Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2000-10-10
2003-02-18
Dees, Jose′ G. (Department: 1619)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C514S053000, C514S847000
Reexamination Certificate
active
06521239
ABSTRACT:
The invention relates to the use of at least one auxin in a cosmetic composition, as an agent for promoting the synthesis of skin lipids.
In particular, the compositions of the invention are intended for stimulating the synthesis of the total lipids of the skin, particularly those of the epidermis.
The invention also relates to a moisturizing cosmetic composition comprising at least one auxin.
Human skin consists of two compartments, namely a deep compartment, the dermis, and a superficial compartment, the epidermis.
The dermis gives the epidermis a solid support. It is also the epidermis' nourishing factor. It consists mainly of fibroblasts and of an extracellular matrix composed mainly of collagen, elastin and a substance known as ground substance, these components being synthesized by the fibroblasts. Leukocytes, mastocytes and tissue macrophages are also found therein. It also contains blood vessels and nerve fibres.
The epidermis is in contact with the external environment. Its role consists in protecting the body against dehydration and external attack, whether this is chemical, mechanical, physical or infectious attack.
Natural human epidermis is composed mainly of three types of cells, namely keratinocytes, which form the great majority, melanocytes and Langerhans cells. Each of these cell types contributes, by virtue of its intrinsic functions, towards the essential role played in the body by the skin.
The cells constituting the epidermis are delimited by an intercellular lipid domain. During differentiation, the phospholipids, whose role is to develop the fluid structure of the cell membranes in the live layers of the epidermis, are gradually replaced with a mixture composed mainly of fatty acids, cholesterol and sphingolipids.
These lipids are organized in specific lamellar structures whose integrity depends not only on the quality of the fractions present but also on their respective proportion. This lamellar structure of the lipids in the intercellular lipid domain of the epidermis is responsible for the skin's fluidity and thus its suppleness.
The lipids are also responsible for the “barrier” properties of the epidermis, particularly of the stratum corneum.
Epidermal lipids are synthesized mainly in the live epidermis. They consist mainly of phospholipids, sphingolipids, cholesterol, free fatty acids, triglycerides and cholesterol alkyl esters.
Phospholipids are essential for making cell membranes. They play an important role in mediating extracellular signals and in forming free aliphatic chains used for the production of energy. They constitute a reservoir of free fatty acids required for making sphingolipids.
Sphingolipids (or ceramides) are essential for maintaining the multilamellar structure of the interco-neocytic lipids. They are also essential for water exchanges and for the “barrier” function of the epidermis.
Cholesterol plays a primordial role in moisturizing the skin and in the “barrier” function of the epidermis.
Free fatty acids play a major role in maintaining the lamellar structure of the lipids of the stratum corneum, but also in making cell membranes, in which they are responsible for the membrane fluidity, as well as in physiological processes such as the functioning of receptors or enzymatic activity.
The essential role played by the skin lipids and the importance of their integrity may thus be appreciated.
It is known, unfortunately, that the skin lipids, particularly the lipids of the epidermis, are influenced by genetic factors, ageing, the diet, the seasons, environmental factors, external attack and/or certain pathologies (for example scurvy or pellagra). The consequence of all these factors is to adversely affect or modify the composition of the skin lipids or to reduce their amount, which invariably leads to dry skin. It is known, for example, that the absence of the lipid component from a diet results in skin in a poor state of health. The absence of lipids leads to a general deterioration in health and particularly to the appearance of flaky skin with a concomitant increase of the increase in transepidermal water loss.
The skin lipids are thus essential for maintaining the water “barrier” of the skin.
It is also known that the lipids of the epidermis also have an influence on the activity of certain enzymes in the skin which are involved in maturation and desquamation of the stratum corneum.
Variations in the level and type of lipids present in the stratum corneum thus have an influence on the “barrier” function of the stratum corneum, the water content and the state of the skin.
It is also known that at the menopause, women complain that their skin feels tight and that it has the appearance of “dry skin”, or even of the appearance of xerosis. Without wishing to establish any theory, given that skin lipids play an important role in moisturizing the skin and that the hormonal deficits associated with the menopause are accompanied by a general slowing-down in cell metabolism, it can be assumed, at any rate, that the sensation of tight skin or dry skin which women experience is linked in particular to a decrease in the amount of total lipids in the skin.
It may thus be appreciated that it is important to be able to stimulate the synthesis of skin lipids in order to maintain and/or restore their integrity so as to allow them to carry out the important roles for which they are responsible.
In this respect, the Applicant Company has discovered, surprisingly and unexpectedly, that certain plant hormones, or phytohormones, particularly auxins, have the property of stimulating the synthesis of lipids, particularly the total lipids of the skin.
Auxins are phytohormones, i.e. plant hormones in the same way as gibberellins, cytokinins, ethylene or abscissic acid.
Plant hormones are chemical messengers which serve as intermediates in intercellular communication in higher plants. They are in general relatively small molecules which act in very small amounts. Plant hormones are involved in regulating the growth processes of plants.
Auxins are plant hormones which are involved in regulating the elongation of plant cells and in the growth of plants in response to a unidirectional stimulus, this phenomenon being known as tropism (see “Plant propagation by tissue culture”, George E. F. and Sherrington P. D., 1984, Exegetics Limited or “Dictionary of natural products”, Chapman and Hall, 1997).
In the prior art, auxins are known for their use in regulating calcium flow across cell membranes (EP 240 257), or as forming part of anti-tumour compositions (FR 2 597 339), for treating surface wounds on the skin (EP 60 553) or for treating burns or ulcers (EP 103 878).
To the Applicant's knowledge, the use of at least one auxin to stimulate the synthesis of the total lipids of the skin has never been described in the prior art.
One subject of the invention is thus the use, in a cosmetic composition, of an effective amount of at least one auxin, the auxin or the composition being intended to stimulate the synthesis of the total lipids of the skin.
The term “auxin” is used to describe natural and/or synthetic substances which stimulate the elongation of the coleoptiles and stalks of plants.
Thus, according to the invention, the auxins can be of natural or synthetic origin.
The expression “natural auxin” means any auxin, or any preparation containing it, which is present in the natural state in at least one plant.
The expression “synthetic auxin” means any compound which has activity similar or identical to that of natural auxins, but which has been obtained by chemical synthesis or by biotechnology.
Thus, in the text hereinbelow, the term “auxin” is intended to denote a purified natural or synthetic auxin or any preparation containing a natural or synthetic auxin.
The auxins which can be used according to the invention are those described in the two reference works cited hereinabove in the text. Among these, mention may be made, for example, of 3-indolacetic acid (IAA), 4-chloro-3-indoleacetic acid (4-Cl-IAA), phenylacetic acid (PAA); 3-indolebuty
Breton Lionel
Girerd Florence
Renault Beatrice
Burns Doane Swecker & Mathis L.L.P.
Dees Jose′ G.
Haghighatian M.
Societe L'Oreal S.A.
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