Hydrophobic effect of amphiphilic derivatives of chitosan on the antifungal activity against Aspergillus flavus and Aspergillus parasiticus

Low molecular weight amphiphilic derivatives of chitosan were synthesized, characterized and their antifungal activities against Aspergillus flavus and Aspergillus parasiticus were tested. The derivatives were synthesized using as starting material a deacetylated chitosan sample in a two step proces...

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Bibliographic Details
Published in:	Molecules (Basel, Switzerland) Vol. 18; no. 4; pp. 4437 - 4450
Main Authors:	Viegas de Souza, Ricchard Hallan Felix, Takaki, Mirelli, de Oliveira Pedro, Rafael, dos Santos Gabriel, Juliana, Tiera, Marcio José, de Oliveira Tiera, Vera Ap
Format:	Journal Article
Language:	English
Published:	Switzerland MDPI AG 15-04-2013 MDPI
Subjects:	amphiphilic antifungal activity Antifungal Agents - chemistry Antifungal Agents - pharmacology Antimicrobial agents Aspergillus - drug effects Aspergillus flavus Aspergillus flavus - drug effects Aspergillus parasiticus chitosan Chitosan - chemistry Chitosan - pharmacology derivatives Hydrophobic and Hydrophilic Interactions Magnetic Resonance Spectroscopy Microbial Sensitivity Tests Molecular weight Pathogens Polymers Quaternary Ammonium Compounds - chemistry Spectroscopy, Fourier Transform Infrared
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Summary:	Low molecular weight amphiphilic derivatives of chitosan were synthesized, characterized and their antifungal activities against Aspergillus flavus and Aspergillus parasiticus were tested. The derivatives were synthesized using as starting material a deacetylated chitosan sample in a two step process: the reaction with propyltrimethyl-ammonium bromide (Pr), followed by reductive amination with dodecyl aldehyde. Aiming to evaluate the effect of the hydrophobic modification of the derivatives on the antifungal activity against the pathogens, the degree of substitution (DS₁) by Pr groups was kept constant and the proportion of dodecyl (Dod) groups was varied from 7 to 29% (DS₂). The derivatives were characterized by ¹H-NMR and FTIR and their antifungal activities against the pathogens were tested by the radial growth of the colony and minimum inhibitory concentration (MIC) methods. The derivatives substituted with only Pr groups exhibited modest inhibition against A. flavus and A. parasiticus, like that obtained with deacetylated chitosan. Results revealed that the amphiphilic derivatives grafted with Dod groups exhibited increasing inhibition indexes, depending on polymer concentration and hydrophobic content. At 0.6 g/L, all amphiphilic derivatives having from 7.0 to 29% of Dod groups completely inhibited fungal growth and the MIC values were found to decrease from 4.0 g/L for deacetylated chitosan to 0.25-0.50 g/L for the derivatives. These new derivatives open up the possibility of new applications and avenues to develop effective biofungicides based on chitosan.
ISSN:	1420-3049 1420-3049
DOI:	10.3390/molecules18044437