What are
The lightening creams belong to the large group of cosmetics designed to counteract the imperfections of the time.
Data in hand, in Italy over 40% of women between the ages of 50 and 60 declare hypermelanic spots on their skin. Hence the need to use lightening creams to counteract the flowering of these dark spots, the result of an inhomogeneous distribution of melanin in the skin.
deepening
Melanin is produced with a complex series of chemical reactions that start with the oxidative catalysis of tyrosine by the tyrosinase enzyme.
This synthesis takes place within the melanosomes, cellular organelles contained in the melanocytes. After that, the melanosomes move along the dendrites of the melanocytes and are transferred to the keratinocytes. Only at this point, the skin will tan, or will it give rise to skin spots.
Lightening substances
The lightening substances currently used to combat skin spots are different.
Among the most effective ingredients present in modern lightening cosmetic formulations we recall:
- Ascorbic acid (or vitamin C);
- Azelaic acid, is a natural substance produced by the yeast Pityrosporum ovalis ;
- Kojic acid (or cogic), another natural molecule produced from fungi belonging to the genus Aspergillus ;
- Arbutin, a substance naturally present in bearberry;
- Ellagic acid, a molecule with a strong antioxidant action present in numerous plants;
- Niacinamide (also known as nicotinamide, vitamin PP or vitamin B3), is a molecule produced by the body that - if applied topically - is able to exert a lightening action.
- Nonapeptide-1, a particular type of biomimetic peptide;
- Glycyrrhizin, contained within licorice root extract.
Action mechanism
The aforementioned lightening substances are able to carry out their activity mainly through different mechanisms of action:
- By inhibiting or deactivating the enzyme tyrosinase, in order to block melanin biosynthesis processes from the beginning;
- Preventing the migration of melanosomes to keratinocytes. In this case, therefore, the melanin has formed but does not reach the surface layer of the skin.
- By counteracting the action of the melanotropic hormone MSH (Melanocyte Stimulating Hormone) produced by the pituitary gland. The task of this hormone is precisely to stimulate the synthesis of melanin by acting directly on the melanocytes present in the skin.
The table below lists the main lightening substances and their corresponding mechanism of action.
Cosmetic ingredient | Action mechanism |
Kojico acid | Deactivation of tyrosinase due to chelation of the copper ion present in the enzyme. |
Ascorbic acid | The antioxidant activity counteracts the oxidative phenomena at the base of melanogenesis and accelerates skin turnover. |
Azelaic acid | Inhibitory properties against tyrosinase. |
glycyrrhizin | Competitive inhibition of the tyrosinase enzyme. |
Ellagic acid | Inhibits tyrosinase by copper chelation + antioxidant effect. |
Arbutin | Inhibits the enzyme tyrosinase. |
Niacinamide | It prevents the transfer of melanosomes from melanocytes to keratinocytes. |
Nonapeptide-1 | It is an antagonist of the MSH hormone and, moreover, it also has an inhibitory action against tyrosinase. |
Effectiveness
The effectiveness of all the lightening substances described so far is now proven. However, their effect on the concentrations of use allowed in cosmetics is rather bland; it follows the need to use lightening products consistently and for prolonged periods.
Alternative methods
Much more effective in depigmenting terms, but also dangerous if used improperly, are chemical exfoliants, often used in combination with the aforementioned ingredients. These substances, among which the mandelic acid and the glycolic acid stand out for their reputation, have essentially the purpose of removing dead cells, rich in melanin, which tend to "cement" on the surface. By acting in this way, the exfoliants release the underlying, clearer and brighter epidermal layers, and promote epidermal turnover by stimulating the formation of new cells. These products, although potentially very effective, must be absolutely avoided in the event of exposure to the sun, during which creams can be used with cosmetic lightening ingredients, as long as they are free of exfoliants and photosensitizing agents, and combined with a high protection against sun. the synthesis of new melanin with browning of the areas predisposed to the onset of hypermelanosis.
