• Journal of Life Science
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• v.33 no.11
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• pp.859-867
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• 2023

Lupeol is a type of pentacyclic triterpene that has been reported to have therapeutic effects for treating many diseases; however, its effect on insulin resistance is unclear clear. This study examined the inhibitory effect of lupeol on the serine phosphorylation of insulin receptor substrate-1 in insulin resistance-induced 3T3-L1 adipocytes. 3T3-L1 cells were cultured and treated with tumor necrosis factor-α (TNF-α) for 24 hours to induce insulin resistance. Cells treated with different concentrations of lupeol (15 μM or 30 μM) or 100 nM of rosiglitazone were incubated. Then, lysed cells underwent western blotting. Lupeol exhibited a positive effect on the negative regulator of insulin signaling and inflammation-activated protein kinase caused by TNF-α in adipocytes. Lupeol inhibited the activation of protein tyrosine phosphatase-1B (PTP-1B)-a negative regulator of insulin signaling-and c-Jun N-terminal kinase (JNK); it was also an inhibitor of nuclear factor kappa-B kinase (IKK) and inflammation-activated protein kinases. In addition, Lupeol downregulated serine phosphorylation and upregulated tyrosine phosphorylation in insulin receptor substrate-1. Then, the downregulated phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway was activated, the translocation of glucose transporter type 4 was stimulated to the cell membrane, and intracellular glucose uptake increased in the insulin resistance-induced 3T3-L1 adipocytes. Lupeol may improve TNF-α-induced insulin resistance by downregulating the serine phosphorylation of insulin receptor substrate 1 by inhibiting negative regulators of insulin signaling and inflammation-activated protein kinases in 3T3-L1 adipocytes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.2
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• pp.262-270
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• 2004

It is well known that long-term heavy ethanol intake causes alcoholic dementia, cerebellar degeneracy or Wernicke-Korsakoff syndrome and aggravates the conditions of many other neuro-psychotic disorders. Recently it is indicated that protein kinase C (PKC) plays an important role in the action of ethanol and in the neuro-adaptational mechanisms under chronic ethanol exposure. In order to investigate the effect of ethanol on PKC isoforms levels within the range of not showing any cytotoxicity, B103 neuroblastoma cell line trans-formed from murine central nervous system was employed and western blot analysis was carried out by using PKC isoform-specific antibodies. The changes of PKC-$\alpha$, ${\gamma}$, $\varepsilon$ and ζ level in the range of ethanol concentration 50∼200 mM were examined at the exposure time 1, 2, 8, 18 and 24 hrs in both cytosolic and membrane fraction. A typical ethanol concentration inducing the PKC isozymes was 100 mM, and the transforming time ranges of PKC isozymes could be considered as two different parts to each PKC isoform such as initial (0∼2 hrs) and prolonged (8∼24 hrs) stages. PKC-${\gamma}$ and PKC-$\varepsilon$ were clearly induced during the prolonged stages in cytosol at 18 hrs, and membrane fraction at 8 hrs and 18 hrs, respectively. On the other hand the PKC-$\alpha$ and PKC-ζ isozymes were largely induced in the prolonged stages at 18 hrs and 24 hrs, where the PKC-$\alpha$ isozyme was induced in both cytosol and membrane fractions at 200 mM ethanol concentration while the PKC-ζ isozyme was induced only in the membrane fractions at 100,200 mM. At 200 mM ethanol concentration of 24 hrs incubation in the prolonged stage, the PKC-$\alpha$ was maximally induced by 150% of the control values whereas the PKC-${\gamma}$ was significantly decreased to 47% of the control values. These results suggest that 100∼200 mM ethanol may modulate the signal transduction and neurotransmitter release in the central nervous system through the regulation of PKC isozymes, and the action of these isoforms may act differently each other in the cell.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.581-585
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• 2005

Five lactic acid bacteria (LAB) including 2 Lactobacillus strains isolated from Kimchi were evaluated to determine the binding ability to Caco-2 cells and $AFB_1$. LAB were divided into three different groups ; viable, heat-treated, and acid-treated cells. In the radioactive-labeling assay for bound cell counting, viable Lactobacillus Plantarum KCTC 3099 showed the higher adhesion to Caco-2 cells with the binding capacity of $39.2\%$, which was $149\%$ higher than Lactobacillus rhamnosus GG as a positive control. Leuconostoc mesenteroids KCTC 3100 showed the similar binding ability to L. rhamnosus GG. After 1 hour incubation at $37^{\circ}C$ with $AFB_1$, viable L. Planterum KTCC 3099 removed the toxin by $49.8\%$, which was similar level to L. rhamnosus GG. Both heat- and acid-treated groups showed high binding effect but acid-treated group was more effective for both Caco-2 cell binding and $AFB_1$ removal than the other. These results indicate that components of bacterial cell wall might be involved in tile binding to intestinal cells and toxins.

• Journal of Life Science
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• v.31 no.1
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• pp.1-9
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• 2021

Brown seaweeds have been shown to decrease blood glucose levels and improve insulin sensitivity previously. In this study, we investigated the effect of fucoidan, a complex polysaccharide derived from brown seaweeds, on glucose uptake to improve insulin resistance, and examined its mechanism of action in 3T3-L1 adipocytes. We observed that fucoidan significantly increased glucose uptake and it was related to an increased expression of plasma membrane-glucose transporter 4 (PM-GLUT4) in 3T3-L1 adipocytes. Fucoidan treatment increased the activation of phosphatidylinositol-3-kinase (PI3K) and the phosphorylation of insulin receptor substrate 1 (IRS1tyr) compared with that of the control cells. Fucoidan also promoted the phosphorylation of Akt and protein kinase C (PKC)-λ/ζ compared to that of the control cells. Moreover, fucoidan significantly upregulated acetyl-CoA-carboxylase (ACC) and adenosine monophosphate - activated protein kinase (AMPK) phosphorylation. As a result, translocation of GLUT4 was significantly enhanced in 3T3-L1 adipocytes, which significantly promoted glucose uptake via the PI3K/AMPK pathways. The elevation of glucose uptake by fucoidan was blocked by inhibitor of PI3K and inhibitor of AMPK in 3T3-L1 adipocytes. These findings indicate that fucoidan might ameliorate glucose uptake through GLUT4 translocation to the plasma membrane by activating the PI3K/Akt and AMPK pathways in 3T3-L1 adipocytes. Fucoidan is thought to be of high material value to diabetes treatments and functional foods.

• The Korean Journal of Food And Nutrition
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• v.23 no.1
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• pp.30-38
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• 2010

This study was conducted to determine the effects of vitamin C on the activity of liver function enzymes and electromicrographic changes in white rats treated with aflatoxin $B_1(AFB_1)$ or X-ray and $AFB_1$. Six week-old male Sprague-Dawley rats were randomly divided into five groups: a control group, $AFB_1$ treated group, $AFB_1$ treated group with vitamin C, X-ray and $AFB_1$ co-treated group, X-ray and $AFB_1$ co-treated group with vitamin C. On the first day of the experiment, only one dose of X-rays was exposed to the entire liver at 1,500 cGy. Next, vitamin C was injected at 10 mg/kg body weight by intraperitoneal injection, followed 1 hr later by the administration of 0.4 mg/kg of $AFB_1$ by intraperitoneal injection. These treatments were then administered every three days over a period of 15 days. On the 16th day of treatments, the animals were sacrificed. Analysis of the activity of the liver function enzymes, GOT, ALK phatase and LDH, in the sera of rats revealed that they were somewhat increased by $AFB_1$ treatment, X-ray and $AFB_1$ co-treatment when compared to the control group. Furthermore, the activity of these enzymes decreased in response to administration of vitamin C. Especially, the levels of GOT were remarkably decreased in the $AFB_1$ treated group treated with vitamin C when compared to the group treated with $AFB_1$ alone(p<0.001). Electromicrographic analysis revealed cloudy swelling, necrosis, vesicular degeneration and fat accumulation of hepatocytes in response to treatment with $AFB_1$ or co-treatment with X-ray and $AFB_1$. However, the destruction of hepatic cells was considerably lower in the vitamin C-treated group. These results indicate that vitamin C had ameliorating effects on the hepatic cell damage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.9
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• pp.1257-1264
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• 2016

Extracts from Artemisia annua $Linn\acute{e}$ (AAE) have various functions (anti-malaria, anti-virus, and anti-oxidant). However, the mechanism of the effects of AAE is not well known. Thus, we determined the apoptotic effects of AAE in AGS human gastric carcinoma cells. In this study, we suggested that AAE may exert cancer cell apoptosis through the Akt/mammalian target of rapamycin (mTOR)/glycogen synthase kinase (GSK)-$3{\beta}$ signal pathway and mitochondria-mediated apoptotic proteins. Activation by Akt phosphorylation resulted in cell proliferation through phosphorylation of tuberous sclerosis complex 2 (TSC2), mTOR, and GSK-$3{\beta}$. Thus, de-phosphorylation of Akt inhibited cell proliferation and induced apoptosis through inhibition of Akt, mTOR, phosphorylation of GSK-$3{\beta}$ at serine9, and control of Bcl-2 family members. Inhibition of GSK-$3{\beta}$ attenuated loss of mitochondrial membrane potential and release of cytochrome C. Bax and pro-apoptotic proteins were activated by their translocation into mitochondria from the cytosol. Translocation of Bax induced outer membrane transmission and generated apoptosis through cytochrome C release and caspase activity. We also measured 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, lactate dehydrogenase assay, Hoechst 33342 staining, Annexin V-PI staining, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide staining, and Western blotting. Accordingly, our study showed that AAE treatment to AGS cells resulted in inhibition of Akt, TSC2, GSK-$3{\beta}$-phosphorylated, Bim, Bcl-2, and pro-caspase 3 as well as activation of Bax and Bak expression. These results indicate that AAE induced apoptosis via a mitochondrial event through regulation of the Akt/mTOR/GSK-$3{\beta}$ signaling pathways.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.1
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• pp.60-66
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• 2014

The aim of this study was to evaluate the antioxidant activity and protective effect of extracts from the stems and leaves of Chrysanthemum boreale (CBSL) on t-BHP induced oxidative stress in human liver cells (Chang cells). Antioxidant activities in the extracts were determined for various radical scavenging activities including ferric reducing antioxidant power, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity, and oxygen radical absorbance capacity (ORAC). CBSL showed a very good scavenging effect of DPPH radical ($IC_{50}$ $0.009{\pm}0.002$ mg/mL), alkyl radical ($IC_{50}$ $0.004{\pm}0.001$ mg/mL), and hydroxyl radical ($IC_{50}$ $6.742{\pm}0.152$ mg/mL). CBSL also showed a strong antioxidant effect in the ORAC assay. In the MTT assay on human liver cells (Chang cells), the extracts showed protective effects by increasing cell viability, decreasing ROS, and restoring mitochondria membrane potential upon t-BHP induced oxidative stress. Our findings suggest that CBSL extracts are a potential therapeutic with protective antioxidant effects upon oxidative stress.

• Journal of Nutrition and Health
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• v.30 no.6
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• pp.658-668
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• 1997

Path of a small hydrophobic molecule through the aqueous cytoplasma is not linear. Partition may favor membrane binding by several orders of magnitude : thus significant membrane association will markedly decrease the cytosolic transport rate. The presence of high concentration of soluble binding proteins for these hydrophobic molecules would compete with membrane association and thereby increase transport rate. For long chain fatty acid molecules, a family of cytosolic binding proteins collectively known as the fatty acid binding proteins(FABP), are thought to act as intracellular transport proteins. This paper examines the mechanism of transfer of fluorescent antyroyloxy-labeled fatty acids(AOFA) from purified FABPs to phosholipid membranes. With the exception of the liver FABP, AOFA is transferred from FABP by collisional interaction of the protein with a acceptor membrane. The rate of transfer increased markedly when membranes contain anionic phospholipids. This suggests that positively charged residues on the surface of the FABP may interact with the membranes. Neutralization of the surface lysine residues of adipocyte FABP decreased fatty acid transfer rate, and transfer was found to proceed via aqueous diffusion rather than collisional interaction. Site specific mutagenesis has further shown that the helix-turn-helix domain of the FABP is critical for interaction with anionic acceptor membranes. Thus cytosolic FABP may function in intracellular transport of fatty acid to decrease their membranes association as well as to target fatty acid to specific subcellular sites of utilization.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.8
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• pp.1328-1336
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• 2003

This study was done to investigate the effects of n-3, n-6 fatty acid and d-limonene on the hepatic membrane lipid composition, protein kinase C (PKC) and glutathione S-transferase (GST) activities in experimental rat hepatocarcinogenesis. Sprague-Dawley female rats were fed with two different types of dietary oil for 20 weeks. Corn oil (CO) and sardine oil (SO) were used at 15% by weight as a source of n-6 and n-3 fatty acid, respectively. One week after feeding, rats were intraperitoneally injected twice with a dose of diethylnitrosamine (DEN, 50 mg/kg body weight) and after 1 week 0.05% phenobarbital (PB) was provided with drinking water. Membrane fractional lipid composition showed that the content of cholesterol was higher in 50 group than CO group and also significantly decreased by d-limonene. The content of phospholipid was increased by carcinogen treatment but not affected by dietary oils or d-limonene. Membrane C/PL molar ratio was significantly decreased by d-limonene or carcinogen treatment in 50 groups but not in CO groups. Fatty acid composition was changed by dietary oils but not by carcinogen treatment or d-limonene. Cytosolic PKC activity was not significantly different by dietary oils, d-limonene or carcinogen treatment. However, membrane PKC activity was significantly increased by carcinogen treatment and decreased by d-limonene. Cytosolic GST activity was affected by d-limonene or carcinogen treatment in all dietary groups. These data indicate that dietary oils, d-limonene and carcinogen treatment can not change much membrane phospholipid composition. But membrane C/PL molar ratio was changed by carcinogen treatment and d -limonene although the effect was different between dietary oils. Therefore, it is suggested that different dietary oils and d-limonene can somewhat modulate the changes of membrane fluidity and activities of membrane bound enzymes like membrane associated PKC during carcinogenesis.

• Journal of Nutrition and Health
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• v.41 no.1
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• pp.22-30
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• 2008

This study analyzes the apoptosis of HeLa cells to see if we can use the Artemisia capillaris Thunberg for the prevention of chronic degenerative diseases. We used the HeLa cells to see what effects the A. capillaris Thunberg had on apoptosis of the cancer cells. We checked the cell activity, cell morphological change, DNA fragmentation, and DNA content after administering 0, 100, 500, 1000, and $2000{\mu}g/ml$ methanol, ethyl acetate, n-butanol extract of the A. capillaris Thunberg. As for the cell viability, the increase of concentration of methanol and ethyl acetate decreased the survival rate of the cell, but the phenomenon was much weakened in n-butanol extract and was not observed in aqueous extract. The higher the density of the methanol, ethyl acetate, n-butanol and aqueous extract was, the lower the survival rate of the HeLa cell was. These extracts obstructed the cell cohesion and caused the blebbing of he cell membrane and fragmentation of the nucleus, both of which are symptoms of apoptosis. Laddering-pattern DNA fragmentation was observed in the groups that were treated with the $1000{\mu}g/ml$ and $2000{\mu}g/ml$ of methanol extract. The DNA content of the cells apoptosis measured by fluorescent-activated cell sorter (FACS) increased as the density of the methanol, ethyl acetate and butanol extract increased. The result of the study shows that A. capillaris Thunberg fosters the apoptosis of HeLa cells, which suggests that the A. capillaris Thunberg has a great potential value as food additives, medicinal supplements for patients with chronic diseases, and preventive measures against cancer.