H-1 NMR determination of hypericin and pseudohypericin in complex natural mixtures by the use of strongly deshielded OH groups (Journal article)

Tatsis, E. C./ Exarchou, V./ Troganis, A. N./ Gerothanassis, I. P.

The H-1 NMR spectra of the commercially available compounds hypericin and its derivative pseudohypericin in CD3OH solutions indicate significantly deshielded signals in the region of 14-15 ppm. These resonances are attributed to the peri hydroxyl protons OH(6), OH(8) and OH(1), OH(13) of hypericins which participate in a strong six-membered ring intramolecular hydrogen bond with CO(7) and CO(14), respectively, and therefore, they are strongly deshielded. In the present work, we demonstrate that one-dimensional H-1 NMR spectra of hypericin and pseudohypericin, in Hypericum perforatum extracts show important differences in the chemical shifts of the hydroxyl groups with excellent resolution in the region of 14-15 ppm. The facile identification and quantification of hypericin and its derivative compound pseudohypericin was achieved, without prior HPLC separation, for two H. perforatum extracts from Greek cultivars and two commercial extracts: a dietary supplement, and an antidepressant medicine. The results were compared with those obtained from UV-vis and LC/MS measurements. (C) 2007 Elsevier B.V. All rights reserved.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
Keywords: h-1 nuclear magnetic resonance,hypericin,pseudohypericin,hypericum perforatum,intramolecular hydrogen bond,peri hydroxyl groups,st-johns-wort,performance liquid-chromatography,magnetic-resonance-spectroscopy,intramolecular hydrogen-bonds,mass-spectrometry,nmr-spectroscopy,quantitative-analysis,qnmr spectroscopy,products analysis,chemical-shifts
URI: https://olympias.lib.uoi.gr/jspui/handle/123456789/8061
ISSN: 0003-2670
Link: <Go to ISI>://000252758000013
Publisher: Elsevier Masson
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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