title: Oxidative stress generation of silver nanoparticles in three bacterial genera and its relationship with the antimicrobial activity.
abstract: Oxidative stress is a condition caused by the high intracellular concentrations of reactive oxygen species (ROS) that includes superoxide anion radicals, hydroxyl radicals and hydrogen peroxide. Nanoparticles could cause rapid generation of free radicals by redox reactions. ROS can react directly with membrane lipids, proteins and DNA and are normally scavenged by antioxidants that are capable of neutralizing; however, elevated concentrations of ROS in bacterial cells can result in oxidative stress. The aim of this work was contribute to the knowledge of action mechanism of silver nanoparticles (Ag-NPs) and their relation to the generation of oxidative stress in bacteria. We demonstrated that Ag-NPs generated oxidative stress in Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa mediated by the increment of ROS and this increase correlated with a better antimicrobial activity. On the other hand, we showed that the oxidative stress caused by the Ag-NPs biosynthesized was associated to a variation in the level of reactive nitrogen intermediates (RNI). Oxidative stress in bacteria can result from disruption of the electronic transport chain due to the high affinity of Ag-NPs for the cell membrane. This imbalance in the oxidative stress was evidentiated by a macromolecular oxidation at level of DNA, lipids and proteins in E. coli exposed to Ag-NPs. The formation of ROS and RNI by Ag-NPs may also be considered to explain the bacterial death.
authors.affiliation: Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina; Dto. Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
authors.forename: M A
authors.initials: MA
authors.lastname: Quinteros
authors.affiliation: Dto. Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
authors.forename: V
authors.initials: V
authors.lastname: Cano Aristizábal
authors.affiliation: CITSE, INBIONATEC, CONICET, Universidad Nacional de Santiago del Estero, RN 9, Km 1125, 4206 Santiago del Estero, Argentina.
authors.forename: P R
authors.initials: PR
authors.lastname: Dalmasso
authors.affiliation: Instituto Multidisciplinario de Biología Vegetal (IMBIV), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina; Cátedra de Microbiología, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Argentina.
authors.forename: M G
authors.initials: MG
authors.lastname: Paraje
authors.affiliation: Dto. Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina; Unidad de Tecnología Farmacéutica (UNITEFA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina. Electronic address: plpaez@fcq.unc.edu.ar.
authors.forename: P L
authors.initials: PL
authors.lastname: Páez
mesh_terms: D000900:Anti-Bacterial Agents / Q000633:toxicity*; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D053768:Metal Nanoparticles / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012834:Silver / Q000633:toxicity*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D017382:Reactive Oxygen Species; D012834:Silver
keywords: Antimicrobial activity; Bacteria; Biosynthesis; Oxidative stress; Silver nanoparticles