Investigations of acetaminophen binding to bovine serum albumin in the presence of fatty acid: Fluorescence and 1H NMR studies

The binding of acetaminophen to bovine serum albumin (BSA) was studied by the quenching fluorescence method and the proton nuclear magnetic resonance technique (1H NMR). For fluorescence measurements 1-anilino-9-naphthalene sulfonate (ANS) hydrophobic probe was used to verify subdomain IIIA as acetaminophen’s likely binding site. Three binding sites of acetaminophen in subdomain IIA of bovine serum albumin were found. Quenching constants calculated by the Stern–Volmer modified method were used to estimate the influence of myristic acid (MYR) on the drug binding to the albumin. The influence of [fatty acid]/[albumin] molar ratios on the affinity of the protein towards acetaminophen was described. Changes of chemical shifts and relaxation times of the drug indicated that the presence of MYR inhibits interaction in the AA–albumin complex. It is suggested that the elevated level of fatty acids does not significantly influence the pharmacokinetics of acetaminophen.