Note: Descriptions are shown in the official language in which they were submitted.
i~79016
WHITENING COSMETIC
Background of the Invention
l. Field of the Invention
The present invention relates to a whitening
cosmetic incorporated with kojic acid. In particular,
it relates to a kojic acid-containing whitening cosmetic
having not only an improved stability against coloring
but also an enhance whitening effect.
2. Description of the Prior Art
Kojic acid, i.e., 5-hydroxy-2-hydoxymethl-y-pyrone,
is a compound which can be obtained by the fermentation
of fungi of, e.g., Aspergillus genus. It is known that
the compound functions as an tyrosinase inhibitor.
Whitening cosmetics utilizing the function of the
compound are known and disclosed in Japanese Patent
Publication No. 18,569/81 and Japanese Patent
Application (Laid Open) No. 3,538/78.
Whitening cosmetics, in particular cosmetic creams,
containing kojic acid as an active ingredient are liable
to discoloration to yellowish brown when exposed to heat
or light, and the density of the cosmetics tends to be
increased with the lapse of time, thus impairing their
value as an article to be marketed.
~escription of the Invention
It is therefore an object of the present invention
; to provide a whiteninq cosmetic having an improved
stability against coloring with the lapse of time.
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It is another object of the present invention to
provide a whitening cosmetic having an enhanced
whitening effect.
It has now been found that the colori~g can be
markedly reduced and the whitening effect by kojic acid
can be intensified when cyclodextrins are incorporated
into a cosmetic in combination with kojic acid, or when
kojic acid included by cyclodextrins is incorporated
into a cosmetic.
Accordingly, there is provided by the present
invention a whitening cosmetic having not only an
improved stability against coloring but also an enhanced
whitening effect, which comprises cyclodextrins and
kojic acid, or kojic acid included by cyclodextrins.
Detailed Description of the Invention
Kojic acid is a known compound obtainable by the
fermentation of fungi ~belonging to such generics as
Aspergillus, Penicillium, Gluconobacter, and the like.
Cyclodextrins to be used in the present invention in
combination with kojic acid include a-cyclodextrin, ~-
cyclodextrin and y-cyclodextrin. Of these compounds, ~-
cyclodextrin can be most preferable.
Cyclodextrins can be used in an amount of from 0.5
to 10 parts by weight, per 1 part by weight of kojic
acid.
Xojic acid can be included by cyclodextrins in
advance to its incorporation into cosmetic base
materials.
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Inclusion of kojic acid by cyclodextrins can be
carried out in the following manner: Cyclodextrins are
dispersed into water, and then kojic acid iS gradually
added thereinto with stirring until they are completely
dissolved. The thus prepared included kojic acid, or
kojic acid included by cyclodextrins, may be freeze
dried.
In the above preparation, there can be used 0.5 to
parts by weight of cyclodextrins, per 1 part by
weight of ko~ic acid. Most preferably, 4 parts by
weight of cyclodextrins is used per 1 part by weight of
kojic acid.
In the present invention, the combination of kojic
acid and cyclodextrins or included kojic acid is
incorporated into ordinary cosmetic base materials to
prepare toilet waters or toilet lotions, cosmetic
creams, cosmetic emulsions or milky lotion, packs, etc.,
which are to be applied to the human skin. KoJic acid
may be incorporated into cosmetic base materials in an
amount of from 0. oi to 2% by weight not only in the case
where it is used together with cyclodextrins but also in
the case where it is included by cyclodextrins in
advance to its incorporation into base materials.
The cosmetics of the present invention may be
formulated into a toilet water or a cosmetic lotion. In
preparing toilet waters or cosmetic lotions according to
the present invention, moisturizers, skin nutrients,
etc. are dissolved into purified water, and
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preservatives, perfumes, etc. are dissolved into an
alcohol. The two solutions are then mixed at room
temperature to give desired products. Kojic acid and
cyclodextrins, or kojic acid included by cyclodextrins,
can be added to the aqueous phase before the said mixing
in an amount as described above.
The cosmetics of thè present invention may be formed
into a cream, which may be prepared as follows: Into
purified water is added hydrophilic ingredients, for
example, moisturizers such as glycerol and sorbitol, to
form an agueous phase. An oil phase is prepared by
adding olephilic ingredients, such as preservatives~and
surfactants, into an oil, for example, solid oils such
as bees wax, paraffins, microcrystalline wax, ceresine,
higher fatty acids and hardened oils; semisolid oils
such as vaseline, lanolin and glycerides; or liquid
oils, such as sgualane, liquid paraffin and various
ester oils. The thus prepared aqueous and oil phases
are heated to the same temperature, and the latter is
gradually added to the former with gradual stirring and
then emulsified to form a cream. Kojic acid and
cyclodextrins, or kojic acid included by cyclodextrins,
can be added ~to said a~ueous phase in an amount as
defined above.
The cosmetics of the present invention may also be
utilized in the form of an emulsion or a milky lotion.
In this case, the cosmetics of the invention may be
prepared in accordance with the following method: Into
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puriied water are added a moisturizer, such as
glycerol, a pH adjuster, such as an acid and an alkali,
and the like, and the resulting mixture is heated with
stirring. Thereafter, ethanol is additionally added to
the mixture to obtain an aqueous phase. Oily
ingredients, such as preservatives and surfactants, is
then added into an oil, for example, solid oils such as
bees wax and paraffins; semisolid oils such as vaseline
and lanolin; or liquid oils such as squalane, liquid
paraffins and ester oils; and the resulting mixture is
heated to give an oil phase. The oil phase is then
added into the aqueous phase and subjected to a
preliminary emulsification. Into the thus formed
mixture is added protective colloidal agents, such as
carboxyvinyl polymers and carboxymethyl cellulose, and
the resulting mixture is uniformly emulsi~ied by use of
a homogenizing mixer to form a desired emulsion. Kojic
acid and cyclodextrins, or kojic acid included by
cyclodextrins, may be added to the liquid pnase in
advance to said emulsification in an amount as described
above.
The cosmetics of the invention may also be prepared
~in a pack form, which may be prepared in any manner
- generally utilized for the production of packs. For
example, into purified water are added moisturizers,
such as glycerol, etc., film-forming agents, such as
polyvinyl alcohols and bee gum, and other additives.
The resulting mixture is then subjected to swelling. If
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desired, powders of such materials as kaolin, talc and
zinc oxide may be additionally added to the mixture.
Into ethanol are dissolved perfumes, preservatives, and
the like. The ethanol solution is then mixed with the
swelled product, and the resulting mixture is throughly
kneaded to form a paste or cream. Kojic acid and
cyclodextrins, or kojic acid included by cyclodextrins,
can be added in any step of the above preparation, in an
amount as stated hereinabove.
Preparation examples of included kojic acid, or
kojic acid included by cyclodextrins, which is the
active component in the cosmetics of the present
invention, will be shown hereinbelow.
Preparation Example
Into 0.5 to 4 parts by weight of ~-cyclodextrin is
added 1.5 to 1~ parts by weight o purified water and
stirred slowly. Thereafter, 1 part by weight of kojic
acid is additionally added, and the resulting mixture is
throughly stirred until a uniform dispersion is formed
to give included kojic acid. The thus formed included
kojic acid may be freeze dried.
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Example 1: A cream
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Percents by weiqht
20% included kojic acid 5.0
Bees wax 6.0
Cetanol 5.8
Hydrogenated lanolin 8.0
Squalane 30.0
Glyceryl esters of fatty acids 4.0
Oleophilic glyceryl monostearate 2.0
Polyoxyethylene sorbitan monolaurate 2.0
Propylene glycol 5.0
Perfume Appropriate amount
Preservative Appropriate amount
Antioxidant Appropriate amount
Purified water 37.20
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Example 2: A cream
Percents bY weiqht
~ojic acid 1.0
~-cyclodextrin 4.0
Bees wax ; 6.0
Cetanol 5.8
~ydrogenated lanolin 8.0
Squalane 30.0
Glyceryl esters of fatty acids 4.0
Oleophilic glyceryl monostearate 2.0
` Polyoxyethylene sorbitan monolaurate 2.0
: Perfume Appropriate amount
: Preservative Appropriate amount
Antioxidant Appropriate amount
Purified water 37.20
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Example 3: A milky lotion
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Percents bY weiaht
30% included kojic acid 2.5
Sgualane 5.0
Vaseline 2.0
Bees wax 0.5
Sorbitan sesquioleate 0.8
Polyoxyethylene oleyl ether 1.2
Propylene glycol 5.0
Ethanol 5.0
Carboxyvinyl polymer (1~ aqueous solution)20.0
Potassium hydroxide 0.1
Perfume Appropriate amount
Preservative and antioxidant Appropriate amount
Purified water 57.90
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Example q: A milky lotion
Percents by weiaht
Kojic acid 0.75
~cyclodex~in 1.75
Squalane 5.0
Vaseline 2.0
Bees wax 0.5
Sorbitan sesquioleate 0.8
Polyoxyethylene oleyl ether 1.2
Propylene glycol 5.0
Ethanol 5.0
Carboxyvinyl polymer (1% aqueous solution)20.0
Potassium hydroxide 0.1
Perfume Appropriate amount
Preservative and antioxidant Appropriate amount
Purified water 57.90
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Example 5: A pack
Percents bY weiaht
50% included kojic acid 1.0
Bee gum 5.0
Squalane 2.0
Propylene glycol 5.0
Zinc oxide 10.0
Kaolin 10.0
Ethanol 5.0
Perfume Appropriate amount
Preservative Appropriate amount
Purified water 62.0
Example 6: A pack
Percents bv weiqht
Kojic acid 0.5
cyclodextrin 0.5
Bee gum 5.0
Squalane 2.0
Propylene glycol 5.0
Zinc oxide 10.0
Kaolin 10.0
Ethanol 5.0
Perfume Appropriate amount
Preservative Appropriate amount
Purified water 62.0
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Example 7: A toilet lotion
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_ Percents bv weiqht
40~ included kojic acid 2.0
Citric acid 0.4
Calcium carbonate 0.2
Ethanol 5,0
Propylene glycol 9.0
Purified water 82.4
Perfume and preservative Appropriate amount
Example 8: A toilet lotion
Percents b~ weiqht
Kojic acid 0,5
~-cyclodextrin 1.5
Citric acid 0,4
Calcium carbonate 0.2
Ethanol 5.0
Propylene glycol 9,0
Purified water 82.4
Perfume and preservative Appropriate amount
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Example g: Test for coloring-preventing efects
attainable by the active components of the
invention
(1) Samples
A: A cream prepared in Example 1, incorporated with
5% by weight of 20% included kojic acid (i.e.,
1% by weight as kojic acid)
8: A cream prepared in Example 2, incorporated with
1~ by weight of kojic acid and 4% by weight of
~-cyclodextrin
C: A cream incorporated with 1% by weight of kojic
acid but not incorporated with cyclodextrins
(2) Method of test
The samples, A, B and C were allowed to stand for 2
months at a temperature of 45C, and their lightness
(L), redness (a), yellowness (b) and A E (color
difference) were measured and compared with a control
sample stored at a temperature OL 5C for the same
period of time, using Color Difference Meter Z-1001 DP
produced by Nippon Denshoku Co., Ltd.
(3) Results of the test
Results obtained are shown in Table 1.
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It would be apparent from the results shown in Table
1 that Samples A and B, or cosmetics according to the
present invention, have markedly reduced colorings
compared with Sample C, in which kojic acid alone was
incorporated.
Example 10: Test of decoloring effect in cultured dye-
producing cells
( 1 ) Samples
A: Kojic acid
B: 20% included kojic acid prepared in Preparation
Example
C: Kojic acid and ~-cyclodextrin
D: ~-cyclodextrin
(2) Method of test
The mouse melanoma B16 cells were cultured in the
Eagle's MEM medium containing 10% fetal bovine serum
and:
1) 2.5 mM of kojic acid [Test area A];
2) 2.5 mM (reduced to kojic acid) of 20% included
kojic acid (or kojic acid included by
cyclodextrins at a percentage of 20%) prepared
in the Preparation Example [Test area B];
3) Xojic acid and ~-cyclodextrin each in the same
amount as used in Test area B [Test area C];
4) ~-cyclodextrin in the same amount as that of ~-
cyclodextrin contained in the inclusion compound
; used in Test area B [Test area D]; or
5) Nothing [Test area E].
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- The samples were cultured at 37C for 6 days in an
atmosphere consisting of 5~ of CO2 and 9s% of air, then
treated with tripsin, and subjected to centrifugation
for 5 minutes at 2000 rpm to prepare cell pellets. The
darkness of the thus prepared pellets were compared with
the naked eyes.
(3) Results of test
Test area A showed a moderate fading, compared with
Test area E (control).
Test areas B and C showed fading apparently stronger
than that in Test area A, and the pellets obtained from
these areas were white to light yellow in color.
Test area D showed no fading.
It would be apparent from the above results that the
active components of the present invention, namely
included kojic acid and the combination of kojic acid
- and cyclodextrins, have effects of inhibiting the
formation of melanine dyes, compared with the case where
kojic acid alone was used.
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