Unveiling the Therapeutic Potential of Organotellurium(IV) Schiff Base Complexes through Structural Elucidation, Antimalarial, Antioxidant and Antimicrobial Studies

Abstract

Infectious diseases have long been a formidable adversary to human health and well-being, presenting a persistent global challenge with far-reaching implication for individuals, communities and societies at large. Thus, with the aim of a combating agent against malarial and oxidant causing ailments, the newly synthesized Organotellurium(IV) complexes with a hydroxynaphthaldehyde Schiff base ligand are proposed in the present research. The structures of the complexes were established through various physical and spectral analysis. The weak electrolytic (8.77 to 35.08 ohm−1 cm2 mol−1) and crystalline nature of the compounds were demonstrated by molar conductivity and TGA, respectively. The ligand and complexes (7a-7f) shows molecular ion peaks at m/z 458.3563, 726.1039, 713.6978, 727.6179, 799.4780, 771.3178 and 799.3978 amu which were well consistent with their formula, revealing formation of compounds. The shifting of ligand's azomethine peak (7.74 ppm) and disappearance of naphthyl hydroxyl proton (12.28 ppm) in 1H NMR spectra confirmed the chelation of ligand with metal ion in proposed manner. In the FT-IR spectra, the complexation of ligand with metal ion was confirmed by disappearance of hydroxyl group (3355 cm−1) band and shifting of C=N (1245 cm−1) and C-O (1632 cm−1) band whereas appearance of Te-O (of 285-293 cm−1) and Te-N (458-467 cm−1) bands, revealed the bonding of metal with metal and octahedral nature of the complexes. Optimized structures, HOMO-LUMO energies and associated chemical reactivity descriptors of the compounds were computed by DFT calculations. The in vitro studies demonstrate that the complexes 7c (1.06 ± 0.11 μM) and 7f (1.22 ± 0.05 μM) exhibited moderate inhibition of the Plasmodium falciparum 3D7 strain, complexes 7a (100.96 ± 0.32 μg/mL) and 7d (96.32 ± 0.40 μg/mL) demonstrated the highest free radical quenching ability. Complex 7c displayed the highest antibacterial actions, whereas 7f exhibited the highest antifungal actions against the tested pathogens. Molecular docking and ADMET studies demonstrated enhanced binding affinity of the complexes compared to the Schiff base and their drug-like qualities.