Banca de QUALIFICAÇÃO: THAYNÁ FERREIRA DE MENDONÇA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : THAYNÁ FERREIRA DE MENDONÇA
DATE: 31/01/2024
TIME: 14:00
LOCAL: Auditório do Departamento de Química
TITLE:

STUDY OF GLYCEMIC CONTROL THROUGH THE USE OF OXIDOVANADIUM(4+) COMPLEXES WITH AIM TO MINIMIZE THE PHENOMENON OF PERIPHERAL RESISTANCE TO INSULIN CAUSED BY TREATMENT WITH DEXAMETHASONE

KEY WORDS:

Dexamethasone, peripheral insulin resistance, oxovanadium(4+), antidiabetic compound

PAGES: 103
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Química Bio-Inorgânica
SUMMARY:

Diabetes is a global problem responsible for more than 6 million deaths a year, with peripheral insulin resistance (PIR) being a determining factor in these figures. During the COVID-19 pandemic, several patients developed PIR due to the treatment of inflammatory cascades using the glucocorticoid dexamethasone. In order to investigate the potential of oxovanadium(4+) compounds in reducing the factors that trigger the phenomenon of peripheral insulin resistance through the use of dexamethasone, a new vanadium complex was synthesized and characterized in this work. The synthesis of the oxovanadium(4+) compound was carried out in three stages, the first being the formation of sodium glycinate in approximately 24 hours, the analysis of which via infrared spectroscopy showed C=O and C-O bands at 1556 and 1271 cm^-1, respectively. The broad acid band was suppressed, leaving only the NH₂ band at ν 3427 cm^-1, which corroborates the formation of sodium glycinate. Subsequently, the second reaction stage consisted of the formation of sodium ascorbate, which showed C=O, C-O and C=C bands at 1703, 1577 and 1124 cm^-1, respectively, in the infrared spectrum. The -OH band of the lactone was suppressed at ν 3408 cm^-1, which corroborates the formation of ascorbate. The last stage was the synthesis of the oxovanadium(4+) complex, using one mole of each ligand previously deprotonated in methanolic medium, with controlled addition of oxovanadium sulphate. The reaction was maintained for 24 hours, and after the reaction time the solvent was evaporated, and the complex was washed and characterized. The electronic absorption spectrum showed an absorption maximum at 783 nm, which was photostable for up to 48 hours, without suppression of the V(4+) band at the end of the test, giving the complex stability against V⁴⁺/V⁵⁺ oxidation. The infrared spectrum of the complex showed C=O and C-O bands at 1504 and 1313 cm^-1, respectively. NH₂ and OH bands appeared at 3379 and ν 3209 cm^-1, from the glycinate anion; as well as C=O and C-O bands at 1789 and 1103 cm^-1, respectively. The appearance of C=C bands was also observed at 1622 cm^-1, a broad OH band, and the characteristic band of the oxovanadium(4+) group at 966 cm^-1. The voltammogram of the complex showed an anodic V(4+)/V(5+) oxidation peak close to the VOSO₄ peak region in phosphate buffer solution pH = 7, indicating the presence of the VO²⁺ species in the complex formed in aqueous media. The ⁵¹V NMR showed no peaks in the complex, confirming the absence of the V(5+) and V(3+) species. The EPR of the complex confirmed the presence of V(4+), with the presence of eight hyperfine lines. At the same time, the TG curve showed the first event near 100 ºC, referring to the loss of water molecules from hydration, with a mass loss of 5.47%. The second and third events are related to the degradation of the complex. The final residue corresponded to 19.70%, correlating with the formation of VO (20.00%).

COMMITTEE MEMBERS:
Interna - ***.823.784-** - BEATE SAEGESSER SANTOS - UFPE
Interno - JOAO RUFINO DE FREITAS FILHO
Externo ao Programa - 3022573 - JUCLEITON JOSE RUFINO DE FREITAS - nullPresidente - MONICA FREIRE BELIAN