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PubMed2001

Potentiometric and spectroscopic studies on the dimethyltin(IV) complexes of 2-hydroxyhippuric acid.

Equilibrium and spectroscopic (1H, 13C NMR and 119Sn Mössbauer) studies in aqueous solution are reported for dimethyltin(IV) complexes of 2-hydroxyhippuric acid (Sal-Gly). Below pH 4, oxygen-coordinated complexes MLH and ML are formed. In the pH range 5-8.5, the species MLH(-1), predominates at any metal-to-ligand ratio. The ligand exchange of this species is slow on the NMR time scale, which allows its structural characterization by NMR spectroscopy: the coordination polyhedron around the tin atom is distorted trigonal bipyramidal, with tridentate [O-,N-,COO-] coordination of Sal-Gly, involving two equatorial methyl groups. The NMR results reveal that the main cause of the distortion of the polyhedron is the large CH3-Sn-CH3 angle of 136+/-4 degrees. The presented results supplement the data available on the dimethyltin(IV)-promoted amide deprotonation of peptides, and provide further arguments for the fundamental role of the carboxylate as an anchoring group in this process.

Electrochemistry↗

PubMed2002

Equilibrium and structural studies on metal complexes of carbohyrates and their derivatives.

A summary is presented of the studies of our group on metal complexes of carbohydrates (aldoses, ketoses, mono-, di- and polysaccharides) and their derivatives (aldonic, alduronic acids, polyalcohols, amino sugars, amino acid sugar adducts, AMP, ATP, etc.). The results are reported of equilibrium, electrochemical, solution and solid-state structural studies of complexes of transition metals [Cu(II), Fe(III), Ni(II), Zn(II), Co(II), Ag(I), Mn in different oxidation states and organotin(IV)]. The structural parameters (coordination number, bond distance, and Debye-Waller factor) obtained by extended X-ray absorption fine structure spectroscopic (EXAFS) spectroscopy are discussed in detail. The general rules concerning the formation and structure of such complexes are emphasized.

Carbohydrate Conformation↗

PubMed1989

Acute pancreatitis and bile duct lesions in rat induced by dibutyltin dichloride.

After i.v. or i.p. administration of a single dose of dibutyltin dichloride (DBTC) the following changes were observed in pancreas and bile ducts of male rats: acute interstitial pancreatitis, enlargement of diameter and destruction of epithelial cells of the bile ducts, increase of serum alkaline phosphatase activity. The effects were dependent on the dose of DBTC (1, 4 or 6 mg/kg body weight), the route of administration and the time after treatment. The pancreatitis induced by DBTC is under further investigation as a model of experimental pancreatitis.

Acute Disease↗

PubMed2002

Imposex and tributyltin contamination as a consequence of the establishment of a marina, and increasing yachting activities at Phuket Island, Thailand.

The objective was to investigate how tributyltin (TBT) contamination resulting from the establishment of a new marina and increasing yachting activities at Phuket Island, Thailand affects the area. A minimum of 30 specimen of the mangrove dwelling muricid Chicoreus capucinus were collected at five stations 2 months before and 5, 9, 18 and 33 months after Yacht Haven Marina was constructed. Imposex measured as RPLI and VDSI were significantly correlated to duration of time after construction and distance from the marina. All females developed imposex close to the marina after 18 months, whereas no significant increase occurred at stations more than 2 km from the marina. To evaluate the range of effects of the increasing yachting activities the muricid Thais distinguenda was used as an indicator of imposex at two popular mooring sites for yachts at Phi Phi and Raja Island in Phangna Bay, Thailand. The incidence of imposex was 100% at stations close to the mooring sites. A significant correlation existed between the distance from the sites and the incidence of imposex. The increasing incidence of imposex suggest that TBT contamination is worsening, against global trends, because regulations prohibiting the use of TBT-based paints, do not exist in Thailand.

Animals↗

PubMed2002

Antifoulant (butyltin and copper) concentrations in sediments from the Great Barrier Reef World Heritage Area, Australia.

Antifoulant concentrations were determined in marine sediments collected from commercial harbours, marinas, mooring locations on mid-shelf continental islands, and outer reef sites in four regions within the Great Barrier Reef World Heritage Area in 1999. Highest copper concentrations were present in sediments collected from commercial harbour sampling sites (28-233 microg Cu g(-1) dry wt.). In contrast, copper concentrations in sediments collected from boat mooring sites on mid-shelf continental islands and outer reef sites were at background concentrations (i.e. <20 pg Cu g(-1) dry wt.). Butyltin was only detectable in four of the 42 sediments sampled for analysis, and was only present in sediments collected from commercial harbours (18-1275 ng Sn g(-1) dry wt.) and from marinas (4-5 ng Sn g(-1) dry wt.). The detection of tributyltin at marina sites implies that this antifoulant may continue to be used illegally on the hulls of smaller recreational vessels. Sediment samples were also collected opportunistically from the site of a 22,000 t cargo ship grounding in May 1999 at Heath Reef, in the far northern Great Barrier Reef. Butyltin concentrations were grossly elevated (660-340,000 ng Sn g(-1) dry wt.) at the grounding site. The impact of residual antifoulants at large ship grounding sites should be recognised as a significant, long-term environmental problem unless antfoulant clean-up strategies are undertaken.

Australia↗

PubMed2003

Assessment of adsorption behavior of dibutyltin (DBT) to clay-rich sediments in comparison to the highly toxic tributyltin (TBT).

The sorption behavior of dibutyltin (DBT) to four types of natural clay-rich sediments as a function of pH and salinity was studied. The strongest affinity of DBT was found to the montmorillonite-rich sediment, which is characterized by the highest specific surface area and cation exchange capacity of the four used sediments. Kd values range between 12 and 40 (l/kg) on simulated marine conditions (pH 8, salinity 32%). A maximum of DBT adsorption was found at a salinity of 0% and pH 6. Desorption occurred over the entire studied pH range (4-8) when contaminated sediments interact with butyltin-free water. The maximum of desorption coincided with the minimum of adsorption, and vice versa. The results of DBT adsorption are compared with tributyltin (TBT), and the mechanism of the adsorption process is discussed.

Adsorption↗

PubMed2000

Promotion of morphological transformation by Di-n-butyltin dichloride in C3H/10T1/2 cells: prediction by prior expression of tumour promoter-responsive genes.

Previous studies in our laboratory have shown that chemical treatments may induce increases in proliferin gene family mRNA accumulation in cultured murine embryonic cells. Proliferin inductions are highly correlated with subsequent promotional outcomes during two-stage focus-formation assays in C3H/10T1/2 cell cultures. In work reported here, the strong affiliation between these two responses was further validated after treating cells with di-n-butyltin dichloride which is a polyvinyl chloride (PVC) plastic additive that often contaminates food and water. Increased proliferin expression and promotion of morphological transformation occurred at similar concentrations. Promotion of transformation was detected at di-n-butyltin dichloride concentrations of 80 nM (24 ng/ml) and above, if added to initiated cultures before confluent monolayers had formed. Proliferin induction and morphological transformation were both reduced in confluent cultures treated with di-n-butyltin dichloride, as compared to subconfluent cultures. Proliferin expression measured in near-confluent cultures was induced up to 10-fold during the 36-hr period following di-n-butyltin dichloride exposure and was accompanied by increased accumulation of transcripts from many genes regulated by oxidative stresses, growth-inducing agents, and/or other promoting agents (asbestos, superoxide radicals ). Di-n-butyltin dichloride-induced mRNA species included members of the fos and jun proto-oncogene families, c-myc, egr1, ribonucleotide reductase (R2 subunit), odc, macrophage chemotactic protein/je, hsp70, metallothionine IIA, c-sod and mn-sod. The observed patterns of RNA accumulation suggested that a small subset of mRNA species, including proliferin, exhibit regulatory behaviour as a response to dissimilar agents or conditions that promote focus-formation in C3H/10T1/2 cultures. Plausible predictions of promotional effects in two-stage morphological transformation assays can be made from gene-expression responses to test agents.

Animals↗

PubMed2001

Effects of maternal age on teratogenicity of di-n-butyltin diacetate in rats.

The present study was designed to assess changes in the teratogenic potency of di-n-butyltin diacetate (DBTA) with increasing maternal age in rats. Pregnant Wistar rats of 3, 7.5 or 12 months were treated orally with DBTA at 0, 7.5, 10, 15 or 22 mg/kg on day 8 of gestation. Cesarean sections were performed on day 20 of gestation. Maternal age had greater impact on litter size in the 7.5- and 12-month dams than the 3-month dams. The death of most of the fetuses of the 12-month dams made it difficult to evaluate the teratogenic potency of DBTA. In 3-month groups, fetuses with external malformation, such as cleft mandible, cleft lower lip, ankyloglossia and/or schistoglossia, which are malformations typical of DBTA, were observed at 15 and 22 mg/kg, while similar malformations were observed in 7.5-month groups at doses of 10 mg/kg and above. At 15 and 22 mg/kg, the incidences of these malformations in 7.5-month groups were similar to these from 3-month groups. In our previous studies, however, single DBTA-treatment at 10 mg/kg on day 8 of gestation has not produced such malformations from 3-month dams. The results suggest that the teratogenic potency of DBTA in 7.5-month dams may be greater than in 3-month dams.

Abnormalities, Drug-Induced↗

PubMed1999

Effects of pretreatment with cytochrome P-450 inducers, especially phenobarbital on triphenyltin metabolism and toxicity in hamsters.

The effects of cytochrome P-450 (CYP) induction by phenobarbital (PB), CYP 2B, 2C, and 3A inducer in mammalians, on triphenyltin metabolism and toxicity in hamsters were studied. A single dose of 50 mg/kg of triphenyltin chloride was given by gavage to hamsters after pretreatment with or without PB for 3 days continuously at a daily dose of 80 mg/kg intraperitoneally (i.p.). Although the triphenyltin produced marked but reversible hyperglycemia and hypertriglyceridemia in PB-untreated hamsters, the pretreatment of hamsters with PB, which increased levels of CYP, suppressed the diabetogenic effects compared with PB-untreated hamsters. Furthermore, we investigated whether the mitigation of triphenyltin-induced diabetogenic toxicity by PB pretreatment is due to an alteration of triphenyltin metabolism. Triphenyltin and its metabolites in liver, kidneys, pancreas and brain were determined by gas chromatography periodically for 96 h after triphenyltin administration in both groups of hamsters. The initial triphenyltin levels in the tissues of PB-pretreated hamsters were about half of those in the tissues of PB-untreated hamsters and PB pretreatment accelerated metabolism of triphenyltin at early stage in hamsters. We also examined the other CYP 1A and 2A inducers, beta-naphthoflavone (B-NF) and 3-methylcholanthrene (MC). The PB pretreatment showed the strongest suppression of the toxicity at 24 h after the triphenyltin intubation, compared with the effects of B-NF and MC. In addition, the maximum proportion of diphenyltin to parent triphenyltin in pancreas was observed in PB-treated hamsters. These findings suggest that the induction of CYP system enzymes affects the metabolism and toxicity of triphenyltin in hamsters. Especially, based on effects of PB and other CYP inducers, PB induction has a key role in suppressing the diabetogenic action of triphenyltin, i.e. by decreasing triphenyltin accumulation in the hamsters.

Animals↗

PubMed2000

Tri-n-butyltin-induced change in cellular level of glutathione in rat thymocytes: a flow cytometric study.

Since some of organotins, accumulated in edible mollusks of aquatic environments, exert a variety of toxic actions on experimental animals, it causes concern for the health of humans. We examined the effects of tri-n-butyltin chloride (TBT) and other organotins (triethyltin chloride, trimethyltin chloride, triphenyltin chloride and tetrabutyltin) on cellular content of glutathione (GSH) in rat thymocytes using a flow cytometer to further characterize the toxicity of TBT. When the cells were incubated with TBT at concentrations of 3 nM or more for 15 min, the cellular content of GSH dose-dependently decreased. However, it completely or partly recovered until 180 min even in the continued presence of TBT. This recovery was temperature-sensitive, suggesting an involvement of metabolic process. The efficacy of TBT to decrease the cellular content of GSH was greater than those of other organotins. Results suggest that TBT and some organotins at environmentally relevant (nanomolar) concentrations significantly reduce the cellular content of GSH, suggesting that they increase the vulnerability to some biological and chemical insults.

Animals↗

PubMed2000

Effects of pretreatment with SKF-525A on triphenyltin metabolism and toxicity in mice.

The effects of cytochrome P-450 inhibition by alpha-phenyl-alpha-propylbenzeneacetic acid 2-[diethylamino]-ethyl ester hydrochloride (SKF-525A), which inhibits the activity of a number of cytochrome P-450s, on triphenyltin metabolism and toxicity in mice were studied. At 24 h after triphenyltin administration, the triphenyltin levels in the tissues of SKF-525A-pretreated mice were about three times of those in the tissues of SKF-525A-untreated mice and the ratio of metabolites to parent triphenyltin in the tissues of SKF-525A-pretreated mice was lower than those in the tissues of SKF-525A-untreated mice. These data indicate that the pretreatment of SKF-525A decelerated the triphenyltin metabolism and increased triphenyltin accumulation in the tissues of mice. Although triphenyltin did not affect plasma glucose levels of in the SKF-525A-untreated mice, the triphenyltin produced marked hyperglycemia in SKF-525A-pretreated mice. These results suggest that the inhibition of cytochrome P-450 system enzymes by SKF-525A affects the metabolism and toxicity of triphenyltin and has a key role in inducing the hyperglycemic action of triphenyltin, i.e. by increasing triphenyltin accumulation in the mice.

Alanine Transaminase↗

PubMed2001

Toxic effects of butyltin trichloride during early pregnancy in rats.

The objective of this study was to determine the toxic effects of butyltin trichloride (BTCl) during early pregnancy. Following successful mating, female rats were given BTCl by gastric intubation at 0,56,226, or 903 mg/kg on days 0-3 or 4-7 of pregnancy. Female rats were sacrificed on day 20 of pregnancy and fetuses were examined for number, abnormality, mortality, and weight. The maternal body weight gain and food consumption during the administration period was significantly decreased after administration of BTCl at 903 mg/kg on days 0-3 or 4-7 of pregnancy. The pregnancy rate in the BTCl-treated groups was comparable to the control value, regardless of the days on which BTCl was given. The incidence of pre-implantation embryonic loss was not significantly affected after administration of BTCl on days 0-3 or 4-7. In females having implantations, the numbers of corpora lutea, implantations, and live fetuses and the incidences of pre- and postimplantation loss in the groups given BTCl on days 0-3 were comparable to the controls. Although a significant increase in the incidence of postimplantation loss was observed after administration of BTCl on days 4-7 at 56 mg/kg, this change was small and inconsistent across doses and seems unlikely to be toxicologically significant. A significant decrease in weight of female fetuses was found after administration of BTCl at 903 mg/kg on days 0-3 or 4-7. It could be concluded that BTCl treatment during early pregnancy is maternal and developmental toxic at 903 mg/kg.

Abortion, Spontaneous↗

PubMed2002

Effect of organotins on human aromatase activity in vitro.

The interaction between the human aromatase enzyme and some organotins was investigated. Tributyltin (TBT) at 12 and 59 microM and dibutyltin at 74 microM inhibited aromatase activity in vitro but monobutyltin and tri-, di- and monooctyltins were without effect. In four separate kinetic studies of aromatase, the K(m(app)) for testosterone was 0.24, 0.21, 0.16 and 0.24 microM. TBT inhibited aromatase activity by causing the K(m(app)) to be increased without affecting the V(max), indicative of competitive inhibition. Slope and intercept replots confirmed the effect of aromatase on the K(m(app)). Slope replots from three separate kinetic studies provided Ki values for TBT of 64.5, 40.9 and 37.3 microM. Consequently, TBT is a competitive inhibitor of human aromatase with a Ki approximately 300-fold the K(m(app)) value.

Animals↗

PubMed2003

Protective effects of progesterone on implantation failure induced by dibutyltin dichloride in rats.

We previously showed that dibutyltin dichloride (DBTCl) at 7.6 mg/kg and higher on days 0-3 of pregnancy caused implantation failure and a decline in serum progesterone levels in rats and hypothesized that the decline is responsible for the implantation failure. This study was conducted to determine the protective effects of progesterone on the DBTCl-induced implantation failure in rats. Rats were given oral DBTCl at 0, 7.6, or 15.2 mg/kg on days 0-3 of pregnancy and/or subcutaneous progesterone at 2 mg/rat on days 0-8 of pregnancy. The reproductive outcome was determined on day 9 of pregnancy. No effects of administration of progesterone alone on the pregnancy rate and number of implantations were found. The pregnancy rate and number of implantations were significantly decreased after administration of DBTCl alone. The pregnancy rate and number of implantations were higher in the groups given DBTCl and progesterone than the groups given DBTCl alone. The present data indicate that progesterone protects, at least in part, against the DBTCl-induced implantation failure and support our hypothesis that the decline in progesterone levels is a primary mechanism for the implantation failure due to DBTCl.

Animals↗

PubMed1999

Adverse effects of diphenyltin dichloride on initiation and maintenance of pregnancy in rats.

The objective of this study was to characterize the adverse effects of diphenyltin dichloride (DPTCl) during early pregnancy. Following successful mating, female rats were given DPTCl by gastric intubation at 0, 4.1, 8.3, 16.5, 24.8 or 33.0 mg/kg on days 0-3 or days 4-7 of pregnancy. Female rats were sacrificed on day 20 of pregnancy and pregnancy outcome was determined. The pregnancy rate was significantly decreased after administration of DPTCl on days 0-3 at 24.8 mg/kg and on days 4-7 at 33.0 mg/kg. The incidence of preimplantation loss was significantly increased after administration on days 0-3 at 16.5 mg/kg and above and on days 4-7 at 33.0 mg/kg. In females having implantations, the numbers of implantations and live fetuses and the incidences of pre- and postimplantation loss in the groups given DPTCl on days 0-3 were comparable to the controls. The incidence of postimplantation loss was significantly increased after administration of DPTCl on days 4-7 at 33.0 mg/kg. A pair-feeding study revealed no evidence of pre- and postimplantation embryolethality induced by food restriction. It could be concluded that DPTCl during early pregnancy causes early embryonic loss and DPTCl has greater effects on reproduction when administered during earlier than later stages of blastogenesis.

Animals↗

PubMed1999

Determination of bis(tributyltin) oxide by GC--MS with on-line hydride derivatization: application to drug substance analysis.

We report the determination of residual bis(tributyltin) oxide in a drug substance by GC-MS after extraction and on-line conversion to tributyltin hydride. Gas chromatography was performed using a 15 m x 0.25 mm i.d. DB-5 HT column with a temperature program from 100 to 160 degrees C at 15 degrees C min(-1). A mass range of 165-185 amu was monitored with the MS detector. Hydride generation is performed by placing a small amount of solid sodium borohydride in the injection port of a gas chromatograph and injecting samples and standards through this material. Conversion to tributyltin hydride is shown to be quantitative and linear for levels of bis(tributyltin) oxide between 1 and 100 ppm in the drug substance. The use of GC-MS provides sensitive and selective detection of tin containing species and the tin isotope pattern allows for confirmation of the presence of tin in chromatographic peaks. Recovery at 6 ppm was 89% with an injection precision of 6%. The limit of detection for bis(tributyltin) oxide in drug substance is 1 ppm.

Borohydrides↗

PubMed1998

Effects of triphenyltin and other organotins on hepatic monooxygenase system in fish.

The interaction of the organotin fungicide triphenyltin chloride (TPT) with fish microsomal monooxygenase systems has been studied in vitro and in vivo in the marine fish scup (Stenotomus chrysops). In vitro incubation of fish liver microsomes with TPT resulted in the conversion of about 40% of the native total spectral P450 to P420. In addition, a strong concentration-related inhibition of ethoxyresorufin O-deethylase (EROD) activity was observed, with a complete loss at 1.0 mM TPT. Pentoxyresorufin-O-dealkylase (PROD) activity was inhibited only at the highest concentration tested. This suggests either some specificity for the EROD catalyst CYP1A1, or a loss of reductant NADPH cytochrome c reductase as the cause. Further in vitro incubations showed that NADPH, but not NADH, cytochrome c reductase was strongly inhibited at 100 microM TPT and higher. To further investigate this effect, fish were injected with single doses of 5, 25 and 50 microM TPT (1.9, 9.6 and 19.3 mg kg-1 TPT), and 24 and 48 h later, hepatic microsomes were analyzed for total P450 content, EROD activity, NAD(P)H cytochrome c reductase, and the content of three CYP forms. EROD activity tended to be decreased in TPT-treated scup, with the response being stronger after 48 than 24 h. No significant conversion of spectrally determined P450 to cytochrome P420 was found, and cytochrome b5 was not affected. However, both NAD(P)H cytochrome c reductases were significantly inhibited at all concentrations. Immunoblot analysis showed reduction of CYP1A1 content at all doses, being significant at 25 mM after 48 h, but no decrease in CYP3A-like protein, the dominant catalyst of testosterone 6 beta-hydroxylation, nor CYP2B-like protein, the major contributor to indicates significant effects of TPT at high concentrations on fish hepatic CYP1A1 protein, EROD activity and the reductases. TPT seems to act more specifically on CYP1A1 than on other CYP forms. These findings combined with those of our previous studies (Brüschweiler BJ, Würgler FE, Fent K. Environ Toxicol Chem 1996;15:827-735; Fent K, Bucheli TD. Aquat Toxicol 1994;28:107-126; Fent K, Stegeman JJ. Aquat Toxicol 1991;20:159-168; Fent K, Stegeman JJ. Aquat Toxicol 1993;24:219-240) indicate a general degenerative effect of organotins on the fish microsomal monooxygenase system, although some differences are seen between the organotins, and between species. We conclude that these effects of organotins have consequences for use of CYP1A as a biomarker and endocrine disruption.

Animals↗

PubMedDate not supplied

Adverse effects of dibutyltin dichloride on initiation and maintenance of rat pregnancy.

The present study was conducted to evaluate the adverse effects of dibutyltin dichloride (DBTCl) on initiation and maintenance of pregnancy after maternal exposure during early pregnancy in rats. After successful mating, female rats were given DBTCl by gastric intubation on Days 0 to 3 or on Days 4 to 7 of pregnancy at 0, 3.8, 7.6, or 15.2 mg/kg. Food-restricted pregnant rats were given an amount of feed equal to the feed intake of female rats treated with DBTCl at 15.2 mg/kg on Days 0 to 3 or on Days 4 to 7 of pregnancy. Female rats were sacrificed on Day 20 of pregnancy and pregnancy outcome was determined. After administration of DBTCl on Days 0 to 3, the rate of nonpregnant females and the incidence of preimplantation embryonic loss in the 7.6 mg/kg group were significantly higher than those in the control group, and those in the 15.2 mg/kg group were significantly higher than those in the control and pair-fed groups. In females with implantations, the numbers of implantations and live fetuses and the incidence of postimplantation embryonic loss in the groups given DBTCl on Days 0 to 3 were not significantly different from those in the control group. The incidence of postimplantation embryonic loss in the groups given DBTCl on Days 4 to 7 at 7.6 and 15.2 mg/kg was significantly higher than that in the control and pair-fed groups. It can be concluded that DBTCl adversely affects initiation and maintenance of pregnancy when administered during early pregnancy and that the manifestations of the adverse effects of DBTCl vary with the gestational stage at the time of maternal exposure.

Animals↗