Biological investigation of the platinum(II)-[*I]iodohistamine complexes of potential synergistic anti-cancer activity

Photophysicochemical behavior and antimicrobial activity of dihydroxosilicon tris(diaquaplatinum)octacarboxyphthalocyanine

Platination of dihydroxosilicon octacarboxyphthalocyanine (OH)2SiOCPc was successfully carried out to give dihydroxosilicon tris(diaquaplatinum)octacarboxyphthalocyanine (OH)2SiOCPc(Pt)3 conjugate. Slight blue shifting of the absorption spectrum of (OH)2SiOCPc(Pt)3 was observed on conjugation with platinum. Comparative photophysicochemical behavior and antimicrobial photo-activities of (OH)2SiOCPc(Pt)3 conjugate with (OH)2SiOCPc or Pt nanoparticles revealed that the heavy atom, Pt on the periphery of the phthalocyanine significantly enhanced its singlet oxygen generation with a quantum yield of 0.56 obtained for the (OH)2SiOCPc(Pt)3 conjugate. The (OH)2SiOCPc(Pt)3 conjugate showed highest antimicrobial activity towards Candida albicans and Escherichia coli compared to (OH)2SiOCPc and Pt nanoparticles alone under illumination.

DNA Interaction and DNA Cleavage Studies of a New Platinum(II) Complex Containing Aliphatic and Aromatic Dinitrogen Ligands

A new Pt(II) complex, [Pt(DIP)(LL)](NO₃)₂ (in which DIP is 4,7-diphenyl-1,10-phenanthroline and LL is the aliphatic dinitrogen ligand, N,N-dimethyl-trimethylenediamine), was synthesized and characterized using different physico-chemical methods. The interaction of this complex with calf thymus DNA (CT-DNA) was investigated by absorption, emission, circular dichroism (CD), and viscosity measurements. The complex binds to CT-DNA in an intercalative mode. The calculated binding constant, K_b, was 6.6 × 10⁴ M⁻¹. The enthalpy and entropy changes of the reaction between the complex and CT-DNA showed that the van der Waals interactions and hydrogen bonds are the main forces in the interaction with CT-DNA. In addition, CD study showed that phenanthroline ligand insert between the base pair stack of double helical structure of DNA. It is remarkable that this complex has the ability to cleave the supercoiled plasmid.

Biological evaluation of novel Pt(II) and Pd(II) complexes with pyrazole-containing ligands

The new platinum (II) and palladium (II) complexes (2-4) with ligands 5-(2-hydroxyphenyl)-1,3-dimethyl-4-(dimethoxy)phosphonyl-1H]-pyrazole (1a) and 5-(2-hydroxyphenyl)-1,3-dimethyl-4-methoxycarbonyl-1H]-2-pyrazole (1b) were screened in a search for novel anticancer agents. Thus, alkylating activity, cytotoxicity, ability for induction of apoptosis and binding to DNA were tested. The cis-[Pt(1b)2Cl2] complex (3b) was the most potent alkylating agent in a Preussmann test, in comparison with the other test compounds and cis-platin. The highest cytotoxicity against the HL-60 and NALM-6 leukemia cell lines was observed for complexes 3b and 4b (trans-[Pd(1b)2Cl2]), although the extent of the effect was lower relative to cis-platin. Moreover, both complexes were remarkably less toxic to human umbilical vein endothelial cells (HUVECs) with IC50 values of 3b 14 and 20 times higher than that ones for HL-60 and NALM-6 cells, respectively. Complexes 3b and 4b induced caspase-3 activity. Apoptosis occurred in a strictly dose-dependent manner and required only low concentrations of 4b. However, compounds 3b and 4b showed lower binding affinity to double-stranded DNA than cis-platin.

Uptake of radiolabelled alpha-fetoprotein by experimental mammary adenocarcinoma and adenoma: in vivo and in vitro studies

The biodistribution of iodine-labelled alpha-fetoprotein ( I-AFP) in experimental mammary tumours was studied. C3H mice with subcutaneously transplanted mammary adenocarcinoma and Sprague-Dawley rats treated with -methyl- -nitrosourea for mammary adenoma induction were used as animal models. The accumulation of labelled I-AFP in mouse mammary adenocarcinoma was significantly higher than that in rat mammary adenoma. The tumour/muscle radioactivity ratios increased with time and, 48 h after intravenous injection, were estimated as 23.4 and 6.7, respectively. For experiments, extracts from both mammary tumours were prepared. The extracts were subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), transferred to polyvinylidene difluoride (PVDF) membranes and incubated with I-AFP. A single major AFP-binding protein with a molecular weight of about 30 kDa was detected in both extracts. The amount of AFP-binding protein was clearly higher for adenocarcinoma than for adenoma. In the presence of cross-linking reagent, I-AFP formed a complex (about 100 kDa) with adenocarcinoma proteins.