Does caffeine bind to metal ions?


Kolayli S. , OCAK M., KUCUK M. , ABBASOGLU R.

FOOD CHEMISTRY, vol.84, no.3, pp.383-388, 2004 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 84 Issue: 3
  • Publication Date: 2004
  • Doi Number: 10.1016/s0308-8146(03)00244-9
  • Title of Journal : FOOD CHEMISTRY
  • Page Numbers: pp.383-388
  • Keywords: caffeine, EDTA, ferrozine, iron chelating activity, metal ions, complex formation, binding constant, BONE-MINERAL DENSITY, CALCIUM, ZINC, TEA, PHOSPHORUS, COPPER, IRON, CONSUMPTION, METABOLISM, MAGNESIUM

Abstract

The complex formation capacity of caffeine, a highly-consumed tea and coffee component, was determined for Ca, Mg, Fe, Zn, Pb, Mn, Co and Cr metal ions. The binding constants of metal ion-caffeine complexes for the metals chosen were determined spectrophotometrically. The results were compared with the known stability constants of metal ion-EDTA complexes, EDTA being known for its high metal binding capacity. Furthermore, iron chelating activity of caffeine, using the ferrozine reference method, was studied and compared with that of EDTA. The results showed very little complex formation capacity of caffeine with binding constants of 29.6, 22.4. 59, 396, 55, 9.3, 83 and 592 M-1 for Ca, Mg, Fe, Zn, Pb, Mn, Co and Cr metal ions, respectively, in contrast to that of EDTA. The iron chelating activity of caffeine was also found to be 6%, which was considered to be quite low compared with EDTA. (C) 2003 Elsevier Ltd. All rights reserved.