Investigation of binding interaction between human serum albumin with zirconium complex of curcumin and curcumin

The current study investigates the binding process of Zr(CUR) as a novel six-coordinate complex of zirconium with curcumin ligand and curcumin (CUR); as the main pharmacologically active ingredient of turmeric to human serum albumin (HSA); using fluorescence spectroscopy, infrared spectroscopy and molecular docking techniques. The fluorimetric results revealed that Zr(CUR) and CUR could effectively quench the endogenous fluorescence of HSA, formed a 1:1 complex, with a static quenching mechanism. The distance between donor (HSA) and acceptor (Zr(CUR) and CUR) were determined to be 3.15 nm for Zr(CUR) and 2.95 nm for CUR on the basis of the Forester's theory of non-radiative energy transfer. Results of the infrared absorption spectrum show that the secondary structure of HSA changes for both types. Molecular docking results indicated that for structure with minimum binding energy Zr(CUR) and CUR are in the position between IIA and IIIA. Also, a docking study showed that Zr(CUR) and CUR have several hydrogen bonds and Van der Waals contact with HSA. Communicated by Ramaswamy H. Sarma