Singlet oxygen or transition metal ions generate ROS

(II).           RH     +   1O2 (singlet oxygen)                                 ROOH  

(III).         ROOH  +   Fe+2                             RO·   +    HO-   +   Fe+3

(IV).         ROOH  +   Fe+3                           ROO·    +    H+  +    Fe+2

 

RH = Polyunsaturated fatty acid (PUFA). ROOH = PUFA hydroperoxide.

RO· = Alkoxyl radical. ROO· = Peroxyl radical 


Fig. (4). Mechanism of linoleic acid peroxidation and reactive oxygen species (ROS) formation.