Banca de QUALIFICAÇÃO: JORDAN KERVEN PATRÍCIO DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : JORDAN KERVEN PATRÍCIO DA SILVA
DATA : 12/10/2019
HORA: 14:00
LOCAL: Auditório do Química III
TÍTULO:

Development of a new methodology for detection of L-cysteine in aqueous médium based on its reaction with 2,3-dichloro-6,7-dinitroquinoxaline

PALAVRAS-CHAVES:

quinoxalin; 2,3-dicloroquinoxaline; organic synthesis; funcionalization; anticâncer activity; silver nanoparticles

PÁGINAS: 50
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Físico-Química Orgânica
RESUMO:

Amino acids are key species in several biological processes due their role as building block for the synthesis of proteins as well as other biological functions. L-cysteine is an essential proteic amino acid, and beside other functions, acts effectively in active site of enzymes and as glutathione precursor. Due its relevance, Cys became an interesting analyte for the development of selective chemosensors, especially to overcome the drawbacks associated to main methodologies for detection of Cys, which usually require laborious procedure, sophisticated instrumentation and considerable time of analysis. This work reports the use of 2,3-dichloro-,6-7dinitroquinoxaline (DCDNQX) as a functional chemosensor for detection of Cys in aqueous solution. DCDNQX was synthetized in good overall yield via a sequential three-step protocol. The methodology for Cys sensing is based on the nucleophilic aromatic substitution (SNAr) reactions of DCNQX, a highly activated substrate for this type of chemical transformation. It was verified by UV-Vis spectroscopy, that DCQNQX reacts selectively with Cys over other selected amino acids (tyrosine (Tyr), alanine (Ala), lysine (Lys), Histidine (His) and glutamic acid (Glu)) in DMF-H₂O 5:1 v/v solution in the presence of K₂CO₃. This behavior is justified by the high nucleophilicy of tiolate over phenols and amines in SNAr reactions. Selective sensing was based on the band at 275 nm that emerges in the reaction between DCDNQX and Cys after 20 minutes. At this moment, the products from reaction of DCQNQX and Cys are under characterization in attempt to understand the whole mechanisms involved in the detection of this relevant amino acid.

MEMBROS DA BANCA:
Presidente - 1803692 - FABRICIO GAVA MENEZES
Interna - 2140775 - LIVIA NUNES CAVALCANTI
Interna - 1569526 - RENATA MENDONÇA ARAUJO