Synthesis and spectral characterization of platinum(II) complexes containing eugenol, a natural allylphenol

Crystal structures of three platinacyclic complexes bearing isopropyl eugenoxyacetate and pyridine derivatives

Three new platinum(II) complexes bearing a eugenol and a pyridine derivative, namely (η2-2-allyl-4-meth-oxy-5-{[(propan-2-yl-oxy)carbon-yl]meth-oxy}phenyl-κC 1)chlorido-(pyridine-κN)platinum(II), [Pt(C15H19O4)Cl(C5H5N)], (I), (η2-2-allyl-4-meth-oxy-5-{[(propan-2-yl-oxy)carbon-yl]meth-oxy}phenyl-κC 1)chlorido-(4-methyl-pyridine-κN)platinum(II), [Pt(C15H19O4)Cl(C6H7N)], (II), and (η2-2-allyl-4-meth-oxy-5-{[(propan-2-yl-oxy)carbon-yl]meth-oxy}phenyl-κC 1)chlorido(pyridine-4-carb-oxy-lic acid-κN)platinum(II), [Pt(C15H19O4)Cl(C6H5NO2)], (III), have been synthesized and further characterized by single-crystal X-ray diffraction. The PtII atoms exhibit the usual distorted square-planar coordination and are surrounded by one Cl atom, one N atom, and a C atom and C=C double bond of the eugenol ligand. The donor N atom of the pyridine ligand occupies a cis position with respect to the double bond. Complexes (I) and (II) crystallize isomorphously in space group P and display a similar crystal packing characterized by C-H⋯O hydrogen bonding, C-H⋯π and π-π inter-actions. However, the presence of the additional methyl group in the 4-methyl-pyridine ligand in (II) disturbs the π-π inter-actions. The crystal packing of (III) is characterized by O-H⋯O hydrogen bonding, resulting in the formation of chains of mol-ecules connected in a head-to-tail fashion and running in the [101] direction. The IC50 values for the HepG2 and KB cell lines are 150.9, 122.3 µM for (I) and 138.9, 93.2 µM for (II), respectively.

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 [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-κ²N,O)platinum(II), [Pt(C₉H₆NO)Cl(C₁₅H₂₀O₄)], (4), {η²-4-allyl-2-methoxy-1-[(propan-2-yloxy)carbonylmethoxy]benzene}chlorido(quinolin-8-olato-κ²N,O)platinum(II), [Pt(C₉H₆NO)Cl(C₁₅H₂₀O₄)], (5), and [η²-4-allyl-2-methoxy-1-(propoxycarbonylmethoxy)benzene]chlorido(quinolin-2-carboxylato-κ²N,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 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 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.

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-κ2 N,O)platinum(II), (2), (η2-4-allyl-2-methoxyphenol)chlorido(5-nitroquinolin-8-olato-κ2 N,O)platinum(II), (3), and (η2-4-allyl-2-methoxyphenol)chlorido(5,7-dichloroquinolin-8-olato-κ2 N,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.