Osmium(VI) nitrido complexes bearing azole heterocycles: a new class of antitumor agents

Eight new nitridoosmium(VI) complexes with the general formula [Os-VI(N)Cl-3(Hazole)(2)] have been synthesized and characterized. The cellular uptake and the antiproliferative activities of these compounds against a panel of human cancer cell lines have been investigated. Complexes with pyrazole derivatives (1, 2, 3 and 4) are found to possess significant in vitro cytotoxicity. Further studies of compounds 1 and 3 indicate that they induce S phase arrest in HeLa cells followed by apoptosis, possibly as a result of binding with DNA.