Characterizing the binding interaction between antimalarial artemether (AMT) and bovine serum albumin (BSA): Spectroscopic and molecular docking methods.

Artemether (AMT), a peroxide sesquiterpenoides, has been widely used as an antimalarial for the treatment of multiple drug-resistant strains of plasmodium falciparum malaria. In this work, the binding interaction of AMT with bovine serum albumin (BSA) under the imitated physiological conditions (pH7.4) was investigated by UV spectroscopy, fluorescence emission spectroscopy, synchronous fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD), three-dimensional fluorescence spectroscopy and molecular docking methods. The experimental results indicated that there was a change in UV absorption of BSA along with a slight red shift of absorption wavelength, indicating that the interaction of AMT with BSA occurred. The intrinsic fluorescence of BSA was quenched by AMT due to the formation of AMT-BSA complex. The number of binding sites (n) and binding constant of AMT-BSA complex were about 1 and 2.63×10(3)M(-1) at 298K, respectively, suggesting that there was stronger binding interaction of AMT with BSA. Based on the analysis of the signs and magnitudes of the free energy change (ΔG(0)), enthalpic change (ΔH(0)) and entropic change (ΔS(0)) in the binding process, it can be concluded that the binding of AMT with BSA was enthalpy-driven process due to |ΔH°|>|TΔS°|. The results of experiment and molecular docking confirmed the main interaction forces between AMT and BSA were van der Waals force. And, there was a slight change in the BSA conformation after binding AMT but BSA still retains its secondary structure α-helicity. However, it had been confirmed that AMT binds on the interface between sub-domain IIA and IIB of BSA.