Exploring the Versatility of Cycloplatinated Thiosemicarbazones as Antitumor and Antiparasitic Agents

Tridentate cycloplatinated thiosemicarbazone complexes
have been
prepared from a biologically significant ligand, 3,4-dichloroacetophenone
thiosemicarbazone (1). The tetranuclear complex 2 was prepared by reaction of the ligand with K2[PtCl4]. Two mononuclear (3 and 4) and two dinuclear (5 and 6) complexes
were isolated upon cleavage of the Pt–Sbridging bonds
of the tetranuclear complex 2 with the appropriate phosphane
ligand. Each complex was characterized using various analytical and
spectroscopic techniques, and the molecular structures of 2–4 were also elucidated. The in vitro antiparasitic activities of these complexes against Plasmodium falciparum strains (D10 (chloroquine sensitive)
and Dd2 (chloroquine resistant)) and Trichomonas vaginalis have been determined. Preliminary studies into their potential plasmodial
target in the form of β-hematin formation inhibition assays
were also completed. Preliminary results suggest that ligand 1 and complex 3 do not hinder formation of β-hematin.
The antiproliferative activity of the complexes against the cisplatin-senstive
A2780 and cisplatin-resistant A2780cisR human ovarian cancer cell
lines has been evaluated. The complexes were found to exhibit moderate
to weak inhibitory activities.