Effects of Zinc Compounds on the Enzymatic Activities of Lysozyme and Peroxidase and Their Antifungal Activities

This study aimed to investigate the effects of zinc compounds on the enzymatic activities of lysozyme, peroxidase, and the glucose oxidase-mediated peroxidase (GO-PO) system and their antifungal activities. Four different zinc compounds (zinc chloride, gluconate, lactate, and sulfate) were incubated with hen egg-white lysozyme (HEWL), bovine lactoperoxidase (bLPO), the GO-PO system, and human unstimulated whole saliva in solution and on a hydroxyapatite surface. Enzymatic activities of lysozyme, peroxidase, and the GO-PO system were measured through the hydrolysis of Micrococcus lysodeikticus, oxidation of fluorogenic 2',7'-dichlorofluorescin, and glucose assay, respectively. Interactions between zinc and enzymes were analyzed by surface plasmon resonance (SPR). The minimum inhibitory concentration (MIC) and candidacidal activities of zinc compounds were examined against three Candida albicans strains. Zinc gluconate and sulfate significantly increased the enzymatic activities of salivary lysozyme in the solution assay and of HEWL and salivary lysozyme on the hydroxyapatite surface. However, all examined zinc compounds significantly decreased the enzymatic activities of bLPO and salivary peroxidase in solution and on the surface. SPR analyses revealed binding of zinc to lysozyme and peroxidase, with affinity differing according to the zinc compounds. The MIC of zinc compounds against C. albicans was 1.0-2.4 mM. Candidacidal activities were 17.7-38.8% and 23.7-47.0% at 1.0 and 10 mM concentrations, respectively. In conclusion, zinc compounds enhanced lysozyme activity but inhibited peroxidase activity. Zinc compounds exhibited concentration-dependent candidacidal activity against C. albicans. Zinc compounds are potential therapeutic agents for oral health, especially for geriatric patients.

Altering the Coordination of Iron Porphyrins by Ionic Liquid Nanodomains in Mixed Solvent Systems

The solvent environment around iron porphyrin complexes was examined using mixed molecular/RTIL (room temperature ionic liquid) solutions. The formation of nanodomains in these solutions provides different solvation environments for substrates that could have significant impact on their chemical reactivity. Iron porphyrins (Fe(P)), whose properties are sensitive to solvent and ligation changes, were used to probe the molecular/RTIL environment. The addition of RTILs to molecular solvents shifted the redox potentials to more positive values. When there was no ligation change upon reduction, the shift in the E° values were correlated to the Gutmann acceptor number, as was observed for other porphyrins with similar charge changes. As %RTIL approached 100 %, there was insufficient THF to maintain coordination and the E° values were much more dependent upon the %RTIL. In the case of Fe^III (P)(Cl), the shifts in the E° values were driven by the release of the chloride ion and its strong attraction to the ionic liquid environment. The spectroscopic properties and distribution of the Fe^II and Fe^I species into the RTIL nanodomains were monitored with visible spectroelectrochemistry, ¹⁹ F NMR and EPR spectroscopy. This investigation shows that coordination and charge delocalization (metal versus ligand) in the metalloporphyrins redox products can be altered by the RTIL fraction in the solvent system, allowing an easy tuning of their chemical reactivity.

Synthesis, characterization and bioactive evaluation of copper(II) 5,10,15,20-tetrakis[alpha,alpha,alpha,alpha-2-(2,6-bis(4-methylpiperazine-1-yl-methyl)-4-iminomethyl phenol)phenyl] porphyrin: a picket-fence porphyrin

We are interested in constructing deeper small cavities by adding more bulky substituents at the ortho-phenyl positions of tetrakis(o-aminophenyl)porphyrin. The synthesis of picket-fence porphyrin is initiated by the preparation of the tetrakis(o-nitrophenyl)porphyrin followed by the nitro to amino reduction and subsequent condensation with Schiff base ligand to form imine linkages of porphyrin complexes. The synthesis and characterization of a new series of picket-fence porphyrins and their copper complexes are described. 5,10,15,20-Tetrakis[alpha,alpha,alpha,alpha-2-(2,6-bis(4-methyl piperazine-1-yl-methyl)-4-iminomethyl phenol)phenyl] porphyrin can be synthesized from 2,6-bis[4-methylpiperazin-1-yl-methyl]-4-formylphenol (L) and 5,10,15,20-tetra[alpha,alpha,alpha,alpha-o-nitropheny1]-porphyrin. 5,10,15,20-Tetra[alpha,alpha,alpha,alpha-o-aminopheny1]-porphyrin was obtained by the reduction of 5,10,15,20-tetra[alpha,alpha,alpha,alpha-o-nitropheny1]-porphyrin. The spectral, electrochemical, antibacterial, antifungal and cytotoxicity properties of all the picket-fence porphyrin complexes were characterized and studied.