Bimetallic bis-Aroyldihydrazone-Isatin Complexes of High O=V(IV) and Low Cu(II) Valent Ions as Effective Biological Reagents for Antimicrobial and Anticancer Assays

Abstract

Due to the versatile bioreactivity of aroyldihydrazone complexes as cost-effective alternatives with different transition metals, two novel bimetallic homo-complexes (VOLph and CuLph) were prepared via the coordination of a terephthalic dihydrazone diisatin ligand (H₂Lph) with VO²⁺ and Cu²⁺ ions, respectively. The structure elucidation was confirmed by alternative spectral methods. Biologically, the H₂Lph ligand and its MLph complexes (M²⁺ = VO²⁺ or Cu²⁺) were investigated as antimicrobial and anticancer agents. Their biochemical activities towards <i>ct</i>DNA (calf thymus DNA) were estimated using measurable titration viscometrically and spectrophotometrically, as well as the gel electrophoresis technique. The growth inhibition of both VOLph and CuLph complexes against microbial and cancer cells was measured, and the inhibition action, MIC, and IC₅₀ were compared to the inhibition action of the free H₂Lph ligand. Both VOLph and CuLph showed remarkable interactive binding with <i>ct</i>DNA compared to the free ligand H₂Lph, based on <i>K</i>_b = 16.31, 16.04 and 12.41 × 10⁷ mol^-1 dm³ and ΔGb≠ = 47.11, -46.89, and -44.05 kJ mol^-1 for VOLph, CuLph, and H₂Lph, respectively, due to the central metal ion (V^IVO and Cu^II ions). VOLph (with a higher oxidation state of the V⁴⁺ ion and oxo-ligand) exhibited enhanced interaction with the <i>ct</i>DNA molecule compared to CuLph, demonstrating the role and type of the central metal ion within the performed electronegative and electrophilic characters.