Banca de DEFESA: FLAVIA ROBERTA MONTEIRO DE SOUZA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FLAVIA ROBERTA MONTEIRO DE SOUZA
DATE: 23/08/2022
TIME: 08:00
LOCAL: Videoconferência - Link para acesso: https://meet.google.com/seq-ohdy-qas
TITLE:

SULFATED POLYSACCHARIDES OF Gracilaria birdiae, EXTRACT OF LEAVES of Baccharis trimera AND BLENDS CONSTITUTED BY THESE AGENTS: EVALUATION OF ANTIOXIDANT ACTIVITY AND THE CAPACITY OF INHIBITING LIPID ACCUMULATION

KEY WORDS:

Obesity, oxidative stress, sulfated polysaccharides, phenolic compounds, Caenorhabditis elegans.

PAGES: 180
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUBÁREA: Química de Macromoléculas
SPECIALTY: Glicídeos
SUMMARY:

Obesity, characterized by excess body fat, is an inflammatory disease. Several factors seen in obese people, including chronic inflammation, can induce oxidative stress in these people. Within this context, antioxidants of natural origin are pointed out as promising agents to be incorporated in the treatment of obesity. The edible red algae Gracilaria birdiae synthesizes antioxidant sulfated polysaccharides. The Baccharis trimera plant is used in folk medicine for the treatment of obesity. Thus, the present study aimed to evaluate sulfated polysaccharides from the red alga G. birdiae (GB) and extracts from the leaves of B. trimera (BT), as well as the blends made from these products as antioxidants and inhibitors of lipid accumulation. In the case of blends, the objective was also to verify whether the blends made from these products could optimize such biological activities in vitro and in vivo. GB was obtained by proteolysis of the alga. BT was obtained by decoction. GB showed in vitro antioxidant capacity in five assays. GB was not cytotoxic and inhibited the differentiation of preadipocytes (3T3-L1), as well as decreased the accumulation of lipids in these cells. In studies with Caenorhabditis elegans, GB reduced the levels of reactive oxygen species (ROS) and increased the longevity of animals under stress conditions. In addition, it decreases the content of triglycerides. Phytochemical analysis of BT showed rutin, apigenin and 5-caffeoylquinic acid as the main components of BT. The data showed that BT is not toxic to 3T3 fibroblasts, nor to C. elegans. BT reduced the accumulation of lipids in worms submitted to diets rich or not in glucose. Furthermore, using RNA interference (RNAi), it was observed that BT depends on the transcription factor NHR-49 to exert its anti-obesity effect on worms. Through the formulation of blends, compounds with different concentrations of GB and BT were obtained. In most in vitro antioxidant tests, the blends GB:BT (50:50%) called GB50-BT50 and GB:BT (75:25%) (GB25-BT75) were more potent than GB and BT. ROS production in C. elegans was reduced mainly with GB50-BT50 and GB25-BT75 (5,0 mg/mL). The animals that showed the most significant reduction in fat inhibition were those treated with BT and GB25-BT75. Specifically for triglycerides, the greatest reduction was observed in animals treated with the GB25-BT75 blend. ROS quantification assays were also performed in knockdown animals for SKN-1 and DAF-16 transcription factors using RNAi and survival assay under oxidative stress conditions in skn-1(zu67) mutant animals. Still using RNAi, the mechanisms involved in the accumulation of lipids for the TUB-1 and NHR-49 transcription factors were evaluated. The results showed that the effects provided by the treatment with the blends in reducing oxidative stress were dependent on the transcription factor SKN-1. Regarding the inhibition of lipid accumulation, the main transcription factor involved was NHR-49. In view of the results presented, the potential antioxidant activity and inhibitor of the accumulation of lipids of GB and BT, separately, and the potential of the therapeutic action of these components when combined together in the form of blends were proved.

COMMITTEE MEMBERS:
Interno - 2195251 - HUGO ALEXANDRE DE OLIVEIRA ROCHA
Interno - 2962496 - RAFAEL BARROS GOMES DA CAMARA
Externo ao Programa - 1221519 - DÁRLIO INÁCIO ALVES TEIXEIRA - UFRNExterno à Instituição - ALEXANDRE COELHO SERQUIZ - UNI-RN
Externa à Instituição - HERYKA MYRNA MAIA RAMALHO - UnP