S-allyl cysteine attenuates free fatty acid-induced lipogenesis in human HepG2 cells through activation of the AMP-activated protein kinase-dependent pathway

Chlormequat chloride induces hepatic steatosis by promoting mTOR/SREBP1 mediated lipogenesis via AMPK inhibition

Chlormequat chloride (CCC), a widely used plant growth regulator, is a choline analogue that has been shown to have endocrine-disrupting effects. Previous studies have shown that maternal exposure to CCC could induce hyperlipidemia and growth disruption in rat offspring. This study aims to further investigate the effects of peripubertal exposure to CCC on pubertal development and lipid homeostasis, as well as the underlying mechanisms. In vivo, male weanling rats were exposed to CCC (0, 20, 75 and 200 mg/kg bw/day) from post-natal day 21-60 via daily oral gavage. The results in rats showed that 75 mg/kg CCC treatment induced hepatic steatosis, predominantly microvesicular steatosis with a small amount of macrovesicular steatosis, in rat livers and 200 mg/kg CCC treatment induced liver damage including inflammatory infiltration, hepatic sinusoidal dilation and necrosis. In vitro, HepG2 cells were treated with CCC (0, 30, 60, 120, 240 and 480 μg/mL) for 24 h. And the results showed that CCC above 120 μg/mL induced an increase in triglyceride and neutral lipid levels of HepG2 cells. Mechanism exploration revealed that CCC treatment promoted the activation of mTOR/SREBP1 signalling pathway and inhibited activation of AMPK in both in vivo rat livers and in vitro HepG2 cells. Treatment with AMPK activator Acadesine (AICAR) could alleviate the lipid accumulation in HepG2 cells induced by CCC. Collectively, the present results indicate that CCC might induce hepatic steatosis by promoting mTOR/SREBP1 mediated lipogenesis via AMPK inhibition.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Effects of Garlic on Glucose Parameters and Lipid Profile: A Systematic Review and Meta-Analysis on Randomized Controlled Trials

(1) Background: The effect of garlic on glucose and lipid metabolism in humans remains controversial. The aim of this study was to investigate the effects of garlic on blood lipid levels and glucose levels in humans through a systematic review and meta-analysis. (2) Methods: We extensively searched four databases, including PubMed, Web of Science, Embase, and the Cochrane Library, up to February 2024. To assess the collective impact of garlic and its supplements on fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG), an analysis was conducted using a random effects model. Subgroup analyses were performed when I2 < 50%. (3) Result: We found that the garlic intervention was effective in controlling FBG (mean difference = -7.01; 95% CI: -8.53, -5.49, p < 0.001), HbA1c (mean deviation = -0.66; 95% CI: -0.76, -0.55, p < 0.001, I2 = 62.9%), TC (mean difference = -14.17; 95% CI: -19.31, -9.03, p < 0.001), and LDL-C (mean difference = -8.20; 95% CI: -15.58, -0.81, p = 0.03); moreover, it also increased the level of HDL-C in humans (mean difference = 2.06; 95% CI: 1.54, 2.59; p < 0.001). Nonetheless, the intervention involving garlic did not yield a substantial impact on triglyceride (TG) levels. (4) Conclusion: The intervention of garlic is beneficial to control blood glucose and blood lipids in humans.

Resveratrol and (-)-Epigallocatechin-3-gallate Regulate Lipid Metabolism by Activating the AMPK Pathway in Hepatocytes

The purpose of this study was to explore the effects of Res and EGCG on cell growth, cellular antioxidant levels, and cellular lipid metabolism in hepatocytes. In this experiment, leghorn male hepatoma (LMH) cells were used as hepatocytes. The results showed that 6.25-25 μM Res and EGCG had no adverse effects on cell viability and growth. Meanwhile, with the increasing dosage of Res and EGCG, the contents of total cholesterol (TC), total glyceride (TG), and malondialdehyde (MDA) in hepatocytes decreased significantly (p < 0.05), while the contents of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD), and catalase (CAT) increased significantly (p < 0.05). In addition, western blot results showed that Res and EGCG could significantly increase the expression of p-AMPK protein and reduce the expression of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) protein in hepatocytes (p < 0.05). Moreover, q-PCR results showed that with the increase in Res and EGCG, the expression of cholesterol- and fatty acid synthesis-related genes decreased significantly (p < 0.05). In conclusion, Res and EGCG can increase the antioxidant capacity of hepatocytes and reduce the synthesis of TC and TG in hepatocytes by activating AMPK, thereby regulating lipid metabolism in hepatocytes.

Advances in the study of vascular related protective effect of garlic (Allium sativum) extract and compounds

Garlic (Allium sativum) is a functional food containing multiple bioactive compounds that find widespread applications in culinary and medicinal practices. It consists of multiple chemical components, including allicin and alliin. This article offers a comprehensive review of the protective effects of garlic extracts and their active constituents on the vascular system. In vitro and in vivo experiments have shown that garlic extracts and their active ingredients possess various bioactive properties. These substances demonstrate beneficial effects on blood vessels by demonstrating anti-inflammatory and antioxidant activities, inhibiting lipid accumulation and migration, preventing lipid peroxidation, promoting angiogenesis, reducing platelet aggregation, enhancing endothelial function, and inhibiting endothelial cell apoptosis. In clinical studies, garlic and its extracts have demonstrated their efficacy in managing vascular system diseases, including atherosclerosis, diabetes, and high cholesterol levels. In summary, these studies highlight the potential therapeutic roles and underlying mechanisms of garlic and its constituents in managing conditions like diabetes, atherosclerosis, ischemic diseases, and other vascular disorders.

Effect of garlic on the components of metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

ETHNOPHARMACOLOGICAL RELEVANCE

Metabolic diseases are the major causes of macrovascular and microvascular complications which lead to morbidity and mortality. Traditionally, garlic has been used as food and medicine for more than 5000 years. However, efficacy studies have shown conflicting results regarding the garlic effect.

AIM OF THE STUDY

This study aims to evaluate the efficacy of garlic on the components of metabolic syndrome (MetS) in metabolic disease patients.

MATERIALS AND METHODS

This study was a systematic review and meta-analysis of randomized controlled trials (RCTs). Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), and Google scholar were searched till December 25, 2021 for identifying the relevant studies that have shown the effects of garlic on components of metabolic syndrome in metabolic disease patients. The mean difference with 95% CI was calculated using fixed-effect or random-effect models.

RESULTS

The effect of garlic has shown significant changes on waist circumference (p-value= <0.0001), total cholesterol (p < 0.0001), low density lipoprotein (p = 0.01), high density lipoprotein (p < 0.00001), triglycerides (p < 0.00001), systolic blood pressure (p < 0.00001), diastolic blood pressure (p < 0.00001), glucose (p < 0.00001), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) (p = 0.04), C-reactive protein (p < 0.00001), tumor necrosis factor (TNF)-α (p = 0.002), interleukin (IL)-6 (p = 0.0001). Subgroup analysis has shown the favorable effects of garlic in metabolic disease patients.

CONCLUSION

Our meta-analysis results confirm the findings that garlic could be useful as an anti-hyperlipidemic, anti-hyperglycemic, anti-hypertensive and anti-inflammatory drug.

Natural products in non-alcoholic fatty liver disease (NAFLD): Novel lead discovery for drug development

With changing lifestyles, non-alcoholic fatty liver disease (NAFLD) has become the most prevalent liver disease worldwide. A substantial increase in the incidence, mortality, and associated burden of NAFLD-related advanced liver disease is expected. Currently, the initial diagnosis of NAFLD is still based on ultrasound and there is no approved treatment method. Lipid-lowering drugs, vitamin supplementation, and lifestyle improvement treatments are commonly used in clinical practice. However, most lipid-lowering drugs can produce poor patient compliance and specific adverse effects. Therefore, the exploration of bio-diagnostic markers and active lead compounds for the development of innovative drugs is urgently needed. More and more studies have reported the anti-NAFLD effects and mechanisms of natural products (NPs), which have become an important source for new drug development to treat NAFLD due to their high activity and low side effects. At present, berberine and silymarin have been approved by the US FDA to enter clinical phase IV studies, demonstrating the potential of NPs against NAFLD. Studies have found that the regulation of lipid metabolism, insulin resistance, oxidative stress, and inflammation-related pathways may play important roles in the process. With the continuous updating of technical means and scientific theories, in-depth research on the targets and mechanisms of NPs against NAFLD can provide new possibilities to find bio-diagnostic markers and innovative drugs. As we know, FXR agonists, PPARα agonists, and dual CCR2/5 inhibitors are gradually coming on stage for the treatment of NAFLD. Whether NPs can exert anti-NAFLD effects by regulating these targets or some unknown targets remains to be further studied. Therefore, the study reviewed the potential anti-NAFLD NPs and their targets. Some works on the discovery of new targets and the docking of active lead compounds were also discussed. It is hoped that this review can provide some reference values for the development of non-invasive diagnostic markers and new drugs against NAFLD in the clinic.

Allium sativum: A potential natural compound for NAFLD prevention and treatment

Introduction

Non-alcoholic fatty liver disease (NAFLD) results from an excessive accumulation of fat particles that causes liver inflammation, which ultimately causes liver damage. There is still considerable uncertainty about the effects of any nutritional supplements compared to no additional intervention. This review aimed to evaluate the efficacy of Allium sativum (A. sativum), known as garlic, in preventing and treating NAFLD.

Methods

A systematic search based on a search strategy consisting of two components of "NAFLD" and "Allium sativum" in databases including PubMed, Web of Science (WoS), and SCOPUS was conducted on papers evaluating the effects of A. sativum on NAFLD treatment and prevention. We obtained studies from inception until 20 September 2022, followed by study selection and data extraction based on our eligibility criteria. Consequently, qualitative and quantitative synthesis was conducted.

Results

Our qualitative analysis reveals that A. sativum consumption is linked to the prevention of NAFLD, especially in males, although qualitative data in this study regarding the therapeutic properties of NAFLD was controversial. Our meta-analysis showed that NAFLD patients treated with A. sativum have significantly declined aminotransferase levels. That is to say, our meta-analysis revealed a lower alanine transaminase (ALT) (SMD = -0.580, 95%CI = -0.822 to -0.338), and aspartate transaminase (AST(SMD = -0.526, 95%CI = -0.767 to -0.284) in NAFLD patients treated with A. sativum compared to the placebo group. Also, pooling data from case-control studies showed that A. sativum consumption decreases the odds of being diagnosed with NAFLD by 46% (OR = 0.538, 95%CI = 0.451-0.625).

Conclusion

A. sativum consumption is not merely associated with NAFLD prevention but also results in a considerable decline in blood aminotransferase levels in patients diagnosed with NAFLD. To put it simply, A. sativum is linked to a decline in AST and ALT, which are considered reliable biomarkers of NAFLD response to treatment. Nevertheless, A. sativum is insufficient to improve NAFLD independent of other dietary amendments and lifestyle modifications.

Natural Foods for the Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. The etiology of NAFLD is highly heterogeneous, which occurs and develops under the joint action of metabolism, inflammation, genetics, environment, and gut microbiota. At present, the principal therapeutic modalities targeting NAFLD are lifestyle interventions such as weight loss through diet and exercise. At present, there is no established therapy for the treatment of NAFLD, and many therapies are associated with a variety of side effects. A great number of in vitro and in vivo experiments have indicated that there are many natural foods that have therapeutic potential for NAFLD. This review summarizes the natural foods and their mechanisms that were found in recent years, furthermore, provides further information relevant to the treatment of NAFLD.

Roles and mechanisms of garlic and its extracts on atherosclerosis: A review

The prevention and treatment of cardiovascular diseases (CVDs) have achieved initial results, but the number of CVDs patients will increase rapidly in the next 10 years. Atherosclerosis (AS) is a significant risk factor for CVDs. The impact of lifestyle and daily diet varies considerably between different countries and continents and has been shown to affect the development of various diseases such as diabetes and CVDs. Primary and secondary prevention using alternative supplements and methods to avoid or reduce the use of traditional pharmacological drugs have also become popular. One of the reasons for this is that pharmacological drugs with lipid-lowering, and blood pressure-lowering effects cause many side effects that may negatively impact the quality of life. Patients are now emphasizing reliance on lifestyle changes to reduce cardiovascular risks. Garlic is a medicinal and edible plant that has been used for a long time. In order to reveal garlic application in the prevention and treatment of AS, reviewing the latest domestic and international studies through searching databases. The result shows that the antiatherogenic role of garlic is eximious. And the mechanisms are mainly related to hypolipidemic, antioxidant, antithrombotic, inhibiting angiogenesis, protecting endothelial cells, anti-inflammatory, anti-apoptotic, inhibiting vascular smooth muscle proliferation, and regulating gut microbiota. The main signaling pathways involve AMPK/TLRs, Keap1/Nrf2, PI3K/AKT, PPARγ/LXRα, GEF-H1/RhoA/Rac, etc. The antiatherogenic actions and molecular mechanism of garlic were reviewed in this study to obtain a robust evidence basis for the clinical application and mechanistic study and provide a theoretical basis for further utilization of garlic.

Natural Garlic Organosulfur Compounds Prevent Metabolic Disorder of Lipid and Glucose by Increasing Gut Commensal Bacteroides acidifaciens

A number of reports of the effects of garlic on gut microbiota revealed that the active garlic organosulfur compounds (OSCs) are destabilized by the action of alliinase during garlic preparation. In this study, garlic alliinase was deactivated to obtain stable garlic OSCs. Experiments with C57BL/6J mice fed with lipid and glucose metabolic disorder-inducing Western diet (WD) revealed that stable garlic OSCs prevented the disorder by increasing the relative abundance of gut Bacteroides acidifaciens. Molecular analysis indicated that garlic OSCs inhibited dyslipidemia and fatty liver by increasing taurine and subsequently promoting hepatic fatty acid β-oxidation. In parallel, garlic OSCs could meliorate glucose homeostasis by inhibiting dipeptidyl peptidase-4 (DPP-4) and hepatic gluconeogenesis. In vitro bacterial culture experiments revealed that garlic OSCs directly increased the growth of gut Bacteroides acidifaciens. The results of this study demonstrate that the molecular mechanism of the preventive effect of garlic OSCs on the WD-induced metabolic disorder is attributed to the enhanced growth of Bacteroides acidifaciens and the consequent increase in taurine.

Garlic: A systematic review of the effects on cardiovascular diseases

Allium sativum (garlic) certainly is one of the oldest horticultural crops in the world and presents bioactive compounds that are related to the garlic's effects on human health. Several authors have shown beneficial effects on diabetes, hypertension, dyslipidemia, obesity, and cardiovascular diseases (CVD), which are among the most relevant causes of mortality in the world. The aim of this systematic review was to evaluate the effects of garlic in the risk factors of CVD and evaluate its economic importance. MEDLINE-PubMed, COCHRANE, EMBASE, and Google Scholar databases were searched. The included studies showed that the use of garlic can reduce blood pressure, waist circumference, body mass index, LDL-c, non-HDL-c, total cholesterol, triglycerides, and inflammatory markers. It also can increase the levels of HDL-c and can improve cardiovascular parameters such as coronary artery calcium, microcirculation, epicardial and periaortic adipose tissue, post occlusive reactive hyperemia, low attenuation plaque, carotid intima-media thickness; and carotid intima-media thickness. Due to these reasons, garlic can be considered in the prevention and treatment of CVD risk factors.

Effects of garlic powder supplementation on metabolic syndrome components, insulin resistance, fatty liver index, and appetite in subjects with metabolic syndrome: A randomized clinical trial

The prevalence of metabolic syndrome (MetS) is increasing. It is closely linked to nonalcoholic fatty liver disease. Garlic consumption as a strategy for the management of MetS has been suggested. We investigated the effect of garlic supplementation on MetS components, insulin resistance, fatty liver index (FLI), and appetite in subjects with MetS. Ninety subjects were assigned to receive 1,600 mg/d garlic powder or placebo for 3 months. The primary outcomes included MetS components. The secondary outcomes included insulin resistance, FLI, and appetite. Garlic supplementation compared with the placebo led to a significant increase in high density lipoprotein-cholesterol (4.5 vs. -1.8, p < .001) and a significant reduction in waist circumference (-1.3 vs. 0.0, p = .001), diastolic blood pressure (-6.7 vs. 0.0, p < .001), systolic blood pressure (-7.7 vs. 0.5, p < .001), triglyceride (-40.0 vs. 0.1, p < .001), γ-glutamyl transferase (-3.2 vs. 0.6, p = .01), FLI (-5.5 vs. 0.1, p < .001), insulin (-2.9 vs. -1.1, p < .001), homeostatic model of assessment for insulin resistance (-0.5 vs. -0.3, p < .001) and appetite (hunger: -11.7 vs. 1.7, p < .001; fullness: 10.0 vs. 0.3, p = .001; desire to eat: -6.7 vs. 2.1, p < .001; and ability to eat: -11.5 vs. -1.0, p < .001). Garlic improves MetS components, insulin resistance, FLI, and appetite.

Beneficial Effects of Plant-Derived Natural Products on Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease is becoming in one of the most prevalent liver diseases that leads to liver transplantation. This health problem is a multisystem disease with a complex pathogenesis that involves liver, adipose tissue, gut, and muscle. Although several pharmacological agents have been investigated to prevent or treat non-alcoholic fatty liver disease, currently there is no effective treatment for the management of this chronic liver disease. Nonetheless, the use of natural products has emerged as a alternative therapeutic for the treatment of hepatic diseases, including non-alcoholic fatty liver disease, due to its anti-inflammatory, antioxidant, antidiabetic, insulin-sensitizing, antiobesity, hypolipidemic, and hepatoprotective properties. In the present review, we have discussed the evidence from experimental and clinical studies regarding the potential beneficial effects of plant-derived natural products (quercetin, resveratrol, berberine, pomegranate, curcumin, cinnamon, green tea, coffee, garlic, ginger, ginseng, and gingko biloba) for the treatment or prevention of non-alcoholic fatty liver disease.

Ursolic acid alleviates lipid accumulation by activating the AMPK signaling pathway in vivo and in vitro

The mechanism underlying the effect of ursolic acid (UA) on lipid metabolism remains unclear. This study aimed to explore the mechanisms of UA in reducing lipid accumulation in free fatty acids-cultured HepG2 cells and in high-fat-diet-fed C57BL/6J mice. In vivo, UA effectively alleviated liver steatosis and decreased the size of adipocytes in the epididymis. It also significantly decreased the total cholesterol (TC) and triglyceride (TG) contents in the liver and plasma in C57BL/6 mice. In vitro, UA (20 µM) significantly reduced lipid accumulation; the intracellular TC contents decreased from 0.078 ± 0.0047 to 0.049 ± 0.0064 µmol/mg protein, and TG contents from 0.133 ± 0.005 to 0.066 ± 0.0047 µmol/mg protein, in HepG2 cells. Furthermore, UA reduced the mRNA expression related to fat synthesis, enhanced the mRNA expression related to adipose decomposition, and dramatically upregulated the protein expression of P-AMPK in vivo and in vitro. Of note, these protective effects of UA on a high-fat environment were blocked by the AMPK inhibitor (compound C) in vitro. In addition, the molecular docking results suggested that UA could be docked to the AMPK protein as an AMPK activator. These results indicated that UA lowered the lipid content probably via activating the AMPK signaling pathway, thereby inhibiting lipid synthesis and promoting fat decomposition. PRACTICAL APPLICATION: Ursolic acid (UA) widely exists in vegetables and fruits. This study highlighted a lipid-lowing mechanism of UA in HepG2 cells and C57BL/6J mice. The data indicated that UA might be used in lipid-lowering functional foods.

The Pivotal Role of the Dysregulation of Cholesterol Homeostasis in Cancer: Implications for Therapeutic Targets

Cholesterol plays an important role in cellular homeostasis by maintaining the rigidity of cell membranes, providing a medium for signaling transduction, and being converted into other vital macromolecules, such as sterol hormones and bile acids. Epidemiological studies have shown the correlation between cholesterol content and cancer incidence worldwide. Accumulating evidence has shown the emerging roles of the dysregulation of cholesterol metabolism in cancer development. More specifically, recent reports have shown the distinct role of cholesterol in the suppression of immune cells, regulation of cell survival, and modulation of cancer stem cells in cancer. Here, we provide a comprehensive review of the epidemiological analysis, functional roles, and mechanistic action of cholesterol homeostasis in regard to its contribution to cancer development. Based on the existing data, cholesterol homeostasis is identified to be a new key player in cancer pathogenesis. Lastly, we also discuss the therapeutic implications of natural compounds and cholesterol-lowering drugs in cancer prevention and treatment. In conclusion, intervention in cholesterol metabolism may offer a new therapeutic avenue for cancer treatment.

Effects of different fatty acids on BRL3A rat liver cell damage

To evaluate the effects of fatty acids on endoplasmic reticulum (ER) stress, oxidative stress, and lipid damage. We treated BRL3A rat liver cells with, linoleic (LA), linolenic, oleic (OA), palmitic (PA), palmitoleic (POA), or stearic (SA) acid for 12 hr. The characteristics of cell lipid deposition, oxidative stress indexes, ER stress markers, nuclear factor κB p65 (NF-κB p65), lipid synthesis and transport regulators, and cholesterol metabolism regulators were analyzed. Endoplasmic chaperones like glucose-regulated protein 78, CCAAT-enhancer-binding protein, NF-κB p65, hydrogen peroxide, and malonaldehyde in PA- and SA-treated cells were significantly higher than in other treated cells. Deposition of fatty acids especially LA and POA were significantly increased than in other treated cells. De novo lipogenesis regulators sterol regulatory element-binding protein 1c, fatty acid synthase, and acetyl-coenzyme A carboxylase 1 (ACC1) expression were significantly increased in all fatty acid stimulation groups, and PA- and SA-treated cells showed lower p-ACC1 expression and higher scd1 expression than other fatty acid groups. Very low-density lipoprotein synthesis and apolipoprotein B100 expression in free fatty acids treated cells were significantly lower than control. PA, SA, OA, and POA had shown significantly increased cholesterol synthesis than other treated cells. PA and SA showed the lower synthesis of cytochrome P7A1 and total bile acids than other fatty acids treated cells. Excess of saturated fatty acids led to severe ER and oxidative stress. Excess unsaturated fatty acids led to increased lipid deposition in cultured hepatocytes. A balanced fatty acid intake is needed to maintain lipid homeostasis.

Mechanisms underlying the attenuation of chronic inflammatory diseases by aged garlic extract: Involvement of the activation of AMP-activated protein kinase

AMP-activated protein kinase (AMPK) is an ubiquitously expressed serine/threonine kinase and an important regulator of energy metabolism. The decreased activity of AMPK induced by low-grade chronic inflammation has been implicated in several diseases, including type 2 diabetes and atherosclerosis. However, the activation of AMPK by natural and synthetic products can ameliorate these diseases through the inhibition of inflammation. For example, aged garlic extract (AGE) has been shown to enhance the phosphorylation of Thr172 of the α-subunit of AMPK in several tissues of disease model animals. In addition, AGE has been reported to suppress the progression of atherosclerotic plaque formation in an animal model of atherosclerosis. Moreover, AGE has been found to decrease the level of plasma glycated albumin and to improve hyperglycemia in an animal model of type 2 diabetes. These inhibitory effects of AGE are induced by the suppression of the inflammatory response. In the present review, we discuss the mechanisms through which AGE activates AMPK, as well as the mechanisms through which the activation of AMPK by AGE modulates the inflammatory response in disease models.

Insulin signaling in LepR cells modulates fat and glucose homeostasis independent of leptin

Hypothalamic neurons detect changes in circulating hormones such as leptin and insulin and put forward outputs to sustain energy and glucose homeostasis. Because leptin and insulin receptors colocalize in ~40-60% of neurons in the hypothalamus, we characterized the metabolic phenotype of mice with selective deletion of the insulin receptor (InsR) in LepR cells. LR^ΔInsR mice presented no difference in body weight and insulin levels but increased fat mass. In the light phase, LR^ΔInsR mice exhibited increased food intake, locomotor activity, carbon dioxide production, and respiratory exchange rate. These mice showed reduced fat oxidation and reduced expression of cluster of differentiation 36 and AMP-activated protein kinase-α₁ in the liver, increased glucose oxidation in the light phase, and overall reduced basal glucose levels. To verify the impact of InsR deletion in LepR cells in obesity, we generated ob/ ob InsR^fl, ob/ ob LR^cre, and ob/ ob LR^ΔInsR mice. The ob/ ob LR^ΔInsR mice had higher body weight, fat mass, and expression of genes related to fat metabolism in the liver. No difference in food intake despite increased neuropeptide Y and agouti-related peptide expression, and no difference in energy expenditure, fat, or glucose oxidation was found in ob/ ob LR^ΔInsR compared with LR^cre or LR^ΔInsR controls. Remarkably, basal glucose levels were reduced, and the expression of genes associated with glucose metabolism in the liver was higher. Insulin signaling in LepR cells is required for the proper fat and glucose oxidation. These effects are independent of leptin given that the leptin-deficient ob/ ob LR^ΔInsR mice also presented reduced glycemia and higher adiposity. The mechanisms underlying these responses remain to be unveiled.

MiR-451a attenuates free fatty acids-mediated hepatocyte steatosis by targeting the thyroid hormone responsive spot 14 gene

The thyroid hormone responsive spot 14 (THRSP) gene is a de novo lipogenesis-related gene that plays a significant role in the initiation and development of nonalcoholic fatty liver disease (NAFLD). Several previous studies had shown that endogenous and environmental factors could regulate the expression of THRSP. The role of microRNAs (miRNAs), however, in controlling THRSP expression has not been investigated. In this study, we first constructed the hepatic steatosis cell model by using a mixture of free fatty acids (FFAs; oleate/palmitate, 2:1 ratio) to treat and demonstrate the promotive role of THRSP in lipid accumulation in hepatic cells. By analyzing the photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) database and performing a luciferase reporter assay, we confirmed that microRNA-451a specifically binds to mouse and human THRSP 3'UTR and inhibits its activity. Overexpression of miR-451a efficiently reduced THRSP mRNA and protein expression as well as triglyceride (TG) accumulation in cultured hepatic cells (AML12 and HepG2). Moreover, overexpression of miR-451a significantly decreases TG accumulation in the livers of mice injected with an miR-451a agomir. All these results demonstrated that miR-451a might participate in the FFA-induced hepatic steatosis by regulating the expression of the THRSP gene which represents a new potential target for NAFLD therapy.

Potential Therapeutic Benefits of Herbs and Supplements in Patients with NAFLD

Our aim is to review the efficacy of various herbs and supplements as a possible therapeutic option in the treatment and/or prevention of nonalcoholic fatty liver disease (NAFLD). We performed a systematic review of medical literature using the PubMed Database by searching the chemical names of many common herbs and supplements with “AND (NAFLD or NASH)”. Studies and medical literature that discussed the roles and usage of herbs and supplements in NAFLD and nonalcoholic steatohepatitis (NASH) from inception until 20 June 2018 were reviewed. Many studies have claimed that the use of various herbs and supplements may improve disease endpoints and outcomes related to NAFLD and/or NASH. Improvement in liver function tests were noted. Amelioration or reduction of lobular inflammation, hepatic steatosis, and fibrosis were also noted. However, well-designed studies demonstrating improved clinical outcomes are lacking. Furthermore, experts remain concerned about the lack of regulation of herbs/supplements and the need for further research on potential adverse effects and herb–drug interactions. In conclusion, preliminary data on several herbs have demonstrated promising antioxidant, anti-inflammatory, anti-apoptotic, and anti-adipogenic properties that may help curtail the progression of NAFLD/NASH. Clinical trials testing the safety and efficacy must be completed before widespread use can be recommended.

Roles of Spicy Foods and Their Bioactive Compounds in Management of Hypercholesterolemia

Hypercholesterolemia, as one of the major risk factors in development of cardiovascular diseases, is of mounting prevalence worldwide in recent years. Many nutraceuticals and phytochemical supplements serve as a promising complementary therapy in the management of hypercholesterolemia. Among them, spicy foods have attracted special attention. Plasma lipid-lowering activity of garlic, ginger, and turmeric have been well-studied in both humans and animals. Consumption of either 3 g/day of ginger or 2 g/day of curcumin for over 4 weeks effectively reduced blood cholesterol in hypercholesterolemia subjects. However, effects of chili and black peppers on blood cholesterol are studied little clinically. The present review is to summarize the findings of recent studies on the efficacy and mechanism of spicy foods and their primary bioactive components in management of hypercholesterolemia from preclinical studies to clinical trials.

Aged garlic extract suppresses inflammation in apolipoprotein E-knockout mice

SCOPE

Chronic inflammation plays a major role in the formation and progression of atherosclerotic plaques. To clarify the mode of action of aged garlic extract (AGE) to retard atherosclerosis, we investigated whether AGE suppresses the inflammation in apolipoprotein E-knockout (ApoE-KO) mice.

METHODS AND RESULTS

ApoE-KO mice were fed standard diet with or without 3% AGE for 12 wk. AGE feeding inhibited the progression of atherosclerotic lesion by 27% and reduced the level of C-reactive protein (CRP) and thromboxane B₂ (TXB₂ ), a marker of platelet activation, in serum by 39 and 33%, respectively, compared to ApoE-KO mice without AGE treatment. AGE treatment also decreased the level of tumor necrosis factor alpha (TNF-α), a major stimulus inducing CRP production, in the liver by 35%. AGE decreased the level of interleukin-1 receptor-associated kinase 4 (IRAK4) by 60% and almost doubled the level of phospho-AMP-activated protein kinase (p-AMPK) in the liver.

CONCLUSION

The anti-atherosclerotic effect of AGE involves the suppression of inflammation by reducing the serum level of CRP and TXB₂ , and the protein level of TNF-α and IRAK4, and increasing AMPK activity in liver.

Osthole attenuates lipid accumulation, regulates the expression of inflammatory mediators, and increases antioxidants in FL83B cells

Osthole is found in Cnidium monnieri (L.) and has anti-inflammatory and anti-oxidative properties. It also inhibits the proliferation of hepatocellular carcinoma cells. This study aimed to evaluate the osthole suppressive nonalcoholic fatty liver disease effects in oleic acid (OA)-induced hepatic steatosis and if it can modulate inflammatory responses and oxidative stress. FL83B cells were pretreated with OA (250μΜ) for 24h, and then added different concentrations of osthole (3-100μM) for 24h. Subsequently, lipolysis and transcription factors of adipogenesis and phosphorylation of AMP-activated protein kinase proteins were measured. In addition, cells with OA-induced steatosis were H₂O₂-stimulated, and then incubated with osthole to evaluated if it could suppress its progression to steatohepatitis. Osthole significantly enhanced glycerol release and lipolysis protein expression. Osthole also promoted phosphorylation of AMP-activated protein kinases and increased the activity of triglyceride lipase and hormone- sensitive lipase. Osthole suppressed the nuclear transcription factor kappa-B and the p38 mitogen-activated protein kinase pathway, and decreased the malondialdehyde concentration in FL83B cells with OA-induced steatosis that were treated with H₂O₂. These results suggest that osthole might suppress nonalcoholic fatty liver disease by decreasing lipid accumulation, and through its anti-oxidative and anti-inflammatory effects via blocked NF-κB and MAPK signaling pathways.

Functional foods and dietary supplements for the management of dyslipidaemia

Dyslipidaemia is characterized by increased blood levels of total or LDL cholesterol and triglycerides, or decreased HDL cholesterol levels, and is a risk factor for cardiovascular disease. Dyslipidaemia has a high worldwide prevalence, and many patients are turning to alternatives to pharmacotherapy to manage their lipid levels. Lifestyle modification should be emphasized in all patients to reduce cardiovascular risk and can be initiated before pharmacotherapy in primary prevention of cardiovascular disease. Many functional foods and natural health products have been investigated for potential lipid-lowering properties. Those with good evidence for a biochemical effect on plasma lipid levels include soy protein, green tea, plant sterols, probiotic yogurt, marine-derived omega-3 fatty acids and red yeast rice. Other products such as seaweed, berberine, hawthorn and garlic might confer some limited benefit in certain patient groups. Although none of these products can reduce lipid levels to the same extent as statins, most are safe to use in addition to other lifestyle modifications and pharmacotherapy. Natural health products marketed at individuals with dyslipidaemia, such as policosanol, guggulsterone and resveratrol, have minimal definitive evidence of a biochemical benefit. Additional research is required in this field, which should include large, high-quality randomized controlled trials with long follow-up periods to investigate associations with cardiovascular end points.

Inhibitory effect of esculetin on free-fatty-acid-induced lipid accumulation in human HepG2 cells through activation of AMP-activated protein kinase

This study aimed to determine the lipid-lowering effect of esculetin (6,7-dihydroxycoumarin), a coumarin derivative, using a cell model of steatosis induced by a mixture of free fatty acids (FFAs). Esculetin dose-dependently inhibited intracellular lipid accumulation by down-regulating the protein expression of lipogenic genes such as sterol regulatory element-binding protein-1c (SREBP1c) and fatty acid synthase (FAS) in FFAs-induced HepG2 cells. Moreover, esculetin significantly elevated the activation of the adenosine monophosphate-activated protein kinase (AMPK) signaling pathways in HepG2 hepatocytes. The anti-lipogenic effects of esculetin mediated by AMPK activation were abolished when FFAs-induced HepG2 cells were treated with a specific inhibitor of AMPK, i.e., compound C. These results suggest that esculetin attenuates hepatic lipid accumulation by inhibiting lipogenesis through the modulation of AMPK signaling pathway on FFAs-induced steatosis in HepG2 cells and may be used for the prevention of nonalcoholic fatty liver disease (NAFLD).

Aged garlic extract suppresses the increase of plasma glycated albumin level and enhances the AMP-activated protein kinase in adipose tissue in TSOD mice

SCOPE

In this study, we investigated the effect of aged garlic extract (AGE) on the high level of blood glucose in Tsumura Suzuki Obese-Diabetes (TSOD) mice.

METHODS AND RESULTS

TSOD mice were fed standard diet with or without 2% AGE for 19 weeks. AGE treatment lowered the blood glucose level and significantly reduced the plasma level of glycated albumin in TSOD mice as compared with those without AGE treatment. In addition, AGE treatment increased the level of phosphorylated AMP-activated protein kinase (AMPK) in the adipose tissue, liver and muscle that played an important role in the maintenance of insulin sensitivity. Moreover, AGE treatment also suppressed the mRNA expression of fatty acid synthase, a known factor regulated by AMPK, and monocyte chemoattractant protein 1, one of the representative inflammatory chemokines, in the adipose tissue but not in the liver.

CONCLUSION

AGE treatment suppresses the increase of plasma glycated albumin level in TSOD mice and this effect is accompanied by the activation of AMPK in adipose tissue, and suggests that AGE may play a potential role in the prevention and treatment of type 2 diabetes.

The effect of oleuropein from olive leaf (Olea europaea) extract on Ca²⁺ homeostasis, cytotoxicity, cell cycle distribution and ROS signaling in HepG2 human hepatoma cells

Oleuropein, a phenolic compound found in the olive leaf (Olea europaea), has been shown to have biological activities in different models. However, the effects of oleuropein on Ca(2+) homeostasis, cytotoxicity, cell cycle distribution and ROS signaling in liver cells have not been analyzed. Oleuropein induced [Ca(2+)]i rises only in HepG2 cells but not in AML12, HA22T or HA59T cells due to the different status of 3-hydroxy-3-methylglutaryl-CoA reductase expression. In HepG2 cells, this Ca(2+) signaling response was reduced by removing extracellular Ca(2+), and was inhibited by the store-operated Ca(2+) channel blockers 2-APB and SKF96365. In Ca(2+)-free medium, pretreatment with the ER Ca(2+) pump inhibitor thapsigargin abolished oleuropein-induced [Ca(2+)]i rises. Oleuropein induced cell cycle arrest which was associated with the regulation of p53, p21, CDK1 and cyclin B1 levels. Furthermore, oleuropein elevated intracellular ROS levels but reduced GSH levels. Treatment with the intracellular Ca(2+) chelator BAPTA-AM or the antioxidant NAC partially reversed oleuropein-induced cytotoxicity. Together, in HepG2 cells, oleuropein induced [Ca(2+)]i rises by releasing Ca(2+) from the ER and causing Ca(2+) influx through store-operated Ca(2+) channels. Moreover, oleuropein induced Ca(2+)-associated cytotoxicity that involved ROS signaling and cell cycle arrest. This compound may offer a potential therapy for treatment of human hepatoma.

A review on possible therapeutic targets to contain obesity: The role of phytochemicals

The prevalence and severity of obesity has increased markedly in recent decades making it a global public health concern. Since obesity is a potential risk factor in the development of hypertension, type-2 diabetes, cardiovascular diseases, infertility, etc., it is no more viewed as a cosmetic issue. Currently, only a few FDA-approved anti-obesity drugs like Orlistat, Lorcaserin and Phentermine-topiramate are available in the market, but they have considerable side effects. On the other hand, bariatric surgery as an alternative is associated with high risk and expensive. In view of these there is a growing trend towards natural product-based drug intervention as one of the crucial strategies for management of obesity and related ailments. In Asian traditional medicine and Ayurvedic literature a good number of plant species have been used and quoted for possible lipid-lowering and anti-obesity effects; however, many of them have not been evaluated rigorously for a definite recommendation and also lack adequate scientific validation. This review explores and updates on various plant species, their used parts, bioactive components and focuses multiple targets/pathways to contain obesity which may pave the way to develop novel and effective drugs. We also summarised different drugs in use to treat obesity and their current status. Nature is future promise of our wellbeing.

Hugan Qingzhi Exerts Anti-Inflammatory Effects in a Rat Model of Nonalcoholic Fatty Liver Disease

Ethnopharmacological Relevance. The Hugan Qingzhi tablet (HQT) is a traditional Chinese medicine used for treating NAFLD (nonalcoholic fatty liver disease). The present study evaluated the anti-inflammatory effects of HQT in rats with NAFLD. Materials and Methods. HQT was administered daily to the NAFLD experimental groups. Biochemical markers, histopathological data, and oxidative stress/antioxidant biomarkers were determined. Proinflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6) were detected by enzyme-linked immunoassay. Expressions of silent information regulator 1 (SIRT1) and acetylated-nuclear-factor kappaB-p65 (Ac-NF-κB-p65) were performed by western blotting. Results. At high and moderate doses, HQT was highly effective in decreasing serum alanine aminotransferase (P < 0.01), aspartate aminotransferase (P < 0.01), hepatic total cholesterol (P < 0.01), triglycerides (P < 0.01), and free fatty acid levels (P < 0.01). Moreover, high and moderate doses of HQT reduced hepatic levels of the proinflammatory cytokines TNF-α (P < 0.01), IL-1β (P < 0.01), and IL-6 (P < 0.01), enhanced SIRT1 expression, and depressed Ac-NF-κB-p65 expression at protein level. Conclusions. In our NAFLD rat model, HQT exerted substantial anti-inflammatory and antioxidant activities, possibly involving the regulation of SIRT1 and Ac-NF-κB-p65 expression.

Cinnamon extract enhances glucose uptake in 3T3-L1 adipocytes and C2C12 myocytes by inducing LKB1-AMP-activated protein kinase signaling

We previously demonstrated that cinnamon extract (CE) ameliorates type 1 diabetes induced by streptozotocin in rats through the up-regulation of glucose transporter 4 (GLUT4) translocation in both muscle and adipose tissues. This present study was aimed at clarifying the detailed mechanism(s) with which CE increases the glucose uptake in vivo and in cell culture systems using 3T3-L1 adipocytes and C2C12 myotubes in vitro. Specific inhibitors of key enzymes in insulin signaling and AMP-activated protein kinase (AMPK) signaling pathways, as well as small interference RNA, were used to examine the role of these kinases in the CE-induced glucose uptake. The results showed that CE stimulated the phosphorylation of AMPK and acetyl-CoA carboxylase. An AMPK inhibitor and LKB1 siRNA blocked the CE-induced glucose uptake. We also found for the first time that insulin suppressed AMPK activation in the adipocyte. To investigate the effect of CE on type 2 diabetes in vivo, we further performed oral glucose tolerance tests and insulin tolerance tests in type 2 diabetes model rats administered with CE. The CE improved glucose tolerance in oral glucose tolerance tests, but not insulin sensitivity in insulin tolerance test. In summary, these results indicate that CE ameliorates type 2 diabetes by inducing GLUT4 translocation via the AMPK signaling pathway. We also found insulin antagonistically regulates the activation of AMPK.

Synthesis and characterization of biocompatible gymnemic acid–gold nanoparticles: a study on glucose uptake stimulatory effect in 3T3-L1 adipocytes

An enhancedin vitroglucose utilization action of the biosynthesized GA–AuNPs.