Drug – bio-affecting and body treating compositions – Plant material or plant extract of undetermined constitution... – Containing or obtained from gramineae
Reexamination Certificate
2000-10-10
2004-06-22
Venkat, Jyothsna (Department: 1615)
Drug, bio-affecting and body treating compositions
Plant material or plant extract of undetermined constitution...
Containing or obtained from gramineae
C424S401000, C514S944000
Reexamination Certificate
active
06753020
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a composition to enhance the rate of skin cell renewal or exfoliation and to a method of increasing the skin cell renewal rate without an increase in skin irritation. In particular, the present invention relates to a composition containing a skin benefit agent that includes oat extract. The present invention also relates to a method of increasing the rate of skin-cell renewal by applying a composition to the skin, wherein the composition comprises an amount of oat extract effective to increase skin cell turnover or renewal rate.
The skin of humans is continually assaulted by environmental conditions such as the sun, wind, and pollution. These environmental assaults weather or age the skin causing, among other things, wrinkles, age spots and other undesirable skin conditions. In addition, the effects of natural aging also cause the skin to wrinkle.
These negative effects can be prevented or at least ameliorated by applying skin care cosmetics that contain skin benefit agents according to the present invention.
Human skin may be classified into two major parts: the outer layer or epidermis and an underlying layer or dermis. The dermis contains among other things, blood vessels, nerves, collagen, elastin, and fibroblast cells, which are responsible for the biosynthesis of collagen and elastin.
The epidermis itself also may be considered to consist of two major zones, an inner or malpighian layer and an outer or horny layer. The malpighian layer, a living tissue, may be further divided into basal, spinous, and granular layers. The horny layer, a dead tissue, is also referred to as stratum corneum.
In the natural process, basal cells in the basal layer move outward through the spinous and granular layers to become dead cells called corneocytes, in the stratum corneum. The stratum corneum consists of approximately 14 layers of corneocytes. In the normal skin it takes about 14 days for the basal cells to move from the basal layer to the end of the granular layer and to become corneocytes, and another 14 days to reach the outermost layer of the stratum corneum, where they are naturally shed or exfoliated. This process of forming corneocytes is called keratinization, and stratum corneum is the natural products produced by this process. The stratum corneum is the skin tissue that one feels when touching the skin. Usually, it takes about 28 days for cells of the basal layer to move outward to the surface in the course of making new skin.
It is thought that by increasing the natural desquamation rate (the cell renewal or cell turnover rate) of the outermost part of the stratum corneum and thus exposing lower layers of the stratum corneum, the appearance of the skin will be improved. Many substances are known to increase the rate of natural desquamation but recently compositions containing hydroxycarboxylic (alpha and beta) acids have received an increasing amount of attention.
A drawback to the use of hydroxycarboxylic acids is that they are most effective at low pHs, about 4.0 or less. It appears, however, that there exists a strong correlation between the degree of exfoliation (cell renewal rate) and the degree of irritation. Thus, at pH of about 4.0 or less, the hydroxycarboxylic acids show significant stimulation of cell renewal but also a fair degree of skin irritation. On the other hand, as the pH approaches neutral (7.0), the cell renewal rate decreases while there is little or no irritation. Thus, it would be desirable to achieve an increase in the rate of natural desquamation without further increasing the irritation of the skin. It would be most desirable to provide for enhanced skin desquamation at a neutral pH. The present invention solves that problem by providing for enhanced skin desquamation at a neutral pH without undue irritation.
One method for ameliorating the irritating effects of the alpha-hydroxy acids is described in GB 2,328,374. There, a complex of oat protein and malic acid is provided where the malic acid is chemically bonded or complexed with hydrolyzed oat protein.
Another method is disclosed in U.S. Pat. No. 5,888,521. There, the composition contains an alpha-hydroxy acid and an oat extract that contains less than 1% &bgr;-glucan. It is noted that the oat extract synergistically enhances the rate of skin desquamation produced by the hydroxy acid.
None of this art, however, teaches or recognizes that an oat extract, by itself, is effective in enhancing mammalian skin cell renewal rate at near neutral pH, without undue skin irritation.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a cosmetic or dermopharmaceutical composition for topical use comprising an oat extract and a carrier. In accordance with this aspect of the present invention, there is provided a composition comprising an oat extract present in a therapeutically effective amount in a topically acceptable vehicle for application to human skin to enhance the rate of skin desquamation beyond the rate of naturally occurring skin desquamation. In other words, this aspect contemplates the use of an oat extract in the preparation of a cosmetic composition to enhance the rate of skin desquamation beyond the rate of naturally occurring skin desquamation.
Advantageously, compositions of the present invention need not contain known skin desquamation agents such as hydroxy acids to achieve enhanced skin desquamation rates. Therefore, in one aspect of the present invention, the compositions may be substantially free or completely free of known skin desquamation (exfoliation) agents such as hydroxy acids. The term “substantially free” is used to mean that the compositions contain less than about 0.1% known skin desquamation agents such as hydroxy acids.
The oat extract is derived from oat, avena sativa. Preferably, the oat extract is a hydroglycolic extract, is soluble, and does not contain &bgr;-glucan. In other words, the oat extract does not contain a measurable amount of &bgr;-glucan, e.g., less than about 0.01%. The oat extract may be incorporated into a solvent for ease of handling. For example, in a preferred embodiment, the oat extract is incorporated in a 1:1 v/v mixture of 1,3 butylene glycol and water.
In one embodiment, the oat extract contains from about 10% to about 90% carbohydrate and from about 10% to about 90% protein.
Generally, the composition contains from about 0.01 to about 99 percent by weight of the total composition. Preferably, the concentration of oat extract ranges from about 0.05% to about 30%, more preferably from about 0.1% to about 15%.
Preferably, the composition has a pH in the range from about 5.0 to about 9.0, preferably from about 6.0 to about 8.0.
Another aspect of the present invention includes a method of increasing the rate of skin exfoliation or desquamation comprising topically applying a cosmetic composition containing an amount of an oat extract effective to enhance the rate of skin cell desquamation beyond the naturally occurring rate of skin cell desquamation. In this aspect, the method includes topically applying to the skin a composition comprising an oat extract in an amount and for a period of time sufficient to increase the rate of natural skin desquamation.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, a composition acceptable for topical application to the skin comprises an oat extract and a carrier. Compositions of the present invention need not contain known skin desquamation agents such as hydroxy acids to achieve enhanced skin desquamation rates. Therefore, in one aspect of the present invention, the compositions may be substantially free or completely free of known skin desquamation (exfoliation) agents such as hydroxy acids.
The oat extract useful in the present invention is derived from oat, avena sativa. Preferably, the oat extract is a hydroglycolic extract, is soluble, and does not contain &bgr;-glucan. In other words, the oat extract does not contain a measurable amount of &bgr;-glucan, e.g., less than about 0.01%.
Alticor Inc.
Brinks Hofer Gilson & Lione
Nichols G. Peter
Venkat Jyothsna
LandOfFree
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