Binding thermodynamics of Diclofenac and Naproxen with human and bovine serum albumins: A calorimetric and spectroscopic study

Abstract

Serum albumins are ubiquitous proteins able to bind a variety of exogenous and endogenous ligands including hydrophobic pharmaceuticals. Most drugs bind to two very active binding regions located within sub-domains IIA and IIIA of the protein, also known as Sudlow's sites. The drug binding mode of serum albumin provides important pharmacological information and influences drug solubility, efficacy, biological distribution, and excretion. Here, the binding thermodynamics of Diclofenac and Naproxen, two non-steroidal anti-inflammatory drugs (NSAIDs) to bovine and human serum albumins (BSA and HSA, respectively) were studied by isothermal titration calorimetry (ITC), fluorescence spectroscopy and differential scanning calorimetry (DSC). The ITC data show that the binding affinity (K) of Diclofenac to BSA and HSA is on the order of 10 4 M-1 with a binding stoichiometry (n) of 2 drug molecules per protein. Naproxen binding to the two proteins exhibits a different profile with K and n values on the order of 10 6 M-1 and 0.75 for BSA and 10 5 M-1 and 3 for HSA, respectively. The binding of the two drugs to HSA is found to be both enthalpically and entropically favored suggesting the formation of hydrogen bonds and van der Waals hydrophobic effects. Binding of the two drugs to BSA is only enthalpically favored with an unfavorable entropy term. Significant enthalpyentropy compensation phenomena were reported for Diclofenac and Naproxen binding to BSA but not to HSA. Fluorescence quenching data between Diclofenac and the two proteins suggest static collisions and the formation of ground-state protein-drug complexes. The DSC data corroborate the ITC findings and show multiple sequential unfolding events and a strong drug stabilization effect at high drug to protein ratios. Overall, the calorimetric and spectroscopic data provided insights into the nature of these protein-drugs interactions and might offer useful information in future drug discovery studies.

Applicability of capillary electrophoresis‐frontal analysis for displacement studies: Effect of several drugs on l‐tryptophan and lidocaine binding to human serum albumin

“…These results agree with literature information about the binding sites of IBU, CP and TL listed in Section 3.2.1. As was mentioned above, DCF mainly binds to Site I, but an article by Zhang et al also documented the binding of DCF to the narrow part of the pocket in subdomain IB [50,51]. Even though LIDO binds in subdomain IB, no effect of DCF on the LIDO-HSA interaction was observed in this study.…”

In‐depth insight into the methods of plasma protein‐drug interaction studies: Comparison of capillary electrophoresis‐frontal analysis, isothermal titration calorimetry, circular dichroism and equilibrium dialysis

“…A slightly higher result but still in the same concentration order of magnitude was measured for DCF using a CD method, unfortunately this trend could not be confirmed for the HSA‐LIDO pair, since their interaction provided no changes in CD spectrum and so the parameters of this interaction could not be directly evaluated by CD. The K b values for the HSA‐DCF pair are also in good agreement with published results obtained using the same methods as in this study . A slightly higher value was obtained by Vuignier et al.…”

Binding Constants of Clinical Drugs and Other Organic Ligands with Human and Mammalian Serum Albumins

“…There was also a report of the comparable binding degrees of antibiotics to bovine and human plasma [25]. Several works cited in the present dataset [26][27][28][29][30][31][32][33] provided the binding constants of the same compounds to bovine and human albumins, measured at the same conditions. Binding to bovine albumins seems to be a little stronger with the average difference between lgK a values about 0.2.…”

“…dataset [26][27][28][29][30][31][32][33] provided the binding constants of the same compounds to bovine and human albumins, measured at the same conditions. Binding to bovine albumins seems to be a little stronger with the average difference between lgKa values about 0.2.…”

“…It is also possible to show the influence of the laboratory bias which results from the differences in experimental techniques, equipment, models, and other factors from one lab to another. Five literature sources [26,71,[84][85][86] were chosen from the dataset that reported the binding constant values for several different ligands (they are hidden under the numbers 1 to 5). The distributions of the lnKa values binned by The data variability is also caused by many methodological details including those falling beyond consideration in the original reports, as well as systematic and random errors.…”