Does the Science of Chirality Really Matter to our Skin?
In previous posts you may have noticed when I refer to certain ingredients I use an L- or D- designation, and you may have even seen this if you read ingredient labels like I do. Though these designations are commonly used, it’s not common to see what it actually means.
The L- and the D- simply note whether an ingredient is chiral or not. What does the term chiral, or chirality mean? Does it really matter if an ingredient is chirally correct? I’m going to delve into the topic briefly, and in an attempt not to bore you, I’ll break it up into three, more digestible posts.
What is Chirality?
The term chiral (prounced kahy-ruh l) is generally used to describe a molecule or material that is not superimposable on its mirror image. Our hands, for instance, are chiral where the left is not a superimposable image of the right. Just try using your left hand to shake someone’s right hand…it doesn’t quite work. Achiral describes a material or object that is identical to its mirror image. Interestingly enough, the word chiral is derived from the Greek word “kheir,” which means hand.
In nature, most molecules are chiral and it’s a fundamental property of carbon compounds. Going back to science class, all organic materials possess carbon atoms – it is essential to life. Every carbon atom has four hands, each of which must be connected to another hand (i.e. carbon to carbon (C), or other elements like hydrogen (H), oxygen (O) or nitrogen (N)).
If at least two elements attached to any single carbon atom are identical or symmetrical, these organic materials are defined as achiral. However, if none of the elements are identical, they are chiral.
How it Relates to Skin
So what does all this mean to you and your skin? Well, our skin is chiral, therefore it responds best to chirally correct ingredients.
In our cells all the amino acids (L) are left-handed, no protein in the body will contain a right-handed amino acid. Sugars (D), however, are right-handed. Ingredients that exfoliate the skin, like acids and amino acids – namely malic, lactic, ascorbic – use the L-isomers. On the flip side, ingredients that strengthen, protect and hydrate the skin, like tocopherol, beta glucosamine, fructan, use the D-isomers.
For ingredients to produce results they must be isolated to work with the appropriate isomers in our skin, rather than inundate it with both forms, which can lead to unwanted side effects or few results. Interesting, right?
In the next post I’ll cover where chirality is found (in skin care) and where it comes from.