α-Mangostin Regulates Hepatic Steatosis and Obesity through SirT1-AMPK and PPARγ Pathways in High-Fat Diet-Induced Obese Mice

Emerging roles of SIRT1 in fatty liver diseases

Fatty liver diseases, which are commonly associated with high-fat/calorie diet, heavy alcohol consumption and/or other metabolic disorder causes, lead to serious medical concerns worldwide in recent years. It has been demonstrated that metabolic homeostasis disruption is most likely to be responsible for this global epidemic. Sirtuins are a group of conserved nicotinamide adenine dinucleotide (NAD⁺) dependent histone and/or protein deacetylases belonging to the silent information regulator 2 (Sir2) family. Among seven mammalian sirtuins, sirtuin 1 (SIRT 1) is the most extensively studied one and is involved in both alcoholic and nonalcoholic fatty liver diseases. SIRT1 plays beneficial roles in regulating hepatic lipid metabolism, controlling hepatic oxidative stress and mediating hepatic inflammation through deacetylating some transcriptional regulators against the progression of fatty liver diseases. Here we summarize the latest advances of the biological roles of SIRT1 in regulating lipid metabolism, oxidative stress and inflammation in the liver, and discuss the potential of SIRT1 as a therapeutic target for treating alcoholic and nonalcoholic fatty liver diseases.

Review of Garcinia mangostana and its Xanthones in Metabolic Syndrome and Related Complications

Metabolic syndrome is coexistence of abdominal obesity, hyperglycemia, hyperlipidemia and hypertension that causes cardiovascular diseases, diabetes and their complications, low quality and short lifespan. Garcinia mangostana and its xanthones such as α-mangostin have been shown desirable effects such as anti-obesity, anti-hyperglycemic, anti-dyslipidemia, anti-diabetic and antiinflammatory effects in experimental studies. Various databases such as PubMed, Scopus and Web of Science with keywords of 'Garcinia mangostana', 'mangosteen', 'α-mangostin', 'metabolic syndrome', 'hypoglycemic', 'antihyperglicemic', 'antidiabetic', 'hypotensive', 'antihypertensive', 'atherosclerosis', 'arteriosclerosis' and 'hyperlipidemia' have been investigated in this search without publication time limitation. This study reviewed all pharmacological effects and molecular pathways of G. mangostana and its xanthones in the management of metabolic syndrome and its complications in in-vitro and in-vivo studies. Based on these studies, mangosteen and its xanthones have good potential to design human studies for controlling and modification of metabolic syndrome and its related disorders such as obesity, disrupted lipid profile, diabetes and its complications. Copyright © 2017 John Wiley & Sons, Ltd.

α-Mangostin ameliorates dextran sulfate sodium-induced colitis through inhibition of NF-κB and MAPK pathways

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) of the colon as a target site. Previous reports regarding the efficacy of α-mangostin (αMG) to inhibit nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) as well as relatively high distribution to the colon suggested the therapeutic potential of this compound in UC model. In dextran sodium sulfate (DSS)-induced colitis mice (DSS mice), the disease activity index scores involving diarrhea, bloody stool, body weight reduction, and myeloperoxidase (MPO) activities of the esophagus and colon increased with the reduced colon length. Also histologic disturbances and changes of NF-κB and MAPK pathways including phosphorylation of IκB kinase, ERK1/2, SAPK/JNK and p38 were observed in the colon of the DSS mice. However, all of these impaired conditions in the DSS mice were restored by αMG treatment, and the intestinal metabolism of αMG decreased, increasing its distribution to the colons in the DSS mice compared with the control mice. All of these results suggest that high distribution of αMG in the colon might attenuate DSS-induced colitis by inhibiting NF-κB and MAPK pathways in the colon.

Pharmacology of mangostins and their derivatives: A comprehensive review

Mangosteen (Garcinia mangostana Linn.) is a well-known tropical tree indigenous to Southeast Asia. Its fruit's pericarp abounds with a class of isoprenylated xanthones which are referred as mangostins. Numerous in vitro and in vivo studies have shown that mangostins and their derivatives possess diverse pharmacological activities, such as antibacterial, antifungal, antimalarial, anticarcinogenic, antiatherogenic activities as well as neuroprotective properties in Alzheimer's disease (AD). This review article provides a comprehensive review of the pharmacological activities of mangostins and their derivatives to reveal their promising utilities in the treatment of certain important diseases, mainly focusing on the discussions of the underlying molecular targets/pathways, modes of action, and relevant structure-activity relationships (SARs). Meanwhile, the pharmacokinetics (PK) profile and recent toxicological studies of mangostins are also described for further druggability exploration in the future.

Development and in vivo evaluation of self-microemulsion as delivery system for α-mangostin

α-Mangostin (MG) is a versatile bioactive compound isolated from mangosteen and possesses significant pharmacokinetic shortages. To augment the potential clinical efficacy, MG-loaded self-microemulsion (MG-SME) was designed and prepared in this study, and its potential as a drug loading system was evaluated based on the pharmacokinetic performance and tissue distribution feature. The formula of MG-SME was optimized by an orthogonal test under the guidance of ternary phase diagram, and the prepared MG-SME was characterized by encapsulation efficiency, size distribution, and morphology. Optimized high performance liquid chromatography method was employed to determine concentrations of MG and characterize the pharmacokinetic and tissue distribution features of MG in rodents. It was found that diluted MG-SME was characterized as spherical particles with a mean diameter of 24.6 nm and an encapsulation efficiency of 87.26%. The delivery system enhanced the area under the curve of MG by 4.75 times and increased the distribution in lymphatic organs. These findings suggested that SME as a nano-sized delivery system efficiently promoted the digestive tract absorption of MG and modified its distribution in tissues. The targeting feature and high oral bioavailability of MG-SME promised a good clinical efficacy, especially for immune diseases.

Irbesartan ameliorates hyperlipidemia and liver steatosis in type 2 diabetic db/db mice via stimulating PPAR-γ, AMPK/Akt/mTOR signaling and autophagy

Irbesartan (Irb), a unique subset of angiotensin II receptor blockers (ARBs) with PPAR-γ activation function, has been reported to play a role in renal dysfunction, glucose metabolism, and abnormal lipid profile in diabetic animal models and humans. However, the underlying mechanisms that improve hyperlipidemia and liver steatosis are unclear. This study investigated the effects of Irb on lipid metabolism and hepatic steatosis using the spontaneous type 2 diabetic db/db mouse model. The results demonstrated body and liver weight, food consumption, lipid content in serum and liver tissue, and liver dysfunction as well as hepatic steatosis were increased in db/db mice compared with db/m mice, whereas the increases were reversed by Irb treatment. Moreover, Irb administration resulted in an increase in LC3BII as well as the LC3BII/I ratio through activating PPAR-γ and p-AMPK and inhibiting p-Akt and p-mTOR, thereby inducing autophagy in the db/db mouse liver. Therefore, our findings suggest that Irb can ameliorate hyperlipidemia and liver steatosis by upregulating the expression of PPAR-γ, activating the AMPK/Akt/mTOR signaling pathway and inducing liver autophagy.

Alpha-mangostin from mangosteen (Garcinia mangostana Linn.) pericarp extract reduces high fat-diet induced hepatic steatosis in rats by regulating mitochondria function and apoptosis

Background

Non-alcoholic fatty liver disease (NAFLD) is caused by multiple factors including hepatic oxidative stress, lipotoxicity, and mitochondrial dysfunction. Obesity is among the risk factors for NAFLD alongside type 2 diabetes mellitus and hyperlipidemia. α- mangostin (α-MG) extracts from the pericarps of mangosteen (Garcinia mangostana Linn.) may regulate high fat diet-induced hepatic steatosis; however the underlying mechanisms remain unknown. The aim of this study was to investigate the regulatory effect of α-MG on high fat diet-induced hepatic steatosis and the underlying mechanisms related to mitochondrial functionality and apoptosis in vivo and in vitro.

Methods

Sprague Dawley (SD) rats were fed on either AIM 93-M control diet, a high-fat diet (HFD), or high-fat diet supplemented with 25 mg/day mangosteen pericarp extract (MGE) for 11 weeks. Thereafter, the following were determined: body weight change, plasma free fatty acids, liver triglyceride content, antioxidant enzymes (superoxide dismutase, SOD; glutathione, GSH; glutathione peroxidase, GPx; glutathione reductase GRd; catalase, CAT) and mitochondrial complex enzyme activities. In the in vitro study, primary liver cells were treated with 1 mM free fatty acid (FFA) (palmitate: oleate acid = 2:0.25) to induce steatosis. Thereafter, the effects of α-MG (10 μM, 20 μM, 30 μM) on total and mitochondria ROS (tROS, mitoROS), mitochondria bioenergetic functions, and mitochondrial pathway of apoptosis were examined in the FFA-treated primary liver cells.

Results

The MGE group showed significantly decreased plasma free fatty acids and hepatic triglycerides (TG) and thiorbarbituric acid reactive substances (TBARS) levels; increased activities of antioxidant enzymes (SOD, GSH, GPx, GRd, CAT); and enhanced NADH-cytochrome c reductase (NCCR) and succinate-cytochrome c reductase (SCCR) activities in the liver tissue compared with HFD group. In the in vitro study, α-MG significantly increased mitochondrial membrane potential, enhanced cellular oxygen consumption rate (OCR), decreased tROS (total ROS) and mitoROS (mitochondrial ROS) levels ; reduced Ca²⁺ and cytochrome c (cyt c) release from mitochondria, and reduced caspases 9 and 3 activities compared with control group.

Conclusion

These findings demonstrate α-MG attenuated hepatic steatosis in high fat-diet fed rats potentially through enhanced cellular antioxidant capacity and improved mitochondrial functions as well as suppressed apoptosis of hepatocytes. The findings of study represent a novel nutritional approach on the use of α-MG in the prevention and management of NAFLD.

Adiponectin Suppresses T Helper 17 Cell Differentiation and Limits Autoimmune CNS Inflammation via the SIRT1/PPARγ/RORγt Pathway

T helper 17 (Th17) cells are vital components of the adaptive immune system involved in the pathogenesis of most autoimmune and inflammatory syndromes, and adiponectin(ADN) is correlated with inflammatory diseases such as multiple sclerosis (MS) and type II diabetes. However, the regulatory effects of adiponectin on pathogenic Th17 cell and Th17-mediated autoimmune central nervous system (CNS) inflammation are not fully understood. In this study, we demonstrated that ADN could inhibit Th1 and Th17 but not Th2 cells differentiation in vitro. In the in vivo study, we demonstrated that ADN deficiency promoted CNS inflammation and demyelination and exacerbated experimental autoimmune encephalomyelitis (EAE), an animal model of human MS. Furthermore, ADN deficiency increased the Th1 and Th17 cell cytokines of both the peripheral immune system and CNS in mice suffering from EAE. It is worth mentioning that ADN deficiency predominantly promoted the antigen-specific Th17 cells response in autoimmune encephalomyelitis. In addition, in vitro and in vivo, ADN upregulated sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor γ (PPARγ) and inhibited retinoid-related orphan receptor-γt (RORγt); the key transcription factor during Th17 cell differentiation. These results systematically uncovered the role and mechanism of adiponectin on pathogenic Th17 cells and suggested that adiponectin could inhibit Th17 cell-mediated autoimmune CNS inflammation.

The combination of blueberry juice and probiotics reduces apoptosis of alcoholic fatty liver of mice by affecting SIRT1 pathway

Purpose

To explore the effects of the combination of blueberry juice and probiotics on the apoptosis of alcoholic fatty liver disease (AFLD).

Methods

Healthy C57BL/6J mice were used in the control group (CG). AFLD mice models were established with Lieber–DeCarli ethanol diet and evenly assigned to six groups with different treatments: MG (model), SI (SIRT1 [sirtuin type 1] small interfering RNA [siRNA]), BJ (blueberry juice), BJSI (blueberry juice and SIRT1 siRNA), BJP (blueberry juice and probiotics), and BJPSI (blueberry juice, probiotics, and SIRT1 siRNA). Hepatic tissue was observed using hematoxylin and eosin (HE) and Oil Red O (ORO) staining. Biochemical indexes of the blood serum were analyzed. The levels of SIRT1, caspase-3, forkhead box protein O1 (FOXO1), FasL (tumor necrosis factor ligand superfamily member 6), BAX, and Bcl-2 were measured by reverse transcription-polymerase chain reaction and Western blotting.

Results

HE and ORO staining showed that the hepatocytes were heavily destroyed with large lipid droplets in MG and SI groups, while the severity was reduced in the CG, BJ, and BJP groups (P<0.05). The levels of superoxide dismutase (SOD), reduced glutathione (GSH), and high-density lipoprotein-cholesterol (HDL-C) were increased in BJ and BJP groups when compared with the model group (P<0.05). In contrast, the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), total triglycerides (TGs), total cholesterol, low-density lipoprotein-cholesterol (LDL-C), and malondialdehyde (MDA) were lower in BJ and BJP groups than in the model group (P<0.05). The level of SIRT1 was increased, while the levels of FOXO1, phosphorylated FOXO1, acetylated FOXO1, FasL, caspase-3, BAX, and Bcl-2 were decreased in CG, BJ, and BJP groups (P<0.05). Meanwhile, SIRT1 silence resulted in increase of the levels of FOXO1, phosphorylated FOXO1, acetylated FOXO1, FasL, caspase-3, BAX, and Bcl-2.

Conclusion

The combination of blueberry juice and probiotics reduces apoptosis in AFLD by suppressing FOXO1, phosphorylated FOXO1, acetylated FOXO1, FasL, caspase-3, BAX, and Bcl-2 via the upregulation of SIRT1.

Different Lipopolysaccharide Branched-Chain Amino Acids Modulate Porcine Intestinal Endogenous β-Defensin Expression through the Sirt1/ERK/90RSK Pathway

Nutritional induction of endogenous antimicrobial peptide expression is considered a promising approach to inhibit the outgrowth and infection of pathogenic microbes in mammals. The present study investigated possible regulation of porcine epithelial β-defensins in response to branched-chain amino acids (BCAA) in vivo and in vitro. BCAA treatment increased relative mRNA expression of jejunal and ileal β-defensins in weaned piglets. In IPEC-J2 cells, isoleucine, leucine, and valine could stimulate β-defensin expression, possibly associated with stimulation of ERK1/2 phosphorylation. Inhibition of Sirt1 and ERK completely blocked the activation of ERK and 90RSK protein by isoleucine, simultaneously decreasing defensin expression. BCAA stimulate expression of porcine intestinal epithelial β-defensins with isoleucine the most, potent possibly through activation of the Sirt1/ERK/90RSK signaling pathway. The β-defensins regulation of lipopolysaccharide was related with an ERK-independent pathway. BCAA modulation of endogenous defensin might be a promising approach to enhance disease resistance and intestinal health in young animals and children.

tert-Butoxide mediated cascade desulfonylation/arylation/hydrolysis of cyclic sulfonyimines using diaryliodonium salts: synthesis of diaryl ether derivatives bearing a 2-aldehyde group

Cascades of cyclic sulfonyimines mediated by ^tBuOK with diaryliodonium salts has been developed, giving the diaryl ethers in good yields.