Desenvolvimento de filmes híbridos à base de quitosana e avaliação do potencial antifúngico

Abstract

The concern of society with the environment and with the increasing demand for free food waste has shown reflected in the agricultural sector. The main challenge for the research has been the search for more friendly products and less impact to human and animal health, which creates an opportunity for innovation as phytoprotection in brazilian agriculture. The use of bioactive substances such chitosan for the management of fungal diseases have shown promise. Their microbial activity has been observed against a wide range of microorganisms including fungi, algae and some bacteria. Thus, this work aims at the synthesis, structural characterization and evaluation of novel hybrid compounds to chitosan base for antifungal use in guavas which is in line with the demand of the Southern half of Rio Grande do Sul, where planting is observed in guavas with low technological level entailing opportunities for the occurrence of fungal diseases, including anthracnose, caused by Colletotrichum gloeosporioides, is one of the main. This pathogen compromises young tissues developing, and may remain quiescent for fruit until the period of maturation, to cause significant damage both in vegetative phase or post-harvest. The expression of structural barriers by host tissue after treatment with chitosan can restrict the expansion of the invading pathogen and delay the resumption of development of quiescent infections that become active with the decline of the potential biosynthetic tissue to produce antimicrobial compounds. In this study chitosan based films were developed with essential oil concentration variations Tagetes minuta Linn. and chloride copper (II). These films were characterized structurally and morphologically through infrared spectroscopy, thermal analysis, scanning electron microscopy and energy dispersive spectroscopy. Moreover, these films were evaluated for phytotoxic action in guava leaves and the potential fungitoxic C. gloeosporioides expressed by interference on mycelial growth and sporulation of the pathogen. This assessment showed that all treatments containing chitosan and T. minuta essential oil at different concentrations resulted in lower mycelial growth and sporulation compared to the control, even with the addition of chloride copper (II) 0.77 % (w/v), the formation of a hybrid film, the action of the films was potentiated.