Anti-obesity effect of sulforaphane in broccoli leaf extract on 3T3-L1 adipocytes and ob/ob mice.

The present study evaluated the anti-obesity effect of sulforaphane (SFN) and glucoraphanin (GRN) in broccoli leaf extract (BLE) on 3T3-L1 adipocytes and ob/ob mice. Based on Oil Red O staining and triglyceride (TG) assay, SFN and BLE significantly reduced (P<.05) both lipid accumulation and TG content in the differentiated 3T3-L1 adipocytes. SFN and BLE increased 2-NBDG uptake by 3T3-L1 adipocytes in a dose-dependent manner. Western blot analysis confirmed that SFN and BLE increased the phosphorylation levels of both AMPK (Thr172) and ACC (Ser79), and reduced the expression of HMGCR in liver and white adipose tissues of ob/ob mice. Histological analysis revealed that SFN and BLE ameliorated hepatic steatosis, and reduced the size of adipocyte in ob/ob mice. Treatment with SFN and BLE significantly reduced (P<.05) TG content, low-density lipoprotein (LDL) cholesterol, total cholesterol (TC), and glucose in the serum of ob/ob mice. RNA sequencing analysis showed that up- or down-regulation of 32 genes related to lipid metabolism was restored to control level in both SFN and BLE-treated ob/ob mice groups. A protein-protein interaction (PPI) network was constructed via STRING analysis, and Srebf2, Pla2g2c, Elovl5, Plb1, Ctp1a, Lipin1, Fgfr1, and Plcg1 were located in the functional hubs of the PPI network of lipid metabolism. Overall results suggest that the SFN content in BLE exerts a potential anti-obesity effect by normalizing the expression of genes related to lipid metabolism, which are up- or down-regulated in ob/ob mice.

DHA but not EPA induces the trans-differentiation of C2C12 cells into white-like adipocytes phenotype.

Muscle derived stem cells (MDSCs) and myoblast play an important role in myotube regeneration when muscle tissue is injured. However, these cells can be induced to differentiate into adipocytes once exposed to PPARγ activator like EPA and DHA that are highly suggested during pregnancy. The objective of this study aims at determining the identity of trans-differentiated cells by exploring the effect of EPA and DHA on C2C12 undergoing differentiation into brown and white adipocytes. DHA but not EPA committed C2C12 cells reprograming into white like adipocyte phenotype. Also, DHA promoted the expression of lipolysis regulating genes but had no effect on genes regulating ß-oxidation referring to its implication in lipid re-esterification. Furthermore, DHA impaired C2C12 cells differentiation into brown adipocytes through reducing the thermogenic capacity and mitochondrial biogenesis of derived cells independent of UCP1. Accordingly, DHA treated groups showed an increased accumulation of lipid droplets and suppressed mitochondrial maximal respiration and spare respiratory capacity. EPA, on the other hand, reduced myogenesis regulating genes, but no significant differences were observed in the expression of adipogenesis key genes. Likewise, EPA suppressed the expression of WAT signature genes indicating that EPA and DHA have an independent role on white adipogensis. Unlike DHA treatment, EPA supplementation had no effect on the differential of C2C12 cells into brown adipocytes. In conclusion, DHA is a potent adipogenic and lipogenic factor that can change the metabolic profile of muscle cells by increasing myocellular fat.

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.

The natural compound rutaecarpine promotes white adipocyte browning through activation of the AMPK-PRDM16 axis.

The prevalence of obesity is increasing globally and is associated with many metabolic disorders, such as type 2 diabetes and cardiovascular diseases. In recent years, a number of studies suggest that promotion of white adipose browning represents a promising strategy to combat obesity and its related metabolic disorders. The aim of this study was to identify compounds that induce adipocyte browning and elucidate their mechanism of action. Among the 500 natural compounds screened, a small molecule named Rutaecarpine, was identified as a positive regulator of adipocyte browning both in vitro and in vivo. KEGG pathway analysis from RNA-seq data suggested that the AMPK signaling pathway was regulated by Rutaecarpine, which was validated by Western blot analysis. Furthermore, inhibition of AMPK signaling mitigated the browning effect of Rutaecaripine. The effect of Rutaecaripine on adipocyte browning was also abolished upon deletion of Prdm16, a downstream target of AMPK pathway. In collusion, Rutaecarpine is a potent chemical agent to induce adipocyte browning and may serve as a potential drug candidate to treat obesity.

Strawberry (Fragaria × ananassa cv. Romina) methanolic extract promotes browning in 3T3-L1 cells.

In recent years, the conversion of white adipocytes to brown-like adipocytes by pharmacological and dietary compounds has gained attention as an effective strategy to fight obesity. Strawberry bioactive compounds present several biological activities including antioxidant, anti-inflammatory, anti-cancer, anti-atherosclerotic and antiadipogenic properties. However, to the best of our knowledge, the possible role of strawberry bioactive compounds in white adipose tissue (WAT) browning has never been explored. Our results demonstrated that a strawberry methanolic extract (SE) significantly reduced 3T3-L1 pre-adipocytes differentiation, and down-regulated the mRNA expression of the adipogenic transcription factors CCAAT/enhancer-binding protein (C/REB- α) and peroxisome proliferation-activated receptor (PPAR-γ). It also down-regulated the mRNA expression of resistin and angiotensinogen, two genes considered as markers of white adipocytes, while increased the mRNA expression of pyruvate dehydrogenase lipoamide kinase isozyme 4 (PDK4) and uncoupling protein 1 (UCP1) which, conversely, are brown adipocyte-specific markers. Likewise, SE stimulated AMP-activated protein kinase (AMPKα), sirtuin 1 (Sirt1) and the peroxisome proliferator activated receptor gamma coactivator 1-alpha (PGC-1α), suggesting a possible increase in mitochondrial biogenesis. It also stimulated oxygen consumption rate and uncoupled respiration. Taken together, all these results suggest that SE induces brown fat-like phenotype in 3T3-L1 cells and may have potential therapeutic implications for treatment and/or prevention of obesity.

Regulation of thermogenic capacity in brown and white adipocytes by the prebiotic high-esterified pectin and its postbiotic acetate.

OBJECTIVES: High-esterified pectin (HEP) is a prebiotic able to modulate gut microbiota, associated with health-promoting metabolic effects in glucose and lipid metabolism and adipostatic hormone sensitivity. Possible effects regulating adaptive thermogenesis and energy waste are poorly known. Therefore, we aimed to study how physiological supplementation with HEP is able to affect microbiota, energy metabolism and adaptive thermogenic capacity, and to contribute to the healthier phenotype promoted by HEP supplementation, as previously shown. We also attempted to decipher some of the mechanisms involved in the HEP effects, including in vitro experiments. SUBJECTS AND EXPERIMENTAL DESIGN: We used a model of metabolic malprogramming consisting of the progeny of rats with mild calorie restriction during pregnancy, both under control diet and an obesogenic (high-sucrose) diet, supplemented with HEP, combined with in vitro experiments in primary cultured brown and white adipocytes treated with the postbiotic acetate. RESULTS: Our main findings suggest that chronic HEP supplementation induces markers of brown and white adipose tissue thermogenic capacity, accompanied by a decrease in energy efficiency, and prevention of weight gain under an obesogenic diet. We also show that HEP promotes an increase in beneficial bacteria in the gut and peripheral levels of acetate. Moreover, in vitro acetate can improve adipokine production, and increase thermogenic capacity and browning in brown and white adipocytes, respectively, which could be part of the protection mechanism against excess weight gain observed in vivo. CONCLUSION: HEP and acetate stand out as prebiotic/postbiotic active compounds able to modulate both brown-adipocyte metabolism and browning and protect against obesity.

Betaine Supplementation Enhances Lipid Metabolism and Improves Insulin Resistance in Mice Fed a High-Fat Diet.

Obesity is a major driver of metabolic diseases such as nonalcoholic fatty liver disease, certain cancers, and insulin resistance. However, there are no effective drugs to treat obesity. Betaine is a nontoxic, chemically stable and naturally occurring molecule. This study shows that dietary betaine supplementation significantly inhibits the white fat production in a high-fat diet (HFD)-induced obese mice. This might be due to betaine preventing the formation of new white fat (WAT), and guiding the original WAT to burn through stimulated mitochondrial biogenesis and promoting browning of WAT. Furthermore, dietary betaine supplementation decreases intramyocellular lipid accumulation in HFD-induced obese mice. Further analysis shows that betaine supplementation reduced intramyocellular lipid accumulation might be associated with increasing polyunsaturated fatty acids (PUFA), fatty acid oxidation, and the inhibition of fatty acid synthesis in muscle. Notably, by performing insulin-tolerance tests (ITTs) and glucose-tolerance tests (GTTs), dietary betaine supplementation could be observed for improvement of obesity and non-obesity induced insulin resistance. Together, these findings could suggest that inhibiting WAT production, intramyocellular lipid accumulation and inflammation, betaine supplementation limits HFD-induced obesity and improves insulin resistance.

Lack of effects of myo-inositol on metabolism of primary rat adipocytes.

Myo-inositol is a ubiquitous cyclitol, has an important regulatory role, and its intracellular depletion is associated with pathological changes. Effects of myo-inositol on adipose tissue are poorly elucidated. In this report, short-term influence of 20, 100, and 500 µM myo-inositol on metabolism of the isolated rat adipocytes was studied. Cells were incubated for 90 min with glucose and insulin with or without myo-inositol and glucose conversion to lipids and lactate release were measured. Moreover, effects of myo-inositol on lipolysis and on the antilipolytic action of insulin were also studied. It was demonstrated that lipogenesis and lactate release were unchanged by myo-inositol. Moreover, lipolytic response to epinephrine and dibutyryl-cAMP was also unchanged. Myo-inositol was also found to be without influence on the antilipolytic action of insulin. Results of this study show that metabolism of the isolated rat adipocytes is not affected by short-term exposure of these cells to myo-inositol.

Immobilized tannase treatment alters polyphenolic composition in teas and their potential anti-obesity and hypoglycemic activities in vitro.

The aim of this work was to assess the effect of immobilized-tannase treatment on black, green, white and mate tea components and on their bioactivities relevant to obesity. Tannase treatment caused predictable changes in polyphenol composition with substantial reduction in galloylated catechins in green, white and black tea. Mate tea, which is rich in chlorogenic acids, was much less affected by tannase treatment although some degradation of caffeoyl quinic acid derivatives was noted. The original tea samples were effective in inhibiting digestive enzymes in vitro. They inhibited amylase activity, some with IC50 values ∼70 µg mL(-1), but were much less effective against α-glucosidase. They also inhibited lipase activity in vitro and caused dose-dependent reductions in lipid accumulation in cultured adipocytes. The bio-transformed tea samples generally matched the effectiveness of the original samples but in some cases they were markedly improved. In particular, tannase treatment reduced the IC50 value for amylase inhibition for green tea and white tea by 15- and 6-fold respectively. In addition, the bio-transformed samples were more effective than the original samples in preventing lipid accumulation in adipocytes. These in vitro studies indicate that bio-transformed tea polyphenols could assist in the management of obesity through improvement in energy uptake and lipid metabolism and also indicate that biotechnological modification of natural food molecules can improve the benefits of a common beverage such as tea.

Effects of quercetin, a natural phenolic compound, in the differentiation of human mesenchymal stem cells (MSC) into adipocytes and osteoblasts.

Natural phenols may have beneficial properties against oxidative stress, which is associated with aging and major chronic aging-related diseases, such as loss of bone mineral mass (osteoporosis) and diabetes. The main aim of this study was to analyze the effect of quercetin, a major nutraceutical compound present in the "Mediterranean diet", on mesenchymal stem-cell (MSC) differentiation. Such cells were induced to differentiate into osteoblasts or adipocytes in the presence of two quercetin concentrations (0.1 and 10µM). Several physiological parameters and the expression of osteoblastogenesis and adipogenesis marker genes were monitored. Quercetin (10µM) inhibited cell proliferation, alkaline phosphatase (ALPL) activity and mineralization, down-regulating the expression of ALPL, collagen type I alpha 1 (COL1A1) and osteocalcin [bone gamma-carboxyglutamate protein (BGLAP)] osteoblastogenesis-related genes in MSC differentiating into osteoblasts. Moreover, in these cultures, CCAAT/enhancer-binding protein alpha (CEBPA) and peroxisome proliferator-activated receptor gamma 2 (PPARG2) adipogenic genes were induced, and cells differentiated into adipocytes were observed. Quercetin did not affect proliferation, but increased adipogenesis, mainly at 10-µM concentration in MSC induced to differentiate to adipocytes. ß- and γ-catenin (plakoglobin) nuclear levels were reduced and increased, respectively, in quercetin-treated cultures. This suggests that the effect of high concentration of quercetin on MSC osteoblastic and adipogenic differentiation is mediated via Wnt/ß-catenin inhibition. In conclusion, quercetin supplementation inhibited osteoblastic differentiation and promoted adipogenesis at the highest tested concentration. Such possible adverse effects of high quercetin concentrations should be taken into account in nutraceutical or pharmaceutical strategies using such flavonol.

Cascade regulation of PPARγ(2) and C/EBPα signaling pathways by celastrol impairs adipocyte differentiation and stimulates lipolysis in 3T3-L1 adipocytes.

OBJECTIVE: Celastrol, a triterpene from the root bark of the Chinese medicinal plant Tripterygium wilfordii, has been shown to exhibit anti-oxidant, anti-inflammatory, anti-cancer and insecticidal activities. Also, it has been demonstrated that celastrol has obesity-controlling effects in diet-induced obesity mice. However, direct evidence that celastrol contributes to the development of adipocyte differentiation and lipolysis has not been fully elucidated. Moreover, no previous studies have evaluated whether celastrol may regulate adipogenic transcriptional markers in adipocytes. MATERIALS/METHODS: In order to address the questions above, we extended previous observations and investigated in vitro celastrol signaling study whether celastrol may regulate differentiation, lipolysis and key adipogenic transcriptional pathways in 3T3-L1 adipocytes. RESULTS: Treatment of celastrol not only inhibited adipocyte differentiation (lipid accumulation, glyceraldehyde-3-phosphate dehydrogenase activity and triglyceride content) but also increased lipolysis (glycerol release and free fatty acid release) in 3T3-L1 adipocytes. In addition, all celastrol-regulated functional activities were controlled by PPARγ(2) and C/EBPα signaling pathways in duration of celastrol's treatment in 3T3-L1 adipocytes. CONCLUSION: Our initial data from in vitro celastrol signaling studies suggest novel insights into the role of PPARγ(2) and C/EBPα as probable mediators of the action of celastrol in regulating adipocyte differentiation and lipolysis in 3T3-L1 adipocytes.

Glucose- and Triglyceride-lowering Dietary Penta-O-galloyl-α-D-Glucose Reduces Expression of PPARγ and C/EBPα, Induces p21-Mediated G1 Phase Cell Cycle Arrest, and Inhibits Adipogenesis in 3T3-L1 Preadipocytes.

Plant polyphenols, such as hydrolysable tannins, are present in the human diet and known to exhibit anti-diabetic and anti-obesity activity. We previously reported that the representative hydrolysable tannin compound α-penta-galloyl-glucose (α-PGG) is a small molecule insulin mimetic that, like insulin, binds to insulin receptor (IR) and activates the IR-Akt-GLUT4 signaling pathway to trigger glucose transport and reduce blood glucose levels in db/db and ob/ob diabetic mice. However, its effects on adipogenesis and lipid metabolism were not known. In this study, high fat diet (HFD)-induced diabetic and obese mice were treated with α-PGG to determine its effects on blood glucose and triglycerides. 3T3-L1 preadipocytes were used as a cell model for identifying the anti-adipogenic activity of α-PGG at molecular and cellular levels as a first step in elucidating the mechanism of action of the compound. In vivo, oral administration of α-PGG significantly reduced levels of blood glucose, triglyceride, and insulin in HFD-induced diabetic/obese mice (P<0.05). In vitro, α-PGG inhibited the differentiation of 3T3-L1 preadipocytes into mature adipocytes. α-PGG suppressed the expression of positive adipogenic factors PPARγ C/EBPα and mTOR and augmented the negative adipogenic factor Pref-1. Furthermore, α-PGG induced upregulation of p21 and G1 phase cell cycle arrest. In contrast, adipogenic signaling pathways mediated by insulin, the cAMP response element binding protein (CREB) and glucocorticoid receptor (GR), were not inhibited. RNAi knockdown of p21 led to a 4-fold increase in triglyceride level in 3T3-L1 preadipocytes treated with MDI and α-PGG compared to regular preadipocytes. These results indicate, for the first time, that α-PGG is blood triglyceride- and glucose-lowering in HFD-induced obese and diabetic mice. It selectively inhibited some but not all major adipogenic pathways as well as the mTOR-p21-mediated cell cycle regulatory pathway. It is very likely that these apparently diverse but coordinated activities together inhibited adipogenesis. These results expand our knowledge on how PGG works in adipocytes and further confirm that α-PGG functions as an orally-deliverable natural insulin mimetic with adipogenetic modulatory functions.

Dieckol, a major phlorotannin in Ecklonia cava, suppresses lipid accumulation in the adipocytes of high-fat diet-fed zebrafish and mice: Inhibition of early adipogenesis via cell-cycle arrest and AMPKα activation.

SCOPE: Dieckol is a major polyphenol of Ecklonia cava. This study demonstrates a mechanistic role for dieckol in the suppression of lipid accumulation using three models. METHODS AND RESULTS: Mice were split into four experimental groups (n = 10 per group): normal diet, high-fat diet (HFD), and dieckol-supplemented diets. Dieckol-supplemented mice groups showed a significant decrease of body weight gain (38%) as well as fats of organs including epididymal (45%) compared with a HFD-fed group. LDL cholesterol level was reduced by 55% in dieckol-supplemented group. Adipogenic factors and lipid synthetic enzymes were analyzed via real-time PCR or immunoblotting. Dieckol regulated mRNA expressions of early adipogenic genes in 3T3-L1 cells. These results were reflected in downregulation of late adipogenic factors, resulting in a decrease in triacylglycerol content. These data were also verified in zebrafish and mouse models. Dieckol activated AMP-activated protein kinase α (AMPKα) signaling to inhibit lipid synthesis in 3T3-L1 and mouse model. Dieckol was also shown to inhibit mitotic clonal expansion via cell-cycle arrest. CONCLUSION: Our data demonstrate that dieckol inhibits lipid accumulation via activation of AMPKα signaling and cell-cycle arrest.

Comprehensive molecular characterization of human adipocytes reveals a transient brown phenotype.

BACKGROUND: Functional brown adipose tissue (BAT), involved in energy expenditure, has recently been detected in substantial amounts in adults. Formerly overlooked BAT has now become an attractive anti-obesity target. METHODS AND RESULTS: Molecular characterization of human brown and white adipocytes, using a myriad of techniques including high-throughput RNA sequencing and functional assays, showed that PAZ6 and SW872 cells exhibit classical molecular and phenotypic markers of brown and white adipocytes, respectively. However, the pre-adipocyte cell line SGBS presents a versatile phenotype. A transit expression of classical brown markers such as UCP1 and PPARγ peaked and declined at day 28 post-differentiation initiation. Conversely, white adipocyte markers, including Tcf21, showed reciprocal behavior. Interestingly, leptin levels peaked at day 28 whereas the highest adiponectin mRNA levels were detected at day 14 of differentiation. Phenotypic analysis of the abundance and shape of lipid droplets were consistent with the molecular patterns. Accordingly, the oxidative capacity of SGBS adipocytes peaked on differentiation day 14 and declined progressively towards differentiation day 28. CONCLUSIONS: Our studies have unveiled a new phenotype of human adipocytes, providing a tool to identify molecular gene expression patterns and pathways involved in the conversion between white and brown adipocytes.

BAY 41-2272 activates host defence against local and disseminated Candida albicans infections

In our previous study, we have found that 5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]-pyrimidin-4-ylamine (BAY 41-2272), a guanylate cyclase agonist, activates human monocytes and the THP-1 cell line to produce the superoxide anion, increasing in vitro microbicidal activity, suggesting that this drug can be used to modulate immune functioning in primary immunodeficiency patients. In the present work, we investigated the potential of the in vivo administration of BAY 41-2272 for the treatment of Candida albicans and Staphylococcus aureus infections introduced via intraperitoneal and subcutaneous inoculation. We found that intraperitoneal treatment with BAY 41-2272 markedly increased macrophage-dependent cell influx to the peritoneum in addition to macrophage functions, such as spreading, zymosan particle phagocytosis and nitric oxide and phorbol myristate acetate-stimulated hydrogen peroxide production. Treatment with BAY 41-2272 was highly effective in reducing the death rate due to intraperitoneal inoculation of C. albicans, but not S. aureus. However, we found that in vitro stimulation of peritoneal macrophages with BAY 41-2272 markedly increased microbicidal activities against both pathogens. Our results show that the prevention of death by the treatment of C. albicans-infected mice with BAY 41-2272 might occur primarily by the modulation of the host immune response through macrophage activation. .

Inhibitory effects of tannic acid in the early stage of 3T3-L1 preadipocytes differentiation by down-regulating PPARγ expression.

Obesity is a medical condition of excess body fat negatively influencing morbidity and mortality via non-communicable disease risks. Adipogenesis, the process in which preadipocytes differentiate into adipocytes, plays a pivotal role in obesity. Our previous study proved that tannic acid (TA) showed anti-adipogenesis effect in 3T3-L1 preadipocytes. However, the precise mechanism involved in the inhibition in adipocytes differentiation by TA is unclear, and thus this is the subject of the present investigation. In this study, we determined the effect of TA on different stages of 3T3-L1 preadipocytes differentiation, and found that when treating in the early stage of differentiation, TA reduced lipid accumulation significantly. However, TA did not reduce lipid accumulation when treating in mid- and late-stages of adipocyte differentiation. To further study which gene TA had an impact on in the early stage of differentiation, we identified a number of genes associated with lipid metabolism. The results showed that compared to the control group, the mRNA levels of FAS, C/EBPα, and PPARγ were significantly decreased (p < 0.05), whereas the mRNA levels of adipsin, ap2 were increased (p < 0.05). However, TA had no effect on mRNA levels of ACC1 and ACC2. Western blot results showed that TA down-regulated the expression of PPARγ, which is a major factor in preadipocyte differentiation. In addition, TA did not affect the PI3 K/AKT pathway. These results indicate that the anti-adipogenesis effect of TA involves down-regulation of PPARγ in the early stage of 3T3-L1 preadipocyte differentiation. Some potential limitations of this study should be considered. All the results in this study were based on cell experiments. However, the human bioavailability of TA is not clear. In the present study, the concentration of TA was 5 µM; therefore, there were concerns about whether oral intake of TA could reach the effective concentrations. This important point needs to be clarified in vivo.

Quercetin-rich onion peel extract suppresses adipogenesis by down-regulating adipogenic transcription factors and gene expression in 3T3-L1 adipocytes.

BACKGROUND: Onion peel contains a high amount of quercetin, which has been reported to have anti-cholesterol, antithrombotic and insulin-sensitizing properties. This study aimed to elucidate the anti-adipogenic effects of quercetin-rich onion peel extract (OPE) and to compare it with commercially available quercetin using 3T3-L1 preadipocytes. RESULTS: Without affecting cell viability, both OPE and quercetin averted adipogenesis, as characterized by dose-dependent decreases in intracellular triglyceride content and glycerol 3-phosphate dehydrogenase activity, but the effect was more pronounced with OPE than with quercetin. The mRNA expression levels of key adipogenic genes such as PPARγ, C/EBPα, FABP4, aP2 and LPL were decreased in a dose-dependent manner by both OPE and quercetin. CONCLUSION: The results indicate that OPE treatment significantly prevents intracellular lipid accumulation via hyperactivation of genes regulating lipolysis as compared with quercetin alone.

An in vitro study reveals nutraceutical properties of Ananas comosus (L.) Merr. var. Mauritius fruit residue beneficial to diabetes.

BACKGROUND: Rapid urbanisation and nutritional transition is fuelling the increased global incidence of type 2 diabetes. Pineapple fruit residue was explored for its nutraceutical properties as an alternative or adjunct to currently available treatment regime. Ethyl acetate and methanolic extracts of pineapple fruit residue were evaluated for anti-diabetic activity in cell free and cell based systems. Specifically, we assessed: (1) antioxidant potential, (2) anti-glycation potential, (3) carbohydrate digestive enzyme inhibition, and (4) lipid accumulation and glycerol-3-phosphate dehydrogenase activity in differentiating 3T3-L1 cells. RESULTS: The active components in the ethyl acetate and methanolic extracts were identified as sinapic acid, daucosterol, 2-methylpropanoate, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, methyl 2-methylbutanoate and triterpenoid ergosterol using DART/HRMS and ESI/HRMS. Micronutrient analysis revealed the presence of magnesium, potassium and calcium. Adipogenic potential, anti-glycation property of the ethyl acetate extract, and DNA damage protection capacity of the methanolic extract are promising. CONCLUSION: Results from this study clearly indicate that pineapple fruit residue could be utilised as a nutraceutical against diabetes and related complications.

γ-Tocotrienol induced cell cycle arrest and apoptosis via activating the Bax-mediated mitochondrial and AMPK signaling pathways in 3T3-L1 adipocytes.

This study aimed to examine the anti-proliferative effects of α-, γ- and δ-tocotrienols (αT3, γT3 and δT3), and α-tocopherol on 3T3-L1 adipocytes. Results showed that compared with other vitamin E analogues, γT3 demonstrated the most potent anti-proliferative effect on 3T3-L1 cells. It significantly caused a reduction in mitochondrial membrane potential (Δψm) and an increase in ROS formation, as well as inducing cell apoptosis and cell cycle arrest at S phase. Further studies showed that it down-regulated Bcl-2 and PPAR-γ expression, suppressed Akt and ERK activation and phosphorylation, and caused cytochrome c release from mitochondria to cytosol, whereas it up-regulated CD95 (APO-1/CD95) and Bax expression, and caused caspase-3 and JNK activation, PARP cleavage and AMPK phosphorylation. Pretreatments with caspase-3 (z-DEVD-fmk) and AMPK (CC) inhibitors significantly suppressed the γT3-induced ROS production and cell death. Caspase-3 inhibitor also efficiently blocked CD95 (APO-1/CD95) and Bax expression, caspase-3 activation and PARP cleavage, whereas antioxidant N-acetyl-l-cysteine, AMPK inhibitor and AMPK siRNA effectively blocked the AMPK phosphorylation. Taken together, these results conclude that the potent anti-proliferative and anti-adipogenic effects of γT3 on 3T3-L1 adipocytes could be through the Bax-mediated mitochondrial and AMPK signaling pathways.

Sasa quelpaertensis Nakai extract and its constituent p-coumaric acid inhibit adipogenesis in 3T3-L1 cells through activation of the AMPK pathway.

In this study, we investigated the effects of Sasa quelpaertensis Nakai extract (SQE) and its main constituent, p-coumaric acid, on adipogenesis in 3T3-L1 cells. SQE markedly inhibited adipogenesis by downregulating the expression of CCAAT/enhancer-binding protein α (C/EBPα), peroxisome proliferator-activated receptor γ (PPARγ), sterol regulatory element-binding protein-1c (SREBP-1c), and aP2. It also decreased the expression of fatty acid synthase (FAS) and adiponectin mRNAs in differentiating adipocytes. SQE increased AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) phosphorylation during the early phase of MDI-induced differentiation, suggesting that SQE exerted its anti-adipogenic effect via AMPK activation at an early stage of the differentiation process. p-Coumaric acid suppressed adipogenesis by attenuating the expression of C/EBPα, PPARγ, and SREBP-1c during the late phase of MDI-induced differentiation. In addition, p-coumaric acid increased the phosphorylation of AMPK and ACC, and the expression of carnitine palmitoyl transferase-1 (CPT-1) mRNA, in fully differentiated adipocytes, indicating that it promotes fatty acid ß-oxidation via AMPK signaling. Taken together, our data suggest that SQE and p-coumaric acid might have the anti-obesitic effects via AMPK pathway in 3T3-L1 cells.