BSA binding affinity, free radical scavenging capacity and antibacterial activity of new Silver(I) complexes with Schiff base ligands

In this work, four silver(I) complexes with Schiff bases derived from ninhydrin and selected amino acids (methionine, histidine, cysteine, and phenylalanine) were synthesized. The aim of this study is to determine the potential biological activity of these complexes. FTIR and UV/VIS spectroscopy were used for structural characterization of the products. Antioxidant activity was examined in vitro using DPPH method. Antimicrobial screening was performed by diffusion technique on reference bacterial strains from the ATCC collection. Interaction with bovine serum albumin (BSA) was examined using UV/VIS spectroscopy. Based on the obtained spectral data, it is assumed that all Schiff bases coordinate the Ag(I) ion as a tridentate ONO donor ligand. The antioxidant activity of the synthesized compounds is extremely high, with a range of IC 50 values of 0.023-0.06 mg/mL. Antimicrobial screening determined the inhibitory ability of almost all complexes for concentrations of 1 and 2 mg/mL, with zones of inhibition in the range of 9-19 mm. Examination of the interaction of BSA with Ag(I) complexes revealed the same change in the absorption maximum (hyperchromic shift) in the region of about 205 nm, which indicates that the interaction of BSA and the complex results in conformational changes of BSA.