Antimicrobial evaluation of new metallic complexes with xylitol active against P. aeruginosa and C. albicans: MIC determination, post-agent effect and Zn-uptake

• Two new copper and zinc complexes with xylitol were developed.
• The activity against C. albicans, Gram + and Gram – bacteria was studied.
• Minimum Inhibition Concentrations were determined.
• Post-agent effect was calculated.
• Zn-uptake was measured in C. albicans after the treatment with Zn-complex.

Xylitol (xylH5) 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: Na2[Cu3(xylH− 4)2]·NaCl·4.5H2O (Cu-xyl) and [Zn4(xylH− 4)2(H2O)2]·NaCl·3H2O (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.

New copper and zinc complexes with xylitol were developed presenting better activity against C. albicans and Gram positive and negative aerobic bacteria than free xylitol. Metallomic study and the post agent effect provide information about the antimicrobial activity.Figure optionsDownload as PowerPoint slide