Thursday, October 4, 2012

The Beauty of Science #2: Antioxidants and Free Radicals

Now that we've established a foundation, let's delve right in. Today we're going to talk about antioxidants - what they are, what they do, and why that's believed to be important in areas like anti-aging and preventative health care. It starts with free radicals.
People commented that they liked the handwritten explanations. I kind of like them, too. They make everything seem less sterile, somehow.

Remember bonds? Sometimes they break in a way that leaves one electron on each atom. Electrons like to be paired (like people, perhaps), so one unpaired electron = bad business. Having an unpaired electron makes an atom or molecule highly reactive; that is, they rush out and do things like steal electrons or hydrogens from molecules that need them, making the victim molecule unstable and likely to degrade.
I just realized that I should have used a new letter. This is a new B! One with two electrons, haha. Not the one that just split from A. Eep. Sorry for the confusion!

Or, worse, the chain propagates - the victim molecule also turns to a life of crime, and steals an electron from another molecule, creating yet another free radical. And so on, and so on.

In a living body, this means that molecules in cells are robbed of their electrons by free radicals. This is believed to lead to cell death, or mutation - very bad things. (Cell mutation is thought to be a cause of cancer). This, er, free radical violence, is also currently believed to speed up the aging process.
In ingredient lists, Vitamin E shows up as "tocopherol."

Enter the heroes: antioxidants. How do they work? Basically, antioxidants go around reacting with the free radicals before they get a chance to react with some other poor, unsuspecting molecule. Think of it this way: antioxidants tie up loose ends before they get a chance to unravel.

The standard mechanism:
If you recoiled, fear not. The bottom line: the radical reacts with the antioxidant, which can afford to give up a hydrogen (in this case) to make the radical happy. The antioxidant absorbs the loss and becomes stable, so it does not continue the radical chain, and all is well.

A couple more things: Vitamin E is soluble in fats (no, not the omg-I-don't-fit-in-my-jeans fats - we're talking about lipids, which are non-water-soluble molecules) and other vitamins like C are soluble in water, so current recommendations are for both kinds, since your body is made up of both fats and water. Also, this is not the only mechanism for cleaning up radicals, but they all work similarly. The basic line is that the antioxidant can absorb the loss so that the chain doesn't perpetuate.

That wraps this session up, folks. If you're feeling overwhelmed, it may help to go back to my primer and look at it all again, now that you have a purpose at hand. Sometimes that helps. If you're still confused, feel free to drop a comment below, or send me an email. I welcome all questions - I only hope I can answer them!

Smith, Janice. Organic Chemistry, 3rd ed. McGraw-Hill, 2006.
Office of Dietary Supplements, National Institutes of Health

*Special thanks to S. for proofing my work :)