Synthesis, characterization, cytotoxicity, and DNA binding of some new platinum(II) and platinum(IV) complexes with benzimidazole ligands

Figures & data

Scheme 1.  Synthesis of carrier ligand and Pt(II) and Pt(IV) complexes.

Table 1.  IC₅₀ (μM) values of Pt(II) and Pt(IV) complexes on selected human tumor cell lines.

Compound	IC50 (μM)
	MCF-7	HeLa	HEp-2
1	18.8 ± 3.4	39.5 ± 1.7	1.3 ± 0.4
2	>100	41.8 ± 2.0	>100
3	>100	>100	7.2 ± 1.9
4	41.9 ± 4.0	22.5 ± 3.0	14.6 ± 3.5
5	>100	20.7 ± 3.8	>100
Cisplatin	3.5 ± 1.1	1.3 ± 0.3	15.8 ± 2.0
Carboplatin	27.5 ± 2.6	14.8 ± 4.4	>100

Figure 1.  Electrophoretograms relating to the interaction of pBR322 plasmid DNA with increasing concentration of cisplatin and 1–5. Lane 1 in both electrophoretograms contains untreated pBR322 plasmid DNA to serve as a control. For cisplatin, lane 2: 0.625 µM, lane 3: 1.25 µM, lane 4: 2.5 µM, lane 5: 5 µM, lane 6: 10 µM. For 1–5, lane 2: 0.625 µM, lane 3: 1.25 µM, lane 4: 2.5 µM, lane 5: 5 µM, lane 6: 10 µM, lane 7: 20 µM, lane 8: 40 µM, lane 9: 80 µM, lane 10: 160 µM. Roman numerals I and II indicate form I (covalently closed circular) and form II (open circular) plasmids, respectively.

Figure 2.  Electrophoretograms relating to the incubated mixtures of pBR322 plasmid DNA and increasing concentration of cisplatin and 1–5 followed by BamH1 digestion. For both cisplatin and 1–5, lane 1 is untreated and undigested with BamH1, lane 2 is untreated pBR322 plasmid DNA but digested with BamH1. For cisplatin, lane 3: 0.625 µM, lane 4: 1.25 µM, lane 5: 2.5 µM, lane 6: 5 µM, lane 7: 10 µM, lane 8: 20 µM. For 1–5, lane 3: 0.625 µM, lane 4: 1.25 µM, lane 5: 2.5 µM, lane 6: 5 µM, lane 7: 10 µM, lane 8: 20 µM, lane 9: 40 µM, lane 10: 80 µM, lane 11: 160 µM. Roman numerals I, II, and III indicate form I (covalently closed circular), form II (open circular), and form III (linear) plasmids, respectively.