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

Abstract

The invention relates to the use of a composition containing, in a physiologically acceptable medium having an aqueous phase, 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 polymer or copolymer both being in the aqueous phase, for preventing or combatting the harmful effects of UV radiation and / or of pollution on the skin, in particular loss of firmness and / or of elasticity of the skin.

Description

[0001] 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 in a physiologically acceptable medium comprising an aqueous phase. Preferably the use is cosmetic or dermatological, and preferably relates to treating the skin and / or mucous membranes against UV, pollution, free radicals, and sunburn.[0002] 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.[0003] Attempts have thus been made for a long time to formulate ascorbic acid or vitamin C because of ...

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 activity in combatting free radicals of the said active principle, for preventing or combatting the harmful effects of UV radiation and / or of pollution on the skin, in particular the loss of firmness and / or of elasticity of the skin.

[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 or one of its derivatives, makes it possible to achieve the abovementioned object.

[0083] The composition according to the invention can also be used for the manufacture of a dermatological preparation comprising an aqueous phase which is intended to prevent or combat harmful effects of UV radiation and / or of pollution on the skin.

[0084] In another embodiment, the composition according to the invention can be used for the manufacture of a dermatological preparation comprising an aqueous phase which is intended to prevent or combat loss of firmness and / or elasticity of the skin.

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.

In point of fact, these radicals result in significant oxidative damage, in particular in cell membranes (permeability of the membranes), cell nuclei (destruction of DNA), and tissues, in particular connective tissue (decomposition of elastin and collagen fibres).

This damage results in particular in the loss of firmness and elasticity of the skin.

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