Biological activity of organotin compounds--an overview

Nonstoichiometric Direct Arylation Polymerization for Synthesis of Naphthalenediimide-Based π-Conjugated Polymer

High-molar-mass π-conjugated polymers (CPs) are essential for semiconductor applications. However, conventional step-growth cross-coupling polymerizations generally require strict monomer stoichiometry according to the Carothers/Flory theory. Herein, an environmentally benign nonstoichiometric direct arylation polymerization (DArP) is reported that efficiently affords high-molar-mass CPs without employing metal-containing monomers or silver salts. Specifically, 3,4-ethylenedioxythiophene is polymerized using up to a 3-fold excess of 4,9-dibromo-2,7-bis(2-decyltetradecyl)benzo[lmn][3,8]-phenanthroline-1,3,6,8-tetraone in the presence of catalytic Pd2(dba)3/(4-dimethylaminophenyl)di-tert-butylphosphine (AmPhos), affording polymers with number-average molar masses far exceeding the theoretical values predicted using the Carothers/Flory equation. Model reactions involving 2,3-dihydrothieno[3,4-b][1,4]dioxine-5-carbonitrile and 4,9-dibromo-2,7-bis(2-hexyl)benzo[lmn][3,8]-phenanthroline-1,3,6,8-tetraone indicate that the electron-rich AmPhos ligand promotes intramolecular Pd catalyst transfer ("ring-walking"), enabling high polymerization efficiency even under nonstoichiometric conditions. The resulting polymers exhibit negligible structural defects and good solubility in common organic solvents, suggesting regioselective polymerization with minimal side reactions. The proposed nonstoichiometric DArP approach may offer advantages such as reduced polymerization times by using excess monomers that are readily accessible to high-performance semiconducting polymers.

Synthesis of Electron-Deficient BisAzaCoroneneDiimide-Conjugated Polymers by Light-Locking Dynamic Covalent Bonds

We present a novel light-locked dynamic covalent polymerization methodology to synthesize conjugated polymers based on BisAzaCoroneneDiimides (BACDs). This metal-free process converts reversible poly imines into kinetically locked conjugated polymers using visible light, generating minimal side products. By incorporating aldehyde-functionalized comonomers, the approach enables the creation of diverse n-type semiconducting polymers with tunable optical band gaps and low LUMO levels. The polymers exhibit exceptional thermal, electrochemical, and photostability with strong interchain interactions upon electrochemical reduction observed in solution, attributed to the BACD core. Broad absorption from the visible to the near-infrared range underscores their potential in charge and energy transport applications for organic electronics. This scalable, sustainable strategy unlocks access to a versatile class of n-type diimide polymers.

Room-Temperature-Stabilized Alpha Tin Nanocrystals for In Vivo Toxicology Evaluation and Photothermal Therapy Corroborated by FFT Modeling

Herein, we unveil a remarkable finding for synthesizing room-temperature-stable, nontoxic, ultrasmall free-standing diamond cubic tin nanocrystals (α-Sn) with beta forms in the aqueous phase, avoiding conventional approaches that typically use toxic elements or large reactive substrates (Si/InSb) to stabilize α-Sn above 13 °C. Herein, for the first time, we demonstrate the successful synthesis of free-standing alpha tin with extraordinary stability up to 80 °C and in the aqueous phase at room temperature, which was supported by powder X-ray diffraction and X-ray photoelectron spectroscopy characterization methods. This synthetic approach eliminates the need to use hazardous materials, bulky substrates, and elevated temperatures, offering a safer, low-cost, and more sustainable alternative. Prepared α-Sn is characterized by extraordinary NIR absorption and a photothermal efficiency of 42.4%, making it a promising photothermal agent for cancer treatment upon shining low-power (0.5 W) 980 nm NIR light using a CW laser. Using fast Fourier transform weighted bright-field imaging, a mathematical model that foretells the behavior of live malignant cells before and after photothermal treatment has been constructed. Additionally, in vivo studies in rats backed by biochemical and histopathological analyses demonstrated no adverse effects on the vital organs of Wister rats. The unusual biocompatibility of the prepared α-Sn nanocrystals is demonstrated by a low hemolysis index (3.28 ± 0.53%) of the blood, which is far below the permissible limits of 5%. Current research unveils the strong potential of free-standing alpha-tin not only in the area of nanomedicine but also in other domains.

The Environmental Hazards and Treatment of Ship's Domestic Sewage

With the rapid development of the modern shipping field, the damage caused by ship pollution to the global inland waterways and marine ecosystems has attracted extensive attention from the international community. However, there are fewer reviews on the environmental hazards of domestic ship sewage and its treatment, and a systematic summary of the environmental hazards posed by ship domestic sewage and its treatment is lacking. Based on summarizing the various environmental hazards brought about by a ship's domestic sewage and the corresponding treatment methods, this study elaborates, in detail, on the specific hazards of the main toxic and hazardous substances contained in a ship's domestic sewage on the environment and organisms, and the treatment methods of the ship's domestic sewage and their treatment effects, such as membrane bioreactor (MBR). It is also pointed out that MBR has great potential in the direction of ship domestic sewage treatment, and the solution of its membrane pollution and other problems as well as the exploration of the combination of MBR and other treatment methods will become the focus of future research. A theoretical reference is provided for the study of environmental problems caused by domestic sewage from ships and their treatment options.

Trimethyltin chloride induces oxidative damage and apoptosis in chicken liver

Trimethyltin chloride (TMT) is widespread in the environment and is harmful to both humans and animals. In order to investigate the toxicity mechanism of TMT exposure on chicken liver, We established an in vivo experimental model by giving chickens oral administration of different concentrations of TMT dilution solution and vitro experiments of treating leghorn male hepatoma (LMH) cells for 12 h. The results showed that Albumin (ALB), total protein (TP) and alanine aminotransferase (ALT) in the blood of TMT-treated chickens, as well as ALT and aspartate aminotransferase (AST) in the liver, were dose-dependently increased, and different degrees of necrosis of hepatocytes were observed in histology. Meanwhile, TMT exposure led to a significant decrease in glutathione (GSH) content in chicken liver tissues and LMH cells, what's more a significant increase in malondialdehyde (MDA) content in cell supernatants. The expression of apoptosis-related genes Caspase8, Caspase3 and Caspase9 were increased in chicken liver tissues and LMH cells after treated by TMT, and an increased in the percentage of late apoptosis in LMH cells. This suggests that TMT can cause oxidative stress and apoptosis in chicken livers and cells, resulting in liver injury.

Recent advancements of fluorescent tin(IV) complexes in biomedical molecular imaging

In the last few years, tin(IV) complexes have emerged as very attractive candidates in the field of molecular imaging due to their unique photophysical properties. Despite the few reviews published to date covering the chemistry of organotin and tin complexes and their cytotoxic potential, there are no reviews devoted to their live cell imaging properties. Therefore, this feature article summarizes the discussion of the fundamental photophysical properties of fluorescent tin metal complexes focusing on their recent advances in "biomedical molecular imaging". A debate on the design of tin complexes as cellular imaging agents relating to their chemical, electronic and photophysical properties is enclosed. This paper also discusses the imaging applications of tin complexes in cells, tissues, and organisms via confocal and multiphoton imaging for sensing mechanisms in cellular media, bioimaging, and therapeutic labeling. In addition, it explores and explains the current challenges and prospects associated with these tin complexes as emerging luminescent cellular agents for potential clinical use.

Evidence of polystyrene nanoplastic contamination and potential impacts in Mya arenaria clams in the Saint-Lawrence estuary (Canada)

Plastic materials found in the environment are expected to degrade into smaller plastic nanoparticles (NPs) posing a greater toxic risk because they sorb contaminants and pass physiological barriers. Moreover the presence and effects of NPs is difficult to tease out from the contamination background at polluted sites. The purpose of this study was to examine for the presence of polystyrene NPs in feral Mya arenaria clam population near anthropogenic sources of pollution and potential toxic effects. Polystyrene NPs were determined by a newly developed fluorescence-based and size exclusion chromatography methodologies. Clam health status was determined by following changes in air survival time, condition factor, growth, alcohol/aldehyde dehydrogenase (AADH), protein aggregation and lactate dehydrogenase (LDH). In addition, multi-elemental analysis in tissues was also determined. The results revealed that clams collected at 2 polluted sites contained elevated amounts of polystyrene-like NPs between 10 and 110 nm in size based on size exclusion chromatography. Elevated levels of AADH suggest the presence of hydroxylated products and were correlated with plastic NPs in tissues. Moreover, principal component analysis revealed that As, Ca, Cu, Sn and V were closely related to either polystyrene-like NPs in tissues or AADH activity. Although we cannot rule out other pollutants, clams contaminated by polystyrene-like NPs had lower condition, growth rate, air survival time and LDH activity. Increased metal/element contamination reported to sorb onto plastic polymers were also related to NPs in tissues. In conclusion, clams populations close to anthropogenic sources of pollution show evidence of polystyrene-like NPs contamination and could contribute to decreased clam health status.

Recent advances in tin ion detection using fluorometric and colorimetric chemosensors

The innovation of chemosensors for tin ions (Sn4+/Sn2+) has evolved as a key research topic in recent decades, garnering a lot of attention due to their environmental, industrial and biological importance.

Mitochondria-targeted acridine-based dual-channel fluorescence chemosensor for detection of Sn4+ and Cr2O72- ions in water and its application in discriminative detection of cancer cells

The goal of the present work was to fabricate a new low-cost, easy-to-prepare, dual-channel fluorescence chemosensor comprised of acridine-diphenylacetyl moieties (NDA) to enable remarkable Sn⁴⁺ detection in water and biological medium. The resulting NDA-Sn⁴⁺ complex was utilized for the distinguished identification of Cr₂O₇^2- ions from other anions and biomolecules. These investigations involve the absorption, fluorescence, and electrochemical methods for the detection of Sn⁴⁺ and Cr₂O₇^2- ions in pure water. The mechanism for NDA-mediated Sn⁴⁺ detection was experimentally determined by FT-IR, NMR titrations, mass (ESI) analyses, and DFT calculations. The obtained results indicate that the NDA chemosensor possessed excellent performance characteristics including good water solubility and compatibility, quick response time (less than 10 s), high sensitivity (Sn⁴⁺ = 0.268 μM and Cr₂O₇^2- = 0.160 μM), and selectivity against coexisting metals, anions, amino acids, and peptides. The chemosensor NDA induced negligible toxicity in live cells and was successfully utilized as a biomarker for the tracking of Sn⁴⁺ in human normal and cancer cells. More importantly, NDA demonstrates distinguished recognition of Sn⁴⁺ in human cancer cells rather than in normal live cells. Additionally, NDA was shown to act as a mitochondria-targeted probe in FaDu cells.

Mitochondria-targeted dual-channel colorimetric and fluorescence chemosensor for detection of Sn2+ ions in aqueous solution based on aggregation-induced emission and its bioimaging applications

Several fluorescence and colorimetric chemosensory for Sn²⁺ detection in an aqueous media have been reported, but applications remain limited for discriminative Sn²⁺ detection in live human cells and zebrafish larvae. Herein, a mitochondria-targeted Sn²⁺ "turn-on" colorimetric and fluorescence chemosensor, 2CTA, with an aggregation-induced emission (AIE) response was developed. The sensing of Sn²⁺ was enabled by a reduction-enabled binding pathway, with the conversion of -C˭O groups to -C-OH groups at the naphthoquinone moiety. The color changed from light maroon to milky white in a buffered aqueous solution. The chemosensor 2CTA possessed the excellent characteristics of good water solubility, fast response (less than 10 s), and high sensitivity (79 nM) and selectivity for Sn²⁺ over other metal ions, amino acids, and peptides. The proposed binding mechanism was experimentally verified by means of FT-IR and NMR studies. The chemosensor 2CTA was successfully employed to recognize Sn²⁺ in live human cells and in zebrafish larvae. In addition, a colocalization study proved that the chemosensor had the ability to target mitochondria and overlapped almost completely with MitoTracker Red. Furthermore, a bioimaging study of live cells demonstrated the discriminative detection of Sn²⁺ in human cancer cells and the practical applications of 2CTA in biological systems.

Toxicity of organotin compounds and the ecological risk of organic tin with co-existing contaminants in aquatic organisms

Although organotin (OT) use is restricted worldwide, with the development of industry and agriculture, a large amount of OT is still discharged into aquatic environments. These OTs may interact with other pollutants that cause adverse biological effects (through bioaccumulation and/or toxicity), resulting in combined toxicity. Most research on OTs have focused on the exposure of a single analyte. Information on the toxicity of OTs and coexisting pollutants is quite limited, but is developing rapidly. This is the first review paper evaluating the current state of knowledge on the combined effects of OTs with co-pollutants. This paper reviews 1) the degradation of organotin; and 2) the combined toxicity of OTs and emerging pollutants (EP), heavy metals, and organic pollutants. Future research needs are discussed to better understand the risks associated with co-exposure to OT pollutants.

Preparation of a new fluorescence nanochemosensor for Sn(II) ions by a modified nanoprecipitation method

A new dialdehyde was designed and synthesized containing naphthalene groups, and then its macrocycle was prepared with 1,4-diaminobuthan. A modified nanoprecipitation method has been reported for the preparation of the nanoparticles. In this method, to obtain nanoparticles with small particle sizes, the nucleation rate was increased with decreasing of the mixing time. The organic nanoparticles were used for turn-off fluorescence response of low concentration of Sn²⁺ ions over cations such as Cs⁺, K⁺, Na⁺, Ba²⁺, Ca²⁺, Mg²⁺, Al³⁺, Pb^2+, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Fe²⁺, Mn²⁺, Ag⁺, Cd²⁺, and Hg²⁺ and ions in aqueous buffer solution. The limit of detection was 5.4 nM.

Assessing the Association of Mitochondrial Function and Inflammasome Activation in Murine Macrophages Exposed to Select Mitotoxic Tri-Organotin Compounds

BACKGROUND

Mitochondrial function is implicated as a target of environmental toxicants and found in disease or injury models, contributing to acute and chronic inflammation. One mechanism by which mitochondrial damage can propagate inflammation is via activation of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family, pyrin domain-containing receptor (NLRP)3 inflammasome, a protein complex that processes mature interleukin (IL)-1β. IL-1β plays an important role in the innate immune response and dysregulation is associated with autoinflammatory disorders.

OBJECTIVE

The objective was to evaluate whether mitochondrial toxicants recruit inflammasome activation and IL-1β processing.

METHOD

Murine macrophages (RAW 264.7) exposed to tri-organotins (triethyltin bromide (TETBr), trimethyltin hydroxide (TMTOH), triphenyltin hydroxide (TPTOH), bis(tributyltin)oxide) [Bis(TBT)Ox] were examined for pro-inflammatory cytokine induction. TMTOH and TETBr were examined in RAW 264.7 and bone marrow-derived macrophages for mitochondrial bioenergetics, reactive oxygen species (ROS) production, and inflammasome activation via visualization of aggregate formation, caspase-1 flow cytometry, IL-1β enzyme-linked immunosorbent assay and Western blots, and microRNA (miRNA) and mRNA arrays.

RESULTS

TETBr and TMTOH induced inflammasome aggregate formation and IL-1β release in lipopolysaccharide (LPS)-primed macrophages. Mitochondrial bioenergetics and mitochondrial ROS were suppressed. Il1a and Il1b induction with LPS or LPS+ATP challenge was diminished. Differential miRNA and mRNA profiles were observed. Lower miR-151-3p targeted cyclic adenosine monophosphate (cAMP)-mediated and AMP-activated protein kinase signaling pathways; higher miR-6909-5p, miR-7044-5p, and miR-7686-5p targeted Wnt beta-catenin signaling, retinoic acid receptor activation, apoptosis, signal transducer and activator of transcription 3, IL-22, IL-12, and IL-10 signaling. Functional enrichment analysis identified apoptosis and cell survival canonical pathways.

CONCLUSION

Select mitotoxic tri-organotins disrupted murine macrophage transcriptional response to LPS, yet triggered inflammasome activation. The differential response pattern suggested unique functional changes in the inflammatory response that may translate to suppressed host defense or prolong inflammation. We posit a framework to examine immune cell effects of environmental mitotoxic compounds for adverse health outcomes. https://doi.org/10.1289/EHP8314.

Influence of triphenyltin on morphologic abnormalities and the thyroid hormone system in early-stage zebrafish (Danio rerio)

In the present study, we assessed the negative effects of triphenyltin (TPT) on zebrafish (Danio rerio) by exposing embryos and early-stage larvae to various concentrations of TPT from 2 h after fertilization (haf) until 30 days after hatching (dah). Whether test groups were fed or fasted during ecotoxicity studies using fish models has varied historically, and whether this experimental condition influences test results is unknown. Here, we confirmed that the lethal concentration of TPT to embryo and early-stage larvae (i.e., 3 dah or younger) showed in fed (lowest observed effect concentration (LOEC); 6.34 μg/L) and fasted (LOEC; 6.84 μg/L) groups. In addition, 84% and 100% of the larvae in the 2.95 and 6.64 μg/L exposure groups, respectively, had uninflated swim bladders; all affected larvae died within 9 dah. This finding suggests that morphologic abnormalities in early larval zebrafish are useful as endpoints for predicting the lethality of chemical substances after hatching. We then assessed the expression of several genes in the thyroid hormone pathway, which regulates swim bladder development in many fish species, including zebrafish. Larvae exposed to 6.64 μg/L TPT showed significant increases in the mRNA expression levels of thyroid hormone receptor α (trα) and trβ but not of thyroid stimulating hormone β subunit. These findings suggest that TPT disrupts the thyroid system in zebrafish.

Bone Disruption and Environmental Pollutants

BACKGROUND

Endocrine Disrupting Chemicals (EDCs) are ubiquitous and may significantly contribute in environmental pollution, thus contaminating humans and wildlife. Environmental pollutants could interfere with bone homeostasis by means of different mechanisms, which include hormonal imbalance, direct osteoblasts toxicity and enanchment of osteoclasts activity, thus leading to osteopenia or osteoporosis. Among these, bisphenols, dioxins, polycyclic aromatic hydrocarbons, polychlorobiphenyls, poly- and perfluoroalkyls, phthalates, parabens, organotins and cadmium may play a role in bone distuption.

METHODS

PubMed/MEDLINE, ISI-web of knowledge and Google scholar databases were searched for medical subject headings terms and free-text word related to the aforementioned classes of chemicals and bone metabolism and remodelling for better clarifying and understanding the main mechanisms of bone disruption.

RESULTS

Several of EDCs act as xenoestrogens. Considering that estrogens play a significant role in regulating bone remodeling, most of these chemicals generate hormonal imbalance with possible detrimental consequences on bone tissue structure and its mechanical and non-mechanical properties.

DISCUSSION

A lot of evidences about bone distruptors came from in vitro studies or animal models, and conduct to equivocal results. In addition, a few data derived form humans and most of these data focused on the impact of EDCs on bone mineral density without considering their influence on long-term fracture risk. Moreover, it should be taken into account that humans are exposed to a mixture of EDCs and the final effect on bone metabolism might be the result of either a synergism or antagonist effects among them. Age of first exposure, cumulative dose exposure over time, and the usually observed non-monotonic dose-response curve for EDCs should be considered as other important variable influencing the final effect on bone metabolism.

CONCLUSION

Taking into account these variables, observational studies are needed to better analyze this issue both for echological purpose and to preserve bone health.

Triphenyltin exposure alters the antioxidant system, energy metabolism and the expression of genes related to physiological stress in zebrafish (Danio rerio)

The adverse influences of triphenyltin (TPT) on aquatic system have been of great concern due to their widespread use and ubiquity in water environment. Here, zebrafish larvae (7 days after hatching) were exposed to TPT for 14 days to study its toxicity on the antioxidant system, energy metabolism and the expression of genes related to physiological stress. Results shows that the oxidative stress was generated in fish larvae exposed to TPT with higher concentrations (10 and/or 100 ng/l), and the energy metabolic parameters (RNA/DNA ratio, Na + -K + -ATPase) were significantly inhibited in fish exposed to 100 ng/l TPT. Additional, the expression levels of genes related to physiological stress were up-regulated in a dose-dependent manner, including heat shock protein70 (hsp70) and metallothionein (mt). Moreover, the PERK-eIF2α pathway was found as the main branch activated by TPT exposure in fish larvae. Thus, TPT-induced antioxidant responses, energy metabolism disorder and physiological stress in fish larvae were reflected by the parameters measured, which could provide some useful information for full understanding the exact mechanisms of TPT toxicity.

Influences of Salinity and Organic Compounds on Embryo Development in Three Medaka Oryzias Congeners with Habitats Ranging from Freshwater to Marine

To clarify whether Oryzias congeners, including freshwater, brackish water, and marine medaka, would be useful models for evaluating environmental chemical effects in various aquatic ecosystems, we examined the influence of salinity on their embryo development. We also compared the toxicity values of the organotin compounds triphenyltin and tributyltin, which remain pollutants of marine and freshwater ecosystems, between Oryzias latipes (freshwater), Oryzias melastigma (brackish water), and Oryzias javanicus (saltwater). Hatching and survival rates of O. latipes were significantly decreased at a salinity of 34, whereas O. melastigma and O. javanicus were adaptable to various salinities from freshwater to seawater. The lowest observed effect concentrations of organotin compounds for survival and embryo development were the similar in the three species. The similarity of the species' responses to organotin compounds indicated that Oryzias congeners are useful for ecological risk assessment of chemicals in a range of aquatic ecosystems, from freshwater to marine.

Dibromidobis(3-bromobenzyl-κC)(4,7-diphenyl-1,10-phenanthroline-κ2 N,N′)tin(IV)

In the title compound, [SnBr2(C7H6Br)2(C24H16N2)], the Sn atom is coordinated to a 4,7-diphenyl-1,10-phenanthroline, two 3-bromobenzyl and two bromide ligands, leading to a six-coordinate C2Br2N2 donor set. The bromobenzyl ligands are trans to each other, while the Br anions are in a cis arrangement. One of the two 3-bromobenzyl ligands is disordered over two similar conformations, with occupancies of 0.7078 (18) and 0.2922 (18). In the crystal, molecules are linked into centrosymmetric dimers by Br...Br halogen bonds [3.5972 (12) Å], which are linked into a supramolecular layer in the ac plane by weak intermolecular C—H...Br interactions.

RIP1 and RIP3 contribute to Tributyltin-induced toxicity in vitro and in vivo

Tributyltin (TBT), a widely distributed environmental pollutant, is toxic to animals and human beings. Although its toxicity, especially the immunosuppressive effect, has been reported a lot, the underlying molecular mechanisms are still unclear. In this study, we investigated the mechanisms of TBT-induced cytotoxicity both in vitro and in vivo. TBT induced cell death in both J774A.1 macrophages and mouse bone marrow-derived macrophages (BMDMs) as measured by the LDH and Annexin V-FITC/PI dual staining assays. Pretreatment with RIP1 inhibitor Necrostatin-1 (Nec-1) or transfection with Rip1 siRNA significantly suppressed TBT-induced cytotoxicity in J774A.1 macrophages or human embryonic kidney cell line (HEK293 cells). TBT-induced cell death was also markedly inhibited in RIP3^-/- BMDMs. In agreement with in vitro results, TBT-induced in vivo immunotoxic effects including leukocyte depletion and thymus atrophy were significantly attenuated in RIP3^-/- mice or WT mice treated with Nec-1. Notably, the mortality rate induced by TBT was remarkably reduced in RIP3^-/- mice (100% vs. 12.5% lethality) or Nec-1-treated mice (100% vs. 59.2% lethality) respectively. These results reveal a critical role of RIP1 and RIP3 in TBT-induced toxicity both in vitro and in vivo.

[Neurotoxicity Mechanism of Environmental Chemicals and Its Evaluation System]

　It is pivotal to assess the toxicity and safety of chemicals, including medicines, in the research field of environmental health science. Here we introduce neurotoxic mechanisms in mammals of environmental organotin and Parkinson's disease-related chemicals. We clarified that low concentrations of tributyltin decrease α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptor subunit GluA2 (GluR2) expression, leading to the vulnerability of cultured neurons. That is, tributyltin reduces GluA2 prior to neuronal death. This GluA2 decrease can be used as a sensitive evaluation index of neurotoxicity, since low levels of certain chemicals, for example some agrochemicals, decrease GluA2 expression. We also elucidated the mechanisms of abnormal protein metabolism induced by low levels of two Parkinson's disease-related chemicals: 1-methyl-4-phenylpyridinium ion (MPP⁺) and 1,2,3,4-tetrahydroisoquinoline derivatives. It is expected that these findings will become clues in accurately evaluating the toxicity of chemicals and/or in investigating the causes of disease.

Tributyltin stimulates synthesis of interferon gamma and tumor necrosis factor alpha in human lymphocytes

Tributyltin (TBT) is found in human blood and other tissues and thus is of considerable concern as to its effects on human health. Previous studies have demonstrated that TBT has detrimental effects on immune function. Recently, we found that exposures to TBT caused increased secretion of two important proinflammatory cytokines, tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). Elevation of either of these cytokines has the potential to cause chronic inflammation, which is an important factor in a number of diseases including cancer. The current study examined the mechanism of TBT-induced elevations of TNFα and IFNγ secretion and found that the p38 mitogen-activated protein kinase pathway was essential to the ability of TBT to stimulate secretion. Additionally, this study demonstrated that increased secretion of these cytokines was due to TBT-induced increases in their overall synthesis, rather than simply being due to an increase in the release of already formed proteins. The TBT-induced increases in synthesis were evident within 6 hours of exposure. The p38 mitogen-activated protein kinase pathway is also necessary for the TBT-induced increases in both TNFα and IFNγ synthesis. The role of increased transcription of TNFα and IFNγ mRNA in response to TBT exposures as a possible explanation for the increased synthesis of these cytokines was also examined. It was found that increased mRNA levels did not appear to explain fully the increases in either TNFα or IFNγ synthesis. Thus, TBT is able to increase secretion of two important proinflammatory cytokines by increasing their synthesis.

Tributyltin induces epigenetic changes and decreases the expression of nuclear respiratory factor-1

Tributyltin (TBT), a common organotin environmental pollutant, has been widely used as a component of marine antifouling paints. We previously reported that exposure to TBT inhibits the expression and DNA binding of nuclear respiratory factor-1 (NRF-1) and causes neurotoxicity. In the present study, we focused on the epigenetic effects of TBT and investigated whether TBT decreases NRF-1 expression via epigenetic modifications in SH-SY5Y human neuroblastoma cells. First, we found that exposure to 300 nM TBT decreases NRF-1 expression. We examined epigenetic changes induced by TBT, and showed that TBT causes hypermethylation of the NRF-1 promoter region, increases the amount of methyl-CpG-binding protein 2 (MeCP2) bound to the NRF-1 promoter, and alters the expression of DNA methyltransferases and ten-eleven translocation (TET) demethylation enzymes. These results suggest that epigenetic changes play an important role in regulation of NRF-1 expression. Next, we investigated effect of NRF-1 expression decrease on cells, and TBT reduces mitochondrial membrane potential and overexpression of NRF-1 rescued this reduction in membrane potential. Thus, we suggested that NRF-1 is important for maintaining mitochondrial membrane potential. Our study indicates that TBT causes epigenetic changes such as hypermethylation, which increases recruitment of MeCP2 to the NRF-1 promoter and probably lead to decreased of NRF-1 expression and mitochondrial membrane potential. Therefore, this research provides new evidence of the epigenetic action caused by organotin.

Effects of triphenyltin on reproduction in Japanese medaka (Oryzias latipes) across two generations

Triphenyltin (TPT) is an organotin compound used in marine anti-fouling coatings to prevent the attachment and growth of marine organisms, and it has negative effects on aquatic organisms. TPT is still detected at low concentrations, although its use has been prohibited at least in the European Community and is restricted in Japan as well. Studies using Japanese medaka (Oryzias latipes) indicate that TPT has the potential to inhibit reproduction. Although TPT is detected in many aquatic ecosystems, the multi-generational impact of TPT remains unknown. We investigated the two-generational effects of TPT on Japanese medaka and examined the relationships of several such effects between the F0 and F1 generations. Suppression of fecundity was observed in both generations, and fertility and growth were inhibited in the F1 generation. Moreover, delayed hatching and lower hatchability were observed in F1 embryos. Importantly, the value of the lowest observed effect concentration (LOEC) for these influences in F1 was lower than that in F0: that is, the LOEC values of fecundity and mortality were 3.2μg/L in the F0 generation and 1.0μg/L in the F1 generation. Fertility was not affected by TPT in F0, whereas it was significantly suppressed in the 1.0μg/L-exposure group of the F1 generation. Our results provide the first evidence of the effects of TPT on reproduction in a teleost fish across two generations, highlighting the concern that TPT could affect reproduction and mortality at decreasing concentrations in temporally overlapping generations.

In vitro evaluation of the cytotoxic and bactericidal mechanism of the commonly used pesticide triphenyltin hydroxide

Triphenyltin hydroxide (TPTH) is a widely used pesticide that is highly toxic to a variety of organisms including humans and a potential contender for the environmental pollutant. In the present study, the cytotoxic mechanism of TPTH on mammalian cells was analyzed using HeLa cells and the antibacterial activity was analyzed using B. subtilis and E. coli cells. TPTH inhibited the growth of HeLa cells with a half-maximal inhibitory concentration of 0.25 μM and induced mitotic arrest. Immunofluorescence microscopy analysis showed that TPTH caused strong depolymerization of interphase microtubules and spindle abnormality with the appearance of colchicine type mitosis and condensed chromosome. TPTH exhibited high affinity for tubulin with a dissociation constant of 2.3 μM and inhibited the in vitro microtubule assembly in the presence of glutamate as well as microtubule-associated proteins. Results from the molecular docking and in vitro experiments implied that TPTH may have an overlapping binding site with colchicine on tubulin with a distance of about 11 Å between them. TPTH also binds to DNA at the A-T rich region of the minor groove. The data presented in the study revealed that the toxicity of TPTH in mammalian cells is mediated through its interactions with DNA and its strong depolymerizing activity on tubulin. However, its antibacterial activity was not through FtsZ, the prokaryotic homolog of tubulin but perhaps through its interactions with DNA.

Effects of adenylyl cyclase and protein kinase A inhibition on signaling enzymes in natural killer cells: comparison to tributyltin

Natural killer (NK) cells are lymphocytes capable of destroying tumor cells and virally-infected cells without prior sensitization. In a previous study, we found that inhibition of adenylyl cyclase (AC) or cAMP-dependent protein kinase (PKA) decreased the ability of NK cells to destroy tumor cells. We also found that the environmental contaminant tributyltin (TBT), at concentrations of 300 500 nM, decreased tumor-cell lysis by NK cells, as well as their intracellular levels of cAMP. This suggested that the decreases in cAMP associated with TBT (300 500 nM) may, in part, be responsible for loss of cytotoxic function. Here, we investigated the effects of inhibition of AC or PKA on enzymes that are required in the NK tumorolytic process and compared them to those of TBT exposure. The enzymes studied were: the protein tyrosine kinase (PTK), syk; phospholipase C gamma1 (PLCg1); and the mitogen activated protein kinase (MAPK), p44/42. Exposure of NK cells to the AC inhibitor 2?,5?-dideoxyadenosine (DDA) significantly increased the total level of PLCg1 by 67% after 60 min and the level of p44/42 by about 30%. Exposure to the PKA inhibitor H-89 significantly increased the levels of the phosphorylated (activated) p44/42 (90%) after 60 min. Exposure to TBT increased the levels of PLCg1 by about 50%. Previously, we found that exposure to TBT increased the phosphorylation of p44/42 within 5 min. These results indicate that AC inhibition caused alterations of the levels of key enzymes, while decreased PKA activity caused an increase in p44/42 activation. They also suggest that the effects of decreased levels of cAMP on these key cytotoxic signaling proteins may overlap, to a very limited extent, with those of TBT.

Cytotoxicity of organotin compounds in different cultured cell lines

Organotin as monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) compounds are used as fungicides and anti-fouling compounds; small amounts are added to the new European Euro bills. Little is known about the toxicological profile of these compounds uptake and metabolism. We, therefore, studied the cytotoxicity of these agents in different cell lines, i.e., liver HepG2, renal LLCMK2 and ocular CEC cells. As a measure of cell growth and death, the neutral red assay and the release of LDH into the medium were used. IC50 values for growth inhibition by TBT were calculated as 160 nM in LLC-MK2, 150 nM in HepG2 and 180 nM in CEC cells; for DBT the corresponding values were higher, i.e., 500 nM DBT for LLC-MK2 cells, 300 nM for HepG2 cells and 220 nM for CE cells. ED50 values for LDH release indicating disturbances of the outer cell membrane was > 250 nM for TBT and > 350 nM for DBT in all cells. MBT was not toxic in concentrations up to 500 nM. Electron microscopic studies of cells treated with 300 nM tributyltin indicated severe mitochondrial damage with much less effect seen in other cell structures. We conclude that no differences exist between different cell lines that may serve as examples of tissues relevant for organotin exposure (eye), metabolism (liver) and specific metalloid damage (kidney). Growth inhibition was affected at organotin concentrations between 150 and 500 nM. This concentration is approximately 70-200 fold higher than values estimated in environmental samples.

Toxicity of tributyltin (TBT) to the freshwater planarian Schmidtea mediterranea

The freshwater planarian Schmidtea mediterranea, one of the best characterized animal models for regeneration research and developmental biology, is being recognised as a useful species for ecotoxicological studies. Sensitive endpoints related to planarians' behaviour and regeneration can be easily evaluated after exposure to environmental stressors. In this work the sensitivity of S. mediterranea to a gradient of environmentally relevant concentrations of TBT was studied using multiple endpoints like survival, locomotion, head regeneration and DNA damage. In addition, a feeding assay based on planarian's predatory behaviour was performed. Results indicated that TBT is toxic to planarians with LC50's of 1.87 μg L(-1) Sn and 1.31 μg L(-1) Sn at 48 h and 96 h of exposure respectively. Sub-lethal exposures to TBT significantly reduced locomotion and feeding, delayed head regeneration and caused DNA damage in planarians. The behavioural endpoints (feeding and locomotion) and head regeneration were the most sensitive parameters followed by DNA damage. Similar to other aquatic model organisms, S. mediterranea showed high sensitivity towards TBT exposure. Based on our results, and though further research is required concerning their sensitivity to other pollutants, the use of freshwater planarians as a model species in ecotoxicology is discussed.

A through bond energy transfer based ratiometric probe for fluorescent imaging of Sn2+ ions in living cells

A 4-(naphthalen-1-ylethynyl) aniline appended rhodamine based fluorescent chemosensor ‘NAP-RD’ is synthesized which undergoes through bond energy transfer in the presence of Sn²⁺ ions in mixed aqueous media.

Self-decontaminating photocatalytic zinc oxide nanorod coatings for prevention of marine microfouling: a mesocosm study

The antifouling (AF) properties of zinc oxide (ZnO) nanorod coated glass substrata were investigated in an out-door mesocosm experiment under natural sunlight (14:10 light: dark photoperiod) over a period of five days. The total bacterial density (a six-fold reduction) and viability (a three-fold reduction) was significantly reduced by nanocoatings in the presence of sunlight. In the absence of sunlight, coated and control substrata were colonized equally by bacteria. MiSeq Illumina sequencing of 16S rRNA genes revealed distinct bacterial communities on the nanocoated and control substrata in the presence and absence of light. Diatom communities also varied on nanocoated substrata in the presence and the absence of light. The observed AF activity of the ZnO nanocoatings is attributed to the formation of reactive oxygen species (ROS) through photocatalysis in the presence of sunlight. These nanocoatings are a significant step towards the production of an environmentally friendly AF coating that utilizes a sustainable supply of sunlight.

Naphthothiazole-based highly selective and sensitive fluorescent and colorimetric chemosensor for detection of pollutant metal ions

The presented small molecule sensor can be used successfully for selective detection of Zn²⁺ and Sn²⁺ ions in aqueous media.

Secretion of interferon gamma from human immune cells is altered by exposure to tributyltin and dibutyltin

Tributyltin (TBT) and dibutyltin (DBT) are widespread environmental contaminants found in food, beverages, and human blood samples. Both of these butyltins (BTs) interfere with the ability of human natural killer (NK) cells to lyse target cells and alter secretion of the pro-inflammatory cytokine tumor necrosis factor alpha (TNFα) from human immune cells in vitro. The capacity of BTs to interfere with secretion of other pro-inflammatory cytokines has not been examined. Interferon gamma (IFNγ) is a modulator of adaptive and innate immune responses, playing an important role in overall immune competence. This study shows that both TBT and DBT alter secretion of IFNγ from human immune cells. Peripheral blood cell preparations that were increasingly reconstituted were used to determine if exposures to either TBT or DBT affected IFNγ secretion and how the makeup of the cell preparation influenced that effect. IFNγ secretion was examined after 24 h, 48 h, and 6 day exposures to TBT (200 - 2.5 nM) and DBT (5 - 0.05 µM) in highly enriched human NK cells, a monocyte-depleted preparation of PBMCs, and monocyte-containing PBMCs. Both BTs altered IFNγ secretion from immune cells at most of the conditions tested (either increasing or decreasing secretion). However, there was significant variability among donors as to the concentrations and time points that showed changes as well as the baseline secretion of IFNγ. The majority of donors showed an increase in IFNγ secretion in response to at least one concentration of TBT or DBT at a minimum of one length of exposure.

Effects of butyltins on mitogen-activated-protein kinase kinase kinase and Ras activity in human natural killer cells

Butyltins (BTs) contaminate the environment and are found in human blood. BTs, tributyltin (TBT) and dibutyltin (DBT) diminish the cytotoxic function and levels of key proteins of human natural killer (NK) cells. NK cells are an initial immune defense against tumors, virally infected cells and antibody-coated cells and thus critical to human health. The signaling pathways that regulate NK cell functions include mitogen-activated protein kinases (MAPKs). Studies have shown that exposure to BTs leads to activation of specific MAPKs and MAPK kinases (MAP2Ks) in human NK cells. MAP2K kinases (MAP3Ks) are upstream activators of MAP2Ks, which then activate MAPKs. The current study examined if BT-induced activation of MAP3Ks was responsible for MAP2K and thus, MAPK activation. This study examines the effects of TBT and DBT on the total levels of two MAP3Ks, c-Raf and ASK1, as well as activating and inhibitory phosphorylation sites on these MAP3Ks. In addition, the immediate upstream activator of c-Raf, Ras, was examined for BT-induced alterations. Our results show significant activation of the MAP3K, c-Raf, in human NK cells within 10 min of TBT exposure and the MAP3K, ASK1, after 1 h exposures to TBT. In addition, our results suggest that both TBT and DBT affect the regulation of c-Raf.

Effect of Lactational Exposure to Tributyltin Chloride on Innate Immunodefenses in the F1 Generation in Mice

We examined the effect of lactational exposure to tributyltin on innate immunodefenses in the F1 generation using in vivo and in vitro experiments. Pregnant C57BL/6 mice were given drinking water containing 0, 15, or 50 microg/ml of tributyltin chloride (TBTCl) from parturition to weaning. At weaning time, offspring were inoculated with Escherichia coli K-12, and bacterial clearances from the peritoneal cavity and spleen were examined. In vivo infection experiments indicated that bacterial clearance was significantly depressed in offspring breast-fed by dams exposed to 15 microg/ml of TBTCl (15 ppm F1), but not in offspring by dams exposed to 50 microg/ml of TBTCl (50 ppm F1). In vitro functional assays revealed that the killing activity of neutrophils decreased significantly in 15 ppm F1, but not in 50 ppm F1. We suggest that lactational exposure to TBT impairs innate immunodefenses in the F1 generation against non-pathogenic bacterial infection.

Toxicity of tributyltin (TBT) to terrestrial organisms and its species sensitivity distribution

The contamination of the terrestrial environment by disposal of tributyltin (TBT) by contaminated harbour sediments, sewage sludge and/or biocide products has been raising concerns and it may pose a risk to soil invertebrates and plants. This study aimed to improve the amount and quality of data for TBT toxicity in soils in order to assess the ecological risk of TBT to the terrestrial ecosystems. For this, bioassays were performed with the species Porcellionides pruinosus, Folsomia candida, Brassica rapa and Triticum aestivum to evaluate the toxic effects of TBT (as chloride) on these species. Additionally, this study contributed to increase the amount of data concerning TBT toxicity on soil dwelling organisms. The results showed a dose-response relationship between TBT concentration and the increase of toxicity in all species tested. These results were collated with results from literature to construct species sensitivity distributions (SSDs) and to calculate the hazardous concentration at 5% (HC₅) for all data, for each type of soil and TBT formulation used. The HC₅ value for TBT in soil was 2.06 mg TBT/kg soil dw. Little information is available concerning the concentrations of TBT in soils. In addition the predicted no-effect concentration (PNEC) value was determined to be 30 μg/kg soil. Only one study was found referring to TBT contaminated soils, and where TBT concentrations were lower than 0.024 μg TBT/kg for the wetland soil. Therefore it can be concluded that the real TBT concentrations determined represent low risk for environmental effects. In conclusion, the construction of SSDs and the calculation of HC5 using all the data available showed to be a more suitable method rather than the construction of several SSDs for each soil and TBT types. Further investigations concerning TBT concentrations and toxicity on soil organisms need to be performed to increase data and improve risk calculations.

Exposure to tributyltin induces endoplasmic reticulum stress and the unfolded protein response in zebrafish

Tributyltin (TBT) is a major marine contaminant and causes endocrine disruption, hepatotoxicity, immunotoxicity, and neurotoxicity. However, the molecular mechanisms underlying the toxicity of TBT have not been fully elucidated. We examined whether exposure to TBT induces the endoplasmic reticulum (ER) stress response in zebrafish, a model organism. Zebrafish-derived BRF41 fibroblast cells were exposed to 0.5 or 1 μM TBT for 0.5-16 h and subsequently lysed and immunoblotted to detect ER stress-related proteins. Zebrafish embryos, grown until 32 h post fertilization (hpf), were exposed to 1 μM TBT for 16 h and used in whole mount in situ hybridization and immunohistochemistry to visualize the expression of ER chaperones and an ER stress-related apoptosis factor. Exposure of the BRF41 cells to TBT caused phosphorylation of the zebrafish homolog of protein kinase RNA-activated-like ER kinase (PERK), eukaryotic translation initiation factor 2 alpha (eIF2α), and inositol-requiring enzyme 1 (IRE1), characteristic splicing of X-box binding protein 1 (XBP1) mRNA, and enhanced expression of activating transcription factor 4 (ATF4) protein. In TBT-exposed zebrafish embryos, ectopic expression of the gene encoding zebrafish homolog of the 78 kDa glucose-regulating protein (GRP78) and gene encoding CCAAT/enhancer-binding protein homologous protein (CHOP) was detected in the precursors of the neuromast, which is a sensory organ for detecting water flow and vibration. Our in vitro and in vivo studies revealed that exposure of zebrafish to TBT induces the ER stress response via activation of both the PERK-eIF2α and IRE1-XBP1 pathways of the unfolded protein response (UPR) in an organ-specific manner.