Bitter melon extract attenuating hepatic steatosis may be mediated by FGF21 and AMPK/Sirt1 signaling in mice

Maternal exercise represses FGF21 via SIRT1 to improve the phenotypic transformation of vascular smooth muscle in hypertensive offspring

Maternal exercise during pregnancy is widely recognized as an effective means of promoting cardiovascular health in offspring. Few studies have explored how maternal exercise impacts vascular function and phenotypic switching in hypertensive offspring, despite the known involvement of vascular structural and functional remodeling in hypertension pathogenesis. Research indicates a significant relationship between elevated blood pressure and fibroblast growth factor 21 (FGF21) levels. It remains unclear whether maternal exercise during pregnancy can improve vascular function in hypertensive offspring by regulating FGF21 and its underlying mechanisms. In this study, pregnant spontaneously hypertensive rats and Wistar-Kyoto rats were randomly assigned to either a sedentary or exercise group. The exercise group underwent weightless swimming exercise from gestation day 1 (GD1) to GD20. The aim was to investigate the epigenetic modifications mediated by histone deacetylase sirtuin 1 (SIRT1) during the fetal period and the phenotypic changes in the mesenteric arteries (MAs) of hypertensive offspring. We found that maternal exercise significantly improved vascular remodeling in hypertensive offspring. Specifically, maternal exercise upregulated SIRT1 expression, which led to decreased H3K9ac (histone H3 lysine 9 acetylation) in the promoter region of the FGF21 gene. This epigenetic modification resulted in the transcriptional downregulation of FGF21 in the MAs of hypertensive fetuses. These results suggest that maternal exercise may lower blood pressure in hypertensive offspring by regulating deacetylation of the FGF21 gene promoter region through SIRT1, thereby reversing phenotypic switching and vascular structural remodeling.

Targeting AMPK related signaling pathways: A feasible approach for natural herbal medicines to intervene non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a metabolic disease characterized by abnormal deposition of lipid in hepatocytes. If not intervened in time, NAFLD may develop into liver fibrosis or liver cancer, and ultimately threatening life. NAFLD has complicated etiology and pathogenesis, and there are no effective therapeutic means and specific drugs. Currently, insulin sensitizers, lipid-lowering agents and hepatoprotective agents are often used for clinical intervention, but these drugs have obvious side effects, and their effectiveness and safety need to be further confirmed. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) plays a central role in maintaining energy homeostasis. Activated AMPK can enhance lipid degradation, alleviate insulin resistance (IR), suppress oxidative stress and inflammatory response, and regulate autophagy, thereby alleviating NAFLD. Natural herbal medicines have received extensive attention recently because of their regulatory effects on AMPK and low side effects. In this article, we reviewed the biologically active natural herbal medicines (such as natural herbal medicine formulas, extracts, polysaccharides, and monomers) that reported in recent years to treat NAFLD via regulating AMPK, which can serve as a foundation for subsequent development of candidate drugs for NAFLD.

Innovative treatments for obesity and NAFLD: A bibliometric study on antioxidants, herbs, phytochemicals, and natural compounds

The increasing scientific interest in antioxidants and naturally derived compounds as potential remedies for obesity and non-alcoholic fatty liver disease (NAFLD) has led to extensive research. The objective of this bibliometric analysis is to present an updated perspective on the topic of antioxidants, herbs, phytochemicals, and natural compounds, in the control of obesity and NAFLD, to identify new areas for future research. Publications from the years 2012-2022 were retrieved using the Scopus database. The research trends were analyzed using the Biblioshiny and VOSviewer tools. The field has seen a significant increase in research activity, as indicated by an annual growth rate of 10 % in the number of published manuscripts. China, Korea, and the USA emerged as the most prominent contributors in this specific field, supported by their notable volumes of publications and citations. The density analysis revealed that the most frequently occurring authors' keywords related to herbal species are, in rank order, Camelia sinensis, Momordica charantia, Curcuma longa, Ilex paraguariensis, Panax ginseng, Moringa oleifera, Garcinia cambogia, Garcinia mangostana, Zingiber officinale, and Cinnamomum verum. In the group of antioxidants, phytochemicals, and natural compounds, the top 10 were resveratrol, curcumin, quercetin, vitamin E, alpha-lipoic acid, vitamin C, chlorogenic acid, lycopene, fucoxanthin, and berberine. The co-occurrence analysis unveiled significant themes and potential trends, including a notable interest in the impact of herbal species, antioxidants, phytochemicals, and natural compounds on obesity and NAFLD through the modulation of the gut microbiome. Another recurring theme that arises, is the ongoing investigation of molecular targets that demonstrate anti-adipogenesis properties. The analysis presented in this study provides valuable insights for researchers investigating the efficacy of antioxidants, herbs, phytochemicals, and natural compounds in addressing obesity and NAFLD. Through the use of bibliometric methods, the study offers a comprehensive overview. Furthermore, the findings of this analysis can serve as a foundation for future research in this specific domain.

Dapagliflozin promotes browning of white adipose tissue through the FGFR1-LKB1-AMPK signaling pathway

BACKGROUND

Obesity is associated with a wide variety of metabolic disorders that impose significant burdens on patients and society. The "browning" phenomenon in white adipose tissue (WAT) has emerged as a promising therapeutic strategy to combat metabolic disturbances. However, though the anti-diabetic drug dapagliflozin (DAPA) is thought to promote "browning," the specific mechanism of this was previously unclear.

METHODS

In this study, C57BL/6 J male mice were used to establish an obesity model by high-fat diet feeding, and 3T3-L1 cells were used to induce mature adipocytes and to explore the role and mechanism of DAPA in "browning" through a combination of in vitro and in vivo experiments.

RESULTS

The results show that DAPA promotes WAT "browning" and improves metabolic disorders. Furthermore, we discovered that DAPA activated "browning" through the fibroblast growth factor receptors 1-liver kinase B1-adenosine monophosphate-activated protein kinase signaling pathway.

CONCLUSION

These findings provide a rational basis for the use of DAPA in treating obesity by promoting the browning of white adipose tissue.

PuRenDan alleviates type 2 diabetes mellitus symptoms by modulating the gut microbiota and its metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

PuRenDan (PRD) is a traditional Chinese medicine formula comprising five herbs that have been traditionally used to treat type 2 diabetes mellitus (T2DM). While PRD has been shown to be effective in treating T2DM in clinical and animal studies, the mechanisms by which it works on the gut microbiome and metabolites related to T2DM are not well understood.

AIM OF THE STUDY

The objective of this study was to partially elucidate the mechanism of PRD in treating T2DM through analyses of the gut microbiota metagenome and metabolome.

MATERIALS AND METHODS

Sprague-Dawley rats were fed high-fat diets (HFDs) and injected with low-dose streptozotocin (STZ) to replicate T2DM models. Then the therapeutic effects of PRD were evaluated by measuring clinical markers such as blood glucose, insulin resistance (IR), lipid metabolism biomarkers (total cholesterol, low-density lipoprotein, non-esterified fatty acids, and triglycerides), and inflammatory factors (tumor necrosis factor alpha, interleukin-6 [IL-6], interferon gamma, and IL-1β). Colon contents were collected, and metagenomics, combined with ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry metabolic profiling, was performed to evaluate the effects of T2DM and PRD on gut microbiota and its metabolites in rats. Spearman analysis was used to calculate the correlation coefficient among different microbiota, clinical indices, and metabolites.

RESULTS

PRD exhibited significant improvement in blood glucose and IR, and reduced serum levels of lipid metabolism biomarkers and inflammatory factors. Moreover, the diversity and abundance of gut microbiota undergo significant changes in rats with T2DM that PRD was able to reverse. The gut microbiota associated with T2DM including Rickettsiaceae bacterium 4572_127, Psychrobacter pasteurii, Parabacteroides sp. CAG409, and Paludibacter propionicigenes were identified. The gut microbiota most closely related to PRD were Prevotella sp. 10(H), Parabacteroides sp. SN4, Flavobacteriales bacterium, Bacteroides massiliensis, Alistipes indistinctus, and Ruminococcus flavefaciens. Additionally, PRD regulated the levels of gut microbiota metabolites including pantothenic acid, 1-Methylhistamine, and 1-Methylhistidine; these affected metabolites were involved in pantothenate and coenzyme A biosynthesis, histidine metabolism, and secondary bile acid biosynthesis. Correlation analysis illustrated a close relationship among gut microbiota, its metabolites, and T2DM-related indexes.

CONCLUSION

Our study provides insights into the gut microbiota and its metabolites of PRD therapy for T2DM. It clarifies the role of gut microbiota and the metabolites in the pathogenesis of T2DM, highlighting the potential of PRD for the treatment of this disease.

Biological Role and Related Natural Products of SIRT1 in Nonalcoholic Fatty Liver

Non-alcoholic fatty liver disease(NAFLD) is an umbrella term for a range of diseases ranging from hepatic fat accumulation and steatosis to non-alcoholic steatohepatitis (NASH) in the absence of excessive alcohol consumption and other definite liver damage factors. The incidence of NAFLD has increased significantly in recent years and will continue to grow in the coming decades. NAFLD has become a huge health problem and economic burden. SIRT1 is a member of Sirtuins, a group of highly conserved histone deacetylases regulated by NAD+, and plays a vital role in regulating cholesterol and lipid metabolism, improving oxidative stress, inflammation, and insulin resistance through deacetylating some downstream transcription factors and thus improving NAFLD. Although there are no currently approved drugs for treating NAFLD and some unresolved limitations in developing SIRT1 activators, SIRT1 holds promise as a proper therapeutic target for NAFLD and other metabolic diseases. In recent years, natural products have played an increasingly important role in drug development due to their safety and efficacy. It has been discovered that some natural products may be able to prevent and treat NAFLD by targeting SIRT1 and its related pathways. This paper reviews the mechanism of SIRT1 in the improvement of NALFD and the natural products that regulate NAFLD through SIRT1 and its associated pathways, and discusses the potential of SIRT1 as a therapeutic target for treating NAFLD and the effectiveness of these related natural products as clinical drugs or dietary supplements. These works may provide some new ideas and directions for finding new therapeutic targets for NAFLD and the development of anti-NAFLD drugs with good pharmacodynamic properties.

Momordica charantia Enhances Tendon Healing in Rats: An Experimental Study

Momordica charantia (MC) is a traditional plant widely used since ancient times for wound healing. This study evaluated its potential effects on tendon healing. Adult male Wistar albino rats (n = 32, 8 rats in each group) were anesthetized, and their Achilles tendons were prepared for surgical procedures. Group 1 (Cont = control group) was not subjected to any surgery and was used as a control group for baseline values. Group 2 (PR = primary repair group) underwent primary repair (PR) with a monofilament suture after a full-thickness incision of the Achilles tendon. A full-thickness incision was also made to the Achilles tendon of group 3 (CT = collagen tube-administered group), followed by PR and collagen tube insertion. In group 4 (MC = M. charantia-administered group), 1 mL of MC extract was applied locally on the collagen tube in addition to the surgical procedure applied to group 3. The Achilles tendons were excised on the postoperative 40th day and examined stereologically, histologically, and bioinformatically. Data showed that the total volume of the collagen fibers was higher in MC and CT groups than in the PR group. The total volume of the tendon was decreased in MC and CT groups than in the Cont group. The ratios between the volumes of the collagen fibers and total tendon in the MC and CT groups were significantly different from PR, but not different from the Cont group. Additionally, MC improved tenoblastic activity, collagen production, and neovascularization. Bioinformatic interactions showed that the proteases of MC could trigger the signals playing a role on vasculogenesis, reducing inflammation, and contributing to tenoblast activation and collagen remodeling. MC extract ameliorates the healing of injured tendon and can provide satisfactory tendon repair. Further works are recommended to explore the healing capacity of MC.

Fibroblast Growth Factor-21 as a Potential Therapeutic Target of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent disease without any approved treatment to-date despite intensive research efforts by researchers and pharmaceutical industry. Fibroblast growth factor (FGF)-21 has been gaining increasing attention as a possible contributing factor and thus therapeutic target for obesity-related metabolic disorders, including NAFLD, mainly due to its effects on lipid and carbohydrate metabolism. Most animal and human observational studies have shown higher FGF-21 concentrations in NAFLD than non-NAFLD, implying that FGF-21 may be increased to counteract hepatic steatosis and inflammation. However, although Mendelian Randomization studies have revealed that variations of FGF-21 levels within the physiological range may have effects in hyperlipidemia and possibly nonalcoholic steatohepatitis, they also indicate that FGF-21, in physiological concentrations, may fail to reverse NAFLD and may not be able to control obesity and other diseases, indicating a state of FGF-21 resistance or insensitivity that could not respond to administration of FGF-21 in supraphysiological concentrations. Interventional studies with FGF-21 analogs (eg, pegbelfermin, efruxifermin, BOS-580) in humans have provided some favorable results in Phase 1 and Phase 2 studies. However, the definite effect of FGF-21 on NAFLD may be clarified after the completion of the ongoing clinical trials with paired liver biopsies and histological endpoints. The aim of this review is to critically summarize experimental and clinical data of FGF-21 in NAFLD, in an attempt to highlight existing knowledge and areas of uncertainty, and subsequently, to focus on the potential therapeutic effects of FGF-21 and its analogs in NAFLD.

Emerging roles of fibroblast growth factor 21 in critical disease

In spite of the great progress in the management of critical diseases in recent years, its associated prevalence and mortality of multiple organ failure still remain high. As an endocrine hormone, fibroblast growth factor 21 (FGF21) functions to maintain homeostasis in the whole body. Recent studies have proved that FGF21 has promising potential effects in critical diseases. FGF21 has also been found to have a close relationship with the progression of critical diseases and has a great predictive function for organ failure. The level of FGF21 was elevated in both mouse models and human patients with sepsis or other critical illnesses. Moreover, it is a promising biomarker and has certain therapeutic roles in some critical diseases. We focus on the emerging roles of FGF21 and its potential effects in critical diseases including acute lung injury/acute respiratory distress syndrome (ALI/ARDS), acute myocardial injury (AMI), acute kidney injury (AKI), sepsis, and liver failure in this review. FGF21 has high application value and is worth further studying. Focusing on FGF21 may provide a new perspective for the management of the critical diseases.

Activating Effects of the Bioactive Compounds From Coffee By-Products on FGF21 Signaling Modulate Hepatic Mitochondrial Bioenergetics and Energy Metabolism in vitro

Coffee by-products contain bioactive compounds that have been shown to have the capacity to modulate human metabolism. The goal of this study was to investigate the effects of the main bioactive compounds in coffee by-products and two aqueous extracts from the coffee husk and silverskin on the activation of fibroblast growth factor 21 (FGF21) signaling and the subsequent regulation of mitochondrial bioenergetics and lipid and glucose metabolism. HepG2 cells treated with palmitic acid (PA) were used in a non-alcoholic fatty liver disease (NAFLD) cell model. The bioactive compounds from coffee by-products (50 μmol L⁻¹) and the aqueous extracts from the coffee silverskin and coffee husk (100 μg mL⁻¹) increased ERK1/2 phosphorylation and the secretion of FGF21 (1.3 to 1.9-fold). Coffee by-products' bioactive compounds counteracted inflammation and PA-triggered lipotoxicity. Oxidative stress markers (ROS, mitochondrial superoxide, and NADPH oxidase) and the activity of antioxidant enzymes (superoxide dismutase and catalase) were modulated through the activation of Nrf2 signaling. Mitochondrial bioenergetics were regulated by enhancing respiration and ATP production via PGC-1α, and the expression of oxidative phosphorylation complexes increased. Coffee by-products' bioactive compounds decreased lipid accumulation (23–41%) and fatty acid synthase activity (32–65%) and triggered carnitine palmitoyltransferase-1 activity (1.3 to 1.7-fold) by activating AMPK and SREBP-1c pathways. The GLUT2 expression and glucose uptake were increased (58–111%), followed by a promoted glucokinase activity (55–122%), while glucose production and phosphoenolpyruvate carboxykinase activity were reduced due to IRS-1/Akt1 regulation. The bioactive compounds from coffee by-products, primarily chlorogenic and protocatechuic acids, could regulate hepatic mitochondrial function and lipid and glucose metabolism by activating FGF21 and related signaling cascades.

Purendan alleviates non-alcoholic fatty liver disease in aged type 2 diabetic rats via regulating mTOR/S6K1/SREBP-1c signaling pathway

Older people are more likely to develop insulin resistance and lipid metabolism disorders. Purendan (PRD) is a clinically verified traditional Chinese medicine compound, which plays an obvious role in regulating lipid metabolism disorder and improving insulin sensitivity. Our study aimed to investigate the efficacy and mechanism of PRD on aged type 2 diabetes mellitus (T2DM) complicated with non-alcoholic fatty liver disease (NAFLD) rats. Sprague-Dawley rats (13 months) were fed with high-fat diet (HFD) and injected with low-dose STZ to replicate T2DM model. PRD was treated at three concentrations with metformin as a positive control. After administration, blood and liver tissue samples were collected to measure glucose metabolism indexes such as serum glucose and insulin, as well as lipid metabolism indexes such as TC, TG, LDL, HDL and FFA. Liver fat accumulation was observed by HE staining and oil red O staining. And protein expression levels of mTOR, p-mTOR, S6K1, p-S6K1 and SREBP-1c were detected by western blot. After PRD treatment, not only the insulin sensitivity and insulin resistance were significantly improved, but also the TC, TG, LDL, FFA, AST and ALT in serum and the lipid accumulation in liver tissue were significantly decreased. Moreover, PRD significantly down-regulated the expression of p-mTOR, p-S6K1 and SREBP-1c in liver tissues. In conclusion, PRD can alleviate NAFLD in aged T2DM rats by inhibiting the mTOR /S6K1/ SREBP-1c pathway.

FGF21 alleviates acute liver injury by inducing the SIRT1-autophagy signalling pathway

Liver injury can lead to different hepatic diseases, which are the mainly causes of high global mortality and morbidity. Autophagy and Sirtuin type 1 (SIRT1) have been shown protective effects in response to liver injury. Previous studies have showed that Fibroblast growth factor 21 (FGF21) could alleviate acute liver injury (ALI), but the mechanism remains unclear. Here, we verified the relationship among FGF21, autophagy and SIRT1 in carbon tetrachloride (CCl₄)‐induced ALI. We established CCl₄‐induced ALI models in C57BL/6 mice and the L02 cell line. The results showed that FGF21 was robustly induced in response to stress during the development of ALI. After exogenous FGF21 treatment in ALI models, liver damage in ALI mice was significantly reduced, as well as serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Consistently, FGF21 also greatly reduced the levels of ALT, AST, pro‐inflammatory cytokines interleukin 6 (IL6) and tumour necrosis factor‐alpha (TNFα) in ALI cell lines. Mechanistically, exogenous FGF21 treatment efficiently upregulated the expression of autophagy marker microtubule‐associated protein light chain‐3 beta (LC3 II) and autophagy key molecule coiled‐coil myosin‐like BCL2‐interacting protein (Beclin1), which was accompanied by alleviating hepatotoxicity in CCl₄‐treated wild‐type mice. Then, we examined how FGF21 induced autophagy expression and found that SIRT1 was also upregulated by FGF21 treatment. To further verify our results, we constructed an anti‐SIRT1 lentit‐RNAi to inhibit SIRT1 expression in mice and L02 cells, which reversed the protective effect of FGF21 on ALI. In summary, these results indicate that FGF21 alleviates ALI by enhancing SIRT1‐mediated autophagy.

AMPK activators for the prevention and treatment of neurodegenerative diseases

INTRODUCTION

As the global population ages at an unprecedented rate, the burden of neurodegenerative diseases is expected to grow. Given the profound impact illness like dementia exert on individuals and society writ large, researchers, physicians, and scientific organizations have called for increased investigation into their treatment and prevention. Both metformin and aspirin have been associated with improved cognitive outcomes. These agents are related in their ability to stimulate AMP kinase (AMPK). Momordica charantia, another AMPK activator, is a component of traditional medicines and a novel agent for the treatment of cancer. It is also being evaluated as a nootropic agent.

AREAS COVERED

This article is a comprehensive review which examines the role of AMPK activation in neuroprotection and the role that AMPK activators may have in the management of dementia and cognitive impairment. It evaluates the interaction of metformin, aspirin, and Momordica charantia, with AMPK, and reviews the literature characterizing these agents' impact on neurodegeneration.

EXPERT OPINION

We suggest that AMPK activators should be considered for the treatment and prevention of neurodegenerative diseases. We identify multiple areas of future investigation which may have a profound impact on patients worldwide.

Advances in Biological Functions and Clinical Studies of FGF21

Fibroblast growth factor 21 (FGF21) regulates many crucial biological processes in human and mammals, particularly metabolic modulation and protective effect after injury. Therefore, determining complex regulatory mechanisms and elucidating the signaling pathway may greatly promote the prevention, diagnosis, and treatment of related injury and metabolic diseases. This review focused on the metabolic modulation and protective effect of FGF21 and summarized the molecular mechanisms and clinical research developments.

mcIRBP-19 of Bitter Melon Peptide Effectively Regulates Diabetes Mellitus (DM) Patients' Blood Sugar Levels

This study was conducted to test the effectiveness of a particular bitter melon peptide (BMP), with a specific sequence of 19 amino acids (mcIRBP-19), in regulating diabetic patients' blood glucose. In order to test the product with the specially processed BMP, a total of 142 diabetic patients were solicited as study subjects, of which 64 were assigned to an experiment group and 78 to a control group. Biochemical data were compared with a paired t-test to verify the significance of changes over different time periods. The clinical results showed that BMP started to improve the subjects' glycated hemoglobin (HbA1c) levels at the end of the second month (T2), with mean values being significantly lowered from 7.8 ± 1.4% (T0) to 7.5 ± 1.4% (T2) (p = 0.004). The values reduced continuously, eventually reaching 7.4 ± 1.1% (p = 0.000) at the end of the experiment (T3). HbA1c levels for the control group were 7.5 ± 1.2% in T0 and 7.5 ± 1.1% (T3), and not significantly different (p = 0.852) over the same period. This study provides clinical evidence that helps to verify the effectiveness of the new BMP product in regulating diabetic patients' blood sugar levels.

Bitter melon fruit extract has a hypoglycemic effect and reduces hepatic lipid accumulation in ob/ob mice

Bitter melon (Momordica charantia L.) is a vegetable and has been used as traditional medicine. Recently, we reported that bitter melon fruit extracts and its ethyl acetate (EtOAc)-soluble fraction markedly suppressed the expression of proinflammatory genes, including the inducible nitric oxide synthase gene. However, it is unclear whether bitter melon exhibits antidiabetic effects. In this study, we showed that cucurbitacin B, a cucurbitane-type triterpenoid, was present in an EtOAc-soluble fraction and suppressed nitric oxide production in hepatocytes. When the EtOAc-soluble fraction was administered for 7 days to ob/ob mice, a type 2 diabetes mellitus model, the mice fed with this fraction exhibited a significant decrease in body weight and blood glucose concentrations compared with the mice fed without the fraction. The administration of the fraction resulted in significant increases in serum insulin concentrations and the levels of both insulin receptor mRNA and protein in the ob/ob mouse liver. The EtOAc-soluble fraction decreased the interleukin-1β mRNA expression, as well as hepatic lipid accumulation in hepatocytes. Taken together, these results indicate that administration of an EtOAc-soluble fraction improved hyperglycemia and hepatic steatosis, suggesting that this fraction may be responsible for both the antidiabetic and anti-inflammatory effects of bitter melon fruit.

Lyophilized Maqui (Aristotelia chilensis) Berry Induces Browning in the Subcutaneous White Adipose Tissue and Ameliorates the Insulin Resistance in High Fat Diet-Induced Obese Mice

Maqui (Aristotelia Chilensis) berry features a unique profile of anthocyanidins that includes high amounts of delphinidin-3-O-sambubioside-5-O-glucoside and delphinidin-3-O-sambubioside and has shown positive effects on fasting glucose and insulin levels in humans and murine models of type 2 diabetes and obesity. The molecular mechanisms underlying the impact of maqui on the onset and development of the obese phenotype and insulin resistance was investigated in high fat diet-induced obese mice supplemented with a lyophilized maqui berry. Maqui-dietary supplemented animals showed better insulin response and decreased weight gain but also a differential expression of genes involved in de novo lipogenesis, fatty acid oxidation, multilocular lipid droplet formation and thermogenesis in subcutaneous white adipose tissue (scWAT). These changes correlated with an increased expression of the carbohydrate response element binding protein b (Chrebpb), the sterol regulatory binding protein 1c (Srebp1c) and Cellular repressor of adenovirus early region 1A-stimulated genes 1 (Creg1) and an improvement in the fibroblast growth factor 21 (FGF21) signaling. Our evidence suggests that maqui dietary supplementation activates the induction of fuel storage and thermogenesis characteristic of a brown-like phenotype in scWAT and counteracts the unhealthy metabolic impact of an HFD. This induction constitutes a putative strategy to prevent/treat diet-induced obesity and its associated comorbidities.

Activation of AMPK by Medicinal Plants and Natural Products: Its Role in Type 2 Diabetes Mellitus

Type-2 Diabetes (T2D) is a metabolic disease characterized by permanent hyperglycemia, whose development can be prevented or delayed by using therapeutic agents and implementing lifestyle changes. Some therapeutic alternatives include regulation of glycemia through modulation of different mediators and enzymes, such as AMP-activated protein kinase (AMPK), a highly relevant cellular energy sensor for metabolic homeostasis regulation, with particular relevance in the modulation of liver and muscle insulin sensitivity. This makes it a potential therapeutic target for antidiabetic drugs. In fact, some of them are standard drugs used for treatment of T2D, such as biguanides and thiazolidindiones. In this review, we compile the principal natural products that are activators of AMPK and their effect on glucose metabolism, which could make them candidates as future antidiabetic agents. Phenolics such as flavonoids and resveratrol, alkaloids such as berberine, and some saponins are potential natural activators of AMPK with a potential future as antidiabetic drugs.

In vitro and in silico elucidation of antidiabetic and anti-inflammatory activities of bioactive compounds from Momordica charantia L

Bitter melon (Momordica charantia) has been used to manage diabetes and related conditions in various parts of the world. In the present study, ten compounds were isolated from acetone and methanol extracts of bitter melon. The chemical structures of compounds were unambiguously elucidated by 1D, 2D NMR, and high-resolution mass spectra. Identified compounds 1-7 exhibited significant inhibition of α-amylase and moderate inhibition of α-glucosidase activities. Momordicoside G and gentisic acid 5-O-β-d-xyloside showed the highest inhibition of α-amylase (70.5%), and α-glucosidase (56.4%), respectively. Furthermore, molecular docking studies of isolated compounds 1-7 were able to bind to the active sites of both enzymes. Additionally, the isolated compounds 1-7 significantly attenuated lipopolysaccharide (LPS)-induced inflammation, downregulating the expression of pro-inflammatory markers NF-κB, INOS, IL-6, IL-1β, TNF-α, and Cox-2 in murine macrophage RAW 264.7 cells. One phenolic derivative, gentisic acid 5-O-β-d-xyloside, was isolated and identified for the first time from bitter melon, and significantly suppressed the expression of Cox-2 and IL-6 compared to the LPS-treated group. α-Amylase and α-glucosidase are targets of anti-diabetes drugs, our findings suggest that compounds purified from bitter melon may have potential to use as functional food ingredients for the prevention of type 2 diabetes and related inflammatory conditions.

Fibroblast Growth Factor 21 Stimulates Pancreatic Islet Autophagy via Inhibition of AMPK-mTOR Signaling

Background: Islet autophagy plays a role in glucose/lipid metabolism in type 2 diabetes mellitus. Meanwhile, fibroblast growth factor 21 (FGF21) has been found to regulate insulin sensitivity and glucose homeostasis. Whether FGF21 induces islet autophagy, remains to be elucidated. This study aimed to explore the physiological roles and signaling pathways involved in FGF21-stimulated islet autophagy under glucolipotoxic conditions. Methods: C57/BL6J mice were fed a standard diet or high-fat diet (HFD) for 12 weeks, and islets were isolated from normal and FGF21 knockout (KO) mice. Isolated islets and INS-1E cells were exposed to normal and high-concentration glucose and palmitic acid with/without FGF21 or AMPK inhibitor compound C. Real-time PCR, Western blot and immunohistochemistry/transmission electron microscopy were performed for the expression of targeted genes/proteins. Results: HFD-treated mice showed increases in fasting plasma glucose, body weight and impaired glucose tolerance; islet protein expression of FGF21 was induced after HFD treatment. Protein expression levels of FGF21 and LC3-II (autophagy marker) were induced in mouse islets treated with high concentrations of palmitic acid and glucose, while phosphorylation of AMPK was reduced, compared with controls. In addition, induction of LC3-II protein expression was reduced in islets isolated from FGF21 KO mice. Furthermore, exogenous administration of FGF21 diminished phosphorylation of AMPK and stimulated protein expression of LC3-II. Consistently, compound C significantly induced increased expression of LC3-II protein. Conclusions: Our data indicate that glucolipotoxicity-induced FGF21 activation mediates islet autophagy via AMPK inhibition, and further consolidate the evidence for the FGF21/analog being a pharmacotherapeutic target for obesity and its related T2DM.

Cucurbitane triterpenoids from the fruit of Momordica charantia L. and their anti-hepatic fibrosis and anti-hepatoma activities

Momordica charantia L. (Cucurbitaceae) is a popular vegetable and traditional folk medicine, that has been used for hundreds of years. In this study, three undescribed cucurbitane-type triterpene glycosides furpyronecucurbitane A, goyaglycoside I and charantagenin F along with nine known compounds were isolated from the immature fruit of Momordica charantia L. Their structures were identified on the basis of extensive 1D, 2D NMR and HRESIMS spectroscopy analysis. All isolated compounds were examined for their anti-hepatic fibrosis activity against murine hepatic stellate cells (t-HSC/Cl-6) and anti-hepatoma activity against two kinds of liver cancer cell lines (HepG2 and Hep3B). Among them, karaviloside III exhibited excellent inhibitory activity against activated t-HSC/Cl-6 cells and cytotoxic activity against Hep3B and HepG2 cell lines with IC₅₀ values of 3.74 ± 0.13, 16.68 ± 2.07 and 4.12 ± 0.36 μM, respectively, which may potential to be developed as a chemotherapy agent for treatment hepatic fibrosis or carcinoma and protection against both diseases.

Isoquercetin Improves Hepatic Lipid Accumulation by Activating AMPK Pathway and Suppressing TGF-β Signaling on an HFD-Induced Nonalcoholic Fatty Liver Disease Rat Model

Isoquercetin (IQ), a glucoside derivative of quercetin, has been reported to have beneficial effects in nonalcoholic fatty liver disease (NAFLD). In this study, we investigated the potential improvement of IQ in liver lipid accumulation, inflammation, oxidative condition, and activation in Kupffer cells (KCs) on a high-fat diet (HFD) induced NAFLD models. Male Sprague-Dawley (SD) rats were induced by HFD, lipopolysaccharides/free fatty acids (LPS/FFA) induced co-culture cells model between primary hepatocytes and Kupffer cells was used to test the effects and the underlying mechanism of IQ. Molecular docking was performed to predict the potential target of IQ. Significant effects of IQ were found on reduced lipid accumulation, inflammation, and oxidative stress. In addition, AMP-activated protein kinase (AMPK) pathway was activated by IQ, and is plays an important role in lipid regulation. Meanwhile, IQ reversed the increase of activated KCs which caused by lipid overload, and also suppression of Transforming growth factor beta (TGF-β) signaling by TGF-β Recptor-1 and SMAD2/3 signaling. Finally, TGF-βR1 and TGF-βR2 were both found may involve in the mechanism of IQ. IQ can improve hepatic lipid accumulation and decrease inflammation and oxidative stress by its activating AMPK pathway and suppressing TGF-β signaling to alleviate NAFLD.

Treatment of Diabetic Mice with a Combination of Ketogenic Diet and Aerobic Exercise via Modulations of PPARs Gene Programs

Type 2 diabetes is a prevalent chronic disease arising as a serious public health problem worldwide. Diet intervention is considered to be a critical strategy in glycemic control of diabetic patients. Recently, the low-carbohydrate ketogenic diet is shown to be effective in glycemic control and weight loss. However, hepatic lipid accumulation could be observed in mice treated with ketogenic diet. On the other hand, exercise is a well-known approach for treating nonalcoholic fatty liver disease. We thus hypothesize that the combination of ketogenic diet and exercise could improve insulin sensitivity, while minimizing adverse effect of hepatic steatosis. In order to test this hypothesis, we established diabetic mice model with streptozotocin (STZ) and divided them into control group, ketogenic diet group, and ketogenic diet with aerobic exercise group. We found that after six weeks of intervention, mice treated with ketogenic diet and ketogenic diet combined with exercise both have lower body weights, HbAlc level, HOMA index, and improvements in insulin sensitivity, compared with diabetes group. In addition, mice in ketogenic diet intervention exhibited hepatic steatosis shown by serum and hepatic parameters, as well as histochemistry staining in the liver, which could be largely relieved by exercise. Furthermore, gene analysis revealed that ketogenic diet in combination with exercise reduced PPARγ and lipid synthetic genes, as well as enhancing PPARα and lipid β-oxidation gene program in the liver compared to those in ketogenic diet without exercise. Overall, the present study demonstrated that the combination of ketogenic diet and a moderate-intensity aerobic exercise intervention improved insulin sensitivity in diabetic mice, while avoiding hepatic steatosis, which provided a novel strategy in the combat of diabetes.

Mediterranean Tomato-Based Sofrito Sauce Improves Fibroblast Growth Factor 21 (FGF21) Signaling in White Adipose Tissue of Obese ZUCKER Rats

SCOPE

Obesity is a fibroblast growth factor 21 (FGF21)-resistant state. Since FGF21 production and signaling are regulated by some bioactive dietary compounds, we analyze the impact of Mediterranean tomato-based sofrito sauce on: (i) the FGF21 expression and signaling in visceral white adipose tissue (vWAT), and (ii) the insulin sensitivity of obese Zucker rats (OZR).

METHODS AND RESULTS

OZR are fed with a sofrito-supplemented diet or control diet. Insulin sensitivity and FGF21 signaling are determined. We observed that sofrito is able to improve the responsiveness to both hormones in obese rats. Sofrito-supplemented diet increases FGF21 signaling in vWAT by inducing the expression of the FGF receptors (FGFR1 and FGFR4) that promotes the expression of canonical target genes, like Egr-1, c-Fos and uncoupling protein 1 (Ucp1).

CONCLUSIONS

A sofrito-supplemented diet improves insulin and FGF21 sensitivity in OZR, explaining part of sofrito's healthy effects on glucose metabolism. In addition, induction of UCP1 and the unchanged body weight despite the hyperphagic behavior of the sofrito-fed rats suggests that the increase in FGF21 signaling correlates with an increase in energy expenditure (EE). Further studies in humans may help to understand whether sofrito consumption increases the EE in obese individuals.

Bitter Melon (Momordica charantia) Extract Inhibits Tumorigenicity and Overcomes Cisplatin-Resistance in Ovarian Cancer Cells Through Targeting AMPK Signaling Cascade

Objective Acquired chemoresistance is a major obstacle in the clinical management of ovarian cancer. Therefore, searching for alternative therapeutic modalities is urgently needed. Bitter melon (Momordica charantia) is a traditional dietary fruit, but its extract also shows potential medicinal values in human diabetes and cancers. Here, we sought to investigate the extract of bitter melon (BME) in antitumorigenic and cisplatin-induced cytotoxicity in ovarian cancer cells.

METHODS

Three varieties of bitter melon were used to prepare the BME. Ovarian cancer cell lines, human immortalized epithelial ovarian cells (HOSEs), and nude mice were used to evaluate the cell cytotoxicity, cisplatin resistance, and tumor inhibitory effect of BME. The molecular mechanism of BME was examined by Western blotting.

RESULTS

Cotreatment with BME and cisplatin markedly attenuated tumor growth in vitro and in vivo in a mouse xenograft model, whereas there was no observable toxicity in HOSEs or in nude mice in vivo Interestingly, the antitumorigenic effects of BME varied with different varieties of bitter melon, suggesting that the amount of antitumorigenic substances may vary. Studies of the molecular mechanism demonstrated that BME activates AMP-activated protein kinase (AMPK) in an AMP-independent but CaMKK (Ca(2+)/calmodulin-dependent protein kinase)-dependent manner, exerting anticancer effects through activation of AMPK and suppression of the mTOR/p70S6K and/or the AKT/ERK/FOXM1 (Forkhead Box M1) signaling cascade.

CONCLUSION

BME functions as a natural AMPK activator in the inhibition of ovarian cancer cell growth and might be useful as a supplement to improve the efficacy of cisplatin-based chemotherapy in ovarian cancer.

Nutritional regulation of fibroblast growth factor 21: from macronutrients to bioactive dietary compounds

Obesity is a worldwide health problem mainly due to its associated comorbidities. Fibroblast growth factor 21 (FGF21) is a peptide hormone involved in metabolic homeostasis in healthy individuals and considered a promising therapeutic candidate for the treatment of obesity. FGF21 is predominantly produced by the liver but also by other tissues, such as white adipose tissue (WAT), brown adipose tissue (BAT), skeletal muscle, and pancreas in response to different stimuli such as cold and different nutritional challenges that include fasting, high-fat diets (HFDs), ketogenic diets, some amino acid-deficient diets, low protein diets, high carbohydrate diets or specific dietary bioactive compounds. Its target tissues are essentially WAT, BAT, skeletal muscle, heart and brain. The effects of FGF21 in extra hepatic tissues occur through the fibroblast growth factor receptor (FGFR)-1c together with the co-receptor β-klotho (KLB). Mechanistically, FGF21 interacts directly with the extracellular domain of the membrane bound cofactor KLB in the FGF21- KLB-FGFR complex to activate FGFR substrate 2α and ERK1/2 phosphorylation. Mice lacking KLB are resistant to both acute and chronic effects of FGF21. Moreover, the acute insulin sensitizing effects of FGF21 are also absent in mice with specific deletion of adipose KLB or FGFR1. Most of the data show that pharmacological administration of FGF21 has metabolic beneficial effects. The objective of this review is to compile existing information about the mechanisms that could allow the control of endogenous FGF21 levels in order to obtain the beneficial metabolic effects of FGF21 by inducing its production instead of doing it by pharmacological administration.

Overexpression of β-Klotho in Adipose Tissue Sensitizes Male Mice to Endogenous FGF21 and Provides Protection From Diet-Induced Obesity

The endocrine hormone fibroblast growth factor 21 (FGF21) is induced in the adaptive response to nutrient deprivation, where it serves to regulate the integrated response to fasting via its primary receptor complex, FGF receptor 1 coupled with the cofactor β-klotho (KLB) in target tissues. Curiously, endogenous FGF21 levels are also elevated in preclinical models of obesity and in obese/diabetic individuals. In addition to higher FGF21 levels, reduced KLB expression in liver and adipose tissue has been noted in these same individuals, suggesting that obesity may represent an FGF21 resistant state. To explore the contribution of tissue-specific KLB levels to endogenous FGF21 activity, in both fasting and high-fat diet feeding conditions, we generated animals overexpressing KLB in liver (LKLBOE) or adipose (ATKLBOE). Supportive of tissue-specific partitioning of FGF21 action, after chronic high-fat feeding, ATKLBOE mice gained significantly less weight than WT. Reduced weight gain was associated with elevated caloric expenditure, accompanied by a reduced respiratory exchange ratio and lower plasma free fatty acids levels, suggestive of augmented lipid metabolism. In contrast, LKLBOE had no effect on body weight but did reduce plasma cholesterol. The metabolic response to fasting was enhanced in LKLBOE mice, evidenced by increased ketone production, whereas no changes in this were noted in ATKLBOE mice. Taken together, these data provide further support that specific effects of FGF21 are mediated via engagement of distinct target organs. Furthermore, enhancing KLB expression in adipose may sensitize to endogenous FGF21, thus representing a novel strategy to combat metabolic disease.

Inhibition of HMGB1 release via salvianolic acid B-mediated SIRT1 up-regulation protects rats against non-alcoholic fatty liver disease

The inflammatory mediator high-mobility group box 1 (HMGB1) plays a critical role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the regulation of HMGB1 in NAFLD, particularly through sirtuin 1 (SIRT1), remains unclear. In this study, we investigated the role of SIRT1-mediated inhibition of HMGB1 release in NAFLD and the effect of salvianolic acid B (SalB), which is a water-soluble phenolic acid extracted from Radix Salvia miltiorrhiza, on NAFLD through SIRT1/HMGB1 signaling. In vivo, SalB treatment significantly attenuated high-fat diet (HFD)-induced liver damage, hepatic steatosis, and inflammation. Importantly, SalB significantly inhibited HMGB1 nuclear translocation and release, accompanied by SIRT1 elevation. In HepG2 cells, palmitic acid (PA)-induced pro-inflammatory cytokines release were blocked by HMGB1 small interfering RNA (siRNA) transfection. Moreover, pharmacological SIRT1 inhibition by Ex527 induced HMGB1 translocation and release, whereas SIRT1 activation by resveratrol or SalB reversed this trend. SIRT1 siRNA abrogated the SalB-mediated inhibition of HMGB1 acetylation and release, suggesting that SalB-mediated protection occurs by SIRT1 targeting HMGB1 for deacetylation. We are the first to demonstrate that the SIRT1/HMGB1 pathway is a key therapeutic target for controlling NAFLD inflammation and that SalB confers protection against HFD- and PA-induced hepatic steatosis and inflammation through SIRT1-mediated HMGB1 deacetylation.

Beneficial role of bitter melon supplementation in obesity and related complications in metabolic syndrome

Diabetes, obesity, and metabolic syndrome are becoming epidemic both in developed and developing countries in recent years. Complementary and alternative medicines have been used since ancient era for the treatment of diabetes and cardiovascular diseases. Bitter melon is widely used as vegetables in daily food in Bangladesh and several other countries in Asia. The fruits extract of bitter melon showed strong antioxidant and hypoglycemic activities in experimental condition both in vivo and in vitro. Recent scientific evaluation of this plant extracts also showed potential therapeutic benefit in diabetes and obesity related metabolic dysfunction in experimental animals and clinical studies. These beneficial effects are mediated probably by inducing lipid and fat metabolizing gene expression and increasing the function of AMPK and PPARs, and so forth. This review will thus focus on the recent findings on beneficial effect of Momordica charantia extracts on metabolic syndrome and discuss its potential mechanism of actions.

Estrogen and mitochondria function in cardiorenal metabolic syndrome

The cardiorenal metabolic syndrome (CRS) consists of a constellation of cardiac, renal, and metabolic disorders including insulin resistance (IR), obesity, metabolic dyslipidemia, high-blood pressure, and evidence of early cardiac and renal disease. Mitochondria dysfunction often occurs in the CRS, and this dysfunction is promoted by excess reactive oxygen species, genetic factors, IR, aging, and altered mitochondrial biogenesis. Recently, it has been shown that there are important sex-related differences in mitochondria function and metabolic, cardiovascular, and renal components. Sex differences in the CRS have mainly been attributed to the estrogen's effects that are mainly mediated by estrogen receptor (ER) α, ERβ, and G-protein coupled receptor 30. In this review, we discuss the effects of estrogen on the mitochondrial function, insulin metabolic signaling, glucose transport, lipid metabolism, and inflammatory responses from liver, pancreatic β cells, adipocytes, skeletal muscle, and cardiovascular tissue.