Effect of Cu2+ and Fe3+ for drug delivery: Decreased binding affinity of ilaprazole to bovine serum albumin

The interaction between ilaprazole and bovine serum albumin (BSA) has been investigated in the absence and presence of Cu2+ or Fe3+ by means of fluorescence spectroscopy. The fluorescence intensity of BSA decreased remarkably with no obvious BSA maximum emission wavelength shift by adding ilaprazole. Similar fluorescence shape with larger quenching extent of BSA was observed with increasing concentrations of ilaprazole in the presence of Cu2+ or Fe3+. The quenching constants and affinities of ilaprazole with BSA in the presence of Cu2+ and Fe3+ decreased. The decreased affinity and unchangeable binding distance in the presence of metal ions may result from a competitive binding between ilaprazole and metal ions. The results indicated that the presence of Cu2+ or Fe3+ could improve ilaprazole's maximum effects, which may have relevant consequence in rationalizing dosage for patients with gastric and duodenal ulcers. (C) 2011 Elsevier B.V. All rights reserved.