H-1 NMR determination of hypericin and pseudohypericin in complex natural mixtures by the use of strongly deshielded OH groups
| Autor: | Tatsis, E. C., Exarchou, V., Troganis, A. N., Gerothanassis, I. P. |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2008 |
| Předmět: |
performance liquid-chromatography
pseudohypericin products analysis intramolecular hydrogen bond mass-spectrometry intramolecular hydrogen-bonds h-1 nuclear magnetic resonance quantitative-analysis hypericum perforatum nmr-spectroscopy magnetic-resonance-spectroscopy qnmr spectroscopy chemical-shifts st-johns-wort hypericin peri hydroxyl groups |
| Popis: | 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. Analytica Chimica Acta |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|