1. breakdown of lipid hydroperoxide termination reactions
a) Lipid peroxidation-chain reactions
- ROS
- other free radicals
- Fe 2+ or Cu 2+
R + LH ●
L + RH
lipid radicals
initiation reaction 1) 2)
L + O2
LOO
lipid peroxyl radicals 3)
+ LH
LOOH + L
lipid hydroperoxide
propagation 4)
LOOH
LO , LOO , aldehydes
breakdown of lipid hydroperoxide 5) 2L
2LO
2LOO
L - L
L - OO - L
LOOL + O2
termination reactions
b) Aldehydic end-products of lipid peroxidation HC O
H2C
malonyldialdehyde (MDA)
CH3
(CH2)n CH OH
4-OH-2,3-alkenals (HAKs)
In biological systems: n = OH-2,3-hexenal (HHE)
n = OH-2,3-nonenal (HNE)
n = OH-2,3-undecenal (HUE)
c) F2 - isoprostanes OH
CO2H I II
III IV
PGF2-like compounds I – IV are the four regio-isomers that have been shown to originate from free-radical initiated non-enzymatic peroxidation of arachidonic acid (20:4). From a chemical point of view any single regio-isomer is composed by 8 racemic diastereomers.