Synthesis and reactions of platinum(IV) complexes with sodium ascorbate

Reduction of ormaplatin and cis-diamminetetrachloroplatinum(iv) by ascorbic acid and dominant thiols in human plasma: kinetic and mechanistic analyses

The reductions of Pt(iv) anticancer prodrugs [Pt(dach)Cl₄] (ormaplatin/tetraplatin) and cis-[Pt(NH₃)₂Cl₄] by several dominant reductants in human plasma have been characterized and analyzed kinetically and mechanistically.

Bulky N(,N)-(di)alkylethane-1,2-diamineplatinum(II) compounds as precursors for generating unsymmetrically substituted platinum(IV) complexes

Investigations of the influence of bulky groups in the equatorial ligand sphere of platinum(IV) compounds on the complexes' stability and reaction pattern were performed. Four dihydroxidoplatinum(IV) complexes were reacted with anhydrides, cinnamoyl chloride, and n-propyl isocyanate and yielded the symmetric dicarboxylated products or, if steric hindrance was observed, unsymmetrically substituted monocarboxylated analogues. With the aim of raising the steric demand, the following ligands were chosen: N-cyclohexylethane-1,2-diamine, N,N-dimethylethane-1,2-diamine, N,N-diethylethane-1,2-diamine, and N,N-diisopropylethane-1,2-diamine. All of the novel complexes were characterized by electrospray ionization mass spectrometry (ESI-MS), one- and two-dimensional NMR spectroscopy, elemental analysis, and reversed-phase HPLC; complexes B3, C3, C6, and D4 were also analyzed by X-ray diffraction. Additionally, the cytotoxicities of 10 compounds toward the cisplatin-sensitive cell line CH1 and the intrinsically cisplatin-resistant cell lines A549 and SW480 were investigated, and IC50 values down to the nanomolar range were found. To aid in the interpretation of structure-activity relationships, log k(w) values as a measure for the lipophilicity were determined for all of the new complexes, and the rates of reduction of C1, C3, and C4 relative to satraplatin were determined by means of NMR spectroscopy and ESI-MS.

Mono-carboxylated diaminedichloridoplatinum(IV) complexes--selective synthesis, characterization, and cytotoxicity

(OC-6-43)-Dichlorido(N,N-dimethyl-ethane-1,2-diamine)dihydroxidoplatinum(IV) could selectively be mono-carboxylated with succinic anhydride based on the steric hindrance caused by the two methyl groups of the equatorial ligand. Subsequent esterification of the uncoordinated carboxylic acid with alcohols of different lengths (methanol, butanol, hexanol and octanol) afforded the corresponding esters. The synthesized complexes were characterized in detail by elemental analysis, ESI-MS, multinuclear ((1)H, (13)C, (15)N and (195)Pt) NMR spectroscopy and in two cases by X-ray crystallography. Cytotoxicity of novel platinum(IV) compounds was investigated in four human cancer cell lines (CH1, A549, SW480 and SK-OV-3). Remarkably, the most lipophilic complexes showed IC(50) values down to the low micromolar or even nanomolar range.

New organotin(IV) ascorbates: synthesis, spectral characterization, biological and potentiometric studies

New organotin(IV) ascorbates of the general formulae R(3)Sn(HAsc) (where R = Me , n-Pr, n-Bu and Ph) and R(2)Sn(Asc) (where R = n-Bu and Ph) have been synthesized by the reaction of R(n)SnCl(4-n) (where n = 2 or 3) with monosodium-l-ascorbate. The bonding and coordination behaviour in these complexes are discussed on the basis of UV-Vis, IR, Far-IR, (1)H and (13)C NMR, and (119)Sn Mossbauer spectroscopic studies. L-Ascorbic acid acts as a monoanionic bidentate ligand in R(3)Sn(HAsc) coordinating through O(1) and O(3). The Mossbauer studies together with IR and NMR studies suggest that for these polymeric derivatives, the polyhedron is trigonal bipyramidal around tin with three organic groups in the equatorial positions. In R(2)Sn(Asc), L-ascorbic acid acts as dianionic tetradentate ligand and a polymeric structure with octahedral geometry around tin with trans organic groups has been tentatively proposed. The complexes have been assayed for their anti-inflammatory and cardiovascular activity. Ph(2)Sn(Asc) has been found to show the highest activity among the studied complexes. It is suggested on the basis of potentiometric studies of Me(2)Sn(IV) and Me(3)Sn(IV) systems with L-ascorbic acid that under physiological conditions (pH = 7.0) Me(2)Sn(HAsc)(OH) (approximately 60%), Me(2)Sn(OH)(2) (approximately 40%) and Me(3)Sn(HAsc) (approximately 60%), Me(3)Sn(OH) (approximately 40%), respectively, are existing, which may be responsible for their biological activities.