Antibacterial activity of free or nanoparticles-loaded violacein

Author(s)

Dorival Martins Junior

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2009-02-03

Examining board members

Marcelo Brocchi; Elsa Masae Mamizuka; Marcelo Lancellotti

• Advisor: Marcelo Brocchi

Abstract

Since violacein - an antibiotic, antiviral and antiparasitic compound - exhibits poor solubility in water, polymeric nanoparticles containing this compound could improve its solubility in water and biological activities. Therefore, the aim of this work was the preparation and characterization of biodegradable and biocompatible poly-D,L-(lactide-co-glycolide) 50:50 nanoparticles loading violacein to further evaluation of their antibiotic activity in vitro and in vivo. The nanoparticles were prepared by nanoprecipitation method and characterized in terms of average diameter and Zeta potential, drug loading and polymer recovery, in vitro release kinetics, in vitro and in vivo antibacterial activity against Staphyloccocus aureus strains. Nanoparticles with diameter between 116 and 139 nm and negative-charged outer surface were obtained. Drug loading efficiency and polymer recovery were 87% and 93%, respectively. In vitro release kinetics assays showed that violacein loaded in these nanoparticles has sustained release profile until 5 days of analysis. The system exhibited antibacterial activity in vitro and in vivo against Staphylococcus aureus methicilin-resistant (MRSA) strains and no significant activity against Gram-negative Enterobacteriaceae. Nanoparticles-loaded violacein was at least two times more efficient as antibiotic compound than free violacein both in vitro and in vivo. Also, this system presented additive interactions when combined with ß-lactam antibiotics and strong synergic interactions when combined with protein synthesis inhibitors. (AU)