Hye Kyong Kim
Postdoc / guest
- Name
- Dr. H.K. Kim
- Telephone
- +31 71 527 5110
- h.k.kim@biology.leidenuniv.nl
Postdoc / guest
- Science
- Instituut Biologie Leiden
- IBL Plant Sciences
- Salome Abarca L.F., Hondel C.A.M.J.J. van der, Erol Ö., Klinkhamer P.G.L., Kim H.K. & Choi Y.H. (2021), HPTLC-based chemical profiling: an approach to monitor plant metabolic expansion caused by fungal endophytes, Metabolites 11(3): 174.
- Wei X., Vrieling K., Kim H.K., Mulder P.P.J. & Klinkhamer P.G.L. (2021), Application of methyl jasmonate and salicylic acid lead to contrasting effects on the plant's metabolome and herbivory, Plant Science 303: 110784.
- Bouguellid G., Russo C., Lavorgna M., Piscitelli C., Ayouni K., Wilson E., Kim H.K., Verpoorte R., Choi Y.H., Kilani-Atmani D., Atmani D. & Isidori M. (2020), Antimutagenic, antigenotoxic and antiproliferative activities of Fraxinus angustifolia Vahl. leaves and stem bark extracts and their phytochemical composition, PLoS ONE 15(4): e0230690.
- Sun M.M., He M., Korthout H., Halima M., Kim H.K., Yan Y., Wijk E. van, Wijk R. van, Guo C.S. & Wang M. (2019), Characterization of ginsenoside extracts by delayed luminescence, high-performance liquid chromatography, and bioactivity tests, Photochemical & Photobiological Sciences 18(5): 1138-1146.
- Hussain R.M.F., Kim H.K., Khurshid M., Akhtar M.T. & Linthorst H.J.M. (2018), Overexpression of AtWRKY50 is correlated with enhanced production of sinapic derivatives in Arabidopsis, Metabolomics 14: 25.
- Kim H.K., Kostidis S. & Choi Y.H. (2018), NMR Analysis of Fecal Samples. In: Giera M. (Ed.), Clinical Metabolomics: Methods and Protocols. Methods in Molecular Biology no. 1730. New York, NY, U.S.A.: Humana Press. 317-328.
- Verpoorte R., Kim H.K. & Choi Y.H. (2018), Synergy: easier to say than to prove, Synergy 7: 34-35.
- Salome Abarca L.F., Pas J. van der, Kim H.K., Uffelen G.A. van., Klinkhamer P.G.L. & Choi Y.H. (2018), Metabolic discrimination of pine resins using multiple analytical platforms, Phytochemistry 155: 37–44.
- Baaij B.M., Kim H.K., Grosser K., Worrich A. & Jong T.J. de. (2018), Slug herbivory on hybrids of the crop Brassica napus and its wild relative B. rapa, Basic and Applied Ecology 31: 52–60.
- Chen G., Escobar-Bravo R., Kim H.K., Leiss K.A. & Klinkhamer P.G.L. (2018), Induced resistance against western flower thrips by the Pseudomonas syringae-derived defense elicitors in tomato, Frontiers in Plant Science 9: 1417.
- Escobar R., Ruijgrok J., Kim H.K., Grosser K., Dam N.M. van, Klinkhamer P.G.L. & Leiss K.A. (2018), Light intensity-mediated induction of Trichome-associated allelochchemicals increases resistance against thrips in tomato, Plant and Cell Physiology 59(12): 2462-2475.
- Kostidis S., Kokova D., Dementeva N., Saltykova I.V., Kim H.K., Choi Y.H. & Mayboroda O.A. (2017), 1H-NMR analysis of feces: new possibilities in the helminthes infections research, BMC Infectious Diseases 17: 275.
- Ralha de Abreu A.C., Coqueiro A., Sultan A.R., Lemmens N., Kim H.K., Verpoorte R., Warmel W.J.B. van, Simões M. & Choi Y.H. (2017), Looking to nature for a new concept in antimicrobial treatments: isoflavonoids from Cytisus striatus as antibiotic adjuvants against MRSA, Scientific Reports 7: 3777.
- Ayouni K., Berboucha M., Kim H.K., Atmani D., Verpoorte R. & Choi Y.H. (2016), Metabolomic tool to identify antioxidant compounds of Fraxinus angustifolia leaf and stem bark extracts, Industrial Crops and Products 88: 65-77.
- Kim H.K., Rutten N.B.M.M., Besseling-van der Vaart I., Niers L.E.M., Choi Y.H., Rijkers G.T. & Hemert S. van (2015), Probiotic supplementation influences faecal short chain fatty acids in infants at high risk for eczema, Beneficial Microbes 6(6): 783-790.
- Khoyratty S., Dupont J., Lacoste S., Palama T.L., Choi Y.H., Kim H.K., Payet B., Grisoni M., Fouillaud M., Verpoorte R. & Kodja H. (2015), Fungal endophytes of Vanilla planifolia across Réunion Island: isolation, distribution and biotransformation, BMC Plant Biology 15: 142.
- Wu C., Kim H.K., Wezel G.P. van & Choi Y.H. (2015), Metabolomics in the natural products field: a gateway to novel antibiotics, Drug Discovery Today: Technologies 13: 11-17.
- Sar S van der., Kim H.K., Meissner A., Verpoorte R. & Choi Y.H. (2013), Nuclear magnetic resonance spectroscopy for plant metabolite profiling. In: Weckwerth W. & Kahl G. (Eds.), The Handbook of Plant Metabolomics. Weinheim: Wiley-VCH. 57-76.
- Pimenta L.P.S., Kim H.K., Verpoorte R. & Choi Y.H. (2013), NMR-based metabolomics: a probe to utilize biodiversity. In: Rössner U. & Dias D.A. (Eds.), Metabolomics Tools for Natural Product Discovery. Methods in Molecular Biology. Totowa, NJ: Humana Press. 117-127.
- Lopez-Gresa M.P., Lison P., Kim H.K., Choi Y.H., Verpoorte R., Rodrigo I., Conejero V. & Bells J.M. (2013), Metabolic fingerprinting of Tomato Mosaic Virus infected Solanum lycopersicum, Journal of Plant Physiology 169(16): 1586-1596.
- Lopez-Gresa M.P., Lison P., Kim H.K., Choi Y.H., Verpoorte R., Rodrigo I., Conejero V. & Belles J.M. (2012), Metabolic fingerprinting of Tomato Mosaic Virus infected Solanum lycopersicum, Journal of Plant Physiology 169: 1586-1596.
- Yuliana N.D., Iqbal M., Jahangir M., Wijaya C.H., Korthout H.A., Kottenhagen M., Kim H.K. & Verpoorte R. (2011), Screening of selected Asian spices for anti obesity-related bioactivities, Food Chemistry 126: 1724-1729.
- Yuliana N.D., Jahangir M., Korthout H.A., Choi Y.H., Kim H.K. & Verpoorte R. (2011), Comprehensive review on herbal medicine for energy intake suppression, Onbekend 12: 499.
- Kim H.K., Choi Y.H. & Verpoorte R. (2011), NMR-based plant metabolomics: where do we stand, where do we go?, Trends in Biotechnology 29: 267.
- Chan W.T., Choi Y.H., Heijden R. van der, Lee M.S., Lin M.K., Kong H., Kim H.K., Verpoorte R., Hankemeier T. & Greef J. van der (2011), Traditional processing strongly affects metabolite composition by hydrolysis in Rehmannia glutinosa Roots, Chemical and pharmaceutical bulletin 59: 546.
- Bonato C., Nieuwenburg E. van, Gudat J., Thon S.M., Kim H.K., Exter M.P. van & Bouwmeester D. (2011), Strain tuning of quantum dot optical transitions via laser-induced surface defects, PHYSICAL REVIEW B 84: 075306.
- Kim H.K., Verpoorte R. & Choi Y.H. (Eds.) (2010), Special Issue of Phytochemical Analysis, Metabolomics in Natural Products: Wiley.
- López-Gresa M.P., Maltese F., Bellés J.M., Conejero V., Kim H.K., Choi Y.H. & Verpoorte R. (2010), Metabolic Response of Tomato Leaves upon Different Plant-pathogen Interactions, Phytochemical Analysis 21: 89-94.
- Abdel-Farid B., Jahangir M., Mustafa N.R., Dam N. van, Kim H.K., Hondel C.A.M.J.J. van den, Choi Y.H. & Verpoorte R. (2010), Glucosinolate Profiling of Brassica rapa in Response to Infection by Leptosphaeria maculans and Fusarium oxysporum, Onbekend 38: 612-620.
- Simoh S., Linthorst H.J.M., Lefeber A.W.M., Erkelens C., Kim H.K., Choi Y.H. & Verpoorte R. (2010), Metabolic changes of Brassica rapa transformed with bacterial isochorismate synthase gene, J. Plant Physiol. 167: 1525-1532.
- Kim H.K. & Verpoorte R. (2010), Sample preparation for plant metabolomics, Phytochemical Analysis 21: 4-13.
- Kim H.K., Choi Y.H. & Verpoorte R. (2010), NMR-based metabolomic analysis of plants, Nature Physics 5: 536-549.
- Kim H.K., Saifullah S.K., Wilson E., Prat Kricun S.D., Meissner A., Goraler S., Deelder A.M., Choi Y.H. & Verpoorte R. (2010), Metabolic classification of South-American Ilex Species by NMR-based metabolomics, Phytochemistry 71: 773-784.
- Kim H.K., Wilson E., Choi Y.H. & Verpoorte R. (2010), Metabolomics: A tool for anticancer leadfinding from natural products, Planta Med. 76: 1094-1102.
- Verpoorte R., Choi Y.H. & Kim H.K. (2010), Metabolomics: what is new?, Onbekend 25: 128-131.
- Shikov A.N., Kundracikova M., Palama T.L., Pozharitskaya O.N., Kosman V.M., Makarov V.G., Galambosi B., Kim H.K., Jang Y.P., Choi Y.H. & Verpoorte R. (2010), Phenolic constituents of Gnaphalium uliginosum, Phytochemistry Letters 3: 45-47.
- Verpoorte R., Choi Y.H. & Kim H.K. (2010), Metabolomics: will it stay?, Phytochemical Analysis 21: 2-3.
- Arany A.M., Jong T.J. de, Kim H.K., Dam N.M. van, Choi Y.H., Mil H.G.J. van, Verpoorte R. & Meijden E. van der (2009), Genotype-environment interactions affect flower and fruit herbivory and plant chemistry of Arabidopsis thaliana in a transplant experiment, Ecological Research 24: 1161-1171.
- Hien Dao T.T., Puig R.C., Kim H.K., Erkelens C., Lefeber A.W., Linthorst H.J.M., Choi Y.H. & Verpoorte R. (2009), Effect of benzothiadiazole on the metabolome of Arabidopsis thaliana, Plant Physiology and Biochemistry 47: 146-152.
- Jahangir M., Abdel-Farid I.B., Kim H.K., Choi Y.H. & Verpoorte R. (2009), Healthy and unhealthy plants: The effect of stress on the metabolism of Brassicaceae, Environm. Exp. Bot. 67: 23-33.
- Dayakar V., Badri N., Quintana N., El Kassis E., Kim H.K., Choi Y.H., Suguyama A., Verpoorte R., Martinoia E., Manter D.K. & Vivanco Jorge M. (2009), An ABC transporter mutation alters in root exudation of phytochemicals that provoke an overhaul of natural soil microbiota, Plant Physiology 151(4): 2006-2017.
- Abdel-Farid I.B., Jahangir M., Hondel C.A.M.J.J. van den, Kim H.K., Choi Y.H. & Verpoorte R. (2009), Fungal infection-induced metabolites in Brassica rapa, Plant Science 176: 608-615.
- Mustafa N.R., Kim H.K., Choi Y.H., Erkelens C., Lefeber A.W.M., Spijksma G., Heijden R. van der & Verpoorte R. (2009), Retrobiosynthetic investigation of salicylic acid production in Catharanthus roseus cell, Phytochemistry 70: 532-539.
- Jahangir M., Kim H.K., Choi Y.H. & Verpoorte R. (2009), Health affecting compounds in Brassicaceae, Compr. Rev. Food Sci. Food Safety 8: 31-43.
- Kooy F. van der, Maltese F., Choi Y.H., Kim H.K. & Verpoorte R. (2009), Quality control of herbal material and phytopharmaceuticals with the use of MS and NMR based metabolic fingerprinting, Planta Med. 75: 763-775.
- Simoh S., Quintana N., Kim H.K., Choi Y.H. & Verpoorte R. (2009), Metabolic changes in Agrobacterium tumefaciens –infected Brassica rapa, J. Plant Physiol. 166: 1005-1014.
- Mustafa N.R., Kim H.K., Choi Y.H. & Verpoorte R. (2009), Metabolic changes of salicylic acid-elicited Catharanthus roseus cell suspension cultures monitored by NMR-based metabolomics, Biotechnol. Lett. 31: 1967-1974.
- Dao T.H.H., Puig R.C., Kim H.K., Erkelens C., Lefeber A.W.M., Linthorst H.J.M., Choi Y.H. & Verpoorte R. (2008), Effect of benzothiadiazole on the metabolome of Arabidopsis thaliana, Plant Physiology and Biochemistry : .
- Mosleh Arany A., Jong T.J. de, Kim H.K., Dam N. van, Choi Y.H., Verpoorte R. & Meijden E. van der (2008), Different chemical composition of plants from dune and inland populations of Arabidopsis thaliana in the Netherlands and their implications for plan-herbivore interactions, Journal of Chemical Ecology : .
- Jahangir M., Kim H.K., Choi Y.H. & Verpoorte R. (2008), Metabolomic response of Brassica rapa submitted to pre-harvest bacterial contamination, Food Chemistry 107: 362-368.
- Abdel-Farid I.B., Choi Y.H., Kim H.K., Hondel C.A.M.J.J. van den, Meijden E. van der & Verpoorte R. (2008), The role of secondary metabolites in Arabidopsis and Brassica in the interaction with fungi, Current Topics in Microbiology and Immunology : .
- Simoh S., Quintana N., Kim H.K., Choi Y.H. & Verpoorte R. (2008), Metabolic changes in Agrobacterium tumefaciens –infected Brassica rapa, Journal of Plant Physiology : .
- Jahangir M., Kim H.K., Choi Y.H. & Verpoorte R. (2008), Health affecting compounds in Brassicaceae, Compr. Rev. Food Sci. Food Safety : .
- Abdel-Farid I.B., Jahangir M., Kim H.K., Choi Y.H. & Verpoorte R. (2008), Fungal infection-induced metabolites in Brassica rapa, Plant Science : .
- Angelova N.S., Kong H.W., Heijden R. van der, Yang S.Y., Choi Y.H., Kim H.K., Wang M., Hankemeier T., Greef J. van der, Xu X. & Verpoorte R. (2008), Recent methodology in the phytochemical analysis of ginseng, Phytochemical Analysis 19: 2-16.
- Mosleh Arany A., Jong T.J. de, Kim H.K., Dam N. van, Choi Y.H., Verpoorte R. & Meijden E. van der (2008), Glucosinolates and other metabolites in leaves of Arabidopsis thaliana from natural populations and their effects on a generalist and a specialist Herbivore, Journal of Chemical Ecology 18: 65-71.
- Mustafa N.K., Kim H.K., Choi Y.H. & Verpoorte R. (2008), Single step purification of salicylic acid from Catharanthus roseus cell culture (plant material) by anion exchange for NMR analysis, Journal of Liquid Chromatography and Related Technologies 31: 702-713.
- Verpoorte R., Choi Y.H., Mustafa N.K. & Kim H.K. (2008), Metabolomics: back to basics, 7: 525-538.
- Abdel-Farid I.B., Jahangir M., Mustafa N.R., Dam N. van, Hondel C.A.M.J.J. van den, Kim H.K., Choi Y.H. & Verpoorte R. (2008), Glucosinolate Profiling of Brassica rapa in Response to Infection by Leptosphaeria maculans and Fusarium oxysporum, Journal of Liquid Chromatography and Related Technologies : .
- Chang W.T., Choi Y.H., Heijden R. van der, Kong H., Kim H.K., Verpoorte R., Xu G., Hankemeier T., Greef J. van der & Wang M. (2008), Traditional processing strongly affects metabolite composition by hydrolysis in Rehmannia glutinosa Roots, : .
- Jahangir M., Bayoumi I., Abdel-Farid I.B., Kim H.K., Choi Y.H. & Verpoorte R. (2008), Stress induced metabolic responses in food plants of Brassicaceae, Mol. Biosystem. : .
- Mustafa N.R., Kim H.K., Choi Y.H., Erkelens C., Lefeber A.W.M., Spijksma G., Heijden R. van der & Verpoorte R. (2008), Retrobiosynthetic investigation of salicylic acid production in Catharanthus roseus cell, Phytochemistry : .
- Kooy F. van der, Maltese F., Choi Y.H., Kim H.K. & Verpoorte R. (2008), Quality control of herbal material and phytopharmaceuticals with the use of MS and NMR based metabolic fingerprinting, Planta Medica : .
- Verpoorte R., Choi Y.H. & Kim H.K. (2007), NMR-based metabolomics at work in phytochemistry, 6: 3-14.
- Sanchez-Sampredo A., Kim H.K., Choi Y.H., Verpoorte R. & Corchete P. (2007), Metabolomic alterations in elicitor treated Silybum marianum suspension cultures monitored by nuclear magnetic resonance spectroscopy, Journal of Biotechnology 130: 133-142.
- Khatib A., Wilson E.G., Kim H.K., Supardi M., Choi Y.H. & Verpoorte R. (2007), NMR assignment of iso--acids from isomerised extracts of Humulus lupulus L. cones, Phytochemical Analysis 18: 371-377.
- Abdel-Farid I.B., Kim H.K., Choi Y.H. & Verpoorte R. (2007), Metabolic characterization of Brasica rapa leaves by NMR-spectroscopy, Journal of Agricultural and Food Chemistry 55: 7936-7943.
- Liang Y.-S., Choi Y.H., Kim H.K., Linthorst H.J.M. & Verpoorte R. (2006), Metabolomic analysis of methyl jasmonate treated Brassica rapa leaves by 2-dimensional NMR spectroscopy, Phytochemistry 67: 2503-2511.
- Mosleh Arany A., Jong T.J. de, Kim H.K., Dam N. van, Choi Y.H., Verpoorte R. & Meijden E. van der (2006), Glucosionaltes and some other chemical compounds in natural populations of Arabidopsis thaliana and their effects on generalist and specialist herbivores, Journal of Chemical Ecology : .
- Liang Y.-S., Lefeber A.W.M., Erkelens C., Kim H.K., Choi Y.H. & Verpoorte R. (2006), Identification of phenylpropanoids in Brassica rapa leaves treated with methyl jasmonate using two-dimensional nuclear magnetic resonance spectroscopy, Journal of Chromatography A 1112: 148-155.
- Khatib A., Kim H.K., Wilson E.G., Choi Y.H. & Verpoorte R. (2006), High performance liquid chromatographic method for iso-alpha-acids, Journal of Liquid Chromatography and Related Technologies 29: 293-302.
- Hendrawati O., Yao Q., Kim H.K., Linthorst H.J.M., Erkelens C., Lefeber A.W.M., Choi Y.H. & Verpoorte R. (2006), Metabolic differentiation of Arabidopsis treated with methyl jasmonate using nuclear magnetic resonance spectroscopy, Plant Science 170: 1118-1124.
- Kim H.K., Choi Y.H. & Verpoorte R. (2006), Metabolomic analysis of Catharanthus roseus using NMR and principal component analysis. Biotechnology. In: Saito K., Dixon R. & Willmitzer L. (Eds.), Agriculture and Forestry. Heidelberg: Springer. 261-276.
- Khatib A., Wilson E.G., Kim H.K., Lefeber A.W.M., Erkelens C., Choi Y.H. & Verpoorte R. (2006), Application of two dimensional J-resolved nuclear magnetic resonance spectrum to differentiation of beer, Analytica Chimica Acta 559: 264-270.
- Choi Y.H., Kim H.K. & Verpoorte R. (2006), Metabolomics. In: Kayser O. & Quax W. (Eds.), Medicinal Plant Biotechnology: From Basic Research to Industrial Applications. Weinheim: Wiley-VCH. 9-28.
- Choi Y.H., Kim H.K., Verpoorte R., Linthorst H.J.M., Hollander J., Lefeber A.W.M., Erkelens C. & Nuzillard J.-M. (2006), NMR metabolomics to revisit the tobacco mosaic virus infection in Nicotiana tabacum leaves, 69: 742-742.
- Liang Y.-S., Choi Y.H., Kim H.K., Linthorst H.J.M. & Verpoorte R. (2006), Metabolomic analysis of methyl jasmonate treated Brassica rapa leaves by two dimensional NMR spectroscopy and multivariate analysis, Phytochemistry 67: 2503-2511.
- Widarto H.T., Meijden E. van der, Lefeber A.W.M., Erkelens C., Kim H.K., Choi Y.H. & Verpoorte R. (2006), Metabolomic differentiation of Brassica rapa following herbivory by different insect instars using two dimensional nuclear magnetic resonance spectroscopy, Journal of Chemical Ecology 32(11): 2417-2428.
- Hendrawati O., Yao Q., Choi Y.H., Kim H.K., Linthorst H.J.M., Erkelens C., Lefeber A.W.M. & Verpoorte R. (2006), Metabolic differentiation of Arabidopsis treated with methyl jasmonate using nuclear magnetic resonance spectroscopy, Plant Science 170: 1118-1124.
- Yang S.Y., Kim H.K., Lefeber A.W.M., Erkelens C., Angelova N.S., Choi Y.H. & Verpoorte R. (2006), Application of Two Dimensional Nuclear Magnetic Resonance Spectroscopy to Quality Control of Ginseng Commercial Products, Planta Medica 72: 364-369.
- Widarto H.T., Meijden E. van der, Lefeber A.W.M., Erkelens C., Kim H.K., Choi Y.H. & Verpoorte R. (2006), Metabolomic differentiation of Brassica rapa leaves attacked by herbivore using two dimensional nuclear magnetic resonance spectroscopy, Journal of Chemical Ecology 32: 2417-2428.
- Choi Y.H., Sertic S., Kim H.K., Wilson E.G., Michopoulosa F., Lefeber A.W.M., Erkelens C., Kricun S.D.P. & Verpoorte R. (2005), Classification of Ilex species based on metabolomic fingerprinting using NMR and multivariate data analysis, Journal of Agricultural and Food Chemistry 53: 1237-1245.
- Verpoorte R., Kim H.K. & Choi Y.H. (2005), Editorial, 100: 53-56.
- Kim H.K., Harrison N., Amitsuka H., Jorge G.A., Jaime M. & Mydosh J.A. (2005), Link between magnetic field-induced quantum criticality and phase formation in U(Ru1-xRhx)xSi2, Physica B: Condensed Matter 359(361): 32-34.
- Kim H.K., Choi Y.H., Erkelens C., Lefeber A.W.M. & Verpoorte R. (2005), Metabolic fingerprinting of Ephedra species using 1H-NMR spectroscopy and principle component analysis, Chemical and pharmaceutical bulletin 53: 105-109.
- Kirk H.E., Choi Y.H., Kim H.K., Verpoorte R. & Meijden E. van der (2005), Comparing metobolomics: the chemical consequences of hybridization in plants, New Phytology : 613-622.
- Verpoorte R., Kim H.K. & Choi Y.H. (2005), New perspectives of medicinal plants in a globalized world. Mukherjee P.K. (Ed.), Proceedings International Conference on Botanicals. . Kolkata, India: Allied Book Agency. 11-18.
- Kirk H.E., Choi Y.H., Kim H.K., Verpoorte R. & Meijden E. van der (2005), Comparing metabolomes: the chemical consequences of hybridization in plants, New Phytology 167: 613-622.
- Choi Y.H., Casas Tapias E., Kim H.K., Lefeber A.W.M., Erkelens C., Verhoeven J.TH.J., Brzin J., Zel J. & Verpoorte R. (2004), Metabolic discrimination of Catharanthus roseus leaves infected by phytoplasma using 1HNMR spectroscopy and multivariate data analysis, 135: 2398-2410.
- Choi Y.H., Kim H.K., Hazekamp A., Erkelens C., Lefeber A.W.M. & Verpoorte R. (2004), Metabolomic Differentiation of Cannabis sativa Cultivars Using 1H-NMR and Principal Component Analysis, J. Nat. Prod. 67: 953-957.
- Choi Y.H., Kim H.K., Wilson E., Erkelens C., Trijzelaar B. & Verpoorte R. (2004), Quantitative analysis of retinol and retinol palmitate in vitamin tablets using 1H-nuclear magnetic resonance spectroscopy, Analytica Chima Acta 512: 141-147.
- Kim H.K., Choi Y.H., Wen-Te Chang R. & Verpoorte R. (2003), Quantitative analysis of ephedrine analogues from Ephedra species using H-1-NMR, Chemical and pharmaceutical bulletin 51: 1382-1385.