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Advisor(s)
Abstract(s)
As quinoxalinas são compostos heterocíclicos que têm, entre outras, capacidades
antimicrobianas, inclusivamente contra bactérias resistentes aos antimicrobianos
convencionais. Os mecanismos pelos quais estes compostos exercem a sua atividade ainda
não está completamente esclarecido. O objetivo do presente estudo é avaliar o efeito redox
em sinergismo/antagonismo com as quinoxalinas em modelos de bactérias com e sem
resistências a antimicrobianos.
No que se refere aos compostos foram utilizados a quinoxalina 1,4-dióxido (QNX),
2-metil-3-benzilquinoxalina-1,4-dióxido (2M3BQNX), 2-metilquinoxalina-1,4-dióxido
(2MQNX) e a 2-amino-3-cianoquinoxalina-1,4-dióxido (2A3CQNX). Quanto aos modelos
procariotas, foram utilizados a Salmonella enterica, Klebsiella pneumoniae, Enterococcus
faecalis, Staphylococcus saprophyticus, Enterobacter aerogenes, Enterobacter cloacae,
Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus ATCC
43300, Escherichia coli TEM 201 e Escherichia coli TEM 180.
Nos compostos químicos em que se verificou a Concentração Mínima Inibitória
(CMI), realizou-se o estudo do comportamento do crescimento bacteriano. Relativamente
ao estado redox, foi avaliado para cada estirpe sensível, através do rácio GSH/GSSG, nas
doses inibitórias e não inibitórias de cada composto.
Os resultados apresentam que todos os compostos testados, à exceção do 2M3BQNX,
têm atividade antimicrobiana na maioria das estirpes, excetuando a E. faecalis e a S.
saprophyticus. Os rácios GSH/GSSG apontam para o efeito oxidante em K. pneumoniae e S.
enterica e antioxidante na E. aerogenes.
A conclusão do estudo sugere que os compostos apresentam elevada capacidade
antibacteriana e influência no equilíbrio redox das bactérias, podendo contribuir para o
esclarecimento do mecanismo de ação dos derivados das quinoxalinas 1-4 dióxido, nas
bactérias.
The quinoxalines are heterocyclic compounds having antimicrobial capacity even against bacteria resistant to the conventional antibiotics. The mechanisms by which these compounds exert their activity is not completely understood. The aim of this study is to evaluate the redox effect in synergism / antagonism with quinoxalines in models of bacteria with and without resistance to antimicrobials. As regard the compounds were used the quinoxaline 1,4-dioxide (QNX), 2-methyl- 3-benzilquinoxalina-1,4-dioxide (2M3BQNX), 2-methylquinoxaline-1,4-dioxide (2MQNX) and 2-amino-3-cianoquinoxalina-1,4-dioxide (2A3CQNX). As regards prokaryotic models were used Salmonella enterica, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus saprophyticus, Enterobacter aerogenes, Enterobacter cloacae, Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus ATCC 43300, Escherichia coli TEM 201 and Escherichia coli TEM 180. In chemical compounds which saw the Minimum Inhibitory Concentration (MIC) was held to study the behavior of bacterial growth. For the redox state was evaluated for each sensitive strain, using the GSH / GSSG ratio, the inhibiting and non-inhibiting dose of each compound. The results show that all compounds tested, except for 2M3BQNX have antimicrobial activity in most strains, except for E. faecalis and S. saprophyticus. The GSH/GSSG ratios point to the oxidizing effect on K. pneumoniae and S. enterica in E. aerogenes and antioxidant. The conclusion suggests that the compounds have high antibacterial ability and influence on the redox balance of bacteria and may contribute to the elucidation of the mechanism of action of derivatives of quinoxalines 1-4 dioxide in bacteria.
The quinoxalines are heterocyclic compounds having antimicrobial capacity even against bacteria resistant to the conventional antibiotics. The mechanisms by which these compounds exert their activity is not completely understood. The aim of this study is to evaluate the redox effect in synergism / antagonism with quinoxalines in models of bacteria with and without resistance to antimicrobials. As regard the compounds were used the quinoxaline 1,4-dioxide (QNX), 2-methyl- 3-benzilquinoxalina-1,4-dioxide (2M3BQNX), 2-methylquinoxaline-1,4-dioxide (2MQNX) and 2-amino-3-cianoquinoxalina-1,4-dioxide (2A3CQNX). As regards prokaryotic models were used Salmonella enterica, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus saprophyticus, Enterobacter aerogenes, Enterobacter cloacae, Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus ATCC 43300, Escherichia coli TEM 201 and Escherichia coli TEM 180. In chemical compounds which saw the Minimum Inhibitory Concentration (MIC) was held to study the behavior of bacterial growth. For the redox state was evaluated for each sensitive strain, using the GSH / GSSG ratio, the inhibiting and non-inhibiting dose of each compound. The results show that all compounds tested, except for 2M3BQNX have antimicrobial activity in most strains, except for E. faecalis and S. saprophyticus. The GSH/GSSG ratios point to the oxidizing effect on K. pneumoniae and S. enterica in E. aerogenes and antioxidant. The conclusion suggests that the compounds have high antibacterial ability and influence on the redox balance of bacteria and may contribute to the elucidation of the mechanism of action of derivatives of quinoxalines 1-4 dioxide in bacteria.
Description
Keywords
Quinoxalinas N,N-dióxido Métodos de suscetibilidade Antimicrobiana Atividade antimicrobiana Curvas de crescimento Stress oxidativo Quinoxalines N, N-dioxide Methods of antimicrobial susceptibility Antimicrobial activity Growth curves Oxidative stress