Prospecção de bioatividade de peptídeos e proteínas de baixo peso molecular extraídos das sementes de Erythrina velutina e Amburana cearensis

Abstract

The search for alternatives to the use of conventional chemical agents in pest control and vector insects has increased. Plant proteins and peptides are one of those alternatives that cause less negative environmental interference. Thus, this work proposes the prospection of proteins and peptides of Erythrina velutina and Amburana cearensis seeds, two native species of the caatinga biome, which is still little explored as to the biological potential of its species. The seeds of each species were separated into tegument and cotyledons in order to produce four different extracts. To obtain the peptide fraction, two precipitations were performed, one at 90% with ammonium sulfate and the other at 80 ° C / 15 '. Then in an SDS-containing gel the electrophoretic profile was observed, which showed the presence of polypeptides from 97 kDa as well as peptides below 18 kDa. The inhibitory activity of protease extracts was evaluated by trypsin assays, 99.08% for coumarin cotyledon; 89.91% for multilgu cotyledon and 68.35% and 63.30% for Cumaru and Mulungu integument respectively. The antimicrobial potential of each extract for phytopathogenic fungi: Alternaria alternata, Macrophomina phaseolina, Monosporascus cannoballus and Rhizotonia solani was evaluated by two methods: disk diffusion (well variation) and dilution in agar. For the bacteria: Escherichia coli and Staphylococus aureus a microdilution was performed. The extracts had no antimicrobial potential for fungi and bacteria, under the evaluation conditions used. In evaluating the larvicidal potential of coumarin cotyledon and cotyledon extracts of mulungu in an artificial diet for the Caupi bean pest, Callosobruchus maculatus, we observed that the cotyledon extract of cumaru from 1.6% was already able to reduce the mass of the larvae, compromising its growth and survival. For the cotyledon extracts of mulungu larvae were not observed from the concentration of 0.1%. The extracts were also evaluated for their larvicidal potential for the insect vector Aedes aegypti, where extracts of coumarid cotyledons caused 100% mortality for L1 in concentrations of 5 mg / mL and 10 mg / mL in 24 hours of incubation. The extract of mulungu cotyledons had an average mortality of 33.33% in 48 hours. The 2 mg / mL cumaru integument extract promoted the mortality of 71.66% of the larvae and the integument of mulungu 18.33%. The proteins and peptides obtained did not present antimicrobial activity, but the extracts of both seeds are rich sources of molecules, peptides and bioactive proteins with larvicidal potential, that should be better investigated for identification of the molecule and association with the mechanism of action against the two species of insects.