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Water Soluble Usnic Acid-Polyacrylamide Complexes with Enhanced Antimicrobial Activity against Staphylococcus epidermidis
Department of Chemistry, "Sapienza" University of Rome, Piazzale A. Moro 5, Rome 00185, Italy
* Author to whom correspondence should be addressed.
Received: 18 February 2013; in revised form: 15 March 2013 / Accepted: 19 March 2013 / Published: 2 April 2013
Abstract: Usnic acid, a potent antimicrobial and anticancer agent, poorly soluble in water, was complexed to novel antimicrobial polyacrylamides by establishment of strong acidic-base interactions. Thermal and spectroscopic analysis evidenced a molecular dispersion of the drug in the polymers and a complete drug/polymer miscibility for all the tested compositions. The polymer/drug complexes promptly dissolved in water and possessed a greater antimicrobial activity against Staphylococcus epidermidis than both the free drug and the polymer alone. The best results were obtained with the complex based on the lowest molecular weight polymer and containing a low drug content. Such a complex showed a larger inhibition zone of bacterial growth and a lower minimum inhibitory concentration (MIC) with respect to usnic acid alone. This improved killing effect is presumably due to the reduced size of the complexes that allows an efficient cellular uptake of the antimicrobial complexes. The killing effect extent seems to be not significantly dependent on usnic acid content in the samples.
Keywords: usnic acid; polyacrylamide; antimicrobial activity; drug delivery; solubility
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MDPI and ACS Style
Francolini, I.; Taresco, V.; Crisante, F.; Martinelli, A.; D'Ilario, L.; Piozzi, A. Water Soluble Usnic Acid-Polyacrylamide Complexes with Enhanced Antimicrobial Activity against Staphylococcus epidermidis. Int. J. Mol. Sci. 2013, 14, 7356-7369.
Francolini I, Taresco V, Crisante F, Martinelli A, D'Ilario L, Piozzi A. Water Soluble Usnic Acid-Polyacrylamide Complexes with Enhanced Antimicrobial Activity against Staphylococcus epidermidis. International Journal of Molecular Sciences. 2013; 14(4):7356-7369.
Francolini, Iolanda; Taresco, Vincenzo; Crisante, Fernanda; Martinelli, Andrea; D'Ilario, Lucio; Piozzi, Antonella. 2013. "Water Soluble Usnic Acid-Polyacrylamide Complexes with Enhanced Antimicrobial Activity against Staphylococcus epidermidis." Int. J. Mol. Sci. 14, no. 4: 7356-7369.