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Journal of Spectroscopy
Volume 2013, Article ID 749641, 8 pages
http://dx.doi.org/10.1155/2013/749641
Research Article

Demethoxycurcumin-Metal Complexes: Fragmentation and Comparison with Curcumin-Metal Complexes, as Studied by ESI-MS/MS

Adam Mickiewicz University, Faculty of Chemistry, Umultowska 89B, 61-614 Poznań, Poland

Received 23 May 2013; Revised 31 July 2013; Accepted 31 July 2013

Academic Editor: D. Sajan

Copyright © 2013 Wojciech Ostrowski et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Two questions are asked: the first is if the lack/presence of methoxyl moiety at aromatic ring essentially affects the stability of curcuminoid-metal complexes, and the second is if it is possible that in the metal complexes one of the possible demethoxycurcumin structures predominates. To answer the first question, the ESI-MS/MS spectra were taken of ions containing demethoxycurcumin, curcumin, and metal cation (e.g., ion [dCurc + Curc-H + Pb]+), and in order to answer the second question the ESI-MS/MS spectra were recorded of ions containing demethoxycurcumin and metal cation (e.g., ion [dCurc-H + Zn]+). An interpretation of the mass spectra has indicated that (i) for some metals, curcumin-metal complexes are more stable than demethoxycurcumin-metal complexes and for some metals vice versa, and (ii) in demethoxycurcumin-metal complexes structure B1 [(1E,4Z,6E)-5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)hepta-1,4,6-trien-3-one] is more stable than structure B2 [(1E,4Z,6E)-5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl)hepta-1,4,6-trien-3-one].