Licorice extract, an active ingredient for hyperpigmented skin.

Pigment spots often impact the uniformity of the complexion. Some may appreciate them and even want to highlight them, while others sometimes want to camouflage them and seek solutions to diminish them.

Hyperpigmentation is defined as a disruption in the pigmentation process (melanogenesis).I t involves melanin, the pigment responsible for the natural coloration of the skin, being overproduced in certain areas, leading to the appearance of brown, red, or pink spots. These spots vary in size and affect all skin tones. They can be classified into three categories:

• the melasma or pregnancy mask, related to hormonal imbalances;

• thelentigo or sun spots, caused by excessive and repeated sun exposure;

• thepost-inflammatory hyperpigmentation which results from an overproduction of melanin following inflammation (injuries, burns, blemishes, acne outbreaks).

The use of certain perfumes and the intake of certain medications, such as contraceptive pills, can also be causes of hyperpigmentation. Furthermore,there are also instances where the amount of melanin produced by the body is not sufficient. In this case, it is ahypopigmentationwhich leads to the appearance ofwhite spots.

Melanogenesis represents the complex biological process intended to color the skin, hair, and eyes. This function is carried out by melanocytes, which synthesize pigments, known as melanins, and distribute them in the epidermal keratinocytes.

There are two chemically distinct types of melanins in epidermal cells:

• the eumelanins, brown to black pigments;

• Pheomelanins, red to yellow pigments, with a high concentration of sulfur.

The glabridin contained at over 95% in licorice extract works at several levels to regulate the phenomenon of hyperpigmentation:

• It limits the activity of tyrosinase.

  As a reminder, tyrosinase is the primary enzyme that stimulates the formation of melanin. It plays a role at various stages of the melanogenesis process, such as during the very first step which involves the conversion of tyrosine into dopamine. It has been proven that at equal concentrations, licorice extract is more effective than kojic acid at inhibiting the action of tyrosinase.

• It significantly reduces the amount of endothelin-1
  released by keratinocytes after UV exposure.

  Endothelin-1 is a mediator involved in the pigmentation process. It is produced by keratinocytes following UV exposure. It stimulates the proliferation and migration of melanocytes.

• It inhibits the activity of phospholipase A2 (PLA2).

  PLA2 is an enzyme released by epidermal keratinocytes following UV exposure or during inflammation. It stimulates tyrosinase activity and thus melanogenesis.

Note : At Typology, we use "Glycyrrhiza glabra root extract". Rich in over 95% glabridin, it reduces the production of melanin, hence its anti-spot properties and its presence in our anti-mark serum. However, from licorice, it is also possible to extract glycyrrhetinic acid (INCI name: Glycyrrhetinic Acid). This compound has contradictory properties compared to the "Glycyrrhiza glabra root extract". Indeed, it is classified as pro-melanin, meaning it stimulates melanogenesis, the process responsible for tanning. It is therefore often found in self-tanning products.

• MORTON J. F. Major Medicinal Plants: Botany, Culture, and Uses (1977).

• DELEVPOYE C. & al., Biogenesis of Melanosomes - The Chessboard of Pigmentation. Medicine/Sciences (2011).

• SARKAR R. & al. Cosmeceuticals for Hyperpigmentation: What is Available?Journal of Cutaneous and Aesthetic Surgery(2013).