Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Cosmetic – antiperspirant – dentifrice
Reexamination Certificate
2001-06-06
2003-03-04
Padmanabhan, Sreeni (Department: 1617)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Cosmetic, antiperspirant, dentifrice
C564S135000, C564S203000
Reexamination Certificate
active
06528074
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a novel composition having a liquid crystal structure, and in particular, to a mixture of compounds belonging to the ceramide family, sterol family and a medium suitable for cosmetics or medicaments.
DESCRIPTION OF THE RELATED ART
In order to keep smooth skin by adding moisture to the skin and inhibiting abnormal transpiration of moisture from the skin, it is considered that moisture-keeping ability of the stratum corneum of the skin has an important role. Moisture in the stratum corneum contains many water-soluble components such as free amino acids, organic acids, urea and inorganic ions, and they are considered to be concerned in the moisture-keeping of the stratum corneum, so that these substances are practically used for the purpose of improving or preventing dry or rough skin by adding them alone or in combination to cosmetics and external drug preparations for skin use.
Recently, it has been revealed that intercellular lipids in the stratum corneum control transpiration of moisture from the body and keep softness and smoothness of the skin by preventing invasion of stimulants from the outside.
The intercellular lipids are composed of a ceramide as the main component and other components such as cholesterol sulfate, palmitic acid and cholesterol. Regarding a ceramide which corresponds to a racemic compound of general formula (II) that will be described later, preparation of a ceramide composition mixed with the same components described above is disclosed in JP-A-4-327563 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”).
It has been confirmed that such an intercellular lipid in stratum corneum or ceramide composition has high moisture-keeping ability. Taking these circumstances into consideration, ceramides such as racemic ceramide, pseudo-ceramide and glycosyl ceramide have recently been obtained by certain means such as chemical synthesis or extraction from natural materials, and, with the aim of improving conditions of the skin, studies have been positively conducted on the application of foundation cosmetics and medicaments mixed with a lipid composition containing these components to the improvement of dry or rough skin.
Since ceramide is hardly soluble in water or organic solvents, for the purpose of applying ceramide to the skin, it is necessary to use it by firstly preparing a lipid composition having a specified mixing ratio so as to form a lamellar liquid crystal structure, and then effect formation of a lamellar liquid crystal phase and then converting the composition into the form of a cosmetic or medicament by adding pharmacologically acceptable base materials and fillers which do not destroy the liquid crystal phase.
It is considered that intercellular lipid in the stratum corneum is composed of a ceramide as the main component and other components such as cholesterol sulfate, palmitic acid and cholesterol, and their mixture generally forms a lamellar liquid crystal structure.
However, according to the report by Wertz, P. W. et al., uniform lamellar liquid crystal structure cannot be formed from ceramide alone or a mixture of ceramide and cholesterol (Wertz, P. W. et al.,
J. Invest. Dermatol,
vol. 87, p. 582 (1986)).
There is a report to recommend a hair protecting composition containing either ceramide or glycosyl ceramide and at least one kind of cholesterol ester (Japanese Patent 2,510,235).
According to another study, it has been reported that a lipid component was selected from the group consisting of a ceramide, a pseudoceramide, a polyester consisting of a polyol and a fatty acid, a phospholipid, a galactosyldiacylglycerol, a sphingoglycolipid, a derivative of succinic acid and a mixture thereof was used to cure xeroderma (JP-A-8-157283).
Also, there is a report stating that a mixture comprised of a composition having a liquid crystal structure, an amphoteric and/or semi-polar surface active agent, a higher fatty acid and water was prepared and made into a composition which shows excellent cosmetic durability and can improve water resistance and sebum resistance (JP-A-8-217633).
In addition to the above, with the aim of obtaining cosmetics, quasi-drugs or medicaments for use in preventing dry and rough skin, keeping skin moisture to make smooth skin and preventing aged skin, various attempts have been made to apply liquid crystal composed of ceramides and other components such as fatty acids, cholesterol, cholesterol esters, polyhydric alcohols or various lipids.
Their examples include a cosmetic for smooth skin use prepared from a liquid crystal emulsion obtained by heating and mixing at least one compound selected from ceramide, glycosyl ceramide and galactosyl ceramide with cholesterol, a fatty acid, a water-soluble polyhydric alcohol and an aqueous medium (JP-A-7-303473), a liquid crystal skin cosmetic or emulsified skin cosmetic having an effect to prevent or improve dry and rough skin, in which one or more compounds selected from ceramide and a substance having a structure analogous to ceramide, one or more compounds selected from alkylpolyglucosides and one or more compounds selected from alcohols and polyols are formulated (JP-A-9-157149), a cosmetic composition which contains a ceramide-like compound and can delay aging of skin (JP-A-10-226674) and a skin cosmetic having a liquid crystal structure in which a cholesterol ester of an iso or anteiso fatty acid, &agr;-hydroxy acid and sphingolipids such as sphingoglycolipid and sphingophospholipid are formulated (JP-A-11-60461).
In a general way, it is considered that the ceramide or glycosyl ceramide used in each of the above reports is preferably a natural type ceramide rather than a non-natural synthetic ceramide. The natural type ceramide mainly used to date has been obtained from materials such as swine skin, bovine brain, plants and cultured fungi, but they are not satisfactory for users from the viewpoint of purity, cost or unstable supply due to epidemic diseases (e.g., bovine spongiform encephalopathy) of animals to be used.
Under such circumstances, studies on the synthesis of natural type optically active ceramides have been carried out and their supply at an industrial level became possible (JP-A-9-235329).
Among these studies, a lipid composition having a lamellar liquid crystal structure, prepared by formulating a ceramide obtained by chemical synthesis and/or an optical isomer thereof, has been proposed (JP-A-11-12118).
According to this invention, however, the lipid composition is a mixture of four compounds (ceramide, acetylsphinganine, a fatty acid or cholesterol ester and cholesterol), so that it has been required not only to make a lipid composition more simple formulation, but also to show further improved function or performance.
Thus, the invention contemplates providing a lipid composition which can improve dry or rough skin and accompanying diseases by increasing moisture-keeping ability of the stratum corneum to a level higher than the conventional compositions through simple formulation and also providing a cosmetic or medicament containing this lipid composition. This cosmetic or medicament has higher ability to protect the skin from drying by adding appropriate moisture, in comparison with its counterparts in which the conventional lipid compositions are formulated.
SUMMARY OF THE INVENTION
With the aim of achieving these objects, the present inventors have conducted intensive studies and found as a result of the efforts that a lipid composition shown below, namely a lipid composition comprised of two types of synthetic ceramide and cholesterol, forms a lamellar liquid crystal structure by a blending ratio described in the following. The invention has been accomplished based on this finding.
The lipid composition of the invention is comprised of a racemic 2-acylaminoalkane-1,3-diol or an optically active compound thereof, a racemic 2-acylaminoalkane-1,3-diol having an acyl group in which at least one of the &agr;-position and &bgr;-position is substituted with hydroxyl gro
Hagiwara Toshimitsu
Ishida Kenya
Kawada Izumi
Sawano Kiyohito
Padmanabhan Sreeni
Takasago International Corporation
Willis Michael A.
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