Antifungal activity of organotin compounds with functionalized carboxylates evaluated by the microdilution bioassayin vitro

Deciphering mechanistic implications of antimicrobial and antioxidant potentials of certain new dibutyltin(IV) formulations as possible therapeutic options based on DFT and hybrid materials paradigm

Mechanistic implications of antimicrobial and in vitro antioxidant potentials of a set of newly generated nonbridged mononuclear N,O-orthometallated and carboxylate bridged binuclear nonorthometallated dibutyltin(IV) formulations have been investigated. Some of these formulations were screened for their antibacterial and antifungal activities against Escherichia coli and Candida albicans, respectively whereas in vitro antioxidant potential was examined by Ferric reducing antioxidant power (FRAP) assay. Nonbridged mononuclear N,O-orthometallated dibutyltin(IV) formulations were generated by the reactions of Bu₂ SnCl₂ with sodium salts of 2-aminophenol/substituted 2-aminophenol and flexible N-protected amino acids in 1:1:1 molar ratio in refluxing dry THF. Plausible structures of these nonbridged mononuclear N,O-orthometallated dibutyltin(IV) formulations containing flexible N-protected amino acids have been suggested on the basis of spectroscopic and mass studies of some representative formulations. Plausible structures suggested on the basis of spectroscopic studies are corroborated by density functional theory (DFT/B3LYP method) (SPARTAN-20) investigation of a representative dibutyltin(IV) complex and the ligands involved in it. The presence of two different classes of organic ligands in this complex provides an opportunity to study optimized topologies, bonding, distortions, optimized energy, and stability of the complex.

Synthesis, spectroscopy, and density functional theory of organotin and organosilicon complexes of bioactive ligands containing nitrogen, sulfur donor atoms as antimicrobial agents: in vitro and in silico studies

Recently inorganic-based metallodrugs provide an effective mechanism for the drugs on the choice of metal and its properties. Medicinal complex compounds provide an efficient platform for various pharmacological and therapeutic applications. Six new organotin and organosilicon complexes containing sulphur and nitrogen donor atoms were synthesised. These complexes of (E)-2-((4-methoxybenzylidene)amino)benzenethiol were characterized by elemental analyses, molecular weights, conductance measurements, infrared, electronic, and NMR spectroscopy. The data analysis indicated that the Schiff base contains bidentate nitrogen sulfur (NS) domains and was coordinated to silicon (Si) and tin (Sn) moieties via the imine-N and thiolic-S atoms, resulting in penta- and hexa-coordinated complexes in 1 : 1 and 1 : 2 ratios, respectively. The geometries around the Sn and Si atoms in complexes 1, 3, and 5 were five-coordinated and 2, 4, and 6 were six-coordinated octahedra, respectively. Density functional theory (DFT) was used to determine the optimal structural parameters. The antimicrobial activities of the ligand and its complexes were determined. These data indicate that metal complexes are more effective against bacteria and fungi in comparison to the free ligand. Molecular docking was performed to interpret the interaction of protein and various complexes and it was observed that compound 6 showed the highest binding affinity.

Anti-biofilm activity of a novel pit and fissure self-adhesive sealant modified with metallic monomers

Dental plaque is a biofilm composed of a complex oral microbial community. The accumulation of plaque in the pit and fissures of dental elements often leads to the development of tooth decay (dental caries). Here, potent anti-biofilm materials were developed by incorporating zinc methacrylates or di-n-butyl-dimethacrylate-tin into the light-curable sealant and their physical, mechanical, and biological properties were evaluated. The data revealed that 5% di-n-butyl-dimethacrylate-tin (SnM 5%) incorporated sealant showed strong anti-biofilm efficacy against various single-species (Streptococcus mutans or Streptococcus oralis or Candida albicans) and S. mutans-C. albicans cross-kingdom dual-species biofilms without either impairing the mechanical properties of the sealant or causing cytotoxicities against mouse fibroblasts. The findings indicate that the incorporation of SnM 5% in the experimental pit and fissure self-adhesive sealant may have the potential to be part of current chemotherapeutic strategies to prevent the formation of cariogenic oral biofilms that cause dental caries.

Identification of the Potential Biological Preservative Tetramycin A-Producing Strain and Enhancing Its Production

The aim of this study was to develop a potential microbial preservative to prevent the growth of fungi in food. The isolate ZC-G-5 showed strong antifungal activity against food spoilage fungi and Streptomyces albulus was identified on the basis of morphologic, culture, and 16S rDNA sequence analyses. The active metabolite was elucidated as tetramycin A (TMA) through spectroscopic techniques, including HR-ESI-MS, 1D-NMR, and 2D-NMR. An antifungal activity assay revealed that the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of TMA were 1.50-2.50 and 3.00-5.00 μg/ml, respectively. In situ antifungal activity analyses demonstrated that 90.0 μg/ml of TMA could inhibit the growth of fungi for over 14 days. In order to enhance TMA production, the high-yield mutant strain YB101 was screened, based on the isolate ZC-G-5, using a high-throughput screening method. The best metabolic precursor was selected during fermentation, when the concentration of glycerol was 8% (v/v) in Gauze's broth medium to cultivate the mutant strain YB101; the concentration of TMA could be increased to 960.0 μg/ml, compared with the original isolate ZC-G-5, where the concentration of the TMA was only 225.0 μg/ml. Our study may contribute to the application of S. albulus and its active metabolite as a potential bio-preservative in the food industry.

New cytotoxic butyltin complexes with 2-sulfobenzoic acid: Molecular interaction with lipid bilayers and DNA as well as in vitro anticancer activity

New butyltin complexes with 2-sulfobenzoic acid: [Sn(C4H9)2{O3SC6H4COO-2}(H2O)]·(C2H5OH) (DBTsbz), [Sn(C4H9)3{O3SC6H4COOH-2}] (TBTsbz) and [Sn2(C4H9)6{μ-O3SC6H4COO-2}] (DTBTsbz) are very effective cytotoxic agents against tumor cells. The molecular interaction of these complexes with lipid membranes and DNA has been investigated. The IR spectra and changes of (1)H, (13)C chemical shifts suggest that SO3 and COO groups of 2-sulfobenzoato ligand interact with O atom of glycerin fragment of DPPC. Moreover, the compounds form Sn-OP bonds with phosphate groups of DPPC, which was shown by the lower frequency shift of the νs(PO2(-)) and νas(PO2(-)) band, by change of (31)P NMR signals and by DFT calculation. Another possibility is the interaction of the phosphate group of DPPC owing to formation of hydrogen bond O-H…O-P between water molecule coordinated to Sn and oxygen atom from the phosphate group. Using TCSPC-FCS we characterized DNA supramolecular assemblies' formation upon increasing TBTsbz, DTBTsbz and DBTsbz concentration. Diffusion time, lifetime and particle number changes are altered systematically with increasing Ccomp/CDNAbp ratio in following effectiveness order DBTsbz > TBTsbz > DTBTsbz. From those parameters we can conclude that all these compounds lead to a change of DNA winding, strand but not to DNA compaction. Investigated compounds show very high cytotoxic activity against cancer cell lines. All compounds exhibit efficient in vitro antitumor activity toward Jurkat (T-cell leukemia), CL-1 (T-lymphoblastoid cell line), GL-1 (B cell lymphoma cell line) and D-17 (canine osteosarcoma). The DBTsbz is more effective then carboplatin against canine osteosarcoma.

Butyltin(IV) 2-sulfobenzoates: synthesis, structural characterization and their cytostatic and antibacterial activities

Three butyltin complexes with 2-sulfobenzoic acid [Sn(C(4)H(9))(2){O(3)SC(6)H(4)COO-2}(H(2)O)]·(C(2)H(5)OH) (1), [Sn(C(4)H(9))(3){O(3)SC(6)H(4)COOH-2}] (2) and [Sn(2)(C(4)H(9))(6){μ-O(3)SC(6)H(4)COO-2}] (3) have been synthesized and characterized by IR and (1)H, (13)C and (119)Sn NMR spectra. They show interesting properties in solid state and solutions because there are many modes of coordination of the Sbz ligand. The structure of complex 1 has been determined by X-ray crystallography. It is a chain compound with 2-sulfonatobenzoate coordinated to Sn atoms as a bridging and chelate ligand via O atoms of COO and SO(3) groups. In solutions the chains dissociate giving mainly mononuclear complexes. The NMR spectra and calculation at the DFT B3LYP/3-21G** level indicate that in solutions of compounds 1, 2 and 3 in polar solvents, many complexes showing dynamic properties are formed. Density functional theory (DFT) calculations showed that many five- and six-coordinate isomers and conformers can exist in equilibrium. All compounds effectively interact with AMP and ATP. The NMR spectra showed that nucleotides are coordinated to Sn atoms via PO(4) groups. The complexes are very active cytostatic agents against tumor strains. They are more effective than cisplatin. It is interesting that activity of 3 against non-tumor cell NHDF is lower than against tumor cells. Antibacterial activity of 1 and 2 has been investigated. Compound 2 is a very effective agent against Gram-positive bacteria. Antibacterial activity of 1 is lower than that of 2. Activity of 1 both against Gram-positive and Gram-negative bacteria is similar.

Transport and cytotoxicity of the anticancer drug 3-bromopyruvate in the yeast Saccharomyces cerevisiae

We have investigated the cytotoxicity in Saccharomyces cerevisiae of the novel antitumor agent 3-bromopyruvate (3-BP). 3-BP enters the yeast cells through the lactate/pyruvate H(+) symporter Jen1p and inhibits cell growth at minimal inhibitory concentration of 1.8 mM when grown on non-glucose conditions. It is not submitted to the efflux pumps conferring Pleiotropic Drug Resistance in yeast. Yeast growth is more sensitive to 3-BP than Gleevec (Imatinib methanesulfonate) which in contrast to 3-BP is submitted to the PDR network of efflux pumps. The sensitivity of yeast to 3-BP is increased considerably by mutations or chemical treatment by buthionine sulfoximine that decrease the intracellular concentration of glutathione.

Cytotoxic effects of two organotin compounds and their mode of inflicting cell death on four mammalian cancer cells

In this report, we have tested the cytotoxicity of two organotin (OT) compounds by flow cytometry on a panel of immortalized cancer cell lines of human and murine origin. Although the OT compounds exhibited varying levels of cytotoxicity, diphenylmethyltin chloride was more toxic than 1,4-bis (diphenylchlorostannyl)p-xylene on all cell lines tested. The OT compounds were found to be highly cytotoxic to lymphoma cell lines with lower toxicity toward the HeLa cervical cancer cell line. In order to discern the mechanism by which cell death was induced, additional experiments were conducted to monitor characteristic changes consistent with apoptosis and/or necrosis. Cell lines treated with the experimental compounds indicated that there was no consistent mode of cell death induction. However, both compounds induced apoptosis in the pro-B lymphocyte cell line, NFS-70. The work presented here also demonstrates that the two OT compounds possess selective cytotoxicity against distinct transformed cell lines.