Investigation of the effects of Zn2+, Ca2+ and Na+ ions on the interaction between zonisamide and human serum albumin (HSA) by spectroscopic methods

• Metal ions affect the interaction of clinical drugs with HSA.
• Fluorescence data showed that the quenching processes were stronger in the presence of metal ions.
• Secondary structure of HS changes in the presence of ZNS with and without Zn2+, Ca2+ and Na+.

In this work, The effect of three metal ions Zn2+, Ca2+ and Na1+ on the interaction between human serum albumin (HSA) and zonisamide (ZNS) was investigated employing fluorescence, ultraviolet–visible (UV–Vis) absorption and circular dichroism (CD) under simulated physiological conditions. Fluorescence spectroscopy revealed that these metallic ions and ZNS can quench the HSA fluorescence, and this quenching effect became more significant when both ion and drug are present together. It was found that the quenching mechanism is a combination of static quenching with nonradiative energy transfer. The binding sites number (n), the binding constant (Kb) and the spatial-distance (r) of ZNS with HSA without or with Zn2+, Ca2+ and Na1+ ions were calculated. The presence of Ca2+ and Na+ ions decreased the binding constants (Kb) and the number of binding sites (n) of ZNS–HSA complex. However, the presence of Zn2+ increased the affinity of ZNS for HSA largely. Changes in UV–Vis absorption and CD data are due to the microenvironment of amide moieties in HSA molecules.

In this work, the effects of three metal ions Zn2+, Ca2+ and Na+ on the interaction between human serum albumin (HSA) and zonisamide (ZNS) was investigated.Figure optionsDownload as PowerPoint slide