Table 1 Main reactive oxygen species (ROS) and reactive nitrogen species (RNS) induced by UVA and/or UVB radiation significantly affect skin cells' functioning
From: Natural protection against oxidative stress in human skin melanocytes
Reactive species | Type | Half-life | Primary targets in skin cells | Main sources of production |
|---|---|---|---|---|
Superoxide anion radical (O₂•⁻) | ROS (free radical) | microseconds to milliseconds | Lipids, proteins, DNA (indirectly via other ROS) | mitochondrial respiratory chain (complex I and III), NADPH oxidase, xanthine oxidase, melanin synthesis, inflammation, UVA/UVB radiation, smoking, air pollution, psychological stress 201 |
Hydrogen peroxide (H₂O₂) | ROS (non-radical) | seconds to minutes | Proteins, lipids, DNA | mitochondria, peroxisomes, xanthine oxidase, inflammation, UVA/UVB radiation, other skin cells transfer, and environmental pollution 202 |
Hydroxyl radical (•OH) | ROS (free radical) | extremely short (~10⁻⁹ s) | Lipids, proteins, DNA (strong oxidative damage) | Fenton reaction (Fe²⁺ + H₂O₂), ionizing radiation, inflammation, UVA/UVB radiation 203 |
Singlet oxygen (¹O₂) | ROS (non-radical) | microseconds (10−6 to 10−5 s) | Lipids, proteins, DNA | peroxisomes, UVA radiation, photosensitization 204 |
Nitric oxide (NO•) | RNS (free radical) | milliseconds to seconds | Proteins, lipids, signaling molecules | enzymatic synthesis, inflammation, UVA radiation, smoking, environmental pollution, and biological decay 205 |
Peroxynitrite (ONOO⁻) | RNS (non-radical) | milliseconds | Proteins, lipids, DNA (oxidation and nitration) | reaction of NO• with O₂•⁻, inflammation, UVB radiation, smoking, and environmental pollution 206 |
Nitrogen dioxide radical (NO₂•) | RNS (free radical) | milliseconds | Proteins, lipids | metabolism involving nitrates and nitrites, photolysis, UVA/UVB radiation, air pollution, smoking 207 |
