Antimicrobial strategies centered around reactive oxygen species – bactericidal antibiotics, photodynamic therapy, and beyond

Abstract

Reactive oxygen species (ROS) can attack a diverse range of targets to exert antimicrobial activity, which accounts for their versatility in mediating host defense against a broad range of pathogens. Most ROS are formed by the partial reduction of molecular oxygen. Four major ROS are recognized comprising: superoxide (O2•−), hydrogen peroxide (H2O2), hydroxyl radical (•OH), and singlet oxygen (1O2), but they display very different kinetics and levels of activity. The effects of O2•− and H2O2 are less acute than those of •OH and 1O2, since the former are much less reactive and can be detoxified by endogenous antioxidants (both enzymatic and non-enzymatic) that are induced by oxidative stress. In contrast, no enzyme can detoxify •OH or 1O2, making them extremely toxic and acutely lethal. The present review will highlight the various methods of ROS formation and their mechanism of action. Antioxidant defenses against ROS in microbial cells and the use of ROS by antimicrobial host defense systems are covered. Antimicrobial approaches primarily utilizing ROS comprise both bactericidal antibiotics, and non-pharmacological methods such as photodynamic therapy, titanium dioxide photocatalysis, cold plasma and medicinal honey. A brief final section covers, reactive nitrogen species, and related therapeutics, such as acidified nitrite and nitric oxide releasing nanoparticles.

Systematic Approach to In-Depth Understanding of Photoelectrocatalytic Bacterial Inactivation Mechanisms by Tracking the Decomposed Building Blocks

“…34 The increased ROSs, such as 28,35,36 Thus, the SOD and CAT activities during bactericidal treatment were also monitored, and the results are shown in Figures 2b and 2c. For the PEC process, the decrease of both SOD and CAT activities was observed after 10 min of inactivation and continued thereafter.…”

Fotoinativação seletiva dos microorganismos: Escherichia coli e staphylococcus aureus

“…No mecanismo Tipo II ocorre a transferência de energia entre FS no estado T 1 e o oxigênio molecular, promovendo a formação de ) [9,123,124,126]. …”

“…Além disso, a dose de luz utilizada, o tipo de célula microbiana e o seu nível de oxigenação são parâmetros determinantes para a ação de aPDT [9,120,123,124,126].…”

“…Quando o FS é exposto à radiação em comprimento de onda apropriado, passa para o estado excitado levando a uma série de transferências moleculares de energia formando EROs [9].…”

“…Assim, a peroxidação de lipídeos afeta a estrutura e o funcionamento da membrana celular, diminuindo a sua fluidez e aumentando sua permeabilidade aos íons. Tal fato pode também proporcionar a inativação de receptores celulares e de enzimas localizadas na membrana citoplasmática [125].No mecanismo Tipo II ocorre a transferência de energia entre FS no estado T 1 e o oxigênio molecular, promovendo a formação de ) [9,123,124,126]. …”