Structural,physicochemical and in vitro pharmacological properties of the stimulant drug 8-chlorotheophylline complexed with Cr(III), Mn(II), Co(II), and Ni(II) metal ions: Potent metallodrug complexes as antimicrobial agents

The interactions of methylxanthine bases with metal ions are of major biological interest and are important in bioinorganic chemistry. One of these bases is 8-chlorotheophylline (Ctp), which exhibits high stimulant action. Here, the metal complexation reactions of Ctp with Cr(III), Mn(II), Co(II), Ni(II), and Cu(II) ions were investigated, in a 1:2 molar ratio and in basic media. All of the prepared complexes were confirmed using elemental analysis, magnetic moment measurements, molar conductance, thermal analysis, and UV–Vis., IR, and Raman spectroscopies. Spectroscopic results revealed direct cation interactions for all of the metal ions via the deprotonated N7 atom of Ctp. The biological activity of the complexes was examined to determine the effect of chelation on the bioactivity of Ctp. It was observed that free Ctp possesses very low inhibitory activity towards several bacteria and fungi. However, the potency of its Cr(III)-complex exceeded that of the standard drug Ciprofloxacin against all of the tested bacterial strains, and the potency of this complex was 28% and 11% higher than those of the standard drug Fluconazole against the Aspergillus flavus and Penicillium Sp fungal strains, respectively.