Antitumor complexes of platinum with carrier molecules. 3. Cytotoxicity of some platinum amino acid complexes against cisplatin-sensitive and resistant L1210 leukemia cells

Platinum-Based Antitumor Drugs Containing Enantiomerically Pure α-Trifluoromethyl Alanine as Ligand

Synthetic amino acids such as fluorinated alpha-amino acids are currently actively investigated for their biological activity. Herein, we report on the synthesis and characterization of platinum complexes containing an N,O-chelated pure enantiomer of alpha-trifluoromethylalanine (alpha-Tfm-Ala). The compounds are either anionic, K[PtCl2(alpha-Tfm-Ala)], or cationic, [PtAm2(alpha-Tfm-Ala)](NO3) (Am2= (NH3)2, ethylendiamine (en), 1,10-phenanthroline (phen), and 2,9-dimethyl-1,10-phenanthroline (Me2phen)). All complexes are highly soluble in water and have been fully characterized by NMR spectroscopy. In vitro cytotoxicity assays on different human tumor cell lines have been performed on some of the isolated compounds. [Pt(NH3)2(alpha-Tfm-Ala)] with R configuration of the amino acid proved to have an activity comparable to that of the reference compound cisplatin. Flow cytometric analysis on NCI-H460 tumor cells (absence of G2/M arrest, which instead is observed in the case of cisplatin) suggests a mechanism of action different from that of cisplatin.

Ab initio and density functional theory studies on vibrational spectra of palladium (II) and platinum (II) complexes of methionine and histidine: effect of theoretical methods and basis sets

The vibrational spectra of methionine and histidine-containing palladium (II) and platinum (II) complexes, cis-M(Met)X2 and cis-M(His)X2 (M = Pd and Pt; X = F, Cl, Br and I; Met = methionine, His = histidine), have been systematically investigated by ab initio Restricted Hartree-Fock (RHF) and density functional B3LYP methods with LanL2DZ and SDD basis sets. The geometries of cis-Pd(Met)Cl2, cis-Pt(Met)Cl2, cis-Pd(His)Cl2 and cis-Pt(His)I2 optimized and vibrational frequencies and IR intensities of cis-M(Met)Cl2 and cis-M(His)Cl2 (M = Pd and Pt) calculated are evaluated via comparison with the experimental values. The vibrational frequencies calculated show that the methods, rather than basis sets, affect the accuracy of the calculation. The best results that can reproduce the experimental ones are obtained at B3LYP level without any scale factor used. The vibrational frequencies of cis-M(Met)X2 and cis-M(His)X2 (M = Pd and Pt; X = F, Br and I) that have not yet been experimentally reported are predicted.

Synthesis, cytotoxic activity on MCF-7 cell line and mutagenic activity of platinum(II) complexes with 2-substituted benzimidazole ligands

Four Pt(II) complexes with 2-H/or-methyl/or-aminomethylbenzimidazole or 1,2-dimethylbenzimidazole ligands as "non-leaving groups" were synthesized and their antiproliferative properties were tested against the human MCF-7 breast cancer cell line. The mutagenic potentials of the complexes were tested in Salmonella typhimurium strains TA 98 and TA 100 in the absence of S9 rat liver fraction. In general, Pt(II) complexes tested which were found to be less active than cisplatin, exhibited moderate in vitro cytotoxic activity on MCF-7 cell line. Among the complexes tested, Pt(II) complex with 2-aminomethylbenzimidazole ligand was found to be highly mutagenic in S. typhimurium TA 98 and low mutagenic in S. typhimurium TA 100. Pt(II) complex with 1,2-dimethylbenzimidazole was mutagenic only in S. typhimurium TA 98. The other two complexes were found to be non-mutagen in both strains.

Synthesis and in vitro cytotoxicity of lipophilic platinum(II) complexes

A number of lipophilic platinum(II) complexes of the general structures cis-[Pt(LA)2Cl2] and [Pt(LD)Cl2] were synthesised. Long chain amines (LA) and diamines (LD), prepared from lipidic amino acids, were used as ligands. The in vitro cytotoxicity of the complexes was evaluated against four cell lines (P388, NSCLC-N6, E39, M96). cis-Dichloro-bis(2-aminohexadecanol)platinum(II) was the most active against P388, NSCLC-N6 and E39 (IC50: 11 micrograms/ml, 25 micrograms/ml, 31 micrograms/ml), while dichloro(1,3-heptadecanediamine)platinum(II) presented the highest activity against M96 (IC50: 13 micrograms/ml).

DNA binding studies with cis-dichlorobis (5(6)-non/chlorosubstituted-2-hydroxymethyl-benzimidazole) platinum(II) complexes

The DNA binding properties of two new platinum compounds, cis-[Pt(L)2Cl2]. 2H2O where L is 5(6)-non/chlorosubstituted-2-hydroxymethylbenzimidazole, were examined and compared with cisplatin. The platinum compounds (compounds I and II) were used to modify DNA, which was then used in electrophoretic mobility shift assays with the high mobility group (HMG)-do-main protein, HMG1. The DNA platinated with these compounds was specifically recognized by HMG1. It was concluded that the adducts formed by compounds I and II distort the DNA in a manner similar to cisplatin diadducts.

Aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine]sulfatoplatinum(II) complexes with variable substituents in the 2-phenyl ring, II: Correlation of molecular structure and estrogenic activity of breast and prostate cancer inhibiting. [erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-halo-4- hydroxyphenyl)ethylenediamine]platinum(II) complexes

Complete three-dimensional X-ray crystal structure analyses of estrogenic [erythro-1-(2,6-dichloro-4-hydroxyphenyl)-2-(2-halo-4- hydroxyphenyl)ethylenediamine]diiodoplatinum(II) complexes (halo = fluoro:erythro-8PtI2 and halo = chloro:erythro-9-PtI2) which were synthesized for application in breast and prostate cancer, have been carried out. 6239 as well as 6521 reflexes were measured and refined to an R-value of 0.105 and 0.066, respectively. The molecules of erythro-8-PtI2 are displaced laterally from a possible Pt-Pt-axis separated, alternatingly, by Pt-Pt-distances of 3.62 A and 6.27 A. A comparable structure possesses erythro-9-PtI2 with Pt-Pt-distances of 3.59 A and 6.32 A. The ethylenediamine ligands of erythro-8-PtI2 and erythro-9-PtI2 are puckered and exist in half chair conformations. For both complexes the 2,6-dichloro-4-hydroxyphenyl ring is equatorially arranged, while the 2-halo-4-hydroxyphenyl ring is nearly perpendicular to the N-Pt-N plane. The O-O-distance between the phenolic oxygens amounts to 8.1 A in erythro-8-PtI2 and to 7.8 A in erythro-9-PtI2. Though these O-O-distances differ strongly from that (12.1 A), which is considered to be necessary for the binding of an estrogen to its receptor, [1-(2,6-dichloro-4-hydroxyphenyl)- 2-(2-halo-4-hydroxyphenyl)ethylenediamine)]platinum(II) complexes show estrogenic effects which are, however, strongly reduced compared to that of therapeutically used estrogens like diethylstilbestrol. The relationship between molecular structure and estrogenicity as well as the significance of the latter for antitumor activity and untoward side effects are thoroughly discussed.