Theories of Ageing: Antioxidants, polyphenols, oxidative stress. 02/04 Flashcards
Summarize the random damage theory of ageing
Aging is occurs because of organisms inability to withstand stochastic damage such as radiation and ROS. Ageing is therefore due to accumulation of ‘wear and tear’ due to random damage caused by oxygen free radicals and protein damage from glycosylation.
What is the Kirkwood 2005 study, and how does it support random damage theory?
The Kirkwood study shows that genetically identical wild type c-elegans worms raised in the same environments have a spread of lifespans from 3-31 days. Since environment and genes are constant, this suggests that some random factor has occurred.
What are the 6 main sources of reactive oxygen species?
- Mitochondrial metabolism
- The environment: radiation, pollution, UV light
3, Lipid peroxidation - Infection & inflammation: neutrophil bursts produced by NOX2 to kill pathogens
- Degradation of neurotransmitters
- Degrading dietary toxins
What is an antioxidant?
Any substance which, at low concentrations, significantly reduces oxidation of substrates. They can do so by inhibiting oxidation of the molecule, or by using electrons to neutralize the reactive oxygen species. They may be endogenous or exogenous.
List three endogenous enzyme antioxidants
Glutathione
Superoxide dsymutase
Catalase
These can neutralize thousands of ROS per second
List three exogenous antioxidants
Vitamin C
Vitamin E
Elements such as selenium which is required by glutathione, or Zn for SOD
List three endogenous non-enzyme antioxidants
Uric acid
Bilirubin
Albumin
- These are not as effective, as they can only neutralize one ROS
Why are an excess of antioxidant supplements harmful?
Antioxidants do not specifically target mitochondrial ROS, which is the root of the problem.
There is an optimum level of ROS. ROS are needed by White blood cells to fight infection, relaxes smooth muscle cells & increase intracellular signalling.
They can also increase ROS. Iron + Vit C = hydroxyl radical.
