on singlet oxygen in animal cells

[MrMistery]

Singlet oxygen is a reactive oxygen species which can, like other oxygen species of this kind, cause all sorts of damage to cells, known collectively as oxidative stress.
The question I want to ask regards the neutralization of singlet oxygen. A plant cell can easily neutralize this species using caroteinoid pigments. However, animal cells do not have this defensive mechanism. Antioxidants obtained from food such as polyphenols and alpha-tocoferol are effective, but what I am looking for is a cellular mechanism, mechanism I am unable to find in any book nor by looking on the internet.
Thank you.

[mith]

Is this the same as oxygen radical?

[MrMistery]

The reactivity of singlet oxygen is given by the extra energy which causes the spin of an electron to shift, changing the molecule from its natural triplet state to an energy-rich singlet state. The term "oxygen radical" is a much broader one, and includes superoxide and the more dangerous hydroxyl radical, the neutralization of both being well documented and easy to find, unlike this pesky singlet oxygen.

My best hypothesis so far is that singlet oxygen is neutralized by glutathione. Haven't been able to find that written anywhere though

[canalon]

Have you searched Medline. I found this review that might be helpful. And, if I remember correctly, there is no direct way to protect from singlet oxygen, they are either taken by antioxydants, or react to make other reactive oxygen species that can be dealt with by the cell.

[MrMistery]

yeah, after some research I was leaning towards saying that singlet oxygen is similar in that manner with the hydroxyl radical, in that it is too unstable to be neutralized with an enzymatic reaction. I know for a fact that tocopherols and polyphenols are effective, but i doubt this is the only way they are neutralized. That is why i hypothesize that glutathione, the body's own antioxidant, has a say in this.