Guggulsterone inhibits adipocyte differentiation and induces apoptosis in 3T3-L1 cells

A machine learning-integrated stepwise method to discover novel anti-obesity phytochemicals that antagonize the glucocorticoid receptor

As a type of stress hormone, glucocorticoids (GCs) affect numerous physiological pathways by binding to the glucocorticoid receptor (GR) and regulating the transcription of various genes. However, when GCs are dysregulated, the resulting hypercortisolism may contribute to various metabolic disorders, including obesity. Thus, attempts have been made to discover potent GR antagonists that can reverse excess-GC-related metabolic diseases. Phytochemicals are a collection of valuable bioactive compounds that are known for their wide variety of chemotypes. Recently, various computational methods have been developed to obtain active phytochemicals that can modulate desired target proteins. In this study, we developed a workflow comprising two consecutive quantitative structure-activity relationship-based machine learning models to discover novel GR-antagonizing phytochemicals. These two models collectively identified 65 phytochemicals that bind to and antagonize GR. Of these, nine commercially available phytochemicals were validated for GR-antagonist and anti-obesity activities. In particular, we confirmed that demethylzeylasteral, a phytochemical of the Tripterygium wilfordii Radix, exhibits potent anti-obesity activity in vitro through GR antagonism.

Biogenic Phytochemicals Modulating Obesity: From Molecular Mechanism to Preventive and Therapeutic Approaches

The incidence of obesity and over bodyweight is emerging as a major health concern. Obesity is a complex metabolic disease with multiple pathophysiological clinical conditions as comorbidities are associated with obesity such as diabetes, hypertension, cardiovascular disorders, sleep apnea, osteoarthritis, some cancers, and inflammation-based clinical conditions. In obese individuals, adipocyte cells increased the expression of leptin, angiotensin, adipocytokines, plasminogen activators, and C-reactive protein. Currently, options for treatment and lifestyle behaviors interventions are limited, and keeping a healthy lifestyle is challenging. Various types of phytochemicals have been investigated for antiobesity potential. Here, we discuss pathophysiology and signaling pathways in obesity, epigenetic regulations, regulatory mechanism, functional ingredients in natural antiobesity products, and therapeutic application of phytochemicals in obesity.

Obesity I: Overview and molecular and biochemical mechanisms

Obesity is a chronic, relapsing condition characterized by excess body fat. Its prevalence has increased globally since the 1970s, and the number of obese and overweight people is now greater than those underweight. Obesity is a multifactorial condition, and as such, many components contribute to its development and pathogenesis. This is the first of three companion reviews that consider obesity. This review focuses on the genetics, viruses, insulin resistance, inflammation, gut microbiome, and circadian rhythms that promote obesity, along with hormones, growth factors, and organs and tissues that control its development. It shows that the regulation of energy balance (intake vs. expenditure) relies on the interplay of a variety of hormones from adipose tissue, gastrointestinal tract, pancreas, liver, and brain. It details how integrating central neurotransmitters and peripheral metabolic signals (e.g., leptin, insulin, ghrelin, peptide YY_3-36) is essential for controlling energy homeostasis and feeding behavior. It describes the distinct types of adipocytes and how fat cell development is controlled by hormones and growth factors acting via a variety of receptors, including peroxisome proliferator-activated receptor-gamma, retinoid X, insulin, estrogen, androgen, glucocorticoid, thyroid hormone, liver X, constitutive androstane, pregnane X, farnesoid, and aryl hydrocarbon receptors. Finally, it demonstrates that obesity likely has origins in utero. Understanding these biochemical drivers of adiposity and metabolic dysfunction throughout the life cycle lends plausibility and credence to the "obesogen hypothesis" (i.e., the importance of environmental chemicals that disrupt these receptors to promote adiposity or alter metabolism), elucidated more fully in the two companion reviews.

Cistanche promotes the adipogenesis of 3T3-L1 preadipocytes

Cistanche deserticola Ma (cistanche) is a traditional herb with a wide range of therapeutic properties. However, no evidence of cistanche’s effect on adipogenesis has been found. The effect of cistanche that promotes the adipogenesis of 3T3-L1 preadipocytes was proved by using MTT spectrophotometry, Nile Red staining, Oil Red O staining and transcriptome sequencing technology. The mRNA level of key transcription factors for adipogenesis such as PPAR, AP2 and LPL were examined by RT-PCR. The results showed that the intracellular lipid content in cistanche treated cells were notably increased when compared with the non-treated cells. Between the differentiation and cistanche treated groups, the expression of adipogenesis related genes such as grow hormone releasing hormone (Ghrp), BCL2/adenovirus E1B interacting protein 3 (Bnip3) and Gastric inhibitory polypeptide receptor (Gipr) were significantly increased. Our findings also verified that cistanche promoted adipogenesis, which was accompanied by up-regulated level of Bnip3 and PPAR. This study could uncover new signaling pathways involved in adipogenesis regulation.

Potential lipolytic regulators derived from natural products as effective approaches to treat obesity

Epidemic obesity is contributing to increases in the prevalence of obesity-related metabolic diseases and has, therefore, become an important public health problem. Adipose tissue is a vital energy storage organ that regulates whole-body energy metabolism. Triglyceride degradation in adipocytes is called lipolysis. It is closely tied to obesity and the metabolic disorders associated with it. Various natural products such as flavonoids, alkaloids, and terpenoids regulate lipolysis and can promote weight loss or improve obesity-related metabolic conditions. It is important to identify the specific secondary metabolites that are most effective at reducing weight and the health risks associated with obesity and lipolysis regulation. The aims of this review were to identify, categorize, and clarify the modes of action of a wide diversity of plant secondary metabolites that have demonstrated prophylactic and therapeutic efficacy against obesity by regulating lipolysis. The present review explores the regulatory mechanisms of lipolysis and summarizes the effects and modes of action of various natural products on this process. We propose that the discovery and development of natural product-based lipolysis regulators could diminish the risks associated with obesity and certain metabolic conditions.

Adipose and non-adipose perspectives of plant derived natural compounds for mitigation of obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Phyto-preparations and phyto-compounds, by their natural origin, easy availability, cost-effectiveness, and fruitful traditional uses based on accumulated experiences, have been extensively explored to mitigate the global burden of obesity.

AIM OF THIS REVIEW

The review aimed to analyse and critically summarize the prospect of future anti-obesity drug leads from the extant array of phytochemicals for mitigation of obesity, using adipose related targets (adipocyte formation, lipid metabolism, and thermogenesis) and non-adipose targets (hepatic lipid metabolism, appetite, satiety, and pancreatic lipase activity). Phytochemicals as inhibitors of adipocyte differentiation, modulators of lipid metabolism, and thermogenic activators of adipocytes are specifically discussed with their non-adipose anti-obesogenic targets.

MATERIALS AND METHODS

PubMed, Google Scholar, Scopus, and SciFinder were accessed to collect data on traditional medicinal plants, compounds derived from plants, their reported anti-obesity mechanisms, and therapeutic targets. The taxonomically accepted name of each plant in this review has been vetted from "The Plant List" (www.theplantlist.org) or MPNS (http://mpns.kew.org).

RESULTS

Available knowledge of a large number of phytochemicals, across a range of adipose and non-adipose targets, has been critically analysed and delineated by graphical and tabular depictions, towards mitigation of obesity. Neuro-endocrinal modulation in non-adipose targets brought into sharp dual focus, both non-adipose and adipose targets as the future of anti-obesity research. Numerous phytochemicals (Berberine, Xanthohumol, Ursolic acid, Guggulsterone, Tannic acid, etc.) have been found to be effectively reducing weight through lowered adipocyte formation, increased lipolysis, decreased lipogenesis, and enhanced thermogenesis. They have been affirmed as potential anti-obesity drugs of future because of their effectiveness yet having no threat to adipose or systemic insulin sensitivity.

CONCLUSION

Due to high molecular diversity and a greater ratio of benefit to risk, plant derived compounds hold high therapeutic potential to tackle obesity and associated risks. This review has been able to generate fresh perspectives on the anti-diabetic/anti-hyperglycemic/anti-obesity effect of phytochemicals. It has also brought into the focus that many phytochemicals demonstrating in vitro anti-obesogenic effects are yet to undergo in vivo investigation which could lead to potential phyto-molecules for dedicated anti-obesity action.

Adipogenesis as a Potential Anti-Obesity Target: A Review of Pharmacological Treatment and Natural Products

Obesity is recognized as a severe threat to overall human health and is associated with type 2 diabetes mellitus, dyslipidemia, hypertension, and cardiovascular diseases. Abnormal expansion of white adipose tissue involves increasing the existing adipocytes' cell size or increasing the number through the differentiation of new adipocytes. Adipogenesis is a process of proliferation and differentiation of adipocyte precursor cells in mature adipocytes. As a key process in determining the number of adipocytes, it is a possible therapeutic approach for obesity. Therefore, it is necessary to identify the molecular mechanisms involved in adipogenesis that could serve as suitable therapeutic targets. Reducing bodyweight is regarded as a major health benefit. Limited efficacy and possible side effects and drug interactions of available anti-obesity treatment highlight a constant need for finding novel efficient and safe anti-obesity ingredients. Numerous studies have recently investigated the inhibitory effects of natural products on adipocyte differentiation and lipid accumulation. Possible anti-obesity effects of natural products include the induction of apoptosis, cell-cycle arrest or delayed progression, and interference with transcription factor cascade or intracellular signaling pathways during the early phase of adipogenesis.

Therapeutic Effect of Guggulsterone in Primary Cultured Orbital Fibroblasts Obtained From Patients with Graves' Orbitopathy

Purpose

Inflammation, hyaluronan production, and adipogenesis are the main pathological events leading to Graves' orbitopathy (GO). Guggulsterone (GS), a phytosterol found in the resin of the guggul plant, is a well-known treatment for several inflammatory disorders, such as arthritis, obesity, and hyperlipidemia. Here we investigated the effects of GS treatment on GO pathology.

Methods

Using primary cultures of orbital fibroblasts from GO patients and non-GO controls, we examined the effects of GS on hyaluronan production and the production of proinflammatory cytokines induced by interleukin (IL)-1β, using real-time reverse transcription-polymerase chain reaction analysis, western blots, and enzyme-linked immunosorbent assays. Further, adipogenic differentiation was evaluated by quantification of Oil Red O staining and assessment of protein levels of peroxisome proliferator activator gamma (PPARγ), CCAAT-enhancer-binding proteins (C/EBP) α and β, and sterol regulatory element-binding protein-1 (SREBP-1).

Results

Treatment with noncytotoxic concentrations of GS resulted in the dose-dependent inhibition of IL-1β-induced inflammatory cytokines, including IL-6, IL-8, MCP-1, and COX-2, at both mRNA and protein levels. The hyaluronan level was also significantly suppressed by GS. Moreover, GS significantly decreased the formation of lipid droplets and expression of PPARγ, C/EBP α/β, and SREBP-1 in a dose-dependent manner. GS pretreatment attenuated the phosphorylation of nuclear factor-kappa B induced by IL-1β.

Conclusions

Our data show significant inhibitory effects of GS on inflammation, production of hyaluronan, and adipogenesis in orbital fibroblasts. To our knowledge, this is the first in vitro preclinical evidence of the therapeutic effect of GS in GO.

Endocrine-Mediated Mechanisms of Metabolic Disruption and New Approaches to Examine the Public Health Threat

Obesity and metabolic disorders are of great societal concern and generate substantial human health care costs globally. Interventions have resulted in only minimal impacts on disrupting this worsening health trend, increasing attention on putative environmental contributors. Exposure to numerous environmental contaminants have, over decades, been demonstrated to result in increased metabolic dysfunction and/or weight gain in cell and animal models, and in some cases, even in humans. There are numerous mechanisms through which environmental contaminants may contribute to metabolic dysfunction, though certain mechanisms, such as activation of the peroxisome proliferator activated receptor gamma or the retinoid x receptor, have received considerably more attention than less-studied mechanisms such as antagonism of the thyroid receptor, androgen receptor, or mitochondrial toxicity. As such, research on putative metabolic disruptors is growing rapidly, as is our understanding of molecular mechanisms underlying these effects. Concurrent with these advances, new research has evaluated current models of adipogenesis, and new models have been proposed. Only in the last several years have studies really begun to address complex mixtures of contaminants and how these mixtures may disrupt metabolic health in environmentally relevant exposure scenarios. Several studies have begun to assess environmental mixtures from various environments and study the mechanisms underlying their putative metabolic dysfunction; these studies hold real promise in highlighting crucial mechanisms driving observed organismal effects. In addition, high-throughput toxicity databases (ToxCast, etc.) may provide future benefits in prioritizing chemicals for in vivo testing, particularly once the causative molecular mechanisms promoting dysfunction are better understood and expert critiques are used to hone the databases. In this review, we will review the available literature linking metabolic disruption to endocrine-mediated molecular mechanisms, discuss the novel application of environmental mixtures and implications for in vivo metabolic health, and discuss the putative utility of applying high-throughput toxicity databases to answering complex organismal health outcome questions.

Guggulsterone Activates Adipocyte Beiging through Direct Effects on 3T3-L1 Adipocytes and Indirect Effects Mediated through RAW264.7 Macrophages

Background: Plant-derived phytochemicals have been of emerging interest as anti-obesity compounds due to their apparent effects on promoting reduced lipid accumulation in adipocytes. Despite such promising evidence, little is known about the potential mechanisms behind their anti-obesity effects. The aim of this study is to establish potential anti-obesity effects of the phytochemical guggulsterone (GS). Methods: Mature 3T3-L1 adipocytes were treated with GS, derived from the guggul plant native in northern India, to investigate its effects on mitochondrial biogenesis and adipocyte “beiging.” Further, to explore the relationship between macrophages and adipocytes, 3T3-L1s were treated with conditioned media from GS-treated RAW264.7 macrophages. Markers of mitochondrial biogenesis and beiging were measured by western blot. Results: GS treatment in adipocytes resulted in increased mitochondrial density, biogenesis (PGC1α and PPARγ), and increased markers of a beige adipocyte phenotype (UCP1, TBX1, and β-3AR). This upregulation in mitochondrial expression was accompanied by increases oxygen consumption. In GS-treated macrophages, markers of M2 polarization were elevated (e.g., arginase and IL-10), along with increased catecholamine release into the media. Lastly, 3T3-L1 adipocytes treated with conditioned media from macrophages induced a 167.8% increase in UCP1 expression, suggestive of a role of macrophages in eliciting an anti-adipogenic response to GS. Conclusions: Results from this study provide the first mechanistic understanding of the anti-obesity effects of GS and suggests a role for both direct GS-signaling and indirect stimulation of M2 macrophage polarization in this model.

Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 Cell Extracts Inhibit Adipogenesis in 3T3-L1 and HepG2 Cells

Some lactic acid bacteria (LAB) and their cellular components have antiobesity effects. In this study, we evaluated the antiadipogenic effects of a mixture of two LAB-Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032-using 3T3-L1 preadipocytes and HepG2 hepatocarcinoma cells. 3T3-L1 cells treated with a 1:1 ratio of HY7601 and KY1032 during differentiation showed reduced lipid accumulation by Oil Red O staining, as well as decreased leptin secretion and mRNA expression of peroxisome proliferator-activated receptor-γ and CCAAT/enhancer binding protein-α. HY7601 and KY1032 treatment also suppressed mitochondrial biogenesis and inhibited the expression of genes encoding mitochondrial transcription factors, as well as those related to fatty acid synthesis in HepG2 cells. The antiadipogenic effects of LAB were associated with the cell membrane fraction. These results demonstrate that a mixture of two LAB (HY7601 and KY1032) inhibits adipogenesis in preadipocytes and liver cells and is a potential therapeutic strategy for the treatment of obesity.

Googling the Guggul (Commiphora and Boswellia) for Prevention of Chronic Diseases

Extensive research during last 2 decades has revealed that most drugs discovered today, although costs billions of dollars for discovery, and yet they are highly ineffective in their clinical response. For instance, the European Medicines Agency has approved 68 anti-cancer drugs, and out of which 39 has reached the market level with no indication of increased survival nor betterment of quality of life. Even when drugs did improve survival rate compared to available treatment strategies, most of these were found to be clinically insignificant. This is a fundamental problem with modern drug discovery which is based on thinking that most chronic diseases are caused by alteration of a single gene and thus most therapies are single gene-targeted therapies. However, extensive research has revealed that most chronic diseases are caused by multiple gene products. Although most drugs designed by man are mono-targeted therapies, however, those designed by "mother nature" and have been used for thousands of years, are "multi-targeted" therapies. In this review, we examine two agents that have been around for thousands of years, namely "guggul" from Commiphora and Boswellia. Although we are all familiar with the search engine "google," this is another type of "guggul" that has been used for centuries and being explored for its various biological activities. The current review summarizes the traditional uses, chemistry, in vitro and in vivo biological activities, molecular targets, and clinical trials performed with these agents.

Combined effect of retinoic acid and calcium on the in vitro differentiation of human adipose-derived stem cells to adipocytes

CONTEXT

It has been shown that adipogenesis can be modulated by factors such as all-trans retinoic acid (ATRA) and calcium.

OBJECTIVE

To determine, the combined effect of ATRA and calcium on the differentiation of human adipose-derived stem cells (hADSCs).

METHODS

Mesenchymal stem cells (MSCs) were differentiated into the adipocytes by 0.5 and 1 µM of ATRA and 5 and 10 mM calcium separately or in combination. After MTS assay the differentiation of MSCs to adipocyte was evaluated, Oil Red O staining, GLUT4 concentration and gene expression of PPARG2, adiponectin, and GLUT4 were measured by Real-Time PCR.

RESULTS

Except 10 mM calcium treated group, other groups and more significantly combination treatments could reduce all adipocyte markers compared to the control.

CONCLUSION

These results suggest that ATRA and calcium together have significant inhibitory effect on adipogenesis that can be helpful for finding new mechanisms to prevent or control the adipogenesis.

Effect of Guggulsterone on the Expression of Adiponectin in 3T3-L1 Cells

Obesity is a worldwide threat, affecting both developed and developing countries. Guggulipid obtained from gum guggul is widely prescribed in Ayurveda for various medical conditions including obesity. The present study was designed to investigate the effect of guggulsterone on the expression of adiponectin, the adipokine that regulates glucose and fatty acid metabolism. 3T3-L1 cells were treated with guggulsterone E / Z isomer [(GE) /(GZ)] and mRNA levels of adiponectin as well as PPARγ (a transcription factor that regulates adiponectin expression) were monitored. Treatment of 3T3-L1 cells with GE / GZ during differentiation into adipocytes led to reduced mRNA levels of adiponectin. However, no effect on the mRNA levels of adiponectin was observed when fully differentiated adipocytes were treated with either GE or GZ.

Nonacidic Chemotype Possessing N-Acylated Piperidine Moiety as Potent Farnesoid X Receptor (FXR) Antagonists

Farnesoid X receptor (FXR) plays a major role in the control of cholesterol metabolism. Antagonizing transcriptional activity of FXR is an effective means to treat the relevant metabolic syndrome. Some of antagonists so far have the charged functions; however, they may negatively affect the pharmacokinetics. We describe herein a structure-activity relationship (SAR) exploration of nonacidic FXR antagonist 6 focusing on two regions in the structure and biological evaluation of nonacidic 10 with the characteristic N-acylated piperidine group obtained from SAR studies. As the robust affinity to FXR is feasible with our nonacidic analogue, 10 is among the most promising candidates for in vivo testing.

Total control of fat cells from adipogenesis to apoptosis using a xanthene analog

Overcrowded adipocytes secrete excess adipokines and cytokines under stress, which results in a deregulated metabolism. This negative response to stress increases the possibility of obesity and several of its associated diseases, such as cancer and atherosclerosis. Therefore, a reduction in the number of adipocytes may be a rational strategy to relieve the undesired expansion of adipose tissue. A newly synthesized xanthene analog, MI-401, was found to have two distinct effects on the regulation of the adipocyte’s life cycle. MI-401 efficiently down regulated the expression of transcription factors, PPARγ and C/EBPα, and lipogenesis proteins, FAS and FABP4. This down regulation resulted in the inhibition of adipogenesis. Without newly differentiated adipocytes, the total number of adipocytes will not increase. In addition to this inhibitory effect, MI-401 was able to actively kill mature adipocytes. It specifically triggered apoptosis in adipocytes at low micro molar concentration and spared preadipocytes and fibroblasts. These dual functionalities make MI-401 an effective agent in the regulation of the birth and death of adipocytes.

Phytochemicals as novel agents for the induction of browning in white adipose tissue

Obesity and its associated metabolic syndrome continue to be a health epidemic in westernized societies and is catching up in the developing world. Despite such increases, little headway has been made to reverse adverse weight gain in the global population. Few medical options exist for the treatment of obesity which points to the necessity for exploration of anti-obesity therapies including pharmaceutical and nutraceutical compounds. Defects in brown adipose tissue, a major energy dissipating organ, has been identified in the obese and is hypothesized to contribute to the overall metabolic deficit observed in obesity. Not surprisingly, considerable attention has been placed on the discovery of methods to activate brown adipose tissue. A variety of plant-derived, natural compounds have shown promise to regulate brown adipose tissue activity and enhance the lipolytic and catabolic potential of white adipose tissue. Through activation of the sympathetic nervous system, thyroid hormone signaling, and transcriptional regulation of metabolism, natural compounds such as capsaicin and resveratrol may provide a relatively safe and effective option to upregulate energy expenditure. Through utilizing the energy dissipating potential of such nutraceutical compounds, the possibility exists to provide a therapeutic solution to correct the energy imbalance that underlines obesity.

Fermented Platycodon grandiflorum Extract Inhibits Lipid Accumulation in 3T3-L1 Adipocytes and High-Fat Diet-Induced Obese Mice

The aim of this study was to investigate whether fermented Platycodon grandiflorum (FPG) inhibits lipid accumulation in 3T3-L1 adipocytes and mice with high-fat diet (HFD)-induced obesity. We evaluated the effect of FPG on antiadipogenic activity via regulation of peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα), as well as protein expression of their target genes, fatty acid binding protein 4 (FABP4). We further examined the antiobesity effects of FPG on HFD-induced obesity in mice. The FPG was orally administered to mice with a HFD at 50, 100, or 200 mg/kg/day for 8 weeks. Our results show that FPG significantly inhibited fat accumulation during 3T3-L1 adipogenesis through downregulating adipogenic transcript factors. Moreover, FPG markedly reduced the final body weight with a decrease in epididymal adipose tissue mass and adipocyte size compared with the untreated HFD-induced group. The effects of FPG on HFD-induced obesity were primarily responsible for inhibiting adipogenesis in adipose tissue and regulating lipid metabolism, such as through lipogenesis and fatty acid oxidation. Additionally, FPG ameliorated serum total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels. Hence, FPG may be an alternative treatment for controlling obesity through downregulating lipid accumulation.

Potential of Natural Products in the Inhibition of Adipogenesis through Regulation of PPARγ Expression and/or Its Transcriptional Activity

Obesity is a global health problem characterized as an increase in the mass of adipose tissue. Adipogenesis is one of the key pathways that increases the mass of adipose tissue, by which preadipocytes mature into adipocytes through cell differentiation. Peroxisome proliferator-activated receptor γ (PPARγ), the chief regulator of adipogenesis, has been acutely investigated as a molecular target for natural products in the development of anti-obesity treatments. In this review, the regulation of PPARγ expression by natural products through inhibition of CCAAT/enhancer-binding protein β (C/EBPβ) and the farnesoid X receptor (FXR), increased expression of GATA-2 and GATA-3 and activation of the Wnt/β-catenin pathway were analyzed. Furthermore, the regulation of PPARγ transcriptional activity associated with natural products through the antagonism of PPARγ and activation of Sirtuin 1 (Sirt1) and AMP-activated protein kinase (AMPK) were discussed. Lastly, regulation of mitogen-activated protein kinase (MAPK) by natural products, which might regulate both PPARγ expression and PPARγ transcriptional activity, was summarized. Understanding the role natural products play, as well as the mechanisms behind their regulation of PPARγ activity is critical for future research into their therapeutic potential for fighting obesity.

Guggulsterone and Its Role in Chronic Diseases

Guggulsterone is a plant sterol derived from gum resin of Commiphora wightii. The gum resin from guggul plants has been used for thousand years in Ayurveda to treat various disorders, including internal tumors, obesity, liver disorders, malignant sores and ulcers, urinary complaints, intestinal worms, leucoderma, sinuses, edema, and sudden paralytic seizures. Guggulsterone has been identified a bioactive components of this gum resin. This plant steroid has been reported to work as an antagonist of certain nuclear receptors, especially farnesoid X receptor, which regulates bile acids and cholesterol metabolism. Guggulsterone also mediates gene expression through the regulation of transcription factors, including nuclear factor-kappa B and signal transducer and activator of transcription 3, which plays important roles in the development of inflammation and tumorigenesis. Guggulsterone has been shown to downregulate the expression of proteins involved in anti-apoptotic, cell survival, cell proliferation, angiogenic, metastatic, and chemoresistant activities in tumor cells. This review aimed to clarify the cell signal pathways targeted by guggulsterone and the bioactivities of guggulsterone in animal models and humans.

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.

Group IIE secretory phospholipase A2 regulates lipolysis in adipocytes

OBJECTIVE

To examine the function of group IIE secretory phospholipase A(2) (sPLA(2) -IIE) in adipocytes and to explore the possible signaling mechanism involved.

METHODS

The expression of sPLA(2) -IIE was demonstrated using real-time PCR and Western blot analysis. Lipid accumulation was evaluated via the measurement of cellular triglycerides (TG). Lipolysis was quantified by measuring the release of free glycerol. The expressions of M-type sPLA(2) receptor (PLA(2) R1) and the genes encoding adipogenic proteins were measured using real-time PCR. The activities of the Janus kinase 2 (JAK2), extracellular regulated protein kinase (ERK), and hormone-sensitive lipase (HSL) were determined using Western blot.

RESULTS

sPLA(2) -IIE(-/-) mice gained significantly more epididymal fat than wild-type (WT) mice. When treated with adipogenic stimuli ex vivo, stromal vascular cells isolated from the adipose tissue of sPLA(2) -IIE(-/-) mice accumulated significantly more TG than those from WT mice. Conversely, a significant reduction in lipid accumulation and an increase of free glycerol were observed in OP9 cells overexpressing sPLA(2) -IIE and in 3T3-L1 cells treated with sPLA(2) -IIE protein. Moreover, sPLA(2) -IIE significantly induced adipocyte glycerol release and HSL activity, which was inhibited by PD98059, an ERK inhibitor.

CONCLUSIONS

sPLA(2) -IIE regulates lipolysis in adipocytes, likely through the ERK/HSL signaling pathway.

The autophagic inhibitor 3-methyladenine potently stimulates PKA-dependent lipolysis in adipocytes

BACKGROUND AND PURPOSE The class III PI3K inhibitor, 3-methyladenine (3-MA), is commonly used to selectively block autophagy. Recent findings suggest a strong relationship between autophagy and lipid turnover. Here, we explore the effect of 3-MA on adipocyte lipolysis. EXPERIMENTAL APPROACH Assays were performed in 3T3-L1 cells. Cells were treated with 3-MA and wortmannin, a pan PI3K and autophagy inhibitor. Pharmacological and genetic manipulation of endogenous autophagic and lipolytic pathways was used to ascertain the contribution of 3-MA to the observed effects on lipolysis. KEY RESULTS 3T3-L1 cells that were exposed to 3-MA showed a consistent increase in lipolysis, approximately 50% over basal levels. The effect of 3-MA was not secondary to autophagic inhibition as treatment of 3T3-L1 cells with wortmannin yielded no such changes. Dosing and time course experiments showed that 3-MA's ability to activate lipolysis was more sensitive than its inhibitory effect on autophagy. Knockdown of adipose triglyceride lipase (ATGL) negated the stimulatory effect of 3-MA by >90%, indicating that 3-MA enhanced ATGL-dependent hydrolysis of triacylglycerols. Additionally, the lipolytic effect of 3-MA was dependent on the activation of PKA and 3-MA induced a rapid and potent elevation of intracellular cAMP levels in adipocytes. CONCLUSIONS AND IMPLICATIONS Cumulatively, we show that 3-MA potently modulated a cellular mechanism and its underlying signalling pathways not associated with autophagy. Furthermore, we describe a novel stimulatory effect on a major signalling pathway. Our findings provide valuable information to studies employing 3-MA as a specific inhibitor for PI3K and autophagy.

Caspase induction and BCL2 inhibition in human adipose tissue: a potential relationship with insulin signaling alteration

OBJECTIVE

Cell death determines the onset of obesity and associated insulin resistance. Here, we analyze the relationship among obesity, adipose tissue apoptosis, and insulin signaling.

RESEARCH DESIGN AND METHODS

The expression levels of initiator (CASP8/9) and effector (CASP3/7) caspases as well as antiapoptotic B-cell lymphoma (BCL)2 and inflammatory markers were assessed in visceral (VAT) and subcutaneous (SAT) adipose tissue from patients with different degrees of obesity and without insulin resistance or diabetes. Adipose tissue explants from lean subjects were cultured with TNF-α or IL-6, and the expression of apoptotic and insulin signaling components was analyzed and compared with basal expression levels in morbidly obese subjects.

RESULTS

SAT and VAT exhibited increased CASP3/7 and CASP8/9 expression levels and decreased BCL2 expression with BMI increase. These changes were accompanied by increased inflammatory cytokine mRNA levels and macrophage infiltration markers. In obese subjects, CASP3/7 activation and BCL2 downregulation correlated with the IRS-1/2-expression levels. Expression levels of caspases, BCL2, p21, p53, IRS-1/2, GLUT4, protein tyrosine phosphatase 1B, and leukocyte antigen-related phosphatase in TNF-α- or IL-6-treated explants from lean subjects were comparable with those found in adipose tissue samples from morbidly obese subjects. These insulin component expression levels were reverted with CASP3/7 inhibition in these TNF-α- or IL-6-treated explants.

CONCLUSIONS

Body fat mass increase is associated with CASP3/7 and BCL2 expression in adipose tissue. Moreover, this proapoptotic state correlated with insulin signaling, suggesting its potential contribution to the development of insulin resistance.

Proteomic analysis of rosiglitazone and guggulsterone treated 3T3-L1 preadipocytes

Adipogenesis is the differentiation of preadipocytes to adipocytes which is marked by the accumulation of lipid droplets. Adipogenic differentiation of 3T3-L1 cells is achieved by exposing the cells to Insulin, Dexamethasone and IBMX for 5-7 days. Thiazolidinedione drugs, like rosiglitazone are potent insulin sensitizing agents and have been shown to enhance lipid droplet formation in 3T3-L1 cells, a model cell line for preadipocyte differentiation. Guggulsterone is a natural drug extracted from the gum resin of tree Commiphora mukul. Guggulsterone has been shown to inhibit adipogenesis and induce apoptosis in 3T3-L1 cells. In this study we treated the 3T3-L1 preadipocytes with rosiglitazone and guggulsterone and assessed the protein expression profile using 2D gel electrophoresis-based proteomics to find out differential target proteins of these drugs. The proteins that were identified upon rosiglitazone treatment generally regulate cell proliferation and/or exhibit anti-inflammatory effect which strengthens its differentiation-inducing property. Guggulsterone treatment resulted in the identification of the apoptosis-inducing proteins to be up regulated which rightly is in agreement with the apoptosis-inducing property of guggulsterone in 3T3-L1 cells. Some of the proteins identified in our proteomic screen such as Galectin1, AnnexinA2 & TCTP were further confirmed by Real Time qPCR. Thus, the present study provides a better outlook of proteins being differentially regulated/expressed upon treatment with rosiglitazone and guggulsterone. The detailed study of the differentially expressed proteins identified in this proteomic screen may further provide the better molecular insight into the mode of action of these anti-diabetic drugs rosiglitazone and guggulsterone.

Inhibitory effect of andrographolide in 3T3-L1 adipocytes differentiation through the PPARγ pathway

Andrographolide (AG), an active compound found in Andrographis paniculate Nees, has been shown to exert anti-inflammatory, anticancer and anti-hyperglycemic effects. However, its biological activities against obesity have not been reported. The purpose of this study was to investigate the effect of AG on the differentiation of 3T3-L1 preadipocytes. We found AG significantly inhibited not only on adipocyte differentiation induced by standard adipogenic agents and MDI, but also on the adipogenesis-related transcription factor, peroxisome proliferator-activated receptor γ (PPARγ), as well as the expressions of the PPARγ targeted genes, such as CD36, LPL, FAS and other adiocyte markers. Taken together, our data showed AG inhibited the early stage of adipogenic differentiation, in part via the inhibition of PPARγ-dependent mechanisms.

Pharmacological properties of guggulsterones, the major active components of gum guggul

Oleo gum resin secreted by Commiphora mukul, also known as gum guggul, has been used widely as an ayurvedic drug. Commiphora mukul is a short thorny shrub that is native to the Indian subcontinent. Oleo gum resin extracted by incision of the bark is a very complex mixture of gum, minerals, essential oils, terpenes, sterols, ferrulates, flavanones and sterones. Its active constituents, the Z- and E-guggulsterones, have been demonstrated to exhibit their biological activities by binding to nuclear receptors and modulating the expression of proteins involved in carcinogenic activities. Guggulsterones have also been reported to regulate gene expression by exhibiting control over other molecular targets including transcription factors such as nuclear factor (NF)-κB, signal transducer and activator of transcription (STAT) and steroid receptors. Considerable scientific evidence indicates the use of gum guggul as a therapeutic agent in the treatment of inflammation, nervous disorders, hyperlipidaemia and associated cardiac disorders such as hypertension and ischaemia, skin disorders, cancer and urinary disorders. This review highlights the taxonomic details, phytochemical properties and pharmacological profile of gum guggul.

Novel stereoselective synthesis and chromatographic evaluation of E-guggulsterone

A new stereoselective synthesis of E-guggulsterone is described starting from androsten-3,17-dione. Protection of the ring A enonic system, followed by regioselective Wittig reaction and C-16 oxidation, affords E-guggulsterone in good yields and high stereoselectivity, making this approach easily accessible and scalable. Moreover, an original normal-phase HPLC method enabling the fast quantitation of the guggulsterone isomeric purity, combined with the suitability for sampling procedures, is detailed. The relying upon the cellulose-based Chiralpak IB column and the chloroform as the "non-standard" component of the eluent mixture, allows to get profitably high chromatographic performances.

Targeting adipocyte apoptosis: a novel strategy for obesity therapy

Obesity is an increasing world problem that may cause several metabolic complications including insulin resistance, hyperlipidemia, hypertension, and atherosclerosis. Development of therapeutic drugs for obesity has been proven difficult. Current strategies for weight reduction are inhibition of food intake through the central nervous system or blocking the absorption of lipids in the gut. These therapies have many side effects, so new treatments are urgently needed. Fat loss could also be achieved through a decrease in the size and number of adipocytes through apoptosis. Apoptosis is a normal phenomenon of cell death for the purpose of maintaining homeostasis. Induction of apoptosis is a reasonable way to remove adipocytes in obese patients. It is reported that several adipokines and natural products play roles in induction of adipocyte apoptosis. Here we review the recent progress of the roles and mechanisms of adipocyte apoptosis induced by leptin, tumor necrosis factor-α (TNF-α), and natural compounds.

Cannabinoid type 1 receptor mediates depot-specific effects on differentiation, inflammation and oxidative metabolism in inguinal and epididymal white adipocytes

Objective:

The endocannabinoid system is a major component in the control of energy metabolism. Cannabinoid 1 (CB1)-receptor blockade induces weight loss and reduces the risk to develop the metabolic syndrome with its associated cardiovascular complications. These effects are mediated by central and peripheral pathways. Interestingly, weight loss is mainly achieved by a reduction of visceral fat mass. We analyzed fat depot-specific differences on adipocyte differentiation, inflammation and oxidative metabolism in CB1-receptor knockout cells.

Materials and methods:

We used newly generated epididymal/inguinal adipose cell lines from CB1-receptor knockout mice. Differences in differentiation were measured by fat-specific Oil Red O staining and quantitative analysis of key differentiation markers. Induction of apoptosis was evaluated by cell death detection and investigation of p53 phosphorylation. Inflammation markers were quantified by real-time PCR. For analyzing the process of transdifferentiation we measured oxygen consumption and mitochondrial biogenesis.

Results:

Differentiation was reduced in visceral adipocytes from CB1-receptor knockout mice as compared with wild-type controls. Moreover, we found an induction of apoptosis in these cells. In contrast, subcutaneous adipocytes from CB1-receptor knockout mice showed an accelerated differentiation and a reduced rate of apoptosis. Inflammation was increased in visceral fat cells, as analyzed by the expression pattern of interleukin-6, monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor-α, whereas in subcutaneous adipocytes these markers were decreased. Furthermore, subcutaneous CB1-receptor knockout cells were more sensitive toward a conversion into a brown fat phenotype. Uncoupling protein-1 as well as PGC-1α expression was significantly elevated. This was accompanied by an increase in mitochondrial biogenesis and oxygen consumption.

Conclusion:

In conclusion, we found depot-specific effects on differentiation, apoptosis, inflammation and oxidative metabolism in CB1-receptor knockout cells. Thus, CB1-receptor-mediated pathways differentially target adipose tissue depots to a dual effect that minimizes cardiometabolic risk, on the one hand, by diminishing visceral fat, and that enhances thermogenesis in subcutaneous adipocytes, on the other.

The inhibitory effect of Lactobacillus plantarum KY1032 cell extract on the adipogenesis of 3T3-L1 Cells

Some probiotics and their cell components are known to modulate lipid metabolism in vitro and/or in vivo. This study was carried out to investigate possible anti-adipogenic action of a probiotic cell extract, Lactobacillus plantarum KY1032 cell extract (KY1032-CE), in vitro using 3T3-L1 cells. Lipid regulation in the cell culture system was assessed by AdipoRed assay and Oil red O staining of intracellular lipids and real-time polymerase chain reaction and western blot analysis of adipogenesis-related factors. AdipoRed assay revealed that KY1032-CE treatment significantly decreased lipid accumulation in maturing 3T3-L1 preadipocytes in a dose-dependent manner. Oil red O staining demonstrated that KY1032-CE reduced the number of lipid-containing rounded cells. KY1032-CE down-regulated the mRNA and protein expression of four adipocyte-specific genes: peroxisome proliferator-activated receptor-γ2, CCAAT/enhancer binding protein-α, fatty acid synthase, and adipocyte-fatty acid binding protein. Accordingly, these results indicate that KY1032-CE can reduce fat mass by modulating adipogenesis in maturing preadipocytes. Further studies are needed to elucidate its mode of actions in efficacy tests of KY1032-CE in vivo.

Phytochemicals and adipogenesis

Obesity is an increasing health problem all over the world. Phytochemicals are potential agents to inhibit differentiation of preadipocytes, stimulate lipolysis, and induce apoptosis of existing adipocytes, thereby reducing the amount of adipose tissue. Flavonoids and stilbenoids represent the most researched groups of phytochemicals with regards to their effect on adipogenesis, but there are also a number of in vitro and in vivo studies with phenolic acids, alkaloids, and vitamins, as well as other plant compounds. Although phytochemicals like epigallocatechin-3-gallate, genistein, and resveratrol reduce lipid accumulation and induce adipocyte apoptosis in vitro and reduce body weight and adipose tissues mass in animal models of diet-induced obesity, well-conducted clinical trials are lacking. Pharmacological doses are often used in vitro and when applied in physiological doses in animals or humans, the phytochemicals are often ineffective in affecting adipogenesis. However, by combining several phytochemicals or using them as templates for synthesizing new drugs, there is a large potential in targeting adipogenesis using phytochemicals.

An active extract of Lindera obtusiloba inhibits adipogenesis via sustained Wnt signaling and exerts anti-inflammatory effects in the 3T3-L1 preadipocytes

Obesity, the related metabolic syndrome and associated liver diseases represent an epidemic problem and demand for effective therapeutic strategies. In this regard, natural compounds derived from Oriental medicine such as green tea polyphenols influencing adipogenesis attract growing attention. In Korea, an aqueous extract from the Japanese spice bush Lindera obtusiloba is traditionally used for treatment of inflammation and prevention of liver damage. We here investigated effects of the L. obtusiloba extract on cell growth, apoptosis, Wnt signaling and differentiation of (im)mature adipocytes using 3T3-L1, an established cell line for studying adipogenesis. L. obtusiloba extract reduced the de novo DNA synthesis of 3T3-L1 preadipocytes in a concentration dependent manner with an IC(50) of ∼135 μg/ml paralleled by induction of caspase 3/7 mediated apoptosis. Hormone-induced 3T3 L1 differentiation in the presence of L. obtusiloba extract resulted in a reduced accumulation of intracellular lipid droplets by 70%, in down-regulated expression of the adipogenesis-associated proteins glucose transporter-4 and vascular endothelial growth factor, in reduced secretion of the proadipogenic matrix metalloproteinase-2, and in dampened phosphorylation of the Wnt pathway effector protein β-catenin with subsequent diminished expression of the peroxisome proliferator-activated receptor-γ. Treatment of mature adipocytes with L. obtusiloba extract also significantly reduced intracellular lipid droplets. In addition to this strong interference of L. obtusiloba extract with adipogenesis, L. obtusiloba extract exerted anti-inflammatory effects. L. obtusiloba extract significantly attenuated lipopolysaccharide- and tumor necrosis factor α-induced secretion of IL-6 by preadipocytes, thus influencing insulin resistance and inflammatory state characterizing obesity. In conclusion, extracts of L. obtusiloba should be evaluated as a potential complementary treatment option for obesity associated with the metabolic syndrome.

Anti-obesity effects of xanthohumol plus guggulsterone in 3T3-L1 adipocytes

Xanthohumol (XN) and guggulsterone (GS) have each been shown to inhibit adipogenesis and induce apoptosis in adipocytes. In the present study effects of the combination of XN + GS on 3T3-L1 adipocyte apoptosis and adipogenesis were investigated. Mature adipocytes were treated with XN and GS individually and in combination. XN and GS individually decreased cell viability, but XN + GS caused an enhanced decrease in viability and potentiated induction of apoptosis. Likewise, XN + GS caused a potentiated increase in caspase-3/7 activation, whereas neither of the compounds showed any effect individually. In addition, western blot analysis revealed that XN + GS increased Bax expression and decreased Bcl-2 expression, whereas individual compounds did not show any significant effect. XN and GS both decreased lipid accumulation. Individually, XN at 1.5 microM and GS at 3.12 microM decreased lipid accumulation by 26 +/- 4.5% (P < .001) each, whereas XN1.5 + GS3.12 decreased lipid accumulation by 78.2 +/- 1.8% (P < .001). Moreover, expression of the adipocyte-specific proteins was down-regulated with XN1.5 + GS3.12, but no effect was observed with the individual compounds. Finally, XN + GS caused an enhanced stimulation of lipolysis. Thus, combination of XN and GS is more potent in exerting anti-obesity effects than additive effects of the individual compounds.

Effects of guggulsterone isolated from Commiphora mukul in high fat diet induced diabetic rats

Sedentary lifestyle, consumption of energy-rich diet, obesity and longer lifespan are some of the major reasons for the rise of metabolic disorders like type II diabetes, obesity, hypertension and dyslipidemia among people of various age groups. High fat diet induced diabetic rodent models resembling type II diabetic condition in human population were used to assess the anti-diabetic and hypolipidemic activity of guggulsterone (isolated from Commiphora mukul resin). Four groups of rats were fed high fat diet, for 16 weeks. On feeding the normal rats with fat rich diet they showed increased serum glucose, cholesterol and triglyceride levels along with increase in insulin resistance significantly (p<0.05) in comparison to control animals. Different biochemical parameters like GTT, glycogen content, glucose homeostatic enzymes (like glucose-6-phosphatase, hexokinase), insulin release in vivo and expression profiles of various genes involved in carbohydrate and lipid metabolism clearly demonstrated the hypoglycemic effect of this extract. Guggulsterone demonstrated a differential effect with a significantly improved PPARgamma expression and activity in in vivo and in vitro conditions, respectively. However, it inhibited 3T3-L1 preadipocytes differentiation in vitro. The results presented here suggest that the guggulsterone has both hypoglycemic and hypolipidemic effect which can help to cure type II diabetes.

Withaferin A induces apoptosis and inhibits adipogenesis in 3T3-L1 adipocytes

Withaferin A (WA), a highly oxygenated steroidal lactone that is found in the medicinal plant Withania somnifera (also called ashwagandha) has been reported to have anti-tumor, anti-angiogenesis, and pro-apoptotic activity. We investigated the effects of WA on viability, apoptosis and adipogenesis in 3T3-L1 adipocytes. Pre- and post-confluent preadipocytes and mature adipocytes were treated with WA (1-25 microM) up to 24 hrs. Viability and apoptosis were measured by CellTiter-Blue Cell Viability Assay and single strand DNA ELISA Assay, respectively. WA decreased viability and induced apoptosis in all stages of cells. Induction of apoptosis by WA in mature adipocytes was mediated by increased ERK1/2 phosphorylation and altered Bax and Bcl2 protein expression. The effect of WA on adipogenesis was examined by AdipoRed Assay after treating with WA (0.1-1 microM) during the differentiation period. WA decreased lipid accumulation in a dose-dependent manner and decreased the expression of peroxisome proliferator-activated receptor gamma, CCAAT/enhancer binding protein alpha and adipocyte fatty acid binding protein. The effects on apoptosis and lipid accumulation were also confirmed with Hoechst staining and Oil Red O staining, respectively. These results show that WA acts on adipocytes to reduce cell viability and adipogenesis and also induce apoptosis.

Effect of xanthohumol and isoxanthohumol on 3T3-L1 cell apoptosis and adipogenesis

Xanthohumol (XN), the chalcone from beer hops has several biological activities. XN has been shown to induce apoptosis in cancer cells and also has been reported to be involved in lipid metabolism. Based on these studies and our previous work with natural compounds, we hypothesized that XN and its isomeric flavanone, isoxanthohumol (IXN), would induce apoptosis in adipocytes through the mitochondrial pathway and would inhibit maturation of preadipocytes. Adipocytes were treated with various concentrations of XN or IXN. In mature adipocytes both XN and IXN decreased viability, increased apoptosis and increased ROS production, XN being more effective. Furthermore, the antioxidants ascorbic acid and 2-mercaptoethanol prevented XN and IXN-induced ROS generation and apoptosis. Immunoblotting analysis showed an increase in the levels of cytoplasmic cytochrome c and cleaved poly (ADP-ribose) polymerase (PARP) by XN and IXN. Concomitantly, we observed activation of the effectors caspase-3/7. In maturing preadipocytes both XN and IXN were effective in reducing lipid content, XN being more potent. Moreover, the major adipocyte marker proteins such as PPARgamma, C/EBPalpha, and aP2 decreased after treatment with XN during the maturation period and that of DGAT1 decreased after treatment with XN and IXN. Taken together, our data indicate that both XN and IXN inhibit differentiation of preadipocytes, and induce apoptosis in mature adipocytes, but XN is more potent.