Study of the mechanism of the antimicrobial activity of amphiphilic derivatives of chitosan using membrane models with varied charge density

• Grant number: 13/24251-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2014
• End date: December 31, 2014
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Vera Aparecida de Oliveira Tiera
• Grantee: Amanda Manchini Dias
• Host Institution: Instituto de Biociências, Letras e Ciências Exatas (IBILCE). Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. São José do Rio Preto , SP, Brazil

Abstract

We have recently shown that amphiphilic derivatives of chitosan containing secondary and tertiary amino groups allow obtaining biofungicides with activity against fungi of the genus Aspergillus. In particular, the derivatives exhibited a high antimicrobial activity against Aspergillus flavus and allowed to request a patent (TIERA et al. 2013). The results showed that the antimicrobial activity depends on the composition of the derivatives, especially the degree of substitution by hydrophobic groups, the charge density and molecular weight. Therefore, this project proposes the study of the mechanism of antimicrobial activity by the synthesis of derivatives of low molecular weight chitosan with hydrophobic content constant ( 3-5 % ) and different proportions of the diethylaminoethyl group. The project proposes the study of the interaction of different amphiphilic derivatives with model membranes prepared with L-alpha-phosphatidylcholine and L-alpha-phosphatidyl-DL-glycerol phospholipids, thus seeking to elucidate the most important parameters (hydrophobic content composition and molecular weight) to optimize antimicrobial activity. In vitro growth inhibitory studies of the derivatives against A. flavus will be performed aiming to correlate the microbiological tests with those obtained using model membranes. (AU)