Banca de QUALIFICAÇÃO: LUCAS GABRIEL PITA DOS SANTOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUCAS GABRIEL PITA DOS SANTOS
DATE: 10/11/2023
TIME: 14:00
LOCAL: Goole meet
TITLE:

Chemical Characterization of Annona Squamosa Lim Leaf Preparations and Investigation of Insecticide and Antimicrobial Potential

KEY WORDS:

Bibliometric analysis; custard apple; dengue mosquito; maize weevil; non-target toxicity; insecticidal formulation

PAGES: 80
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Saneamento Aplicado a Saúde do Homem
SUMMARY:

The high environmental toxicity of the currently used insecticides and the emergence of resistant insect populations have led to the search for new agents to control insect pest populations. Another current problem is the mastitis occurrence, which causes serious damage to dairy farming worldwide. In this sense, the aims of this thesis were: I - Review the state of the art and recent trends on the topic of insecticidal activity of natural products against insect species that act as urban and agricultural pests, or disease vectors; II - Characterize the Annona squamosa leaf extract for the presence of secondary metabolites, lectins and trypsin inhibitors; III – Investigate the extract for toxicity to Aedes aegypti, Sitophilus zeamais and Nasutitermes corniger, as well as non-target organisms of the Hyalella genus; IV – Develop a solid tablet-type formulation based on A. squamosa leaf extract, and evaluate its effects on Ae. aegypti larvae; and V - Investigate the antimicrobial potential of the extract against isolates of goat mastitis. Recent trends in research involving plant bioactives against Ae. aegypti, S. zeamays and N. corniger was reviewed through bibliometric analysis. The A. squamosa leaves were dried and homogenized (10 g) with 0.15M NaCl (100 mL). After centrifugation and dialysis, the supernatant free of suspended material corresponded to the extract that was analyzed by high-performance liquid chromatography. Protein concentration was then determined by colorimetric method, as well as the presence of lectins using rabbit erythrocytes, and the protease inhibitory activity using commercial trypsin and the substrate Nα-Benzoyl-DL-arginine 4-nitroanilide (BApNA). The insecticidal potential of the extract was investigated against third instar larvae (L3) of Ae. aegypti, S. zeamays adults, as well as N. corniger workers and soldiers, while non-target toxicity was evaluated for the microcrustacean Hyalella sp. The leaf extract-based larvicidal tablets were produced and investigated for the effects on survival and midgut morphology of L3. In addition, the effect of the extract on the growth of goat mastitis isolates was investigated. The bibliometric analysis revealed the concentration of research on the insecticidal activity of natural products in tropical regions of the world, where there is a greater occurrence of diseases caused by Ae. aegypti, which corresponded to the largest number of reports, compared to N. corniger and S. zeamais. Furthermore, the synthesis of metallic nanoparticles from natural products has strongly emerged as a current trend. The characterization of the extract revealed the presence of cinnamic acid derivatives, rutin and chlorogenic acid, in addition to proteins (22.9 mg/mL), including lectins (21,333.33 UAHS) and trypsin inhibitors (15.6 U/mg). The extract caused mortality (LC50 = 1.9% m/v) and altered the permeability of the peritrophic membrane of Ae. aegypti larvae, as well as exerted a strong food deterrent effect and killed adult S. zemais with mortality rates ranging from 51.2% to 63.8%. The extract did not affect the survival of N. corniger soldiers and workers, but juvenile Hyallela sp. were strongly sensitive to the treatment. The tablets based on leaf extract killed 47% of L3 at a concentration equivalent to the LC50 of the free extract and caused damages to the larval midgut morphology, including hypertrophy of the epithelium and the synthesis of apocrine vesicles. The extract was not able to interfere with the growth of bacteria that cause goat mastitis. In conclusion, the A. squamosa leaf extract kills Ae. aegypti L3 and S. zeamais adults, by increasing the permeability of the peritrophic membrane and exhibiting a strong food deterrent effect, respectively. However, the use of the extract needs caution due to its high non-target toxicity. The effects of the extract may be linked to the presence of lectins, trypsin inhibitors, rutin and chlorogenic acid. The leaf extract-based tablet was successfully synthesized and killed L3 by causing damage to the larval midgut structure. Furthermore, recent trends in research with metallic nanoparticles from plant extracts can be taken into consideration for future formulations to increase the stability and larvicidal efficacy of the A. squamosa leaf extract.

COMMITTEE MEMBERS:
Presidente - EMMANUEL VIANA PONTUAL
Interna - TATIANA SOUZA PORTO
Externa à Instituição - LEYDIANNE LEITE DE SIQUEIRA PATRIOTA - UFPE