05.28.08
Hyperpigmentation and Natural Ingredients
Skin color is influenced by melanin, and variation in skin pigmentation is attributed to the levels of melanin produced and the number of melanocytes present. Fair and darker skinned people may have the same number of melanocytes, but darker tones obtain where melanin production is higher. In addition, the rate of degradation of melanin in the epidermal layers of darker skin is lower.
Melanogenesis (melanin biosynthesis) is influenced by genetics, environmental factors, diet and medication. Many people want to use a skin lightening product to address irregular pigmentation issues including malasma, age spots (Lentigus senilis) or liver spots (associated with sun damage or aging sometimes appearing as raised spots Seborrheic keratoses) and freckles (Lentigo aestiva). Unfortunately many products on the market are either dangerous, as in the case of hydroquinone (see “about hydroquinone” below), or they don’t seem to have much effect. The good news is that you can get excellent results with a product containing safe ingredients. The bad news is that you won’t see changes overnight, so patience is required. Remember to use an effective sunblock every day whether you are on a skin brightening program or not; it is your first line of defense against further skin damage.
Many studies indicate that natural agents can help to lighten skin gradually, over time. Let’s take a look at how and why they work.
Melanogenesis
The production of melanin by specialized cells called melanocytes occurs through the action of the enzyme tyrosinase. The rate-limiting step in melanogenesis is the conversion of L-tyrosinase to melanin, through the action of tyrosinase. Controlling melanin synthesis is usually accomplished at the first step of the melanogensis process by inhibiting tyrosinase, though other products/ingredients may affect other stages of the process: physical sunscreens block UVA rays which initiate tyrosinase activity, anti-oxidants chelate metal ions like copper which catalyze tyrosinase activity, and anti-inflammatories control inflammation which can often induce hyperpigmentation because it affects proliferation and functioning of melanocytes.
We can look at melanogenesis as a three-step process, as diagrammed below:
TYROSINE
I
I ———UV light
I
I ——-tyrosinase
v
L-DOPA
I
I —Cu+
I —tyrosinase
I
v
DOPA QUINONE
I I
I I
v v
Eumelanin Pheomelanin (reddish-brown)
(brown-black)
There are many natural ingredients that work well to control melanogenesis at the first stage by inhibiting tyrosinase. These ingredients are better tolerated than hydroquinone, which has been banned for use in Europe and Japan.
STEP ONE: Arbutin from the leaves of the common bearberry (Arctophylos uva ursi), glabridin from licorice (Glycrrhiza glabra roots), catechins from green tea, paper mulberry (Brouzzometria kazinoki + B. papyrifera), Sophora flavescens (ku shen), lactic acid and ascorbic acid all work at the first stage by inhibiting tyrosinase activity.
STEP TWO: Kojic acid (a bacterial carbohydrate metabolite) works by chelating copper ions from the active site of the enzyme. Other chelators include other antioxidants and rice.
