The development of novel biologically active organometallic compounds bearing an acetylsalicylic acid (ASA) substructure led to the synthesis of analogical Zeise-type salts that accordingly inhibit cyclooxygenase (COX) enzymes. In order to determine the influence of the length of the alkyl chain between the platinum(II) center and the ASA moiety, compounds with varying methylene groups (n = 1⁻4) were synthesized and characterized. For the propene derivative structural elucidation by X-ray crystallography was possible. Prior to evaluation of biological activity, the complexes were investigated regarding their stability in different media, such as water, physiological sodium chloride, and phosphate buffered saline. Therefore, an analytical method based on capillary electrophoresis was established. All of the compounds were tested for their COX inhibitory potential. In general, complexes with longer alkyl chains caused higher inhibition of COX enzymes and the inhibitory potential towards COX enzymes was enhanced when compared to Zeise's salt. The growth inhibitory effects of the synthesized substances were investigated in vitro against colon carcinoma (HT-29) and breast cancer (MCF-7) cells. The IC50 values of the new derivatives ranged from 30 to 50 µM, whereas neither Zeise's salt itself nor ASA showed any antiproliferative activity at the used concentrations.
Keywords: COX inhibition; Zeise’s salt; anticancer; antiproliferative activity; capillary electrophoresis; cyclooxygenase enzyme; platinum chemistry.