• Journal of Nutrition and Health
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• v.55 no.1
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• pp.36-46
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• 2022

Purpose: Quercetin is a polyphenolic flavonoid abundant in many fruits and vegetables. It has potential health-beneficial properties, such as antioxidant, anti-obesity, anti-cancer, anti-diabetic and anti-inflammatory effects. The purpose of this study was to investigate whether the lipid metabolism improvement effect of quercetin affected the regulation of AMP-activated protein kinase (AMPK) activity and microRNA (miR)-21 expression in the liver of mice fed a high-cholesterol diet. Methods: Male C57BL/6J mice were fed with normal diet, quercetin-free diet and diets containing 0.05% or 0.1% quercetin for six weeks. Hypercholesterolemia was induced by adding 1% cholesterol and 0.5% cholic acid to all diets. Serum and liver triglyceride (TG), and total cholesterol (TC) concentrations were analyzed using a commercial enzymatic colorimetric kit. AMPK activity was quantified using an AMPK kinase assay kit. The levels of miR-21 and genes involved in lipid metabolism were measured by real-time quantitative polymerase chain reaction. Results: Supplementation of quercetin reduced serum and hepatic TG and TC levels without changing body weight and food intake. Dietary quercetin significantly inhibited the mRNA levels of hepatic sterol-regulatory element binding protein-1c, acetyl-CoA carboxylase 1 and fatty acid synthesis, which are involved in hepatic lipogenesis. Dietary quercetin enhanced AMPK activity and suppressed miR-21 expression, promoting hepatic lipid accumulation. Conclusion: These results suggest that the lipid-lowering effect of quercetin on the serum and liver of mice may be partially mediated by the regulation of lipogenic gene expression, AMPK activity and miR-21 expression in the liver of mice fed a high-cholesterol diet.

• Korean Journal of Food Science and Technology
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• v.46 no.6
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• pp.762-768
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• 2014

In this study, the ameliorating effects of lactic acid-fermented garlic extract (LAFGE) on non-alcoholic fatty liver were investigated using oleic acid-induced steatotic HepG2 cells. The ameliorating mechanism was analyzed by RT-PCR and Western blot. Treatment with 1 mg/mL LAFGE decreased intracellular lipid accumulation approximately 1.5-fold, compared to that achieved with non-fermented garlic extract. LAFGE reduced fatty acid influx into hepatocytes through down-regulation of FAT/CD36 mRNA expression in the steatotic HepG2 cells. $PPAR{\alpha}$ and CPT-1 mRNA expression was significantly up-regulated by LAFGE treatment of HepG2 cells as a consequence of activation of beta oxidation. Additionally, the treatment with 1 mg/mL LAFGE highly down-regulated mRNA expression of SREBP-1c and FAS to 51% and 35%, respectively. LAFGE showed concentration-dependent down-regulation patterns in protein expression of SREBP-1c and FAS, as determined by Western blot. These results suggest that LAFGE treatment improves hepatic steatosis triggered by the imbalance of hepatic lipid metabolism owing to oleic acid treatment.

• Journal of Life Science
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• v.24 no.11
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• pp.1224-1230
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• 2014

The red radish (Raphanus sativus L.; RR) sprout is a plant of the cruciferous family. In this study, we elucidated the effect of the water extract of RR sprout (RRSE) against ${\alpha}$-amylase, ${\alpha}$-glucosidase, and pancreatic lipase enzyme activity and adipogenesis in 3T3-L1 preadipocytes. ${\alpha}$-amylase, ${\alpha}$-glucosidase, and pancreatic lipase enzyme activity was inhibited in a concentration-dependent manner by RRSE treatment. RSSE also abolished adipocyte differentiation and lipid and triglyceride accumulation without cytotoxicity in 3T3-L1 adipocytes. In addition, RRSE modulated the expression of the proteins related to adipogenic transcription factors: peroxisome proliferator-activated receptor (PPAR)${\gamma}$, sterol regulatory element-binding protein 1 (SREBP-1), and CCAT/enhancer binding protein (C/EBP)${\alpha}$. RRSE also suppressed expression of the proteins responsible for lipid synthesis, transport, and storage: adiponectin, fatty acid synthesis (FAS), perilipin, and fatty acid bind protein-4 (FABP4). This study showed that RRS treatment has the potential to inhibit obesity by controlling the expression of adipogenic transcription factors and adipogenic proteins.

• The Journal of Internal Korean Medicine
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• v.35 no.2
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• pp.175-183
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• 2014

Objectives : We tried to uncover the anti-lipogenic effect and underlying mechanism of Laminaria japonica on an experimental cellular model of non-alcoholic fatty liver disease. Methods : Ethanol extract of Laminaria japonica (LJ) was prepared. Intracellular lipid content of palmitate-treated HepG2 cells was evaluated with or without LJ treatment. We measured the effects of LJ on liver X receptor ${\alpha}$ ($LXR{\alpha}$) and sterol regulatory element-binding transcription factor-1c (SREBP-1c) expression, transcription level of lipogenic genes, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD-1), and nuclear factor erythroid 2-related factor 2 (Nrf2) activation in HepG2 cells. Results : LJ markedly attenuated palmitate-induced intracellular lipid accumulation in HepG2 cells. LJ suppressed $LXR{\alpha}$-dependent SREBP-1c activation, and SREBP-1c mediated induction of ACC, FAS, and SCD-1. Furthermore, LJ activated Nrf2, which plays an important cytoprotective role in non-alcoholic fatty liver disease. Conclusions : Our study suggests that LJ has the potential to alleviate hepatic lipid accumulation, and this effect was mediated by inhibiting the $LXR{\alpha}$-SREBP-1c pathway that leads to hepatic steatosis. In addition, the anti-lipogenic potential may, at least in part, be associated with activation of Nrf2.

• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.6
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• pp.802-808
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• 2013

Here we tried to uncover the potential anti-lipogenic effect and the underlying mechanism of Phaseolus angularis seed in a cellular model of nonalcoholic fatty liver disease (NAFLD) induced in HepG2 cells. Ethanol extract of Phaseolus angularis seed (JSD) was prepared. HepG2 cells were incubated in palmitate containing media to induce intracellular lipid accumulation, and co-treated with JSD for 16 hrs before examine intracellular lipid content. In control group, the cells were not co-treated with JSD. We measured the effects of JSD on liver X receptor ${\alpha}$ ($LXR{\alpha}$) and sterol regulatory element-binding transcription factor-1c (SREBP-1c) expression, transcription level of lipogenic genes, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD-1), and AMP-activated protein kinase (AMPK) activation in HepG2 cells. JSD markedly reduced palmitate-induced intracellular lipid accumulation in HepG2 cells. JSD suppressed $LXR{\alpha}$/SREBP-1c expression, and SREBP-1c mediated induction of ACC, FAS, and SCD-1. Furthermore, JSD activated AMPK, which plays a major role in the control of hepatic lipid metabolism. Taken together, it is suggested that JSD has a potential to alleviate hepatic steatosis, at least in part, by suppressing $LXR{\alpha}$/SREBP-1c mediated induction of lipogenic genes. In addtion, the anti-lipogenic potential may be associated with activation of AMPK. Therefore, the Phaseolus angularis seed could be applied as a potential therapeutics for NAFLD with additional clinical studies.

• Journal of Life Science
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• v.23 no.4
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• pp.518-528
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• 2013

Scutellaria baicalensis, belonging to the family Labiatae, is widely distributed in Korea, China, Mongolia, and eastern Siberia. It has been used in traditional medicine for various diseases, such as dysentery, pyrexia, jaundice, and carbuncles. In addition, S. baicalensis is reported to possess various beneficial pharmacological activities, including anti-inflammatory, antidiabetic, antiviral, antihypertension, antioxidant, and anticancer effects. However, the molecular mechanisms of its anticancer activity have not been clearly elucidated. In the present study, we investigated the proapoptotic effects of ethanol extract of S. baicalensis (EESB) on human renal cell carcinoma Caki-1 cells. The anti-proliferative activity of EESB was associated with apoptosis induction, which was associated with the up-regulation of death receptor 4, the Fas ligand, and Bax and the down-regulation of Bid, XIAP, and cIAP-1 proteins. EESB treatment also induced mitochondrial dysfunction, proteolytic activation of caspase-3, -8, and -9 and degradation of caspase-3 substrate proteins, such as poly (ADP-ribose) polymerase, ${\beta}$-catenin, and phospholipase C-${\gamma}1$. However, pretreatment of a pan-caspase inhibitor, z-VAD-fmk, significantly attenuated the EESB-induced apoptosis. Taken together, these findings suggest that EESB may be a potential chemotherapeutic agent. Further studies will be needed to identify the active compounds that confer the anticancer activity of S. baicalensis.

• Nutrition Research and Practice
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• v.12 no.6
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• pp.494-502
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• 2018

BACKGROUND/OBJECTIVES: Reducing the number of adipocytes by inducing apoptosis of mature adipocytes as well as suppressing differentiation of preadipocytes plays an important role in preventing obesity. This study examines the anti-adipogenic and pro-apoptotic effect of red pepper seed water extract (RPS) prepared at $4^{\circ}C$ (RPS4) in 3T3-L1 cells. MATERIALS/METHODS: Effect of RPS4 or its fractions on lipid accumulation was determined in 3T3-L1 cells using oil red O (ORO) staining. The expressions of AMP-activated protein kinase (AMPK) and adipogenic associated proteins [peroxisome proliferator-activated receptor-${\gamma}$ ($PPAR-{\gamma}$), CCAAT/enhancer-binding proteins ${\alpha}$ (C/EBP ${\alpha}$), sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC)] were measured in 3T3-L1 cells treated with RPS4. Apoptosis and the expression of Akt and Bcl-2 family proteins [B-cell lymphoma 2 (Bcl-2), Bcl-2-associated death promoter (Bad), Bcl-2 like protein 4 (Bax), Bal-2 homologous antagonist/killer (Bak)] were measured in mature 3T3-L1 cells treated with RPS4. RESULTS: Treatment of RPS4 ($0-75{\mu}g/mL$) or its fractions ($0-50{\mu}g/mL$) for 24 h did not have an apparent cytotoxicity on pre and mature 3T3-L1 cells. RPS4 significantly suppressed differentiation and cellular lipid accumulation by increasing the phosphorylation of AMPK and reducing the expression of $PPAR-{\gamma}$, C/EBP ${\alpha}$, SREBP-1c, FAS, and ACC. In addition, all fractions except ethyl acetate fraction significantly suppressed cellular lipid accumulation. RPS4 induced the apoptosis of mature adipocytes by hypophosphorylating Akt, increasing the expression of the pro-apoptotic proteins, Bak, Bax, and Bad, and reducing the expression of the anti-apoptotic proteins, Bcl-2 and p-Bad. CONCLUSIONS: These finding suggest that RPS4 can reduce the numbers as well as the size of adipocytes and might useful for preventing and treating obesity.

• Biomolecules & Therapeutics
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• v.31 no.1
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• pp.73-81
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• 2023

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

• Journal of Life Science
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• v.33 no.12
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• pp.967-977
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• 2023

Rubus crataegifolius (RC) is a traditional Asian medicinal plant belonging to the Rosaceae family. The fruits of RC are known to prevent adult diseases through antioxidants. In this study, the effects of RC extract (RCex) on obesity and nonalcoholic fatty liver disease (NAFLD) were evaluated in animal models. Twenty-eight male C57BL/6J mice were induced to become obese for 8 weeks and then the extract was orally administered for 8 weeks. RCex reduced body weight, adipose tissue, liver weight. RCex improved biochemical biomarkers including lipid metabolism (alanine aminotransferase (ALT), aspartate aminotransferase (AST), plasma triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol). The activation of AMP-activated protein kinase (AMPK) reduced the expression of adipogenesis genes (liver × receptor (LXR), sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthesis (FAS), acetyl-CoA carboxylase 1 (ACC1) and the effect of enhancing carnitine palmitoyltransferase (CPT) activity by RCex was verified. RCex also influence on plasma production of hormones (adiponectin & leptin) related on energy expenditure and metabolism. In addition, we confirmed that RCex improved glucose intolerance in HFD-induced obese rats. RCex was first demonstrated to have anti-obesity as well as anti-NAFLD effects by regulating fatty acid oxidation and fatty acid synthesis by phosphorylation of AMPK. This suggests that RCex could be a good supplement for the prevention of obesity and related NAFLD.

• Journal of Life Science
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• v.29 no.10
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• pp.1144-1151
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• 2019

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease associated with various metabolic syndromes, such as obesity, dyslipidemia, hypertension, and diabetes. Cudrania tricuspidata is a medicinal plant distributed widely in Asia and has been used in clinical practice to treat various diseases. The aim of this study is to determine the lipid-lowering effects of C. tricuspidata fruit extract (CTE) using a cell model induced by free fatty acids (FFAs). HepG2 cells were exposed to 1mM FFAs (palmitic acid:oleic acid = 2:1) for 24 hr to simulate the conditions of NAFLD in vitro. CTE attenuated the increases of lipid accumulation, intracellular triglyceride, and cholesterol content and inhibited 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) activity in the HepG2 cells in a dose-dependent manner. Also, CTE inhibited the protein expression of lipogenesis-related genes, such as sterol regulatory element-binding protein-1/-2 (SREBP-1/-2), fatty acid synthase (FAS), and stearoyl CoA desaturase-1 (SCD-1) in FFAs-induced lipid accumulation in HepG2 cells. In addition, CTE-induced adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in HepG2 cells. These results suggest that CTE attenuates hepatic lipid accumulation by inhibiting lipogenesis through the modulation of the AMPK signaling pathway on FFAs-induced lipogenesis in HepG2 cells and may potentially prevent NAFLD.