Quimiodiversidade de fungos endofíticos associado a estresse oxidativo em larvas de Aedes aegypti

Abstract

The Aedes aegypti mosquito is the main vector of the dengue virus, hemorrhagic dengue, chikungunya and the zika virus, which has been causing a serious public health problem worldwide. Currently, control of Ae. aegypti is carried out with synthetic larvicides, however, mosquitoes have become highly resistant to them and this makes their eradication more difficult. The emergence of insecticide-resistant mosquitoes reinforces the interest in the search for new products effective against these adult mosquitoes and in their larval state. Thus, the objective of this project was to evaluate the chemiodiversity found in the endophytic fungi isolated from Passovia stelis regarding their larvicidal potential and to understand the possible entomotoxic mechanisms induced. Thus, to achieve the objectives outlined, 104 endophytic fungi isolated in previous studies underwent reactivation, where only 6 showed viability. Each of the six fungi were grown in potato dextrose liquid medium, after the micellar growth, the broth was separated and partitioned with ethyl acetate, providing the crude extracts after evaporation of the solvent. The crude extracts obtained (Ph, FAT07, FAT46, FAT49, FAT50 and CAT20) were subjected to preliminary tests on human lung fibroblast cells (MRC-5) for analysis of cytotoxicity by the Alamar Blue method and determination of reactive species levels of oxygen using the dichlorofluorescein method. The extracts that were cytotoxic and showed production of reactive oxygen species were submitted to the larvicidal potential test against the Ae. Aegypti larvae (bioselective and dose assay). Larvae that died when exposed to the analyzed extract were subjected to quantification of the oxidative damage caused to proteins and lipids by testing reactive substances of thiobarbituric acid and quantification of carbonyl content, respectively. According to the results obtained, the Ph, CAT 20, FAT 49, FAT 46 and FAT 50 samples did not show cytotoxicity, while the FAT 07 sample was cytotoxic. All extracts tested against MRC-5 cells are producers of reactive oxygen species. The extract FAT07 showed larvicidal activity with CL50 equal to 264,456 ppm and CL90 equal to 364,307 ppm, being considered active. Additionally, it is assumed that the larvae, when submitted to the FAT07 extract, die from oxidative damage to proteins and lipids. The FAT07 extract was fractionated, and three substances were isolated, being in the process of identification by Nuclear Magnetic Resonance and Mass Spectrometry. Additionally, a bio-clock assay for antibacterial activity against Xanthomonas citri subsp. citri.