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Palladium-catalyzed homogeneous coupling reactions of steroids with organostannanes.

Direct and carbonylative coupling reactions of various steroid derivatives possessing iodo- and bromo-alkenyl moiety (17-iodo-androst-16-ene, 1, 17-bromoandrost-2,16-diene, 2, 17-iodo-4-aza-4-methylandrost-16-en-3-one, 3, 17-iodo-4-azaandrost-16-en-3-one, 4) with vinyltributylstannane and ethynyltributylstannane were carried out in the presence of various palladium catalysts. While carbonylation took place only with vinyltributylstannane, 17-vinyl-, and 17-ethynyl-delta 16 steroids were produced via direct coupling with vinyltributylstannane and ethynyltributylstannane, respectively. Activities of some catalysts based on Pd(0) and Pd(II) precursors were compared, and Pd(PPh3)4 was found to be superior to other complexes in most cases. In the coupling of 17-iodoandrost-16-ene with organostannanes Pd2(dba)3 + 8 AsPh3 in situ catalyst was found to be even more effective.

Androstenes↗

Immunological consequences of dioctyltin dichloride (DOTC)-induced thymic injury.

Inbred rats fed diets containing 75 ppm dioctyltin dichloride (DOTC) for 8 or 12 weeks demonstrated marked reduction in thymic weight. This reduction was accompanied by a decrease in the number of W3/25 positive phenotypic circulating lymphocytes and an impaired ability to respond to suboptimal mitogenic stimulation. Responsiveness to alloantigenic stimulation, as measured by mixed leucocyte reactions, was depressed in DOTC-fed animals whereas no effect on natural cytotoxicity in nonimmunized treated or control rats was evident. No difference was found in the ability of treated compared to untreated animals to mount specific antibody responses against sheep red blood cells, and no evidence was found to indicate toxicity to lymphocytes in vivo. The investigation showed that DOTC administration resulted in a selective immunodeficiency.

Administration, Oral↗

Environmental methylation of tin: an assessment.

The chemical and biological methylation of tin under environmental conditions is reviewed. The question of whether methyltin species form in situ in the environment is also considered. Analytical approaches using hydridization techniques give quite sensitive results. Incubation studies of environmental microorganisms and sediment have demonstrated the formation of methyltin species, and similar conversions have been observed with chemical methylating agents such as methyl cobalamin and methyl iodide.

Environmental Pollution↗

The accumulation of organotins in adult and seed oysters from selected estuaries prior to the introduction of U.K. regulations governing the use of tributyltin-based antifouling paints.

Between April and November, 1985, a study of the levels of organotins in adult and seed Crassostrea gigas grown in the southwest and southeast of England was carried out. This work corresponds with a similar study of organotin water levels (reported separately). The analytical procedure used was directly coupled high performance liquid chromatography-flame atomic absorption spectrometry. Individual adult oysters and groups of 20-40 seed oysters were taken for analysis on a monthly basis. The profiles of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) are discussed in relation to each other and levels found in the waters. In general, levels of all three organotin species were found to be higher in the seed oysters. Mean levels of TBT reached 3.1 micrograms g-1 in seed oysters from the Exe, Devon, in October, whereas mean levels of DBT and MBT reached 16.1 and 16.7 micrograms g-1 in Teign, Devon, seed oysters in October. Bioconcentration factors of approximately 1000 were found, but seem to be greater when lower levels of TBT were present in the water, perhaps indicating a more 'efficient' removal from the water. The degree of shell thickening was calculated for all oysters submitted for analysis. The highest percentage of adult oysters with severely thickened shells was found at Tollesbury Fleet, where 61% of oysters showed shell thickness index values of six or less. Generally, two peaks in TBT levels in the oysters were observed, in the late spring and early summer: these seem to correlate with peak levels of TBT in the waters immediately preceding these times. A large proportion of the DBT and MBT found in the oysters seems to come from the metabolism of the TBT ingested. It is suggested that high sediment loadings may contribute to the severe deformation of oysters grown at Tollesbury Fleet, but only in the presence of TBT.

Aging↗

Occurrence of butyltin species in sewage and sludge in Canada.

Samples of sewage treatment influent, effluent and sludges collected monthly from five Canadian cities over the period from July 1990 to January 1991 were analysed for butyltin and octyltin species. Monobutyltin was found in all influent samples, but dibutyltin and tributyltin were found only infrequently, and octyltin species were not found at all. In the case of monobutyltin, there was significant reduction in its concentration by degradation and adsorption to sludge during passage through the sewage treatment plant. The average reduction was 40%. The monobutyltin found in the effluent likely came from its use as a poly (vinyl chloride) stabilizer, and from the degradation of tributyltin, which is used as a slimicide. No butyltin or octyltin species was found in five landfill leachate samples in southern Ontario during the same period.

Canada↗

Thymic involution in rats given diets containing dioctyltin dichloride.

Inbred rats fed diets containing 150 ppm dioctyltin dichloride (DOTC) demonstrated a progressive reduction in thymic weight. This was accompanied by a decrease in both the number of circulating lymphocytes and their ability to respond to mitogenic stimulation. Morphologically the thymuses from treated animals showed a loss of cortical thymocytes and a marked vacuolation of the reticular epithelial cells (REC). After return to normal diet for 4 weeks vacuolated REC were still present and PHA-induced lymphocyte blastogenesis remained low. Adrenalectomy failed to alter the atrophic action of DOTC on the thymus and although administration of hydrocortisone alone produced thymic atrophy, no damage to the REC was observed. The results show that thymic atrophy resulting from DOTC administration differs from that induced by steroids and lends support for the hypothesis that DOTC acts selectively on the thymus in such a way that the humoral function of the organ may be affected.

Adrenalectomy↗

Analysis of organotin uptake in Escherichia coli K-12.

The effect of tributyltin chloride (TBT) was potentiated by the presence of Tris ions in the growth medium compared with phosphate ions. The growth of Escherichia coli in the presence of Tris ions was inhibited completely at a concentration of 25 microM TBT whereas 79% growth was recorded in the presence of phosphate ions. Tris ions caused more protein to be released into the medium than phosphate ions. However, apart from protein release the rate of organotin uptake was less in Tris than in phosphate ions. Phosphate ions may play a positive role in the active accumulation of organotin into E. coli cells by providing cellular energy.

Bacterial Proteins↗

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.

The in vivo activity of Bu2nSnGlyGly, Na(Cl2GaGlyGly), and ClGaGlyGly (GlyGly2- = glycylglycinate) has been investigated in connection with a number of tumors. Positive results have been obtained only for the Bu2nSnIV complex in the case of leukemia P-388. In order to try to interpret the pharmacological data on a molecular basis, the nature of the species present in solutions of AlK2Sn GlyGly complexes, as well as the reactivity of aqueous Me2SnGlyGly, have been studied. The presence of chelated species (I), Figure 1, in organic solvents, and the equilibrium (I) in equilibrium (II), Figure 1, in water and mixed water-organic solvent systems, have been inferred from conductance measurements, as well as from studies by Mössbauer (in frozen solution), 1H, 13C, and 119Sn NMR, and ir spectroscopy. Moreover, solvated (II) would release AlK2SnIV moieties, as evidenced by the slow formation of (Me2SnO)n from aqueous Me2Sn GlyGly. The involvement of (I) and (II) in the transportation of these drugs across cell membranes is discussed.

Animals↗

Diorganotin dihalide complexes of 2,2'-biimidazole. A preliminary study of their inhibitory effects on cell division.

We report the synthesis of new complexes with the general formula (R2SnX2)y.H2BiIm, where y = 1 or 2; R = Me, Et, Bun; X = Cl or Br (for R = Et) and H2BiIm = 2,2'-Biimidazole. The complexes have been characterized by elemental analysis and Mössbauer, infra-red and 1H n.m.r. spectroscopy and tested (like the ligand, Me2SnCl2 and Et2SnCl2) against P388D1 leukemic cells.

Animals↗

The interaction of native DNA with dimethyltin(IV) species.

The reaction of aqueous native DNA (calf thymus) with the solvated organotin(IV) species [(CH3)2SnCl2(C2H5OH)n], as well as with [(CH3)2Sn(OH)(H2O)n]+ and (CH3)2Sn(OH)2 (i.e., the hydrolysis products of aqueous (CH3)2SnCl2 at pH approximately 5 and pH approximately 7.4 respectively), was investigated by 119Sn Mössbauer spectroscopy. The addition of [(CH3)2SnCl2(C2H5OH)n] to DNA yielded a solid product, possibly (CH3)2Sn(DNA phosphodiester)2, where the environment of the tin atom is trans-octahedral with linear CSnC skeleton, and the equatorial atoms may consist of oxygen or nitrogen from water as well as from the nucleic acid constituents. No interaction with DNA apparently takes place due to hydrolyzed dimethyltin(IV) species, which occur in aqueous phases at approximate physiological pH values. The reaction pathway is then assumed to require weakly solvated, easily dissociable species such as [(CH3)2SnCl2(C2H5OH)n], which would imply in vivo reactivity of cellular DNA with organotins from hydrophobic sites.

DNA↗

Synthesis, structure, and spectroscopic properties of acetato(dimethyl)(pyridine-2-carbaldehydethiosemicarbazonato)tin(IV) acetic acid solvate, [SnMe2(PyTSC)(OAc)].HOAc. Comparison of its biological activity with that of some structurally related diorganotin(IV) bis(thiosemicarbazonates).

The synthesis, X-ray structure, behavior in solution, and biological properties of the complex [SnMe2(PyTSC)(OAc)].HOAc (HPyTSC = pyridine-2-carbaldehydethiosemicarbazone) are reported. The tin atom of this complex is coordinated to an N,N,S-tridentate PyTSC- anion, to a monodentate acetate ion, and to the two methyl groups in an approximately pentagonal bipyramidal environment with a vacant equatorial position. The complex partially evolves in DMSO and in DMSO/CHxCl4-x (X = 1, 2) mixtures, giving HPyTSC and SnMe2(OAc)2. [SnMe2 (PyTSC)(OAc)].HOAc, [SnMe2(DAPTSC)], and [SnPh2(DAPTSC)].2DMF (H2DAPTSC = 2,6-diacetylpyridine bis(thiosemicarbazone)) all suppress proliferation of Friend erythroleukaemia cells (FLC). DMSO-induced differentiation of FLC is slightly suppressed by [SnMe2(DAPTSC)] and is unaffected by [SnPh2(DAPTSC)].2DMF and [SnMe2(PyTSC)(OAc)].HOAc.

Animals↗

Diorganotin(IV) antitumor agent. (C2H5)2SnCl2 (phen)/nucleotides aqueous and solid-state coordination chemistry and its DNA binding studies.

This contribution reports a solution and solid-state study of the aqueous nucleotide coordination chemistry of the diethyltin(IV) antitumor agent, (C2H5)2SnCl2(phen). [trans-en2Os(eta-H2)] (CF3SO3)2, a versatile 1H NMR probe for biomolecules, is first used to investigate the interaction of (C2H5)2SnCl2(phen) with DGMP in neutral aqueous solution, and then the synthesis of mixed-ligands complexes formulated as (C2H5)2SnCl(phen)(Nu) (Nu is nucleotide) by reactions of (C2H5)2SnCl2(phen) with equimolar nucleotides under biologically relevant conditions is described. The new complexes were characterized by 500 MHz 1H, 31P NMR spectra; these spectroscopic data suggest that one of cis-chloro atoms in (C2H5)2SnCl2(phen) is substituted by nucleotide, and that Sn(IV) is directly coordinated to the phosphate group of the nucleotide. No evidence was found for the coordination via donor atoms of the base. On the basis of the above model studies, absorbance, fluorescence and cyclic voltammetric methods, viscosity determination, as well as agrose gel electrophoresis of superhelical pBR322 plasmid DNA were used to study the interaction of (C2H5)2SnCl2(phen) with DNA. The results indicate that (C2H5)2SnCl2(phen) binds to DNA by double modes. The drug first reacts electrostatically with the sugar-phosphate backbone of DNA; this results in changes of DNA conformation, and then phen ligand can intercalate into double-helix DNA and cause unwinding of the DNA.

Antineoplastic Agents↗

Increasing effect of tri-n-butyltins and triphenyltins on the frequency of chemically induced chromosome aberrations in cultured Chinese hamster cells.

Organotins have been widely used as anti-fouling coatings for fishing nets and ship bottoms, and marine pollution by them has become a serious environmental problem. In this communication, the potentiating effects of three kinds of tri-n-butyltins and three thiphenyltins on chromosome aberrations were studied in Chinese hamster CHO K1 cells. None of the organotins studied showed any clastogenic activity under the experimental conditions without rat liver S9. Post-treatment with organotins, however, increased the number of breakage-type (but not exchange-type) chromatid aberrations induced by five kinds of S-phase-dependent clastogens: MMC, cisPt, 4NQO, MMS, and AMD). Enhancement of the induction of chromosome aberrations by MMC was observed when cells were treated with organotins during the G2 phase. These results suggest that organotin G2 effect causes potentiating effects. Organotins also enhanced the induction of breakage-type chromatid aberrations by clastogenic pollutants in chlorinated tap water, indicating their potential for a more realistic health risk.

Animals↗