candidate that may improve glucolipid metabolism via modulation of the hepatic LKB1/AMPK pathway and the gut microbiota.

Nootkatone, a Sesquiterpene Ketone From Alpiniae oxyphyllae Fructus, Ameliorates Metabolic-Associated Fatty Liver by Regulating AMPK and MAPK Signaling.

Metabolic-associated fatty liver disease (MAFLD) is becoming more common due to lifestyle changes. A long-term high-fat and high-glucose diet induces glycolipid metabolism disorders in the liver, which results in the development of MAFLD. To date, there is no specific clinically useful therapeutics for this disease. Natural products or synthetic compounds were screened and investigated to find effective agents for treating MAFLD. In this study, nootkatone (Nok), a natural sesquiterpene ketone isolated from Alpiniae oxyphyllae fructus, was explored for its potential to treat MAFLD, and underlying mechanisms were studied. Our results show that Nok dramatically ameliorated the disordered lipid and glucose metabolism in MAFLD mice, decreased fat accumulation in hepatic tissue, and improved liver injury. Inflammation, metabolic disorder, and oxidative stress were ameliorated in liver tissue based on RNA-seq transcriptome comparison between a Nok-treated group and an MAFLD model group. Furthermore, Nok significantly activated AMPK activity and inhibited MAPK activity, especially the p38 and JNK signaling pathways, in vivo based on western blot analysis. The pharmaceutical effects and potential signaling pathways impacted by Nok were also investigated in L02 cells. Nok significantly promoted the consumption of glucose and decreased the deposition of triglycerides in vitro. The p-AMPKα level was notably upregulated by Nok, indicating dramatic AMPK activation. In addition, Nok decreased the levels of p-ERK1/2, p-p38, and p-JNK. Nok also inhibited the activation of MAPK signaling and, thus, alleviated MAFLD development. Our results suggest that Nok may be useful in treating MAFLD. Nok may ameliorate MAFLD by regulating glycolipid metabolism disorders by activating AMPK and inhibiting MAPK activity. Collectively, this study suggests that Nok is an effective compound for the treatment of MAFLD.

Mangiferin Ameliorates HFD-Induced NAFLD through Regulation of the AMPK and NLRP3 Inflammasome Signal Pathways.

Nonalcoholic fatty liver disease (NAFLD) is closely related to glycolipid metabolism and liver inflammation. And there is no effective drug approved for its clinical therapy. In this study, we focused on mangiferin (Man) and explored its effects and mechanisms on NAFLD treatment based on the regulation of glycolipid metabolism and anti-inflammatory in vivo and in vitro. The results exhibited that Man can significantly attenuate liver injury, insulin resistance, and glucose tolerance in high-fat diet- (HFD-) induced NAFLD mice and significantly reduce fat accumulation and inflammation in hepatic tissue of NAFLD mice. The transcriptome level RNA-seq analysis showed that the significantly different expression genes between the Man treatment group and the HFD-induced NAFLD model group were mainly related to regulation of energy, metabolism, and inflammation in liver tissue. Furthermore, western blots, real-time PCR, and immunohistochemistry experiments confirmed that Man significantly activated the AMPK signal pathway and inhibited NLRP3 inflammasome activation and pyroptosis in NAFLD mice. In in vitro cell experiments, we further confirmed that Man can promote glucose consumption and reduce intracellular triglyceride (TG) accumulation induced by free fatty acids in HepG2 cells and further that it can be blocked by AMPK-specific inhibitors. Western blot results showed that Man upregulated p-AMPKα levels and exhibited a significant AMPK activation effect, which was blocked by compound C. At the same time, Man downregulated the expression of NLRP3 inflammasome-related proteins and inhibited the activation of NLRP3 inflammasome, alleviating cell pyroptosis and inflammation effects. These results indicate that Man anti-NAFLD activity is mediated through its regulation of glucolipid metabolism by AMPK activation and its anti-inflammatory effects by NLRP3 inflammasome inhibition. Our study indicates that Man is a promising prodrug for the therapy of NAFLD patients.

Cordycepin promotes browning of white adipose tissue through an AMP-activated protein kinase (AMPK)-dependent pathway

Obesity is a worldwide epidemic. Promoting browning of white adipose tissue (WAT) contributes to increased energy expenditure and hence counteracts obesity. Here we show that cordycepin (Cpn), a natural derivative of adenosine, increases energy expenditure, inhibits weight gain, improves metabolic profile and glucose tolerance, decreases WAT mass and adipocyte size, and enhances cold tolerance in normal and high-fat diet-fed mice. Cpn markedly increases the surface temperature around the inguinal WAT and turns the inguinal fat browner. Further investigations show that Cpn induces the development of brown-like adipocytes in inguinal and, to a less degree, epididymal WAT depots. Cpn also increases the expression of uncoupling protein 1 (UCP1) and other thermogenic genes in WAT and 3T3-L1 differentiated adipocytes, in which AMP-activated protein kinase (AMPK) plays an important role. Our results provide novel insights into the function of Cpn in regulating energy balance, and suggest a potential utility of Cpn in the treatment of obesity.

Syringaresinol-4---d-glucoside alters lipid and glucose metabolism in HepG2 cells and C2C12 myotubes

Syringaresinol-4---d-glucoside (SSG), a furofuran-type lignan, was found to modulate lipid and glucose metabolism through an activity screen of lipid accumulation and glucose consumption, and was therefore considered as a promising candidate for the prevention and treatment of metabolic disorder, especially in lipid and glucose metabolic homeostasis. In this study, the effects of SSG on lipogenesis and glucose consumption in HepG2 cells and C2C12 myotubes were further investigated. Treatment with SSG significantly inhibited lipid accumulation by oil red O staining and reduced the intracellular contents of total lipid, cholesterol and triglyceride in HepG2 cells. No effect was observed on cell viability in the MTT assay at concentrations of 0.1-10 μmol/L. SSG also increased glucose consumption by HepG2 cells and glucose uptake by C2C12 myotubes. Furthermore, real-time quantitative PCR revealed that the beneficial effects were associated with the down-regulation of sterol regulatory element-binding proteins-1c, -2 (), fatty acid synthase (), acetyl CoA carboxylase () and hydroxyl methylglutaryl CoA reductase (), and up-regulation of peroxisome proliferator-activated receptors alpha and gamma (and). SSG also significantly elevated transcription activity oftested by luciferase assay. These results suggest that SSG is an effective regulator of lipogenesis and glucose consumption and might be a candidate for further research in the prevention and treatment of lipid and glucose metabolic diseases.

Pandanus tectorius derived caffeoylquinic acids inhibit lipid accumulation in HepG2 hepatoma cells through regulation of gene expression involved in lipid metabolism / 药学学报

The fruit of Pandanus tectorius (PTF) has a long history of use as a folk medicine to treat hyperlipidemia in Hainan province, South China. Our previous studies have shown that the n-butanol extract of PTF is rich in caffeoylquinic acids and has an adequate therapeutic effect on dyslipidemic animals induced by high-fat diet. In this work, seven caffeoylquinic acids isolated from PTF were screened for the lipid-lowering activity in HepG2 hepatoma cells. Oil-Red O staining, microscopy and intracellular triglyceride (TG) and total cholesterol (TC) quantification showed that 3-O-caffeoylquinic acid (3-CQA), 3, 5-di-O-caffeoylquinic acid (3,5-CQA), and 3,4,5-tri-O-caffeoylquinic acid (3,4,5-CQA) significantly inhibited lipid accumulation induced by oleic acid and decreased intracellular levels of TC and TG in a dose-dependent manner. These three caffeoylquinic acids showed no significant cytotoxicity at concentrations of 1 -50 μmol x L(-1) as determined by MTT assay. Realtime quantitative PCR revealed that 3-CQA and 3, 5-CQA significantly increased the expression of lipid oxidation-related genes PPARα, CPT-1 and ACOX1 while 3-CQA, 3, 5-CQA and 3,4,5-CQA decreased the expression of lipogenic genes SREBP-1c, SREBP-2, HMGR, ACC, FAS. Overall, 3-CQA, 3, 5-CQA and 3, 4, 5-CQA may be the principal hypolipidemic components in PTF which can decrease intracellular lipid accumulation through up-regulating the expression of lipid oxidative genes and down-regulating the expression of lipogenic genes.