Banca de QUALIFICAÇÃO: MARTA ANGELO DOS SANTOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARTA ANGELO DOS SANTOS
DATE: 28/08/2025
TIME: 13:00
LOCAL: Google Meet
TITLE:

Isolation, characterization, and evaluation of the insecticidal activity of lectin from the leaves of
Alternanthera Brasiliana against Tribolium Castaneum

KEY WORDS:

Letin; T.castaneum; Bioinsecticide

PAGES: 80
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

Lectins are proteins that exhibit a wide range of biological activities, including antibacterial,
antifungal, insecticidal, anti-inflammatory, antitumor, and wound-healing effects. Alternanthera
brasiliana, commonly referred to as penicillin or terramycin, is a medicinal plant native to Brazil,
recognized for its analgesic, anti-inflammatory, antitumor, and healing properties.This study aimed
to identify, isolate, and characterize a lectin extracted from the leaves of A. brasiliana as well as to
evaluate its insecticidal activity against Tribolium castaneum adults. Dried leaves were ground and
extracted in 50 mM Tris-HCl buffer (pH 8.0) for 16 hours under constant agitation. The extract was
filtered and subjected to hemagglutination activity (HA) assays, protein quantification, and inhibition
assays with various carbohydrates, followed by ammonium sulfate fractionation. The fraction
exhibiting the highest specific activity was further purified using CM-Sepharose chromatography
and a chitin column. The purity of the lectin was confirmed by 12% SDS-PAGE. The effect of
temperature, pH and ionic conditions on HA were assessed. Insecticidal activity was evaluated
based on adult mortality, nutritional parameters, and eggs hatching of T. castaneum, as well as the
biochemical profile of the treated insects. The extract exhibited an HA titer of 8 and was inhibited
by glucose, fructose and mannose. The isolated lectin (0.191 mg/mL) with a molecular weight of
13.45 kDa, was considered thermostable, retaining activity in the presence of Ca2+ and Mg2+ ions,
and demonstrating greater activity at pH 8.0. The A. brasiliana lectin caused 100% mortality of the
T. castaneum, in addition to exhibiting deterrent and anti-nutritional effects. It significantly impacted
reproduction, and interfered with the metabolism of proteins, cholesterol, triglycerides, and
carbohydrates. These findings highlight its potential for application in the biological control of T.
castaneum.

COMMITTEE MEMBERS:
Externo(a) à Instituição - ADRIANA DE LIMA MENDONCA - Tiradentes
Interno(a) - 426640 - FABIANE CAXICO DE ABREU GALDINO
Presidente - 2089586 - FRANCIS SOARES GOMES
Externo(a) ao Programa - 1653558 - LUCIANO APARECIDO MEIRELES GRILLO - nullInterno(a) - 1294906 - RUTH RUFINO DO NASCIMENTO