Antitumor “Saltren” Vanadium(V) Complexes: Synthesis, Characterization and Substitutions Effects

Gilad Nahari, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
Edit Y. Tshuva, The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel

Since the introduction of cisplatin as anticancer agent, many studies focus on identifying additional transition metals complexes for chemotherapeutic applications. A natural candidate for this purpose is vanadium, which is a naturally occurring element with potentially low toxicity; nevertheless, the complex chemistry of vanadium in aqueous solutions challenges the development of antitumor vanadium complexes.

In previous studies[1] our research group introduced isopropoxo vanadium(v) complexes with tetradentate diamino bis(phenolato) “salan” ligands. These complexes showed significant cytotoxic activity but moderate water stability. Additional studies have evinced that labile ligands, while reducing stability are not essential for the cytotoxic activity.

Herein we present a new family of vanadium(v) complexes based on tetramino tris(phenolato) “saltren” ligands. These potentially heptadentate ligands form vanadium(v) complexes with high coordination number and no labile ligands, which is expected to contribute to hydrolysis stability. Several derivatives of these complexes with varying ligand substitutions were synthesized and characterized, some were shown to exhibit marked cytotoxic activity compared to that of cisplatin. The effect of both N- and aromatic substitutions on redox chemistry and reactivity will be discussed.