Effects of quercetin on cell differentiation and adipogenesis in 3T3-L1 adipocytes

Modification of adipogenesis and oxidative stress by quercetin: positive or negative impact on adipose tissue metabolism of obese diabetic Zucker rats?

Reactive oxygen species (ROS) play a key role in the regulation of adipogenesis. The aim of our study was to investigate the effect of quercetin (QCT) supplement on obese adipose tissue metabolism of 30-week-old diabetic Zucker rats (ZDF), not well examined yet. QCT was administered orally at dose of 20 mg/kg body weight/day for 6 weeks. Adipocytes from subcutaneous adipose tissue (ScWAT) were isolated and their size was evaluated by light microscopy. Gene expression of adipogenic markers in subcutaneous and visceral adipose tissue was determined by real-time PCR and expression of proteins involved in lipid and glucose metabolism was determined in ScWAT by immunoblotting. Obese ZDF rats suffered from diabetes, hyperinsulinemia and had higher index HOMA-IR (Homeostatic Model Assessment for Insulin Resistance). Treatment with QCT had no significant impact on these metabolic disorders in genetic model of obesity and type 2 diabetes used in our study. Nevertheless, QCT reduced expression of inflammatory cytokine tumour necrosis factor alpha in ScWAT and also visceral adipose tissue and up-regulated expression of anti-inflammatory adiponectin in ScWAT. A shift in redox equilibrium was detected via inhibition of pro-oxidant genes by QCT. Furthermore, QCT reduced adipocyte size in ScWAT, down-regulated expression of fatty acid synthase and adipogenic markers, and moreover stimulated expression of proteolytic enzymes. These changes likely resulted in reduced fat deposition in ScWAT, which was reflected in the elevated circulated levels of free fatty acids in QCT-treated obese ZDF rats compared with obese untreated controls. This increase could, at least in part, explain why we did not observe an improvement in systemic metabolic health by QCT in our model. In conclusion, our study suggests that preventive treatment with QCT might be more effective than its administration in the stage of fully developed diabetes, and further research in this area is needed.

Inhibitory effects of cashew Anacardium occidentale L. kernel, apple, and shell extracts on lipid accumulation and adipogenesis in 3T3-L1 adipocytes

Obesity, a major risk factor for various metabolic diseases, often results in dysfunctional white adipose tissue and altered adipogenesis leading to ectopic fat accumulation, inflammation, and insulin resistance. On the other hand, cashew (Anacardium occidentale L.) nut worldwide consumption and production is increasing steadily, which augments the mass of byproducts to be discarded. Indeed, cashew apples and cashew shells have shown potent effects to lower adiposity weight in human and animal models. However, the direct effect on adipocyte differentiation still remains unexplored. Therefore, this study aimed to investigate the biological effect of cashew nut or kernel (CK), dried cashew apple (DA), and cashew shell (SH) ethanolic extracts on 3T3-L1 adipocyte differentiation and lipid accumulation. SH showed strong inhibition on adipocyte differentiation by downregulating transcription factors, PPARγ, C/EBPα, and SREBP-1. DA also inhibited the transcription factors accompanied by reduced lipid accumulation, while proteins for de novo lipogenesis were unchanged. Finally, CK did not alter any markers in adipocyte differentiation, however, interestingly adiponectin level was significantly increased. Concisely, our findings showed that CK ameliorates adiponectin production without interfering adipogenesis, while DA lowers lipid accumulation and SH suppresses adipogenesis.

Unlocking the Bioactive Potential and Exploring Novel Applications for Portuguese Endemic Santolina impressa

The infusion of Santolina impressa, an endemic Portuguese plant, is traditionally used to treat various infections and disorders. This study aimed to assess its chemical profile by HPLC-DAD-ESI-MSn and validate its anti-inflammatory potential. In addition, the antioxidant capacity and effects on wound healing, lipogenesis, melanogenesis, and cellular senescence, all processes in which a dysregulated inflammatory response plays a pivotal role, were unveiled. The anti-inflammatory potential was assessed in lipopolysaccharide (LPS)-stimulated macrophages, cell migration was determined using a scratch wound assay, lipogenesis was assessed on T0901317-stimulated keratinocytes and melanogenesis on 3-isobutyl-1-methylxanthine (IBMX)-activated melanocytes. Etoposide was used to induce senescence in fibroblasts. Our results point out a chemical composition predominantly characterized by dicaffeoylquinic acids and low amounts of flavonols. Regarding the infusion's bioactive potential, an anti-inflammatory effect was evident through a decrease in nitric oxide production and inducible nitric oxide synthase and pro-interleukin-1β protein levels. Moreover, a decrease in fibroblast migration was observed, as well as an inhibition in both intracellular lipid accumulation and melanogenesis. Furthermore, the infusion decreased senescence-associated β-galactosidase activity, γH2AX nuclear accumulation and both p53 and p21 protein levels. Overall, this study confirms the traditional uses of S. impressa and ascribes additional properties of interest in the pharmaceutical and dermocosmetics industries.

Targeting dysregulated lipid metabolism in the tumor microenvironment

The reprogramming of lipid metabolism and its association with oncogenic signaling pathways within the tumor microenvironment (TME) have emerged as significant hallmarks of cancer. Lipid metabolism is defined as a complex set of molecular processes including lipid uptake, synthesis, transport, and degradation. The dysregulation of lipid metabolism is affected by enzymes and signaling molecules directly or indirectly involved in the lipid metabolic process. Regulation of lipid metabolizing enzymes has been shown to modulate cancer development and to avoid resistance to anticancer drugs in tumors and the TME. Because of this, understanding the metabolic reprogramming associated with oncogenic progression is important to develop strategies for cancer treatment. Recent advances provide insight into fundamental mechanisms and the connections between altered lipid metabolism and tumorigenesis. In this review, we explore alterations to lipid metabolism and the pivotal factors driving lipid metabolic reprogramming, which exacerbate cancer progression. We also shed light on the latest insights and current therapeutic approaches based on small molecular inhibitors and phytochemicals targeting lipid metabolism for cancer treatment. Further investigations are worthwhile to fully understand the underlying mechanisms and the correlation between altered lipid metabolism and carcinogenesis.

Inhibition of lipid droplet accumulation by Solanum nigrum by suppressing adipogenesis and inducing lipolysis, thermogenesis and autophagy in 3T3‑L1 cells

It has been reported that Solanum nigrum exhibits anti-obesity effects in animal models induced by a high-fat diet. However, research on how Solanum nigrum exerts its anti-obesity effects is currently limited. Thus, the present study focused on identifying the mechanism of action associated with the anti-obesity activity of Solanum nigrum aerial part (SNAP), which significantly inhibited the accumulation of lipid droplets in differentiating 3T3-L1 cells. Intracellular lipid accumulation in 3T3-L1 cells was analyzed by Oil-Red O staining and glycerol content was analyzed using an ELISA kit. In addition, changes in protein expression within 3T3-L1 cells were analyzed using western blot analysis. It decreased the expression level of adipogenic proteins such as CCAAT/enhancer-binding protein α, Peroxisome proliferator-activated receptor γ, fatty acid binding protein 4, and adiponectin. In addition, SNAP increased the expression levels of lipolytic proteins, such as adipose triglyceride lipase and hormone-sensitive lipase, while decreasing perilipin-1. The treatment of fully differentiated 3T3-L1 cells increased the free glycerol levels. SNAP treatment resulted in increased AMP-activated protein kinase phosphorylation and the expression levels of thermogenic proteins (peroxisome proliferator-activated receptor-γ coactivator 1-α, PR domain containing 16 and uncoupling protein 1) and an autophagic protein (LC3-II). Overall, these results suggested that SNAP inhibited lipid droplet accumulation by suppressing adipogenesis and promoting lipolysis, thermogenesis and autophagy.

Quercetin inhibits body weight gain and adipogenesis via matrix metalloproteinases in mice fed a high-fat diet

BACKGROUND/OBJECTIVES

Limited studies reported that quercetin inhibited adipogenesis and neovascularization by inhibiting matrix metalloproteinases (MMPs) activity, but such mechanisms have not been elucidated in animal experiments. In this study, we investigated the inhibitory effects of quercetin on weight gain and adipose tissue growth through the regulation of mRNA expressions of adipogenic transcription factors and MMPs in mice fed a high-fat diet (HFD).

MATERIALS/METHODS

Five-wk-old C57BL/6J mice were fed a normal diet (ND), HFD, HFD containing 0.05% of quercetin (HFQ0.05), or HFD containing 0.15% of quercetin (HFQ0.15) for 16 wks. Glycerol-3-phosphate dehydrogenase (GPDH) activity was measured using a commercial kit. The mRNA expressions of transcription factors related to adipocyte differentiation were determined by real-time polymerase chain reaction (PCR). The mRNA expressions of MMPs and concentrations of MMPs were measured by real-time PCR and enzyme-linked immunosorbent assay kit, respectively.

RESULTS

Quercetin intake reduced body weight gain and epididymal adipose tissue weights (P < 0.05). GPDH activity was higher in the HFD group than in the ND group but lower in the quercetin groups (P < 0.05). The mRNA expressions of CCAAT/enhancer binding protein β (C/EBPβ), C/EBPα, peroxisome proliferator-activated receptor γ, and fatty acid-binding protein 4 were lower in the quercetin groups than in the HFD group (P < 0.05). Similarly, the mRNA expression and concentrations of MMP-2 and MMP-9 were significantly lower in the quercetin groups than in the HFD group (P < 0.05).

CONCLUSION

The study confirms that quercetin suppresses body weight gain and adipogenesis by inhibiting transcription factors related to adipocyte differentiation and MMPs (MMP-2 and MMP-9), in mice fed a HFD.

Influence of Polyphenols on Adipose Tissue: Sirtuins as Pivotal Players in the Browning Process

Adipose tissue (AT) can be classified into two different types: (i) white adipose tissue (WAT), which represents the largest amount of total AT, and has the main function of storing fatty acids for energy needs and (ii) brown adipose tissue (BAT), rich in mitochondria and specialized in thermogenesis. Many exogenous stimuli, e.g., cold, exercise or pharmacological/nutraceutical tools, promote the phenotypic change of WAT to a beige phenotype (BeAT), with intermediate characteristics between BAT and WAT; this process is called "browning". The modulation of AT differentiation towards WAT or BAT, and the phenotypic switch to BeAT, seem to be crucial steps to limit weight gain. Polyphenols are emerging as compounds able to induce browning and thermogenesis processes, potentially via activation of sirtuins. SIRT1 (the most investigated sirtuin) activates a factor involved in mitochondrial biogenesis, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), which, through peroxisome proliferator-activated receptor γ (PPAR-γ) modulation, induces typical genes of BAT and inhibits genes of WAT during the transdifferentiation process in white adipocytes. This review article aims to summarize the current evidence, from pre-clinical studies to clinical trials, on the ability of polyphenols to promote the browning process, with a specific focus on the potential role of sirtuins in the pharmacological/nutraceutical effects of natural compounds.

Antiangiogenic Potential of Troxerutin and Chitosan Loaded Troxerutin on Chorioallantoic Membrane Model

Angiogenesis is crucial to the development of cancer because it allows the transport of oxygen, nutrients, and growth factors as well as the spread of tumors to distant organs. Inhibitors of angiogenesis prevent the formation of blood vessels that allow tumor cells to shrink, rather than promote tumor growth. Chitosan acts as a carrier for many drugs, since the compound has various properties such as biodegradable, less toxicity, more stable, simple, easy to prepare, and biocompatible. The aim of the current study was to evaluate the efficacy of chitosan nanoparticles encapsulated with troxerutin (Chi-Trox NPs) against angiogenesis and cancer in ova chick chorioallantoic membrane (CAM) model. Chi-Trox NPs were synthesized using a nanoprecipitation method and were characterized by various analyses. 24 hours' fertilized eggs (6 eggs/group) were treated with native Trox and Chi-Trox NPs for 5 days. The antiangiogenic activity was evaluated by morphometric, histopathological, immunohistochemical (CD104 and vimentin), and mRNA expression of MMP and FGF2 using RT-PCR. The anticancer activity was evaluated by histopathological, immunohistochmical (CD44), and mRNA expression of FGF2 and MMP. The synthesized chitosan NPs were successfully encapsulated with troxerutin, and the loading efficiency of chitosan NPs was found to be 86.4 ± 0.12% and 13.2 ± 0.16% respectively. Morphometric analysis of Chi-Trox NPs showed a considerable decrease in the number of blood vessels compared with control and native Trox. The histopathological observation of CAM confirmed that Chi-Trox NPs induce a significant reduction in inflammatory cells and the thickness of blood capillaries compared to control and native Trox. The immunohistochemical evaluation of CAM revealed Chi-Trox decreased CD104, vimentin and CD44 protein levels were compared with control and native Trox. Furthermore, the mRNA expression levels of FGF2 and MMP were significantly downregulated compared to their native forms. From the obtained results, Chi-Trox NPs possess significant inhibition of angiogenesis and can be used as therapeutic agents for cancer in the future.

Functional Complementation of Anti-Adipogenic Phytonutrients for Obesity Prevention and Management

Obesity is an established risk factor for metabolic disease. This study explores the functional complementation of anti-adipogenic phytonutrients for obesity prevention and management. Nine phytonutrients were selected based on their ability to affect the expression of one or more selected adipogenic biomarker proteins. The phytonutrients include berberine, luteolin, resveratrol, fisetin, quercetin, fucoidan, epigallocatechin gallate, hesperidin, and curcumin. The selected adipogenic biomarker proteins include PPARɣ, SREBP1c, FASN, PLIN1, FABP4, and β-catenin. Individually, phytonutrients had variable effects on the expression level of selected adipogenic biomarker proteins. Collectively, the functional complementation of nine phytonutrients suppressed de novo fatty acid biosynthesis via the negative regulation of PPARɣ, FASN, PLIN1, and FABP4 expression; activated glycolysis via the positive regulation of SREBP1c expression; and preserved cell–cell adhesion via the inhibition of β-catenin degradation. In primary human subcutaneous preadipocytes, the composition of nine phytonutrients had more potent and longer lasting anti-adipogenic effects compared to individual phytonutrients. In a diet-induced obesity murine model, the composition of nine phytonutrients improved glucose tolerance and reduced weight gain, liver steatosis, visceral adiposity, circulating triglycerides, low-density lipoprotein cholesterol, and inflammatory cytokines and chemokines. The functional complementation of anti-adipogenic phytonutrients provides an effective approach toward engineering novel therapeutics for the prevention and management of obesity and metabolic syndrome.