Albumin Conjugating Amino Acid Schiff-Base Metal Complexes for Scavenging Superoxide Anion Radical

Superoxide anion radical (O2•−) is a toxic reactive oxygen species (ROS). Schiff-base metal complexes have been widely studied as synthetic antioxidants to scavenge ROS. However, it is toxic and shows poor water solubility. In this work, a kind of novel water-soluble biopolymer/metal complex conjugate (HO-SAM@BSA) was prepared by binding the 4-hydroxy-salicylaldehyde amino acid Schiff-base metal complexes (HO-SAM, M = Cu, Zn, Co) with water-soluble biopolymer bovine serum albumin (BSA). The conjugates were characterized using IR, UV–Vis, circular dichroism spectra (CD), and polyacrylamide gel electrophoresis (PAGE). The results show that the structure of BSA is maintained when the binding rate (nHO-SAM: nBSA) of amino acid Schiff-base metal complexes is 10. In addition, the O2•− scavenging activities of resultant conjugates were determined via nitrobule tetrazolium assay method. After combining HO-SAM into BSA, the poor water-solubility of HO-SAM is improved, and the O2•− scavenging activity of BSA increases dramatically. The conjugation HO-SCCu@BSA displays excellent O2•− scavenging activity. When the EC50 value was 0.10 μmol/L, the analog quantity reached 41 % of natural SOD. Therefore, it can act as a bifunctional mimic of enzyme, which has a great application prospect in antioxidant drug.