ROS and RNS modulation: the main antimicrobial, anticancer, antidiabetic, and antineurodegenerative mechanisms of metal or metal oxide nanoparticles

Severe side effects of chemotherapeutic and anti-diabetic drugs for cancer cells and type ۲ diabetes (T۲D) type and emerging drug resistance in pathogenic microorganisms, specifically bacteria, are the main barriers to achieving desired therapeutic results. Various antimicrobial and anticancer functions involve damaging cell membranes by direct contact with metal or metal oxide nanoparticles (NPs), inhibition of biofilm, formation of free radicals and nonradicals of reactive oxygen species (ROS) and reactive nitrogen species (RNS), inducing host immune responses, and denaturation biological macromolecules such as nucleic acids and protein have been found for metal or metal oxide NPs. The major one is the production of ROS, including peroxides (*O۲−۲), superoxide (*O۲−), hydroperoxyl (HO۲*), hydroxyl radical (HO*), and singlet oxygen (۱O۲*), as well as RNS such as peroxynitrite (ONOO−) and nitric oxide (NO*) under the oxidative stress via release of metal ions from NPs. Oxidative stress can result from the elevation of ROS more than the buffering capacity. ROS and RNS can cause lipid peroxidation, oxidative protein carbonylation, and inactivation of specific enzymes. This review shows that controlling the dose of ROS and specific targeting is for achieving promising anticancer and antimicrobial results in physiological conditions.