FIGURE 8.
Iron mobilization from an scarcely soluble Fe(III)-oxide as affected by coumarins. (A) Structure-activity relationship of coumarins on Fe mobilization activity. The assays consisted in the incubation of 10 mg of Fe(III)-oxide with a solution of 0 (blank) or 100 μM of the indicated coumarins and 600 μM BPDS at two different pH values, 5.5 and 7.5. Total Fe and Fe(II)-(BPDS)3 in solution were determined by ICP-MS and spectrophotometry, respectively. (B) Effects of the fraxetin concentration on the Fe mobilization activity at pH 7.5. Scatter plot of the concentration of fraxetin vs. the total Fe mobilized and the Fe(II), with linear regression lines in black and their corresponding equations. In all cases (A,B), data are means ± SE (n = 3–12) and asterisks denote a statistically significant difference between blank and a coumarin-containing assay medium as determined by Student’s t- test (p < 0.05).