Exploring antidiabetic activity and in silico molecular docking studies of Cu(II) Schiff base complexes

Abstract

A series of Cu(II) complexes [CuLCl], [CuLBr], [CuLNO₃], and [CuLOAc], which have different counter anions, has been synthesised using a tridentate Schiff base, namely 2-(thienylideneamino)benzoic acid (L), to study the effects of the anions on fluorescence and α-amylase inhibitory activity. The spectral data indicate that the ligand moiety was coordinated to the Cu(II) ion through carboxylate (O), azomethine (N), and thiophene (S) atoms. The EPR spectral data suggest a significant covalent character for the Cu-L bond. The fluorescence properties of Cu(II) complexes vary depending on the anions present. As a part of the biological evaluation, antibacterial and α-amylase inhibitory activities of the Schiff base ligand and the Cu(II) complexes have been investigated. The complexes [CuLCl] and [CuLNO₃] exhibited notable antibacterial potential with good minimum inhibitory concentration (MIC) values. From the in vitro α-amylase inhibitory activities, the [CuLNO₃] and [CuLOAc] showed IC₅₀ 0.22 ± 0.019 mg/mL and 0.18 ± 0.015 mg/mL, respectively, which are comparable with the standard drug acarbose with an IC₅₀ of 0.11 ± 0.017 mg/mL. Furthermore, investigations involving the binding interactions of Cu(II) complexes with various enzymes’ active sites, including human pancreatic α-amylase (PDB ID: 4W93), maltase-glucoamylase (PDB ID: 3TOP), and lysosomal acid-α-glucosidase (PDB ID: 5NN8) involved in human glucose hydrolysis have been conducted using molecular docking. CDOCKER interaction energy values of the complexes were quite promising compared to acarbose.