Free radical and oxygen toxicity Flashcards
What is oxygen toxicity?
the overall toxic effect of oxidative free radical species at cellular level
What is a free radical?
any species capable of independent existence that contains one or more unpaired electrons
What are reactive oxidative species?
a collective name for oxygen centered radicals and some non-radical derivatives of oxygen
What is oxidative stress?
the overall effect of oxygen species in causing tissue injury due to imbalance of free radicals and antioxidants in the body
Mention some cellular sources of free radicals
DNA peroxisomes cytoplasm lysosome nucleus mitochondria ER(potential source)
Some other internal sources of free radicals apart from those in the cell
phagocytes xanthine oxidase rxns involving iron and other transition metals exercise inflammation
Some externally generated sources of free radicals are
smoking radiation uv light ozone certain drugs
What happens when free radicals snare an electron from a neighboring molecule?
it makes that molecule a free radical and sets off a chain reaction that wrecks havoc on cells
What is the basis of formation for free radicals?
oxygen
What can cause the proliferation of free radicals?
a lack of antioxidants in diet
inability of the body to produce them
5 examples of free radicals
trichloromethyl CCl3* superoxide O3* hydroxyl OH* thyil RS* peroxyl RO2*
What does reactivity of a free radical depend on?
type of radical
what the radical is presented with
What does reactivity of a free radical depend on?
type of radical
what the radical is presented with
What happens when 2 free radicals meet?
they can join and form a covalent bond
What happens when a free radical reacts with a non-radical?
a free radical chain reaction results and a new radicals are formed
What starts lipid peroxidation atherosclerosis?
attacks of free radicals on membranes or lipoproteins
Attack of free radicals on DNA cause
mutation
What are some mechanisms of free radical toxicity?
lipid peroxidation
DNA damage
protein oxidation
What are the 4 processes of lipid peroxidation?
- Initiation
- Propagation
- Accumulation
- Cell death
What usually initiates peroxidation?
attack of any free radical species capable abstracting hydrogen ion from a polysaturated fatty acid side-chain in a membrane creating a carbon radical
What propagates lipid peroxidation?
the carbon radical reacts fast with oxygen resulting in a fatty acid chain peroxyl radical which can attack side chains
How is DNA destruction caused?
hydroxyl radicals generated close to DNA attack the purine and pyrimidine bases and cause mutations
What is an antioxidant?
a molecule stable enough to donate an electron to a rampaging free radical to neutralize it and reduce its capacity to damage
