Design, spectroscopic properties and effects of novel catechol spiroborates derived from Schiff bases in the antioxidant, antibacterial and DNA binding activity

Novel catechol spiroborates (L(1–5)B) were prepared from the reaction of the corresponding Schiff base (L(1–5)H) ligands, boric acid, and 3,5-di‑tert‑butyl catechol under favorable reaction conditions. The synthesized all compounds were characterized by NMR spectra, FT-IR spectra, UV-Vis spectra, LC-MS/MS spectra, fluorescence spectra, elemental analysis as well as the melting point. The optical properties of the Schiff base ligands and catechol spiroborates were investigated using – and fluorescence spectra in the C2H5OH. The antioxidant activities of newly synthesized Schiff base ligands and their catechol spiroborates were investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability and reducing power ability. Among the synthesized catechol spiroborates, (L2B) exhibited the maximum radical scavenging (91.5 ± 2.11%) and reducing power activity (0.654±0.015) at a concentration of 200.0 µg/mL. Antibacterial activity was determined using 3 Gram positive and 2 Gram negative bacteria by disk diffusion method. Schiff base (L2H) was found to be effective against all test bacteria used. Besides, the DNA binding activity of the catechol spiroborates was determined using Calf Thymus DNA, and the DNA cleavage activity was determined using pBR-322 plasmid DNA by agarose gel electrophoresis method.