Antioxidants + Free Radicals Flashcards
What is a free radical?
Any molecular species existing with unpairs electrons in the atomic valence shell
What are sources of free radicals?
Endogenous:
- metabolism
- enzymatic oxidation
- systemic inflammation
- exercise
- obesity
Exogenous
- radiation
- smoking
- carcinogens in food
- air and water pollution
- pesticides
What is antioxidant capacity?
The synergistic work between endogenous and exogenous, enzymatic and non-enzymatic antioxidant systems in keeping free radicals in equilibrium
What components are involved in to Non-Enzymatic Antioxidant System?
- Vitamin E
- Phytochemicals
- Vitamin C
- Glutathione
- Uric Acid
- Melatonin
How does Vitamin E work as an antioxidant?
Vitamin E removes free radical intermediates and prevents the propagation of reactions
Produces oxidised alpha tocopherol radicals that reduce other antioxidant to their reduced form to be recycles
What role do phytochemicals play in the antioxidant system?
Phytochemicals are mild electron donors
Also signal gene transcription of the enzymatic system
What role does vitamin C play in the antioxidant system?
Reduces and neutralizes ROS
What does glutathione do in the antioxidant system?
Not an enzyme
Most important cellular antioxidant
Maintains redox status in the cells
What role does uric acid play in the antioxidant system?
50% of the antioxidant capacity of plasma
What are the enzymes involved in the Enzymatic Antioxidant System?
- Superoxide dismutase (SOD)
- Catalase
- Glutathione enzyme
- Nrf2
What is the role of superoxide dismutase? What are the 3 varieties and their cofactors?
converts superoxide into hydrogen peroxide
SOD1: copper and zinc dependent
SOD2: manganese dependent
SOD3: iron dependent
What is the role of catalase?
Converts hydrogen peroxide to water and oxygen in ever cell
What is Nrf2?
A transcription factor that signals the expression of genes for the antioxidant systems
Activated when there is an increase in free radicals in the cell
When activated it moves into the nucleus and binds to the antioxidant response element and promotes gene expression
