Ki Sung Kang

Ulsan University Hospital, Urusan, Ulsan, South Korea

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Publications (72)167.93 Total impact

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    ABSTRACT: Autophagy is a series of catabolic process mediating the bulk degradation of intracellular proteins and organelles through formation of a double-membrane vesicle, known as an autophagosome, and fusing with lysosome. Autophagy plays an important role of death-survival decisions in neuronal cells, which may influence to several neurodegenerative disorders including Parkinson's disease. Chebulagic acid, the major constituent of Terminalia chebula and Phyllanthus emblica, is a benzopyran tannin compound with various kinds of beneficial effects. This study was performed to investigate the autophagy enhancing effect of chebulagic acid on human neuroblastoma SH-SY5Y cell lines. We determined the effect of chebulagic acid on expression levels of autophago-some marker proteins such as, DOR/TP53INP2, Golgi-associated ATPase Enhancer of 16 kDa (GATE 16) and Light chain 3 II (LC3 II), as well as those of its upstream pathway proteins, AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and Beclin-1. All of those proteins were modulated by chebulagic acid treatment in a way of enhancing the autophagy. Additionally in our study, chebulagic acid also showed a protective effect against 1-methyl-4-phenylpyridinium (MPP(+)) - induced cytotoxicity which mimics the pathological symptom of Parkinson's disease. This effect seems partially mediated by enhanced autophagy which increased the degradation of aggregated or misfolded proteins from cells. This study suggests that chebulagic acid is an attractive candidate as an autophagy-enhancing agent and therefore, it may provide a promising strategy to prevent or cure the diseases caused by accumulation of abnormal proteins including Parkinson's disease.
    Biomolecules & therapeutics. 07/2014; 22(4):275-81.
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    ABSTRACT: The epithelial-mesenchymal transition (EMT) is a pivotal cellular process during which epithelial polarized cells become motile mesenchymal-appearing cells, which, in turn, promotes the metastatic potential of cancer. Ginseng is a perennial plant belonging to the genus Panax that exhibits a wide range of pharmacological and physiological activities. Ginsenosides 20-Rg3, which is the active component of ginseng, has various medical effects, such as anti-tumorigenic, anti-angiogenesis, and anti-fatiguing activities. In addition, ginsenosides 20(S)-Rg3 and 20(R)-Rg3 are epimers, and this epimerization is produced by steaming. However, the possible role of 20(S)-Rg3 and 20(R)-Rg3 in the EMT is unclear. We investigated the effect of 20(S)-Rg3 and 20(R)-Rg3 on the EMT. Transforming growth factor-beta 1 (TGF-β1) induces the EMT to promote lung adenocarcinoma migration, invasion, and anoikis resistance. To understand the repressive role of 20(S)-Rg3 and 20(R)-Rg3 in lung cancer migration, invasion, and anoikis resistance, we investigated the potential use of 20(S)-Rg3 and 20(R)-Rg3 as inhibitors of TGF-β1-induced EMT development in A549 lung cancer cells in vitro. Here, we show that 20(R)-Rg3, but not 20(S)-Rg3, markedly increased expression of the epithelial marker E-cadherin and repressed Snail upregulation and expression of the mesenchymal marker vimentin during initiation of the TGF-β1-induced EMT. 20(R)-Rg3 also inhibited the TGF-β1-induced increase in cell migration, invasion, and anoikis resistance of A549 lung cancer cells. Additionally, 20(R)-Rg3 markedly inhibited TGF-β1-regulated matrix metalloproteinase-2 and activation of Smad2 and p38 mitogen activated protein kinase. Taken together, our findings provide new evidence that 20(R)-Rg3 suppresses lung cancer migration, invasion, and anoikis resistance in vitro by inhibiting the TGF-β1-induced EMT.
    Toxicology 05/2014; · 4.02 Impact Factor
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    ABSTRACT: Anti-cancer effects were compared amongst Taraxacum coreanum extract, its fractions, and 7 ingredients (β-sitosterol, daucosterol, taraxasteryl acetate, chrysoeriol, diosmetin, luteolin, and luteoloside). Exposure to the ethyl acetate fraction (50 and 100 μg/mL) of T. coreanum extract and luteolin (10 and 50 μM) for 24 h induced the cleavage of poly (ADP-ribose) polymerase (PARP), caspase-3, and caspase-8, in a dose-dependent manner. These findings demonstrate that luteolin is the main active component of T. coreanum extract activating caspases-3 and -8 which contribute to apoptotic cell death.
    Journal of the Korean Society for Applied Biological Chemistry 04/2014; · 0.43 Impact Factor
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    ABSTRACT: Ginsenoside Re is a triol type triterpene glycoside and is abundantly present in ginseng berry. In the present study, we verified that ginsenoside Re can be transformed into less-polar ginsenosides, namely, Rg2, Rg6, and F4, by heat-processing. The products of heat-processed ginsenoside Re inhibited phosphorylation of CDK2 at Thr160 by upregulation of p21 level, resulting in S phase arrest. The products of heat-processed ginsenoside Re also activated caspase-8, caspase-9, and caspase-3, followed by cleavage of PARP, a substrate of caspase-3, in a dose-dependent manner. Concurrently, alteration of mitochondrial factors such as Bcl-2 and Bax was also observed. Moreover, pretreatment with Z-VAD-fmk abrogated caspase-8, -9, and -3 activations by the products of heat-processed ginsenoside Re. We further confirmed that the anticancer effects of the products of heat-processed ginsenoside Re in AGS cells are mainly mediated via generation of less-polar ginsenosides Rg6 and F4.
    Journal of Agricultural and Food Chemistry 03/2014; · 3.11 Impact Factor
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    ABSTRACT: Potassium arylethynyltrifluoroborates, the intermediates generated by the Sonogashira reaction of potassium ethynyltrifluoroborate with various aryl halides, were directly coupled with azides in the presence of a stoichiometric amount of CuI under aqueous conditions, and the desired 1,4-disubstituted 1,2,3-triazoles were isolated in good yields. Both electron-donating and electron-withdrawing substituents on the potassium arylethynyltrifluoroborates gave moderate to excellent yields of the isolated products.
    ChemInform 03/2014; 45(11).
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    ABSTRACT: The present study investigated the presence and mechanism of esculin-mediated renoprotection, to assess its therapeutic potential. Esculin was orally administered at 20 mg/kg/day for 2 weeks to streptozotocin-induced diabetic mice, and its effects were compared with those of the vehicle in normal and diabetic mice. After oral administration of esculin to mice, the concentrations of esculin and esculetin in blood were 159.529.8 ng/mL and 9.74.9 ng/mL at 30 min, respectively. Food and water intake were significantly increased in the diabetic mice compared to normal mice, but were attenuated in mice receiving esculin. The elevated blood glucose level and hepatic glucose-6-phosphatase expression were significantly reduced in esculin-treated diabetic mice, supporting the anti-diabetic effect of esculin. Esculin also increased the uptake of glucose and induced the insulin-evoked phosphorylation of insulin receptor, Akt, and glycogen synthase kinase 3β in C2C12 myotubes, indicating a potential for improvement of insulin sensitivity. In addition, esculin lessened the elevated blood creatinine levels in diabetic mice and ameliorated diabetes-induced renal dysfunction by reducing caspase-3 activation in the kidney. The data support the beneficial effect of esculin against diabetes and oxidative stress-related inflammatory processes in the kidney.
    Journal of Agricultural and Food Chemistry 01/2014; · 3.11 Impact Factor
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    ABSTRACT: The structural change of ginsenoside and the generation of Maillard reaction products (MRPs) are important to the increase in the biological activities of Panax ginseng. This study was carried out to identify the renoprotective active component of P. ginseng using the Maillard reaction model experiment with ginsenoside Re and leucine. Ginsenoside Re was gradually converted into less-polar ginsenosides Rg2, Rg6 and F4 by heat-processing, followed by separation of the glucosyl moiety at carbon-20. The free radical-scavenging activity of the ginsenoside Re-leucine mixture was increased by heat-processing. The improved free radical-scavenging activity by heat-processing was mediated by the generation of MRPs from the reaction of glucose and leucine. The cisplatin-induced LLC-PK1 renal cell damage was also significantly reduced by treatment with MRPs. Moreover, the heat-processed glucose-leucine mixture (major MRPs from the ginsenoside Re-leucine mixture) showed protective effects against cisplatin-induced oxidative renal damage in rats through the inhibition of caspase-3 activation.
    Food Chemistry 01/2014; 143:114-21. · 3.33 Impact Factor
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    ABSTRACT: Background Glucocorticoids (GCs) are commonly used in many chemotherapeutic protocols and play an important role in the normal regulation of bone remodeling. However, the prolonged use of GCs results in osteoporosis, which is partially due to apoptosis of osteoblasts and osteocytes. In this study, effects of Korean Red Ginseng (KRG) of a GC-treated murine osteoblastic MC3T3-E1 cells and a GC-induced osteoporosis mouse model were investigated. Methods MC3T3-E1 cells were exposed to dexamethasone (Dex) with or without KRG and cell viability was measured by MTT assay. Real-time PCR was done to evaluate the apoptotic gene expression, osteogenic gene expression and ALP activity were also measured. Western blotting was performed to evaluate the MAPK proteins. Glucocorticoid-induced osteoporosis animal model was used for in vivo study. Results and conclusion: MTT assay revealed that KRG prevents a loss of cell viability against dexamethasone (Dex) induced apoptosis in MC3T3E1 cells. Real-time polymerase chain reaction (PCR) data showed that groups treated with both Dex and KRG exhibited lower mRNA levels of caspase-3 and -9, whereas the mRNA levels of Bcl2, IAPs and XIAP increased. Moreover, groups treated with both Dex and KRG demonstrated increased mRNA levels of ALP, RUNX2, and BMPs as well as increased ALP activity in MC3T3-E1 cells compared to cells only treate with Dex. In addition, KRG increased AKT phosphorylation and decreased JNK phosphorylation. Also, Micro-CT analysis of the femurs showed that GC implantation caused trabecular bone loss. However, a significant reduction of bone loss was observed in the KRG-treated group. These results suggest that the molecular mechanism of KRG in the GC-induced apoptosis may lead to the development of therapeutic strategies to prevent and/or delay osteoporosis.
    Journal of ginseng research 01/2014; · 2.26 Impact Factor
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    ABSTRACT: Research has been conducted with regard to the development of methods for improving the pharmaceutical effect of ginseng by conversion of ginsenosides, which are the major active components of ginseng, via high temperature or high-pressure processing. The present study sought to investigate the anticancer effect of heat-processed American ginseng (HAG) in human gastric cancer AGS cells with a focus on assessing the role of apoptosis as an important mechanistic element in its anticancer actions. HAG significantly reduced the cancer cell proliferation, and the contents of ginsenosides Rb1 and Re were markedly decreased, whereas the peaks of less-polar ginsenosides [20(S,R)-Rg3, Rk1, and Rg5] were newly detected. Based on the activity-guided fractionation of HAG, ginsenoside 20(S)-Rg3 played a key role in inducing apoptosis in human gastric cancer AGS cells, and it was generated mainly from ginsenoside Rb1. Ginsenoside 20(S)-Rg3 induced apoptosis through activation of caspase-3, caspase-8, and caspase-9, as well as regulation of Bcl-2 and Bax expression. Taken together, these findings suggest that heat-processing serves as an increase in the antitumor activity of American ginseng in AGS cells, and ginsenoside 20(S)-Rg3, the active component produced by heat-processing, induces the activation of caspase-3, caspase-8, and caspase-9, which contributes to the apoptotic cell death.
    Journal of ginseng research 01/2014; 38(1):22-7. · 2.26 Impact Factor
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    ABSTRACT: Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors and expressed in various cell types in the skin, including keratinocytes, fibroblasts and infiltrating immune cells. Thus, their ligands are targets for the treatment of various skin disorders, such as photo-aging and chronological aging of skin. Intensive studies have revealed that PPARα/γ functions in photo-aging and age-related inflammation by regulating matrix metalloproteinases (MMPs) via activator protein-1 (AP-1) and nuclear factor kappa B (NF-κB). However, the detailed mechanism of PPARα/γ’s role in skin aging has not yet been elucidated. In this study, we confirmed that Sargahydroquinoic acid (SHQA) as a PPARα/γ ligand significantly decreased Tumor Necrosis Factor-alpha (TNFα)-induced MMP-2/-9 expression by downregulating TNFα-induced transcription factors, subsequently reducing IκBα degradation and blocking NF-κB p65 nuclear translocation in HaCaT human epidermal keratinocyte cells. Treatment of cells with SHQA and GW6471 (PPARα antagonist) not bisphenol A diglycidyl ether (PPARγ antagonists), reversed the effect on TNFα-induced inflammatory signaling pathway activation. Taken together, our data suggest that SHQA inhibit TNFα-induced MMP-2/-9 expression and age-related inflammation by suppressing AP-1 and NF-κB pathway via PPARα and is a useful agent for improving skin aging.
    Biochemical and Biophysical Research Communications 01/2014; · 2.28 Impact Factor
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    ABSTRACT: Neobavaisoflavone (NBIF), an isoflavone isolated from Psoralea corylifolia (Leguminosae), has striking anti-inflammatory and anti-cancer effects. NBIF inhibits the proliferation of prostate cancer in vitro and in vivo. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a key endogenous molecule that selectively induces apoptosis in cancer cells with little or no toxicity in normal cells. However, some cancer cells, including U373MG cells, are resistant to TRAIL-mediated apoptosis. We demonstrated that the cell viability, migration and invasion assay were used in U373MG glioma cells. In this study, we found that NBIF sensitizes human U373MG glioma cells to TRAIL-mediated apoptosis. Co-treatment of TRAIL and NBIF effectively induced Bid cleavage and activated caspases 3, 8, and 9. Importantly, DR5 expression was upregulated by NBIF. We also observed that the combination NBIF and TRAIL increased expression of BAX. We further demonstrate that NBIF induced TRAIL-mediated apoptosis in human glioma cells by suppressing migration and invasion, and by inhibiting anoikis resistance. Taken together, our results suggest that NBIF reduces the resistance of cancer cells to TRAIL and that the combination of NBIF and TRAIL may be a new therapeutic strategy for treating TRAIL-resistant glioma cells.
    Life sciences 11/2013; · 2.56 Impact Factor
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    ABSTRACT: Diabetic nephropathy is one of the serious complications in patients with either type 1 or 2 diabetes mellitus but current treatments remain unsatisfactory. Results of clinical research studies demonstrate that Panax ginseng can help adjust blood pressure and reduce blood sugar and may be advantageous in the treatment of tuberculosis and kidney damage in people with diabetes. The heat-processing method to strengthen the efficacy of P. ginseng has been well-defined based on a long history of ethnopharmacological evidence. The protective effects of P. ginseng on pathological conditions and renal damage associated with diabetic nephropathy in the animal models were markedly improved by heat-processing. The concentrations of less-polar ginsenosides (20(S)-Rg3, 20(R)-Rg3, Rg5, and Rk1) and maltol in P. ginseng were significantly increased in a heat-processing temperature-dependent manner. Based on researches in animal models of diabetes, ginsenoside 20(S)-Rg3 and maltol were evaluated to have therapeutic potential against diabetic renal damage. These effects were achieved through the inhibition of inflammatory pathway activated by oxidative stress and advanced glycation endproducts. These findings indicate that ginsenoside 20(S)-Rg3 and maltol are important bioactive constituents of heat-processed ginseng in the control of pathological conditions associated with diabetic nephropathy.
    Journal of ginseng research 10/2013; 37(4):379-388. · 2.26 Impact Factor
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    ABSTRACT: The root of ginseng is a famous functional food and a herbal medicine. Research into the development of a method for increasing the pharmaceutical effect of ginseng by conversion of ginsenosides, the major active components of ginseng, by high temperature and high pressure thermal processing has been conducted. However, changes in the structures of each ginsenoside by heat-processing and their contributions to anticancer activity have not been fully elucidated yet. Here, we investigated whether anticancer activity of ginsenosides, such as Rb1, Rb2, Rc, Rd and Re, was associated with changes in the structures of each ginsenoside by heat-processing in human stomach cancer AGS cells. Upon heat-processing at 120°C, most peaks of ginsenosides Rb1, Rb2, Rc and Rd disappeared, and the contents of less-polar ginsenosides 20(S,R)-Rg3, Rk1 and Rg5 were newly detected. From the quantitative analysis of ginsenosides, the generated amounts of less-polar ginsenosides were the highest after heat-processing of ginsenoside Rd. After heat-processing, the diol type ginsenosides Rb1, Rb2, Rc and Rd gained significant antiproliferative activity. In particular, ginsenoside Rd induced strongest cell death among the diol type ginsenosides, whereas the triol type gisenoside Re showed weak antiproliferative activity. Ginsenoside Rd-induced cell death was associated with caspase-dependent apoptosis. Taken together, these results demonstrate that deglycosylation of Rd contributes to improved anticancer activity of ginseng, and provide new insight on the mechanism of increased anticancer effects of ginsenosides upon heat-processing.
    Journal of Agricultural and Food Chemistry 08/2013; · 3.11 Impact Factor
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    ABSTRACT: Ginsenosides are the main active components of Panax ginseng. Structural changes in diol type ginsenosides along with generation of Maillard reaction products (MRPs) are strongly associated with increased free radical-scavenging activities. Ginsenoside Re, one of the major triol type ginsenosides of P. ginseng, possesses a hydrophobic four-ring steroid-like structure with hydrophilic sugar moieties at carbons-3 and -20. The aim of the present study was to identify changes in the structure, antioxidant and anticancer effects of ginsenoside Re upon Maillard reaction. Ginsenoside Re was transformed into less-polar ginsenosides, namely Rg(2), Rg(6) and F(4) by heat-processing. Free radical-scavenging activity of the ginsenoside Re-lysine mixture increased upon heat processing. This improved free radical-scavenging activity mediated by antioxidant MRPs, which were generated through Maillard reaction of a glucosyl moiety separated from carbon-20 of ginsenoside Re and lysine. The increased anticancer effect of ginsenoside Re-lysine mixture upon heat processing was mainly derived from the generation of less-polar ginsenosides through the regulation of Bcl-2 and Bax, as well as caspase-dependent apoptotic pathway. These results reported here have shed significant new lights on the mechanism of increased antioxidant and anticancer effects of P. ginseng upon heat processing.
    Food Chemistry 06/2013; 138(2-3):876-83. · 3.33 Impact Factor
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    ABSTRACT: Ginsenoside Re, one of the major triol type ginsenosides contained in Panax ginseng, has a hydrophobic four-ring steroid-like structure with hydrophilic sugar moieties at carbon-3 and -20. The aim of the present study was to identify the changes in structure and antioxidant activity of ginsenoside Re by the Maillard reaction, which has not been reported yet. The free radical-scavenging activity of ginsenoside Re-alanine mixture was increased by heat-processing. Ginsenoside Re was gradually changed into Rg(2), Rg(6) and F(4) by heat-processing, and the glucosyl moiety at carbon-20 was separated. The improved-free radical-scavenging activity by heat-processing was mediated by the generation of antioxidant Maillard reaction products (MRPs). Antioxidant MRPs were generated from the reaction of glucose and alanine. Based on the viability results of LLC-PK1 renal epithelial cells, MRPs and less-polar ginsenosides contributed to the combined renoprotective effect against oxidative renal damage. Maillard reaction is importantly involved in the increased antioxidant effect of ginsenoside by heat-processing.
    Food Chemistry 12/2012; 135(4):2430-5. · 3.33 Impact Factor
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    ABSTRACT: Levodopa (L-DOPA) is widely used for symptomatic management in Parkinson's disease. We recently showed that (-)-epigallocatechin-3-gallate, a tea polyphenol, not only inhibits L-DOPA methylation, but also protects against oxidative hippocampal neurodegeneration (PLoS ONE, 5: e11951, 2010). In the present study, we sought to determine several other common dietary phenolics, namely, tea catechins [(+)-catechin and (-)-epicatechin] and a representative flavonoid (quercetin), for their ability to modulate L-DOPA methylation and to protect against oxidative hippocampal injury. A combination of in vitro biochemical assays, cell culture-based mechanistic analyses, and in vivo animal models was used. While both tea catechins and quercetin strongly inhibit human liver catechol-O-methyltransferase (COMT)-mediated O-methylation of L-DOPA in vitro, only (+)-catechin exerts a significant inhibition of L-DOPA methylation in both peripheral compartment and striatum in rats. The stronger in vivo effect of (+)-catechin on L-DOPA methylation compared to the other dietary compounds is due to its better bioavailability in vivo. In addition, (+)-catechin strongly reduces glutamate-induced oxidative cytotoxicity in HT22 mouse hippocampal neurons in vitro through inactivation of the nuclear factor-κB signaling pathway. Administration of (+)-catechin also exerts a strong neuroprotective effect in the kainic acid-induced oxidative hippocampal neurodegeneration model in rats. In conclusion, (+)-catechin is a dietary polyphenolic that may have beneficial effects in L-DOPA-based treatment of Parkinson patients by inhibiting L-DOPA methylation plus reducing oxidative hippocampal neurodegeneration.
    Brain research 11/2012; · 2.46 Impact Factor
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    ABSTRACT: In a recent study, we showed that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two common omega-3 fatty acids, can cause ROS accumulation and subsequently induce caspase-8-dependent apoptosis in human breast cancer cells (Kang et al, PLoS ONE 5: e10296, 2010). In this study, we showed that the pancreas has a unique ability to accumulate EPA at a level markedly higher than several other tissues analyzed. Based on this finding, we sought to further investigate the anticancer actions of EPA and its analog DHA in human pancreatic cancer cells using both in vitro and in vivo models. EPA and DHA were found to induce ROS accumulation and caspase-8-dependent cell death in human pancreatic cancer cells (MIA-PaCa-2 and Capan-2) in vitro. Feeding animals with a diet supplemented with 5% fish oil, which contains high levels of EPA and DHA, also strongly suppresses the growth of MIA-PaCa-2 human pancreatic cancer xenografts in athymic nude mice, by inducing oxidative stress and cell death. In addition, we showed that EPA can concomitantly induce autophagy in these cancer cells, and the induction of autophagy diminishes its ability to induce apoptotic cell death. It is therefore suggested that combination of EPA with an autophagy inhibitor may be a useful strategy in increasing the therapeutic effectiveness in pancreatic cancer. J. Cell. Biochem. © 2012 Wiley Periodicals, Inc.
    Journal of Cellular Biochemistry 08/2012; · 3.06 Impact Factor
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    ABSTRACT: The aim of the present study was to verify the important role of Maillard reaction in the protective effect of heat-processed ginsenoside Re-serine mixture against oxidative stress-induced nephrotoxicity. The free radical-scavenging activity of ginsenoside Re-serine mixture was increased by heat-processing. Ginsenoside Re was transformed into less-polar ginsenosides such as Rg(2), Rg(6) and F(4) by heat-processing, and the glucose molecule at carbon-20 was separated. The improved-free radical-scavenging activity by heat-processing was mediated by the generation of antioxidant Maillard reaction products (MRPs) from the reaction of glucose with serine. Moreover, MRPs from ginsenoside Re-serine mixture showed protective effect against cisplatin-induced renal epithelial cell damage.
    Bioorganic & medicinal chemistry letters 07/2012; 22(17):5475-9. · 2.65 Impact Factor
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    ABSTRACT: Reactive oxygen species play critical role in kidney damage. Free radical-scavenging activities of Panax ginseng are known to be increased by heat-processing. The structural change of ginsenoside and the generation of Maillard reaction products (MRPs) are closely related to the increased free radical-scavenging activities. In the present study, we have demonstrated the Maillard reaction model experiment using ginsenoside Re and glycine mixture to identify the renoprotective effect of MRPs from ginseng or ginsenosides. Ginsenoside Re was transformed into less-polar ginsenosides, namely Rg2, Rg6 and F4 by heat-processing. The free radical-scavenging activity of ginsenoside Re-glycine mixture was increased in a temperature-dependant manner by heatprocessing. The improved free radical-scavenging activity by heat-processing was mediated by the generation of antioxidant MRPs which led to the protection of LLC-PK1 renal epithelial cells from oxidative stress. Although the free radical scavenging activities of less-polar ginsenosides were weak, they could protect LLC-PK1 cells from oxidative stress. Therefore, MRPs and less-polar ginsenosides contributed to the combined renoprotective effects against oxidative renal damage.
    Journal of ginseng research 07/2012; 36(3):256-262. · 2.26 Impact Factor
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    ABSTRACT: Ghrelin was first identified and characterized from rat stomach as an endogenous ligand for the growth hormone secretagogue (GHS) receptor (GHS-R). Ghrelin also acts as an orexigenic factor and regulates energy balance in rodents. In goldfish, native ghrelin consists of 11 molecular variants, the major form being a 17-residue peptide with n-octanoic acid modification (n-octanoyl ghrelin17), and intraperitoneal (IP) administration of n-octanoyl ghrelin17 induces central actions such as stimulation of food intake and suppression of locomotor activity through capsaicin-sensitive afferents. Four types of GHS-Rs (1a-1, 1a-2, 2a-1 and 2a-2) have been identified in goldfish, and one GHS, GHRP-6, can activate only GHS-R2a-1 in vitro. However, there is no information about the effect of GHRP-6 on food intake and locomotor activity in goldfish in vivo. Therefore, in the present study, we examined whether IP-administered GHRP-6 would mimic the orexigenic action of n-octanoyl ghrelin17 and its suppression of locomotor activity. IP administration of GHRP-6 at 1pmol/g body weight (BW) stimulated food intake, and was equipotent to the orexigenic action of n-octanoyl ghrelin17 at 10 pmol/g BW. IP-injected GHRP-6 at 1 pmol/g BW also induced a significant decrease of locomotor activity, as was the case for IP-injected n-octanoyl ghrelin17 at 10 pmol/g BW. The action of GHRP-6 was blocked by IP-preinjected capsaicin at 160 nmol/g BW. These results suggest that the central action of GHRP-6 might be mediated via the GHS-R2a-1-signaling pathway, and subsequently through capsaicin-sensitive afferents in goldfish.
    Peptides 02/2012; 34(2):324-8. · 2.52 Impact Factor

Publication Stats

746 Citations
167.93 Total Impact Points

Institutions

  • 2014
    • Ulsan University Hospital
      Urusan, Ulsan, South Korea
    • Gachon University
      Sŏngnam, Gyeonggi Province, South Korea
  • 2011–2014
    • Korea Institute of Science and Technology
      • Center for Neuro-Medicine
      Sŏul, Seoul, South Korea
  • 2013
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
  • 2010–2012
    • Kansas City VA Medical Center
      Kansas City, Missouri, United States
  • 2006–2012
    • University of Toyama
      • Institute of Natural Medicine
      Тояма, Toyama, Japan
    • Toyama Medical and Pharmaceutical University
      Тояма, Toyama, Japan
  • 2008–2009
    • Seoul National University
      • College of Pharmacy
      Seoul, Seoul, South Korea
    • Busan Kyungsang College
      Tsau-liang-hai, Busan, South Korea
  • 2007–2008
    • Mokpo National University
      • Department of Medicinal Plant Resources
      Moppo, South Jeolla, South Korea