Mixed natural arylolefin–quinoline platinum(II) complexes: synthesis, structural characterization and in vitro cytotoxicity studies

Abstract

Five new platinum(II) complexes bearing a eugenol and a quinoline derivative, namely [η2-4-allyl-2-methoxy-1-(propoxycarbonylmethoxy)benzene]-trans-dichlorido(quinoline-κN)platinum(II), [PtCl2(C15H20O4)(C9H7N)], (2), {η2-4-allyl-2-methoxy-1-[(propan-2-yloxy)carbonylmethoxy]benzene}-trans-dichlorido(quinoline-κN)platinum(II), [PtCl2(C15H19O4)(C9H7N)], (3), [η2-4-allyl-2-methoxy-1-(propoxycarbonylmethoxy)benzene]chlorido(quinolin-8-olato-κ2 N,O)platinum(II), [Pt(C9H6NO)Cl(C15H20O4)], (4), {η2-4-allyl-2-methoxy-1-[(propan-2-yloxy)carbonylmethoxy]benzene}chlorido(quinolin-8-olato-κ2 N,O)platinum(II), [Pt(C9H6NO)Cl(C15H20O4)], (5), and [η2-4-allyl-2-methoxy-1-(propoxycarbonylmethoxy)benzene]chlorido(quinolin-2-carboxylato-κ2 N,O)platinum(II), [Pt(C10H6NO2)Cl(C15H20O4)], (6), have been synthesized and fully characterized spectroscopically. A single-crystal X-ray diffraction study was carried out for complexes (2) and (4)–(6). PrEug [or 4-allyl-2-methoxy-1-(propoxycarbonylmethoxy)benzene] in (2), (4) and (6), and iPrEug (the propan-2-yloxy analogue of PrEug) in (3) and (5) coordinate with PtII at the ethylenic double bond of the allyl group. In (2)–(6), the donor N atom of the amine group occupies a trans position with respect to the double bond. A comparison of the IC50 values of 0.38–29.23 µM for (2)–(6) with cisplatin, as well as other platinum(II) complexes, indicates an excellent in vitro cytotoxicity against the KB, LU, Hep-G2 and MCF-7 cancer cell lines, with the highest cytotoxic effect (IC50 = 0.38–1.99 µM) being for complexes (4) and (5) bearing a quinolin-8-olate ligand.