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Xylitol (xylH 5 ) is metabolized via the pentose pathway in humans, but it is unsuitable as an energy source for many microorganisms where it produces a xylitol-induced growth inhibition and disturbance in protein synthesis. For this reason, xylitol is used in the prophylaxis of several infections. In the search of better antimicrobial agents, new copper and zinc complexes with xylitol were synthesized and characterized by analytical and spectroscopic methods: Na 2 [Cu 3 (xylH − 4 ) 2 ]·NaCl·4.5H 2 O (Cu-xyl) and [Zn 4 (xylH − 4 ) 2 (H 2 O) 2 ]·NaCl·3H 2 O (Zn-xyl). Both copper and zinc complexes presented higher MIC against Pseudomona aeruginosa than the free xylitol while two different behaviors were found against Candida albicans depending on the complex. The growth curves showed that Cu-xyl presented lower activity than the free ligand during all the studied period. In the case of Zn-xyl the growth curves showed that the inhibition of the microorganism growth in the first stage was equivalent to that of xylitol but in the second stage (after 18 h) Zn-xyl inhibited more. Besides, the PAE (post agent effect) obtained for Zn-xyl and xyl showed that the recovery from the damage of microbial cells had a delay of 14 and 13 h respectively. This behavior could be useful in prophylaxis treatments for infectious diseases where it is important that the antimicrobial effect lasts longer. With the aim to understand the microbiological activities the analysis of the particle size, lipophilicity and Zn uptake was performed. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis, characterization and comparative biological study of a series of antibacterial copper complexes with heterocyclic sulfonamides were reported. Two kinds of complexes were obtained with the stoichiometries [Cu(L)2]·H2O and [Cu(L)2(H2O)4]· nH2O. They were characterized by infrared and electronic spectroscopies and the crystal structure of [Cu(sulfisoxazole)2(H2O)4]·2H2O was determined by single crystal X-ray diffraction. It crystallized in the C2/c with Z =8 monoclinic space group C2/c with Z =8. The Cu(II) is in a slightly tetragonal distorted octahedron formed by four oxygen atoms from water molecules and two nitrogen atoms from two isoxazole rings. The antimicrobial activity was evaluated for all the synthesized complexes and ligands using the agar dilution test. The results showed that the complexes with five-membered heterocyclic rings were more active than the free sulfonamides while the pyrimidine, pyridine and pyridazine complexes had similar or less activity than the free ligands. In order to find an explanation for this behavior lipophilicity and superoxide dismutase-like activity were tested, showing that the [Cu(sulfamethoxazol)2(H2O)4]·3H2O presented the highest antimicrobial potency and a superoxide dismutase-like activity comparable with pharmacological active compounds. [Copyright &y& Elsevier]

Two novel Cu(II)–dipeptide complexes containing l-histidyl–l-glycine and l-histidyl–l-alanine as ligands were prepared and characterised by infrared and electronic spectroscopies. EPR measurements were also made in solution and in the solid state. Cyclic voltammetric studies were carried out on aqueous solution. The crystalline structure of the [Cu(l-histidyl–l-glycine)2(H2O)2]·6H2O was determined by X-ray diffractometry. It crystallises in the space group C2. The Cu(II) is in a tetragonally distorted octahedral coordination, where the basal plane is occupied by N-atoms belonging to the histidine portion. The apical positions are occupied by two molecules of water. [Copyright &y& Elsevier]

Abstract: A new complex, [Cu2(sulfameter)4]3 ·2.5H2O (sulfameter=4-amino-N-(5-methoxy-2-pyrimidinyl)benzenesulfonamide), has been synthesized. Its structure has been determined by single-crystal X-ray diffraction and its spectroscopic properties (EPR, IR, Raman, UV–Vis) have been analyzed. The structure presented three different dimeric units in the unit cell and the EPR spectra, characteristic of antiferromagnetically coupled dimers, revealed two magnetically different dimeric environments. [Copyright &y& Elsevier]