• Herbal Formula Science
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• v.29 no.2
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• pp.71-80
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• 2021

Objectives : This study investigated cellular-protective effects of Nardotidis seu Sulculii Concha water extract (NSCE) against oxidative stress induced by arachidonic acid (AA)+iron or tert-butylhydroperoxide (tBHP). Methods : In vitro, MTT assay was assessed for cell viability, and immunoblotting analysis was performed to detect expression of AMP-activated kinase (AMPK) signaling pathway and autophagy related proteins. In vivo, mice were orally administrated with the aqueous extract of NSCE of 500 mg/kg for 3 days, and then injected with CCl₄ 0.5 mg/kg body weight to induce acute damage. The level of liver damage was measured by serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) analysis. Results : Treatment with NSCE inhibited cell death induced by AA+iron and tBHP. NSCE induced the phosphorylation of AMPK, and this compound also induced the phosphorylation of LKB1, an upstream kinase of AMPK, and Acetyl-CoA carboxylase (ACC), a primary downstream target of AMPK. NSCE increased the protein levels of autophagic markers (LC3II and beclin-1) and decreased the phosphorylation of mammalian target of rapamycin (mTOR) and simultaneously increased the phosphorylation of unc-51-like kinase-1 (ULK-1) in time-dependent manner. Conclusions : NSCE has the ability 1) to protect cells against oxidative stress induced by AA+iron or tBHP. NSCE 2) to activate AMP-activated protein kinase (AMPK), and 3) to regulate autophagy, an important regulator in cell survival.

• Natural Product Sciences
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• v.26 no.3
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• pp.200-206
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• 2020

The ability of the total extract from Physalis angulata; three fractions after partitioning with n-hexane, ethyl acetate (TBE), and water; and four withanolides (compounds 1 - 4) to phosphorylate 5'-adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in HepG2 cells was evaluated. The TBE fraction (50 ㎍/mL) activated p-ACC and p-AMPK expression most strongly. Compounds 1 - 4 (10 μM) upregulated p-ACC expression at different levels. Compound 4 induced the most significant changes in p-AMPK expression, followed by 1 and 2. Sterol regulatory element-binding proteins (SREBPs) play a functional role in the transcriptional regulation of the lipogenic pathway, including fatty acid synthase (FAS) and ACC. The effects of compounds 2 and 4 (10 μM) on FAS and SREBP-1c expression under high glucose conditions (30 mM) in HepG2 cells were evaluated further. Both dose-dependently inhibited FAS and SREBP-1c expression as well as lipid accumulation (1 - 10 μM) were compared to high-concentration glucose control, which upregulated FAS and SREBP-1c. These results suggest that compounds 2 and 4 upregulate AMPK, suppress FAS and SREBP-1c, and have potential effects on glucose and lipid metabolism.

• Biomolecules & Therapeutics
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• v.32 no.2
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• pp.171-182
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• 2024

All cells are equipped with intricate signaling networks to meet the energy demands and respond to the nutrient availability in the body. AMP-activated protein kinase (AMPK) is among the most potent regulators of cellular energy balance. Under ATP -deprived conditions, AMPK phosphorylates substrates and affects various biological processes, such as lipid/glucose metabolism and protein synthesis. These actions further affect the cell growth, death, and functions, altering the cellular outcomes in energy-restricted environments. AMPK plays vital roles in maintaining good health. AMPK dysfunction is observed in various chronic diseases, making it a promising target for preventing and alleviating such diseases. Herein, we highlight the different AMPK functions, especially in allergy, aging, and cancer, to facilitate the development of new therapeutic approaches in the future.

• 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.

• Biomolecules & Therapeutics
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• v.24 no.6
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• pp.581-588
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• 2016

Lonchocarpine is a phenylpropanoid compound isolated from Abrus precatorius that has anti-bacterial, anti-inflammatory, antiproliferative, and antiepileptic activities. In the present study, we investigated the antioxidant effects of lonchocarpine in brain glial cells and analyzed its molecular mechanisms. We found that lonchocarpine suppressed reactive oxygen species (ROS) production and cell death in hydrogen peroxide-treated primary astrocytes. In addition, lonchocarpine increased the expression of anti-oxidant enzymes, such as heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), and manganese superoxide dismutase (MnSOD), which are all under the control of Nrf2/antioxidant response element (ARE) signaling. Further, mechanistic studies showed that lonchocarpine increases the nuclear translocation and DNA binding of Nrf2 to ARE as well as ARE-mediated transcriptional activities. Moreover, lonchocarpine increased the phosphorylation of AMP-activated protein kinase (AMPK) and three types of mitogen-activated protein kinases (MAPKs). By treating astrocytes with each signaling pathway-specific inhibitor, AMPK, c-jun N-terminal protein kinase (JNK), and p38 MAPK were identified to be involved in lonchocarpine-induced HO-1 expression and ARE-mediated transcriptional activities. Therefore, lonchocarpine may be a potential therapeutic agent for neurode-generative diseases that are associated with oxidative stress.

• Biomolecules & Therapeutics
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• v.25 no.6
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• pp.609-617
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• 2017

Pancreatic cancer is one of the most lethal and aggressive cancers in the world. However, no effective treatment is currently available for pancreatic cancer. The objective of this study was to determine the anti-pancreatic cancer effect of ${\alpha}$-mangostin (${\alpha}M$) and ${\gamma}$-mangostin (${\gamma}M$) extracted from the pericarp of Garcinia mangostana L.. Both ${\alpha}$M and ${\gamma}M$ reduced the viability of pancreatic cancer cells MIA PaCa-2 and PANC-1 in a dose-dependent manner. These compounds induced apoptosis by increasing c-PARP and c-Caspase 3 levels. They also induced autophagy by increasing levels of microtubule-associated protein 1A/1B light chain 3B (LC3II) in both cell lines while decreasing sequestosome 1 (p62) in MIA PaCa-2. Both ${\alpha}$M and ${\gamma}M$ induced autophagy through increasing phosphorylation levels of AMP-activated protein kinase (p-AMPK) and p38-mitogen activated protein kinase (p-p38) while decreasing phosphorylation level of mammalian target of rapamycin complex 1 (p-mTOR). Of various microRNAs (miRNA), miR-18a was found to be a putative regulatory miRNA for autophagy induced by ${\alpha}$M or ${\gamma}M$. In combination with gemcitabine, a compound frequently used in pancreatic cancer treatment, ${\alpha}$M and ${\gamma}M$ showed synergistic anti-cancer effects in MIA PaCa-2. Collectively, these results suggest that ${\alpha}$M and ${\gamma}M$ can induce apoptosis and autophagy in pancreatic cancer cells and that their anti-cancer effect is likely to be associated with miR-18a. In conclusion, ${\alpha}$M and ${\gamma}M$ might be used as a potential new therapy for pancreatic cancer.

• Journal of Animal Science and Technology
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• v.64 no.6
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• pp.1199-1214
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• 2022

Apolipoprotein H (APOH) primarily engages in fat metabolism and inflammatory disease response. This study aimed to investigate the effects of APOH on fat synthesis in duck myoblasts (CS2s) by APOH overexpression and knockdown. CS2s overexpressing APOH showed enhanced triglyceride (TG) and cholesterol (CHOL) contents and elevated the mRNA and protein expression of AKT serine/threonine kinase 1 (AKT1), ELOVL fatty acid elongase 6 (ELOVL6), and acetyl-CoA carboxylase 1 (ACC1) while reducing the expression of protein kinase AMP-activated catalytic subunit alpha 1 (AMPK), peroxisome proliferator activated receptor gamma (PPARG), acyl-CoA synthetase long chain family member 1 (ACSL1), and lipoprotein lipase (LPL). The results showed that knockdown of APOH in CS2s reduced the content of TG and CHOL, reduced the expression of ACC1, ELOVL6, and AKT1, and increased the gene and protein expression of PPARG, LPL, ACSL1, and AMPK. Our results showed that APOH affected lipid deposition in myoblasts by inhibiting fatty acid beta-oxidation and promoting fatty acid biosynthesis by regulating the expression of the AKT/AMPK pathway. This study provides the necessary basic information for the role of APOH in fat accumulation in duck myoblasts for the first time and enables researchers to study the genes related to fat deposition in meat ducks in a new direction.

• Journal of Life Science
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• v.32 no.2
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• pp.86-93
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• 2022

Lupeol is a type of pentacyclic triterpene and has been reported to have pharmacological activities against various diseases; however, the effect of lupeol on glucose absorption has not been elucidated yet. This study aimed to investigate the effect of lupeol on glucose uptake in 3T3-L1 adipocytes. Lupeol significantly facilitated glucose uptake by translocating glucose transporter type 4 (GLUT4) to the plasma membrane of the 3T3-L1 adipocytes, which was related to activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and 5 'adenosine monophosphate-activated protein kinase (AMPK) pathways. In the PI3K/AKT pathway, lupeol stimulates the phosphorylation of insulin receptor substrate 1 (IRS-1), which activates PI3K. Its activation by lupeol promotes the phosphorylation of AKT, but not the atypical protein kinase C isoforms ζ and λ. Lupeol also promoted the phosphorylation of AMPK. The activation of AMPK increased the expressions of the plasma membrane GLUT4 and the intracellular glucose uptake. The increase in the glucose uptake by lupeol was suppressed by wortmannin (PI3K inhibitor) and compound C (AMPK inhibitor) in the 3T3-L1 adipocytes. The results indicate that lupeol can facilitate glucose uptake by increasing insulin sensitivity through the stimulation of the expression of plasma membrane glucose transporter type 4 via the PI3K/AKT and AMPK pathways in the 3T3-L1 adipocytes.

• KSBB Journal
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• v.22 no.5
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• pp.341-344
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• 2007

Obesity is a major obstacle for human health, which induces various diseases such as cardiac injury and type 2 diabetes. Ginsenosides, active components of ginseng extract, exert various physiological effects. However, There are still no evidence for their anti obesity effects. In this study, we investigated the effects of ginsenoside Rd on adipocyte differentiation in 3T3-L1 cells. Our data show that ginsenoside Rd (80 uM) was effective in adipocyte differentiation inhibition. These inhibitory effects of ginsenosides on adipocyte differentiation were accompanied by PPAR gamma inhibition in rosiglitazone-treated cells. We also tested whether AMP-activated protein kinase (AMPK) activation was involved in the effects of these ginsenosides. AMPK is a master target for obesity, ginsenoside Rd significantly activated AMPK. Taken together, these results suggest that the anti obesity effects of ginsenoside Rd involve the AMPK signaling pathway and PPAR-gamma inhibition.

• Journal of Life Science
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• v.21 no.2
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• pp.251-256
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• 2011

EGCG, catechins in green tea, is a kind of phytochemical. Through the regulation of signal pathways, EGCG has been known to show anti-oxidant and anti-tumor effects in cells. In this study, we investigated the apoptotic effects of EGCG through AMP-activated protein kinase (AMPK) signal pathways, including hypoxia inducible factor-1 alpha (HIF-$1{\alpha}$). The experiments were performed in B16F10 melanoma cells in a hypoxic state. AMPK is activated by ATP consumption such as nutrient deficiency, exercise, heat shock, etc. The activated AMPK that plays an important role as an energy sensor inhibits proliferation of cancer cells, as well as inducing apoptosis. HIF-$1{\alpha}$, the primary transcriptional regulator of the response to oxygen deprivation, plays a critical role in modulating tumor growth and angiogenesis in a hypoxic state. The apoptotic effects of EGCG were studied in B16F10 cells in a hypoxic state. The results show that EGCG inhibits the transcriptional activity of HIF-$1{\alpha}$ and induces apoptosis. These observations suggest that EGCG may exert inhibitory effects of angiogenesis and control tumor cell growth in hypoxic melanoma cells.