4.4. Detection of Cu(II) Reduction

The selective sequestering agent bathocuproine was employed to detect reduction of Cu(II) to Cu(I) by recording the formation of bathocuproine-Cu(I) complex which absorbs maximally at 480 nm. The reaction mixture (3.0 mL) contained 3.0 mM Tris-HCl (pH 7.5), fixed concentrations (100 µM) of Cu(II) and Cu(I) (for positive control), bathocuproine (300 µM) and of catechins (C, EC, EGC and EGCG) (50 µM). The reaction was started by adding Cu(II) and the spectra were recorded immediately afterwards.