Use of a composition containing at least one oxidation-sensitive hydrophilic active principle and at least one N-vinylimidazole polymer or copolymer

Abstract

The invention relates to the use of a composition contains at least one oxidation-sensitive hydrophilic active principle selected from the group consisting of ascorbic acid and its derivatives and at least one non-crosslinked N-vinylimidazole polymer or copolymer, the active principle and the said polymer or copolymer both being in the aqueous phase, for lightening and / or depigmenting the skin and / or hair, including body hair.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to the use of a composition comprising at least one oxidation-sensitive hydrophilic active principle and at least one N-vinylimidazole polymer or copolymer, preferably in a physiologically acceptable medium comprising an aqueous phase. Preferably the use is a cosmetic and / or dermatological use related to lightening or depigmenting the skin and / or the hair, and is thus preferably targeted to skin and / or hair to be lightened.[0003] 2. Background of the Invention[0004] It is known to introduce, into cosmetic compositions, various active principles intended to contribute specific treatments to the skin and / or hair. However, some of these active principles exhibit the disadvantage of being unstable in an aqueous medium and of easily decomposing on contact with water, in particular because of oxidation phenomena. They thus rapidly lose their activity over time and this instability conflicts with the desired effectiveness...

AI Technical Summary

Benefits of technology

[0013] One object of the present invention is to provide a composition comprising an oxidation-sensitive active principle selected from the group consisting of ascorbic acid and its derivatives, which exhibits good cosmetic properties, both with regard to touch and with regard to tolerance, the preservation of which over time does not require specific precautions, and which retains the depigmenting and / or lightening ability of the active principle.

[0014] The Inventors have discovered that the use of non-crosslinked N-vinylimidazole polymers or copolymers in compositions in which the aqueous phase includes an oxidation-sensitive active principle, such as ascorbic acid, makes it possible to achieve the abovementioned object.

[0018] The use of such a composition furthermore exhibits the advantage of acting both by inhibiting tyrosinase, thus reducing melanogenesis, and also by inhibiting the dendricity of melanocytes. The depigmenting effect thus obtained is much greater than that obtained, for example, with ascorbic acid alone, which acts solely on melanogenesis.

[0023] In a particularly advantageous aspect, the oxidation-sensitive hydrophilic active principle is ascorbic acid. Other preferred principles meet the above requirements and possess the ability to lighten the skin and / or the hair.

Problems solved by technology

However, some of these active principles exhibit the disadvantage of being unstable in an aqueous medium and of easily decomposing on contact with water, in particular because of oxidation phenomena.

They thus rapidly lose their activity over time and this instability conflicts with the desired effectiveness.

Unfortunately, because of its chemical structure (of .alpha.-ketolactone), ascorbic acid is highly sensitive to certain environmental parameters and in particular to oxidation phenomena.

These solutions have disadvantages with regard to the cost and the complexity of the manufacturing operations and significant restrictions with regard to use.

However, these solutions exhibit the disadvantage of resulting in sticky formulations, the cosmetic quality of which is difficult to improve.

Furthermore, the presence of a high concentration of these compounds can lead to phenomena of irritation.

A major disadvantage of such solutions results from the lack of freshness on application.