Reactive oxygen species (ROS)

Reactive oxygen species are oxygen-containing molecules such as superoxide, hydrogen peroxide, and hydroxyl radicals produced by multiple cellular sources, including mitochondrial respiration, NADPH oxidases, peroxisomes, and the immune respiratory burst. At low levels they act as signalling molecules regulating immunity and metabolism, but excess ROS damages lipids, proteins, and DNA. Chronic ROS accumulation contributes to mitochondrial decline, cellular senescence, and age-related diseases including cardiovascular and neurodegenerative disorders.