Medicinal properties of organotin compounds and their limitations caused by toxicity

Injectable and in situ foaming shape-adaptive porous Bio-based polyurethane scaffold used for cartilage regeneration

Irregular articular cartilage injury is a common type of joint trauma, often resulting from intense impacts and other factors that lead to irregularly shaped wounds, the limited regenerative capacity of cartilage and the mismatched shape of the scaffods have contributed to unsatisfactory therapeutic outcomes. While injectable materials are a traditional solution to adapt to irregular cartilage defects, they have limitations, and injectable materials often lack the porous microstructures favorable for the rapid proliferation of cartilage cells. In this study, an injectable porous polyurethane scaffold named PU-BDO-Gelatin-Foam (PUBGF) was prepared. After injection into cartilage defects, PUBGF forms in situ at the site of the defect and exhibits a dynamic microstructure during the initial two weeks. This dynamic microstructure endows the scaffold with the ability to retain substances within its interior, thereby enhancing its capacity to promote chondrogenesis. Furthermore, the chondral repair efficacy of PUBGF was validated by directly injecting it into rat articular cartilage injury sites. The injectable PUBGF scaffold demonstrates a superior potential for promoting the repair of cartilage defects when compared to traditional porous polyurethane scaffolds. The substance retention ability of this injectable porous scaffold makes it a promising option for clinical applications.

Applications of low-valent compounds with heavy group-14 elements

Over the last two decades, the low-valent compounds of group-14 elements have received significant attention in several fields of chemistry owing to their unique electronic properties. The low-valent group-14 species include tetrylenes, tetryliumylidene, tetrylones, dimetallenes and dimetallynes. These low-valent group-14 species have shown applications in various areas such as organic transformations (hydroboration, cyanosilylation, N-functionalisation of amines, and hydroamination), small molecule activation (e.g. P4, As4, CO2, CO, H2, alkene, and alkyne) and materials. This review presents an in-depth discussion on low-valent group-14 species-catalyzed reactions, including polymerization of rac-lactide, L-lactide, DL-lactide, and caprolactone, followed by their photophysical properties (phosphorescence and fluorescence), thin film deposition (atomic layer deposition and vapor phase deposition), and medicinal applications. This review concisely summarizes current developments of low-valent heavier group-14 compounds, covering synthetic methodologies, structural aspects, and their applications in various fields of chemistry. Finally, their opportunities and challenges are examined and emphasized.

Organotin (IV) Dithiocarbamate Compounds as Anticancer Agents: A Review of Syntheses and Cytotoxicity Studies

Organotin (IV) dithiocarbamate has recently received attention as a therapeutic agent among organotin (IV) compounds. The individual properties of the organotin (IV) and dithiocarbamate moieties in the hybrid complex form a synergy of action that stimulates increased biological activity. Organotin (IV) components have been shown to play a crucial role in cytotoxicity. The biological effects of organotin compounds are believed to be influenced by the number of Sn-C bonds and the number and nature of alkyl or aryl substituents within the organotin structure. Ligands target and react with molecules while preventing unwanted changes in the biomolecules. Organotin (IV) dithiocarbamate compounds have also been shown to have a broad range of cellular, biochemical, and molecular effects, with their toxicity largely determined by their structure. Continuing the investigation of the cytotoxicity of organotin (IV) dithiocarbamates, this mini-review delves into the appropriate method for synthesis and discusses the elemental and spectroscopic analyses and potential cytotoxic effects of these compounds from articles published since 2010.

Tin(II) and Tin(IV) Complexes Incorporating the Oxygen Tripodal Ligands [(η5-C5R5)Co{P(OEt)2O}3]-, (R = H, Me; Et = -C2H5) as Potent Inflammatory Mediator Inhibitors: Cytotoxic Properties and Biological Activities against the Platelet-Activating Factor (PAF) and Thrombin

Metal complexes displaying antiplatelet properties is a promising research area. In our methodology, Platelet-Activating Factor (PAF), the most potent lipid pro-inflammatory mediator, serves as a biological probe. The antiplatelet activity is exerted by the inhibition of the PAF-induced aggregation in washed rabbit platelets (WRPs) and in rabbit plasma rich in platelets (rPRPs). Herein, the synthesis and biological investigation of a series of organometallic tin(II) and tin(IV) complexes, featuring the oxygen tripodal Kläui ligands [(η⁵-C₅R₅)Co{P(OEt)₂O}₃]^-, {R = H, (L_OEt^-); Me (L*_OEt^-)}, are reported. Reaction of NaL_OEt (1a) and NaL*_OEt (1b) with SnCl₂, yielded the rare four-coordinate L_OEtSnCl (2a) and L*_OEtSnCl (2b) complexes. Accordingly, L_OEtSnPh₃ (3a) and L*_OEtSnPh₃ (3b) were prepared, starting from Ph₃SnCl. Characterization includes spectroscopy and X-ray diffraction studies for 2a, 2b and 3b. The antiplatelet activity of the lead complexes 2b and 3a (IC₅₀ = 0.5 μΜ) is superior compared to that of 1a and 1b, while both complexes display a pronounced inhibitory activity against thrombin (IC₅₀ = 1.8 μM and 0.6 μM). The in vitro cytotoxic activities of 3a and 2b on human Jurkat T lymphoblastic tumor cell line is higher than that of cisplatin.

Enhancement of Photostabilization of Poly(Vinyl Chloride) in the Presence of Tin-Cephalexin Complexes

Poly(vinyl chloride), PVC, has many attractive properties, including low cost of manufacture, resistance to acid and alkali corrosion, and ease of molding. However, PVC suffers from aging in harsh conditions, leading to the shortening of its useful life. Stability to irradiation, for example, can be improved through the incorporation of additives to PVC. The design, synthesis, and application of new stabilizers continue to attract attention. The current work investigates the effect of three tin-cephalexin complexes on the stability of PVC on irradiation with ultraviolet (UV) light (λ = 313 nm) at 25 °C for a long duration. The PVC was blended with tin-cephalexin complexes at low concentrations (0.5% by weight), and thin films (around 40 µm) were made from the mixed materials. Various methods, including weight loss, infrared spectroscopy, and surface inspection of irradiated films were used to investigate the role played by these additives in the inhibition of PVC photodecomposition. The results confirmed that the additives led to a significant reduction in the rate of photodecomposition of the PVC blends. Tin-cephalexin complexes can absorb harmful radiation, deactivate hydrogen chloride, and scavenge high-energy species such as peroxides, therefore acting as stabilizers for PVC.

Synthesis of Methyldopa-Tin Complexes and Their Applicability as Photostabilizers for the Protection of Polyvinyl Chloride against Photolysis

Polyvinyl chloride (PVC) is a ubiquitous thermoplastic that is produced on an enormous industrial scale to meet growing global demand. PVC has many favorable properties and is used in various applications. However, photodecomposition occurs when harsh conditions, such as high temperatures in the presence of oxygen and moisture, are encountered. Thus, PVC is blended with additives to increase its resistance to deterioration caused by exposure to ultraviolet light. In the current research, five methyldopa-tin complexes were synthesized and characterized. The methyldopa-tin complexes were mixed with PVC at a concentration of 0.5% by weight, and thin films were produced. The capability of the complexes to protect PVC from irradiation was shown by a reduction in the formation of small residues containing alcohols, ketones, and alkenes, as well as in weight loss and in the molecular weight of irradiated polymeric blends. In addition, the use of the new additives significantly reduced the roughness factor of the irradiated films. The additives containing aromatic substituents (phenyl rings) were more effective compared to those comprising aliphatic substituents (butyl and methyl groups). Methyldopa-tin complexes have the ability to absorb radiation, coordinate with polymeric chains, and act as radical, peroxide, and hydrogen chloride scavengers.

Synthesis and Application of Levofloxacin–Tin Complexes as New Photostabilizers for Polyvinyl Chloride

Polyvinyl chloride (PVC) is a synthetic polymer with a wide range of applications with impact on our daily life. It can undergo photodegradation with toxic products that are hazardous to both human health and the environment. In addition, photodegradation shortens the useful lifetime of the material. Elongation of the effective lifespan of PVC is, therefore, a salient area of research. Recently, a lot of attention has been directed toward the design, preparation, and usage of new additives that are capable of reducing the photodecomposition of PVC. This work investigates the synthesis of new levofloxacin-tin complexes and their potential exploitation against the photodecomposition of PVC. Several levofloxacin-tin complexes have been synthesized, in high yields, by a simple procedure and characterized. The potential use of the additives as photostabilizers for PVC has been investigated through the determination of weight loss, molecular weight depression, formation of fragments containing carbonyl and alkene groups, and surface morphology of irradiated PVC films. The results show that the new additives are effective in reducing the photodegradation of PVC. The new levofloxacin-tin complexes act as absorbers of ultraviolet light and quenchers of highly reactive species such as free radicals produced during photodegradation. They are more effective photostabilizers compared with organotin complexes previously reported. The complexes containing aromatic substituents were more effective than those counterparts having aliphatic residues.

Triphenyltin(IV) dithiocarbamate compound induces genotoxicity and cytotoxicity in K562 human erythroleukemia cells primarily via mitochondria-mediated apoptosis

The novel di-and triphenyltin(IV) dithiocarbamate compounds represented as R_nSnL₂ (where R = C₄H₉, C₆H₅; n = 2,3; L = N,N-dithiocarbamate), Ph₂Sn(N,N-diisopropyldithiocarbamate) (OC1), Ph₃Sn(N,N-diisopropyldithiocarbamate) (OC2), Ph₂Sn(N,N-diallyldithiocarbamate) (OC3), Ph₃Sn(N,N-diallyldithiocarbamate) (OC4), and Ph₂Sn(N,N-diethyldithiocarbamate) (OC5) were assessed for their cytotoxicity in K562 human erythroleukemia cells. All compounds inhibited the growth of cells at low micromolar concentrations (<10 μM), and the mechanism underlying their antiproliferative effects on K562 cells was apoptosis, as corroborated by the exposure of plasma membrane phosphatidylserine. OC2, which showed the most promising antiproliferative activity, was selected for further analyses. The results demonstrated that OC2 induced apoptosis in K562 cells via an intrinsic mitochondrial pathway triggered upon DNA damage, an early apoptotic signal. Subsequently, OC2 produced excessive intracellular reactive oxygen species. The role of oxidative stress was corroborated by the significant reduction in GSH levels and percentage of apoptosis in NAC-pretreated cells. OC2 could arrest the cell cycle progression in the S phase. These new findings elucidate the antiproliferative potential of OC2 in the K562 human erythroleukemia cells and warrant further investigation, specifically to determine the exact signaling pathway underlying its antileukemic efficacy.

Synthesis, computational and biological studies of alkyltin(IV) N-methyl-N-hydroxyethyl dithiocarbamate complexes

Methyltin(IV) of butyltin(IV)-N-hydroxyethyl dithiocarbamate complexes, represented as [(CH3)2Sn(L(OH))2] and [(C4H9)2Sn(L(OH))2] respectively were synthesized and characterized using spectroscopic techniques (1H, 13C and 119Sn NMR) and elemental analysis. Both infrared and NMR data showed that, the complexes were formed via two sulphur atoms of the dithiocarbamate group. This mode of coordination was further supported by the DFT calculation, which suggested the formation of a distorted octahedral geometry around the tin atom. The complexes were screened for their antioxidant, cytotoxicity and anti-inflammatory properties. Four different assays including DPPH, nitric oxide, reducing power and hydrogen peroxides were used for the antioxidant studies, while an in vitro anti-inflammatory study was done using albumin denaturation assay. The complexes showed good antioxidant activity, especially in the DPPH assay. Butyltin(IV)-N-hydroxyethyl dithiocarbamate showed better cytotoxicity activity compared to methyltin(IV)-N-hydroxyethyl dithiocarbamate in the selected cell lines, which included KMST-6, Caco-2 and A549 cell lines. The anti-inflammatory activities revealed that the two complexes have useful activities better than diclofenac used as control drug.

Cellular Basis of Organotin(IV) Derivatives as Anticancer Metallodrugs: A Review

Organotin(IV) compounds have wide applications in industrial and agricultural fields owing to their ability to act as poly(vinyl chloride) stabilizers and catalytic agents as well as their medicinal properties. Moreover, organotin(IV) compounds may have applications as antitumor, anti-inflammatory, antifungal, or antimicrobial agents based on the observation of synergistic effects following the binding of their respective ligands, resulting in the enhancement of their biological activities. In this review, we describe the antiproliferative activities of organotin(IV) compounds in various human cancer cell lines based on different types of ligands. We also discuss the molecular mechanisms through which organotin(IV) compounds induce cell death via apoptosis through the mitochondrial intrinsic pathway. Finally, we present the mechanisms of cell cycle arrest induced by organotin(IV) compounds. Our report provides a basis for studies of the antitumor activities of organotin(IV) compounds and highlights the potential applications of these compounds as anticancer metallodrugs with low toxicity and few side effects.

Biobased polyurethanes for biomedical applications

Polyurethanes (PUs) are a major family of polymers displaying a wide spectrum of physico-chemical, mechanical and structural properties for a large range of fields. They have shown suitable for biomedical applications and are used in this domain since decades. The current variety of biomass available has extended the diversity of starting materials for the elaboration of new biobased macromolecular architectures, allowing the development of biobased PUs with advanced properties such as controlled biotic and abiotic degradation. In this frame, new tunable biomedical devices have been successfully designed. PU structures with precise tissue biomimicking can be obtained and are adequate for adhesion, proliferation and differentiation of many cell's types. Moreover, new smart shape-memory PUs with adjustable shape-recovery properties have demonstrated promising results for biomedical applications such as wound healing. The fossil-based starting materials substitution for biomedical implants is slowly improving, nonetheless better renewable contents need to be achieved for most PUs to obtain biobased certifications. After a presentation of some PU generalities and an understanding of a biomaterial structure-biocompatibility relationship, recent developments of biobased PUs for non-implantable devices as well as short- and long-term implants are described in detail in this review and compared to more conventional PU structures.

Conformational analysis of two new organotin(IV) structures completed with a CSD survey

The conformational flexibilities are studied in two new organotin(IV) complexes, namely, trans-dichloridodimethylbis[N,N',N''-tris(2-chlorobenzyl)phosphoric triamide]tin(IV), [Sn(CH₃)₂(C₂₁H₂₁Cl₃N₃OP)₂Cl₂] or Sn(CH₃)₂Cl₂{OP[NHCH₂C₆H₄(2-Cl)]₃}₂, (I), and bis(dipropylammonium) tetrachloridodimethylstannate(IV), [(CH₃CH₂CH₂)₂NH₂]₂[Sn(CH₃)₂Cl₄], (II), and their analogous structures from the Cambridge Structural Database (CSD). The conformations are considered based on the N-P=O-Sn torsion angles for (I) and the C-C-C-N, C-C-N-C, C-N-C-C and N-C-C-C torsion angles for the two symmetry-independent [CH₃CH₂CH₂NH₂CH₂CH₂CH₃]⁺ cations in (II), and the ±ac±sp±ac (ac = anticlinal and sp = synperiplanar) and ±ap±ap±ap±ap (ap = antiperiplanar) conformations are observed, respectively. In both structures, the four atoms in the corners of the square-planar segment of the octahedral shape around the Sn atom participate in normal hydrogen-bonding interactions as acceptors, which include two O and two Cl atoms for (I), and four Cl atoms for (II). However, the phosphoric triamide ligands block the environment around the Sn atom and limit the hydrogen-bond pattern to form a supramolecular ribbon assembly, while in the presence of small organic cations in (II), a two-dimensional hydrogen-bonded architecture is achieved. The weak interactions π-π, C-H...π and C-Cl...π in (I), and C-H...Cl in (II) do not change the dimensionality of the hydrogen-bond pattern. The 62 CSD structures analogous to (I), i.e. with an SnOPN₃ segment (including 83 entries) fall into four categories of conformations based on the N-P=O-Sn torsion angles. The 132 [(CH₃CH₂CH₂)₂NH₂]⁺ cations from 85 CSD structures are classified into seven groups based on the torsion angles noted for (II). Most of the CSD structures adopt the same associated conformations noted for (I) and (II). 15 [Sn(CH₃)₂Cl₄]^2- anions extracted from the CSD are compared with the structure of (II).

Synthesis, structural characterization and in vitro antiproliferative effects of novel organotin(iv) compounds with nicotinate and isonicotinate moieties on carcinoma cells

Novel triorganotin(iv) nicotinates and isonicotinates were successfully synthesized and fully characterized. The preliminary results for their in vitro antiproliferative activity against the mouse colon carcinoma C26 cell line are also reported.

A Prelude to Biogermylene Chemistry*

The biological applications of germylenes remain unrealised owing to their unstable nature. We report the isolation of air-, water-, and culture-medium-stable germylene DPMGeOH (3; DPM=dipyrromethene ligand) and its potential biological application. Compound 3 exhibits antiproliferative effects comparable to that of cisplatin in human cancer cells. The cytotoxicity of compound 3 on normal epithelial cells is minimal and is similar to that of the currently used anticancer drugs. These findings provide a framework for a plethora of biological studies using germylenes and have important implications for low-valent main-group chemistry.

Organotin compound DBDCT induces CYP3A suppression through NF-κB-mediated repression of PXR activity

Organotin anticancer agent di-n-butyl-di-(4-chlorobenzohydroxamato)tin(iv) (DBDCT) exerted an inhibitory effect on its major metabolic enzyme cytochrome CYP3A. But whether hepatic drug-metabolizing enzymes and their regulatory nuclear receptors including pregnane PXR and constitutive androstane CAR binding with retinoid receptor RXR as a heterodimer are involved in the DBDCT-mediated regulation of CYP3A remains unclear. This study was undertaken to determine the mechanisms responsible for the effects of DBDCT on CYP3A suppression, focusing on the PXR-mediated and NF-κB pathways. The results indicated DBDCT suppressed CYP3A expression by inhibiting CAR expression. But what's interesting is, both protein and mRNA of PXR increased with increasing DBDCT. A further exploration, dual luciferase reporter gene analysis, clarified that DBDCT induced CYP3A expression elevation via the PXR-mediated pathway and this induction was countered by activation of NF-κB, which played a pivotal role in suppression of CYP3A through disrupting the association of the PXR-RXRα complex with DNA sequences by EMSA. PXR-mediated CYP3A expression was similarly demonstrated by RNAi. As expected, expression of CYP3A and its mRNA levels were reduced by DBDCT only in NF-κB(+/+) but not in NF-κB(-/-) cells. The inductive effect of DBDCT on CYP3A4 mRNA was enhanced in PXR shRNA-transfected cells but weakened in the ip65 group, which showed both PXR up-regulated CYP3A expression and NF-κB p65 activation directly contributed to CYP3A inhibition. In conclusion, activated NF-κB by DBDCT interacts directly with the DNA-binding domain of PXR, and disrupts the binding between the PXR-RXR dimer, thereby affecting the regulatory process for CYP3A transcription and, therefore, leading to a decrease of the expression of the PXR-regulated CYP3A.

Novel selective anticancer agents based on Sn and Au complexes. Mini-review

Cancer is one of the most common causes of death in modern medicine. Molecular design of novel substances with pharmacological activity is one of the goals of medicinal inorganic chemistry. Platinum complexes are widely used in the treatment of cancer, despite high efficacy their use is limited by side effects, as well as primary or acquired resistance. In this regard, the search for novel metal-containing antitumor compounds is underway. Organotins and gold compounds are promising pharmacological agents with anti-cancer properties. The introduction of protective antioxidant fragments into inorganic compounds molecules is a way to reduce the side effects of anti-cancer drugs on healthy cells. 2,6-dialkylphenols belonging to vitamin E (α-tocopherol) mimetics are widely used as antioxidants and stabilizers. The properties of Ph3SnCl (Sn-I), Ph3PAuCl (Au-I) and complexes Ph3SnSR (Sn-II) and Ph3PAuSR (Au-II) based on 2,6-di-tert-butyl-4-mercaptophenol (RSH) as radical scavengers and reducing agents were studied in model reactions. For Sn-II and Au-II the comparative study of cytotoxic action was made and the IC50 values on different cancer cell lines were found to be depended on the nature of metal. In general, Sn(IV) complexes possessed higher cytotoxicity than Au(I) complexes. In order to clarify the mechanism of cytotoxic mode of action the effect of compounds on Fe3+-induced lipid peroxidation, mitochondrial potential and mitochondrial permeability, cell cycle and induction of apoptosis was studied. Organotin compounds can bind tubulin SH-groups and inhibit its polymerization by a dose-dependent mechanism, whereas gold compounds inhibit Thioredoxin reductase (TrxR). In vivo experiments on acute toxicity of Sn-II and Au-II proved their moderate toxic action that opens prospects for the further study as antitumor agents.

Triplet Tellurophene-Based Semiconducting Polymer Nanoparticles for Near-Infrared-Mediated Cancer Theranostics

Semiconducting polymer (SP) nanoparticles (NPs) have recently emerged as one of the most promising agents for photoacoustic imaging (PAI)-guided photothermal/photodynamic therapy (PTT/PDT). Herein, a triplet tellurophene-based SP (PNDI-2T) was synthesized with efficient tin-free direct heteroarylation polycondensation. The PNDI-2T NPs display remarkable near-infrared absorption and low cytotoxicity. In addition, PNDI-2T NPs can generate abundant reactive oxygen species (ROS) since tellurophene facilitates the intersystem crossing to generate triplet excited states. Remarkably, PNDI-2T NPs present a high photothermal conversion efficiency (η = 45%) and a high ROS yield (ΦΔ = 38.7%) under 808 nm laser irradiation. Furthermore, we showed that PNDI-2T NPs could be excellent PAI-guided PTT/PDT agents for cancer theranostics. This study provides a new route to developing highly efficient and low cytotoxic agents for PAI-guided PTT/PDT.

Organotin(IV) Dithiocarbamate Complexes: Chemistry and Biological Activity

Significant attention has been given to organotin(IV) dithiocabamate compounds in recent times. This is due to their ability to stabilize specific stereochemistry in their complexes, and their diverse application in agriculture, biology, catalysis and as single source precursors for tin sulfide nanoparticles. These complexes have good coordination chemistry, stability and diverse molecular structures which, thus, prompt their wide range of biological activities. Their unique stereo-electronic properties underline their relevance in the area of medicinal chemistry. Organotin(IV) dithiocabamate compounds owe their functionalities and usefulness to the individual properties of the organotin(IV) and the dithiocarbamate moieties present within the molecule. These individual properties create a synergy of action in the hybrid complex, prompting an enhanced biological activity. In this review, we discuss the chemistry of organotin(IV) dithiocarbamate complexes that accounts for their relevance in biology and medicine.

Triphenylstannyl((arylimino)methyl)benzoates with selective potency that induce G1 and G2/M cell cycle arrest and trigger apoptosis via ROS in human cervical cancer cells

Metal complexes with organelle specificity and potent but selective cytotoxicity are highly desirable. A novel series of triphenylstannyl 4-((arylimino)methyl)benzoates (2-8) were obtained by the reactions of triphenylstannyl 4-formylbenzoate [Ph₃Sn(L¹)] 1 with primary aromatic amines. Two representative compounds (10, 11) were also synthesized by reacting aqua-triphenylstannyl 2-formylbenzoate [Ph₃Sn(L⁹)(H₂O)] (9) with aniline and p-fluoroaniline, respectively. These compounds were characterized by elemental analysis, IR and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy, as well as single-crystal X-ray diffraction for compounds 5, 7-11 and three pro-ligands. The in vitro cytotoxic activities of 1-11 were assessed using the MTT tetrazolium dye assay against HeLa (human cervical) and MDA-MB-231 (breast) cancer cells, with IC₅₀ values revealing high activity. Compared to cisplatin, compounds 1-11 exhibited enhanced cytotoxic efficacy, indicating their potential as potent anticancer agents. Among these, 1 and 5 demonstrated maximum inhibition in HeLa cells, with negligible effect on normal human embryonic kidney (HEK) cells. The combined results of the DCFH-DA dye and Hoechst 33342/PI nuclear staining assays, along with flow cytometry analysis, show that they possess a dual mode of action: They induced apoptotic cell death, attributable to the tin-assisted generation of reactive oxygen species. Cell cycle analyses indicated that compounds 1 and 5 exhibit cell growth inhibition and may cause turbulences in the G1 and G2/M phases.

Triphenyltin(IV) benzoates with diazenyl/imino scaffold exhibiting remarkable apoptosis mediated by reactive oxygen species

The cytotoxic potency of a series of triphenyltin(IV) compounds of general composition [Ph₃Sn(Lⁿ)] (1-6) has been probed in vitro employing MDA-MB-231 (human breast cancer) and HeLa (human cervical cancer) cell lines, where Lⁿ=L^1-3; isomeric 2/3/4-{(E)-2-[4-(dimethylamino)phenyl]diazenyl}benzoates and L^4-6 are their corresponding isoelectronic imino analogues 2/3/4-[(E)-{[4-(dimethylamino)phenyl]methylidene}amino]benzoates. Compounds 1-6 have been characterized by elemental analysis and their spectroscopic properties were studied using IR and NMR (¹H, ¹³C, ¹¹⁹Sn) techniques. The molecular structures of a pro-ligand 2-[(E)-{[4-(dimethylamino)phenyl]methylidene}amino]benzoic acid (HL⁴) and two representative molecules, Ph₃Sn(L²) 2 and Ph₃Sn(L⁵) 5, have been determined by X-ray crystallography. Structural analyses of 2 and 5 revealed distorted tetrahedral geometries within C₃O donor sets owing to monodentate modes of coordination of the respective carboxylate ligands, close intramolecular Sn…O(carbonyl) interactions notwithstanding. Cytotoxic studies in vitro in MDA-MB-231 and HeLa cell lines revealed high activity, in sub-micromolar range, for all investigated compounds. Among these, 1 and 3 exhibited potent cytotoxicity most effectively towards MDA-MB-231 cells with a IC₅₀ value of 1.19 and 1.44μM, respectively, whereas 5 showed remarkable activity towards HeLa cells with a IC₅₀ value of 0.88μM, yet the series of compounds had minimal cytotoxic effect on normal HEK 293 (human embryonic kidney) cell line. The underlying investigation suggested that the compounds exert potent antitumor effect by elevating intracellular reactive oxygen species generation and cause delay in cell cycle by inhibiting cells at G₂/M phase. The results presented herein suggest further development of this class of triphenyltin(IV) compounds-based drugs as potential anti-cancer therapies should be pursued.

Hepatotoxicity and proteomic mechanism of Di-n-butyl-di-(4-chlorobenzohydroxamato)tin(IV) (DBDCT) in vivo

Di-n-butyl-di-(4-chlorobenzohydroxamato)tin(IV) (DBDCT) is an anti-tumour organotin(IV) compound with hepatotoxicity. To investigate the hepatotoxicity and mechanisms of DBDCT in vivo, proteomic technology 2D gel combined with MALDI-TOF-MS was used in our research. Results indicated that DBDCT increased AST, AKP and ACP activities and decreased ALT activity. Further, sporadic eosinophilic changes and nuclear pyknosis were visible in hepatic pathological observation. Proteomic analysis showed that twenty-two proteins involved in amino acid, nucleic acid, carbohydrate and lipid metabolism, stress response, multicellular organism development and cell apoptosis were differentially expressed and identified. Notably, a considerable amount of the altered proteins, such as OAT, HPPD, M2GD, GSTM2, Glud1, GSTa, HS90β and PDIA3 participated in multi-metabolic pathways and oxidative stress reactions. Our findings indicated that the inhibition of enzyme activity and oxidative stress were the major mechanisms by which DBDCT induced hepatotoxicity, and the altered proteins could be potential drug targets for the further design of new type of organic tin with high activity and low toxicology.

Synthesis, photophysical properties and structures of organotin-Schiff bases utilizing aromatic amino acid from the chiral pool and evaluation of the biological perspective of a triphenyltin compound

Five new organotin(IV) complexes of compositions [Me₂SnL¹] (1), [Me₂SnL²]_n (2), [Me₂SnL³] (3), [Ph₃SnL¹H]_n (4) and [Ph₃SnL³H] (5) (where L¹=(2S)-2-((E)-((Z)-4-hydroxypent-3-en-2-ylidene)amino)-3-(1H-indol-3-yl)propanoate, L²=(2S)-(E)-2-((2-hydroxybenzylidene)amino)-3-(1H-indol-3-yl)propanoate and L³=(2S)-(E)-2-((1-(2-hydroxyphenyl)ethylidene)amino)-3-(1H-indol-3-yl)propanoate were synthesized and spectroscopically characterized. The crystal structures of 1-4 were determined. For the dimethyltin derivative 2, a polymeric chain structure was observed as a result of a long Sn∙∙∙O contact involving the exocyclic carbonyl oxygen-atom from the tridentate ligand of a neighboring Sn-complex unit. The tin atom in this complex has a distorted octahedral coordination geometry, in which the long Sn-O bond is almost trans to the tridentate ligand nitrogen-atom. In contrast, the dimethyltin(IV) complexes 1 and 3 displayed discrete monomeric structures where the tin atom has distorted trigonal-bipyramidal geometry with the two coordinating L oxygen atoms defining the axial positions. On the other hand, 4 is a chain polymer in the solid state. The ligand-bridged Sn atoms adopt a trans-Ph₃SnO₂ trigonal-bipyramidal configuration with equatorial phenyl groups. A carboxylato oxygen atom from one and the hydroxyl oxygen of the successive ligand in the chain occupy the axial positions. The solution structures were predicted by the use of ¹¹⁹Sn NMR chemical shifts. The photophysical properties of the complexes were investigated in the solid and in solution. The triphenyltin(IV) compound 4 was tested in detail ex vivo against A375 (human melanoma) cell line, exhibiting an IC₅₀ value of 261nM to induce cell death as assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay without significant alteration of cytolysis as determined by lactate dehydrogenase (LDH) assay. Compound 4-mediated potent cell death was also determined by Live and Dead assay and caspase-mediated cleavage of poly-ADP ribose polymerase (PARP). Potent cell death activity was not observed in primary cells, like blood-derived peripheral mononuclear cells (PBMC). Compound 4 inhibited the diphenyl hexatriene (DPH) binding to cells and decreased the micro viscosity in a dose-dependent manner. Additionally, the ability of 4 and cyclodextrin (CD) to interact was determined by molecular modelling.