The oxidized forms of vitamin C, for example, are relatively unreactive, and do not cause any cellular damage.
That's is quite a big statement, can you back this up with reference?
Its not that big a statement.
A radical reacting with non-radical always creates another radical,
so that such a chain reaction would only be ended when 2 radicals react with eachother,
which would make the body relatively saturated with radicals (as low saturation strongly inhibits the chance of 2 radicals reacting).
And that, of course, is undesirable.
Thats why there are antioxidants. These compounds are called anti-oxidants because
they can also end a specific radical chain reaction.
If they cannot, they are not anti-oxidants, but just another non-radical.
Thats why anti-oxidants usually produce less reactive compounds upon oxidation.
The (main) oxidized product of vitamin C is dehydroascorbic acid (DHvit.C) Leung K et al
which is transported into the cell by facilitative hexose transporters (GLUTs). Angulo C et al
, which is inhibited by flavonoids, which also inhibit uptake of vit.C. Park JB et al
At high concentrations DHvit.C (and vit.C) does inhibit mitogenic stimulation of lymphocytes,
but remains noncytotoxic Ramirez I et al Free Full Text
, preserving cellular integrity.Ozaki M et al
DHvit.C is reduced to vitamin C by glutathione peroxidase Jung CH et al
, coupled with the conversion of GSH to GSSG.Ozaki M et al
Only when DHvit.C reacts with chromium (which may react with various reductants to produce...), the resulting intermediates may induce strand breaks in DNA. Stearns DM et al
(chromium is scavenged by managanese)
What about vitamin E ?
I've read that astaxanthin (found in wild salmon) can't get become a radical itself, and is able to turn vitamin C and vitamin E radicals back in its antioxidant state.
Yes, and Ive read that vitamin C reconverts radical cations of the carotenoids into carotenoids,
and that carotenoids may indeed 'repair' the various tocopherol radical cations. Mortensen A
Inversely, alpha-, beta-, and gamma-tocopherol may reduce all the carotenoid radical cations,
but astaxanthin, canthaxanthin, and beta-apo-8'-carotenal radical cations are scavenged more rapidly than the other carotenoid cations.
delta-tocopheroxyl radical can be reduced by lycopene and beta-carotene. Mortensen A et al
The order of antioxidant power seems to be:
lycopene > beta-carotene > zeaxanthin > alpha-carotene > beta-cryptoxanthin > lutein > alpha-tocopherol > capsaicin > chlorophyll a > chlorophyll b > astaxanthin > canthaxanthin.
Buratti S et al