Enhanced pro-apoptotic and anti-adipogenic effects of genistein plus guggulsterone in 3T3-L1 adipocytes

Genistein improves systemic metabolism and enhances cold resistance by promoting adipose tissue beiging

Genistein, a naturally occurring phytoestrogen and a member of the large class of compounds known as isoflavones, exerts protective effects in several diseases. Recent studies indicate that genistein plays a critical role in controlling body weight, obesity-associated insulin resistance, and metabolic disorders, but its target organs in reversing obesity and related pathological conditions remain unclear. In this study, we showed that mice supplemented with 0.2% genistein in a high-fat diet for 12 weeks showed enhanced metabolic homeostasis, including reduced obesity, improved glucose uptake and insulin sensitivity, and alleviated hepatic steatosis. We also observed a beiging phenomenon in the white adipose tissue and reversal of brown adipose tissue whitening in these mice. These changes led to enhanced resistance to cold stress. Altogether, our data suggest that the improved metabolic profile in mice treated with genistein is likely a result of enhanced adipose tissue function.

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.

Flavonoids as antiobesity agents: A review

Obesity is a global health problem that affects all age groups in both developing and developed countries. In recent years, the prevalence of overweight and obesity has reached pandemic levels, resulting in a dramatic increase in the incidence of various comorbidities, such as cardiovascular diseases, type 2 diabetes, and cancer, consequently leading to massive health and socioeconomic burdens. Together with lifestyle changes, antiobesity pharmacotherapy is gaining momentum as an adjunctive treatment. However, the available pharmacological approaches have limited use owing to either significant adverse effects or low efficacy. Over the years, natural products have been an important source of lead compounds for drug discovery. Among these, flavonoids are associated with important biological effects and health-promoting activities. In this review, we discuss the modulatory effects of flavonoids on obesity and their potential mechanisms of action. The literature strongly suggests that most common flavonoids demonstrate a pronounced effect on obesity as shown by their ability to lower body weight, fat mass, and plasma triglycerides/cholesterol, both in in vitro and in vivo models. The impact of flavonoids on obesity can be observed through different mechanisms: reducing food intake and fat absorption, increasing energy expenditure, modulating lipid metabolism, or regulating gut microbiota profile. A better understanding of the known antiobesity mechanisms of flavonoids will enable their potential use to treat this medical condition. Therefore, this review focuses on the putative biological mechanisms through which flavonoids may prevent or treat obesity and highlights new perspectives on future pharmacological use.

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.

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.

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.

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.

The combination of resveratrol and conjugated linoleic acid attenuates the individual effects of these molecules on triacylglycerol metabolism in adipose tissue

PURPOSE

The combination of resveratrol + conjugated linoleic acid (RSV + CLA) did not show the body fat-lowering effect exhibited by these molecules when administered separately. This study aimed to find metabolic explanations for this situation in an experimental model of diet-induced obesity.

METHODS

Thirty-six male Wistar rats were divided into four groups: rats treated with saline (control), resveratrol (RSV), conjugated linoleic acid (CLA) and a combination of these molecules (RSV + CLA).

RESULTS

Rats treated with RSV + CLA did not show the reduction in heparin-releasable lipoprotein lipase (HR-LPL) and fatty acid synthase activities observed in RSV group or the increased HSL expression found in RSV and CLA groups. These animals showed reduced sirtuin 1 expression and CLA isomer amounts in adipose tissue. Finally, intracellular Ca(2+) concentration was increased.

CONCLUSION

The attenuation of the effects induced in adipose tissue triacylglycerol metabolism by RSV and CLA separately, such as the decrease in lipogenesis and fatty acid uptake and the increase in lipolysis, contributes to explain the lack of body fat-lowering effect of the combination RSV + CLA.

Artemisinic acid is a regulator of adipocyte differentiation and C/EBP δ expression

Adipocyte dysfunction is associated with the development of obesity. In this study, artemisinic acid, which was isolated from Artemisia annua L., inhibited adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells (hAMSCs) and its mechanism of action was determined. The mRNA levels of peroxidase proliferation-activated receptor (PPAR) γ and CCAAT/enhancer binding protein (C/EBP) α, late adipogenic factors, were reduced by artemisinic acid. Moreover, the mRNA levels of the PPAR γ target genes lipoprotein lipase, CD36, adipocyte protein, and liver X receptor were down-regulated by artemisinic acid. Artemisinic acid reduced expression of the C/EBP δ gene without impacting C/EBP β. In addition, attempts to elucidate a possible mechanism underlying the artemisinic acid-mediated effects revealed that reduced expression of the C/EBP δ gene was mediated by inhibiting Jun N-terminal kinase (JNK). Additionally, artemisinic acid also reduced the expression of the adipogenesis-associated genes glucose transporter-4 and vascular endothelial growth factor. In addition to the interference of artemisinic acid with adipogenesis, artemisinic acid significantly attenuated tumor necrosis factor-α-induced secretion of interleukin-6 by undifferentiated hAMSCs, thus influencing insulin resistance and the inflammatory state characterizing obesity. Taken together, these findings indicate that inhibiting adipogenic differentiation of hAMSCs by artemisinic acid occurs primarily through reduced expression of C/EBP δ, which is mediated by the inhibition of JNK and suggest that aremisinic acid may be used as a complementary treatment option for obesity associated with metabolic syndrome.

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.

High-fat diet-induced adipocyte cell death occurs through a cyclophilin D intrinsic signaling pathway independent of adipose tissue inflammation

OBJECTIVE

Previous studies have demonstrated that mice fed a high-fat diet (HFD) develop insulin resistance with proinflammatory macrophage infiltration into white adipose tissue. Concomitantly, adipocytes undergo programmed cell death with the loss of the adipocyte-specific lipid droplet protein perilipin, and the dead/dying adipocytes are surrounded by macrophages that are organized into crown-like structures. This study investigated whether adipocyte cell death provides the driving signal for macrophage inflammation or if inflammation induces adipocyte cell death.

RESEARCH DESIGN AND METHODS

Two knockout mouse models were used: granulocyte/monocyte-colony stimulating factor (GM-CSF)-null mice that are protected against HFD-induced adipose tissue inflammation and cyclophilin D (CyP-D)-null mice that are protected against adipocyte cell death. Mice were fed for 4-14 weeks with a 60% HFD, and different markers of cell death and inflammation were analyzed.

RESULTS

HFD induced a normal extent of adipocyte cell death in GM-CSF-null mice, despite a marked reduction in adipose tissue inflammation. Similarly, depletion of macrophages by clodronate treatment prevented HFD-induced adipose tissue inflammation without any affect on adipocyte cell death. However, CyP-D deficiency strongly protected adipocytes from HFD-induced cell death, without affecting adipose tissue inflammation.

CONCLUSIONS

These data demonstrate that HFD-induced adipocyte cell death is an intrinsic cellular response that is CyP-D dependent but is independent of macrophage infiltration/activation.

Effect of resveratrol on fat mobilization

Higher levels of body fat are associated with increased risk for development of numerous adverse health conditions. Phytochemicals are potential agents to inhibit differentiation of preadipocytes, stimulate lipolysis, and induce apoptosis of existing adipocytes, thereby reducing adipose tissue mass. Resveratrol decreased adipogenesis and viability in maturing preadipocytes; these effects were mediated not only through down-regulating adipocyte specific transcription factors and enzymes but also by genes that modulate mitochondrial function. Additionally, resveratrol increased lipolysis and reduced lipogenesis in mature adipocytes. In addition, combining resveratrol with other natural products produced synergistic activities from actions on multiple molecular targets in the adipocyte life cycle. Treatment of mice with resveratrol alone was shown to improve resistance to weight gain caused by a high-fat diet. Moreover, dietary supplementation of aged ovariectomized rats with a combination of resveratrol and vitamin D, quercetin, and genistein not only decreased weight gain but also inhibited bone loss. Combining several phytochemicals, including resveratrol, or using them as templates for synthesizing new drugs, provides a large potential for using phytochemicals to target adipocyte adipogenesis, apoptosis, and lipolysis.

Soy isoflavones, Mediterranean diet, and physical exercise in postmenopausal women with insulin resistance

OBJECTIVE

The aim of this study was to evaluate whether a standard dose of 40 mg of soy isoflavones prescribed in routine clinical practice for treatment of menopausal symptoms has some influence on glucose homeostasis in postmenopausal women with insulin resistance (IR).

METHODS

A total of 116 postmenopausal women with IR were randomly assigned to a group of Mediterranean diet and physical exercise (control group) or a group of Mediterranean diet, physical exercise, and daily oral ingestion of 40 mg of soy isoflavones (soy isoflavones group). Anthropometric measures, Kupperman Index values, Cervantes Scale score, and blood samples for glucose, insulin, lipid profile, creatinine, uric acid, homocysteine, folic acid, vitamin B12, selenium, and estradiol were determined at baseline and at intervals of 6, 12, 18, and 24 months.

RESULTS

Mean homeostasis model assessment of IR (HOMA-IR) values remained unchanged from the baseline in the control group but steadily decreased in the soy isoflavones group at 6 months (P = 0.042). There were no statistically significant differences between both groups in mean HOMA-IR scores at baseline, but statistically significantly lower values were found in the soy isoflavones group at 6 months (P = 0.009), 12 months (P = 0.011), 18 months (P = 0.018), and 24 months (P = 0.012). Changes in HOMA-IR values were also clearly related to body mass index (P < 0.001), abdominal circumference (P < 0.001), and treatment (P = 0.044) when a linear regression analysis was carried out.

CONCLUSIONS

Daily intake of 40 mg of soy isoflavones together with a Mediterranean diet and exercise reduced IR in postmenopausal women who had IR in the first place. It was significantly better than lifestyle changes alone. If corroborated, this may be a useful intervention for these women.

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.