DIETARY FLAVONOIDS INTERACT WITH TRACE-METALS AND AFFECT METALLOTHIONEIN LEVEL IN HUMAN INTESTINAL-CELLS

Flavonoids are natural compounds found in food items of plant origin. The study examined systematically the interaction of structurally dive rse dietary flavonoids with trace metal ions and the potential impact of dietary flavonoids on the function of intestinal cells. Spectrum an alysis was first performed to determine flavonoid-metal interaction in the buffer. Among the flavonoids tested, genistein, biochanin-A, nari ngin, and naringenin did not interact with any metal ions tested. Memb ers of the flavonol family, quercetin, rutin, kaempferol, flavanol, an d catechin, were found to interact with Cu(II) and Fe(III). On prolong ed exposure, quercetin also interacted with Mn(II). Quercetin at 1:1 r atio to Cu(II) completely blocked the Cu-dependent color formation fro m hematoxylin. When quercetin was added to the growth medium of cultur ed human intestinal cells, Caco-2, the level of metal binding antioxid ant protein, metallothionein, decreased. The effect of quercetin on me tallothionein was dose- and time-dependent. Genistein and biochanin A, on the contrary, increased the level of metallothionein. The interact ion between dietary flavonoids and trace minerals and the effect of fl avonoids on metallothionein level imply that flavonoids may affect met al homeostasis and cellular oxidative status in a structure-specific f ashion.