Banca de QUALIFICAÇÃO: JOICY RIBEIRO DOS SANTOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOICY RIBEIRO DOS SANTOS
DATE: 12/09/2025
TIME: 14:00
LOCAL: Videoconferência
TITLE:

CONJUGATION OF FUCOIDAN B FROM THE ALGA Spatoglossum schröederi WITH GALLIC ACID AND EVALUATION OF ITS ANTIOXIDANT ACTIVITY IN VITRO, IN CELLS (MURINE FIBROBLAST L929) AND IN VIVO (Danio rerio)

KEY WORDS:

Sulfated polysaccharides; fucans; brown seaweed; oxidative stress

PAGES: 100
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Oxidative stress is associated with a wide range of physiological dysfunctions and diseases. In this context, there is growing scientific interest in identifying molecules capable of inhibiting the formation of reactive oxygen species (ROS), reducing their accumulation, or mitigating their harmful effects. Fucoidans, sulfated polysaccharides (PS) exclusively found in brown algae, exhibit various pharmacological properties, including anticoagulant, anti-inflammatory, and antioxidant activities, which can be enhanced through chemical modifications. In this study, fucoidan B from the brown alga Spatoglossum schröederi was isolated, chemically conjugated with gallic acid (GA), and evaluated for its antioxidant activity both in vitro and in vivo. The resulting derivative, named FucB-GA, was physicochemically characterized, showing a molecular weight of 22.8 kDa, 3% phenolic content, and no protein contamination. FT-IR and ¹H NMR analyses confirmed the insertion of GA into the polymeric chain, accompanied by changes in crystallinity and thermal stability. In vitro assays revealed that, although the samples did not chelate Fe²⁺, FucB-GA exhibited a higher Cu²⁺ chelating capacity than FucB. Regarding radical scavenging, no significant differences were observed for H₂O₂; however, for superoxide radicals, FucB-GA reached an inhibition capacity of 91.96%, compared to 80.51% for FucB. Moreover, FucB-GA showed markedly superior performance in the total antioxidant capacity assay (approximately three times higher) and reducing power (about four times greater). In cellular models, FucB-GA protected cells against H₂O₂-induced oxidative stress in both reparative and concomitant conditions, significantly reducing cell death. In the Danio rerio animal model, the compound increased embryo survival rates under oxidative stress and decreased intracellular ROS production. Altogether, the results demonstrate that the chemical modification of fucoidan enhanced its antioxidant properties, highlighting FucB-GA as a promising candidate molecule for future pharmacological applications.

COMMITTEE MEMBERS:
Interna - 2290234 - LUCIANA DUARTE MARTINS DA MATTA
Externo à Instituição - MOACIR FERNANDES DE QUEIROZ NETO - UFPB
Presidente - 2962496 - RAFAEL BARROS GOMES DA CAMARA