Synthesis, DNA Binding Studies and Anticancer Properties of Organorhenium Sulfonato Complexes

Abstract

Cancer is a worldwide concern. It is the second leading cause of death in the United States after heart disease and the leading cause of death in many states. The most effective treatments currently being used for cancers are associated with significant side effects and tumor resistance after extended use. Previous studies have described organometallic rhenium complexes as highly promising anticancer compounds since low IC50 values can be obtained and they exhibit low toxicity on normal cells. Other studies have demonstrated strong anticancer activity of Rhenium(V) Oxo complexes against MCF-7 and MDA-MB-231 breast cancer cell lines. In this study, we are exploring the synthesis and anticancer properties of novel rhenium complexes of the type XRe(CO)3Z [X = α-diimines and Z = tosylate, 1-naphthalenesulfonate and 2-naphthalenesulfonate] against breast cancer (hormone-dependent MCF-7, triple-negative MDA-MB-231) and lymphoma cells (U-937). Several derivatives were synthesized in two steps. The first step is the synthesis of a pentylcarbonato (PC) complex from dirhenium decacarbonyl. In the last step, the pentylcarbonato (PC) complex was treated with a corresponding sulfonic acid to afford the expected p-toluenesulfonato (TOS), 1-naphthalenesulfonato (1NS) or 2-naphthalenesulfonato (2NS) complex. These compounds were characterized using IR, NMR, and X-ray crystallography. The sulfonato compounds synthesized had yields ranging from 70¬¬–99%. Alamar blue and MTT cell viability assays were used to determine the IC50 values and demonstrate the potency of the rhenium complexes against breast and lymphoma cells. The complexes were found to be more potent than conventional cancer drug cisplatin. DNA binding studies were performed using UV-Vis titrations, ethidium-bromide displacement assay, cyclic voltammetry, gel electrophoresis, and viscosity. These studies suggested DNA partial intercalation interaction for some of the complexes synthesized.