Banca de DEFESA: ALESSANDRA MARINHO MIRANDA LUCENA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALESSANDRA MARINHO MIRANDA LUCENA
DATE: 04/12/2024
TIME: 14:00
LOCAL: Videoconferência - Link para acesso: https://meet.google.com/vya-nftp-chh
TITLE:

ANTIOXIDANT ACTION AND NEUROPROTECTIVE EFFECT OF SULFATED POLYSACCHARIDES

KEY WORDS:

Seaweed, Polysaccharides, Oxidative stress, Neurodegeneration

PAGES: 124
BIG AREA: Ciências Biológicas
AREA: Bioquímica
SUMMARY:

Neurodegenerative diseases are the result of multifactorial biological mechanisms, involving both exogenous and endogenous causes. Due to the increase in life expectancy and the predicted growth of dementia conditions, there is a growing concern in the search for more effective prevention and treatment for neurodegeneration. Oxidative stress has been shown to be an important factor in the development and progression of these diseases, due to intrinsic characteristics of nervous tissue (e.g., low regenerative capacity and high energy demand). Seaweeds are sources of various bioactive molecules, especially sulfated polysaccharides (SP). These compounds are important for the maintenance and survival of sea weeds and have significant biological activities, such as antioxidant and anti-inflammatory. These properties can be useful in the treatment of neurodegenerative diseases. Seaweeds SP have shown promise as an alternative for neuroprotection. Nine species of seaweed have been identified whose SPs exhibit antioxidant action under different conditions. Forty-four sulfated polysaccharides rich fractions (PRF) were obtained. These PRF were evaluated for their cyto- toxicity in Neuro-2A cells at different concentrations (0.1, 0.25, 0.5, or 1 mg/mL). From each PRF, two concentrations were selected, one higher and one lower, which showed MTT reduction values equal to or greater than 80%. They were analyzed for their ability to protect against oxidative damage caused by hydrogen peroxide. To select the PRF that would be evaluated for the possible protection mechanisms employed, the results of yield parameters, cytotoxic effect, and neuroprotective potential in cell culture were considered to construct a Score. The possible mechanisms involved were analyzed by determining the hydrogen peroxide scavenging potential and the effect on the expression of genes in the antioxidant pathway (Keap1, Nrf2, Sod1, Cat, Gpx, Hmox1, Gclc, Gclm) and the subunits of the NFκB transcription factor (Nfkb1 and Rela). Additionally, the antioxidant protection capacity was evaluated in an in vivo model (Zebrafish). Forty-two PRF did not show cytotoxic effects against Neuro-2A cells at at least one of the evaluated concentrations. All evaluated seaweeds had PRF that protected Neuro-2A cells from oxidative damage induced by hydrogen peroxide. Furthermore, through the Score, it was possible to observe that brown seaweed had the best results. Based on these data, four PRF (DJ 1.2, SF 0.5, SS 1.3, and DM 1.0) were selected for the evaluation of the possible mechanisms involved. The data obtained here demonstrate that the mechanisms used by these samples range from direct action on oxidant molecules to the modulation of endogenous antioxidant mechanisms, promoting an increase in the expression of genes related to the translation of antioxidant enzymes and a reduction in the expression of genes related to a pro-inflammatory and pro-oxidant response. Additionally, these polysaccharides were able to promote protection against oxidative stress in an in vivo model. These data are important for the development of future evaluations of these molecules, as they provided knowledge about their potential neuroprotective effect and antioxidant behavior in more complex organisms, thus guiding the possible mechanisms employed.

COMMITTEE MEMBERS:
Externo à Instituição - FAUSTO PIERDONA GUZEN - UERN
Interno - 2195251 - HUGO ALEXANDRE DE OLIVEIRA ROCHA
Interna - 1453487 - KATIA CASTANHO SCORTECCI
Externo à Instituição - PABLO DE CASTRO SANTOS - UERN
Presidente - 2962496 - RAFAEL BARROS GOMES DA CAMARA
Externo à Instituição - ÉDER GALINARI FERREIRA - UFOP