Synthesis, structure and in vitro cytotoxicity of platinum(II) complexes containing eugenol and a quinolin‐8‐ol‐derived chelator

The synthesis of potassium (η2‐4‐allyl‐2‐methoxyphenol)trichloridoplatinate(II), K[PtCl3(C10H12O2)], (1), starting from Zeise's salt and Ocimum sanctum L. oil has been optimized. Starting from (1), three new platinum(II) complexes, namely (η2‐4‐allyl‐2‐methoxyphenol)chlorido(2‐methylquinolin‐8‐olato‐κ2N,O)platinum(II), (2), (η2‐4‐allyl‐2‐methoxyphenol)chlorido(5‐nitroquinolin‐8‐olato‐κ2N,O)platinum(II), (3), and (η2‐4‐allyl‐2‐methoxyphenol)chlorido(5,7‐dichloroquinolin‐8‐olato‐κ2N,O)platinum(II), [Pt(C9H4Cl2NO)Cl(C10H12O2)], (4), containing eugenol and a quinolin‐8‐ol derivative (R‐OQ), have been synthesized and characterized by elemental analyses, MS, IR, 1H NMR and NOESY spectra. For (1) and (4), single‐crystal X‐ray diffraction studies were also carried out. Complexes (2)–(4) show good inhibiting abilities on three human cancer cell lines, i.e. KB, Hep‐G2 and LU, with IC50 values of 1.42–17.8 µM. Complex (3) gives an impressively high activity against KB, Hep‐G2, LU and MCF‐7, with IC50 values of 1.42–4.91 µM, which are much lower than those of cisplatin and some other platinum(II) complexes. Three new platinum(II) complexes of the type [PtCl(R‐OQ)(Eug)], containing eugenol (Eug) and a quinolin‐8‐ol derivative (R‐OQ), show promising in vitro cytotoxicity on four human cancer cell lines.