Oxidative stress and antioxidants Flashcards
What are the reactive oxygen species found in humans?
Superoxide, hydroxyl radical and hydrogen peroxide
What are the reactive nitrogen species found in humans?
Nitric ocide and peroxynitrite
What is used as a marker of oxidative damage in cells?
The amount of 8-oxo-dG present
What affects can ROS have on DNA?
Modify bases causing mispairing
Can cause strand breaks
What is the effect of ROS on proteins? Specifically cysteine residues.
Inappropriate disulphide bond formation
What happens when lipids react with free radicals?
Lipid radicals are formed which can then react with O2 to form a lipid peroxyl radical leading to a chain reaction
Why can the electron transport chain be a source of ROS?
Occasionally electrons can escape and react with O2 to form a superoxide
Nitric oxide synthase forms a RNS from arginine normally within the body why?
The release of RNS helps to destroy invading bacteria
What is the role of the enzyme catalase?
To convert hydrogen peroxide to water and oxygen
Superoxide dimutase is a primary cellular defence against what?
It converts superoxide to hydrogen peroxide
What is the role of glutathione reductase?
It converts NADPH and GSSG to NADP and GSH
GSH reacts with hydrogen peroxide as a part of the cellular defence against ROS’s. What enzyme catalyse this reaction?
Glutathione peroxidase
Lipid radicals can be converted back to lipids by Vitamin E. Vitamin E however becomes oxidised. Which vitamin reduces oxidised vitamin E?
Vitamin C
Heinz bodies are a clinical sign of ……. deficiency
G-6-P DH deficiency
What is ischaemia reperfusion injury?
It is the reintroduction of oxygenated blood to an area that has suffered ischaemia. The reintroduction can do harm as ROS can be produced and won’t be able to be removed due to the loss of antioxidants during ischaemia.
What is paracetamol converted to when it is present in high levels?
N-acetyl-p-benzoquinoneamine or NADPQI
NADPQI is produced from paracetamol. It is toxic why?
Directly because it causes oxidative damage to cells but indirectly as it depletes glutathione levels furthering the extent of oxidative damage.
Acetylcysteine treatment is used for what?
It works by replenishing glutathione levels in paracetamol overdose
Where does paracetamol detoxification take place?
The liver
What are free radicals?
An atom or molecule w/ one or more unpaired electron
In the treatment of paracetamol overdose, which drug can be administered to help maintain or replenish depleted glutathione levels?
Acetylcysteine
