Vitamin C Halts the Oxidation of Melanin giving the appearance of a brighter, more even skin tone.
I’ve had a love-hate relationship with skin brightening/ whitening actives over the years, I love to help people feel better about themselves and look younger and fresher but hate the idea of people feeling that the only way they can look beautiful is to have whiter skin. But putting that aside for a moment it is worth looking into the chemistry of how these actives work and one of my favourite actives that fits the ‘skin lightening’ claim is Vitamin C.
So Melanin is the pigment that gives skin its colour and vitamin C is an anti-oxidant.
The cosmetic chemist has, at their disposal various incarnations of vitamin C, some oil soluble, most water soluble, some highly stable, some very prone to oxidation, some long-acting some instantly reactive. But the important thing is that all these types of Vitamin C have the ability to act upon that which attacks the melanin to halt oxidation and prevent it turning a deeper shade of brown.
Melanin is an interesting group of chemicals that derive their name from the Greek word for Black/ Dark (Melas). It is the major pigment present in the skin of vertibrates and the one responsible for giving us a tan. But that’s not all it does, the melanin pathway is also involved in producing an antibiotic action on the skin and in plants and insects melanin helps to give strength to cell walls and cuticles. In addition Melanin is a powerful chelator of cations (positive ions) and as such acts as a sink for free radicals.
Chemically speaking Melanin is a Indolic Polymer – this structure is typical for eumelanin:
Indole is an aromatic (smelly) chemical that looks like this:
You can see this unit repeated through the above melanin polymer.
Indole is pretty common in nature and can be produced by a variety bacteria. It is found in human poo and (yuckily) smells exactly like that – eugh – when concentrated. Apparently in small doses it smells floral (her poo smelled like roses? No, more like Jasmine actually).
So there’s more than one polymer of melanin in a human.
We have Eumelanin – the brown and black stuff. This is also the pigment that gives rise to grey hair when it is present in small quantities and when other pigments are absent.
There is also Pheomelanin – These are pink/ red and are heavily concentrated in the lips, nipples and private parts as well as being smattered through the skin, especially in redheads who tend to have more pinky tones in their skin whereas those with brown, black or blond hair can tend to have more yellow undertones.
Then there are Trichochromes which are similar to the above but smaller in structure.
And then the Neuromelanin, a dark, insoluble polymer that resides in the brains of humans.
When we are talking about skin brightening we are primarily concerning ourselves with the Eumelanin structure as this is the pigment with the potential for the most dramatic darkening.
Melanins absorb a broad spectrum of light energy including that from the UV range (sun burning rays). Much of this chemical reaction happens at the carbonyl group (the double bond between the carbon and the oxygen) and eumelanins have these a-plenty making them the most receptive to this UV oxidation. The consequence of this reaction is an oxidation of the melanin, scientists call this the IPD reaction (Intermediate Pigment Darkening) but cosmetic chemists and the public know this as the tan.
And that brings me neatly to why I love Vitamin C as a skin brightening active.
The oxidation of melanin occurs naturally with UV exposure at the surface of the skin (ish) and as such is 100% cosmetic in nature. When there is no UV, there is no oxidation and the melanin remains light – we see this in the winter or on the skin that we keep covered up – no sun, no tan. Vitamin C has the ability to intercept the energy from the UV light (sun) before it reaches the melanin thus preventing the darkening and maintaining a lighter complexion. It does this in a ‘hands-off’ way compared to other more dramatic methods of skin lightening which typically attempt to intercept the melanin production by either attacking or down-regulating the production of tyrosine or other precursors before they become melanin. While this latter method is arguably more likely to produce a dramatic result, it is also mildly more invasive bordering on therapeutic as the body chemistry is being altered by the action of the topical product.
The down side of vitamin C skin brightening is that it is unlikely you will end up with skin lighter than your natural base colour. What this method will do is keep a lid on further darkening and correct over-pigmented areas such as scarring. On top of that there is the added benefit of vitamin C being an all-round anti-oxidant so to speak. It doesn’t just target melanin, it will protect the skin from oxidative damage of all types including pollution.
So if I’m asked to develop a gentle daily brightening cream or a cream to address patchy pigmentation from scarring (acne scars for example) then I’d look to vitamin C to do the hard yards while adding a few other ingredients to perform supporting roles.
If people want more dramatic whitening I’d typically explain the implications of that (which include making the skin more vulnerable to UV damage) before showing them through the vast array of tyrosine type inhibitors which include but are not limited to Bearberry extract.
Don’t you just love chemistry!
PS: I always refer to scientific reference papers and books to check my chemistry but I don’t always publish these links. I am always more than happy to discuss providing a fully referenced article based on what I write on the blog to clients but this will come with a cost. Typically in these situations I will also add a section focusing on the desired outcome of the client, looking at how they might achieve the product they have in mind or explaining how the product they currently have works. Prices for this start at $300 plus GST and you can contact me on email@example.com