In vitro assessment of NaF/Chit supramolecular complex: Colloidal stability, antibacterial activity and enamel protection against S. mutans biofilm.

OBJECTIVES: This study assessed the effect of NaF/Chit suspensions on enamel and on S. mutans biofilm, simulating application of a mouthrinse. METHODS: The NaF/Chit particle suspensions were prepared at molar ratio [NaF]/Chitmon]≈0.68 at nominal concentrations of 0.2 % and 0.05 % NaF and characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering and zeta potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. The S. mutans biofilm was formed for 7 days on eighty human enamel blocks that were divided into eight groups (n = 10/group): i) 0.05 % NaF solution; ii) 0.31 % Chit solution; iii) NaF/Chit(R=0.68) suspension at 0.05 % NaF; iv) 1.0 % HAc solution (Control); v) 0.2 % NaF solution; vi) 1.25 % Chit solution; vii) NaF/Chit(R=0.68) suspension at 0.2 % NaF; viii) 0.12 % chlorhexidine digluconate. The substances were applied daily for 90 s. S. mutans cell counts (CFU/mL) were performed, and the Knoop microhardness (KHN) of enamel samples were measured before and after biofilm formation. The KHN and CFU/mL data were analyzed by repeated measure ANOVA and Tukey's test (α = 0.05). RESULTS: Interactions between NaF and Chit were evidenced in solid state by FTIR spectra. The NaF/Chit complexes showed spontaneous microparticle formation and colloidal stability. The MIC and MBC ranged from 0.65 to 1.31 mg/mL. The NaF/Chit(R=0.68) suspension at 0.2 %NaF Group showed lower CFU/mL values than other groups. The NaF/Chit(R=0.68) suspensions Groups had the highest KHN values after biofilm formation. CONCLUSIONS: The NaF/Chit(R=0.68) complexes exhibited an antibacterial effect against S. mutans biofilm and reduced the enamel hardness loss. CLINICAL SIGNIFICANCE: The NaF/Chit(R=0.68) suspensions showed potential to be used as a mouthrinse for caries prevention.

Hydrophobic nanoprecipitates formed by benzoylphenylureas and ß-cyclodextrin inclusion compounds: synthesis, characterization and toxicity against aedes aegypti larvae.

The aim of this work was to synthesize and characterize the inclusion compounds formed by the complexation of ß-cyclodextrin (ßCD) with insecticides from the class of benzoylphenylureas (BPUs), named novaluron (NOV) and diflubenzuron (DIF), beyond evaluate their larvicidal activity against Aedes aegypti larvae. Solid state characterization by FTIR showed changes in the main peaks of BPUs and ßCD, suggesting the formation of inclusion compounds in solid phase. DTA and TGA thermal analysis showed changes in temperatures of BPUs decomposition as result of molecular interactions. 1H NMR experiments allowed to observe the occurrence of interactions in solution through changes in chemical shifts of BPUs aromatic hydrogens. However, the presence of H-H intermolecular correlations in 2D ROESY was found only for the DIF/ßCD complex, suggesting different topology for each complex. Such hypothesis was corroborated by thermodynamic analysis using ITC, which showed different profile of titration curves, beyond endothermic and exothermic interactions for NOV/ßCD and DIF/ßCD complexes, respectively. DLS titrations of BPUs or BPUs/ßCD DMSO solutions in aqueous solution demonstrated that the spontaneously formed hydrophobic nanoprecipitates (HNPs) have different profile of sizes depending on the BPU/ßCD system, corroborating also with the hypothesis about the existence of different topologies for each complex. Finally, the HNPs of inclusion compounds showed to be more efficient than free BPUs, allowing proposing a new insecticide formulation.

Novel triphenylantimony(V) and triphenylbismuth(V) complexes with benzoic acid derivatives: structural characterization, in vitro antileishmanial and antibacterial activities and cytotoxicity against macrophages.

Two novel organoantimony(V) and two organobismuth(V) complexes of the type ML2 were synthesized, with L = acetylsalicylic acid (HL1) or 3-acetoxybenzoic acid (HL2) and M = triphenylantimony(V) (M1) or triphenylbismuth(V) (M2). Complexes, [M1(L1)2] (1), [M1(L2)2]∙CHCl3 (2), [M2(L1)2], (3) and [M2(L2)2] (4), were characterized by elemental analysis, IR and NMR. Crystal structures of triphenylantimony(V) dicarboxylate complexes 1 and 2 were determined by single crystal X-ray diffraction. Structural analyses revealed that 1 and 2 adopt five-coordinated extremely distorted trigonal bipyramidal geometries, binding with three phenyl groups in the equatorial position and two deprotonated organic ligands (L) in the axial sites. The metal complexes, their metal salts and ligands were evaluated in vitro for their activities against Leishmania infantum and amazonensis promastigotes and Staphylococcus aureus and Pseudomonas aeruginosa bacteria. Both the metal complexes showed antileishmanial and antibacterial activities but the bismuth complexes were the most active. Intriguingly, complexation of organobismuth(V) salt reduced its activity against Leishmania, but increased it against bacteria. In vitro cytotoxic test of these complexes against murine macrophages showed that antimony(V) complexes were the least toxic. Considering the selectivity indexes, organoantimony(V) complexes emerge as the most promising antileishmanial agents and organobismuth(V) complex 3 as the best antibacterial agent.