Lisa’s curious about chirality: I recently learned about products that are chiral. They do sound more beneficial (since I now understand chirality), but does that necessarily mean that the other products that don’t claim to be chiral are no good?
The Left Brain’s leftist reply:
You must be taking Organic Chemistry right now if you’ve learned what chirality means. It’s an interesting concept and one that this particular Beauty Brain had a difficult time grasping. Let me explain for the benefit of the rest of our community.
What is chirality?
Chirality essentially means that an object can’t be superimposed on its own mirror image. The easiest way to think about it is to look at your hands. They’re the same size and shape, right? But you can’t put your left hand in your right glove because they’re chiral. If that still doesn’t make sense, here’s a clever online game you can play that does a better job of explaining the concept.
The idea of chirality has implications for chemical synthesis and pharmaceuticals. Some chirally uniform drugs work better than others because the body has receptors that can only interact with molecules in a specific shape. So chirality is very important for medicine.
Can cosmetics be chiral?
Unfortunately, in cosmetics, chirality doesn’t really matter. There are no receptors on the outer layer of your skin or hair that will accept molecules from your cosmetics. They simply work on the surface and penetrate the skin slightly. They don’t interact with cells in the same way that drugs do. And if there isn’t this interaction, whether the molecule is chiral or not doesn’t much matter. So for skin cleansers, wrinkle creams, hair conditioners, styling products, and the vast majority of other cosmetics, it makes no difference.
But that doesn’t stop some cosmetic companies from claiming their products are chiral. One company in particular, called Franche, even references the fact that the 2001 Nobel prize in chemistry was awarded for the creation of a catalytic process to manufacture chiral molecules. But as far as I can tell, this really has nothing to do with the ingredients used in Franche cosmetics. For example, look at Franche’s Cleansing Crème Mousse. The only ingredient where chirality is relevant is D-panthenol. And that ingredient doesn’t do ANYTHING for hair from a rinse off product. So shame on them for trying to using misleading science to influence consumers. (Note: If Franche has any data to back up their assertions, we’d be more than happy to reconsider these comments.)
The Beauty Brains bottom line
Chiral cosmetics are a crock.
{ 7 comments… read them below or add one }
Whew…I am really glad to hear I don’t have to worry about chirality in my cosmetics…whatever that exactly MEANS! Thanks for putting my mind to rest!
I’m so glad I don’t have to THINK about chirality when it comes to cosmetics. Come on, cosmetics is suppose to be FUN! Chirality just brings me back to o chem and biochem, and that’s just NOT fun!!!
Wow, I kind of suck at chirality. It took me such a long time to figure out the pairs in the game. I could have done so much better in my science/chemistry classes if I just foused and took my time instead of giving up.
My Chemical Engineer-majoring son had this to say about it:
Why a cosmetic product would be bragging about a “chiral” ingredient makes no sense. Chirality in and of itself tells you nothing about something’s properties. It would be a little more meaningful if they told you which of the two enantiomers was an ingredient, but even then, it seems irrelevant. Opposite enantiomers have exactly the same properties as one another, with only two exceptions: they rotate polarized light in opposite directions (which has nothing to do with cosmetics, or anything else, for that matter), and sometimes the body can only metabolize one enantiomer and not the other. Almost all the sugars your body can metabolize are D-sugars, whereas all the amino acids your body can metabolize are L-amino acids. D and L are the two types of enantiomers. A sugar packet could say “contains a chiral ingredient”–but since all sugars are chiral, this is redundant. What’s more, saying the sugar in the packet is chiral doesn’t even mean it’s the correct enantiomer. It could be the worthless L-sugar that would go right through you. But none of this matters, since the original post says that there are no enantiomerically specific metabolic pathways in skin absorption.
It’s nice to know those tuition checks have been well spent.
So, if you were to use a serum with vitamin C, whether it’s L-ascorbic acid or not, doesn’t matter?
Karen’s comment: “…Opposite enantiomers have exactly the same properties as one another, with only two exceptions: they rotate polarized light in opposite directions (which has nothing to do with cosmetics, or anything else, for that matter), and sometimes the body can only metabolize one enantiomer and not the other.”
Is this strictly correct? I thought the problem with thalidomide was that both enantiomers could be metabolised, but in different pathways with vastly different effects (ie. one reduced morning sickness, the other was a teratogen without reducing nausea).
I think her comment was a broad generalization. To say that those two properties are the only difference between “every” enantiomer is an overstatement. Another property is that some enatiomers will interact with the body metabolism in different ways.