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

Five new platinum(II) complexes bearing a eugenol and a quinoline derivative, namely [η 2 ‐4‐allyl‐2‐methoxy‐1‐(propoxycarbonylmethoxy)benzene]‐ trans ‐dichlorido(quinoline‐κ N )platinum(II), [PtCl 2 (C 15 H 20 O 4 )(C 9 H 7 N)], ( 2 ), {η 2 ‐4‐allyl‐2‐methoxy‐1‐[(propan‐2‐yloxy)carbonylmethoxy]benzene}‐ trans ‐dichlorido(quinoline‐κ N )platinum(II), [PtCl 2 (C 15 H 19 O 4 )(C 9 H 7 N)], ( 3 ), [η 2 ‐4‐allyl‐2‐methoxy‐1‐(propoxycarbonylmethoxy)benzene]chlorido(quinolin‐8‐olato‐κ 2 N , O )platinum(II), [Pt(C 9 H 6 NO)Cl(C 15 H 20 O 4 )], ( 4 ), {η 2 ‐4‐allyl‐2‐methoxy‐1‐[(propan‐2‐yloxy)carbonylmethoxy]benzene}chlorido(quinolin‐8‐olato‐κ 2 N , O )platinum(II), [Pt(C 9 H 6 NO)Cl(C 15 H 20 O 4 )], ( 5 ), and [η 2 ‐4‐allyl‐2‐methoxy‐1‐(propoxycarbonylmethoxy)benzene]chlorido(quinolin‐2‐carboxylato‐κ 2 N , O )platinum(II), [Pt(C 10 H 6 NO 2 )Cl(C 15 H 20 O 4 )], ( 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 i PrEug (the propan‐2‐yloxy analogue of PrEug) in ( 3 ) and ( 5 ) coordinate with Pt II 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 IC 50 values of 0.38–29.23 µ M 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 (IC 50 = 0.38–1.99 µ M ) being for complexes ( 4 ) and ( 5 ) bearing a quinolin‐8‐olate ligand.