Ji Ho Yun

Korea Institute of Science and Technology, Sŏul, Seoul, South Korea

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Publications (11)19.35 Total impact

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    ABSTRACT: Abstract Alcohol is a severe hepatotoxicant that causes liver abnormalities such as steatosis, cirrhosis, and hepatocarcinoma. Crepidiastrum denticulatum (CD) is a well-known, traditionally consumed vegetable in Korea, which was recently reported to have bioactive compounds with detoxification and antioxidant properties. In this study, we report the hepatoprotective effect of CD extract against chronic alcohol-induced liver damage in vivo. The rats that were given CD extract exhibited decreased alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transpeptidase activities, which are liver damage markers that are typically elevated by alcohol consumption. The results were confirmed by histopathology with hematoxylin and eosin staining. Chronic alcohol consumption induced the formation of alcoholic fatty liver. However, treatment with CD extract dramatically decreased the hepatic lipid droplets. Treatment with CD extract also restored the antioxidative capacity and lipid peroxidation of the liver that had been changed by alcohol consumption. Furthermore, treatment with CD extract normalized the activities of the antioxidative enzymes superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase, which had been decreased by alcohol consumption. The results indicate that CD extract has protective effects against chronic alcohol hepatotoxicity in rats by increasing the liver's antioxidant capacity, and has potential as a dietary supplement intervention for patients with alcohol-induced liver damage.
    Journal of medicinal food 03/2014; · 1.39 Impact Factor
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    ABSTRACT: Abstract Phase II detoxification enzymes are known to play essential roles in the detoxification and elimination of activated carcinogens during tumor initiation, while apoptosis is one of the most important chemopreventive targets for inhibiting tumor promotion in cancer. In this study, we investigated the cancer chemopreventive activity of two plant extracts, the ethanolic extract of Adenocaulon himalaicum (AHE) and the butanolic fraction of AHE (AHB). Both, the AHE and AHB induced NQO1 activity and had relatively high chemoprevention indices (CI=12.4). The AHE and AHB were associated with increased NQO1 and HO-1 mRNA levels via Nrf2-ARE pathway activation. In addition, the AHB increased CYP1A1 activity through AhR-XRE pathway activation. We also found that the AHE and AHB induced apoptosis, as evidenced by phosphatidylserine externalization, an increase in the sub-G0/G1 content, chromatin condensation, poly(ADP-ribose) polymerase cleavage, and p53 induction. These data suggest that AHE and AHB act as bifunctional inducers and that their chemopreventive effects result from the biphasic induction of phase II detoxification enzymes and apoptosis. Therefore, these results suggest that A. himalaicum plant extracts have potential for use as chemopreventive agents for the prevention and/or treatment of human cancers.
    Journal of medicinal food 08/2013; 16(8):701-10. · 1.39 Impact Factor
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    ABSTRACT: Hosta capitata is a plant genus of the family Liliaceae, native to South Korea, a herbaceous perennial, occurs in the southwestern Korean Peninsula and southwestern Japan, usually found in pine-oak understories. The methanol extracts of the whole plant material were found to have antifungal activity against human pathogenic fungi such as Saccharomyces cerevisiae, Candida albican and one airborne fungus Cladosporium cladosporioide. The activity-guided fractionation gave us to isolated five compounds from butanol fraction using silica gel open column chromatography, sephadex-LH20, preparative HPLC and analytical HPLC. LC-MS and NMR were used for structural elucidations. The structures of three flavonoids (1-3) were identified as kaempferol-3-O-β-D-glucopyranosyl-(1¦2)-β-D-glucopyranoside-7-O-β-D-glucopyranoside (1), kaempferol-3-O-α-L-rhamnopyranosyl-(1¦6)-β-D-glucopyranosyl-(1¦2)-β-D-glucopyranoside (2), kaempferol-3-O-β-D-glucopyranosyl-(1¦2)-β-D-glucopyranoside (3). The structure elucidation of two saponins (HC-4) and (HC-7) are under studying. All pure compounds were evaluated by disc diffusion method, cell viability, cell cycle analysis, and dimorphic transition. Compound (HC-7) was found to have antifungal activity against both human pathogenic fungi, S.cerevisiae and C.albican. This study was the first investigation antifungal activity of extract, fractions (n-hexane, ethyl acetate, n-butthanol,water), and purified compounds isolated from H.capitata.
    12/2012, Degree: Master of Science, Supervisor: Byung Hun Um
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    ABSTRACT: Handaeri-gomchi (Ligularia fischeri var. spiciformis Nakai) (LF) is well known as a medicinal plant in Korea, especially to treat a variety of human disease including hepatic function failure. In this study, we examined the activity of LF extract against the liver injuries and oxidative stress by chronic alcohol in Spargue-Dawley rats. Severe liver damage caused by alcohol intake with increasing activity of hepatic markers was decreased in the group of rats fed LF extract. The results were confirmed through hematoxylin and eosin staining. Antioxidative capacity was decreased by alcohol but it was recovered by LF extract. Elevated indicators of oxidative stress by chronic alcohol were diminished in the group of LF extract. Furthermore, LF extracts increased antioxidative capacity and the activity of antioxidant enzymes. In conclusion, LF extract has a protective effect against chronic alcohol hepatotoxicity, suggesting it could be developed as a functional food or medicine for protection of liver disease.
    Food science and biotechnology 12/2011; 20(6):1655-1661. · 0.70 Impact Factor
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    ABSTRACT: We report that daurinol, a novel arylnaphthalene lignan, is a promising potential anticancer agent with adverse effects that are less severe than those of etoposide, a clinical anticancer agent. Despite its potent antitumor activity, clinical use of etoposide is limited because of its adverse effects, including myelosuppression and the development of secondary leukemia. Here, we comprehensively compared the mechanistic differences between daurinol and etoposide because they have similar chemical structures. Etoposide, a topoisomerase II poison, is known to attenuate cancer cell proliferation through the inhibition of DNA synthesis. Etoposide treatment induces G(2)/M arrest, severe DNA damage, and the formation of giant nuclei in HCT116 cells. We hypothesized that the induction of DNA damage and nuclear enlargement due to abnormal chromosomal conditions could give rise to genomic instability in both tumor cells and in actively dividing normal cells, resulting in the toxic adverse effects of etoposide. We found that daurinol is a catalytic inhibitor of human topoisomerase IIa, and it induces S-phase arrest through the enhanced expression of cyclins E and A and by activation of the ATM/Chk/Cdc25A pathway in HCT116 cells. However, daurinol treatment did not cause DNA damage or nuclear enlargement in vitro. Finally, we confirmed the in vivo antitumor effects and adverse effects of daurinol and etoposide in nude mice xenograft models. Daurinol displayed potent antitumor effects without any significant loss of body weight or changes in hematological parameters, whereas etoposide treatment led to decreased body weight and white blood cell, red blood cell, and hemoglobin concentration.
    Neoplasia (New York, N.Y.) 11/2011; 13(11):1043-57. · 5.48 Impact Factor
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    ABSTRACT: Improvement of liver function is one of the most popular commercial health claims of functional foods in Asian countries, including Korea. After examining the potential of several traditional Korean wild vegetables for enhancing liver function, we found that Youngia denticulata Kitam. has strong hepatoprotective effects against oxidative stress induced by tert-butylhydroperoxide (t-BHP). We are the first to report that the extract and ethyl acetate fractions of Y. denticulata have radical scavenging activities and inhibit oxidative stress-induced cell death and DNA damage in HepG2 cells. The extract and ethyl acetate fractions significantly decreased cellular reactive oxygen species production and apoptosis induced by t-BHP in HepG2 cells. In addition, they prevented the depletion of cellular glutathione, which is an important defense molecule against oxidizing xenobiotics. Chlorogenic acid and 3,5-dicaffeoylquinic acid were found to be major active components responsible for the activity of Y. denticulata and could serve as marker compounds for standardization. These data suggest that Y. denticulata could be promoted as a potential antioxidative functional food candidate, particularly for hepatoprotection against oxidative stress.
    Journal of medicinal food 09/2011; 14(10):1198-207. · 1.39 Impact Factor
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    ABSTRACT: In the present study, we isolated a polyacetylene, gymnasterkoreayne B (GKB), from Gymnaster koraiensis and investigated the effect of GKB on the protection from oxidative stress-induced cytotoxicity through induction of the expression of cellular defense enzymes. GKB induced mRNA expression and enzyme activity of NAD(P)H:quinone oxidoreductase (NQO1) in vitro and in vivo, and potently increased expression of many cellular defense genes including glutathione-S-transferases, UDP-glucuronosyltransferase, and glutathione reductase (GSR) in normal rat liver. The nuclear factor erythroid 2-related factor 2 (Nrf2) which is known to induce various antioxidant and cytoprotective genes, and the genes containing the antioxidant response element (ARE), including NQO1, hemeoxygenease-1, GSR were induced by GKB in HepG2 human hepatocarcinoma cells. Pre-treatment of the cells with GKB accelerated the production of glutathione and mitigated menadione-induced cytotoxicity in HepG2 cells. Taken together, we found that GKB was a novel inducer of phase II detoxification enzymes and cellular defense enzymes, resulting in protection of the cells from oxidative stress and hepatotoxicity through regulation of detoxifying and antioxidant systems.
    Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 11/2010; 48(11):3035-41. · 2.99 Impact Factor
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    ABSTRACT: Cancer chemoprevention is thought to occur either by blocking the initiation of or suppressing the promotion of carcinogenesis. Phase II detoxification enzymes are known to play important roles in cancer chemoprevention because they enhance cytoprotection through detoxification and elimination of activated carcinogens at tumor initiation. Apoptosis is one of the most important inhibitory targets for tumor promotion. In this study, we have investigated the cancer chemopreventive activity of the ethanolic extract of Carpesium abrotanoides (CAE). We found that CAE induced quinone reductase [also known as NAD(P)H:quinone oxidoreductase (NQO1)] activity, increased NQO1 mRNA and protein expression, and had a relatively high chemoprevention index (12.04). CAE also significantly activated the antioxidant response element through the nuclear accumulation of NF-E2-related factor 2 in HCT116. Interestingly, we also found that CAE induced apoptosis, as evidenced by the externalization of phosphatidylserine, increased sub-G(0)/G(1) content, chromatin condensation, poly(ADP-ribose) polymerase cleavage, and p53. These data suggest that the chemopreventive effects of C. abrotanoides can result from both the induction of phase II detoxification enzymes and from apoptosis. Thus, CAE could potentially be developed as a cancer chemopreventive agent for prevention or treatment of human cancers.
    Journal of medicinal food 02/2010; 13(1):39-46. · 1.39 Impact Factor
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    ABSTRACT: Many phytochemicals are known to exert cancer chemopreventive activity by eliminating chemical carcinogens or toxic xenobiotics through the action of detoxification enzymes. In this study, we investigated the cancer chemopreventive effects of youngiasides isolated from Crepidiastrum denticulatum. These youngiasides significantly induced quinone reductase (QR) activity in mouse hepatoma Hepa-1c1c7 cells, and showed a relatively high chemoprevention index (CI; divided IC(50) value with CD value). The youngiasides also significantly induced transcriptional activation of QR in Hepa-QR-secreted alkaline phosphatase (SEAP) cells, which is a stable cell line containing the intact promoter region of QR. In order to determine if upregulation of QR by the youngiasides was mediated through a mono-functional or bi-functional mechanism, we examined the nuclear factor-E2 p45-related factor 2(Nrf2)-antioxidant response element (ARE) and aryl hydrocarbon receptor (AhR)-xenobiotic response element (XRE) pathways, which are two major pathways, involved in regulation of Phase I and/or Phase II detoxification enzymes. The youngiasides increased the cytochrome P450 1A1 (CYP1A1) mRNA and protein levels in human colorectal cancer Caco-2 cells and also increased the QR mRNA and protein levels in Caco-2 cells through ARE and XRE activation which resulted from translocation of Nrf2 and AhR into the nucleus. These results suggest that regulation of QR by the youngiasides was due to bi-functional induction through the Nrf2-ARE and AhR-XRE pathways. Thus, these youngiasides as bi-functional inducers of QR have potential as cancer chemopreventive agents.
    Biological & Pharmaceutical Bulletin 01/2010; 33(10):1650-7. · 1.85 Impact Factor
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    ABSTRACT: The antioxidative activities of hydrolysates isolated from the freshwater rotifer using enzymes Alcalase, α-chymotrypsin, Neutrase, papain, pepsin, and trypsin were identified and evaluated using direct free radical scavenging activity. Among the six hydrolysates, Neutrase hydrolysate had the highest antioxidative activity compared to the other hydrolysates. The free radical scavenging activity of Neutrase hydrolsysate was 45.26% at 1.0mg/mL. The peptide demonstrating the strongest antioxidative activity was isolated from the hydrolysate using consecutive chromatographic methods including Sephadex G-25 Gel chromatography and high performance liquid chromatography on an ODS column. The IC50 value of purified antioxidant peptide was 100.8 μM. The antioxidant peptide was identified as a sequence of 10 amino acids, Gly-His-Asp-Gly-Tyr-Glu-Pro-Leu-Ser-Ser (1091 Da) by N-terminal amino acid sequence analysis. The purified peptide exhibited an inhibitory effect against induced DNA oxidation. Our results suggested that antioxidative hydrolysates freshwater rotifer may be useful ingredients in food and nutraceutical applications.
    Journal of the Korean Society for Applied Biological Chemistry 01/2010; 53(2). · 0.43 Impact Factor
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    ABSTRACT: The upregulation of phase II detoxification genes is believed to play an important role in cancer prevention. The molecular mechanism underlying the changes in gene expression that accompany cancer prevention involves activation of the transcription factor, NF-E2-related factor 2 (Nrf2). In traditional medicine, the fruit of Schisandra chinensis Baill is used as a tonic, an anti-tussive and an anti-aging drug. In the current study, nine lignans were isolated from S. chinensis and tested for their ability to induce quinone reductase (QR) activity in Hepa1c1c7 mouse hepatocarcinoma cells. Tigloylgomisin H (TGH) and angeloylgomisin H (AGH) significantly induced QR activity and exhibited a relatively high chemoprevention index (CI) (10.80 and 4.59, respectively) as compared to control. TGH also induced QR activity in BPrc1 mouse hepatocarcinoma cells as well, which are defective in aryl hydrocarbon nuclear translocator (Arnt). In HepG2 human hepatocarcinoma cells, TGH significantly activated gene expression mediated by the antioxidant response element (ARE), a key regulatory region in the promoters of detoxification enzymes, through the nuclear accumulation of Nrf2. The results of the current study suggest that TGH functions as a novel monofunctional inducer that specifically upregulates phase II enzymes through the Nrf2-ARE pathway. TGH thus represents a potential liver cancer prevention agent.
    Planta Medica 06/2009; 75(12):1314-8. · 2.35 Impact Factor