Multispectral analysis and molecular docking of a zinc (II) complex interaction with bovine serum albumin and studies on antibacterial properties, and catecholase mimicry of the complex

Abstract

This paper presents the synthesis process of a ligand known as 2-(naphthalene-1-yl)-1H-phenanthro[9,10-d]imidazole (NIP) and its metal complex with zinc (II), denoted as FA-128. The structural validation of FA-128 is accomplished through single-crystal X-ray diffraction (XRD). To explore the biological implications, FA-128's interaction with BSA is investigated. This exploration involves fluorescence and UV–vis absorption spectrometry techniques. The outcomes reveal the formation of robust complexes, as FA-128 significantly quenches the inherent fluorescence of BSA. Various aspects are examined, including binding constants, the count of binding sites, thermodynamic parameters, and energy transfer mechanisms. Evident alterations in BSA conformation are detected using synchronous fluorescence and circular dichroism (CD) spectrum techniques. The study proceeds to molecular docking, elucidating binding sites in the FA-128-BSA interaction. Biochemical reactions between metal complexes and proteins often trigger diverse conformational changes in protein structures. This understanding provides crucial insights into the impacts, mechanisms, and systemic transportation of numerous drugs within the body. FA-128 demonstrated superior antibacterial activity against Staphylococcus aureus (ZOI: 10.50 ± 0.50 mm, MIC: 100 μg/mL) and Klebsiella pneumoniae (ZOI: 13.0 ± 0.25 mm, MIC: 50 μg/mL). In addition, FA-128 has been evaluated as a catalytic system in the oxidation of 3,5-di-tert-butylcatechol (3,5DTBC) in a methanol solvent. FA-128 displays good catecholase-like activity with a significant turnover number (k_cat) of 7.56 × 10² h⁻¹, a Michaelis-Menten constant (K_M) of 8.14 × 10⁻⁴ M, and a maximum reaction rate (V_max) of 2.45 × 10⁻⁵ M s⁻¹ under aerobic conditions.