Competitive binding of small molecules with biopolymers: a fluorescence spectroscopy and chemometrics study of the interaction of aspirin and ibuprofen with BSA

Abstract

The interaction of aspirin and ibuprofen with bovine serum albumin (BSA) was studied by spectrofluorimetry under simulated physiological conditions. Both aspirin and ibuprofen quenched the intrinsic fluorescence of BSA and the binding ratios obtained were 2 : 1 for aspirin-BSA and 3 : 1 for ibuprofen-BSA interactions, respectively. The thermodynamic parameters (ΔH, ΔS and ΔG) obtained from the fluorescence spectroscopy data showed that the binding of aspirin to BSA involved van der Waals interactions and hydrogen bonds. Competitive experiments using warfarin and diazepam as site markers indicated that aspirin was mainly located in the hydrophobic pocket of site II of the protein as well as to a small extent in site I. Furthermore, the competitive interaction of the aspirin and ibuprofen with BSA, which was studied with the use of the three-way excitation-emission fluorescence spectra and a parallel factor analysis (PARAFAC) chemometrics method, showed that the competitive effect of ibuprofen was stronger than that of aspirin, i.e. the former molecule replaced the aspirin from the aspirin-BSA complex.

Physiological concentrations of albumin favor drug binding

“…5,26 Ni et al showed that the addition of SA to BSA decreases the fluorescence intensity of BSA at 350 nm, and a second peak appears at B410 nm. 5 Fig. 2 shows that the fluorescence intensity of BSA (2 Â 10 À4 mM) decreases upon addition of SA and SLSA at a drug/BSA ratio of 1.…”

“…For example, the intrinsic fluorescence of bovine serum albumin (BSA) was monitored by fluorescence emission spectroscopy in the presence of aspirin. 5 Since aspirin binding or interaction quenches the fluorescence of albumin, fluorescence spectroscopy is used as an indirect method to observe the binding of aspirin to albumin. Similarly, interactions of vitamin C and aspirin with BSA were studied by FTIR to examine the variations in the stability and conformation of BSA.…”

“…1). [5][6][7] Here, we specifically aim at studying in vitro SLSA binding and release profiles of BSA as well as the SLSA capacity of BSA at different albumin concentrations. Dynamics of drugs changes enormously upon protein binding so we can monitor the bound and unbound spin labeled drug in the presence of albumin simultaneously by EPR spectroscopy.…”

A novel method for the study of molecular interaction by using microscale thermophoresis

“…Up to present, a variety of powerful tools have been developed to study biomolecular interactions, such as absorption spectroscopy, circulardichroism [8], fluorescence spectroscopy [9], isothermal titration calorimetry (ITC) [10,11], fluorescence polarization (FP) [12,13], surface plasmon resonance (SPR) [14,15], dynamic light scattering (DLS) [16] and so on. These approaches are useful and convenient for investigating biomolecular interaction, but also have some disadvantages.…”

Binding of enterolactone and enterodiol to human serum albumin: increase of cysteine-34 thiol group reactivity

“…57 Therefore, information about binding of EL and ED to drug site II could be obtained by monitoring the fluorescence changes of FA-free HSA-EL and FA-free HSA-ED after titration with diazepam. As shown in Fig.…”