Banca de QUALIFICAÇÃO: PEDRO VITOR VALE BEZERRA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : PEDRO VITOR VALE BEZERRA
DATE: 10/01/2025
TIME: 13:30
LOCAL: Videoconferência - Link para acesso: https://meet.google.com/qdo-bbzz-dke
TITLE:

Exploring extracts from Amburana cearensis and Erythrina velutina seeds against Aedes aegypti and Aedes albopictus: larvicidal effect, intestinal proteases inhibition and morphological alterations

KEY WORDS:

Botanical insecticides; protease inhibitors; deformations

PAGES: 64
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Dengue, zika and chikungunya are a group of viral diseases transmitted by hematophagous mosquitoes that are of concern to the WHO due to episodes of emergence and reemergence, mainly in tropical countries such as Brazil. The management of arboviral diseases involves the control of arbovirus vectors by chemical insecticides. Aedes aegypti and Aedes albopictus mosquitoes are the main urban and periurban vectors. The use of synthetic chemicals has disadvantages such as environmental toxicity and the development of resistance in mosquito populations. Botanical insecticides such as plant extracts represent a promising alternative to this problem, due to their biodegradability and diversity of deleterious effects. However, it is necessary to identify their modes of action to indicate their use in vector control programs. In this context, this study investigated extracts from two seeds of Caatinga legumes, Amburana cearensis A.C.Sm. and Erythrina velutina Willd, as potential candidates for larvicides against A. aegypti and A. albopictus. The research focused on the inhibition of larval digestive proteases, based on the presence of serine protease inhibitors in legume seeds. Morphological changes in the larvae were also recorded to identify other possible modes of action of the extracted molecules. The extracts were obtained by solubilizing the seed powder in distilled water (1:10, w/v) at 80 °C. Lethal doses were calculated from larvicidal bioassays in which L4 larvae were exposed to different extracts concentrations. Zymography technique were developed to detect the presence of inhibition in the digestive protease profile of larvae exposed to the extracts. The morphological changes were recorded using a stereoscopic microscope cou- pled to a camera. The A. cearensis extract was more lethal for both vector species (A. aegypti - LC50 48h = 228 ppm; A. albopictus - LC50 48h = 105 ppm) compared to the E. velutina extract (A. aegypti - LC50 48h = 1866 ppm; A. albopictus - LC50 48h = 1847 ppm). In the intestinal protease inhibition analysis, the A. cearensis extract was able to reduce the enzymatic activity in both Aedes species, confirming this mode of action as a contributor to the larvicidal activity, especially in A. albopictus, where the reduction was above 70%. The development of larvae in the A. cearensis extract was monitored for 15 days, from L1 to adult. The developmental delay in A. albopictus confirms the impact of the inhibition promoted by the A. cearensis extract. In contrast, the E. velutina extract was not able to reduce the proteolytic activity of digestive enzymes of the exposed larvae, ruling out the hypothesis of this mode of action as a contributor to the larvicidal activity. The morphological alterations indicated the presence of other deleterious effects in the extracts: inhibition of acetylcholinesterase (A. cearensis and E. velutina), disruption of chitin synthesis and infection or internal tissue damage leading to melanization (E. velutina). The results of this study indicate the A. cearensis extract as a better candidate for the bo- tanical larvicide development for the control of Aedes and direct future investigations to better understand the effect of plant molecules on vector mosquitoes.

COMMITTEE MEMBERS:
Externo à Instituição - CÁSSIO LÁZARO SILVA INÁCIO
Presidente - 1149356 - ELIZEU ANTUNES DOS SANTOS
Interno - 2213126 - VALTER FERREIRA DE ANDRADE NETO