Mak Soon Lee

Inhibitory effects of green tea catechin on the lipid accumulation in 3T3-L1 adipocytes.

The aim of the present study was to evaluate the effects of green tea (‐)‐epigallocatechin‐3‐gallate (EGCG) on the depletion of accumulated fat in differentiated 3T3‐L1 adipocytes. Intracellular lipid accumulation was decreased significantly after 24 h of incubation with 10 µm EGCG, while the viability of adipocytes was reported to be unaffected. Under the same experimental conditions, the amount of glycerol released from cells into the medium was increased by 10 µm EGCG. The level of mRNA in the 3T3‐L1 adipocytes was analysed by quantitative real‐time RT‐PCR. EGCG notably increased the mRNA level of hormone sensitive lipase (HSL), which catalyses the rate‐limiting stage in hydrolysis of stored triacylglycerol to monoacylglycerol and free fatty acids. In conclusion, the experiment produced results which showed that green tea EGCG effectively depleted fat accumulation via the stimulation of lipolysis and increased HSL gene expression in 3T3‐L1 adipocytes. These results may relate to the mechanism by which EGCG modulates lipolysis in adipocytes. Copyright

Effects of Capsaicin on Lipid Catabolism in 3T3-L1 Adipocytes

Capsaicin (8‐methyl‐N‐vanillyl‐6‐nonenamide) is a pungent ingredient of red peppers, and has been reported to reduce body weight gain and adiposity in rodents. The present study investigated the effects of capsaicin on lipid catabolism in differentiated 3T3‐L1 adipocytes. Capsaicin decreased the intracellular lipid content in a concentration‐dependent manner. The release of glycerol into the medium was increased by the addition of capsaicin. The mRNA levels of genes involved in lipid catabolism such as hormone sensitive lipase (HSL), carnitine palmitoyl transferase‐Iα (CPTI‐α) and uncoupling protein 2 (UCP2) were up‐regulated significantly. These results suggest that capsaicin exerts its lipolytic action by increasing the hydrolysis of triacylglycerol in adipocytes, and that these effects are mediated at least partially by regulation of the expression of multiple genes that are involved in the lipid catabolic pathway, such as HSL and CPT‐Iα, and those involved in thermogenesis such as UCP2. Copyright

Ginsenoside RG3 reduces lipid accumulation with AMP-activated protein kinase (AMPK) activation in HepG2 cells

Cardiovascular disease (CVD) is one of the main causes of mortality worldwide, and dyslipidemia is a major risk factor for CVD. Ginseng has been widely used in the clinic to treat CVD. Ginsenoside Rg3, one of the major active components of ginseng, has been reported to exhibit antiobesity, antidiabetic, and cardioprotective effects. However, the effect of ginsenoside Rg3 on hepatic lipid metabolism remains unclear. Therefore, we investigated whether ginsenoside Rg3 would regulate hepatic lipid metabolism with AMP-activated protein kinase (AMPK) activation in HepG2 cells. Ginsenoside Rg3 significantly reduced hepatic cholesterol and triglyceride levels. Furthermore, ginsenoside Rg3 inhibited expression of sterol regulatory element binding protein-2 (SREBP-2) and 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGCR). Ginsenoside Rg3 increased activity of AMPK, a major regulator of energy metabolism. These results suggest that ginsenoside Rg3 reduces hepatic lipid accumulation with inhibition of SREBP-2 and HMGCR expression and stimulation of AMPK activity in HepG2 cells. Therefore, ginsenoside Rg3 may be beneficial as a food ingredient to lower the risk of CVD by regulating dyslipidemia.

Reduction of Body Weight by Dietary Garlic Is Associated with an Increase in Uncoupling Protein mRNA Expression and Activation of AMP-Activated Protein Kinase in Diet-Induced Obese Mice

This study investigated the antiobesity effect of garlic in diet-induced obese mice. Male C57BL/6J mice were fed a high-fat diet (45% fat) for 8 wk to induce obesity. Subsequently, they were fed a high-fat control diet, high-fat diets supplemented with 2%, or 5% garlic (wt:wt) for another 7 wk. Dietary garlic reduced body weight and the mass of various white adipose tissue deposits and also ameliorated the high-fat diet-induced abnormal plasma and liver lipid profiles. Garlic supplementation significantly decreased the mRNA levels of adipogenic genes in white adipose tissues (WAT). However, consumption of garlic increased the expression of mRNA for uncoupling proteins in brown adipose tissue (BAT), liver, WAT, and skeletal muscle. Mice treated with garlic maintained a significantly higher body temperature than untreated mice during a 6-h, 4°C cold challenge and, notably, AMP-activated protein kinase (AMPK) activity was stimulated in BAT, liver, WAT, and skeletal muscle. These results suggest that the antiobesity effects of garlic were at least partially mediated via activation of AMPK, increased thermogenesis, and decreased expression of multiple genes involved in adipogenesis.

Rutin Increases Muscle Mitochondrial Biogenesis with AMPK Activation in High-Fat Diet-Induced Obese Rats

Decreased mitochondrial number and dysfunction in skeletal muscle are associated with obesity and the progression of obesity-associated metabolic disorders. The specific aim of the current study was to investigate the effects of rutin on mitochondrial biogenesis in skeletal muscle of high-fat diet-induced obese rats. Supplementation with rutin reduced body weight and adipose tissue mass, despite equivalent energy intake (p < 0.05). Rutin significantly increased mitochondrial size and mitochondrial DNA (mtDNA) content as well as gene expression related to mitochondrial biogenesis, such as peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factor-1 (NRF-1), transcription factor A (Tfam), and nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, sirtulin1 (SIRT1) in skeletal muscle (p < 0.05). Moreover, rutin consumption increased muscle adenosine monophosphate-activated protein kinase (AMPK) activity by 40% (p < 0.05). Taken together, these results suggested at least partial involvement of muscle mitochondria and AMPK activation in the rutin-mediated beneficial effect on obesity.

Effects of Eicosapentaenoic Acid and Docosahexaenoic Acid on Uncoupling Protein 3 Gene Expression in C2C12 Muscle Cells

Uncoupling protein 3 (UCP3) is a mitochondrial membrane transporter that is expressed mainly in skeletal muscle where it plays an important role in energy expenditure and fat oxidation. In this study, we investigated the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on UCP3 gene expression in C2C12 muscle cells. EPA and DHA up-regulated UCP3 mRNA level in a dose-dependent manner and similarly increased UCP3 promoter activity in C2C12 muscle cells. To determine whether AMP-activated protein kinase (AMPK) signaling may also directly regulate UCP3 expression, 5′-amino-4-imidazolecarboxamide-ribonucleoside (AICAR), an AMP analog that activates AMPK, was treated in C2C12 muscle cells. AICAR showed additive effects with EPA or DHA on the UCP3 promoter activation. These results indicate that EPA and DHA directly regulate the gene expression of UCP3, potentially through AMPK-mediated pathway in C2C12 muscle cells.

Anti-obesity efficacy of nanoemulsion oleoresin capsicum in obese rats fed a high-fat diet.

Purpose This study determined the effects of oleoresin capsicum (OC) and nanoemulsion OC (NOC) on obesity in obese rats fed a high-fat diet. Methods The rats were randomly separated into three groups: a high-fat (HF) diet group, HF + OC diet group, and HF + NOC diet group. All groups were fed the diet and water ad libitum for 14 weeks. Results NOC reduced the body weight and adipose tissue mass, whereas OC did not. OC and NOC reduced mRNA levels of adipogenic genes, including peroxisome proliferator-activated receptor (PPAR)-γ, sterol regulatory element-binding protein-1c, and fatty acid-binding protein in white adipose tissue. The mRNA levels of genes related to β-oxidation or thermogenesis including PPAR-α, palmitoyltransferase-1α, and uncoupling protein-2 were increased by the OC and NOC relative to the HF group. Both OC and NOC clearly stimulated AMP-activated protein kinase (AMPK) activity. In particular, PPAR-α, palmitoyltransferase-1α, uncoupling protein-2 expression, and AMPK activity were significantly increased in the NOC group compared to in the OC group. NOC decreased glycerol-3-phosphate dehydrogenase activity whereas OC did not. Conclusion From these results, NOC could be suggested as a potential anti-obesity agent in obese rats fed a HF diet. The effects of the NOC on obesity were associated with changes of multiple gene expression, activation of AMPK, and inhibition of glycerol-3-phosphate dehydrogenase in white adipose tissue.

High Hydrostatic Pressure Extract of Red Ginseng Attenuates Inflammation in Rats with High-fat Diet Induced Obesity

Chronic low-grade inflammation is associated with obesity. This study investigated effect of high hydrostatic pressure extract of red ginseng (HRG) on inflammation in rats with high-fat (HF) diet induced obesity. Male, Sprague-Dawley rats (80~110 g) were randomly divided into two groups, and fed a 45% HF diet (HF) and a 45% HF diet containing 1.5% HRG (HF+HRG) for 14 weeks. At the end of the experiment, the serum leptin level was reduced by the HRG supplementation. The mRNA expression of genes related to adipogenesis including peroxisome proliferator-activated receptor-gamma and adipocyte protein 2 was down-regulated in the white adipose tissue (WAT). The mRNA levels of major inflammatory cytokines such as tumor necrosis factor-α, monocyte chemoattractant protein 1, and interleukin-6 were remarkably down-regulated by the HRG in WAT. These results suggest that HRG might be beneficial in ameliorating the inflammation-associated health complications by suppressing adipogenic and pro-inflammatory gene expression.

Effect of high hydrostatic pressure extract of fresh ginseng on adipogenesis in 3T3‐L1 adipocytes

BACKGROUND Red ginseng is produced by steaming and drying fresh ginseng. Through this processing, chemical compounds are modified, and then biological activities are changed. In the food-processing industry, high hydrostatic pressure (HHP) has become an alternative to heat processing to make maximum use of bioactive compounds in food materials. This study comparatively investigated the anti-adipogenic effects of water extract of red ginseng (WRG) and high hydrostatic pressure extract of fresh ginseng (HPG) in 3T3-L1 adipocytes. RESULTS Both WRG and HPG inhibited the accumulation of intracellular lipids and triglycerides, and the activity of glycerol-3-phosphate dehydrogenase (GPDH), a key enzyme in triglyceride biosynthesis. Intracellular lipid content and GPDH activity were significantly lower in the HPG group compared to the WRG group. In addition, mRNA expression of adipogenic genes, including CEBP-α, SREBP-1c and aP2, were lower in HPG-treated cells compared to WRG-treated cells. HPG significantly increased the activity of AMPK, and WRG did not. CONCLUSION Results suggested that HPG may have superior beneficial effects on the inhibition of adipogenesis compared with WRG. The anti-adipogenic effects of HPG were partially associated with the inhibition of GPDH activity, suppression of adipogenic gene expression and activation of AMPK in 3T3-L1 adipocytes.

Effects of Korean Red Ginseng extract on hepatic lipid accumulation in HepG2 cells

In this study, we investigated the effects of Korean red ginseng water extract (KRGE) on hepatic lipid accumulation in HepG2 cells. KRGE decreased hepatic triglyceride and cholesterol levels. Further, KRGE suppressed expression of fatty acid synthase (FAS) and 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase. These results suggest that KRGE may reduce hepatic lipid accumulation by inhibition of FAS and HMG-CoA reductase expression in HepG2 cells.