Sang Un Choi

Korea Research Institute of Chemical Technology, Daiden, Daejeon, South Korea

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Publications (141)278.12 Total impact

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    ABSTRACT: Phytochemical investigation of the twigs of Chaenomeles sinensis led to the isolation and identification of six new lignan glycosides, chaenomiside A-F (1-6), along with five known ones (7-11). Their chemical structures were determined by spectroscopic methods, including NMR, MS, ECD, and GC/MS analyses. All the isolated compounds (1-11) were tested for their inhibitory effects on nitric oxide (NO) production in lipopolysaccharide-activated murine microglial cells and the secretion of nerve growth factor (NGF) in a C6 rat glioma cell line. Compound 6 significantly reduced NO levels in the murine microglia BV2 cells with an IC50 value of 21.3 μM, and compounds 1, 3, and 6 were potent stimulants of NGF release with stimulation levels of 151.74 ± 6.77%, 144.31 ± 7.49%, and 167.61 ± 18.5%, respectively.
    Journal of Natural Products 04/2015; DOI:10.1021/acs.jnatprod.5b00090 · 3.95 Impact Factor
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    ABSTRACT: Because of the recent discovery of brown adipose tissues in adult humans, brown adipose tissues have garnered additional attention. Many studies have attempted to transform the precursor cells within the white adipocyte cultures to Brite (brown-in-white) cells by using genomic modification or pharmacological activation in order to determine the therapeutic effect of obesity. However, genome-scale analysis of the genetic factors governing the development of white and brown adipose tissues remains incomplete. In order to identify the key genes that regulate the development of white and brown adipose tissue in mice, a transcriptome analysis was performed on the adipose tissues. Network analysis of differentially expressed genes indicated that Trim30 and Ucp3 play pivotal roles in energy balance and glucose homeostasis. In addition, it was discovered that identical biological processes and pathways in the white and brown adipose tissues might be regulated by different genes. Trim30 and Ucp3 might be used as genetic markers to precisely represent the stage of obesity during the early and late stages of adipose tissue development, respectively. These results may provide a stepping-stone for future obesity-related studies. Copyright © 2015. Published by Elsevier B.V.
    Gene 04/2015; 565(1). DOI:10.1016/j.gene.2015.03.077 · 2.08 Impact Factor
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    ABSTRACT: A new aliphatic alcohol, (2R,6R)-oct-7-ene-2,6-diol (1), and seven other known compounds (2-8) were isolated from Acorus gramineus rhizomes. The structure of 1 was elucidated by a combination of extensive spectroscopic analyses, including 2D NMR, HR-MS, and the modified Mosher's method. Compounds 3-8 displayed consistent antiproliferative activities against the cell lines tested with IC50 values ranging from 7 to 48 μm.
    Bioscience Biotechnology and Biochemistry 04/2015; DOI:10.1080/09168451.2015.1031079 · 1.21 Impact Factor
  • ChemInform 04/2015; 46(15). DOI:10.1002/chin.201515266
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    ABSTRACT: The two new diterpenoids (Ia) and (Ib) are isolated from the leaves of Thuja orientalis together with 7 known compounds.
    ChemInform 03/2015; 46(10). DOI:10.1002/chin.201510256
  • The Journal of Antibiotics 01/2015; DOI:10.1038/ja.2015.2 · 2.04 Impact Factor
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    ABSTRACT: Toxicodendron vernicifluum (Stokes) F.A. Barkley (Anacardiaceae) has traditionally been used as a food supplement and in traditional herbal medicine to treat inflammatory diseases and cancers for centuries in Korea. This study was designed to isolate the bioactive constituents from the ethanol extract of T. vernicifluum bark and evaluate their cytotoxic and anti-inflammatory activities. Bioassay-guided fractionation and chemical investigation of the ethanol extract of T. vernicifluum bark resulted in the isolation and identification of three new polyphenols (1-3) and six flavonoids (4-9). The structures of the isolated compounds were elucidated by spectroscopic analysis, including 1D and 2D nuclear magnetic resonance (NMR) ((1)H, (13)C, COSY, HMQC and HMBC experiments), and high resolution (HR)-mass spectrometry, and their absolute configurations were further confirmed by chemical methods and circular dichroism (CD) data analysis. Compounds 1-9 were evaluated for their antiproliferative activities against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15), and anti-inflammatory activities by measuring nitric oxide (NO) levels in the medium of murine microglia BV-2 cells. The isolated compounds were characterized as in the following: three new polyphenols, rhusopolyphenols G-I (1-3) and six flavonoids including two aurones, 2- benzyl- 2, 3', 4', 6- tetrahydroxybenzo[b] furan- 3(2H) - one (4), sulfuretin (5), two dihydroflavonols, (+)-(2S,3R)-fustin (6), (+)-epitaxifolin (7), one chalcone, butein (8), and one flavonol, fisetin (9). The published NMR assignments of 4 were corrected by the detailed analysis of spectroscopic data in this study. Among the tested compounds, compounds 4-9 showed antiproliferative activity against the tested cells, with IC50 values of 4.78-28.89μM. Compounds 5 and 8 significantly inhibited NO production in lipopolysaccharide (LPS)-stimulated BV-2 cells with IC50 values of 23.37 and 11.68μM, respectively. Polyphenols including flavonoids were one of the main constituents of T. vernicifluum bark, and activities demonstrated by the isolated compounds support the ethnopharmacological use of T. vernicifluum as anti-cancer and/or anti-inflammatory agents. Copyright © 2015. Published by Elsevier Ireland Ltd.
    Journal of Ethnopharmacology 01/2015; 162. DOI:10.1016/j.jep.2014.12.071 · 2.94 Impact Factor
  • Journal of the Brazilian Chemical Society 01/2015; DOI:10.5935/0103-5053.20150113 · 1.25 Impact Factor
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    ABSTRACT: isolation, structure elucidation and acetylcholinesterase inhibition of the new amaryllidaceae alkaloid, 6-hydroxytazettine (I), and 17 related alkaloids
    Bulletin- Korean Chemical Society 12/2014; 35(12):3665-3667. DOI:10.5012/bkcs.2014.35.12.3665 · 0.84 Impact Factor
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    ABSTRACT: An extensive phytochemical investigation on the roots of Glycyrrhiza uralensis led to the isolation of two new minor chalcone acetylglycosides, i.e., 6″-O-acetylisoliquiritin (1) and 6″-O-acetylneoisoliquiritin (2), including 16 kinds of known constituents (3–18) of flavonoids, chalcones and triterpene saponins. The chemical structures of 1 and 2 were established by spectroscopic analyses of them, particularly by the aid of two-dimensional NMR experiments, COSY, DEPT, HSQC and HMBC. Some isolated components except 1 and 2 exhibited significant inhibitory effects on the proliferation of cultured tumor cell lines, such as A549, SK-OV-3, A-498, and HCD15, in vitro.
    Archives of Pharmacal Research 12/2014; DOI:10.1007/s12272-014-0526-y · 1.75 Impact Factor
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    ABSTRACT: Holophyllin A (1), a novel rearranged abietane-type diterpenoid was isolated, together with a new diterpene glycoside, holophyllin B (2), from the trunk of Abies holophylla. The structures of 1 and 2 were established by extensive spectroscopic analyses and their absolute configurations were determined by ECD calculation. All the isolates were tested for their inhibitory effects on NO production in LPS-activated murine microglial cells.
    Tetrahedron Letters 11/2014; 55(47). DOI:10.1016/j.tetlet.2014.10.030 · 2.39 Impact Factor
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    ABSTRACT: A bioassay-guided fractionation and chemical investigation of the MeOH extract of Raphanus sativus seeds resulted in the isolation and identification of eight phenylpropanoid sucrosides (1-8) including two new compounds, named raphasativuside A and B (1-2) from the most active CHCl3-soluble fraction. The structures of these new compounds were elucidated through spectral analysis, including extensive 2D-NMR data, and chemical reaction experiments. We evaluated the anti-inflammatory effects of 1-8 in lipopolysaccharide (LPS)-stimulated murine microglia BV2 cells. Compounds 2 and 5 exhibited significant inhibitory effect on nitric oxide production in LPS-activated BV-2 cells with IC50 values of 21.63 and 26.96 μM, respectively. All isolates were also evaluated for their antiproliferative activities against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15). Compounds 1–7 showed consistent cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines with IC50 values of 6.71–27.92 μM. Additionally, the free-radical scavenging activity of 1-8 was assessed using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay where compounds 1, 3, and 4 scavenged DPPH radical strongly with IC50 values of 23.05, 27.10, and 29.63 μg/mL, respectively.
    Bioorganic & Medicinal Chemistry Letters 11/2014; 25(1). DOI:10.1016/j.bmcl.2014.11.001 · 2.33 Impact Factor
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    ABSTRACT: In the course of our continuing search for bioactive constituents of Korean medicinal plants, we isolated five new oxylipins, chaenomic acid A-E (1-5), and six known ones (6-11) from the twigs of Chaenomeles sinensis. The structures of the new compounds (1-5) were determined by spectroscopic methods, including 1D and 2D NMR ((1)H and (13)C NMR, (1)H-(1)H COSY, HMQC, HMBC, and NOESY), olefin cross-metathesis, and LC/MS analysis. The known compounds (6-11) were identified by comparison of their spectroscopic data and specific optical rotation with the reported data. The isolated compounds (1-11) were tested for their inhibitory effects on nitric oxide production in lipopolysaccharide-activated murine microglial cells and for their cytotoxic activities against four human cancer cell lines (A549, SK-OV-3, A498, and HCT-15).
    Lipids 09/2014; 49(11). DOI:10.1007/s11745-014-3953-0 · 2.35 Impact Factor
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    ABSTRACT: We report a series of phenyl substituted pyridazin-3-ones substituted with morpholino-pyrimidines. The SAR of the phenyl was explored and their c-Met kinase and cell-based inhibitory activity toward c-Met driven cell lines were evaluated. Described herein is a potent c-Met inhibitor by structural modification of the parent morpholino-pyridazinone scaffold, with particular focus on the phenyl and pyrimidine substituents.
    Bioorganic & Medicinal Chemistry Letters 09/2014; 24(21). DOI:10.1016/j.bmcl.2014.08.067 · 2.33 Impact Factor
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    ABSTRACT: As a part of an ongoing search for bioactive constituents from Korean medicinal plants, the phytochemical investigations of the twigs of Salix glandulosa afforded 12 new phenolic glycosides (1-12) and a known analogue (13). The structures of 1-13 were characterized by a combination of NMR methods ((1)H and (13)C NMR, (1)H-(1)H COSY, HMQC, and HMBC), chemical hydrolysis, and GC/MS. The absolute configuration of 13 [(1R,2S)-2-hydroxycyclohexyl-2'-O-trans-p-coumaroyl-β-d-glucopyranoside] was determined for the first time. Compounds 1-3, 6, and 7 exhibited inhibitory effects on nitric oxide production in lipopolysaccharide-activated murine microglial cells (IC50 values in the range 6.6-20.5 μM).
    Journal of Natural Products 08/2014; 77(8). DOI:10.1021/np500488v · 3.95 Impact Factor
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    ABSTRACT: In the search for antitumor compounds from Korean natural resources, activity-guided fractionation and purification processes were used on seeds of Morning glory (Pharbitis nil). Air-dried P. nil seeds were extracted with ethanol and separated into n-hexane, chloroform, ethyl acetate, and n-butanol. Four new lignans, pharbilignans A-D (1-4) were isolated from the most active ethyl acetate fraction of the ethanol extract. Their structures were characterized on the basis of spectroscopic methods, including one- and two-dimensional nuclear magnetic resonance (NMR) techniques, high resolution mass spectrometry (HRMS), and circular dichroism (CD) spectroscopy. The cytotoxic activities of the isolates (1-4) were evaluated by determining their inhibitory effects on four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15) using a sulforhodamine B (SRB) bioassay. Pharbilignan C (3) showed potent cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines with IC50 values of 1.42, 0.16, 0.20, and 0.14 μM, respectively. On the basis of the expanded understanding that inflammation is a crucial cause in tumor progress, we also evaluated anti-inflammatory activity of the isolates (1-4). Pharbilignan C (3) strongly inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 microglia cell line with an IC50 value of 12.8 μM.
    Journal of Agricultural and Food Chemistry 07/2014; 62(31). DOI:10.1021/jf501470k · 3.11 Impact Factor
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    ABSTRACT: Two new spirostane-steroidal saponins, bletilnoside A (1) and bletilnoside B (2), together with five known compounds, 3–7, were isolated from the roots of Bletilla striata (Thunb.) Reichb. F. The structures of the new compounds were determined based on their 1D- and 2D-NMR spectral data. The isolated compounds 1–7 were tested for cytotoxicity against four human tumor cells (A549, SK-OV-3, SK-MEL-2, and HCT15) in vitro using a sulforhodamin B bioassay, and compounds 1, 2, and 5 showed significant cytotoxicities against all tested tumor cell lines with IC50 values ranging from 3.98±0.16 to 12.10±0.40 μM.
    Helvetica Chimica Acta 01/2014; 97(1). DOI:10.1002/hlca.201300102 · 1.39 Impact Factor
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    ABSTRACT: A bioassay-guided fractionation and chemical investigation of the MeOH extract from the twigs of Lindera glauca (SIEB. et ZUCC.) BLUME resulted in the isolation and identification of six lignans (1-6) including three new lignan derivatives, named linderuca A (1), B (2), and C (3). The structures of the new compounds (1-3) were determined on the basis of spectroscopic analyses, including two dimensional NMR and circular dichroism (CD) spectroscopy studies. The cytotoxic activities of the isolates (1-6) were evaluated by determining their inhibitory effects on human tumor cell lines. Compounds 1-5 showed antiproliferative activities against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines with IC50 values of 7.79-29.42 µM. Based on the understanding that inflammation is a crucial cause of tumor progression, we also investigated the anti-inflammatory activities of the isolates (1-6) in the lipopolysaccharide-stimulated murine microglia BV-2 cell line by measuring nitric oxide (NO) levels. The new lignans (1-3) significantly inhibited NO production with IC50 values of 12.10, 9.48, and 9.87 µM, respectively, without cytotoxicity.
    CHEMICAL & PHARMACEUTICAL BULLETIN 01/2014; 62(11):1136-40. DOI:10.1248/cpb.c14-00381 · 1.38 Impact Factor
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    ABSTRACT: Raphanus sativus seeds (Brassicaceae) known as Raphani Semen have long been used as anti-cancer and/or anti-inflammatory agents in Korean traditional medicine. This study was designed to isolate the bioactive constituents from the seed extracts of Raphanus sativus and evaluate their anti-inflammatory and antitumor activities. Bioassay-guided fractionation and chemical investigation of a methanolic extract of the seeds of Raphanus sativus led to the isolation and identification of seven 4-methylthio-butanyl derivatives. Structural elucidation of the isolated compounds was carried out using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy techniques ((1)H, (13)C, COSY, HMQC and HMBC experiments) and mass spectrometry. The isolated compounds were characterized as in the following: three new 4-methylthio-butanyl derivatives, sinapoyl desulfoglucoraphenin (1), (E)-5-(methylsulfinyl)pent-4-enoxylimidic acid methyl ester (2), and (S)-5-((methylsulfinyl)methyl)pyrrolidine-2-thione (3), together with four known compounds, 5-(methylsulfinyl)-4-pentenenitrile (4), 5-(methylsulfinyl)-pentanenitrile (5), sulforaphene (6), and sulforaphane (7). Full NMR data assignments of the three known compounds 4-6 were also reported for the first time. We evaluated the anti-neuroinflammatory effect of 1-7 in lipopolysaccharide-stimulated murine microglia BV2 cells. Compound 1 significantly inhibited nitrite oxide production with IC50 values of 45.36μM. Moreover, it also reduced the protein expression of inducible nitric oxide synthase. All isolates were also evaluated for their antiproliferative activities against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15), and all of them showed antiproliferative activity against the HCT-15 cell, with IC50 values of 8.49-23.97μM. 4-Methylthio-butanyl derivatives were one of the main compositions of Raphanus sativus seeds, and activities demonstrated by the isolated compounds support the ethnopharmacological use of Raphanus sativus seeds (Brassicaceae) as anti-cancer and/or anti-inflammatory agents.
    Journal of ethnopharmacology 11/2013; 151(1). DOI:10.1016/j.jep.2013.11.003 · 2.94 Impact Factor
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    ABSTRACT: A phytochemical investigation on the essential oil of Thuja orientalis resulted in the isolation and identification of three new sesquiterpenes, 3α-methoxy-4α-epoxythujopsane (1), Δ3,15-4β-epoxythujopsene (2), and Δ3,4-thujopsen-2,15-diol (3), together with eight known sesquiterpenoids (4-11). The structures of these new compounds were elucidated based on spectroscopic data analyses including extensive 2D-NMR data and HR-ESIMS. The full assignments of 1H and 13C NMR chemical shifts for thujopsadiene (4) were obtained by 2D-NMR for the first time. All compounds (1-11) showed antiproliferative activities against the SK-OV-3 and SK-MEL-2 cell lines with IC50 values of 5.85-28.64 µM. In addition, compounds 1, 3, 4, 7, 8, and 9 significantly inhibited nitric oxide production in lipopolysaccharide-activated BV-2 cells with IC50 values of 3.93-17.85 µM without cell toxicity.
    Planta Medica 10/2013; 79(17). DOI:10.1055/s-0033-1350952 · 2.34 Impact Factor

Publication Stats

1k Citations
278.12 Total Impact Points

Institutions

  • 1992–2015
    • Korea Research Institute of Chemical Technology
      • Division of Drug Discovery Research
      Daiden, Daejeon, South Korea
  • 2001–2013
    • Sungkyunkwan University
      • School of Pharmacy
      Seoul, Seoul, South Korea
  • 1998
    • Yonsei University
      • Department of Biology
      Sŏul, Seoul, South Korea