Table 1 Equations
Oxygen radical generation | |||
   NADPH oxidase: | 2O2 + NADPH | → | 2O2•- (superoxide) + NADPH+ + H+ |
   Spontaneous conversion: | 2O2•- + 2H+ | → | [2HO2• (hydroperoxyl radical)] → O2 + H2O2 |
   Superoxide dismutase: | 2O2•- + 2H+ | → | O2 + H2O2 |
   Myeloperoxidase: | Cl- + H2O2 | → | OCl- (oxidised halide) + H2O |
Reactive oxygen species secondary products | |||
|  | H2O2 + Fe2+ | → | OH- + OH• (hydroxyl radical) + Fe3+ |
|  | Fe3+ + O2•- | → | O2 + Fe2+ |
|  | O2•- + HOCl | → | O2•- + OH• + Cl- |
|  | H2O2 + OCl- | → | 1O2 (singlet oxygen) + H2O + Cl- |
|  | NH3 + HOCl | → | NH2Cl (chloramine) + H2O |
|  | R-CHNH2-COOH + HOCl → | R-CHNHCl-COOH + H2O → | R-CHO + CO2 + NH4+ + Cl- |
| Â | (amino acids) | (chloramines) | (aldehydes) |
Nitrogen radical generation and secondary reactions | |||
   Nitric oxide synthetase: | arginine + O2 + NADPH | → | NO• + citrulline + NADP+ |
|  | NO• + O2•- | → | ONOO- (peroxynitrite) |
|  | ONOO- + H+ | → | ONOOH (peroxynitrous acid) |
|  | ONOOH (peroxynitrous acid) | → | NO3- (nitrate ion) |
|  | ONOOH | → | NO2+ (nitronium ion) |
|  | ONOOH | → | NO2• (nitrogen dioxide radical) |
|  | ONOOH | → | OH- |
|  | ONOOH | → | OH• (hydroxyl radical) |
Lipid peroxidation | |||
|  | LH + Radical• | → | L• + RH |
|  | L• + O2 | → | LOO• (lipid peroxyl radical) |
|  | LH + LOO• | → | L• + LOOH (leading to lipid propagation) |
|  | LOO• + TocOH (α-tocopherol) | → | LOOH + TocO• (chain termination) |