Banca de DEFESA: THUANNY MOURA DE SOUSA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : THUANNY MOURA DE SOUSA
DATE: 19/07/2024
TIME: 14:00
LOCAL: videoconferência
TITLE:

Ruthenium Nitrosyl Complexes: Synthesis, Characterization, Reactivity and action towards plasmid DNA

KEY WORDS:

Nitric Oxide; Nitrosyl Complexes; Ruthenium; Plasmid DNA

PAGES: 116
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Campos de Coordenação
SUMMARY:

Nitric oxide (NO) is a signaling molecule involved in several biological processes, including the regulation of blood pressure, neurotransmission, immunological responses, antibacterial activity and anticancer activity. For this reason, nitrosyl complexes have been investigated as NO donors in order to improve the biological applications of this molecule that depends on modulating the structure of the complexes to interact or act on potential molecular targets. In this context, this paper aims to develop new ruthenium nitrosyl complexes of the system [Ru(bpy)(L)(NO2)(NO)](PF6)2, where L are the ligands phen = 1,10'- phenanthroline, phendione = 1,10'-phenanthroline-5,6-dione and bpy = 2,2'-bipyridine, capable of acting as nitric oxide releasers in biological systems. The compounds were obtained from the cis-[Ru(bpy)(L)Cl2] precursor complexes in water and ethanol, with the addition of the ligand sodium nitrite in HTFA 4 mol.L -1 . Trough the infrared technique, in KBr pellets, the complexes exhibited vibrational modes at 1941 and 1944 cm1 associated with NO+ with phenanthroline and phendione, respectively, indicating the coordination of the nitric oxide ligand. Using the UV-vis technique, in acetonitrile, it was possible to identify intraligand bands of π → π* character in the ultraviolet region as well as charges transfer transitions from ruthenium to polypyridine ligands around 450 nm. The cyclic voltammograms obtained in 0.1 mol.L-1 NaTFA and pH = 3.5 showed a half-wave potential of 122 mV for the complex with phenanthroline and 133 mV with phendione, both referring to the NO+/0 redox couple. Regarding UV-Vis reactivity, the complexes showed evidence of NO release in the presence of glutathione and cysteine due to the generation of intermediate products at 450 and 380 nm as well as the formation of the aqueous complex at 450 nm. Meanwhile, in square wave voltammetry, the reaction of the compounds with glutathione, histidine and methionine showed qualitative signs of NO release, due to the appearance of processes in the range of 100-150 and 500-700 mV characteristic of the redox pairs NO+/0 and Ru3+/2+, respectively. Finally, (pBR322) plasmid DNA cleavage tests revealed that in the dark the complexes do not exhibit activity even with up to 60 µM of the compounds. However, under blue LED irradiation (460 nm) and in the presence of glutathione, the complexes showed signs of cleavage, therefore altering their form I (supercoiled) structure between forms II (open circular) and forms III (linear form).

COMMITTEE MEMBERS:
Interno - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Externo ao Programa - 1715109 - DANIEL DE LIMA PONTES - UFRNPresidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externo à Instituição - FRANCISCO ADILSON MATOS SALES - IFCE
Externo ao Programa - 1945343 - FRANCISCO ORDELEI NASCIMENTO DA SILVA - nullExterno à Instituição - SÉRGIO XAVIER BARBOSA ARAÚJO - UFC