Ruthenium(II)-Arene RAPTA Type Complexes Containing Curcunnin and Bisdemethoxycurcumin Display Potent and Selective Anticancer Activity

A series of novel ruthenium(II) arene RAPTA type derivatives (arene = cymene, hexamethylbenzene) containing curcumin-based ligands (curcH = curcumin, bdcurcH = bisdemethoxycurcumin) and PTA (1,3,5-triaza-7-phosphaadamantane) have been synthesized and fully characterized. The solid-state structures of [Ru(cym)(curc)-(PTA)][SO3CF3], [Ru(hmb)(curc)(PTA)] [SO3CF3], and [Ru(hmb)(bdcurc)(PTA)]-[SO3CF3] have been determined by single-crystal X-ray diffraction. The antitumor activity of the complexes has been evaluated in vitro against human ovarian carcinoma cells (A2780 and A2780cisR), as well as against nontumorous human embryonic kidney (HEK293) cells. The correlation of the cytotoxicity upon switching the curcumin-based ligands, i.e. curcumin vs bisdemethoxycurcumin, is not straightforward. In contrast, the PTA ligand greatly enhances the activity and selectivity of ruthenium compounds in comparison to previously reported compounds.