Novel triphenyltin(IV) compounds with carboxylato N-functionalized 2-quinolones as promising potential anticancer drug candidates: in vitro and in vivo evaluation

Three newly synthesized triphenyltin(IV) compounds, Ph3SnL1 (L1- = 3-(4-methyl-2-oxoquinolin-1(2H)-yl)propanoato), Ph3SnL2 (L2- = 2-(4-methyl-2-oxoquinolin-1(2H)-yl)ethanoato), and Ph3SnL3 (L3- = 2-(4-hydroxy-2-oxoquinolin-1(2H)-yl)ethanoato), were characterized by elemental microanalysis, FT-IR spectroscopy and multinuclear (1H, 13C and 119Sn) NMR spectroscopy. A single X-ray diffraction study indicates that compounds Ph3SnL1 and Ph3SnL2 exhibit a 1D zig-zag chain polymeric structure, which in the case of Ph3SnL2 is additionally stabilized by π-interactions. In addition, the synthesized compounds were further examined using density functional theory and natural bond orbital analysis. The compounds have been evaluated for their in vitro anticancer activity against three human cell lines: MCF-7 (breast adenocarcinoma), A375 (melanoma), HCT116 (colorectal carcinoma), and three murine cell lines: 4T1 (breast carcinoma), B16 (melanoma), CT26 (colon carcinoma) using MTT and CV assays. The IC50 values fall in the nanomolar range, indicating that these compounds possess better anticancer activity than cisplatin. The study of the effect of the newly developed drug Ph3SnL1 showed its plasticity in achieving an antitumor effect in vitro, which depends on the specificity of the phenotype and the redox status of the malignant cell line and ranges from the initiation of apoptotic cell death to the induction of differentiation to a more mature cell form. In the syngeneic model of murine melanoma, Ph3SnL1 showed the potential to reduce the tumor volume similar to cisplatin, but in a well-tolerated form and with low systemic toxicity, representing a significant advantage over the conventional drug.

Synthesis, Characterization, Biological Activity and Molecular Docking Studies of Novel Organotin(IV) Carboxylates

Four new carboxylates complexes with general formula R₂SnL₂ and R₃SnL, where R = n-butyl (1, 3), methyl (2, 4) and L = 4-Chlorophenoxyacetate, were synthesized in significant yields. FT-IR analysis revealed a chelating (1 and 2) and a bridging bidentate (3 and 4) coordination modes for the carboxylate ligand in solid state which was further confirmed by the single crystal X-ray analysis of complex 4. The NMR data (¹H, ¹³C and ¹¹⁹Sn) revealed a higher coordination number around the tin center in R₂SnL₂ (1 and 2) compared to R₃SnL (3 and 4). A close matching was observed between the experimental and calculated structures (obtained at B3LYP/6-31G* + LANL2DZ basis set). Quantum chemical analysis indicates that the carboxylate moiety has the major contribution in the formation of filled and unfilled orbitals as well as in ligand to ligand intramolecular charge transfer during the electronic transitions. The cytotoxicity data of the screened compounds evaluated against lung cancer cell line (A549) and normal lung fibroblast cell line (MRC-5) revealed that 1, 3 and 4 have shown dose dependent cytotoxic effects while HL and 2 have shown steady and low cytotoxic activities. The antibacterial activity of complexes 1–4 is higher than that of HL. Molecular docking study showed an intercalation binding mode for complex 3 with DNA (docking score = −3.6005) involving four polar interactions. Complex 3 docking with tubulin (PDB ID 1SA0) with colchicine as a target protein resulted in three polar interactions (docking score −5.2957). Further, the docking analysis of the HL and 1–4 has shown an adequate interactions with the coronavirus SARS-CoV-2 spike protein, nucleocapsid protein and human angiotensin converting enzyme (ACE2).

In Vitro Evaluation of Antiproliferative Properties of Novel Organotin(IV) Carboxylate Compounds with Propanoic Acid Derivatives on a Panel of Human Cancer Cell Lines

The synthesis of novel triphenyltin(IV) compounds, Ph3SnLn (n = 1-3), with oxaprozin (3-(4,5-diphenyloxazol-2-yl)propanoic acid), HL1, and the new propanoic acid derivatives 3-(4,5-bis(4-methoxylphenyl)oxazol-2-yl)propanoic acid, HL2, and 3-(2,5-dioxo-4,4-diphenylimidazolidin-1-yl)propanoic acid, HL3, has been performed. The ligands represent commercial drugs or their derivatives and the tin complexes have been characterized by standard analytical methods. The in vitro antiproliferative activity of both ligands and organotin(IV) compounds has been evaluated on the following tumour cell lines: human prostate cancer (PC-3), human colorectal adenocarcinoma (HT-29), breast cancer (MCF-7), and hepatocellular cancer (HepG2), as well as on normal mouse embryonic fibroblast cells (NIH3T3) with the aid of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-12 diphenyltetrazolium bromide) and CV (crystal violet) assays. Contrary to the inactive ligand precursors, all organotin(IV) carboxylates showed very good activity with IC50 values ranging from 0.100 to 0.758 µM. According to the CV assay (IC50 = 0.218 ± 0.025 µM), complex Ph3SnL1 demonstrated the highest cytotoxicity against the caspase 3 deficient MCF-7 cell line. Inductively coupled plasma mass spectrometry (ICP-MS) analysis indicated a two-fold lower concentration of tin in MCF-7 cells in comparison to platinum. To investigate the mechanism of action of the compound Ph3SnL1 on MCF-7 cells, morphological, autophagy and cell cycle analysis, as well as the activation of caspase and ROS/RNS and NO production, has been performed. Results suggest that Ph3SnL1 induces caspase-independent apoptosis in MCF-7 cells.

The different modes of chiral [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines: crystal packing, conformation investigation and cellular activity

The crystal structures of four new chiral [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines are described, namely, ethyl 5'-benzoyl-5'H,7'H-spiro[cyclohexane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₁₉H₂₂N₄O₃S, ethyl 5'-(4-methoxybenzoyl)-5'H,7'H-spiro[cyclohexane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₂₀H₂₄N₄O₄S, ethyl 6,6-dimethyl-5-(4-methylbenzoyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C₁₇H₂₀N₄O₃S, and ethyl 5-benzoyl-6-(4-methoxyphenyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C₂₁H₂₀N₄O₄S. The crystallographic data and cell activities of these four compounds and of the structures of three previously reported similar compounds, namely, ethyl 5'-(4-methylbenzoyl)-5'H,7'H-spiro[cyclopentane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₁₉H₂₂N₄O₃S, ethyl 5'-(4-methoxybenzoyl)-5'H,7'H-spiro[cyclopentane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate, C₁₉H₂₂N₄O₄S, and ethyl 6-methyl-5-(4-methylbenzoyl)-6-phenyl-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine-3-carboxylate, C₂₂H₂₂N₄O₃S, are contrasted and compared. For both crystallization and an MTT assay, racemic mixtures of the corresponding [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines were used. The main manner of molecular packing in these compounds is the organization of either enantiomeric pairs or dimers. In both cases, the formation of two three-centre hydrogen bonds can be detected resulting from intramolecular N-H...O and intermolecular N-H...O or N-H...N interactions. Molecules of different enantiomeric forms can also form chains through N-H...O hydrogen bonds or form layers between which only weak hydrophobic contacts exist. Unlike other [1,2,3]triazolo[5,1-b][1,3,4]thiadiazines, ethyl 5'-benzoyl-5'H,7'H-spiro[cyclohexane-1,6'-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine]-3'-carboxylate contains molecules of only the (R)-enantiomer; moreover, the N-H group does not participate in any significant intermolecular interactions. Molecular mechanics methods (force field OPLS3e) and the DFT B3LYP/6-31G+(d,p) method show that the compound forming enantiomeric pairs via weak N-H...N hydrogen bonds is subject to greater distortion of the geometry under the influence of the intermolecular interactions in the crystal. For intramolecular N-H...O and S...O interactions, an analysis of the noncovalent interactions (NCIs) was carried out. The cellular activities of the compounds were tested by evaluating their antiproliferative effect against two normal human cell lines and two cancer cell lines in terms of half-maximum inhibitory concentration (IC₅₀). Some derivatives have been found to be very effective in inhibiting the growth of Hela cells at nanomolar and submicromolar concentrations with minimal cytotoxicity in relation to normal cells.

Molecular docking, quantum chemical computational and vibrational studies on bicyclic heterocycle "6-nitro-2,3-dihydro-1,4-benzodioxine": Anti-cancer agent

The heterocyclic aromatic compounds are primarily used to make pharmaceutical and agrochemicals. In addition, these compounds can be chosen as antioxidants, corrosion inhibitors, electro and opto-electronic devices, polymer material, dye stuff, developers, etc. On the account of this, the heterocyclic aromatic 6-nitro-2,3-dihydro-1,4-benzodioxine (6N3DB) was chosen and the structure is optimized to predict the important properties of it. The structural parameters such as bond length and bond angle have been obtained by DFT/B3LYP/6-311++G(d,p) basis set to know the geometry and orientation of 6N3DB. The molecule has been characterized by FT-IR and FT-Raman spectroscopic techniques to predict the functional groups, vibrational modes and aromatic nature of 6N3DB. The chemical shifts of ¹H and ¹³C have been obtained experimentally and compared with the theoretical data. The parameters such as the band gap between HOMO-LUMO orbitals, λ_max, and electron transition probability in frontier orbitals have been estimated to know the NLO and corrosion inhibition activity. HOMO-LUMO orbital diagram has been obtained for different energy levels and their band gap energies have been compared with UV-vis band gap values. The chemical significance of the molecule has been explained using ELF, LOL, and RDG. The binding energy and intermolecular energy values indicate that the title compound possesses anti-cancer property through hydrolase inhibition activity.

Photostabilization of Poly(vinyl chloride) by Organotin(IV) Compounds against Photodegradation

Poly(vinyl chloride) (PVC), a polymer widely used in common household and industrial materials, undergoes photodegradation upon ultraviolet irradiation, leading to undesirable physicochemical properties and a reduced lifetime. In this study, four telmisartan organotin(IV) compounds were tested as photostabilizers against photodegradation. PVC films (40-µm thickness) containing these compounds (0.5 wt%) were irradiated with ultraviolet light at room temperature for up to 300 h. Changes in various polymeric parameters, including the growth of hydroxyl, carbonyl, and alkene functional groups, weight loss, reduction in molecular weight, and appearance of surface irregularities, were investigated to test the efficiency of the photostabilizers. The changes were more noticeable in the blank PVC film than in the films containing the telmisartan organotin(IV) compounds. These results reflect that these compounds effectively inhibit the photodegradation of PVC, possibly by acting as hydrogen chloride and radical scavengers, peroxide decomposers, and primary photostabilizers. The synthesized organotin(IV) complexes could be used as PVC additives to enhance photostability.