The antitumor activity of di-n-butyltin(IV) glycylglycinate, and the correlation with the structure of dialkyltin(IV) glycylglycinates in solution studied by conductivity measurements and by infrared, nuclear magnetic resonance, and Mössbauer spectroscopic methods

Dibutyltin(IV) and Tributyltin(IV) Derivatives of meso-Tetra(4-sulfonatophenyl)porphine Inhibit the Growth and the Migration of Human Melanoma Cells

Melanoma is the most aggressive and deadly form of skin cancer, which is largely due to its propensity to metastasize. Therefore, with the aim to inhibit the growth and the metastatic dissemination of melanoma cells and to provide a novel treatment option, we studied the effects of the melanoma treatment with two organotin(IV) complexes of the meso-tetra(4-sulfonato-phenyl)porphine, namely (Bu2Sn)2TPPS and (Bu3Sn)4TPPS. In particular, we showed that nanomolar concentrations of (Bu2Sn)2TPPS and (Bu3Sn)4TPPS are sufficient to inhibit melanoma cell growth, to increase the expression of the full-length poly (ADP-ribose) polymerase (PARP-1), to induce the cell cycle arrest respectively at G2/M and G0/G1 through the inhibition of the Cyclin D1 expression and to inhibit cell colony formation. Nanomolar concentrations of (Bu2Sn)2TPPS and (Bu3Sn)4TPPS are also sufficient to inhibit the melanoma cell migration and the expression of some adhesion receptors. Moreover, we report that (Bu2Sn)2TPPS and (Bu3Sn)4TPPS act downstream of BRAF, mainly bypassing its functions, but targeting the STAT3 signalling protein. Finally, these results suggest that (Bu2Sn)2TPPS and (Bu3Sn)4TPPS may be effective therapeutic strategies for their role in the inhibition of melanoma growth and migration.

Diorganotin (IV) complexes with 4-nitro-N-phthaloyl-glycine: Synthesis, characterization, antitumor activity and DNA-binding studies

Two novel diorganotin (IV) complexes, based on 4-nitro-N-phthaloyl-glycine (HL), namely {4-NO2C6H3(CO)2NCH2COO}2Sn(n-Bu)2 (1) and {4-NO2C6H3(CO)2NCH2COO}2SnMe2 (2), were synthesized and characterized by elemental analysis, FT-IR, (1)H- and (13)C-NMR spectroscopic techniques. In vitro antitumor activities of both complexes were evaluated by the 3-(4,5-dimethylthiazoly-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against three human cancer cell lines: HepG-2 (human liver carcinoma), SGC-7901 (human gastric carcinoma) and LS174T (human colon carcinoma). Complex 1 exhibited strong antitumor activity with IC50 values of 1.51±0.41, 1.80±0.63, and 2.48±0.96 μM, respectively; while complex 2 had no obvious effects on the three selected cancer cell lines at high concentrations up to 100 μM. Complex 1-induced apoptosis was further confirmed by morphological observations and annexin V-FITC/PI staining flow cytometry analysis in HepG-2 cells. Cell cycle analysis revealed that complex 1 caused cell cycle arrest at G2/M phase. Molecular mechanism studies suggested that the apoptosis was mediated through the mitochondrial pathway with intracellular reactive oxygen species (ROS) promotion and mitochondrial membrane potential (MMP) disruption by finally activating effector caspase-3/9 to trigger cell apoptosis. Moreover, the interactions of both complexes with calf thymus DNA (CT-DNA) were investigated by using UV-Vis titration and fluorometric competition measurements. The DNA-binding constants Kb (intrinsic binding constant) and K(sv) (quenching constant) had been obtained in the order: 1>2, consisted with the antitumor activity results. Taken together, complex 1 exhibited excellent antitumor activity suggesting that it may be a potential candidate for further chemical optimization and cancer therapy.

New heterobimetallic Cu(II)-Sn2(IV) complex as potential topoisomerase I inhibitor: in vitro DNA binding, cleavage and cytotoxicity against human cancer cell lines

The new heterobimetallic Cu(II)-Sn(2)(IV)/Ni(II)-Sn(2)(IV) complexes 1 and 2 bearing bioactive pharmacophore ligand scaffold; 1,10-phenanthroline and ethylenediamine were synthesized and characterized by spectroscopic (IR, UV-vis, NMR, ESI-MS) and analytical methods. The in vitro DNA binding studies of 1 and 2 with CT-DNA were carried out by employing various biophysical methods which reveal strong electrostatic binding via phosphate backbone of DNA helix, in addition to partial intercalation in the minor groove and stabilized by intramolecular hydrogen bonding. To gain further insight into the molecular recognition at the target site, UV-vis titrations of 1 with 5'-GMP was carried out and validated by (1)H and (31)P NMR. Complex 1 cleaved pBR322 DNA via oxidative pathway and exhibited high inhibition activity against Topo-I at 20 μM. Furthermore, the cytotoxicity of 1 was examined on a panel of human tumor cell lines of different histological origins showing promising antitumor activity.

Organotin(IV) complexes of carboxylic acid derivatives

A comprehensive review, >100 references, on organotin(IV) complexes of the carboxylic acid derivatives are presented with special reference to their methods of synthesis, spectroscopic and structural studies and their biological activities. The structures of these complexes are discussed on the basis of IR, multinuclear (1H-, 13C- and 119Sn-) NMR.

Design and synthesis of heterobimetallic topoisomerase I and II inhibitor complexes: in vitro DNA binding, interaction with 5'-GMP and 5'-TMP and cleavage studies

New potential cancer chemotherapeutic complexes Cu-Sn(2)/Zn-Sn(2) 3 and 4 were designed and prepared as topoisomerases inhibitors; their in vitro DNA binding studies were carried out which reveal strong electrostatic binding via phosphate backbone of DNA helix, in addition to other binding modes viz. coordinate covalent and partial intercalation. To throw insight to molecular binding event at the target site, UV-vis titrations of 3 and 4 with mononucleotides of interest, viz, 5'-GMP and 5'-TMP were carried out, (in case of 4) by (1)H and (31)P NMR. Cleavage studies employing gel electrophoresis demonstrate both the complexes 3 and 4 are efficient cleavage agents and are specific groove binders (complex 3 binds to both major and minor groove while complex 4 is specifically minor groove binder only). In addition, the complexes show high inhibition activity against topoisomerase I and II. However, complex 4 exhibits significant inhibitory effects on the Topo I activity at a very low concentration approximately 2.5 microM.

Synthesis, characterization and in vitro cytotoxicity of new organotin(IV) derivatives of N-methylglycine

The synthesis and characterization of new coordination compounds of some diorganotins(IV) with N-methylglycine (sarcosine) are reported; all these derivatives mainly tend to assume a chelate structure. As single crystals were not obtained, a large number of experimental techniques were used to accomplish a definitive characterization and determination of their structure. Results obtained by (1)H/(119)Sn NMR, FT-IR and (119)mSn-Mössbauer spectroscopy and thermogravimetric analysis allow us to deduce the pentacoordination for 1:1 (Sn/sarcosine) derivatives [R(2)SnCl(2)(Sar)](+)Cl(-) (R=Me, n-Bu) in a trigonal-bipyramidal structure, and the hexacoordination for 1:2 complexes [R'(2)Sn(Sar)(2)](2+)2Cl(-) (R'=Me, n-Bu, Ph) in an octahedral structure; however, the probability of partially or totally non-chelate structures for some adducts increases with the steric hindrance of the R/R' groups and the number of the sarcosine molecules bound to the tin atom, so that they give rise to fluxional equilibria in solution. Finally, the synthesized compounds have been tested for in vitro cytotoxic activity against human adenocarcinoma HeLa cells showing, in some cases, strong activity even at low concentration.

The synthesis, and molecular and crystal structure of diphenyl(2-oxidonaphthylmethyl-iminoacetato)tin(IV)

The new diorganotin complex ((C6H5)2Sn(OC10H6CH=NCH2COO)) was prepared and characterized by 1H NMR, IR, elemental analysis, and a single crystal X-ray diffraction study. The crystals are monoclinic, space group P21/a with a = 16.9167(9) Å, b = 19.1276(16) Å, c = 26.538(2) Å, β = 100.534(6)°, V = 8442.5(11) Å3, Z = 16, and Dcalc = 1.574 Mg m−3. The final discrepancy factors are RF = 0.030, and RW = 0.021 for 6524 significant reflections. The tin atom has a distorted trigonal bipyramidal coordination, with no short intermolecular contacts. The two axial Sn—O bonds of 2.12 Å and 2.09 Å and the equatorial Sn—N bond of 2.14 Å are among the shortest found in related complexes. Key words: diorganotin(IV), bicycloazastannoxide, trigonal bipyramidal, antitumour.

The antitumor activity and the structure of bis(adeninato-N9) diphenyltin(IV)

Bis(adeninato-N9)diphenyltin(IV) has been selected as a tumor panel compound by the U.S. National Cancer Institute and tested against a number of tumors according to standard protocols. The activity criteria were not passed. The solid state structure of the environment of tin in the complex has been definitely established to be of the tetrahedral type by means of 119Sn Mössbauer-Zeeman spectroscopy; this configuration has been assumed to be maintained also in aqueous suspensions of the drug, in conditions corresponding to the administration to mice. The occurrence of strong Sn-N bonds, consistently resistant to hydrolytic processes, has been assumed, and correlated to the observed low toxicity of the drug. The extent of the antitumor action corresponds to the standard response to Ph2SnIV moieties.