Table 1.
Summary of the primary source of ROS
| Source of ROS | Response stimuli | Pathway complexes | Main ROS |
|---|---|---|---|
| Mitochondria | Oxidative metabolism | Electron transport chain, NADH | O2•− |
| NADPH oxidase | Inflammation | NAPDH | O2•− |
| Xanthine oxidase | Purine catabolism | O2 | O2•− |
| Nitric oxide synthase | Synaptic activity, inflammation, hypoxia | NADPH | NO, OONO |
| Peroxisomes | Lipid metabolism (β-oxidation) | NADH, NADPH, FADH2 | H2O2, O2•− |
| Cytochrome P450 | Clearance of various compounds (hormones, lipids, xenobiotics) | NADPH | O2•− |
| Lipoxygenases | Arachidonic Acid (PUFA) metabolism | O2 | O2•− |
| Exogenous stress | Direct peroxidation, increased NOS, DNA damage | UV, environmental toxins, drugs | O2•−, ONOO•−, H2O2 |