Synthesis and physicochemical characterizations of coordination between palladium(ii) metal ions with floroquinolone drugs as medicinal model against cancer cells: novel metallopharmaceuticals

Abstract

Three new complexes of palladium(II) floroquinolone drugs (levofloxacin (HLVX), pefloxacin mesylate (HPFX) and lomefloxacin (HLMX)) were prepared in alkaline media at pH = 9. The suggested chemical formula was assigned as [Pd(L)₂] (where L = LVX, PFX and LMX). These complexes were explored by elementary analyses, conductivity tests, infrared and proton NMR spectroscopy, and thermogravimetric analysis and its deferential tools. The homogeneity, surface morphology and particle size of the as-synthesized solid palladium(II) complex were investigated using X-ray powder diffraction and transmittance electron microscopy. FT-IR and ¹H-NMR spectroscopy techniques. The results reveal that HLVX, HPFX and HLMX fluoroquinolones act as bidentate chelates coordinated to the palladium(II) central metal ion via the oxygen of carboxylate and carbonyl groups. The palladium(II) metal ion produces a stable six-membered ring with distorted octahedral structure. The conductivity measurement results deduced that these chelates are non-electrolytic in 1 : 2 stoichiometric ratio. Thermal analysis (TG/DTG) was applied to ascertain the stability of the as-synthesized complexes in comparison to free floroquinolone drugs. The thermal decomposition pathways show that the final residual product is pure PdO. Thermodynamic parameters such as energy of activation E*, entropy ΔS*, enthalpy ΔH* and Gibbs free energy ΔG* of activation were calculated using Coats–Redfern and Horowitz–Metzger non-isothermal techniques. The particle sizes of palladium(II) complexes were measured within nanoscale range, dependent on morphological tools (XRD and TEM). Molecular docking assessment of the three floroquinolones against prostate cancer mutant 2q7k-hormone receptor is discussed. To our knowledge, this paper presents the first-time synthesis and physicochemical characterizations of a coordination complex of palladium(II) metal ions with floroquinolone and its use as a medicinal model against cancer cells.