V.C. Reduces Radical Bully
by Ginger Houston-Ludlam
Redox chemistry is such an important and fundamental part of understanding how biochemistry works (and is the entire basis for “oxidative stress” at a deeper level) that I think it is worth delving into. Redox, or Reduction/Oxidation reactions, are very important, paired reactions. What I mean by that is that for this to happen, two chemicals are involved. One is oxidized and the other is simultaneously reduced.
Redox reactions happen by taking an electron (or more than one) from the chemical being oxidized and moving it over to the other chemical, thereby reducing it. Why would it be “reduced” by adding something, you ask? It is just job security for biochemists. It is totally counter-intuitive, as is the fact that the “reduced” chemical is now in the higher energy state. Remember that electrons have a negative charge. If you think like a crazed mad scientist, and understand that the total charge of the molecule has become more negative by adding the electron (and adding “electricity” to that molecule), it helps. Things which are oxidized are degraded. It has nothing to do with oxygen, except that often the recipient of the electron (and the proton that goes with it from a hydrogen molecule) is an oxygen molecule, and if this happens twice you get water. Water is a reduced form of oxygen. Get the idea?
So, here come the antioxidants, the good guys. Some pro-oxidant free-radical, like a hydroxyl radical, in a Grateful Dead T-shirt walks up to an unsuspecting molecule (let’s say a fatty acid) kicks sand in his face, pulls out a phaser, and shouts, “Your electron or your life!” Hearing the cry for help, an antioxidant (let’s say a molecule of vitamin C) rushes over (I’ll save you, Nell!) throws it’s little body in front of the fatty acid and hands the free-radical the electron out of its own pocket. (Free radical has been reduced; vitamin C has been oxidized.) The free radical, temporarily chilled out, goes on its merry way. The fatty acid has been spared being oxidized (that lipid peroxidation, so bad in Down Syndrome) and the vitamin C has become oxidized.
The vitamin C radical is not very reactive (it doesn’t go around stealing hydrogens from other molecules) and is easily converted back to it’s original form. By the way, this conversion of Vitamin C is done by an enzyme that requires the reduced form of glutathione,