After taking an Anthropology class
entitled “Many Diseases, Few Causes” last summer, I have a whole new
appreciation for antioxidants. We talk a lot about those in terms of olive oil
because of the many polyphenols that are thought to be in olive oil that have
antioxidant properties (assuming it’s extra virgin and not adulterated with
oils that don’t have those health benefits). But I guess a question that people
rarely ask is “why do we need antioxidants”? It’s interesting, we hear about
free radicals and how they cause aging and wrinkles, and how antioxidants can
make us look younger. We hear about how dark chocolate and resveratrol in wine
are good for us, but we don’t know why. How does olive oil have such magic
properties?
The answer is pretty simple,
actually, the antioxidants in it help combat reactive oxygen species in our
body. There is a paradox that exists in biology: oxygen is such an important
molecule (considering that it is necessary for us to undergo cellular
respiration and, you know, live and stuff) but it can also form very dangerous
radicals, such as the superoxide radical (pictured below). These radicals can
damage the body and cause aging, cancer, and so many other diseases. This is
termed oxidative stress, and is caused by the radical causing the oxidation of
other bodily molecules, and in doing so damaging key pathways and leading to
many downstream effects that are harmful to the survival of the individual.
That
lone electron on the left oxygen wants to have a friend, so it abstracts a
hydrogen from a neighboring molecule. But then the neighboring molecule doesn’t
have that electron anymore, so it goes off looking for one. This process
repeats and disaster strikes. Of course, this is where antioxidants come in.
Look at them and let me know what you think of their structures:
Resveratrol, commonly found in red wine.
Hydroxytyrosol, commonly found in
olive oil.
These are two naturally occurring antioxidants. What they
have in common is that they contain hydroxyl groups with easily abstractable
hydrogens, and aromatic rings. Resveratrol even has a double bond that is
conjugated with the rings. The reason this is so important is resonance. If one
of those hydrogens gets abstracted, then by resonance the double bond will
donate one electron to form a different resonance contributor with the radical
on a different atom. The transfer of the radical around the ring forms a
network of different resonance contributors that allows for stability. Because
this radical compound is so stable, it is less likely to continue the chain
reaction of causing a different radical. It’s like a sink for radicals, and it
is this resistance to further oxidizing important pathways that garners these
compounds the name “antioxidants”. There’s a reason that polyphenols are a
class of antioxidants (Hint: polyphenols have many aromatic rings…so you can
imagine how stable those would be in the face of radicals). In the fight
against aging, cancer, and many other diseases, it would appear that reactive
oxygen species are one of our main enemies. However, with such strong things as
antioxidants (as those from olive oil) on the front lines, we may just have a
fighting chance!
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Nice explanation, Vijay. We will discuss anti-oxidants as we read the article on anthocyanins. I'll ask you to open class with your brief, but clear explanation. Bravo!
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