Search Results (3)

Investigating the driving forces leading to the formation of a specific supramolecular architecture among a wide spectrum of all the possibly obtainable structures is not an easy task. The contemporary literature provides several models for correctly predicting the thermodynamically accessible structures that can originate from a library of building blocks. Definitions are rigid by their very nature, so their application may sometimes require a shift in perspective. In the study presented herein, we describe the crystal structures of three metallo-supramolecular architectures assembled from deprotonated derivatives of 3,6,9-trioxaundecanedioic acid and Mn(II), Co(II) and Zn(II). In the Mn(II) case, the complexation resulted in a complex of a discrete/heptacoordinated nature, whereas the other two structures appeared as helical polymers. To explain such an anomaly, in this work, we describe how the interplay between the flexibility of the ligand spacer and the number of coordinating atoms involved determines the divergent or convergent organisation of the final coordination architecture. Full article

Drug-resistant Pseudomonas aeruginosa is rapidly developing resulting in a serious global threat. Immunocompromised patients are specifically at risk, especially those with cystic fibrosis (CF). Novel metal complexes incorporating 1,10-phenanthroline (phen) ligands have previously demonstrated antibacterial and anti-biofilm effects against resistant P. aeruginosa from CF patients in vitro. Herein, we present the in vivo efficacy of {[Cu(3,6,9-tdda)(phen)₂]·₃H₂O·EtOH}_n (Cu-tdda-phen), {[Mn(3,6,9-tdda)(phen)₂]·₃H₂O·EtOH}_n (Mn-tdda-phen) and [Ag₂(3,6,9-tdda)(phen)₄]·EtOH (Ag-tdda-phen) (tddaH₂ = 3,6,9-trioxaundecanedioic acid). Individual treatments of these metal-tdda-phen complexes and in combination with the established antibiotic gentamicin were evaluated in vivo in larvae of Galleria mellonella infected with clinical isolates and laboratory strains of P. aeruginosa. G. mellonella were able to tolerate all test complexes up to 10 µg/larva. In addition, the immune response was affected by stimulation of immune cells (hemocytes) and genes that encode for immune-related peptides, specifically transferrin and inducible metallo-proteinase inhibitor. The amalgamation of metal-tdda-phen complexes and gentamicin further intensified this response at lower concentrations, clearing a P. aeruginosa infection that were previously resistant to gentamicin alone. Therefore this work highlights the anti-pseudomonal capabilities of metal-tdda-phen complexes alone and combined with gentamicin in an in vivo model. Full article

Chronic infections of Pseudomonas aeruginosa in the lungs of cystic fibrosis (CF) patients are problematic in Ireland where inherited CF is prevalent. The bacteria’s capacity to form a biofilm in its pathogenesis is highly virulent and leads to decreased susceptibility to most antibiotic treatments. Herein, we present the activity profiles of the Cu(II), Mn(II) and Ag(I) tdda-phen chelate complexes {[Cu(3,6,9-tdda)(phen)₂]·3H₂O·EtOH}_n (Cu-tdda-phen), {[Mn(3,6,9-tdda)(phen)₂]·3H₂O·EtOH}_n (Mn-tdda-phen) and [Ag₂(3,6,9-tdda)(phen)₄]·EtOH (Ag-tdda-phen) (tddaH₂ = 3,6,9-trioxaundecanedioic acid; phen = 1,10-phenanthroline) towards clinical isolates of P. aeruginosa derived from Irish CF patients in comparison to two reference laboratory strains (ATCC 27853 and PAO1). The effects of the metal-tdda-phen complexes and gentamicin on planktonic growth, biofilm formation (pre-treatment) and mature biofilm (post-treatment) alone and in combination were investigated. The effects of the metal-tdda-phen complexes on the individual biofilm components; exopolysaccharide, extracellular DNA (eDNA), pyocyanin and pyoverdine are also presented. All three metal-tdda-phen complexes showed comparable and often superior activity to gentamicin in the CF strains, compared to their activities in the laboratory strains, with respect to both biofilm formation and established biofilms. Combination studies presented synergistic activity between all three complexes and gentamicin, particularly for the post-treatment of established mature biofilms, and was supported by the reduction of the individual biofilm components examined. Full article