Ursolic acid inhibits adipogenesis in 3T3-L1 adipocytes through LKB1/AMPK pathway

Immature Citrus unshiu fruit extracts inhibit adipogenesis in 3T3-L1 adipocytes via AMPK and MAPK signaling pathways

In Korea, immature citrus fruits have been extensively explored for their potential utility as functional bio-health materials owing to their various bioactive properties. However, the specific mechanisms by which they exert inhibitory effects on adipogenesis remain unclear. Therefore, this study aimed to examine the anti-obesity effects of 70% ethanol extracts of immature Citrus unshiu fruits and their solvent fractions (n-hexane, ethyl acetate, n-butanol, and water) on 3T3-L1 cells, as well as to explore the underlying molecular mechanisms. Additionally, this study was conducted to identify the bioactive components responsible for the anti-obesity effects. Among the fractions, the hexane fraction exhibited the most potent inhibitory effect on lipid accumulation in 3T3-L1 cells without inducing cytotoxicity. Notably, this effect was concentration-dependent. This fraction also inhibited adipogenesis during the differentiation of 3T3-L1 preadipocytes by downregulating the expression of CCAAT/enhancer-binding proteins (C/EBP), peroxisome proliferator-activated receptor-γ (PPARγ), sterol regulatory element-binding protein (SREBP), fatty acid synthase (FAS), and fatty acid binding protein 4 (FABP4). Moreover, the hexane fraction modulated the activity of AMP-activated protein kinase (AMPK) and mitogen-activated protein kinase (MAPK), both of which play critical roles in lipid metabolism. Specifically, it induced AMPK activation while downregulating MAPK signaling. Phytochemical analysis identified phytol, hexatriacontane, tangeretin, and nobiletin as the main bioactive components responsible for the observed anti-obesity effects of ICE. Overall, our results revealed that ICE exhibited notable anti-obesity activity by targeting the AMPK and MAPK signaling pathways, highlighting its potential as a natural therapeutic agent for obesity management.

Cross-sectional study on the association between serum uric acid levels and non-alcoholic fatty liver disease in an elderly population

Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver disorder strongly associated with metabolic dysfunction, particularly in elderly populations where it presents with higher prevalence and severity. This study aimed to investigate the association between serum uric acid (SUA) levels and NAFLD in older adults, focusing on the independent effect of hyperuricemia on NAFLD risk. We enrolled 469 individuals aged ≥ 65 years who underwent community health checkups. The exposure variable was baseline SUA levels, while the outcome variable was the occurrence of NAFLD. Covariates included age, sex, BMI, blood pressure, diabetes status, lipids (TC, TG, LDL, HDL), glycemic indices (FPG, HBA1C), and physical activity. Multivariable logistic regression was applied to estimate the independent effect of SUA levels and hyperuricemia on NAFLD. Hyperuricemia was significantly associated with increased NAFLD risk (adjusted OR 2.16, 95% CI 1.28-3.67). Stratified analysis revealed a stronger association in individuals with elevated triglycerides (TG ≥ 2.26 mmol/L, OR 7.07, 95% CI 1.72-29.18). However, the association between SUA as a continuous variable and NAFLD risk was attenuated after adjusting for metabolic factors. Hyperuricemia independently increases NAFLD risk in older adults, particularly in those with elevated triglycerides, suggesting a potential synergistic effect. These findings highlight the importance of incorporating SUA assessments into routine metabolic evaluations and developing targeted interventions to mitigate NAFLD risk.

Ursolic Acid Ameliorates Alcoholic Liver Injury through Attenuating Oxidative Stress-Mediated Ferroptosis and Modulating Gut Microbiota

Ursolic acid (UA), a triterpenoid found in plants, has many health benefits for liver function. However, understanding how UA intervenes in alcohol-induced ferroptosis remains unclear because of the lack of research. This study explored the protective effects of UA on alcohol-induced liver injury and further elucidated its mechanism of action. Using a mouse model, acute liver injury was induced via high-dose alcohol gavage, and UA's protective effects were assessed by analyzing serum and liver indicators. The results indicated that UA has a significant protective effect against alcohol-induced liver injury in mice. UA significantly decreased serum ALT, AST, TC, and TG levels. Histopathological examination revealed that UA significantly ameliorated liver damage. UA increased ADH, ALDH, and CYP2E1 enzyme expression levels and alleviated alcohol-induced oxidative damage by regulating alcohol metabolism. Moreover, UA increased SOD and GSH-Px levels and lowered the MDA levels in the liver. Furthermore, UA regulated ACC expression by activating the LKB1/AMPK pathway, thereby inhibiting lipid synthesis and peroxidation. UA also upregulated the expression of GPX4 and SLC7A11 in the liver and exerted hepatoprotective effects by inhibiting alcohol-induced ferroptosis. Additionally, 16S rRNA amplicon sequencing showed that excessive alcohol consumption significantly affected the composition of the mouse gut microbiota, with UA intervention proving to be beneficial for improving gut microbiota imbalance. We also validated the protective effects of UA on alcohol-treated HepG2 cells at the cellular level. In summary, these results revealed that UA can alleviate alcoholic liver injury by inhibiting oxidative stress-mediated ferroptosis and regulating gut microbiota. These findings suggest that UA may serve as a functional component in the prevention of alcoholic liver disease.

Royal Jelly Exerts a Potent Anti-Obesity Effect in Rats by Activating Lipolysis and Suppressing Adipogenesis

Background/Objective: This study examined the anti-obesity effect of royal jelly (RJ) in rats fed with a high-fat diet by targeting the major pathways involved in adipogenesis and lipolysis. In addition, it examined whether this effect is AMPK-dependent. Methods: Five groups of adult male albino rats were used (n = 6 each as 1); the control rats were fed with a normal diet (2.9 kcal), and the other groups were as follows: control + RJ (300 mg/kg), HFD (4.75 kcal), HFD + RJ (300 mg/kg), and HFD + RJ (300 mg/kg) + dorsomorphin (an AMPK inhibitor) (0.2 mg/kg). Results: RJ was administered orally to all rats. With no changes in food and energy intake, RJ significantly reduced gains in body weight, fat weight, body mass index (BMI), the Lee index, abdominal circumference (AC), and the adiposity index (AI). It also reduced fasting glucose and insulin levels, HOMA-IR, and the circulatory levels of free fatty acids (FFAs), triglycerides, cholesterol, and LDL-c in the HFD-fed rats. RJ also increased serum glycerol levels and adiponectin levels, but reduced the serum levels of leptin, IL-6, and TNF-α. Moreover, RJ reduced the secretion of IL-6 and TNF-α from isolated WAT. At the tissue level, the HFD + RJ rats exhibited a smaller adipocyte size compared to the HFD rats. At the molecular level, RJ increased the phosphorylation of AMPK, SREBP1, and ACC-1 and increased the mRNA and protein levels of HSL and ATG in the WAT of the HFD rats. In concomitance, RJ increased the mRNA levels of PGC-α1, reduced the protein levels of PPARγ, and repressed the transcriptional activities of PPARγ, SREBP1, and C/EBPαβ in the WAT of these rats. All the aforementioned effects of RJ were prevented by co-treatment with dorsomorphin. Conclusions: RJ exerts a potent anti-obesity effect in rats that is mediated by the AMPk-dependent suppression of WAT adipogenesis and the stimulation of lipolysis.

Bacoside-A repressed the differentiation and lipid accumulation of 3T3-L1 preadipocytes by modulating the expression of adipogenic genes

Obesity is one of the more complicated diseases, it can induce numerous life-threatening diseases mainly diabetes mellitus, cardiovascular disease, hypertension, and certain cancers. In this study, we assessed the efficacy of bacoside-A (a dammarane-type triterpenoid saponin derived from the plant Bacopa monniera Linn.) on the adipogenesis of 3T3-L1 preadipocytes. Results of this study illustrated that bacoside-A decreased the differentiation of 3T3-L1 cell, as evidenced by diminution of lipid droplets, which contains triglycerides and other lipids. During the differentiation process, transcription factors, which are mainly participating in adipogenesis such us CCAAT/enhancer-binding protein α (C/EBPα) and C/EBPβ, peroxisome proliferator-activated receptor-γ (PPARγ), and sterol regulatory element-binding protein-1c (SREBP-1c), expressions were significantly suppressed by bacoside-A. In addition, bacoside-A showed a potent reduction in genes precise to adipocytes such as lipoprotein lipase (LPL), fatty acid synthase (FAS), adipocyte fatty acid-binding protein (FABP4), and leptin expressions. Further, bacoside-A stimulated the phosphorylation of acetyl CoA carboxylase (ACC) and AMP-activated protein kinase (AMPK). These results demonstrated that bacoside-A has anti-adipogenic effects by regulating the transcription factors involved in adipocyte differentiation. Therefore, bacoside-A might be considered as a potent therapeutic agent for alleviating obesity and hyperlipidemia.

AMP-activated protein kinase activation suppresses leptin expression independently of adipogenesis in primary murine adipocytes

Adipogenesis, defined as the development of mature adipocytes from stem cell precursors, is vital for the expansion, turnover and health of adipose tissue. Loss of adipogenic potential in adipose stem cells, or impairment of adipogenesis is now recognised as an underlying cause of adipose tissue dysfunction and is associated with metabolic disease. In this study, we sought to determine the role of AMP-activated protein kinase (AMPK), an evolutionarily conserved master regulator of energy homeostasis, in adipogenesis. Primary murine adipose-derived stem cells were treated with a small molecule AMPK activator (BI-9774) during key phases of adipogenesis, to determine the effect of AMPK activation on adipocyte commitment, maturation and function. To determine the contribution of the repression of lipogenesis by AMPK in these processes, we compared the effect of pharmacological inhibition of acetyl-CoA carboxylase (ACC). We show that AMPK activation inhibits adipogenesis in a time- and concentration-dependent manner. Transient AMPK activation during adipogenic commitment leads to a significant, ACC-independent, repression of adipogenic transcription factor expression. Furthermore, we identify a striking, previously unexplored inhibition of leptin gene expression in response to both short-term and chronic AMPK activation irrespective of adipogenesis. These findings reveal that in addition to its effect on adipogenesis, AMPK activation switches off leptin gene expression in primary mouse adipocytes independently of adipogenesis. Our results identify leptin expression as a novel target of AMPK through mechanisms yet to be identified.

Chinese herbal medicines: The modulator of nonalcoholic fatty liver disease targeting oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Plants are a natural treasure trove; their secondary metabolites participate in several pharmacological processes, making them a crucial component in the synthesis of novel pharmaceuticals and serving as a reserve resource foundation in this process. Nonalcoholic fatty liver disease (NAFLD) is associated with the risk of progression to hepatitis and liver cancer. The "Treatise on Febrile Diseases," "Compendium of Materia Medica," and "Thousand Golden Prescriptions" have listed herbal remedies to treat liver diseases.

AIM OF THE REVIEW

Chinese herbal medicines have been widely used for the prevention and treatment of NAFLD owing to their efficacy and low side effects. The production of reactive oxygen species (ROS) during NAFLD, and the impact and potential mechanism of ROS on the pathogenesis of NAFLD are discussed in this review. Furthermore, common foods and herbs that can be used to prevent NAFLD, as well as the structure-activity relationships and potential mechanisms, are discussed.

METHODS

Web of Science, PubMed, CNKI database, Google Scholar, and WanFang database were searched for natural products that have been used to treat or prevent NAFLD in the past five years. The primary search was performed using the following keywords in different combinations in full articles: NAFLD, herb, natural products, medicine, and ROS. More than 400 research papers and review articles were found and analyzed in this review.

RESULTS

By classifying and discussing the literature, we obtained 86 herbaceous plants, 28 of which were derived from food and 58 from Chinese herbal medicines. The mechanism of NAFLD was proposed through experimental studies on thirteen natural compounds (quercetin, hesperidin, rutin, curcumin, resveratrol, epigallocatechin-3-gallate, salvianolic acid B, paeoniflorin, ginsenoside Rg1, ursolic acid, berberine, honokiol, emodin). The occurrence and progression of NAFLD could be prevented by natural antioxidants through several pathways to prevent ROS accumulation and reduce hepatic cell injuries caused by excessive ROS.

CONCLUSION

This review summarizes the natural products and routinely used herbs (prescription) in the prevention and treatment of NAFLD. Firstly, the mechanisms by which natural products improve NAFLD through antioxidant pathways are elucidated. Secondly, the potential of traditional Chinese medicine theory in improving NAFLD is discussed, highlighting the safety of food-medicine homology and the broader clinical potential of multi-component formulations in improving NAFLD. Aiming to provide theoretical basis for the prevention and treatment of NAFLD.

Qiangjing tablets ameliorate asthenozoospermia via mitochondrial ubiquitination and mitophagy mediated by LKB1/AMPK/ULK1 signaling

CONTEXT

Therapeutic effects of Qiangjing tablets (QJT) on sperm vitality and asthenozoospermia (AZS) have been confirmed. However, the mechanism of action remains unclear.

OBJECTIVE

This study investigates the effects of QJT on AZS and the underlying mechanism of action.

MATERIALS AND METHODS

Sixty Sprague-Dawley rats were randomly divided into six groups: Control, ORN (ornidazole; 200 mg/kg), ORN + QJT-low (0.17 g/mL), ORN + QJT-middle (0.33 g/mL), ORN + QJT-high (0.67 g/mL), and ORN + QJT + Radicicol (0.67 g/mL QJT and 20 mg/kg radicicol) groups. Pathological evaluation and analysis of mitophagy were conducted by H&E staining and transmission electron microscopy, respectively. Reactive oxygen species were detected by flow cytometry. Protein expression was determined by Western blotting.

RESULTS

QJT significantly improved ORN-treated sperm motility and kinematic parameters, as well as the pathological symptoms of testicular and epididymal tissues. In particular, QJT mitigated impaired mitochondrial morphology, and increased the PHB, Beclin-1, LC3-II protein, and ROS levels (p < 0.05), and reduced the protein expression levels of LC3-I and p62 (p < 0.05). Mechanistically, QJT antagonized the downregulation of SCF and Parkin protein levels (p < 0.05). Furthermore, QJT significantly increased the protein expressions levels of LKB1, AMPKα, p-AMPKα, ULK1 and p-ULK1 (p < 0.05). The ameliorative effect of QJT on pathological manifestations, mitochondrial morphology, and the expressions of mitophagy and mitochondrial ubiquitination-related proteins was counteracted by radicicol.

DISCUSSION AND CONCLUSIONS

QJT improved AZS via mitochondrial ubiquitination and mitophagy mediated by the LKB1/AMPK/ULK1 signaling pathway. Our study provides a theoretical basis for the treatment of AZS and male infertility.

Inhibitory Effect of Isopanduratin A on Adipogenesis: A Study of Possible Mechanisms

The root of Boesenbergia rotunda, a culinary plant commonly known as fingerroot, has previously been reported to possess anti-obesity activity, with four flavonoids identified as active principles, including pinostrobin, panduratin A, cardamonin, and isopanduratin A. However, the molecular mechanisms underlying the antiadipogenic potential of isopanduratin A remain unknown. In this study, isopanduratin A at non-cytotoxic concentrations (1-10 μM) significantly suppressed lipid accumulation in murine (3T3-L1) and human (PCS-210-010) adipocytes in a dose-dependent manner. Downregulation of adipogenic effectors (FAS, PLIN1, LPL, and adiponectin) and adipogenic transcription factors (SREBP-1c, PPARγ, and C/EBPα) occurred in differentiated 3T3-L1 cells treated with varying concentrations of isopanduratin A. The compound deactivated the upstream regulatory signals of AKT/GSK3β and MAPKs (ERK, JNK, and p38) but stimulated the AMPK-ACC pathway. The inhibitory trend of isopanduratin A was also observed with the proliferation of 3T3-L1 cells. The compound also paused the passage of 3T3-L1 cells by inducing cell cycle arrest at the G0/G1 phase, supported by altered levels of cyclins D1 and D3 and CDK2. Impaired p-ERK/ERK signaling might be responsible for the delay in mitotic clonal expansion. These findings revealed that isopanduratin A is a strong adipogenic suppressor with multi-target mechanisms and contributes significantly to anti-obesogenic activity. These results suggest the potential of fingerroot as a functional food for weight control and obesity prevention.

Prospecting in silico antibacterial activity of a peptide from trypsin inhibitor isolated from tamarind seed

Bacterial infections have become a global concern, stimulating the growing demand for natural and biologically safe therapeutic agents with antibacterial action. This study was evaluated the genotoxicity of the trypsin inhibitor isolated from tamarind seeds (TTI) and the antibacterial effect of TTI theoric model, number 56, and conformation number 287 (TTIp 56/287) and derived peptides in silico. TTI (0.3 and 0.6 mg.mL⁻¹) did not cause genotoxicity in cells (p > 0.05). In silico, a greater interaction of TTIp 56/287 with the Gram-positive membrane (GP) was observed, with an interaction potential energy (IPE) of −1094.97 kcal.mol⁻¹. In the TTIp 56/287-GP interaction, the Arginine, Threonine (Thr), and Lysine residues presented lower IPE. In molecular dynamics (MD), Peptidotrychyme59 (TVSQTPIDIPIGLPVR) showed an IPE of −518.08 kcal.mol⁻¹ with the membrane of GP bacteria, and the Thr and Arginine residues showed the greater IPE. The results highlight new perspectives on TTI and its derived peptides antibacterial activity.

Effects of Chrysoeriol on Adipogenesis and Lipolysis in 3T3-L1 Adipocytes

We examined the effect of chrysoeriol on adipogenesis and lipolysis and elucidated the underlying molecular mechanisms. Chrysoeriol inhibited fat deposition in adipocytes. Treatment with chrysoeriol suppressed the expression of peroxisome proliferator-activated receptor γ, fatty acid synthase, fatty acid-binding protein, CCAAT/enhancer-binding proteins (C/EBP) α, C/EBPβ, and sterol regulatory element-binding protein-1. In addition, chrysoeriol significantly elevated the activation of 5'-adenosine monophosphate-activated protein kinase. Moreover, chrysoeriol increased free glycerol and fatty acid levels and promoted lipolysis in adipocytes. Overexpression of adipose triglyceride lipase and hormone-sensitive lipase by chrysoeriol led to increased lipolysis in 3T3-L1 adipocytes. Taken together, chrysoeriol showed anti-adipogenic and lipolytic properties in adipocytes.

Protective mechanisms of loquat leaf extract and ursolic acid against diabetic pro-inflammation

The pharmacological effectiveness of loquat leaf extract (LE) and its important component, ursolic acid (UA), in the treatment of diabetes mellitus, has been well established in traditional medicine; however, the mechanism underlying their action is still unclear. We evaluated the protective effects of LE and UA against hyperglycemia-induced advanced glycation end product (AGE) formations and hepatic pro-inflammation. Oral administration of UA and LE at a dose of 50 mg/kg/day for 15 days yielded no significant hypoglycemic effect in diabetic db/db mice. UA and LE suppressed hepatic oxidative stress and AGE formation in diabetic mice, and this was followed by the downregulated mitogen-activated protein kinase signaling and nuclear factor κ B (NF-κB) activity. To identify the molecular target of LE and UA, a docking simulation was performed, and this predicted UA to bind to liver kinase B1 (LKB1), an upstream of AMP-activated protein kinase (AMPK)/transcription factor forkhead box O3 (FOXO3) axis. UA reversed the high-glucose-induced downregulation of LKB1-AMPK1-FOXO3 activation and antioxidant gene transcription. These findings demonstrated the antioxidant and anti-inflammatory effects of UA and LE against hyperglycemia-induced hepatic inflammation. Furthermore, we speculate that the LKB1/AMPK/FOXO3 pathway is a potential target responsible for these beneficial effects of LE and UA.

Natural products: Potential therapeutic agents to prevent skeletal muscle atrophy

The skeletal muscle (SkM) is the largest organ, which plays a vital role in controlling musculature, locomotion, body heat regulation, physical strength, and metabolism of the body. A sedentary lifestyle, aging, cachexia, denervation, immobilization, etc. Can lead to an imbalance between protein synthesis and degradation, which is further responsible for SkM atrophy (SmA). To date, the understanding of the mechanism of SkM mass loss is limited which also restricted the number of drugs to treat SmA. Thus, there is an urgent need to develop novel approaches to regulate muscle homeostasis. Presently, some natural products attained immense attraction to regulate SkM homeostasis. The natural products, i.e., polyphenols (resveratrol, curcumin), terpenoids (ursolic acid, tanshinone IIA, celastrol), flavonoids, alkaloids (tomatidine, magnoflorine), vitamin D, etc. exhibit strong potential against SmA. Some of these natural products have been reported to have equivalent potential to standard treatments to prevent body lean mass loss. Indeed, owing to the large complexity, diversity, and slow absorption rate of bioactive compounds made their usage quite challenging. Moreover, the use of natural products is controversial due to their partially known or elusive mechanism of action. Therefore, the present review summarizes various experimental and clinical evidence of some important bioactive compounds that shall help in the development of novel strategies to counteract SmA elicited by various causes.

Sinapic acid prevents adipogenesis by regulating transcription factors and exerts an anti-ROS effect by modifying the intracellular anti-oxidant system in 3T3-L1 adipocytes

Objectives

In this study, we tested the hypothesis that sinapic acid (SA), a naturally occurring hydroxycinnamic acid found in vegetables, cereal grains, and oilseed crops with various biological activities suppresses adipogenesis in 3T3-L1 adipocytes by down-regulating adipogenesis transcription factor.

Materials and Methods

3T3-L1 adipocytes were treated with SA and evaluated by Oil Red O staining, triglyceride estimation, lipolysis, and reverse transcription-polymerase chain reaction. 3T3-L1 adipocytes were treated with various concentrations of SA (100 to 1000 μmol) during differentiation.

Results

SA prevented an increase in adipocytes by reducing preadipocyte clonal expansion. ORO staining analyses revealed that SA reduced cytoplasmic lipid droplet accumulation in 3T3-L1 by 57% at the highest concentration of 1000 μmol without affecting cell viability. Furthermore, SA down-regulated the expression of peroxisome proliferator-activated receptor-gamma, CCAAT/enhancer-binding protein alpha, sterol regulatory element-binding protein 1c, and fatty acid synthase. ROS generated during adipogenesis was also attenuated by SA treatment by increasing antioxidant enzymes superoxide dismutase, catalase, and the cellular antioxidant glutathione. SA demonstrated no in vivo toxicity in the Drosophila melanogaster model.

Conclusion

These results suggest that SA exerts anti-oxidant and anti-adipogenic effects and could be used as a functional nutraceutical ingredient in combatting obesity-related diseases.

Ethyl Gallate Dual-Targeting PTPN6 and PPARγ Shows Anti-Diabetic and Anti-Obese Effects

The emergence of the high correlation between type 2 diabetes and obesity with complicated conditions has led to the coinage of the term “diabesity”. AMP-activated protein kinase (AMPK) activators and peroxisome proliferator-activated receptor (PPARγ) antagonists have shown therapeutic activity for diabesity, respectively. Hence, the discovery of compounds that activate AMPK as well as antagonize PPARγ may lead to the discovery of novel therapeutic agents for diabesity. In this study, the knockdown of PTPN6 activated AMPK and suppressed adipogenesis in 3T3-L1 cells. By screening a library of 1033 natural products against PTPN6, we found ethyl gallate to be the most selective inhibitor of PTPN6 (K_i = 3.4 μM). Subsequent assay identified ethyl gallate as the best PPARγ antagonist (IC₅₀ = 5.4 μM) among the hit compounds inhibiting PTPN6. Ethyl gallate upregulated glucose uptake and downregulated adipogenesis in 3T3-L1 cells as anticipated. These results strongly suggest that ethyl gallate, which targets both PTPN6 and PPARγ, is a potent therapeutic candidate to combat diabesity.

Effect of Anti-Obesity and Antioxidant Activity through the Additional Consumption of Peel from ‘Fuji’ Pre-Washed Apple

There is limited information on the health effects of apple peel taken from ‘Fuji’ (Malus pumila Mill) apples washed with ozonated water. To clarify the health-promoting effects of peel, the triterpenoids (ursolic acid and oleanolic acid) were quantified with gas chromatograph–mass spectrometry. Anti-obesity effects of apple peel extract on the 3T3-L1 pre-adipocyte cell were compared with apple flesh, whole apple, and ursolic acid. The peel extract treatment with 3.30 ± 1.05 μM of ursolic acid significantly suppressed (p < 0.05) the lipid accumulation compared with the content in flesh, and a similar level was reached in the 5 μM ursolic acid positive control group. In the peel extract and ursolic acid treatment groups, the C16:0 concentration was significantly inhibited (p < 0.05), implying the anti-obesity effect of ursolic acid on the 3T3-L1 cell. Moreover, apple peel contributed 41% of the total flavonoids content and 31% of the phenolic contents of the whole apple, but only accounted for less than 10% of the whole apple (weight basis). This study’s results offer basic data on pre-washed apple as a health functional food, offering information about the health benefits of apple peel, calculated based on the partial ratio in the whole apple.

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.

Saikosaponin A and D Inhibit Adipogenesis via the AMPK and MAPK Signaling Pathways in 3T3-L1 Adipocytes

Obesity is a lipid metabolism disorder caused by genetic, medicinal, nutritional, and other environmental factors. It is characterized by a complex condition of excess lipid accumulation in adipocytes. Adipogenesis is a differentiation process that converts preadipocytes into mature adipocytes and contributes to excessive fat deposition. Saikosaponin A (SSA) and saikosaponin D (SSD) are triterpenoid saponins separated from the root of the Bupleurum chinensis, which has long been used to treat inflammation, fever, and liver diseases. However, the effects of these constituents on lipid accumulation and obesity are poorly understood. We investigated the anti-obesity effects of SSA and SSD in mouse 3T3-L1 adipocytes. The MTT assay was performed to measure cell viability, and Oil Red O staining was conducted to determine lipid accumulation. Various adipogenic transcription factors were evaluated at the protein and mRNA levels by Western blot assay and quantitative reverse transcription polymerase chain reaction (qRT-PCR). Here, we showed that SSA and SSD significantly inhibited lipid accumulation without affecting cell viability within the range of the tested concentrations (0.938–15 µM). SSA and SSD also dose-dependently suppressed the expression of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), sterol regulatory element binding protein-1c (SREBP-1c), and adiponectin. Furthermore, the decrease of these transcriptional factors resulted in the repressed expression of several lipogenic genes including fatty acid binding protein (FABP4), fatty acid synthase (FAS), and lipoprotein lipase (LPL). In addition, SSA and SSD enhanced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its substrate, acetyl-CoA carboxylase (ACC), and inhibited the phosphorylation of extracellular-regulated kinase 1/2 (ERK1/2) and p38, but not c-Jun-N-terminal kinase (JNK). These results suggest that SSA and SSD inhibit adipogenesis through the AMPK or mitogen-activated protein kinase (MAPK) pathways in the early stages of adipocyte differentiation. This is the first study on the anti-adipogenic effects of SSA and SSD, and further research in animals and humans is necessary to confirm the potential of saikosaponins as therapeutic agents for obesity.

Ursolic Acid and Related Analogues: Triterpenoids with Broad Health Benefits

Ursolic acid (UA) is a well-studied natural pentacyclic triterpenoid found in herbs, fruit and a number of traditional Chinese medicinal plants. UA has a broad range of biological activities and numerous potential health benefits. In this review, we summarize the current data on the bioavailability and pharmacokinetics of UA and review the literature on the biological activities of UA and its closest analogues in the context of inflammation, metabolic diseases, including liver and kidney diseases, obesity and diabetes, cardiovascular diseases, cancer, and neurological disorders. We end with a brief overview of UA’s main analogues with a special focus on a newly discovered naturally occurring analogue with intriguing biological properties and potential health benefits, 23-hydroxy ursolic acid.

Ursolic acid induces white adipose tissue beiging in high-fat-diet obese male mice

Ursolic acid (UA) shows an effect on obesity and related metabolic diseases, but its mechanism of action remains unclear. We found that UA clearly reduced the body weight and adipose tissue mass and improved the glucose tolerance and insulin sensitivity in obese male mice. UA treatment significantly reduced the volume and weights of the epididymal white adipose tissue (eWAT) and inguinal subcutaneous white adipose tissue (igSWAT) of HFD-fed mice, respectively. UA also decreased the expression of genes involved in adipocyte differentiation and lipogenesis in igSWAT. Real-time PCR and immunohistochemistry showed that the expression of beiging-related genes 4-1BB factor (CD137), T-box transcription factor 1 (TBX1), and transmembrane protein 26 (TMEM26) were significantly increased in the UA treatment group. UA treatment significantly reduced the weight of gastrocnemius muscle (GM) and lipid droplets in the GM. UA treatment significantly upregulated the expression of PR domain-containing 16 (PRDM16), peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), and fibronectin type 3 domain-containing protein 5 (FNDC5) in GM and igSWAT. UA also stimulated irisin secretion in the serum. In conclusion, these results indicate that UA plays an anti-obesogenic role by increasing the secretion of irisin and promoting the beiging of WAT.

Effects of Bacillus Subtilis-Fermented White Sword Bean Extract on Adipogenesis and Lipolysis of 3T3-L1 Adipocytes

To investigate the adipogenesis and lipolysis effects of the Bacillus subtilis-fermented white sword bean extract (FWSBE) on 3T3-L1 adipocytes, we treated 3T3-L1 preadipocytes before and after differentiation with FWSBE and measured triglyceride, free glycerol, mRNA, and protein levels. First, FWSBE reduced the cell viability of 3T3-L1 pre-adipocytes under 1000 µg/mL conditions. Triglyceride accumulation in 3T3-L1 pre-adipocytes was suppressed, and free glycerol content in mature 3T3-L1 adipocytes was increased in the FWSBE treatment groups, indicating that FWSBE has anti-obesity effects. Further, FWSBE suppressed adipogenesis in 3T3-L1 pre-adipocytes by lowering the protein levels of C/EBPα, PPARγ, and FAS and increasing the level of pACC and pAMPK. Additionally, FWSBE promoted lipolysis in mature 3T3-L1 adipocytes by increasing the transcription levels of Ppara, Acox, and Lcad and the protein levels of pHSL and ATGL. Thus, we suggest that FWSBE can be a potential dietary supplement because of its anti-obesity properties.

Carnosic Acid Attenuates an Early Increase in ROS Levels during Adipocyte Differentiation by Suppressing Translation of Nox4 and Inducing Translation of Antioxidant Enzymes

The objective of this study was to investigate molecular mechanisms underlying the ability of carnosic acid to attenuate an early increase in reactive oxygen species (ROS) levels during MDI-induced adipocyte differentiation. The levels of superoxide anion and ROS were determined using dihydroethidium (DHE) and 2′-7′-dichlorofluorescin diacetate (DCFH-DA), respectively. Both superoxide anion and ROS levels peaked on the second day of differentiation. They were suppressed by carnosic acid. Carnosic acid attenuates the translation of NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 4 (Nox4), p47^phox, and p22^phox, and the phosphorylation of nuclear factor-kappa B (NF-κB) and NF-κB inhibitor (IkBa). The translocation of NF-κB into the nucleus was also decreased by carnosic acid. In addition, carnosic acid increased the translation of heme oxygenase-1 (HO-1), γ–glutamylcysteine synthetase (γ-GCSc), and glutathione S-transferase (GST) and both the translation and nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2). Taken together, these results indicate that carnosic acid could down-regulate ROS level in an early stage of MPI-induced adipocyte differentiation by attenuating ROS generation through suppression of NF-κB-mediated translation of Nox4 enzyme and increasing ROS neutralization through induction of Nrf2-mediated translation of phase II antioxidant enzymes such as HO-1, γ-GCS, and GST, leading to its anti-adipogenetic effect.

Ursolic Acid Lactone Obtained from Eucalyptus tereticornis Increases Glucose Uptake and Reduces Inflammatory Activity and Intracellular Neutral Fat: An In Vitro Study

Obesity has a strong relationship to insulin resistance and diabetes mellitus, a chronic metabolic disease that alters many physiological functions. Naturally derived drugs have aroused great interest in treating obesity, and triterpenoids are natural compounds with multiple biological activities and antidiabetic mechanisms. Here, we evaluated the bioactivity of ursolic acid lactone (UAL), a lesser-known triterpenoid, obtained from Eucalyptus tereticornis. We used different cell lines to show for the first time that this molecule exhibits anti-inflammatory properties in a macrophage model, increases glucose uptake in insulin-resistant muscle cells, and reduces triglyceride content in hepatocytes and adipocytes. In 3T3-L1 adipocytes, UAL inhibited the expression of genes involved in adipogenesis and lipogenesis, enhanced the expression of genes involved in fat oxidation, and increased AMP-activated protein kinase phosphorylation. The range of biological activities demonstrated in vitro indicates that UAL is a promising molecule for fighting diabetes.

Direct Conversion of Human Fibroblasts into Adipocytes Using a Novel Small Molecular Compound: Implications for Regenerative Therapy for Adipose Tissue Defects

There is a need in plastic surgery to prepare autologous adipocytes that can be transplanted in patients to reconstruct soft tissue defects caused by tumor resection, including breast cancer, and by trauma and other diseases. Direct conversion of somatic cells into adipocytes may allow sufficient functional adipocytes to be obtained for use in regeneration therapy. Chemical libraries of 10,800 molecules were screened for the ability to induce lipid accumulation in human dermal fibroblasts (HDFs) in culture. Chemical compound-mediated directly converted adipocytes (CCCAs) were characterized by lipid staining, immunostaining, and qRT-PCR, and were also tested for adipokine secretion and glucose uptake. CCCAs were also implanted into mice to examine their distribution in vivo. STK287794 was identified as a small molecule that induced the accumulation of lipid droplets in HDFs. CCCAs expressed adipocyte-related genes, secreted adiponectin and leptin, and abundantly incorporated glucose. After implantation in mice, CCCAs resided in granulation tissue and remained adipose-like. HDFs were successfully converted into adipocytes by adding a single chemical compound, STK287794. C/EBPα and PPARγ were upregulated in STK287794-treated cells, which strongly suggests involvement of these adipocyte-related transcription factors in the chemical direct conversion. Our method may be useful for the preparation of autogenous adipocytes for transplantation therapy for soft tissue defects and fat tissue atrophy.

Molecular mechanism underlying the hypolipidemic effect of Shanmei Capsule based on network pharmacology and molecular docking

BACKGROUND:

Shanmei Capsule is a famous preparation in China. However, the related mechanism of Shanmei Capsule against hyperlipidemia has yet to be revealed.

OBJECTIVE:

To elucidate underlying mechanism of Shanmei Capsule against hyperlipidemia through network pharmacology approach and molecular docking.

METHODS:

Active ingredients, targets of Shanmei Capsule as well as targets for hyperlipidemia were screened based on database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were performed via Database for Annotation, Visualization, and Integrated Discovery (DAVID) 6.8 database. Ingredient-target-disease-pathway network was visualized utilizing Cytoscape software and molecular docking was performed by Autodock Vina.

RESULTS:

Seventeen active ingredients in Shanmei Capsule were screened out with a closely connection with 34 hyperlipidemia-related targets. GO analysis revealed 40 biological processes, 5 cellular components and 29 molecular functions. A total of 15 signal pathways were enriched by KEGG pathway enrichment analysis. The docking results indicated that the binding activities of key ingredients for PPAR-α are equivalent to that of the positive drug lifibrate.

CONCLUSIONS:

The possible molecular mechanism mainly involved PPAR signaling pathway, Bile secretion and TNF signaling pathway via acting on MAPK8, PPARγ, MMP9, PPARα, FABP4 and NOS2 targets.

Pomolic acid in persimmon peel suppresses the increase in glycerol-3 phosphate dehydrogenase activity in 3T3-L1 adipocytes

Persimmon peels, though usually discarded, are useful sources of nutraceuticals. In this study, persimmon peel-derived pomolic acid was found to suppress the increase in the activity of glycerol-3 phosphate dehydrogenase, a neutral fat synthesis-related enzyme, in 3T3-L1 adipocytes, whereas oleanolic and ursolic acids did not exert this effect. Therefore, persimmon peel may be an effective functional food material.

Molecular mechanism of down-regulating adipogenic transcription factors in 3T3-L1 adipocyte cells by bioactive anti-adipogenic compounds

Obesity is growing at an alarming rate, which is characterized by increased adipose tissue. It increases the probability of many health complications, such as diabetes, arthritis, cardiac disease, and cancer. In modern society, with a growing population of obese patients, several individuals have increased insulin resistance. Herbal medicines are known as the oldest method of health care treatment for obesity-related secondary health issues. Several traditional medicinal plants and their effective phytoconstituents have shown anti-diabetic and anti-adipogenic activity. Adipose tissue is a major site for lipid accumulation as well as the whole-body insulin sensitivity region. 3T3-L1 cell line model can achieve adipogenesis. Adipocyte characteristics features such as expression of adipocyte markers and aggregation of lipids are chemically induced in the 3T3-L1 fibroblast cell line. Differentiation of 3T3-L1 is an efficient and convenient way to obtain adipocyte like cells in experimental studies. Peroxisome proliferation activated receptor γ (PPARγ) and Cytosine-Cytosine-Adenosine-Adenosine-Thymidine/Enhancer-binding protein α (CCAAT/Enhancer-binding protein α or C/EBPα) are considered to be regulating adipogenesis at the early stage, while adiponectin and fatty acid synthase (FAS) is responsible for the mature adipocyte formation. Excess accumulation of these adipose tissues and lipids leads to obesity. Thus, investigating adipose tissue development and the underlying molecular mechanism is important in the therapeutical approach. This review describes the cellular mechanism of 3T3-L1 fibroblast cells on potential anti-adipogenic herbal bioactive compounds.

Roflumilast Suppresses Adipogenic Differentiation via AMPK Mediated Pathway

Obesity and related disorders have increasingly become global health problems over the years. In recent years, obesity has been recognized as the most important risk factor for a variety of diseases including cardiovascular diseases, type 2 diabetes, steatohepatitis, and cancer. The medical anti-obesity treatment is to intervene in the metabolic process of adipocytes by suppressing adipogenesis and promoting lipolysis. The Phosphodiesterase-4 (PDE4) pathway is involved in fat mass control and metabolic regulation. The present study aimed to investigate the effects of Roflumilast, a selective PDE4 inhibitor, on the differentiation of 3T3-L1 cells and the high fat diet-induced obesity in mice. We showed that treatment with Roflumilast inhibited lipid accumulation and triglycerides storage in mature 3T3-L1 cells, suggesting that Roflumilast suppressed adipogenesis. Mechanistically, we found that Roflumilast decreased the differentiation-induced expression of the adipogenesis genes including SREBP1C, FABP4, and Glut4, as well as their regulators including PPAR-γ and C/EBPα. Moreover, we proved that the effect of Roflumilast was dependent on the activation of the metabolic regulator AMPKα. The treatment with Roflumilast remarkably decreased the animals' body weight, visceral adipose tissue weight, and adipocyte size in high fat diet-induced obese mice. In conclusion, our study revealed that Roflumilast suppressed adipogenesis and promoted lipolysis in cell culture and mice models via AMPK-mediated inhibition of PPAR-γ and C/EBPα. These findings imply roflumilast could have therapeutic potential in obesity-related diseases.

Morolic Acid 3-O-Caffeate Inhibits Adipogenesis by Regulating Epigenetic Gene Expression

Obesity causes a wide range of metabolic diseases including diabetes, cardiovascular disease, and kidney disease. Thus, plenty of studies have attempted to discover naturally derived compounds displaying anti-obesity effects. In this study, we evaluated the inhibitory effects of morolic acid 3-O-caffeate (MAOC), extracted from Betula schmidtii, on adipogenesis. Treatment of 3T3-L1 cells with MAOC during adipogenesis significantly reduced lipid accumulation and decreased the expression of adiponectin, a marker of mature adipocytes. Moreover, the treatment with MAOC only during the early phase (day 0-2) sufficiently inhibited adipogenesis, comparable with the inhibitory effects observed following MAOC treatment during the whole processes of adipogenesis. In the early phase of adipogenesis, the expression level of Wnt6, which inhibits adipogenesis, increased by MAOC treatment in 3T3-L1 cells. To identify the gene regulatory mechanism, we assessed alterations in histone modifications upon MAOC treatment. Both global and local levels on the Wnt6 promoter region of histone H3 lysine 4 trimethylation, an active transcriptional histone marker, increased markedly by MAOC treatment in 3T3-L1 cells. Our findings identified an epigenetic event associated with inhibition of adipocyte generation by MAOC, suggesting its potential as an efficient therapeutic compound to cure obesity and metabolic diseases.

Effect of Age and Lipoperoxidation in Rat and Human Adipose Tissue-Derived Stem Cells

A wide range of clinical applications in regenerative medicine were opened decades ago with the discovery of adult stem cells. Highly promising adult stem cells are mesenchymal stem/stromal cells derived from adipose tissue (ADSCs), primarily because of their abundance and accessibility. These cells have multipotent properties and have been used extensively to carry out autologous transplants. However, the biology of these cells is not entirely understood. Among other factors, the regeneration capacity of these cells will depend on both their capacity of proliferation/differentiation and the robustness of the biochemical pathways that allow them to survive under adverse conditions like those found in damaged tissues. The transcription factors, such as Nanog and Sox2, have been described as playing an important role in stem cell proliferation and differentiation. Also, the so-called longevity pathways, in which AMPK and SIRT1 proteins play a crucial role, are essential for cell homeostasis under stressful situations. These pathways act by inhibiting the translation through downregulation of elongation factor-2 (eEF2). In order to deepen knowledge of mesenchymal stem cell biology and which factors are determinant in the final therapeutic output, we evaluate in the present study the levels of all of these proteins in the ADSCs from humans and rats and how these levels are affected by aging and the oxidative environment. Due to the effect of aging and oxidative stress, our results suggest that before performing a cell therapy with ADSCs, several aspects reported in this study such as oxidative stress status and proliferation and differentiation capacity should be assessed on these cells. This would allow us to know the robustness of the transplanted cells and to predict the therapeutic result, especially in elder patients, where probably ADSCs do not carry out their biological functions in an optimal way.

Ursolic acid induces the production of IL6 and chemokines in both adipocytes and adipose tissue

Adipose tissue inflammation plays an important role in the regulation of glucose and lipids metabolism. It is unknown whether Ursolic acid (UA) could regulate adipose tissue inflammation, though it can regulate inflammation in many other tissues. In this study, 3T3-L1 adipocytes, DIO mice and lean mice were treated with UA or vehicle. Gene expression of inflammatory factors, chemokines and immune markers in adipocytes and adipose tissue, cytokines in cell culture medium and serum, and inflammation regulatory pathways in adipocytes were detected. Results showed that UA increased the expression of interleukins and chemokines, but not TNFα, in both adipocytes and adipose tissue. IL6 and MCP1 levels in the cell culture medium and mouse serum were induced by UA treatment. Cd14 expression level and number of CD14+ monocytes were higher in UA treated adipose tissue than those in the control group. Glucose tolerance test was impaired by UA treatment in DIO mice. Mechanistically, UA induced the expression of Tlr4 and the phosphorylation levels of ERK and NFκB in adipocytes. In conclusion, our study indicated that short-term UA administration could induce CD14+ monocytes infiltration by increasing the production of interleukins and chemokines in mouse adipose tissue, which might further impair glucose tolerance test.

Vanadium-protein complex inhibits human adipocyte differentiation through the activation of β-catenin and LKB1/AMPK signaling pathway

Obesity is a common disease over the world and is tightly associated with diabetes mellitus, cardiovascular and cancer disease. Although our previous study showed that the synthetic vanadium-protein (V-P) complex had a better effect on antioxidant and antidiabetic, the relative molecular mechanisms are still entirely unknown. Hence, we investigated the effect of the synthetic V-P complex on adipocyte differentiation (adipogenesis) using human preadipocytes to clarify its molecular mechanisms of action. The primary human preadipocytes were cultured with and without V-P complex during adipocyte differentiation. The cell proliferation, lipid accumulation, and the protein expression of transcription factors and related enzymes were determined for the differentiated human preadipocytes. In this study, the 20 μg/mL of V-P complex reduced the lipid and triglyceride (TG) content by 74.47 and 57.39% (p < 0.05), respectively, and down-regulated the protein expressions of peroxisome proliferator-activated receptor-γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), sterol regulatory element-binding protein 1 (SREBP-1) and fatty acid synthase (FAS). Additionally, the V-P complex significantly up-regulated the protein levels of total β-catenin (t-β-catenin), nuclear β-catenin (n-β-catenin), phosphorylated adenosine monophosphate-activated protein kinase alpha (p-AMPKα) and liver kinase B1 (p-LKB1). These showed that the inhibitory effect of V-P complex on human adipogenesis was mediated by activating Wnt/β-catenin and LKB1/AMPK-dependent signaling pathway. Therefore, the synthetic V-P complex could be considered as a candidate for prevention and treatment of obesity.

48Biochemical mechanisms of the anti-obesity effect of a triterpenoid-enriched extract of Cynomorium songaricum in mice with high-fat-diet-induced obesity

BACKGROUND

HCY2, a triterpenoid-enriched extract of Cynomorii Herba, has been shown to reduce body weight and adiposity and attenuate manifestations of the associated metabolic syndrome in high-fat-diet (HFD)-fed mice.

PURPOSE

The current study aimed to investigate the biochemical mechanism underlying the anti-obesity effect produced by HCY2.

STUDY DESIGN

An HCY2-containing extract was examined for its effects on the regulation of adenosine monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor gamma co-activator-1 (PGC1) pathways and the protein expression related to mitochondrial uncoupling and biogenesis in skeletal muscle using an HFD-induced obese mouse model.

METHODS

The obese mouse model was produced by providing HFD (60% kcal from fat) ad libitum. The effects and signaling mechanisms of HCY2 were examined using analytical procedures which included enzyme-linked immunosorbent assay kits, Western blot analysis, and the use of a Clark-type oxygen electrode.

RESULTS

The current study revealed that the weight reduction produced by HCY2 is associated with the activation of the AMPK signaling pathway, with resultant increases in mitochondrial biogenesis and expression of uncoupling protein 3 in skeletal muscle in vivo. The use of a recoupler, ketocholestanol, delineated the precise role of mitochondrial uncoupling in the anti-obesity effect afforded by HCY2 in obese mice.

CONCLUSION

Our experimental findings offer a promising prospect for the use of HCY2 in the management of obesity through the regulation of AMPK/PGC1 pathways.

Molecular Mechanisms of Adipogenesis: The Anti-adipogenic Role of AMP-Activated Protein Kinase

Obesity is now a widespread disorder, and its prevalence has become a critical concern worldwide, due to its association with common co-morbidities like cancer, cardiovascular diseases and diabetes. Adipose tissue is an endocrine organ and therefore plays a critical role in the survival of an individual, but its dysfunction or excess is directly linked to obesity. The journey from multipotent mesenchymal stem cells to the formation of mature adipocytes is a well-orchestrated program which requires the expression of several genes, their transcriptional factors, and signaling intermediates from numerous pathways. Understanding all the intricacies of adipogenesis is vital if we are to counter the current epidemic of obesity because the limited understanding of these intricacies is the main barrier to the development of potent therapeutic strategies against obesity. In particular, AMP-Activated Protein Kinase (AMPK) plays a crucial role in regulating adipogenesis – it is arguably the central cellular energy regulation protein of the body. Since AMPK promotes the development of brown adipose tissue over that of white adipose tissue, special attention has been given to its role in adipose tissue development in recent years. In this review, we describe the molecular mechanisms involved in adipogenesis, the role of signaling pathways and the substantial role of activated AMPK in the inhibition of adiposity, concluding with observations which will support the development of novel chemotherapies against obesity epidemics.

High hydrostatic pressure extract of Siegesbeckia orientalis inhibits adipogenesis through the activation of the Wnt/β-catenin signaling pathway

St. Paul's Wort (Siegesbeckia orientalis L.) confers anti-oxidative, anti-inflammatory, anti-allergic, anti-infertility, and immunosuppressive properties. Here, we elucidated whether high hydrostatic pressure extract of St. Paul's Wort (SPW-HHPE) had anti-adipogenic activity. SPW-HHPE inhibited adipogenesis by reducing intracellular lipid accumulation. SPW-HHPE reduced the mRNA and protein expression of adipogenic regulatory factors [peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein alpha (C/EBPα), and sterol regulatory element binding protein-1c]. In addition, SPW-HHPE decreased the mRNA expression levels of lipogenic enzymes (fatty acid synthase and acetyl-CoA carboxylase) as well as adipocytokines (adiponectin and leptin). The inhibitory effect of SPW-HHPE on adipogenesis was mainly attributed to the enhancement of the Wnt/β-catenin signaling pathway. When β-catenin siRNA was transfected into 3T3-L1 adipocytes, the mRNA expression of PPARγ and C/EBPα was upregulated; however, their expression was attenuated by SPW-HHPE. These results suggest that SPW-HHPE suppresses adipogenesis by stimulating Wnt/β-catenin pathway.

Effect of Ursolic Acid on Insulin Resistance and Hyperinsulinemia in Rats with Diet-Induced Obesity: Role of Adipokines Expression

Excess of visceral adipose tissue (VAT) characteristic of obesity leads to a proinflammatory state disrupting the insulin signaling pathway, triggering insulin resistance (IR) and inflammation, the main processes contributing to obesity comorbidities. Ursolic acid (UA), a pentacyclic triterpenoid occurring in a variety of plant foods, exhibits anti-inflammatory properties. The aim of this study was to evaluate UA effects on IR, hyperinsulinemia, and inflammation in experimental diet-induced obesity. Forty male Wistar rats were randomly assigned to eight groups (n = 5). One group was used for time 0. Three groups were labeled as OBE (control): receiving high-fat diet (HFD; fat content 45.24% of energy) during 3, 6, or 9 weeks; three groups UA-PREV: exposed to simultaneous HFD and UA during 3, 6, or 9 weeks to evaluate UA preventive effects; one group UA-REV: receiving HFD for 6 weeks, followed by simultaneous HFD and UA for three additional weeks to analyze UA reversal effects. Measurements were performed after 3, 6, or 9 weeks of treatment. Adiposity was calculated by weighing VAT after sacrifice. Serum markers were quantified through colorimetric and enzyme-linked immunosorbent assay methods. VAT adipokines RNAm expression was evaluated by quantitative reverse transcriptase-polymerase chain reaction. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. UA significantly decreased adiposity, IR, hyperinsulinemia, triacylglycerides, and cholesterol levels, and also VAT mRNA expression of MCP-1 (monocyte chemoattractant protein-1), IL (interleukin)-1β and IL-6, concomitantly increasing adiponectin levels. UA metabolic effects demonstrated in this study support its potential therapeutic utility to improve IR, hyperinsulinemia, and inflammation observed in obesity and diabetes.

Liver Kinase B1 Fine-Tunes Lineage Commitment of Human Fetal Synovium-Derived Stem Cells

Liver kinase B1 (LKB1), a serine/threonine protein, is a key regulator in stem cell function and energy metabolism. Herein, we describe the role of LKB1 in modulating the differentiation of synovium-derived stem cells (SDSCs) toward chondrogenic, adipogenic, and osteogenic lineages. Human fetal SDSCs were transduced with CRISPR associated protein 9 (Cas9)-single-guide RNA vectors to knockout or lentiviral vectors to overexpress the LKB1 gene. Analyses including ICE (Inference of CRISPR Edits) data from Sanger sequencing and quantitative polymerase chain reaction (qPCR) as well as Western blot demonstrated successful knockout (KO) or overexpression (OE) of LKB1 in human fetal SDSCs without any detectable side effects in morphology, proliferation rate, and cell cycle. LKB1 KO increased CD146 expression; interestingly, LKB1 OE increased SSEA4 level. The qPCR data showed that LKB1 KO upregulated the levels of SOX2 and NANOG while LKB1 OE lowered the expression of POU5F1 and KLF4. Furthermore, LKB1 KO enhanced, and LKB1 OE inhibited, chondrogenic and adipogenic differentiation potential. However, perhaps due to the inherent inability to achieve osteogenesis, LKB1 did not obviously affect osteogenic differentiation. These data demonstrate that LKB1 plays a significant role in determining human SDSCs' adipogenic and chondrogenic differentiation, which might provide an approach for fine-tuning the direction of stem cell differentiation in tissue engineering and regeneration. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:258-268, 2020.

Anti-inflammatory Property of AMP-activated Protein Kinase

BACKGROUND

One of the many debated topics in inflammation research is whether this scenario is really an accelerated form of human wound healing and immunityboosting or a push towards autoimmune diseases. The answer requires a better understanding of the normal inflammatory process, including the molecular pathology underlying the possible outcomes. Exciting recent investigations regarding severe human inflammatory disorders and autoimmune conditions have implicated molecular changes that are also linked to normal immunity, such as triggering factors, switching on and off, the influence of other diseases and faulty stem cell homeostasis, in disease progression and development.

METHODS

We gathered around and collected recent online researches on immunity, inflammation, inflammatory disorders and AMPK. We basically searched PubMed, Scopus and Google Scholar to assemble the studies which were published since 2010.

RESULTS

Our findings suggested that inflammation and related disorders are on the verge and interfere in the treatment of other diseases. AMPK serves as a key component that prevents various kinds of inflammatory signaling. In addition, our table and hypothetical figures may open a new door in inflammation research, which could be a greater therapeutic target for controlling diabetes, obesity, insulin resistance and preventing autoimmune diseases.

CONCLUSION

The relationship between immunity and inflammation becomes easily apparent. Yet, the essence of inflammation turns out to be so startling that the theory may not be instantly established and many possible arguments are raised for its clearance. However, this study might be able to reveal some possible approaches where AMPK can reduce or prevent inflammatory disorders.

Red pepper seed water extract suppresses high-fat diet-induced obesity in C57BL/6 mice

In this study, the protective effect of red pepper seed water extract (RPS) against the obesity in high fat diet (HFD)-fed mice was investigated (HFD control group, and HFD group treated with 100 or 200 mg/kg body weight of RPS for 13 weeks). The application of RPS partially reversed the HFD-induced increases in body weight and adipose tissue weight. The patterns of the adipose tissue weights were parallel to the patterns of fat area, as measured in DXA procedure. In the adipose tissue, RPS suppressed the expression of adipogenic transcription factors and adipose marker genes. AMP-activated protein kinase activation was observed in the adipose tissue by RPS treatment. In addition, RPS improved high homeostasis model assessment of insulin resistance and hyperlipidemia in HFD fed mice. These findings suggest that RPS can be used as a potential therapeutic substance for reducing body fat and obesity related diseases.

Effects of various antimicrobial agents on multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells

Antimicrobial drugs of several classes play an important role in the treatment of bone and joint infections. In addition to fighting pathogenic microorganisms, the effects of drugs on local tissues and cells are also related to the course and prognosis of bone and joint infections. The multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) is essential for tissue repair after local injury, which is directly related to the recovery of bone, cartilage, and medullary adipose tissue. Our previous studies and the literature indicate that certain antimicrobial agents can regulate the differentiation potential of bone marrow-derived MSCs. Here, in order to systematically analyze the effects of various antimicrobial drugs on local tissue regeneration, we comprehensively review the studies on the effects of these drugs on MSC differentiation, and classify them according to the three differentiation directions (osteogenesis, chondrogenesis, and adipogenesis). Our review demonstrates the specific effects of different antimicrobial agents on bone marrow-derived MSCs and the range of concentrations at which they work, and provides a basis for drug selection at different sites of infection.

AMP-activated protein kinase complexes containing the β2 regulatory subunit are up-regulated during and contribute to adipogenesis

AMP-activated protein kinase (AMPK) is a heterotrimer of α-catalytic and β- and γ-regulatory subunits that acts to regulate cellular and whole-body nutrient metabolism. The key role of AMPK in sensing energy status has led to significant interest in AMPK as a therapeutic target for dysfunctional metabolism in type 2 diabetes, insulin resistance and obesity. Despite the actions of AMPK in the liver and skeletal muscle being extensively studied, the role of AMPK in adipose tissue and adipocytes remains less well characterised. Small molecules that selectively influence AMPK heterotrimers containing specific AMPKβ subunit isoforms have been developed, including MT47-100, which selectively inhibits complexes containing AMPKβ2. AMPKβ1 and AMPKβ2 are the principal AMPKβ subunit isoforms in rodent liver and skeletal muscle, respectively, yet the contribution of specific AMPKβ isoforms to adipose tissue function, however, remains largely unknown. This study therefore sought to determine the contribution of AMPKβ subunit isoforms to adipocyte biology, focussing on adipogenesis. AMPKβ2 was the principal AMPKβ isoform in 3T3-L1 adipocytes, isolated rodent adipocytes and human subcutaneous adipose tissue, as assessed by the contribution to total cellular AMPK activity. Down-regulation of AMPKβ2 with siRNA inhibited lipid accumulation, cellular adiponectin levels and adiponectin secretion during 3T3-L1 adipogenesis, whereas down-regulation of AMPKβ1 had no effect. Incubation of 3T3-L1 cells with MT47-100 selectively inhibited AMPK complexes containing AMPKβ2 whilst simultaneously inhibiting cellular lipid accumulation as well as cellular levels and secretion of adiponectin. Taken together, these data indicate that increased expression of AMPKβ2 is an important feature of efficient adipogenesis.

Bioactivity-Guided Isolation and Identification of Antiadipogenic Compounds in Shiya Tea (Leaves of Adinandra nitida)

Obesity is a worldwide epidemic contributing to a higher risk of developing maladies such as type 2 diabetes, heart disease, and cancer. Shiya tea (leaves of Adinandra nitida), a traditional Chinese tea, is widely consumed due to its palatable flavor and various curative effects, such as reducing blood pressure and blood lipids, as well as anti-inflammation, etc. However, no relevant research on the antiobesity effects of Shiya tea has been reported. In particular, no health-benefiting compounds, other than flavonoids, in Shiya tea have been reported. Thus, 3T3-L1 preadipocytes have been used as a bioactivity-guided identification model to verify the inhibitory effects of Shiya tea on adipogenesis, as well as to identify antiadipogenic compounds. Four triterpenoid saponins (1-4), including one new compound (2α,3α-dihydroxyursolic acid 28- O-β-d-glucopyranosyl ester, compound 1), and a flavonoid (5) have been identified using NMR (1D and 2D NMR) and liquid chromatography (LC)-MS techniques. Compound 1, the major antiadipogenic constituent with an IC₅₀ value of 27.6 μg/mL, has been identified for the first time in Shiya tea. To understand the structure-activity relationship, three hydrolytic compounds (1s, 2s, and 5s) were obtained to provide an inhibitory effect on lipid accumulation during 3T3-L1 adipocyte differentiation. The inhibitory effect of the triterpenoid (1s) possessing no sugar group decreased significantly, while the flavonoid (5s) also without a sugar group showed increased activity. In addition, the hydroxyl group position may also play a role in inhibitory efficacy.

Inhibition of lipid accumulation by the ethyl acetate fraction of Distylium racemosum in vitro and in vivo

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Lipid accumulation in the 3T3-L1 cells were inhibited by treatment with DRE.

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The expression levels of SREBP1c, PPARγ, C/EBPα, and FAS were decreased by DRE.

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HFD induced fat mice showed lower rate of weight gain and serum TG level through DRE administration.

This study confirms the anti-obesity effect of the ethyl acetate fraction of Distylium racemosum (DRE), a member of Hamamelidaceae, that naturally grows on Jeju Island, on adipocyte differentiation in 3T3-L1 cells. This study further demonstrated that DRE exhibits anti-obesity effects in C57BL/6 obese mice. The degree of adipocyte differentiation was determined using Oil red O stain; results indicated a decrease in fat globules, which was dependent on DRE concentration, when pre-adipocytes were treated with differentiation-inducing agents. In addition, this significantly reduced the expression of the adipogenic transcription factor and related genes. C57BL/6 obese mice treated with DRE showed a lower rate of body weight gain than the high-fat diet (HFD) group mice. Further, the level of serum triglyceride in the DRE treatment group was lower than that in the HFD group. The findings show that DRE are capable of suppressing adipocyte accumulation; therefore, DRE may represent a promising source of functional materials for the anti-obesity.

Lipopolysaccharide promoted proliferation and adipogenesis of preadipocytes through JAK/STAT and AMPK-regulated cPLA2 expression

The proliferation and adipogenesis of preadipocytes played important roles in the development of adipose tissue and contributed much to the processes of obesity. On the other hand, lipopolysaccharide (LPS), also known as endotoxin, is a key outer membrane component of gram-negative bacteria in the gut microbiota, and has a dominant role in linking inflammation to high-fat diet-induced metabolic syndrome. Studies suggested the potential roles of LPS in hepatic steatosis and in obese mice models. However, the molecular mechanisms underlying LPS-regulated obesity remained largely unknown. Here we reported that LPS stimulated expression of cyosolic phospholipase A2 (cPLA2), one of inflammation regulators of obesity, in the preadipocytes. Pretreatment the inhibitors of JAK2, STAT3, STAT5 or AMPK significantly reduced LPS-increased mRNA and protein expression of cPLA2 together with phosphorylation of JAK2, STAT3, STAT5 and AMPK, separately. Similarly, transfection of siRNA against JAK2 or AMPK abolished expression of cPLA2 and phosphorylation of JAK2 or AMPK together with downregulated expression of JAK2 and AMPK protein. LPS enhanced activation of STAT3 and STAT5 via JAK2-dependent manner in the preadipocytes. Transfection of JAK2 or AMPK siRNA further proofed the independence of JAK2 and AMPK in LPS-treated preadipocytes. In addition, LPS-increased DNA synthesis, cell numbers and cell viability of preadipocytes were attenuated by AACOCF3, AG490, BML-275, cPLA2 siRNA, JAK2 siRNA or AMPK siRNA. Attenuation JAK2/STAT or AMPK-dependent cPLA2 expression reduced LPS-mediated adipogenesis of preadipocytes. Stimulation of arachidonic acid or AMPK activator, A-769662, increased cell numbers and cell viability and promoted differentiation of preadipocytes. Collectively, these results indicated that LPS increased preadipocytes proliferation and adipogenesis via JAK/STAT and AMPK-dependent cPLA2 expression. The mechanisms of LPS-stimulated cPLA2 expression may be a link between bacteria and obesity and provides the molecular basis for preventing metabolic syndrome or hyperplasic obesity.

Bioactivities of EF24, a Novel Curcumin Analog: A Review

Curcumin is an attractive agent due to its multiple bioactivities. However, the low oral bioavailability and efficacy profile hinders its clinical application. To improve the bioavailability, many analogs of curcumin have been developed, among which EF24 is an excellent representative. EF24 has enhanced bioavailability over curcumin and shows more potent bioactivity, including anti-cancer, anti-inflammatory, and anti-bacterial. EF24 inhibits tumor growth by inducing cell cycle arrest and apoptosis, mainly through its inhibitory effect on the nuclear factor kappa B (NF-κB) pathway and by regulating key genes through microRNA (miRNA) or the proteosomal pathway. Based on the current structure, more potent EF24 analogs have been designed and synthesized. However, some roles of EF24 remain unclear, such as whether it induces or inhibits reactive oxygen species (ROS) production and whether it stimulates or inhibits the mitogen activated kinase-like protein (MAPK) pathway. This review summarizes the known biological and pharmacological activities and mechanisms of action of EF24.