Investigation of binding properties of dicationic styrylimidazo[1,2‐a]pyridinium dyes to human serum albumin by spectroscopic techniques

Abstract

The binding interaction between two dicationic styrylimidazo[1,2-a]pyridinium dyes and human serum albumin (HSA) was investigated at physiological conditions using fluorescence, UV-vis absorption, and circular dichroism (CD) spectroscopies. Analysis of the fluorescence titration data at different temperatures suggested that the fluorescence quenching mechanism of HSA by these dyes was static. The calculated thermodynamic parameters (ΔG°, ΔH° and ΔS°) indicated that hydrogen bonding and van der Waals forces played a major role in the formation of the dye-HSA complex. Binding distances (r) between dyes and HSA were calculated according to Förster's non-radiative energy transfer theory. Studies of conformational changes of HSA using CD measurements indicate that the α-helical content of the protein decreased upon binding of the dyes. Copyright © 2016 John Wiley & Sons, Ltd.

Binding of the anticancer drug BI-2536 to human serum albumin. A spectroscopic and theoretical study

“…shows a strong affinity to HSA (Ka c = 3.78×10 6 ; Ka u = 1.14×10 9 at 310 K) in comparison with the published binding constants of drugs which bind to site I such as warfarin (Ka u = 6.17×10 4 at 310 K) [52], tenofovir (Ka u = 5.70×10 4 at 310 K) [51], dexamethasone (Ka u = 7.1×10 3 at 308 K) and furosemide (Ka c = 1.99×10 5 at 310 K) [53]. Affinities to HSA comparable to that of BI-2536 were found for two members of the imidazo[1,2-a]pyridine family, with different known pharmaceutical applications (Ka c = 1.69×10 6 -4.28×10 6 at 310 K) [54]. Both those compounds and BI-2536 show a certain structural similarity, as they are extended molecules with several aromatic rings.…”