Re-evaluation of Cytotoxicity and Iron Chelation Activity of Three β-Diketones by Semiempirical Molecular Orbital Method

Abstract

We investigated the chelating effect of FeCl₃ on three β-diketones, curcumin [1], (-)-3-(trifluoroacetyl)camphor [2] and 3-formylchromone [3], as judged by changes in their cytotoxicity and absorption spectra. Addition of an equimolar concentration of FeCl₃ almost completely abrogated the cytotoxicity and changed the pattern of absorption spectra (decrease in the peak height at 430 nm) of [1], without affecting those of [2] and [3]. A semiempirical molecular orbital method (CAChe), based on these experimental data, proposed the estimated structure of [1] chelated with FeCl₃ at 1:1 molar ratio. The present study suggests that [1], but not [2] and [3], is an iron chelator.