Drug – bio-affecting and body treating compositions – Live hair or scalp treating compositions
Reexamination Certificate
1998-11-17
2002-04-30
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Live hair or scalp treating compositions
C424S070110, C424S070220, C424S070280
Reexamination Certificate
active
06379659
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an agent to enhance strength of keratin fiber which is hereinafter be referred to as a keratin fiber strengthening agent containing at least one optically active (2S,3R)-2-acyaminoalkane-1,3-diol and a method for improving strength of keratin fiber by applying the keratin fiber strengthening agent to keratin fiber by adhesion, coating or impregnation.
BACKGROUND OF THE INVENTION
Keratin is a body component such as hair, horn, nail, scale or feather which covers the outermost part of a body and is originally derived from the epidermis. Morphologically, it can be classified into a fibrous type and amorphous type. The former type is called keratin fiber and it includes hair, eyebrows and eyelashes and animal hair such as wool and dog hair.
The primary function of keratin is to protect the body of a higher animal, particularly an animal higher than a batrachian, from the outside attack. Another function of keratin is to keep the appearance of an individual body beautiful and this function has a close relation with retention and improvement of the strength of keratin. Accordingly, it is important to maintain and reinforce the strength of keratin or improve the strength of damaged keratin.
Keratin exists in the outermost part of the body so that it tends to be exposed to severe attack from the outer world. Particularly keratin fiber is susceptible to the outer influence.
For example, the physical factors in the natural world such as friction, rain, dirt, dust or ultraviolet rays and microbiological factors such as dandruff bacteria damage keratin fiber of hair. In addition, thermal or chemical irritation due to permanent waving and degreasing due to hair washing with a solvent or detergent have recently increased the frequency of hair being damaged.
Thermal and chemical irritation of permanent waving or degreasing caused by washing with a solvent or detergent decreases the tensional strength of keratin fiber owing to the damage of protein filament. For example, hair tends to reduce tensional strength according to the frequency of permanent waving. It has been reported that the strength of hair is reduced to about half of the untreated hair at the tenth treatment.
In addition, the hair so damaged and having a reduced strength loses its gloss. Such a reduction in the strength produces broken hair or spilt hair, thereby deteriorating the appearance, which causes a cosmetic problem.
It is therefore cosmetically significant to maintain and increase the strength of keratin fiber and improve the strength of damaged keratin fiber.
Keratin is mainly composed of keratin protein (keratin in a narrow sense) which is an insoluble, stable protein containing much cystine and having many disulfide bonds.
Keratin fiber has a definite structure in which protein filament of alfa keratin forms helix coils in the presence of an adhesive. This adhesive has an important role. In addition to keratin protein, keratin fiber contains a number of components. Among them, a water soluble component such as amino acid is presumed to provide keratin fiber with wetness, serving as a humidity retaining component. As an oil component, a ceramide is contained much in keratin fiber.
The ceramide is also a main component of stratum corneum lipid which binds stratum corneum of human skin and is known to play an important role as a skin barrier.
The ceramide extracted from a naturally-occurring substance has an optically active (2S,3R)-2-acylaminoalkane-1,3-diol structure. A 2-acylaminoalkane-1,3-diol has four stereoisomers (diastereomers). Among them, only the stereoisomer having a (2S,3R) configuration exists in nature. It has so far been difficult to prepare the same 2-acylaminoalkane-1,3-diol having a (2S,3R)-configuration as the naturally-occurring one except for preparing it by extraction of a ceramide from a naturally-occurring substance.
Since a ceramide extracted from an animal or plant in nature is a mixture of many ceramide components and it is markedly expensive, studies on the effect of an optically active (2S,3R)-2-acylaminoalkane-1,3-diol, which is a pure substance and at the same time has the single steric structure as that of the naturally-occurring substance, on the keratin fiber have not been reported yet.
As a substitute for the naturally-occurring substance, synthesized is a diastereomer mixture of racemic 2-acylaminoalkane-1,3-diols, that is, a mixture wherein (2S,3R):(2R,3S) is 1:1 and (2S,3S):(2R,3R) is 1:1 (with the proviso that (2S,3R)+(2R,3S):(2S,3S)+(2R,3R) tend to be unequal) (said mixture will hereinafter be referred to as “racemic ceramide”). It is commercially available under the trade name of “CERAMIDE II” (Quest Inc.) and the use of a composition obtained by mixing it with at least one cosmetically acceptable raw material has been proposed with a view to improving the rough skin or protecting the hair.
It is known (JP-A-4-327563) (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) that a composition available by using a “racemic ceramide” is effective for preventing hair from losing moisture. It is also known that a composition containing a “racemic ceramide” imparts satisfactory shape retaining properties to hair (JP-A-7-30046). Further, JPA-8-245337 proposes a method for treating keratin fiber of the skin or hair, etc., which comprises applying a composition containing a “racemic ceramide” to the skin or hair and, optionally, rinsing with water. These reports however do not include a description concerning an increase in the strength of keratin fiber. Even by the studies of the present inventors, no effect for improving keratin fiber was found from the “racemic ceramide” as described later in Examples.
The strength of protein fiber can be determined by measuring a load required for cutting keratin fiber in tension (breaking strength). Permanent-waved hair tends to have a reduced breaking strength. It has been reported that compared with untreated hair, the strength of hair is reduced to about half when permed 10 times. Many compounds have been developed for restoration of such damaged hair. Reported substances effective in restoring damaged hair include cationic hydrolysis products of protein and isoprene glycol (see
Hifu to biyo
, 29(3), 5027(1997)). These reports however do not include a description about an improvement in the strength of keratin fiber.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel keratin fiber strengthening agent which can improve physical properties of keratin fiber, such as breaking strength.
The present inventors have proceeded with an extensive study. As a result, it has been found that a composition comprising a compound represented by the formula (I) and a cosmetically acceptable raw material (base) such as oil components, lipids, sterols, lower alcohols, polyols, surfactants and other components brings about a marked improvement in the breaking strength of hair damaged by a permanent wave, treatment with an organic solvent, etc.
That is, it has been found that the composition of the present invention increases breaking strength of keratin fiber and, when applied to hair, produces effects in preventing hair splits or breaks and is curative of hair damage so that it is useful as a product of a keratin fiber strengthening agent. The present invention has been completed based on this finding and successive studies.
The present invention provides:
1) A keratin fiber reinforcing agent comprising 0.001 to 20% by weight of at least one (2S,3R)-2-acylaminoalkane-1,3-diol represented by the following formula (I):
wherein R
1
represents a straight-chain alkyl group having 9 to 17 carbon atoms and R
2
represents an acyl group having 2 to 24 carbon atoms which may contain at least one hydroxyl group or unsaturated bond.
2) The keratin fiber strengthening agent according to 1) above, wherein in the formula (I), R
1
represents a straight-chain alkyl group having 9 to 17 carbon atoms and R
2
represents a saturated acyl group having 2 t
Ishida Kenya
Ogura Miharu
Sakurai Kazutoshi
Shiroyama Kenichiro
Yamasaki Tetsuro
Howard S.
Takasago International Corporation
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