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

Abstract

For the first time, eugenol, a natural bioactive allylphenol, was introduced into coordination with platinum(II) by replacement of ethylene from Zeise’s salt with eugenol (Eug). The obtained complex, K[PtCl₃(Eug)] (1), was used as the key compound for preparation of the series of trans-[PtCl₂(Eug)(Amine)] (2–11), [PtCl(Eug)(8-O-quinoline)] (12) and [PtCl(Eug)(2-O₂C-quinoline)] (13). The synthesized complexes were characterized by elemental analyses, IR, ¹H NMR, ¹³C NMR, HSQS, HMBC, NOESY, and MS spectra. In 1–13 eugenol coordinates with Pt(II) at ethylenic double bond of the allyl group, the donor N of the amines is in trans-position in comparison with the double bond. A display of the trans-effect on the chemical shift of ¹H and ¹³C was remarked. Seven complexes were tested for cell in vitro cytotoxicity on human cancer cells. Complexes 3 and 12 exhibit high activities on Hep-G2 with IC₅₀ = 3.12 and 5.29 μM; 12 gives high activity against KB, Lu and MCF-7 with IC₅₀ = 0.43, 2.95 and 1.84 μM, respectively. Most of these IC₅₀ are lower than those of cisplatin.

Keywords:

• Platinum complex
• eugenol
• 8-hydroxyquinoline
• trans-effect
• anticancer complex