COMPOSITIONS FOR EXTERNAL APPLICATION

Abstract: A composition for external application comprising kojic acid or a kojic acid derivative is characterized by formulating 4-(1,1-dimethylethyl) -4′-­ methoxydibenzoylmethane therein. The composition has improved effects of inhibiting formation of erythema and pigmentation caused by ultraviolet rays and preventing stains or freckles due to sunburn and having prevented coloration upon use and is an excellent composition for external application such as cosmetics, topical skin agents, etc.

Description: Background of the Invention Field of the Invention The present invention relates to compositions for external application comprising an effective ingredient kojic acid or a kojic acid derivative which can inhibit erythema or pigmentation on the skin and prevent coloration of compositions for external application upon use. Prior Art Statement As substances for preventing formation of melanin caused on the human skin, kojic acid and a kojic acid derivative are known. Skin coating agents comprising these substances as effective ingredients are also known. For example, there are whitening cosmetics comprising kojic acid as a whitening component (Published Unexamined Japanese Patent Application No. 3538/78 and Published Examined Japanese Patent Application No. 18569/81), whitening cosmetics comprising aliphatic carboxylic acid diesters of kojic acid or aliphatic carboxylic acid mono-esters of kojic acid as whitening components (Published Examined Japanese Patent Application Nos. 60801/86 and 9722/85), whitening cosmetics comprising esters of aromatic acids such as cinnamic acid, benzoic acid, etc. of kojic acid as whitening components (Published Examined Japanese Patent Application No. 10005/85), ointments for preventing formation of melanin comprising kojic acid as an effective ingredient (Published Examined Japanese Patent Application No. 10447/86), etc. Further in order to prevent coloration of kojic acid due to change with passage of time, there are known cosmetics comprising kojic acid having formulated therein 2-hydroxy-benzophenone compounds (Published Unexamined Japanese Patent Application No. 108804/87). As described above, kojic acid and a kojic acid derivative are extremely excellent substances that can inhibit the formation of melanin; the substances are known as skin coating agents such as cosmetics which, in the case of preparing the substances into cosmetics and skin agents for external application and applying to the skin, the substances have excellent effects of whitening and inhibiting the formation of melanin and cause no irritation to the skin. Even though pigmentation such as chloasma or the like is improved by the action of kojic acid, however, pigmentation once cured sometimes reverts to the original state due to the affects of ultraviolet rays when exposed to direct rays of the sun. It is also pointed out that when the skin is exposed to strong outdoor direct rays of the sun in such a state that these agents for external application are applied to the skin, the agents for external application are sometimes colored. Summary of the Invention The present inventor has made extensive investigations with an attempt to obtain compositions for external application comprising kojic acid or a kojic acid derivative as an effective ingredient which can inhibit erythema and pigmentation due to ultraviolet rays of compositions for external application containing kojic acid or a kojic acid derivative, can enhance the effect in preventing stains or freckles caused by sunburn, can prevent coloration upon use and cause no irritation to the human skin upon use of such compositions for external application and as a result, it has been found that by formulating 4-(1,1-dimethylethyl)-4′-methoxydibenzoylmethane in compositions for external application comprising kojic acid or a kojic acid derivative as an effective ingredient, neither erythema nor pigmentation appear on the skin after application of such compositions and coloration upon use can be prevented, even though the skin is exposed to ultraviolet rays and the present invention has been accomplished. Detailed Description of the Invention The composition of the present invention for external application contains kojic acid or a kojic acid derivative which is known as a substance for inhibiting the formation of melanin. Examples of the kojic acid derivative include mono-fatty acid esters of kojic acid, for example, kojic acid monopalmitate, kojic acid monobutyrate, kojic acid mono-caprylate, kojic acid monostearate (disclosed in Published Unexamined Japanese Patent Application No. 77272/81), di-fatty acid esters of kojic acid, for example, kojic acid dipalmitate, kojic acid dibutyrate, kojic acid dioleate, kojic acid distearate (disclosed in Published Unexamined Japanese Patent Application No. 7776/84), kojic acid monocinnamoate, kojic acid monobenzoate (Published Unexamined Japanese Patent Application No. 33207/84), etc. The composition of the present invention for external application is used to mean cosmetics such as a cream, a cosmetic lotion, a pack, powders or the like; in addition thereto, quasi drugs for external application such as an emulsion, a lotion, a liniment, an ointment, etc. These preparations can be obtained by making the effective ingredients described above into preparations in a conventional manner using conventional bases. 4-(1,1-Dimethylethyl)-4'-methoxydibenzoylmethane used for preventing coloration of the composition of the present invention for external application comprising kojic acid or the kojic acid derivative is a sun shielding substance disclosed in FR-A-2 440 933 as well as in Published Examined Japanese Patent Application No. 16258/86 and is commercially available under the trademark of "PARSOL 1789" by GIVAUDAN Co., Ltd. In the present invention, by formulating 0.01 to 5.0% (by weight) of this substance in the composition for external application based on the total amount, erythema and pigmentation of kojic acid or the kojic acid derivative caused by ultraviolet rays can be inhibited, the effect of preventing stains or freckles due to sunburn can be enhanced and the composition for external application can prevent coloration upon use. The composition of the present invention for external application may also appropriately contain, in addition to 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane, known UV absorbents such as benzophenone compounds, for example, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzo-phenone-5-sulfonic acid, 2,2′,4,4′-tetrahydroxybenzophenone, etc.; UV absorbents such as phenyl salicylate, ethyl p-aminobenzoate, ethyl urocaniate, 2-(2-hydroxy-5-methylphenyl)benzo-triazole, isopropyl p-methoxycinnamate, 2-ethylhexyl p-methoxy-cinnamate, etc.; UV absorbents from plant extracts such as aloe extract, scutellaria root extract, shear butter, γ-orizanol, soybean oil, etc. to enhance the effect of the present invention. The present invention will be described in more detail with reference to the examples below but is not deemed to be limited thereto. Further, anionic substances such as sodium N-lauroyl-L-glutamate, sodium dl-pyrrolidonecarboxylate, etc.; cationic substances such as stearyl chloride trimethylammonium, cetyl chloride trimethylammonium, etc.; antioxidants such as nicotinic amide, nicotinic acid, natural vitamin E, etc. may also be added to the composition. Next, examples of the present invention and test examples on inhibiting erythema and pigmentation on the skin as well as prevention of coloration of the composition for external application are given below. Example 1 (cosmetic lotion) A mixture of 1.00g of polyoxyethylene-hardened castor oil (60 E.O), a trace amount of fragrance, 15.00g of ethanol and 0.10g of ethyl p-oxybenzoate was homogeneously stirred to dissolve them. Separately, 0.10g of citric acid, 0.30g of sodium citrate, 0.50g of sodium N-lauroyl-L-glutamate, 4.00g of 1,3-butylene glycol, 0.50g of kojic acid, 0.50g of 4-(1,1-dimethylethyl)-4′-methoxydibenzoylmethane and 5.00g of aloe extract as well as purified water to make the whole 100g were homogeneously stirred to dissolve them. The former solution was added to the latter solution and mixed to make a cosmetic lotion. Example 2 (emulsion) A mixture of 0.50g of polyoxyethylene-behenyl ether oil (20 E.O), 1.00g of tetraoleate polyoxyethylene sorbitol (60 E.O), 1.00g of oleophilic glycerin monostearate, 0.50g of stearic acid, 0.50g of behenyl alcohol, 1.00g of avocado oil, 0.02g of natural vitamin E, 0.20g of ethyl p-oxybenzoate and 1.00g of 4-(1,1-dimethylethyl)-4′-methoxydibenzoylmethane was heated to dissolve them. Separately, 0.50g of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 5.00g of 1,3-butylene glycol, 0.10g of carboxyvinyl polymer, 0.50g of sodium N-lauroyl-L-glutamate and 50g of purified water were heated to dissolve them. The latter solution was added to the former solution. The mixture was stirred, emulsified and cooled. To the thus obtained emulsion were added 0.50g of kojic acid, a trace amount of fragrance and purified water to make the whole 100g. The mixture was stirred and mixed to make an emulsion. Example 3 (cream) Two grams of monostearate polyoxyethylene glycol (40 E.O.), 5.00g of self emulsion type glycerin monostearate, 5.00g of stearic acid, 1.00g of behenyl alcohol, 10.00g of liquid paraffin, 10.00g of glyceryl trioctanoate, 0.20g of ethyl p-oxybenzoate and 0.50g of 4-(1,1-dimethylethyl)-4′-methoxy-dibenzoylmethane were heated to dissolve them. Separately purified water was added to 5.00g of 1,3-butylene glycol to make the whole 100g. The mixture was heated to dissolve. The latter was added to the former followed by stirring, emulsifying and cooling. To the thus obtained emulsion were added 1.00g of kojic acid, a trace amount of fragrance and 8.00g of purified water. The mixture was stirred and mixed to make a cream. Example 4 (cream) One gram of monostearate polyoxyethylene sorbitan (60 E.O.), 1.50g of tetraoleate polyoxyethylene sorbitol (60 E.O), 1.50g of self emulsion type glycerin monostearate, 2.00g of white bees wax, 2.00g of paraffin, 3.00g of stearic acid, 3.00g of behenyl alcohol, 12.00g of shear butter, 0.04g of natural vitamin E, 0.10g of methylpolysiloxane, 0.20g of ethyl p-oxybenzoate, 1.00g of 4-(1,1-dimethylethyl)-4′-methoxy-dibenzoylmethane, 1.00g of 2-ethylhexyl p-methoxycinnamate and 5.00g of liquid paraffin were heated to dissolve them. Separately purified water was added to 5.00g of 1,3-butylene glycol, 0.30g of citric acid and 0.50g of sodium N-lauroyl-L-glutamate to make the whole 100g. The mixture was heated to dissolve. The latter was added to the former followed by stirring, emulsifying and cooling. To the thus obtained emulsion were added 2.00g of kojic acid and a trace amount of fragrance. The mixture was stirred and mixed to make a cream. Example 5 (pack) One gram of polyoxyethylene behenyl ether (20 E.O), 2.00g of tetraoleate polyoxyethylene sorbitol (40 E.O), 2.00g of oleophilic glycerin monostearate, 3.00g of behenyl alcohol, 25.00g of squalane, 10.00g of glycerin octanoate, 0.04 g of natural vitamin E, 0.20g of ethyl p-oxybenzoate and 0.50g of 4-(1,1-dimethylethyl)-4′-methoxydibenzoylmethane were heated to dissolve them. Separately 5.00g of 1,3-butylene glycol, 1.50g of sodium dl-pyrrolidonecarboxylate and 50g of purified water were heated to dissolve. The latter was added to the former followed by stirring, emulsifying and cooling. To the thus obtained emulsion were added 0.04g of citric acid, 1.00g of kojic acid and a trace amount of fragrance. Water was added thereto to make the whole 100g and make a pack. Example 6 (powder) Maltitol, 96.0g, 1.0g of octyldodecyl myristate, 2.0g of kojic acid, 1.0g of 4-(1,1-dimethylethyl)-4′-methoxydibenzoyl-methane and a trace amount of fragrance were homogeneously stirred and mixed to powders. Test Example 1 (test on prevention of erythema and pigmentation) (1) Test sample a) A mixture of 2.00g of polyoxyethylene glycol monostearate (4.0 E.D), 5.00g of white emulsion type glycerin monostearate, 5.00g of stearic acid, 1.00g of behenyl alcohol, 10.00g of liquid paraffin, 10.00g of glyceryl trioctanoate and 0.20g of ethyl p-oxybenzoate was heated to dissolve them. Separately, purified water was added to 5.00g of 1,3-butylene glycol to make the whole 100g. The mixture was heated to dissolve them. The latter solution was added to the former solution. The mixture was stirred, emulsified and cooled. To the thus obtained emulsion were added a trace amount of fragrance and 8.00g of purified water. The mixture was stirred and mixed to make a cream (control). b) Cream obtained by formulating 1g of kojic acid in the test sample a) in Test Example 1 (control) c) Cream obtained by formulating 0.5g of 4-(1,1-dimethyl-ethyl)-4'-methoxydibenzoylmethane in the test sample b) in Test Example 1 (composition of the present invention for external application) (2) Method Three regions A, B and C of 2 x 2cm each were provided around the center of the inner side of the left upper arm of persons tested (46 healthy female volunteers). An aluminum foil was set on the arm so as to expose the regions to be tested to ultraviolet rays and, two each of FL20S.BLB lamps and FL20S.E-30 lamps manufactured by Toshiba Corporation were simultaneously irradiated at a distance of 10cm 3 times every day in 0.8 J/cm²/time/day (0.8 x 10⁻⁷ erg/cm²/time/day). The test regions were thoroughly washed with hot water prior to the test. Each test sample was applied to each region 3 times (morning, noon and evening) daily. (3) Evaluation Erythema was visually observed 3 days after the initiation of the test and pigmentation 7 and 21 days after, as compared to the control a), respectively, and the results were evaluated by 4 stages. Points No difference - Slightly thin + Obviously thin ++ Markedly thin +++ (4) Results 1) Erythema (3 days after) Sample b) Case Number (%) Sample c) Case Number (%) No difference 6 (13.0) 0 (0.0) Slightly thin 7 (15.1) 9 (19.6) Obviously thin 25 (54.5) 26 (56.5) Markedly thin 8 (17.4) 11 (23.9) Total 46 (100.0) 46 (100.0) Sample b) (control) inhibited erythema (cases with points being obviously thin or better are 71.9%) as compared to Sample a) (control) but Sample c) (composition of the present invention for external application) inhibited erythema more than Sample b) (cases with points being obviously thin or better are 80.4%). 2) Pigmentation 7 Days after: Sample b) Case Number (%) Sample c) Case Number (%) No difference 7 (15.2) 1 (2.2) Slightly thin 6 (13.0) 7 (15.2) Obviously thin 24 (52.2) 27 (58.7) Markedly thin 9 (19.6) 11 (23.9) Total 46 (100.0) 46 (100.0) 21 Days after: Sample b) Case Number (%) Sample c) Case Number (%) No difference 5 (10.9) 1 (2.2) Slightly thin 12 (26.1) 6 (13.0) Obviously thin 26 (56.5) 30 (65.2) Markedly thin 3 (6.5) 9 (19.6) Total 46 (100.0) 46 (100.0) Sample b) inhibited induction of pigmentation in both tests 7 and 21 days after (cases with points being obviously thin or better are 71.8% and 63.0%, respectively) as compared to Sample a) but Sample C provided better results than Sample b) in both tests (cases with points being obviously thin or better are 82.6% and 84.8%, respectively). Test Example 2 Sun Exposure Test (1) Method Three regions of 5 x 5 cm each were provided on the lower scapular regions of 10 normal male volunteers. Sample a), Sample b) and Sample c) in Test Example 2 were applied to the regions in a dose of about 25mg, respectively. The upper half back part of the body including each test region was exposed to direct rays of sun for 5 hours. Change of each test sample in coloration was observed with passage of time. Conditions in this case were as follows. Place: ground owned by this company (Fukuoka Prefecture) Weather: fine Temperature: 24.5 - 29.0°C Intensity of ultraviolet rays: 365 nm 4.01-4.95mW/cm² 305 nm 0.28-0.38mW/cm² Time for exposure: 10:30 - 15:30 (2) Results 1 Hr. After 3 Hrs. After 5 Hrs. After Sample a) no change slightly some or less Sample b) no change slightly yellowish some or less yellowish Sample c) no change no change no change In Sample a) and Sample b), change in color hue was noted but in Sample c), no change was noted at all. The present invention is extremely useful in providing excellent compositions for external application having effects of inhibiting erythema and pigmentation on the skin caused by ultraviolet rays after use that could not be solved by conventional kojic acid-containing compositions for external application and thereby preventing stains or freckles due to sunburn and at the same time, preventing coloration of the applied compositions for external application occurred when exposed to strong outdoor direct rays of sun after applying to the skin.

Claims: A composition for external application having improved effects of inhibiting formation of erythema and pigmentation caused by ultraviolet rays and preventing stains or freckles due to sunburn and which prevents coloration upon use, comprising kojic acid or a kojic acid derivative, the composition characterized by formulating 0.01 to 5.0 % by weight of the total composition of 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane. A composition as claimed in claim 1 wherein said kojic acid derivative is a mono-fatty acid ester of kojic acid selected from kojic acid monopalmitate, kojic acid monobutyrate, kojic acid monocaprylate and kojic acid monostearate or a di-fatty acid ester of kojic acid selected from kojic acid dipalmitate, kojic acid dibutyrate, kojic acid dioleate and kojic acid distearate; kojic acid monocinnamoate or kojic acid monobenzoate. A composition as claimed in claim 1 wherein a UV absorbent is further contained. A composition as claimed in claim 3 wherein said UV absorbent is a benzophenone compound selected from 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and 2,2',4,4'-tetrahydroxybenzophenone; phenyl salicylate, ethyl p-aminobenzoate, ethyl urocaniate, 2-(2-hydroxy-5-methyl-phenyl)benzotriazole, isopropyl p-methoxycinnamate, 2-ethylhexyl p-methoxycinnamate; or a plant extract selected from an aloe extract, a scutellaria root extract, shear butter, γ-orizanol and soybean oil. A composition as claimed in claim 1 wherein an anionic substance selected from sodium N-lauroyl-L-glutamate and sodium dl-pyrrolidonecarboxylate; a cationic substance selected from stearyl chloride trimethylammonium and cetyl chloride trimethylammonium; or an antioxidant selected from nicotinic amide, nicotinic acid and natural vitamin E may also be formulated.

Inventors: HARA, KENICHI
Applicants: SANSHO SEIYAKU CO., LTD.
Application year: 1987
Main classification: A61K7
IPC codes: A61K8, A61Q17, A61Q1, A61Q19, A61Q5