Damaging reactions of free radicals on Lipids. Free radicals can cause significant damage to various vital biomolecules in cells, including lipids, proteins, carbohydrates, and nucleic acids.
Here's a detailed explanation of how these damaging reactions occur:
Lipid Peroxidation Process:
1. Initiation:
The process begins when a free radical abstracts a hydrogen atom from a polyunsaturated fatty acid (PUFA) in a lipid membrane, creating a lipid radical. This is highly reactive.
2. Propagation:
The lipid radical reacts with molecular oxygen, forming a lipid peroxyl radical.
This radical is capable of stealing a hydrogen atom from another lipid molecule, perpetuating a chain reaction that produces more lipid radicals.
3. Termination:
Eventually, two radicals may react with each other to form a stable product, ending the chain reaction. However, before termination, numerous lipid molecules can be damaged.
Consequences:
Formation of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), toxic compounds that can form adducts with DNA and proteins, further impairing their function.
Disruption of membrane integrity and fluidity, impairing cell functions such as signal transduction and transport mechanisms.