New platinum(II) complexes of CCC-pincer N-heterocyclic carbene ligand: Synthesis, characterization, cytotoxicity and antileishmanial activity

• Five CCC-pincer N-heterocyclic carbene Pt(II) complexes synthesized and characterized.
• The antileishmanial activity of carbene Pt(II) complexes were investigated.
• Evaluation of cytotoxic activity of carbene Pt(II) complexes carried out.

Five new CCC-pincer N-heterocyclic carbene Pt(II) complexes, [Pt(TMPCCC)X] (X = Cl (1), O2C(CH3) (2), O2C(CH2CH3) (3), O2C(CH2CH2CH3) (4), O2C(CH(CH3)2) (5)) (TMPCCC = 1,1′-(1,3-phenylene)bis(3-(2,4,6-trimethoxyphenyl)-1H-benzo[d]imidazol-2-ylidene) were synthesized and characterized by elemental analysis, IR, (13C, 1H) NMR and ESI-MS spectroscopies. Complexes 1–5 showed varying degree of antileishmanial activities with IC50 values ranging between 0.02 and 3.41 μM. Complex 5 significantly showed the best antiproliferative activity against Leishmania species essayed more active than the reference drug amphotericin B. The antiproliferative effects of 1-5 were assessed on a panel of four human tumor cell lines including human ovarian (SKOV3, inherently resistant to cisplatin), human breast cancer (MCF-7), human colon adenocarcinoma (HT29) and lung adenocarcinoma (A549) cells. Complex 5 was 16 times as cytotoxic as cisplatin in the same cell line.

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