Reactive Oxygen Species Flashcards
1
Q
What is ROS?
A
chemically reactive radical that contians O2
2
Q
What is a radical?
A
moelcule with highly reactive unpaired electron in outer orbital
3
Q
What are the examples of ROS?
A
- superoxide (O2)
- hydrogen peroxide (H2O2)
- hydroxyl radical (OH) -> most toxic form
4
Q
What are the 2 reactions of ROS formation?
A
- fenton reaction: Fe2+ + H2O2 -> Fe3+ + OH (radical) + OH-
- Harder-Weiss reaction: O2 + H2O2 -> O2 + H2O + OH (radical)
5
Q
ROS are produced where as a defense against pathogens?
A
neutrophils
6
Q
How is ROS a toxic effect using lipid peroxidation?
A
- unsaturated fatty acid chains on membranes attacked by hydroxyl radical
- radical reacts with O2 to yield peroxyl radical
7
Q
What happens when ROS damages the membrane?
A
- membrane rigidity and fluidity
- activity of membrane receptors and pumps
8
Q
What are the enzymes used as cellular defense in ROS?
A
- superoxide dismutase (Cu/Zn/Mn): converts superoxide anion to hydrogen peroxide
- catalase (Fe): converts hydrogen peroxide to water and O2 in peroxisomes
- glutathione peroxidase (Se): removes hydrogen peroxide and lipid peroxide
9
Q
What antioxidants/vitamins defend against ROS?
A
- foods rich in vitamins C,D,E and beta-carotene
- vitamin C: reduces superoxide and lipid peroxyl radicals
- vitamin E: reduces lipid hydroperoxyl radicals
10
Q
What polyphenols defend against ROS?
A
green tea, berries, resveratrol
11
Q
What are the diseases involving ROS?
A
- cardio: ischemia, myocardio reperfusion
- chronic inflammation: diabetes, rheumatoid arthritis, lupus
- cancer: renal, breast, lung
- neurological: alzheimers, parkinsons, ALS
- sensory impairment: ocular disease, hearing loss
- infectious: hepatitis, HIV, influenza
