Six novel
ruthenium(II)- and
osmium(II)-arene complexes with three modified indolo[3,2-c]
quinolines have been synthesized in situ starting from 2-aminoindoloquinolines and
2-pyridinecarboxaldehyde in the presence of [M(
p-cymene)Cl(2)](2) (M = Ru, Os) in
ethanol. All complexes have been characterized by elemental analysis, spectroscopic techniques ((1)H, (13)C NMR, IR, UV-vis), and ESI mass spectrometry, while four complexes were investigated by X-ray diffraction. The complexes have been tested for antiproliferative activity in vitro in A549 (non-small cell lung), SW480 (colon), and CH1 (ovarian) human
cancer cell lines and showed IC(50) values between 1.3 and >80 μM. The effects of Ru vs Os and modifications of the
lactam unit on intermolecular interactions, antiproliferative activity, and cell cycle are reported. One
ruthenium complex and its
osmium analogue have been studied for anticancer activity in vivo applied both intraperitoneally and orally against the murine colon
carcinoma model CT-26. Interestingly, the
osmium(II) complex displayed significant growth-inhibitory activity in contrast to its
ruthenium counterpart, providing stimuli for further investigation of this class of compounds as potential
antitumor drugs.