Inactivation of aspirin by metal ions

CHED 859

Regena A. Patterson, tsu_lady18@yahoo.com1, Emanuel A. Waddell, ewaddell@chemistry.uah.edu2, Stephen Schreeves2, and Nsoki Phambu, nphambu@tnstate.edu3. (1) Department of Biology, Tennessee State University, 3500 John A. Merritt Blvd., Nashville, TN 37209, (2) Chemistry, University of Alabama in Huntsville, MSB 203C, John Wright Drive, Huntsville, AL 35899, (3) Department of Chemistry, Tennessee State University, 3500 John A Merritt Blvd, Nashville, TN 37209
Aspirin contains a few potential metal-binding functionalities such as phenyl, acetyl, and carboxylic groups necessary to its analgesic, antipyretic, and anti-inflammatory activities. Since these functional groups are required for its activity, it could be anticipated that aspirin will interact with metal ions present in water or released by antacid preparations. This project examines the effect of metal ions on the structure of aspirin. Complexes of Hg (II), Mg (II), Mn (II), Pb (II), and Zn (II) with aspirin in aqueous solution at different pH values and metal ion concentrations have been investigated using potentiometric titration, infrared and UV visible techniques. The infrared spectra show dramatic changes in the position and intensity of the carboxyl and acetyl bands of aspirin upon metal complexation. The relative stability constants for the binding of aspirin by metal ions were determined by potentiometric titrations. Structural changes were also characterized by Raman and 1H NMR techniques