Diversidade fúngica cultivável do habitat aquático de Anopheles darlingi Root, 1926 e seu potencial larvicida e antiplasmodial

Abstract

The mosquitoes Anopheles darlingi Root, 1926 and Aedes aegypti Linnaeus, 1762, are insects of great importance to public health because they are vectors of several etiological agents of human diseases, such as malaria, dengue, chikungunya, urban yellow fever, and Zika. The control of these vectors is the most efficient tool to contain the transmission of these pathogens. Some fungi and their metabolites are effective in controlling tropical disease vectors at different stages of development. The interaction between fungi and immature forms, in their breeding sites, is a relevant factor to know and establish strategies to control the transmission of these diseases. Thus, the main objective of this work was to investigate the cultivable fungal diversity obtained from aquatic environments of Anopheles darlingi larvae and its metabolites for use in the control of Ae. aegypti, Plasmodium falciparum and Candida. This work was divided into five chapters. In the chapter, I addressed the study of the diversity and fungal richness of the breeding sites of An. darlingi larvae. A total of 206 fungal strains were isolated and grouped and classified into 30 morphotypes. The identified morphotypes belonged to three phyla, five classes, ten orders, 25 families, and 26 genera of fungi. In chapter II the identification of fungal species isolated from aquatic environments in the Amazon region was carried out. A total of 55 fungal isolates were investigated, and from the phylogenetic analyses of the sequences obtained by sequencing the ITS 1 and 2 regions, 28 fungi were identified to the species level, 21 as possible new species, five were identified as sp., and one isolate was identified only to the family level. Chapter III presents the study of fungal strains of the metabolites with larvicidal activity against Ae. aegypti. A total of 72 crude extracts of 36 fungi were studied, 15 fungal extracts of the liquid culture medium showed larvicidal activity equal to or greater than 50% and, of these, eight were able to kill more than 90% of the larvae in up to 72 h, demonstrating high larvicidal potential. In chapter, IV is the selection of 20 extracts in a bioguided study for the in vitro antiplasmodial activity of bioactive extracts, fractions, and substances from the fungus Diaporter sp. - 1242. This study allowed the isolation and identification of one class and one substance with high antiplasmodial activity against the multidrug resistant strain of P. falciparum K1 (CI50 of 0.0179 μg/mL). In chapter V the antimicrobial and cytotoxic activity of metabolites extracted from mycelia of the previously isolated fungi was evaluated. The tested extracts showed antimicrobial potential, being five extracts active against Candida strains and of the active extracts, two were potentially cytotoxic. Therefore, the results obtained in this work confirm that the aquatic environments of An. darlingi larvae present a high microbial diversity, being this environment a good candidate for the discovery of new fungal species. The metabolites of the isolated fungi show larvicidal activity against Ae. aegypti, antiplasmodial activity against P. falciparum, and antifungal activity against Candida strains.