Exploring the antimalarial, antioxidant and antimicrobial properties of newly synthesized diorganotin(IV) complexes with ONO-donor hydrazone ligands

Inspired by the role of organotin(IV) compounds as potential pharmaceutical agents, we have synthesized a series of new diorganotin(IV) complexes (5–20) of hydrazone ligands (1–4) derived from 2-chlorophenoxyacetic hydrazide and salicylaldehyde derivatives. Numerous techniques such as FT-IR, UV–Vis, (1H, 13C, 119Sn) NMR, mass spectrometry, powder XRD, SEM, EDAX, TGA and molar conductance were used to elucidate the structure of the synthesized compounds. These techniques ascertain that the hydrazone ligands coupled with diorganotin(IV) in a tridentate manner via imine nitrogen, phenolic oxygen atom and deprotonated hydroxyl group generating pentacoordinated geometry of the complexes. The low molar conductance values of synthesized compounds indicated their non-electrolytic nature. SnO2 was the final product formed as a result of the thermal breakdown of complexes which suggested the thermal stability of the complexes up to about 176°C. In vitro antimalarial (P.falciparum) activity was performed using microassay protocol which advocated for the higher potency of complexes 16, 20 (IC50 = 0.62–0.67 µM). The antioxidant activity also supported the results of antimalarial data suggesting 16, 20 complexes as active compounds. In vitro, the antimicrobial potential of the compounds has been tested against six pathogens including four bacterial and two fungal strains by serial dilution assay taking ciprofloxacin and fluconazole as reference drugs. Among the synthesized compounds, complexes 8 and 12 (MIC value = 0.0048, 0.0045 µmol/mL) exhibited superior activity. Additionally, the compounds were subjected to in silico ADME analysis suggesting that the compounds can be employed as orally active drugs.