Chemical speciation of metal ion 5-aminosalicylic acid complexesin vivo

AbstractSulfapyridine and 5-aminosalicylate ligands have been studied and formation constants for the latter with protons, zinc, cobaltous, cupric and ferric ions established by potentiometric or spectrophotometric approaches. Such data has been used in chemical speciation models of intestinal fluids to reveal that metal complexes are only weakly present in vivo, that the most bioavailable form is 5-ASAH2 0 potentially entering bacterial cells or the intestinal lining, and that even the most predominant metal ion species, [Cu(5-ASA)H]+ is only present at 3–4% under equilibrium conditions. The metal ions do, however, appear to have an important role in catalysing 5-aminosalicylic acid dissociation.