New Antibacterial Silver(I) Coordination Polymers Based on a Flexible Ditopic Pyrazolyl-Type Ligand

Cadmium and silver complexes of a pyridine containing ligand: syntheses, structural studies, biological activity and docking studies

The current study aimed to synthesize seven new metal coordination complexes (Q1-Q7) with potential biomedical applications. Novel mononuclear, polynuclear and mixed-ligand coordination compounds of the elements, cadmium(ii) and silver(i) derived from a pyridine containing ligand (2,4,6-tris-(2-pyridyl)-1,3,5-triazine (TPT)) have been synthesized successfully with the general formulae [Cd(TPT)Cl6]·H2O and [Ag x (TPT) y (L)2(ClO4)](ClO4) z (x = 1,2,3, y = 1,2,3, L = PPh3 or phen, z = 1,2). The structural features were fully characterized using various spectroscopic techniques, such as infrared, ultraviolet-visible spectroscopy, 1D and 2D-NMR (1H, 13C, 31P, 1H-1H COSY and 1H-13C HSQCAD), CHN analysis, molar conductance (Λ), thermogravimetric analysis (TGA), and powder X-ray diffraction analysis. The structure of complex Q6 was also confirmed by single-crystal X-ray analysis. The luminescence and electrochemical properties of complexes, in solution, have been studied. X-ray crystallographic determination of the [Ag(TPT)(PPh3)2]ClO4·EtOH (Q6) complex shows that the Ag+ cation is bonded to one tridentate TPT ligand through NNN set of donor atoms and two triphenylphosphine ligands, giving the Ag+ a distorted trigonal bipyramidal geometry. X-ray powder diffraction analysis showed that metal complexes Q3, Q6 and Q7 display crystalline peaks. The complexes were evaluated for their in vitro antibacterial efficacy against various bacterial and fungal species. The in vitro efficacy against the MCF-7 human breast cancer cell line was assessed to determine the anticancer activities. The tri-nuclear silver complex Q3 shows great potential as a therapeutic candidate for treating breast cancer, since it exhibits a half-maximal inhibition concentration (IC50) of 13.45 ± 0.9 μM. Molecular docking simulations were also carried out to evaluate the interaction strength and properties of the metal complexes with selected cancer and bacteria relevant proteins namely cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase 6 (CDK6), signal transducer and activator of transcription 3 (STAT3), and beta-lactamases from Escherichia coli and Staphylococcus aureus.

Silver- and Zinc-Decorated Polyurethane Ionomers with Tunable Hard/Soft Phase Segregation

Segmented polyurethane ionomers find prominent applications in the biomedical field since they can combine the good mechanical and biostability properties of polyurethanes (PUs) with the strong hydrophilicity features of ionomers. In this work, PU ionomers were prepared from a carboxylated diol, poly(tetrahydrofuran) (soft phase) and a small library of diisocyanates (hard phase), either aliphatic or aromatic. The synthesized PUs were characterized to investigate the effect of ionic groups and the nature of diisocyanate upon the structure-property relationship. Results showed how the polymer hard/soft phase segregation was affected by both the concentration of ionic groups and the type of diisocyanate. Specifically, PUs obtained with aliphatic diisocyanates possessed a hard/soft phase segregation stronger than PUs with aromatic diisocyanates, as well as greater bulk and surface hydrophilicity. In contrast, a higher content of ionic groups per polymer repeat unit promoted phase mixing. The neutralization of polymer ionic groups with silver or zinc further increased the hard/soft phase segregation and provided polymers with antimicrobial properties. In particular, the Zinc/PU hybrid systems possessed activity only against the Gram-positive Staphylococcus epidermidis while Silver/PU systems were active also against the Gram-negative Pseudomonas aeruginosa. The herein-obtained polyurethanes could find promising applications as antimicrobial coatings for different kinds of surfaces including medical devices, fabric for wound dressings and other textiles.

Quinoline Functionalized Schiff Base Silver (I) Complexes: Interactions with Biomolecules and In Vitro Cytotoxicity, Antioxidant and Antimicrobial Activities

A series of fifteen silver (I) quinoline complexes Q1-Q15 have been synthesized and studied for their biological activities. Q1-Q15 were synthesized from the reactions of quinolinyl Schiff base derivatives L1-L5 (obtained by condensing 2-quinolinecarboxaldehyde with various aniline derivatives) with AgNO3, AgClO4 and AgCF3SO3. Q1-Q15 were characterized by various spectroscopic techniques and the structures of [Ag(L1)2]NO3Q1, [Ag(L1)2]ClO4Q6, [Ag(L2)2]ClO4Q7, [Ag(L2)2]CF3SO3Q12 and [Ag(L4)2]CF3SO3Q14 were unequivocally determined by single crystal X-ray diffraction analysis. In vitro antimicrobial tests against Gram-positive and Gram-negative bacteria revealed the influence of structure and anion on the complexes' moderate to excellent antibacterial activity. In vitro antioxidant activities of the complexes showed their good radical scavenging activity in ferric reducing antioxidant power (FRAP). Complexes with the fluorine substituent or the thiophene or benzothiazole moieties are more potent with IC50 between 0.95 and 2.22 mg/mL than the standard used, ascorbic acid (2.68 mg/mL). The compounds showed a strong binding affinity with calf thymus-DNA via an intercalation mode and protein through a static quenching mechanism. Cytotoxicity activity was examined against three carcinoma cell lines (HELA, MDA-MB231, and SHSY5Y). [Ag(L2)2]ClO4Q7 with a benzothiazole moiety and [Ag(L4)2]ClO4Q9 with a methyl substituent had excellent cytotoxicity against HELA cells.