Yunkyung Han

Dongguk University, Sŏul, Seoul, South Korea

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Publications (7)7.01 Total impact

  • Yunkyung Han, Hyo Won Jung, Yong-Ki Park
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    ABSTRACT: The aim of the present study was to identify the selective therapeutic effects of Corni Fructus (Cornus officinalis Sieb. et Zucc.) on different organs in streptozotocin (STZ)-induced diabetic rats. Diabetes in rats was induced by intraperitonal injection with STZ at a dose of 30 mg/kg body weight (bw) for 3 days (once per a day). STZ-induced diabetic rats were orally administrated Corni Fructus (CF) extract at 300 mg/kg or metformin at 250 mg/kg daily for 4 weeks. Blood glucose and triglyceride (TG) in sera and urine total volume were measured. Histopathological changes of different organs, pancreas, liver, kidney, and lung tissues were observed by H&E staining. The expression of insulin and α-smooth muscle actin (α-SMA) was investigated in pancreas, and kidney by immunohistochemistry, respectively. The results revealed that CF extract significantly decreased the serum levels of blood glucose, and TG, and also urine total volume in STZ-induced diabetic rats. The histological examinations revealed amelioration of diabetes-induced pancreas injury including pathological changes of the Langerhans's islet and glomerular with their loss after the administration of CF extraction. Moreover, the administration of CF extract increased the numbers of insulin releasing beta cells in pancreas and also inhibited the expression of α-SMA in kidney of STZ-induced diabetic rats. On the other hand, CF extract showed no effect on the pathological damages of liver and lung in STZ-induced diabetic rats. These results demonstrated that CF extract may have a selective therapeutic potential through the control of hyperglycemia, and the protection of pancreas and kidney against diabetic damage.
    The American journal of Chinese medicine. 08/2014;
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    ABSTRACT: Liriope platyphylla has been reported to possess various biological activities, including anti-asthma, anti-inflammation, anti-diabetes, and neuriotogenic properties. In this study, we evaluated the effects of prosapogenin III isolated from the roots of L. platyphylla (Liriopis Tuber) on inflammatory responses in lipopolysaccharide (LPS) stimulated RAW264.7 mouse macrophages. We investigated LPS-induced production/expression of inflammatory mediators such as nitric oxide (NO), inducible nitric oxide synthase (iNOS), cyclooxigenase-2 (COX-2), and proinflammatory cytokines, including interleukin-1β (IL-1β) and interleukin (IL)-6 in RAW264.7 cells. We also performed Western blot analysis for determination of the phosphorylation of mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK) 1/2, p38, and c-Jun N-terminal kinase (JNK), and nuclear translocation of nuclear factor-κB (NF-κB) in LPS-stimulated cells. Treatment with prosapogenin III resulted in significant inhibition of NO production in LPS-stimulated Raw264.7 cells through suppression of iNOS expression. Treatment with prosapogenin III resulted in a significant decrease in expressions of COX-2, IL-1β, and IL-6 through down-regulation of their mRNA or protein in LPS-stimulated cells. In addition, treatment with prosapogenin III resulted in potently inhibited phosphorylation of three MAPKs, including ERK1/2, p38, and JNK in LPS-stimulated cells. Treatment with prosapogenin III also resulted in suppression of the nuclear translocation of NF-κB in LPS-stimulated cells. These results indicate that prosapogenin III of Liriopis Tuber has anti-inflammatory effects in activated macrophages through inhibition of production of inflammatory mediators by blockade of the MAPK/NF-κB pathway.
    Journal of Asian natural products research 08/2013; · 0.61 Impact Factor
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    ABSTRACT: Abstract Context: Obesity is associated with a number of diseases with metabolic abnormalities such as type 2 diabetes (T2D). Medicinal plants have been widely used for the treatment of obesity and related complications. Objective: In this study, we investigated the antidiabetic properties of the extract of twigs of Cinnamomum cassia Blume (Lauraceae) (Cinnamomi Ramulus; CR) in 3T3-L1 murine preadipocytes. Materials and methods: 3T3-L1 cells were differentiated into adipocytes for 3 d in insulin-conditioned medium and then treated with CR extract at concentrations of 100 and 500 μg/mL for 6 d. Adipocyte differentiation was measured by Oil Red O staining, and the expression of master transcription factors, peroxisome proliferator-activated receptor-gamma (PPARγ), CCAAT/enhancer binding protein-alpha (C/EBPα), and sterol regulatory element binding protein-1c (SREBP-1c), and lipid metabolism factors were investigated by reverse transcription-polymerase chain reaction (RT-PCR). The activation of the AMP-activated protein kinase (AMPK)/insulin signaling pathway was assessed by western blot analysis. Results: CR extract significantly reduced lipid accumulation and down-regulated the expression of PPARγ, C/EBPα, and SREBP-1c in 3T3-L1 adipocytes. CR extract also suppressed the expression of fatty acid synthase (FAS), acyl-CoA synthase, and perilipin. Moreover, CR extract markedly up-regulated the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC). In addition, CR extract effectively increased the expression levels of glucose transporter-4 (GLUT-4), phosphatidylinositol 3-kinase (PI3K), and insulin receptor substrate-1 (IRS-1) in 3T3-L1 adipocytes. Discussion and conclusion: These results suggest that CR extract may have therapeutic potential as a natural agent for the improvement of T2D via regulation of the insulin-dependent signaling pathway.
    Pharmaceutical Biology 04/2013; · 1.21 Impact Factor
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    Yunkyung Han, Yong-Ki Park
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    ABSTRACT: Objectives : This study aimed to compare the anti-diabetic efficacy of Lycii Radicis Cortex (Lycium chinense Mill.) and Corni Fructus (Cornus officinalis) on streptozotocin (STZ)-induced diabetes in rats. Methods : Male Sprague-Dawley rats were divided into four groups; normal, STZ-control, Lycii Radicis Cortex extract-administrated group (LRC) and Corni Fructus extract-administrated group(CF). Diabetes in rats was induced by intraperitonal injection with streptozotocin (STZ) at doses of, 30 mg/kg (body weight) for 5 days (once per a day). STZ-induced diabetic rats were orally administrated LRC and CF extract daily for 4 weeks at doses of 300 mg/kg. Fasting blood glucose, total cholesterol (TC), triglyceride (TG), blood urea nitrogen (BUN) and creatinine were measured in sera of rats. Histopathological changes of kidney, liver and lung tissues were observed by microscope after H&E staining. Results : There were no differences in body and kidney weights, food intake and water intake in LRC- and CF-administrated groups compared with STZ control group. However, glucose, TC and TG levels in serum were significantly decreased in LRC-administrated groups compared with STZ-control group. In histopathological analysis of kidney, liver and lung, both LRC- and CF-administrated groups showed the inhibition of morphological damage. Conclusions : These results suggest that LRC and CF have a biological action on STZ-induced diabetes in rats via decreasing the serum TG and TG levels and may protect the morphological changes of kidney, liver and lung.
    The Korea Journal of Herbology. 01/2013; 28(6).
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    ABSTRACT: The endoplasmic reticulum (ER) is an organelle that functions to synthesize, fold, and transport proteins. ER stress is a key link between type 2 diabetes (T2D), obesity, and insulin resistance. In this study, we investigated the effect of WHW on the ER stress response and the insulin signaling pathway in 3T3-L1 preadipocytes. 3T3-L1 preadipocytes were differentiated into adipocytes, and ER stress was then induced by treatment with tunicamycin. ER stress-induced adipocytes were treated with different concentrations of WHW for 24 h. The expression of ER stress-related molecules such as X-box-binding protein-1 (XBP-1), glucose-regulated protein 78 (GRP78), C/EBP-homologous protein 10 (CHOP10), and eukaryotic initiation factor 2 α (eIF2 α ) and signaling molecules such as phosphatidylinositol 3-kinase (PI3K), insulin receptor substrates-1 (IRS-1), and c-Jun N-terminal protein kinase (JNK) were investigated. WHW significantly inhibited the expression of XBP-1, GRP78, CHOP10, and eIF2 α in ER stress-induced 3T3-L1 adipocytes. WHW also increased the PI3K expression and the IRS-1 phosphorylation but decreased the phosphorylation of JNK in ER stress-induced 3T3-L1 adipocytes. Our results indicate that WHW inhibits ER stress in adipocytes by suppressing the expression of ER stress-mediated molecules and the insulin signaling pathway, suggesting that WHW may be an attractive therapeutic agent for managing T2D.
    Evidence-based Complementary and Alternative Medicine 01/2013; 2013:825814. · 1.72 Impact Factor
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    Yunkyung Han, Hyo Won Jung, Yong-Ki Park
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    ABSTRACT: BACKGROUND: Type 2 diabetes (T2D) is a complex metabolic disorder characterized by insulin resistance and hyperglycemia. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a key transcription factor and plays an important role in the regulation of genes involved in adipogenic differentiation, glucose metabolism and insulin signal transduction. METHODS: In this study, the effects of the root extract of Atractylodes japonica Koidzumi (Atractylodis Rhizoma Alba, ARA) on the differentiation of 3T3-L1 preadipocytes and the possible mechanism of glucose transport were investigated. 3T3-L1 cells were cultured with insulin and ARA extract. RESULTS: In 3T3-L1 cells, ARA extract significantly enhanced adipogenic differentiation and upregulated the expression of PPARgamma genes and protein in a dose-dependent manner. ARA also promoted glucose transport by increasing the glucose transporter 4 (GLUT-4), phosphatidylinositol 3-kinase (PI3K) and insulin receptor substrates-1 (IRS-1) levels. CONCLUSION: Our results suggest that ARA extract may be an attractive therapeutic agent for managing T2D via promoting the differentiation of adipocytes with the upregulation of PPARgamma levels and the activation of the insulin signaling pathway.
    BMC Complementary and Alternative Medicine 09/2012; 12(1):154. · 2.08 Impact Factor
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    ABSTRACT: Rehmanniae Radix Preparata, the steamed root of Rehmannia glutinosa Libosch, has been widely used for the treatment of inflammatory conditions in Oriental medicines. In this study we evaluated the effects of 2,5-dihydroxyacetophenone (DHAP) isolated from Rehmanniae Radix Preparata on inflammatory responses in lipopolysaccharide (LPS)-stimulated RAW264.7 mouse macrophages. LPS-stimulated RAW264.7 cells were used to investigate the anti-inflammatory activity of DHAP on the production of inflammatory mediators such as nitric oxide (NO), inducible NO synthase (iNOS), tumor necrosis factor-α (TNF-α), and interleukin (IL)-6. DHAP significantly inhibited NO production via the suppression of iNOS expression and significantly decreased levels of the pro-inflammatory cytokines TNF-α and IL-6 via the down-regulation of their mRNA expression in LPS-stimulated RAW264.7 cells. DHAP potently inhibited the phosphorylation of extracellular signal-related kinase (ERK) 1/2 and the nuclear translocation of nuclear factor-κB (NF-κB) p65 in LPS-stimulated cells. These results indicate that DHAP inhibits the production of inflammatory mediators in activated macrophages by blocking the ERK1/2 and NF-κB signaling pathways. Our results suggest that DHAP from Rehmanniae Radix Preparata has anti-inflammatory activity in activated macrophages, raising the possibility that this compound has a therapeutic potential for inflammatory conditions.
    Journal of medicinal food 04/2012; 15(6):505-10. · 1.39 Impact Factor