Natural alkaloid bouchardatine ameliorates metabolic disorders in high-fat diet-fed mice by stimulating the sirtuin 1/liver kinase B-1/AMPK axis

AMPK in Intestinal Health and Disease: A Multifaceted Therapeutic Target for Metabolic and Inflammatory Disorders

The intestines play essential roles in nutrient absorption and immune function and help maintain a protective barrier. Disruptions to its function can result in various diseases, including metabolic disorders, inflammation, and cancer. As a key regulator of cellular energy levels, 5'-adenosine monophosphate-activated protein kinase (AMPK) is essential for intestinal health. Beyond its established metabolic role, emerging evidence suggests that AMPK exerts profound effects on intestinal cell physiology, influencing cell proliferation and differentiation, inflammation, autophagy, barrier integrity, and smooth muscle contractility. Here, we explore the structure and regulation of AMPK, as well as its diverse roles in intestinal diseases and potential as a therapeutic target. Our findings reveal that AMPK is a multifaceted regulator of intestinal health, modulating various cellular processes and intestinal diseases. It plays a dual role in cancer, acting as both a tumor suppressor and promoter, and it regulates inflammatory pathways, autophagy, tight junction formation, and smooth muscle contractility. Both natural and synthetic AMPK activators offer promise as therapeutic agents. This review of AMPK's mechanisms and activators offers valuable insights for developing novel therapies for intestinal disorders. Further research is needed to fully define AMPK's roles and therapeutic potential.

Graphene-Based Far-Infrared Therapy Promotes Adipose Tissue Thermogenesis and UCP1 Activation to Combat Obesity in Mice

Hyperthermia (HT) has broad potential for disease treatment and health maintenance. Previous studies have shown that far-infrared rays (FIRs) at 8-10 μm can potentially reduce inflammation, oxidative stress, and gut microbiota imbalance. However, the effects of FIR HT on energy metabolism require further investigation. To investigate the effects of graphene-FIR HT therapy on diet-induced obesity and their regulatory mechanisms in energy metabolism disorders. After 8 weeks of hyperthermia, mice fed standard chow or a high-fat diet (HFD) underwent body composition analysis. Energy expenditure was measured using metabolic cages. The protein changes in adipose tissue were detected by molecular technology. Graphene-FIR therapy effectively mitigated body fat accumulation, improved dyslipidemia, and impaired liver function while enhancing insulin sensitivity. Furthermore, graphene-FIR therapy increased VO2, VCO2, and EE levels in HFD mice to exhibit enhanced metabolic activity. The therapy activated the AMPK/PGC-1α/SIRT1 pathway in adipose tissue, increasing the expression of uncoupling protein 1 (UCP1) and glucose transporter protein four (GLUT4), activating the thermogenic program in adipose tissue, and improving energy metabolism disorder in HFD mice. In short, graphene-FIR therapy represents a comprehensive approach to improving the metabolic health of HFD mice.

L-aspartate ameliorates diet-induced obesity by increasing adipocyte energy expenditure

AIMS

Obesity always leads to profound perturbation of metabolome. Metabolome studies enrich the knowledge on associations between endogenous metabolites and obesity, potentially providing innovative strategies for the development of novel anti-obesity pharmacotherapy. This study aims to identify an endogenous metabolite that regulates energy expenditure and to explore its application for obesity treatment.

MATERIALS AND METHODS

C57BL/6 mice were fed with a high-fat and high-cholesterol (HFC) diet, comprising 60% fat and 1.2% cholesterol, for 12 weeks to induce obesity. Significant metabolites were identified in the livers of both health and obese mice through comparative hepatic metabolomics analysis. Correlation between serum or adipose L-aspartate level and body weight in obese mice, as well as human body mass index (BMI), was evaluated. In addition, saline or 200 mg/kg L-aspartate was orally administrated to HFC diet mice and HFC diet-induced obese mice for 6-7 weeks. Body weight, adipose tissue weight, glucose tolerance and liver damage were assessed to evaluate the effect on obesity prevention and treatment. Comprehensive lab animal monitoring system (CLAMS) and seahorse assay were employed to investigate the regulatory effect of L-aspartate on energy metabolism in vivo and in vitro, respectively. 3T3-L1 preadipocytes and murine white adipose tissue (WAT) were utilized to examine the impact of L-aspartate on adipocyte adipogenesis and lipogenesis and cellular signalling pathway in vitro and in vivo.

RESULTS

L-aspartate, an approved drug for liver injury and chronic fatigue, was identified as an endogenous inducer of energy expenditure. Serum or adipose L-aspartate levels were found to be negatively correlated with the severity of obesity in both humans and mice. Administration of L-aspartate to HFC diet mice led to a significant reduction in body weight, with decreases of 14.5% in HFC diet mice and 8.5% in HFC diet-induced obese mice, respectively. In addition, the treatment improved related metabolic syndrome (Figure 2 and Figure S3). These therapeutics were associated with enhancements in whole-body energy expenditure and suppression of adipocyte adipogenesis along with activation of Adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathway.

CONCLUSION

L-aspartate may serve as a novel endogenous inducer of energy expenditure and suppressor of adipogenesis and lipogenesis along with activation of AMPK, thereby offering a promising therapeutic strategy for obesity prevention and treatment.

Unlocking Therapeutic Potential: Camphorquinone's Role in Alleviating Non-Alcoholic Fatty Liver Disease via SIRT1/LKB1/AMPK Pathway Activation

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a pathological condition that increase the risk of simple steatosis to hepatocellular carcinoma. This study aimed to investigate the biological effects of camphorquinone (CQ) in a high-fat diet (HFD)-fed and low dose streptozotocin (STZ)-induced mouse model, widely used to mimic the concurrent development of NAFLD pathological conditions in vivo, and a free fatty acid-induced hepatic steatosis cell model in vitro.

METHODS

CQ (10 or 30 mg/kg/day; i.p.) was injected for three weeks, and fasting blood glucose levels, glucose tolerance, and liver lipid metabolism were assessed.

RESULTS

CQ administration alleviated the increase in body and liver weights and improved glucose tolerance in NAFLD mice model. CQ also reduced the gene expression levels of lipid biosynthesis and inflammation markers, while increasing the levels of fatty acid oxidation markers in liver tissues and HepG2 cells. These beneficial effects of CQ were mediated via activation of the sirtuin 1 (SIRT1)/adenosine monophosphate-activated protein kinase (AMPK) signalling pathway in vitro and in vivo.

CONCLUSION

Collectively, our data suggest that CQ improves liver lipid metabolism and reduces blood glucose levels via activation of the SIRT1/serine/threonine kinase 11 (STK11/LKB1)/AMPK axis.

Therapeutic potential of the flavonoid compound Licochalcone D in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent chronic liver disease associated with type 2 diabetes, which doubles the risk of developing this condition. Various flavonoid compounds have a positive effect on lipid metabolism, inflammation, and insulin resistance and can contribute to slowing down the progression of MASLD. In the current study, we investigated the biological effects of Licochalcone D (Lico D), a flavonoid, in a metabolic disease model. Oil Red O staining, quantitative real-time polymerase chain reaction, and western blotting were performed. For in vivo experiments, we used high-fat diet (60 %) plus low-dose streptozotocin (30 mg/kg; 5 days; intraperitoneal)-induced metabolic disease mouse model and evaluated lipid metabolism. We observed that Lico D reduced lipid accumulation and increased lipid metabolism both in vitro and in vivo. Additionally, we identified that the AMP-activated protein kinase and Sirtuin 1 pathways were activated in the mouse liver and hepatic steatosis cell model. In silico analysis revealed that Lico D passes the "Lipinski Rule of Five," which indicates drug-likeness properties. In conclusion, our findings highlight the role of Lico D in improving metabolic dysfunction-associated steatotic liver disease.

Potential Anti-Obesity Effect of Hazel Leaf Extract in Mice and Network Pharmacology of Selected Polyphenols

Background: Obesity is gradually becoming a widespread health problem, and treatment using natural compounds has seen an increasing trend. As a by-product of hazelnut, hazel leaf is usually disposed of as waste, but it is widely used in traditional and folk medicines around the world. Aim of this study: Based on previous studies, the effects of the regulation of lipid metabolism and the mechanism of hazel leaf polyphenol extraction obesity were investigated. Methods: In this study, a high-fat diet-fed mouse model of obesity and 3T3-L1 preadipocytes were established. The ameliorative effects of the hazel leaf polyphenol extract on obesity and the regulating lipid metabolisms were explored based on network pharmacology, gut microbiota, and molecular docking. Results: Network pharmacology showed that hazel leaf polyphenols may play a role by targeting key targets, including PPARγ, and regulating the PPAR signaling pathway. They significantly improved body weight gain, the liver index, and adiposity and lipid levels; regulated the gut microbiota and short-chain fatty acid contents; down-regulated the expression of lipid synthesis proteins SREBP1c, PPARγ, and C/EBP-α; and up-regulated the expression of p-AMPK in obese mice. They inhibited the differentiation of 3T3-L1 cells, and the expression of related proteins is consistent with the results in vivo. The molecular docking results indicated that gallic acid, quercetin-3-O-beta-D-glucopyranoside, quercetin, myricetin, and luteolin-7-O-glucoside in the hazel leaf polyphenol extract had strong binding activities with PPARγ, C/EBP-α, and AMPK. Conclusions: The results demonstrate that the hazel leaf polyphenol extract can improve obesity by regulating lipid metabolism, which provides a valuable basis for developing health products made from hazel leaf polyphenols in the future.

Development of Novel N-Acylhydrazone Derivatives with High Anti-obesity Activity and Improved Safety by Exploring the Pharmaceutical Properties of Aldehyde Group

The discovery of effective and safe antiobesity agents remains a challenging yet promising field. Our previous studies identified Bouchardatine derivatives as potential antiobesity agents. However, the 8a-aldehyde moiety rendered them unsuitable for drug development. In this study, we designed two series of novel derivatives to modify this structural feature. Through a structure-activity relationship study, we elucidated the role of the 8a-aldehyde group in toxicity induction. We identified compound 14d, featuring an 8a-N-acylhydrazone moiety, which exhibited significant lipid-lowering activity and reduced toxicity. Compound 14d shares a similar lipid-lowering mechanism with our lead compound 3, but demonstrates improved pharmacokinetic properties and safety profile. Both oral and injectable administration of 14d significantly reduced body weight gain and ameliorated metabolic syndrome in diet-induced obese mice. Our findings identify 14d as a promising antiobesity agent and highlight the potential of substituting the aldehyde group with an N-acylhydrazone to enhance drug-like properties.

Natural compounds as obesity pharmacotherapies

Obesity has become a serious global public health problem, affecting over 988 million people worldwide. Nevertheless, current pharmacotherapies have proven inadequate. Natural compounds have garnered significant attention due to their potential antiobesity effects. Over the past three decades, ca. 50 natural compounds have been evaluated for the preventive and/or therapeutic effects on obesity in animals and humans. However, variations in the antiobesity efficacies among these natural compounds have been substantial, owing to differences in experimental designs, including variations in animal models, dosages, treatment durations, and administration methods. The feasibility of employing these natural compounds as pharmacotherapies for obesity remained uncertain. In this review, we systematically summarized the antiobesity efficacy and mechanisms of action of each natural compound in animal models. This comprehensive review furnishes valuable insights for the development of antiobesity medications based on natural compounds.

Marine fungus Aspergillus c1. sp metabolite activates the HSF1/PGC-1α axis, inducing a thermogenic program for treating obesity

Background and aims: Obesity is one of the most prevalent diseases worldwide with less ideal approved agents in clinic. Activating the HSF1/PGC-1α axis in adipose tissues has been reported to induce thermogenesis in mice, which presents a promising therapeutic avenue for obesity treatment. The present study aimed to identified novel natural HSF1 activator and evaluated the therapeutic effects of the newly discovered compound on obesity-associated metabolic disorders and the molecular mechanisms of these effects. Methods: Our previous reported HSF1/PGC-1α activator screening system was used to identify novel natural HSF1 activator. The PGC-1α luciferase activity, immunoblot, protein nuclear-translocation, immunofluorescence, chromatin immunoprecipitation assays were used to evaluate the activity of compound HN-001 in activating HSF1. The experiments of mitochondrial number measurement, TG assay and imaging, cellular metabolic assay, gene assays, and CRISPR/Cas 9 were applied for investigating the metabolic effect of HN-001 in C3H10-T1/2 adipocytes. The in vivo anti-obesity efficacies and beneficial metabolic effects of HN-001 were evaluated by performing body and fat mass quantification, plasma chemical analysis, GTT, ITT, cold tolerance test, thermogenesis analysis. Results: HN-001 dose- and time-dependently activated HSF1 and induced HSF1 nuclear translocation, resulting in an enhancement in binding with the gene Pgc-1α. This improvement induced activation of adipose thermogenesis and enhancement of mitochondrial oxidation capacity, thus inhibiting adipocyte maturation. Deletion of HSF1 in adipocytes impaired mitochondrial oxidation and abolished the above beneficial metabolic effects of HN-001, including adipocyte browning induction, improvements in mitogenesis and oxidation capacity, and lipid-lowering ability. In mice, HN-001 treatment efficiently alleviated diet-induced obesity and metabolic disorders. These changes were associated with increased body temperature in mice and activation of the HSF1/PGC-1α axis in adipose tissues. UCP1 expression and mitochondrial biogenesis were increased in both white and brown adipose tissues of HN-001-treated mice. Conclusion: These data indicate that HN-001 may have therapeutic potential for obesity-related metabolic diseases by increasing the capacity of energy expenditure in adipose tissues through a mechanism involving the HSF1/PGC-1α axis, which shed new light on the development of novel anti-obesity agents derived from marine sources.

Identification of a natural PLA2 inhibitor from the marine fungus Aspergillus sp. c1 for MAFLD treatment that suppressed lipotoxicity by inhibiting the IRE-1α/XBP-1s axis and JNK signaling

Lipotoxicity is a pivotal factor that initiates and exacerbates liver injury and is involved in the development of metabolic-associated fatty liver disease (MAFLD). However, there are few reported lipotoxicity inhibitors. Here, we identified a natural anti-lipotoxicity candidate, HN-001, from the marine fungus Aspergillus sp. C1. HN-001 dose- and time- dependently reversed palmitic acid (PA)-induced hepatocyte death. This protection was associated with IRE-1α-mediated XBP-1 splicing inhibition, which resulted in suppression of XBP-1s nuclear translocation and transcriptional regulation. Knockdown of XBP-1s attenuated lipotoxicity, but no additional ameliorative effect of HN-001 on lipotoxicity was observed in XBP-1s knockdown hepatocytes. Notably, the ER stress and lipotoxicity amelioration was associated with PLA2. Both HN-001 and the PLA2 inhibitor MAFP inhibited PLA2 activity, reduced lysophosphatidylcholine (LPC) level, subsequently ameliorated lipotoxicity. In contrast, overexpression of PLA2 caused exacerbation of lipotoxicity and weakened the anti-lipotoxic effects of HN-001. Additionally, HN-001 treatment suppressed the downstream pro-apoptotic JNK pathway. In vivo, chronic administration of HN-001 (i.p.) in mice alleviated all manifestations of MAFLD, including hepatic steatosis, liver injury, inflammation, and fibrogenesis. These effects were correlated with PLA2/IRE-1α/XBP-1s axis and JNK signaling suppression. These data indicate that HN-001 has therapeutic potential for MAFLD because it suppresses lipotoxicity, and provide a natural structural basis for developing anti-MAFLD candidates.

Design, synthesis and evaluation of 2-pyrimidinylindole derivatives as anti-obesity agents by regulating lipid metabolism

Obesity, a global pandemic posing a growing threat to human health, necessitates the development of effective and safe anti-obesity agents. Our previous studies highlighted the lipid-lowering effects of indolylquinazoline Bouchardatine and its derivatives. In this study, we employed scaffold hopping and simplification strategies to design and synthesize two new series derivatives by modifying the D ring. Extensive discussions have been conducted regarding the structure-activity relationship between lipid-lowering activity and the new compounds. These discussions have resulted in the discovery of 2-pyrimidinylindole derivatives as a promising scaffold for anti-obesity treatment. The new 2-pyrimidinylindole derivatives exhibited comparable lipid-lowering activity to the previously reported indolylquinazoline derivatives, including SYSU-3d and R17, with reduced toxicity. The most potent compound, 5a, demonstrated a larger therapeutic index, improved aqueous solubility and oral bioavailability compared to the previous lead compounds. In vivo evaluation indicated that 5a effectively reduced lipid accumulation in adipose tissue, improved glucose tolerance, and mitigated insulin resistance and liver function damage caused by a high-fat and high-cholesterol diet. Mechanism studies indicated that 5a may regulate lipid metabolism through the modulation of the PPARγ signaling pathway. Overall, our study has identified a highly active compound 5a, and provided the basis for further development of 2-pyrimidinylindole as a promising scaffold for obesity treatment.

The Synthesis and Biological Evaluation of 2-(1H-Indol-3-yl)quinazolin-4(3H)-One Derivatives

The treatment of many bacterial diseases remains a significant problem due to the increasing antibiotic resistance of their infectious agents. Among others, this is related to Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) and Mycobacterium tuberculosis. In the present article, we report on antibacterial compounds with activity against both S. aureus and MRSA. A straightforward approach to 2-(1H-indol-3-yl)quinazolin-4(3H)-one and their analogues was developed. Their structural and functional relationships were also considered. The antimicrobial activity of the synthesized compounds against Mycobacterium tuberculosis H₃₇Rv, S. aureus ATCC 25923, MRSA ATCC 43300, Candida albicans ATCC 10231, and their role in the inhibition of the biofilm formation of S. aureus were reported. 2-(5-Iodo-1H-indol-3-yl)quinazolin-4(3H)-one (3k) showed a low minimum inhibitory concentration (MIC) of 0.98 μg/mL against MRSA. The synthesized compounds were assessed via molecular docking for their ability to bind long RSH (RelA/SpoT homolog) proteins using mycobacterial and streptococcal (p)ppGpp synthetase structures as models. The cytotoxic activity of some synthesized compounds was studied. Compounds 3c, f, g, k, r, and 3z displayed significant antiproliferative activities against all the cancer cell lines tested. Indolylquinazolinones 3b, 3e, and 3g showed a preferential suppression of the growth of rapidly dividing A549 cells compared to slower growing fibroblasts of non-tumor etiology.

Natural products in pursuing novel therapies of nonalcoholic fatty liver disease and steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) are hepatic manifestations of systemic metabolic dysfunction, which affect one-quarter of the adult population worldwide as estimated, and exhibit high risk in progressing to hepatic fibrosis, cirrhosis, and hepatocellular carcinoma. Current drug discovery focuses on modifying homeostasis of lipids, carbohydrates, and cholesterol, as well as inhibiting inflammation and fibrogenesis. Many natural products show promising activities on various molecular targets involving these mechanisms; however, they have not been fully exploited. Since some compounds are components of healthy food, they may be employed in chemoprevention as adjuvants to lifestyle modification, while natural products such as alkaloids and sesquiterpenoids could serve as promising starting points for structural modifications and deserve further development.

The multifaceted roles of natural products in mitochondrial dysfunction

Mitochondria are the primary source of energy production in cells, supporting the metabolic demand of tissue. The dysfunctional mitochondria are implicated in various diseases ranging from neurodegeneration to cancer. Therefore, regulating dysfunctional mitochondria offers a new therapeutic opportunity for diseases with mitochondrial dysfunction. Natural products are pleiotropic and readily obtainable sources of therapeutic agents, which have broad prospects in new drug discovery. Recently, many mitochondria-targeting natural products have been extensively studied and have shown promising pharmacological activity in regulating mitochondrial dysfunction. Hence, we summarize recent advances in natural products in targeting mitochondria and regulating mitochondrial dysfunction in this review. We discuss natural products in terms of their mechanisms on mitochondrial dysfunction, including modulating mitochondrial quality control system and regulating mitochondrial functions. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products, emphasizing the potential value of natural products in mitochondrial dysfunction.

Isoliquiritigenin mitigates oxidative damage after subarachnoid hemorrhage in vivo and in vitro by regulating Nrf2-dependent Signaling Pathway via Targeting of SIRT1

BACKGROUND

Oxidative stress is a crucial factor leading to subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). Isoliquiritigenin has been verified as a powerful anti-oxidant in a variety of diseases models and can activate sirtuin 1 and nuclear factor-erythroid 2-related factor 2 (Nrf2) pathways. However, the effects of isoliquiritigenin against EBI after SAH and the underlying mechanisms remain elusive.

PURPOSE

The primary goal of this study is to verify the therapeutic effects of isoliquiritigenin on EBI after SAH and the possible molecular mechanisms.

STUDY DESIGN

A prechiasmatic cistern SAH model in rats and a hemoglobin incubation SAH model in primary neurons were established. Isoliquiritigenin was administered after SAH induction. EX527 was employed to inhibit sirtuin 1 activation and ML385 was used to suppress Nrf2 signaling.

METHODS

In our study, neurological scores, brain edema, biochemical estimation, western blotting, and histopathological study were performed to explore the therapeutic action of isoliquiritigenin against SAH.

RESULTS

Our data revealed that isoliquiritigenin significantly mitigated oxidative damage after SAH as evidenced by decreased reactive oxygen species overproduction and enhanced intrinsic anti-oxidative system. Concomitant with the reduced oxidative insults, isoliquiritigenin improved neurological function and reduced neuronal death in the early period after SAH. Additionally, isoliquiritigenin administration significantly enhanced Nrf2 and sirtuin 1 expressions. Inhibition of Nrf2 by ML385 reversed the anti-oxidative and neuroprotective effects of isoliquiritigenin against SAH. Moreover, inhibiting sirtuin 1 by EX527 pretreatment suppressed isoliquiritigenin-induced Nrf2-dependent pathway and abated the cerebroprotective effects of isoliquiritigenin. In primary cortical neurons, isoliquiritigenin treatment also ameliorated oxidative insults and repressed neuronal degeneration. The beneficial aspects of isoliquiritigenin were attributed to the promotion of sirtuin 1 and Nrf2 signaling pathways and were counteracted by EX527.

CONCLUSION

Our findings suggest that isoliquiritigenin exerts cerebroprotective effects against SAH-induced oxidative insults by modulating the Nrf2-mediated anti-oxidant signaling in part through sirtuin 1 activation. Isoliquiritigenin might be a new potential drug candidate for SAH.

Eupalinolide B attenuates lipopolysaccharide-induced acute lung injury through inhibition of NF-κB and MAPKs signaling by targeting TAK1 protein

Acute lung injury (ALI) is a life-threatening disease characterized by severe inflammatory response, which has no pharmacological therapy in clinic. In this study, we found that eupalinolide B (EB), a sesquiterpene lactone isolated from Eupatorium lindleyanum, significantly ameliorated lipopolysaccharide (LPS)-induced ALI in mice, which manifests as reduction in lung injury score, activity of myeloperoxidase, and release of cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1). In RAW264.7 murine macrophages, EB effectively inhibited LPS-induced production of nitric oxide (NO) and prostaglandin E2 (PGE₂) by down-regulating the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2), respectively. Mechanistically, EB not only blocked LPS-induced phosphorylation of inhibitor of nuclear factor kappa B kinase-α/β (IKKα/β), phosphorylation and degradation of inhibitor of nuclear factor-kappa B alpha (IκBα), and phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-κB) P65, but also suppressed LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs) in vitro or in vivo. Through cellular thermal shift assay and western blotting, EB was demonstrated to target and inactivate transforming growth factor β activated kinase-1 (TAK1), which is an important upstream kinase for the activation of NF-κB and MAPKs pathways. Additionally, EB-mediated actions were markedly abolished by dithiothreitol in LPS-exposed RAW264.7 cells, suggesting a crucial role of the α,γ-unsaturated lactone for the anti-inflammatory activity of EB. In conclusion, our findings showed that EB could effectively alleviate ALI in mice, and attenuate inflammatory response by inhibiting the activation of TAK1, and TAK1-mediated activation of NF-κB and MAPKs cascades.

Exogenous Nucleotides Improved the Oxidative Stress and Sirt-1 Protein Level of Brown Adipose Tissue on Senescence-Accelerated Mouse Prone-8 (SAMP8) Mice

Brown adipose tissue (BAT) is of great importance in rodents for maintaining their core temperature via non-shivering thermogenesis in the mitochondria. BAT′s thermogenic function has been shown to decline with age. The activation of adenosine 5′-monophosphate (AMP)-activated protein kinase/sirtuin-1 (AMPK/Sirt-1) is effective in regulating mitochondrial function. Exogenous nucleotides (NTs) are regulatory factors in many biological processes. Nicotinamide mononucleotide (NMN), which is a derivative of NTs, is widely known as a Sirt-1 activator in liver and muscle, but the effect of NMN and NTs on aging BAT has not been studied before. The purpose of this study was to investigate the effect of NTs on aging senescence-accelerated mouse prone-8 (SAMP8) mice. Senescence-accelerated mouse resistant 1 (SAMR1) mice were set as the model control group and NMN was used as the positive control. Male, 3 month old SAMP8 mice were divided into the SAMP8-normal chow (SAMP8-NC), SAMP8-young-normal chow (SAMP8-young-NC), NMN, NTs-free, NTs-low, NTs-medium, and NTs-high groups for long-term feeding. After 9 months of intervention, interscapular BAT was collected for experiments. Compared to the SAMP8-NC, the body weight and BAT mass were significantly improved in the NT-treated aging SAMP8 mice. NT supplementation had effects on oxidative stress in BAT. The concentration of malondialdehyde (MDA) was reduced and that of superoxide dismutase (SOD) increased significantly. Meanwhile, the expression of the brown adipocyte markers uncoupling protein-1 (UCP-1), peroxisome proliferator-activated receptor-γ coactlvator-1α (PGC-1α), and PR domain zinc finger protein 16 (PRDM16) were upregulated. The upregulated proteins may be activated via the Sirt-1 pathway. Thus, NT supplementation may be helpful to improve the thermogenesis of BAT by reducing oxidative stress and activating the Sirt-1 pathway.

Update of Indoles: Promising molecules for ameliorating metabolic diseases

Obesity and metabolic disorders have gradually become public health-threatening problems. The metabolic disorder is a cluster of complex metabolic abnormalities which are featured by dysfunction in glucose and lipid metabolism, and results from the increasing prevalence of visceral obesity. With the core driving factor of insulin resistance, metabolic disorder mainly includes type 2 diabetes mellitus (T2DM), micro and macro-vascular diseases, non-alcoholic fatty liver disease (NAFLD), dyslipidemia, and the dysfunction of gut microbiota. Strategies and therapeutic attention are demanded to decrease the high risk of metabolic diseases, from lifestyle changes to drug treatment, especially herbal medicines. Indole is a parent substance of numerous bioactive compounds, and itself can be produced by tryptophan catabolism to stimulate glucagon-like peptide-1 (GLP-1) secretion and inhibit the development of obesity. In addition, in heterocycles drug discovery, the indole scaffold is primarily found in natural compounds with versatile biological activity and plays a prominent role in drug molecules synthesis. In recent decades, plenty of natural or synthesized indole deriviatives have been investigated and elucidated to exert effects on regulating glucose hemeostasis and lipd metabolism. The aim of this review is to trace and emphasize the compounds containing indole scaffold that possess immense potency on preventing metabolic disorders, particularly T2DM, obesity and NAFLD, along with the underlying molecular mechanisms, therefore facilitate a better comprehension of their druggability and application in metabolic diseases.

Determination of IQZ23 in rat plasma using LC-MS/MS: consideration for matrix effect and internal standard interference

Aim: IQZ23, a novel β-indoloquinazoline derivative, is a potential therapeutic agent for obesity and related metabolic disorders. To assist pharmacokinetics evaluation, a quantitative method for IQZ23 in rat plasma is required. Methods & Results: An LC-MS/MS assay for the determination of IQZ23 in rat plasma was developed and validated for the first time. Chromatographic conditions were optimized to ameliorate matrix effect with direct monitoring of typical phospholipids, including phosphatidylcholine and lysophosphatidylcholine. The structural analog internal standard (SYSU-3d) was set at a proper concentration to avoid analyte sensitivity loss caused by internal standard interference. The well-validated method was employed in the pharmacokinetics study of IQZ23 in Sprague-Dawley rats. Conclusion: This study provided valuable references for the further preclinical study of IQZ23.

Recent advances in natural anti-obesity compounds and derivatives based on in vivo evidence: A mini-review

Obesity is not only viewed as a chronic aggressive disorder but is also associated with an increased risk for various diseases. Nonetheless, new anti-obesity drugs are an urgent need since few pharmacological choices are available on the market. Natural compounds have served as templates for drug discovery, whereas modified molecules from the leads identified based on in vitro models often reveal noncorresponding bioactivity between in vitro and in vivo studies. Therefore, to provide inspiration for the exploration of innovative anti-obesity agents, recent discoveries of natural anti-obesity compounds with in vivo evidence have been summarized according to their chemical structures, and the comparable efficacy of these compounds is categorized using animal models. In addition, several synthetic derivatives optimized from the phytochemicals are also provided to discuss medicinal chemistry achievements guided by natural sources.

Matrine counteracts obesity in mice via inducing adipose thermogenesis by activating HSF1/PGC-1α axis

Promoting energy expenditure is known to curb obesity and can be exploited for its treatment. Our previous study has demonstrated that activation of HSF1/PGC-1α axis efficiently induced mitochondrial biogenesis and adaptive oxidation and thus ameliorating lipid accumulation, however, whether it can be a therapeutic approach for metabolic disorders treatment needs explored. Here, a high-efficient and specific HSF1/PGC-1α activator screening system was established and the natural clinical liver-protecting agent matrine was identified as a robust HSF1/PGC-1α activator. Matrine treatment efficiently induced mitogenesis and thermogenic program in primary mouse adipose stem cell derived adipocytes by enriching HSF1 to the promoter of Pgc-1α. Deficiency of PGC-1α in adipocytes diminished the browning induction ability of matrine. Oral administration of matrine to the obese mice induced by high fat and high cholesterol diet increased energy expenditure and corrected the degeneration of thermogenesis in brown adipose tissue (BAT). Also, matrine treatment markedly induced the transformation of brown-like adipocytes in subcutaneous white adipose tissue (sWAT) via a mechanism of HSF1/PGC-1α, thereby attenuating obesity and myriads of metabolic disorders. This led to an improvement in adaptive thermogenesis to cold stimuli. These findings are of great significance in understanding the regulation mechanisms of the HSF1/PGC-1α axis in thermogenesis and providing a novel therapeutic approach for obesity treatment. Matrine may have potential therapeutic implications for the treatment of obesity in clinics.

The Effects of Antioxidants from Natural Products on Obesity, Dyslipidemia, Diabetes and Their Molecular Signaling Mechanism

Obesity is a risk factor that leads to the development of other diseases such as dyslipidemia and diabetes. These three metabolic disorders can occur simultaneously, hence, the treatment requires many drugs. Antioxidant compounds have been reported to have activities against obesity, dyslipidemia and diabetes via several mechanisms. This review aims to discuss the antioxidant compounds that have activity against obesity, dyslipidemia and diabetes together with their molecular signaling mechanism. The literature discussed in this review was obtained from the PUBMED database. Based on the collection of literature obtained, antioxidant compounds having activity against the three disorders (obesity, dyslipidemia and diabetes) were identified. The activity is supported by various molecular signaling pathways that are influenced by these antioxidant compounds, further study of which would be useful in predicting drug targets for a more optimal effect. This review provides insights on utilizing one of these antioxidant compounds as opposed to several drugs. It is hoped that in the future, the number of drugs in treating obesity, dyslipidemia and diabetes altogether can be minimized consequently reducing the risk of side effects.

Palladium oxidative addition complex-enabled synthesis of amino-substituted indolyl-4(3H)-quinazolinones and their antitumor activity evaluation

The indolyl-4(3H)-quinazolinone core is an important structural motif in functional molecules. However, few methods exist for its direct modification, which limits its potential application. Reported herein is a palladium-mediated amination of halogen-containing indolyl-4(3H)-quinazolinones with a variety of primary and secondary amines via the corresponding palladium oxidative addition complexes. The protocol allows the facile synthesis of indolyl-4(3H)-quinazolinone derivatives with amino groups at all the positions of the benzene ring in moderate to good yields with mild reaction conditions and good functional group tolerance. Furthermore, the antitumor activity of these products was evaluated.

A novel HSF1 activator ameliorates nonalcoholic steatohepatitis by stimulating mitochondrial adaptive oxidation

BACKGROUND AND PURPOSE

Nonalcoholic steatohepatitis (NASH) is the more severe form of metabolic associated fatty liver disease (MAFLD), and no pharmacologic treatment approved as yet. Identification of novel therapeutic targets and their agents are critical to overcome the current inadequacy of drug treatment for NASH.

EXPERIMENTAL APPROACH

The correlation between heat shock factor 1 (HSF1) levels and the development of NASH and the target genes of HSF1 in hepatocyte were revealed by chromatin-immunoprecipitation sequencing. The effects and mechanisms of SYSU-3d in alleviating NASH were examined in relevant cell models and mouse models (the Ob/Ob mice, high-fat and high-cholesterol diet, the methionine-choline deficient diet fed mice). The drug-like properties of SYSU-3d in vivo were evaluated.

KEY RESULTS

HSF1 is progressively reduced with mitochondrial dysfunction in NASH pathogenesis and activation of this transcription factor by its newly-identified activator SYSU-3d efficiently ameliorated all manifestations of NASH in mice. When activated, the phosphorylated HSF1 (Ser326) translocated to nucleus and bound to the promoter of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) to induce mitochondrial biogenesis, thus increasing mitochondrial adaptive oxidation and inhibiting oxidative stress. The deletion of HSF1 and PGC-1α or recovery of HSF1 in HSF1-deficiency cells revealed the HSF1/PGC-1α metabolic axis mainly responsible for the anti-NASH effects of SYSU-3d independent of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK).

CONCLUSION AND IMPLICATIONS

Activation of HSF1 is a practicable therapeutic approach for NASH treatment via the HSF1/PGC-1α/mitochondrial axis, and SYSU-3d would take into consideration as a potential candidate for the treatment of NASH.

Recent developments in natural products for white adipose tissue browning

Excess accumulation of white adipose tissue (WAT) causes obesity which is an imbalance between energy intake and energy expenditure. Obesity is a serious concern because it has been the leading causes of death worldwide, including diabetes, stroke, heart disease and cancer. Therefore, uncovering the mechanism of obesity and discovering anti-obesity drugs are crucial to prevent obesity and its complications. Browning, inducing white adipose tissue to brown or beige (brite) fat which is brown-like fat emerging in WAT, becomes an appealing therapeutic strategy for obesity and metabolic disorders. Due to lack of efficacy or intolerable side-effects, the clinical trials that promote brown adipose tissue (BAT) thermogenesis and browning of WAT have not been successful in humans. Obviously, more specific means still need to be developed to activate browning of white adipose tissue. In this review, we summarized seven kinds of natural products (alkaloids, flavonoids, terpenoids, long chain fatty acids, phenolic acids, else and extract) promoting white adipose tissue browning which can ameliorate the metabolic disorders, including obesity, dislipidemia, insulin resistance and diabetes. Since natural products are important drug sources and the browning property plays a significant role in not only obesity treatment but also in type 2 diabetes (T2DM) improvement, natural products of inducing browning may be an irreplaceable drug discovery orientation for obesity, diabetes and even other metabolic disorders.

Nectandrin B-mediated activation of the AMPK pathway prevents cellular senescence in human diploid fibroblasts by reducing intracellular ROS levels

Nectandrin B (NecB) is a bioactive lignan compound isolated from Myristica fragrans (nutmeg), which functions as an activator of AMP-activated protein kinase (AMPK). Because we recently found that treatment with NecB increased the cell viability of old human diploid fibroblasts (HDFs), the underlying molecular mechanism was investigated. NecB treatment in old HDFs reduced the activity staining of senescence-associated β-galactosidase and the levels of senescence markers, such as the Ser¹⁵ phosphorylated p53, caveolin-1, p21^waf1, p16^ink4a, p27^kip1, and cyclin D1. NecB treatment increased that in S phase, indicating a enhancement of cell cycle entry. Interestingly, NecB treatment ameliorated age-dependent activation of AMPK in old HDFs. Moreover, NecB reversed the age-dependent expression and/or activity changes of certain sirtuins (SIRT1-5), and cell survival/death-related proteins. The transcriptional activity of Yin-Yang 1 and the expression of downstream proteins were elevated in NecB-treated old HDFs. In addition, NecB treatment exerted a radical scavenging effect in vitro, reduced cellular ROS levels, and increased antioxidant enzymes in old HDFs. Moreover, NecB-mediated activation of the AMPK pathway reduced intracellular ROS levels. These results suggest that NecB-induced protection against cellular senescence is mediated by ROS-scavenging through activation of AMPK. NecB might be useful in ameliorating age-related diseases and extending human lifespan.

Low Expression of Sirtuin 1 in the Dairy Cows with Mild Fatty Liver Alters Hepatic Lipid Metabolism

Simple Summary

Sirtuin 1 (SIRT1), a NAD-dependent histone deacetylase, is involved in oxidative stress and lipid metabolism regulation. Limited studies exist regarding the role of SIRT1 in lipid metabolism disorder in periparturient dairy cows. This study explores the effect of hepatic steatosis on the expression of the SIRT1 gene and protein and the proteins encoded by the genes downstream to it, all of which are involved in lipid metabolism in the liver. Control cows (n = 6, parity 3.0 ± 2.0, milk production 28 ± 47 kg/d) and mild fatty liver cows (n = 6, parity 2.3 ± 1.5, milk production 20 ± 6 kg/d) were retrospectively selected based on liver triglycerides (TG) content (% wet liver). The present study indicates that low SIRT1 expression caused by hepatic steatosis promotes hepatic fatty acid synthesis and inhibits fatty acid β-oxidation. We believe that our study makes a significant contribution to the literature because it demonstrates that hepatic steatosis is associated with increased hepatic fatty acid synthesis, inhibited fatty acid β-oxidation and reduced lipid transport.

Abstract

Dairy cows usually experience negative energy balance coupled with an increased incidence of fatty liver during the periparturient period. The purpose of this study was to investigate the effect of hepatic steatosis on the expression of the sirtuin 1 (SIRT1), along with the target mRNA and protein expressions and activities related to lipid metabolism in liver tissue. Control cows (n = 6, parity 3.0 ± 2.0, milk production 28 ± 7 kg/d) and mild fatty liver cows (n = 6, parity 2.3 ± 1.5, milk production 20 ± 6 kg/d) were retrospectively selected based on liver triglycerides (TG) content (% wet liver). Compared with the control group, fatty liver cows had greater concentrations of cholesterol and TG along with the typically vacuolated appearance and greater lipid droplets in the liver. Furthermore, fatty liver cows had greater mRNA and protein abundance related to hepatic lipid synthesis proteins sterol regulatory element binding proteins (SREBP-1c), long-chain acyl-CoA synthetase (ACSL), acyl-CoA carbrolase (ACC) and fatty acid synthase (FAS) and lipid transport proteins Liver fatty acid binding protein (L-FABP), apolipoprotein E (ApoE), low density lipoprotein receptor (LDLR) and microsomal TG transfer protein (MTTP) (p < 0.05). However, they had lower mRNA and protein abundance associated with fatty acid β-oxidation proteins SIRT1, peroxisome proliferator-activated receptor co-activator-1 (PGC-1α), peroxisome proliferator–activated receptor-α (PPARα), retinoid X receptor (RXRα), acyl-CoA 1 (ACO), carnitine palmitoyltransferase 1 (CPT1), carnitine palmitoyltransferase 2 (CPT2) and long- and medium-chain 3-hydroxyacyl-CoA dehydrogenases (LCAD) (p < 0.05). Additionally, mRNA abundance and enzyme activity of enzymes copper/zinc superoxide dismutase (Cu/Zn SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and manganese superoxide dismutase (Mn SOD) decreased and mRNA and protein abundance of p45 nuclear factor-erythroid 2 (p45 NF-E2)-related factor 1 (Nrf1), mitochondrial transcription factor A (TFAM) decreased (p < 0.05). Lower enzyme activities of SIRT1, PGC-1α, Cu/Zn SOD, CAT, GSH-Px, SREBP-1c and Mn SOD (p < 0.05) and concentration of reactive oxygen species (ROS) were observed in dairy cows with fatty liver. These results demonstrate that decreased SIRT1 associated with hepatic steatosis promotes hepatic fatty acid synthesis and inhibits fatty acid β-oxidation. Hence, SIRT1 may represent a novel therapeutic target for the treatment of the fatty liver disease in dairy cows.

Discovery of a promising agent IQZ23 for the treatment of obesity and related metabolic disorders

Discovery of novel anti-obesity agents is a challenging and promising research area. Based on our previous works, we synthesized 40 novel β-indoloquinazoline analogues by altering the skeleton and introducing preferential side chains, evaluated their lipid-lowering activity and summarized the structure-activity relationships. In combination with an evaluation of the lipid-lowering efficacies, AMP-dependent activated protein kinase (AMPK) activating ability and liver microsomal stability, compound 23 (named as IQZ23) was selected for further studies. IQZ23 exerted a high efficacy in decreasing the triglyceride level (EC₅₀ = 0.033 μM) in 3T3-L1 adipocytes. Mechanistic studies revealed the lipid-lowering activity of IQZ23 was dependent on the AMPK pathway by modulating ATP synthase activity. This activation was accompanied by mitochondrial biogenesis and oxidation capacity increased, and insulin sensitivity enhanced in pertinent cell models by various interventions. Correspondingly, IQZ23 (20 mg/kg, i.p.) treatment significantly reversed high fat and cholesterol diet (HFC)- induced body weight increases and accompanying clinical symptoms of obesity in mice but without indicative toxicity. These results indicate that IQZ23 could be a useful candidate for the treatment of obesity and related metabolic disorders.

Pyridocarbazole alkaloids from Ochrosia borbonica: lipid-lowering agents inhibit the cell proliferation and adipogenesis of 3T3-L1 adipocyte via intercalating into supercoiled DNA

Bioassay-guided fractionation of an ethanolic extract of Ochrosia borbonica led to the isolation of two known pyridocarbazole alkaloids, ellipticine (1) and 9-methoxyellipticine (2), and six known monoterpenoid indole alkaloids (3-8). Lipid-lowering assay in 3T3-L1 cell model revealed that 1 and 2 could significantly inhibit the lipid droplet formation (EC₅₀ = 0.41 and 0.92 μmol·L^-1, respectively) and lower triglyceride levels by 50%-60% at the concentration of 1 μmol·L^-1, being more potent than the positive drug luteolin (EC₅₀ = 2.63 μmol·L^-1). A mechanistic study indicated that 1 and 2 could intercalate into supercoiled DNA, which consequently inhibited the mitotic clonal expansion of 3T3-L1 cells at the early differentiation phase, leading to the retardance of following adipogenesis and lipogenesis. These findings suggest that 1 and 2 may serve as promising leads for further development of anti-obesity drugs.

Withania somnifera Extract Enhances Energy Expenditure via Improving Mitochondrial Function in Adipose Tissue and Skeletal Muscle

Withania somnifera (WS), commonly known as ashwagandha, possesses diverse biological functions. WS root has mainly been used as an herbal medicine to treat anxiety and was recently reported to have an anti-obesity effect, however, the mechanisms underlying its action remain to be explored. We hypothesized that WS exerts its anti-obesity effect by enhancing energy expenditure through improving the mitochondrial function of brown/beige adipocytes and skeletal muscle. Male C57BL/6J mice were fed a high-fat diet (HFD) containing 0.25% or 0.5% WS 70% ethanol extract (WSE) for 10 weeks. WSE (0.5%) supplementation significantly suppressed the increases in body weight and serum lipids, and lipid accumulation in the liver and adipose tissue induced by HFD. WSE supplementation increased oxygen consumption and enhanced mitochondrial activity in brown fat and skeletal muscle in the HFD-fed mice. In addition, it promoted browning of subcutaneous fat by increasing mitochondrial uncoupling protein 1 (UCP1) expression. Withaferin A (WFA), a major compound of WS, enhanced the differentiation of pre-adipocytes into beige adipocytes and oxygen consumption in C2C12 murine myoblasts. These results suggest that WSE ameliorates diet-induced obesity by enhancing energy expenditure via promoting mitochondrial function in adipose tissue and skeletal muscle, and WFA is a key regulator in this function.

Bouchardatine analogue alleviates non-alcoholic hepatic fatty liver disease/non-alcoholic steatohepatitis in high-fat fed mice by inhibiting ATP synthase activity

BACKGROUND AND PURPOSE

Non-alcoholic hepatic fatty liver disease (NAFLD) is a manifestation of the metabolic syndrome in the liver and non-alcoholic steatohepatitis (NASH) represents its advanced stage. R17 derived from bouchardatine, shows benefits in the metabolic syndrome, but has not been tested in the liver. The present study examined the pharmacological effects of R17 in a model of NAFLD/NASH and its mode of action.

EXPERIMENTAL APPROACH

The effects of R17 were examined in mice fed a high-fat (HF) diet to induce the pathological characteristics of NAFLD/NASH and in cultures of HuH7 cells. We used histological and immunohistochemical techniques along with western blotting and siRNA. Generation of ROS and apoptosis were measured.

KEY RESULTS

Administration of R17 (20 mg·kg^-1 , i.p. every other day) for 5 weeks reversed HF-induced hepatic triglyceride content, inflammation (inflammatory cytokines and macrophage numbers), injury (hepatocyte ballooning and apoptosis, plasma levels of alanine aminotransferase and aspartate aminotransferase), and fibrogenesis (collagen deposition and mRNA expression of fibrosis markers). In cultured cells, R17 reduced cell steatosis from both lipogenesis and fatty acid influx. The attenuated inflammation and cell injury were associated with inhibition of both endoplasmic reticulum (ER) stress and oxidative stress. Notably, R17 activated the liver kinase B1-AMP-activated protein kinase (AMPK) pathway by inhibiting activity of ATP synthase, rather than direct stimulation of AMPK.

CONCLUSION AND IMPLICATIONS

R17 has therapeutic potential for NAFLD/NASH. Its mode of action involves the elimination of ER and oxidative stresses, possibly via activating the LKB1-AMPK axis by inhibiting the activity of ATP synthase.

Bouchardatine suppresses rectal cancer in mice by disrupting its metabolic pathways via activating the SIRT1-PGC-1α-UCP2 axis

Cancer metabolism is an attractive target of the therapeutic strategy for cancer. The present study identified bouchardatine (Bou) as a potent suppressor of rectal cancer growth by cycle-arresting independent of apoptosis. In cultured HCT-116 rectal cancer cells, Bou increased glucose uptake/oxidation and capacity of mitochondrial oxidation. These effects were associated with an upregulation of uncoupling protein 2 (UCP2) and the activation of its upstream Sirtuin 1 (SIRT1)/(Liver kinase B1) LKB1- (Adenosine monophosphate-activated protein kinase) AMPK axis. The pivotal role of UCP2 in the cancer-suppressing effect was demonstrated by overexpressing UCP2 in HCT-116 cells with similar metabolic effects to those produced by Bou. Interestingly, Bou activated peroxisome proliferators activated receptor γ coactivator 1α (PGC-1α) and recruited it to the promoter of UCP2 in HCT-116 cells along with deacetylation (thus activation) by SIRT1. The requirement of SIRT1 for the cancer-suppressing effect through the PGC-1α-UCP2 was confirmed by the reciprocal responses to Bou in HCT-116 with defected and overexpressed SIRT1. Whereas knockdown, mutation or pharmacological inhibition of SIRT1 all abolished Bou-induced deacetylation/activation of PGC-1α, the opposing effects were observed after overexpressing SIRT1. In mice, administration of Bou (50 mg/kg) also suppressed the growth of rectal cancer associated with increases the UCP2 expression and mitochondria capacity in the tumor. Collectively, our findings suggest that Bou has a therapeutic potential for the treatment of rectal cancer by disrupting the metabolic path of cancer cells via activating the PGC-1α-UCP2 axis with SIRT1 as its primary target.

Euphorhelipanes A and B, Triglyceride-Lowering Euphorbia Diterpenoids with a Bicyclo[4.3.0]nonane Core from Euphorbia helioscopia

Euphorhelipanes A (1) and B (2), two Euphorbia diterpenoids with a new 4-(5,5-dimethylheptan-2-yl)-2,7-dimethylbicyclo[4.3.0]nonane skeleton, were isolated from a 95% ethanol extract of the whole plants of Euphorbia helioscopia. Their structures were elucidated by spectroscopic data analysis, quantum chemical calculations, and single-crystal X-ray diffraction data. Compounds 1 and 2 represent the first examples of Euphorbia diterpenoids with a 5/6 fused carbon ring system, and their plausible biosynthetic pathways originating from jatrophanes are proposed. Compounds 1 and 2 showed a triglyceride-lowering effect in oleic-acid-stimulated HuH7 cells at concentrations of 1-50 μM.

Transition metal-free synthesis of quinazolinones using dimethyl sulfoxide as a synthon

Biologically important quinazolinones have been synthesized from 2-aminobenzamides and DMSO.

Design, synthesis and biological evaluation of novel bouchardatine analogs as potential inhibitors of adipogenesis/lipogenesis in 3T3-L1 adipocytes

Inhibition of the differentiation of adipocytes and reduced lipid synthesis are efficacious approaches for treating obesity-related metabolic disorders. Bouchardatine (Bou) is a natural alkaloid that has been reported to moderately inhibit the differentiation of 3T3-L1 cells without inducing toxicity. To explore the importance of aldehyde group at 8a-position of Bou and optimize the activity, we synthesized 35 (31 novel) compounds by discarding or replacing aldehyde group with halogen and introducing different amine chains at 5-position of Bou. The lipid-lowering activity was evaluated using a cell-based screening system. The substitution of the group at the 8a-position of compounds was important for its lipid-lowering activity, and the SAR was discussed. The selective compound 6e showed a 93-fold increase in its lipid-lowering effect (EC₅₀ = 0.24 μM) compared with Bou (EC₅₀ ≈ 25 μM). Further mechanistic studies revealed that compound 6e activated AMP-activated protein kinase (AMPK) pathway and inhibited MCE activity to block cell proliferation and induce cell cycle arrest at the early stage of differentiation, thus decreasing the expression of adipogenic factors and fatty acid synthesis-related proteins.

Natural alkaloid bouchardatine ameliorates metabolic disorders in high-fat diet-fed mice by stimulating the sirtuin 1/liver kinase B-1/AMPK axis

BACKGROUND AND PURPOSE

Promoting energy metabolism is known to provide therapeutic effects for obesity and associated metabolic disorders. The present study evaluated the therapeutic effects of the newly identified bouchardatine (Bou) on obesity-associated metabolic disorders and the molecular mechanisms of these effects.

EXPERIMENTAL APPROACH

The molecular mode of action of Bou for its effects on lipid metabolism was first examined in 3T3-L1 adipocytes and HepG2 cells. This was followed by an evaluation of its metabolic effects in mice fed a high-fat diet for 16 weeks with Bou being administered in the last 5 weeks. Further mechanistic investigations were conducted in pertinent organs of the mice and relevant cell models.

KEY RESULTS

In 3T3-L1 adipocytes, Bou reduced lipid content and increased sirtuin 1 (SIRT1) activity to facilitate liver kinase B1 (LKB1) activation of AMPK. Chronic administration of Bou (50 mg∙kg^-1 every other day) in mice significantly attenuated high-fat diet-induced increases in body weight gain, dyslipidaemia and fatty liver without affecting food intake and no adverse effects were detected. These metabolic effects were associated with activation of the SIRT1-LKB1-AMPK signalling pathway in adipose tissue and liver. Of particular note, UCP1 expression and mitochondrial biogenesis were increased in both white and brown adipose tissues of Bou-treated mice. Incubation with Bou induced similar changes in primary brown adipocytes isolated from mice.

CONCLUSIONS AND IMPLICATIONS

Bou may have therapeutic potential for obesity-related metabolic diseases by increasing the capacity of energy expenditure in adipose tissues and liver through a mechanism involving the SIRT1-LKB1-AMPK axis.