Síntese e atividade antimicrobiana de filmes biopoliméricos de dietilaminoetil quitosana de alta massa molecular
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Data
2019-03-08
Autores
Cunha, Otávio da Mata
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os derivados de quitosana (CH) substituídos com grupos dietilaminoetil (CHDEAE) e DODECIL (CH-DEAE-DD), mostram excelente atividade de inibição contra os fungos Aspergillus flavus e Aspergillus parasiticus e a atividade antimicrobiana está relacionada com o grau de modificação estrutural, concentração e massa molecular dos polímeros. Partindo deste pressuposto, o presente trabalho teve como objetivo a obtenção de filmes processados a partir desses derivados com potencial aplicação como revestimento comestivel na conservação pós-colheita de frutas e hortaliças. A atividade antimicrobiana dos filmes foi avaliada contra os fungos Alternaria solani, Alternaria alternata e Penicillium expansum que impactam a produção e conservação de alimentos. Para a obtenção dos filmes, primeiramente modificou-se a estrutura da quitosana de alta massa molecular (Mw), 282 KDa, pela reação de substituição por grupos DEAE seguida da reação com dodecilaldeído e posterior redução com borohidreto de sódio. A quitosana e seus derivados foram caracterizados por RMN ¹H, obtendo-se graus de substituição (GS) de 40% de grupos DEAE e 3% de DD. Os filmes biopoliméricos foram obtidos por “casting” e caracterizados por Espectroscopia de Infravermelho com Transformada de Fourier (FTIR). As análises de Termogravimetria (TG) indicaram que a adição de plastificantes, glicerol e sorbitol, resulta na formação de uma blenda polimérica e os resultados das propriedades mecânicas corroboraram com essa análise, uma vez que as modificações químicas realizadas na estrutura quitosana propiciaram uma melhor maleabilidade nos filmes biopoliméricos. As imagens dos filmes obtidas por Microscopia Eletrônica de Varredura (MEV) e Microscopia de Força Atômica (AFM) mostraram uma superfície lisa, sem porosidade e rachaduras. A difração de Raios X (DRX) mostrou que os derivados de quitosana sintetizados possuem uma estrutura mais amorfa que a quitosana comercial. A citotoxicidade dos polímeros foi avaliada utilizando células 3T3 e mostraram viabilidade celular acima de 90% para todos os polímeros, indicando que esse material pode ser usado como revestimento de frutas e sementes. Os resultados da atividade antimicrobiana in vitro mostrou que os filmes biopoliméricos de derivados anfifílicos de quitosana são mais eficazes que filmes de CH contra os fungos Alternaria e Penicillium. Para o recobrimento de frutas, os resultados mostraram que o filme CH-DEAE-DD apresentou uma melhor eficiência na conservação de alimentos.
Chitosan (CH) derivatives substituted with diethylaminoethyl (CH-DEAE) and DODECIL (CH-DEAE-DD) groups show excellent inhibition activity against fungi Aspergillus flavus and Aspergillus parasiticus and antimicrobial activity is related to the degree of modification structural, concentration and molecular mass of the polymers. Based on this assumption, the present study had the objective to obtain films processed from these derivatives with potential application as edible coating in the post-harvest conservation of fruits and vegetables. The antimicrobial activity of the films was evaluated against the fungi Alternaria solani, Alternaria alternata and Penicillium expansum that impact the production and conservation of foods. To obtain the films, the structure of the high molecular weight chitosan (Mw), 282 KDa, was first modified by the substitution reaction by DEAE groups followed by the reaction with dodecyl aldehyde and subsequent reduction with sodium borohydride. Chitosan and its derivatives were characterized by ¹H NMR, obtaining degrees of substitution (DS) of 40% of DEAE groups and 3% of DD. The biopolymer films were obtained by casting and characterized by Infrared Spectroscopy with Fourier Transform (FTIR). The thermogravimetric (TG) analyzes indicated that the addition of plasticizers, glycerol and sorbitol, results in the formation of a polymer blender and the results of the mechanical properties corroborated with this analysis, since the chemical modifications carried out in the chitosan structure provided better malleability in biopolymer films. The images obtained by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed a smooth surface with no porosity and cracking. X-ray diffraction (XRD) showed that the synthesized chitosan derivatives have a more amorphous structure than the commercial chitosan one. The cytotoxicity of the polymers was assessed using 3T3 cells and showed cell viability above 90% for all polymers, indicating that this material can be used as a coating of fruits and seeds. The results of the in vitro antimicrobial activity showed that the biopolymer films of amphiphilic chitosan derivatives are more effective than CH films against the fungi Alternaria and Penicillium. For the coating of fruits, the results showed that the CH-DEAE-DD film showed a better efficiency in food preservation.
Chitosan (CH) derivatives substituted with diethylaminoethyl (CH-DEAE) and DODECIL (CH-DEAE-DD) groups show excellent inhibition activity against fungi Aspergillus flavus and Aspergillus parasiticus and antimicrobial activity is related to the degree of modification structural, concentration and molecular mass of the polymers. Based on this assumption, the present study had the objective to obtain films processed from these derivatives with potential application as edible coating in the post-harvest conservation of fruits and vegetables. The antimicrobial activity of the films was evaluated against the fungi Alternaria solani, Alternaria alternata and Penicillium expansum that impact the production and conservation of foods. To obtain the films, the structure of the high molecular weight chitosan (Mw), 282 KDa, was first modified by the substitution reaction by DEAE groups followed by the reaction with dodecyl aldehyde and subsequent reduction with sodium borohydride. Chitosan and its derivatives were characterized by ¹H NMR, obtaining degrees of substitution (DS) of 40% of DEAE groups and 3% of DD. The biopolymer films were obtained by casting and characterized by Infrared Spectroscopy with Fourier Transform (FTIR). The thermogravimetric (TG) analyzes indicated that the addition of plasticizers, glycerol and sorbitol, results in the formation of a polymer blender and the results of the mechanical properties corroborated with this analysis, since the chemical modifications carried out in the chitosan structure provided better malleability in biopolymer films. The images obtained by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed a smooth surface with no porosity and cracking. X-ray diffraction (XRD) showed that the synthesized chitosan derivatives have a more amorphous structure than the commercial chitosan one. The cytotoxicity of the polymers was assessed using 3T3 cells and showed cell viability above 90% for all polymers, indicating that this material can be used as a coating of fruits and seeds. The results of the in vitro antimicrobial activity showed that the biopolymer films of amphiphilic chitosan derivatives are more effective than CH films against the fungi Alternaria and Penicillium. For the coating of fruits, the results showed that the CH-DEAE-DD film showed a better efficiency in food preservation.
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Palavras-chave
Quitosana, Derivados, Dietilaminoetil, Filmes biopoliméricos, Chitosan, Derivatives, Diethylaminoethyl, Biopolymer films