Banca de QUALIFICAÇÃO: GIULIAN CÉSAR DA SILVA SÁ

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : GIULIAN CÉSAR DA SILVA SÁ
DATE: 16/12/2020
TIME: 09:00
LOCAL: Videoconferência
TITLE:

EXTRACTS AND NANOEMULSIONS FROM Tephrosia toxicaria (Sw.) Pers. AS AEDICIDAL BIOCONTROL AND ANTIOXIDANT AGENTS

KEY WORDS:

Plant extracts; SNEDDS; Arboviruses; Aedes aegypti; Oxidative stress.

PAGES: 292
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

The exponential growth of the world population, associated with environmental imbalance and high demographics, has promoted the emergence and increase of arboviruses and chronic diseases. Arboviruses are diseases vectorized by arthropods such as Aedes aegypti, whose expansion and adaptation are favored by environmental imbalances. In turn, chronic diseases, especially those associated with oxidative stress, originate from the deregulation of physiological homeostasis of reactive species. However, there are still no completely effective resources to contain the expansion of these diseases, urging as first-line strategies the insect control by chemical insecticides and the delay or neutralization of the deleterious effects arising from oxidative stress by administration of antioxidant compounds as first-line strategies for the prevention and treatment of chronic diseases. Due to the prominence that botanical formulations have been gaining, this research aimed to investigate the aedicidal and antioxidant activities of extracts and nanoemulsions obtained from roots, stems, leaves and seeds of Tephrosia toxicaria. From these tissues and organs, eight extracts were obtained, four aqueous and four hydroethanolic, whose partial characterization revealed a protein abundance, especially cysteine protease inhibitors, in relation to the other constituents investigated. Among the extracts, hydroethanolic root extract (RHA) was the most active against Aedes aegypti larvae, with LC₅₀ of 0.33 and 0.17 mg/mL at 24 and 48 hours of exposure, respectively. A nanoemulsion was obtained from this extract (SNTt) and evaluated as larvicidal agent, whose LC₅₀ was 0.55 and 0.22 mg/mL at 24 and 48 hours of exposure. The probable mechanism of action may be associated with the fact that protease inhibitors present in RHA, both in the free and encapsulated extract, are able to bind to the proteases of the middle intestine of the larvae, promoting functional alterations, with consequent larval death. The manifestation of antioxidant activity also varied with type of extraction, vegetative part, extract concentrations and detection assay employed. Both in vitro and in vivo, the extracts were able to inhibit the accumulation of intracellular reactive species. After ranking, the hydroethanolic extract of leaves (FHA) stood out as the most promising due to the score obtained. Antioxidant activity in FHA was preserved after heating at 100 ºC for 15 minutes, suggesting that it was not linked to protein fraction. However, its chemical characterization reveals low levels of total phenolic compounds, indicating the possibility of the action of another phytochemical class in this activity. Additionally, SNTt also exhibited antioxidant activity, with more promising results than free extract (RHA) at a concentration of 0.1 mg/mL. RHA, FHA and SNTt showed no toxicity to non-cancer cell lines (3T3) and did not induce the proliferation of cancer cell lines (HepG2), stimulating their evaluation to make up anti-Aedes and antioxidant formulations.

BANKING MEMBERS:
Presidente - 2578619 - ANA HELONEIDA DE ARAUJO MORAIS
Interno - 2195251 - HUGO ALEXANDRE DE OLIVEIRA ROCHA
Externa à Instituição - PATRICIA BATISTA BARRA MEDEIROS BARBOSA - UERN