Identification of phenylpropanoids in methyl jasmonate treated Brassica rapa leaves using two-dimensional nuclear magnetic resonance spectroscopy

• Published in: Journal of Chromatography A Vol. 1112; no. 1; pp. 148 - 155
• Main Authors: Liang, Y.-S., Kim, H.K., Lefeber, A.W.M., Erkelens, C., Choi, Y.H., Verpoorte, R.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 21-04-2006
• Subjects: 5-Hydroxyferuloyl malate; Acetates - pharmacology; Brassica rapa; Brassica rapa - chemistry; Brassica rapa - drug effects; Caffeic Acids - analysis; Caffeic Acids - isolation & purification; Chromatography, High Pressure Liquid - methods; Coumaric Acids - analysis; Coumaric Acids - isolation & purification; Cyclopentanes - pharmacology; Malate-conjugated phenylpropanoids; Malates - analysis; Malates - isolation & purification; Metabolomics; Methyl jasmonate; NMR assignments; Nuclear Magnetic Resonance, Biomolecular - methods; Oxylipins; Phenylpropionates - analysis; Phenylpropionates - isolation & purification; Plant Leaves - chemistry; Plant Leaves - drug effects; Spectrometry, Mass, Electrospray Ionization - methods; Malate-conjugated phenylpropanoids; Metabolomics; Brassica rapa; NMR assignments; 5-Hydroxyferuloyl malate; Methyl jasmonate
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2005.11.114

Metabolic analysis showed a clear increase in phenylpropanoid levels in
Brassica rapa leaves after treatment with methyl jasmonate. A fraction of phenylpropanoids was prepared by Diaion HP-20 and Sephadex LH-20 column chromatography after MeOH-water extraction. Even with these purification steps, isolation of each phenylpropanoid for structure elucidation is not easy due to the low levels in the plants (ca. 0.004%). A mixture was analyzed without further purification using HPLC-electrospray ionization mass spectrometry and NMR spectroscopy. Based on the NMR results including
1H NMR, J-resolved, correlated spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC) spectra, both
1H and
13C resonances of the compounds were obtained. Using these NMR data, five phenylpropanoids conjugated with malate were identified: 5-hydroxyferuloyl-, caffeoyl-, coumaroyl-, feruloyl-, and sinapoyl malate. Of the compounds, 5-hydroxyferuloyl malate is a new phenylpropanoid. In addition to the five constitutive phenylpropanoids bearing
trans-configuration, their
cis forms, which are believed to be artifacts formed in the course of extraction steps, were also identified in the fraction.