Scheme showing the dependence of structural modification of isoflavone structure on copper reduction at all tested pH. Arrows show the direction of the more potent compound in the sense of copper reduction. Two-way arrows mean no difference. The exceptions are shown in parenthesis. Daidzein (A) was selected as a reference compound because other structural modifications can be related to it. (B) Ononin, (C) formononetin, (D) cladrin, (E) daidzin, (F) isoformononetin, (G) genistin, (H) genistein, (I) prunetin, and (J) biochanin A.