Synthesis and Therapeutic Potential of selected Schiff Bases: In vitro Antibacterial, Antioxidant, Antidiabetic, and Computational Studies

In this study, three Schiff base compounds, (E)-N-(4-bromophenyl)-1-(2-nitrophenyl)methanimine (L-1), (E)-2-((mesitylimino)methyl)phenol (L-2), and (E)-N-(4-bromophenyl)-1-(pyridin-2-yl)methanimine (L-3), were synthesized and characterized by various spectroscopic techniques. The antibacterial activity of the compounds was evaluated against Gram-positive and Gram-negative bacteria, with L-3 demonstrating the most significant activity. The compounds were also evaluated for their antioxidant activity using DPPH, FRAP, and NO scavenging assays. While the compounds exhibited concentration-dependent scavenging of free radicals, their activity was not as significant as that of the reference, Trolox. Furthermore, L-1-L-3 were tested for their alpha-amylase and alpha-glucosidase inhibitory activity, with L-1 showing the highest inhibitory activity among the three compounds. The DFT study showed that L-1 is the most chemically reactive among the three compounds, having the lowest energy band gap value of 3.82 eV in acetonitrile, the experimental solvent. Molecular docking predicted that L-1 and L-2 have very strong inhibition equivalents to the standard drugs against bacteria and diabetes. All the compounds showed stronger inhibition against alpha-glucosidase than acarbose, while only L-1 and L-2 exhibited stronger inhibition against alpha-amylase than acarbose. It can be deduced that the theoretical studies corroborate well with the experimental, and compounds with the electron-withdrawing group displayed better medicinal properties than their electron-donating counterparts.