Half-Sandwich Arene Ruthenium(II) and Osmium(II) Thiosemicarbazone Complexes: Solution Behavior and Antiproliferative Activity
journal contributionposted on 20.02.2018, 19:14 by Anna Gatti, Abraha Habtemariam, Isolda Romero-Canelón, Ji-Inn Song, Bindy Heer, Guy J. Clarkson, Dominga Rogolino, Peter J. Sadler, Mauro Carcelli
We report the synthesis, characterization, and antiproliferative activity of organo-osmium(II) and organo-ruthenium(II) half-sandwich complexes [(η6-p-cym)Os(L)Cl]Cl (1 and 2) and [(η6-p-cym)Ru(L)Cl]Cl (3 and 4), where L = N-(2-hydroxy)-3-methoxybenzylidenethiosemicarbazide (L1) or N-(2,3-dihydroxybenzylidene)-3-phenylthiosemicarbazide (L2), respectively. X-ray crystallography showed that all four complexes possess half-sandwich pseudo-octahedral “three-legged piano-stool” structures, with a neutral N,S-chelating thiosemicarbazone ligand and a terminal chloride occupying three coordination positions. In methanol, E/Z isomerization of the coordinated thiosemicarbazone ligand was observed, while in an aprotic solvent like acetone, partial dissociation of the ligand occurs, reaching complete displacement in a more coordinating solvent like DMSO. In general, the complexes exhibited good activity toward A2780 ovarian, A2780Cis cisplatin-resistant ovarian, A549 lung, HCT116 colon, and PC3 prostate cancer cells. In particular, ruthenium complex 3 does not present cross-resistance with the clinical drug cisplatin in the A2780 human ovarian cancer cell line. The complexes were more active than the free thiosemicarbazone ligands, especially in A549 and HCT116 cells with potency improvements of up to 20-fold between organic ligand L1 and ruthenium complex 1.
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549 lungantiproliferative activityL 1potency improvementsligand L 1PC 3 prostate cancer cellscymterminal chlorideAntiproliferative Activity2780Cis cisplatin-resistantHCT 116 cellsHCT 116 coloncancer cell linethiosemicarbazone ligandsrutheniumX-ray crystallographycoordination positionsthiosemicarbazone ligandSolution Behaviorcomplexdrug cisplatinhalf-sandwichDMSO