Síntese, caraterização e estudo de derivados anfifílicos de quitosana: estudo in vitro contra os fungos Aspergillus flavus e Aspergillus parasiticus
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Data
2013-01-18
Autores
Souza, Ricchard Hallan Félix Viegas de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A quitosana e seus derivados têm se mostrado muito atrativos para a indústria de alimentos, visando principalmente a sua conservação. No presente trabalho foram sintetizados e caracterizados derivados de quitosana contendo grupos quaternários de amônio com proporções crescentes de grupos hidrofóbicos com o objetivo de investigar a atividade fungicida desses derivados contra os fungos Aspergillus flavus e Aspergillus parasiticus que são um problema na contaminação do amendoim e outros grãos. Os derivados foram sintetizados usando quitosana desacetilada e a reação foi realizada em duas etapas, sendo a primeira a quaternização do polímero com brometo de propiltrimetilamônio seguido da reação de aminação redutiva com dodecilaldeído. Os derivados foram caracterizados por RMN 1 H e os graus de substituição pelo grupo dodecil foram variados para melhorar a atividade antifúngica dos derivados. A atividade antifúngica da quitosana desacetilada e seus derivados foi testada variando-se a concentração dos polímeros de 0,1 a 1,0 g/L. Os resultados mostraram que a quitosana substituída com grupos propil exibiu uma baixa inibição contra o fungo Aspergillus flavus, resultado similar àquele obtido com quitosana desacetilada. Quanto aos derivados anfifílicos com conteúdo crescente de grupos dodecil, observou-se um aumento no índice de inibição com o aumento da concentração e do conteúdo hidrofóbico. A partir de 0,5 g/L os derivados anfifílicos contendo de 10% a 30% de grupos dodecil e 83% de grupos quaternários inibiram completamente o crescimento do fungo. Resultados similares foram obtidos no estudo de inibição do fungo Aspergillus parasiticus
Chitosan and its derivatives have been shown very attractive for the food industry, mainly targeting its conservation. In this study were synthesized and characterized chitosan derivatives containing quaternary ammonium groups with increasing proportions of hydrophobic groups in order to investigate the antifungal activity of these derivatives against the fungi Aspergillus flavus and Aspergillus parasiticus that are a problem in the contamination of peanuts and other grains. The derivatives were synthesized using deacetylated chitosan and the reaction was carried out in two steps, first the quaternization of the polymer with propyltrimethylammonium bromide followed by reductive amination reaction with dodecylaldehyde. The derivatives were characterized by 1 HNMR and the degree of substitution by the group dodecyl was varied to enhance the antifungal activity of the derivatives. The antifungal activity of deacetylated chitosan and their derivatives was tested by varying the concentration of the polymers 0.1 to 1.0 g/L. The results showed that chitosan substituted with propyl groups exhibited a low inhibition against the fungus Aspergillus flavus, a result similar to that obtained with chitosan deacetylated. Regarding the amphiphilic derivatives with increasing content of dodecyl groups, we observed an increase in the rate of inhibition with increased concentration and hydrophobic content. Since 0.5 g/L amphiphilic derivatives containing from 10% to 30% dodecyl groups and 83% of quaternary groups inhibited completely growth of the fungus. Similar results were obtained in the study of inhibition of Aspergillus parasiticus
Chitosan and its derivatives have been shown very attractive for the food industry, mainly targeting its conservation. In this study were synthesized and characterized chitosan derivatives containing quaternary ammonium groups with increasing proportions of hydrophobic groups in order to investigate the antifungal activity of these derivatives against the fungi Aspergillus flavus and Aspergillus parasiticus that are a problem in the contamination of peanuts and other grains. The derivatives were synthesized using deacetylated chitosan and the reaction was carried out in two steps, first the quaternization of the polymer with propyltrimethylammonium bromide followed by reductive amination reaction with dodecylaldehyde. The derivatives were characterized by 1 HNMR and the degree of substitution by the group dodecyl was varied to enhance the antifungal activity of the derivatives. The antifungal activity of deacetylated chitosan and their derivatives was tested by varying the concentration of the polymers 0.1 to 1.0 g/L. The results showed that chitosan substituted with propyl groups exhibited a low inhibition against the fungus Aspergillus flavus, a result similar to that obtained with chitosan deacetylated. Regarding the amphiphilic derivatives with increasing content of dodecyl groups, we observed an increase in the rate of inhibition with increased concentration and hydrophobic content. Since 0.5 g/L amphiphilic derivatives containing from 10% to 30% dodecyl groups and 83% of quaternary groups inhibited completely growth of the fungus. Similar results were obtained in the study of inhibition of Aspergillus parasiticus
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Palavras-chave
Quitosana, Quitina, Fungicidas, Aspergillus, Polissacarideos, Chitosan
Como citar
SOUZA, Ricchard Hallan Félix Viegas de. Síntese, caraterização e estudo de derivados anfifílicos de quitosana: estudo in vitro contra os fungos Aspergillus flavus e Aspergillus parasiticus. 2013. 75 f. Dissertação (mestrado) - Universidade Estadual Paulista Julio de Mesquita Filho. Instituto de Biociências, Letras e Ciências Exatas, 2013.