Coordination Compounds of Platinum and Palladium with Mixed Ligands (Usnic Acid and 1-(o-Tolyl) Biguanide) – Synthesis, Spectral Characterization and Biological Activity

Four coordination compounds of Pd(II), Pt(II) and Pt(IV) with usnic acid (H3AU) and 1-(o-tolyl)biguanide (TB) as ligands have been synthesized in view of their potential as antimicrobial, antifungal and antitumor agents. The metal complexes have been characterized by elemental and thermogravimetrical analyses, infrared and electronic spectra. Based on these studies, the following formulas have been proposed for the complexes: [Pd(TB)(H3AU)]PdCl4 (C1), [Pd(TB)(H2AU)] CH3COO (C2), [Pt(TB)(H2AU)Cl2]Cl (C3) and [Pt(TB)(H2AU)]Cl (C4), where H2AU is deprotonated usnic acid. The in vitro biological activities of the new complexes were tested against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 10231 and HeLa tumor cells. All complexes were found to have good biological properties and therefore they can be further explored in therapeutic applications.