Figure 1.

Formation of arachidonic acid hydroperoxides. Abstraction of the bis-allylic hydrogen leads to the attack of oxygen to either of two positions and the formation of arachidonic acid peroxyl radical (LOO•). The peroxyradical (5-20:4-OO•) is converted to arachidonic acid hydroperoxides (5-20:4-OOH) and propagates the reaction as the peroxyl radical abstracts a second hydrogen atom from the polyunsaturated fatty acid (PUFA). On the other hand, the peroxyradical (9-20:4-OO•) shows a tendency to generate its corresponding endoperoxide rather than arachidonic acid hydroperoxide (9-20:4-OOH).