JPH07215833A - Skin external preparation - Google Patents

Abstract

PURPOSE:To obtain a safe skin external preparation excellent in stability to oxidation, mitigating skin aging symptoms due to peroxidation of dermal lipids, and causing no skin irritation or skin sensitization. CONSTITUTION:The characteristic of this skin external preparation comprises being formulated with a xanthene-2,7-diol compound of the formula (R is H, an alkyl, an alkenyl or an aryl). It is sufficient that as low as 1-50mug of this compound be formulated in 100g of the skin external preparation. This skin external preparation has the following advantages: increase in its peroxide value does not occur even after stored for a long period (namely, stable to oxidation) and aging symptoms due to dermal lipoperoxide formation caused by ultraviolet radiation or metabolism can be effectively lowered or prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to xanthene-2,7-diols having excellent antioxidative properties, and is excellent in storage stability and capable of preventing or preventing skin aging. Regarding agents.

[0002]

2. Description of the Related Art In many cases, cosmetics and external preparations for skin are prepared by combining various fats and oils and water-soluble raw materials, and usually antioxidants are added to prevent the fats and oils from being oxidized. Butyl hydroxyanisole (BH
A), dibutylhydroxytoluene (BHT), gallic acid derivatives such as propyl gallate, vitamin E and its ester, etc. are used.

Further, as it has become clear that lipids in the skin are peroxidized by active oxygen species generated by ultraviolet rays and metabolism, and that such lipid peroxides are one of the causes of aging of the skin, the active oxygen species are Attempts have been made to prevent the generation of lipid peroxides and prevent skin aging by blending an antioxidative agent that captures the above with cosmetics and skin external preparations.

However, among the conventionally used antioxidants, cosmetics and external preparations for the skin containing BHA, BHT and the like are liable to cause contact dermatitis and skin sensitization is concerned.
On the other hand, gallic acid derivatives and vitamin Es do not have sufficient antioxidative activity, and a skin external preparation containing them has a sufficient effect, especially when it is expected to prevent skin aging due to peroxidation of skin lipids. I couldn't do it.

[0005]

The present invention solves the above-mentioned problems and not only provides a skin external preparation having excellent product stability by preventing rancidity of oils and fats mixed in the external preparation, An object of the present invention is to provide a safe external preparation for skin, which can effectively prevent the aging phenomenon caused by skin peroxidation and has no skin irritation or skin sensitization.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors show effective antioxidant activity in a small amount when compounded in a skin external preparation, and have no unfavorable effects on the skin, Furthermore, an antioxidant that does not adversely affect the stability of the preparation for external use was examined. As a result, a high antioxidant activity was found in the xanthene-2,7-diols represented by the general formula 1, and the present invention was completed.

In the general formula 1, R group is hydrogen, alkyl, alkenyl or aryl group, and hydrogen, lower alkyl group such as methyl, ethyl and isopropyl, phenyl group and the like are preferable.

Xanthan-2,7- used in the present invention
The antioxidant activity of diols is shown below. A linoleic acid micelle system was used as an index of antioxidant properties against oils and fats, and a liposome system was used as an index of antioxidant properties in biological membranes. First, the antioxidant properties in the linoleic acid micelle system were as follows: linoleic acid 1.68 mg (60 mM), polyoxyethylene (20) sorbitan monolaurate (Tween 20) 3.6 g, 0.5M2,2'-Azobis- (2 -amidinoprop
ane) hydrochloride (AAPH) 1ml, water 120ml
Xanthene-2,7-diols (2.0 μmol) were added to the micelle aqueous solution, and the amount of dissolved oxygen was measured using an oxygen electrode, and the oxidation induction time (IP) was calculated from this to evaluate the antioxidant activity. In addition, the antioxidant property in the liposome system is that soybean lecithin 150 mg, AAPH 0.8 mmo
Soybean lecithin liposomes were prepared by adding 1.50 μmol of xanthene-2,7-diols to 120 ml of a 0.1 M aqueous sodium chloride solution, and IP was determined by measuring the dissolved oxygen content by an oxygen electrode in the same manner. The results are shown in Table 1.
Shown in.

[Table 1]

In Table 1, xanthene used in the test
All 2,7-diols (R = hydrogen, methyl, ethyl, isopropyl, phenyl) prolong IP significantly compared to the control without antioxidant and are widely used as antioxidants α
-Compared with the addition of tocopherol or chromanol of formula 2, the effect of IP extension is large.

[Chemical 2]

Next, the cytotoxicity of xanthene-2,7-diols will be shown below. For cytotoxicity, normal human-derived fibroblasts were seeded on a 96-well plate and cultured at 37 ° C for 24 hours, and then the culture medium was changed from fetal bovine serum-containing DMEM medium to high-calcium and high-magnesium MCDB153 medium, and further 37 ° C. After culturing for 24 hours in each sample solution 1
00 μl was added, and contact was performed at 37 ° C. for 1 hour or 6 hours. The sample solution was prepared by dissolving each xanthene-2,7-diol in dimethyl sulfoxide (DMSO) and dispersing this in a high calcium and high magnesium MCDB153 medium. The viability of the cells is measured by MTT (2- (4,5-d
imethyl-2-thiazolyl) -3,5-diphenyltetrazolium bromi
de) Obtained by the reduction method and the half-lethal dose (LD50) was calculated. The LD50 value was 50 μg or 1 at 1 hour contact.
It is as high as 00 μg or more, and shows a higher LD50 value than that of BHT even when contacted for 6 hours. Especially, R = hydrogen xanthene-
With 2,7-diol, the LD50 value was 420 μg, which was high in safety.

[0011]

In the present invention, the xanthene-2,7-diols are added in an extremely small amount of about 1 μg to 50 μg in 100 g of the skin external preparation. The external preparation for skin according to the present invention does not show an increase in peroxide value even when stored for a long period of time, is stable against oxidation, and further, is aged due to lipid peroxidation of skin caused by ultraviolet rays or metabolism. Symptoms can be effectively improved and prevented. The external preparation for skin according to the present invention can also be provided as a cosmetic in various forms for beautifying the skin condition.

[0012]

EXAMPLES The present invention will be described in more detail with reference to Examples. Table 2 shows the formulations of the skin cream according to the examples of the present invention together with comparative examples. In Examples 1, 2, and 3, compounds of R = hydrogen, methyl, and phenyl of xanthene-2,7-diol were compounded as antioxidants, and Comparative Examples 1, 2 and 3 were used.
Are tocopherol acetate and BHT, respectively, as antioxidants
It is a mixture of. These are manufactured as follows. In Table 2, the oil phase components (1) to (7) are mixed, dissolved and homogenized, and heated to 75 ° C. On the other hand, (8), (10) and (12) are mixed, dissolved and heated to 75 ° C., and the above oil phase component is added thereto for preliminary emulsification and then homogenized with a homomixer. After cooling, (9) and (11) are added at 50 ° C.

[Table 2]

In the examples of the present invention, the effect of preventing skin aging symptoms, oxidative stability and skin irritation were examined. The effect of preventing skin aging symptoms was evaluated by actually conducting a use test. In the use test, 20 panelists in their 40s to 60s working daily outdoors were set as one group, and the examples and comparative examples were blindly used in each group for 3 months from May to July. The state of improvement of skin wrinkles, texture, acupuncture and rough skin was observed and evaluated. The improvement of skin wrinkles, texture and rough skin is evaluated by observing the appearance by photographing, and the skin elasticity is evaluated by measuring skin elasticity, and wrinkles are “reduced”, “slightly reduced”, “no change”, “ "Increase", "Good", "Slightly good", "No change", "Aggravated" or "Degraded" for texture and acupuncture, "Improved", "Slightly improved", "No change", "Aggravated" for rough skin It was evaluated in each of 4 stages. The results are shown in Table 3 by the number of panelists who obtained each evaluation.

[Table 3]

The oxidative stability is determined by the AOM method (Active oxy
gen method) and evaluated as “◎; very stable”,
It was expressed in four stages: "○; almost stable", "△; somewhat unstable", and "x;unstable". Skin irritation is 30 for each sample
A closed patch test was conducted for 48 hours using a well-known panel, and the results were evaluated according to the criteria shown in Table 4 and 3
It was represented by the average value of the skin irritation index of 0 persons. The results of these tests are summarized in Table 3.

[Table 4]

As is clear from Table 3, in each of the examples of the present invention, the addition of a very small amount of xanthene-2,7-diol showed good oxidative stability and was excellent for the skin. There is a palliative effect of aging symptoms such as wrinkle reduction, texture and astringency improvement, and rough skin improvement. Also,
The skin irritation index was low, showing good safety as in Comparative Example 1 using tocopherol acetate as an antioxidant. On the other hand, in Comparative Example 1, the oxidative stability is not sufficient and the action of alleviating the aging symptoms of skin is also insufficient. On the other hand, in Comparative Example 2 in which BHT was blended as an antioxidant, oxidative stability was good, but skin irritation was observed, and there were cases in which skin symptoms worsened depending on the panelists.

[0016]

As described in detail above, according to the present invention,
It is possible to provide a skin external preparation that has excellent oxidative stability, is safe without skin irritation and sensitization, and can effectively prevent and improve skin aging caused by peroxidation of skin lipids. It was

Claims (2)

[Claims] 1. An external preparation for skin, which comprises xanthene-2,7-diols represented by the general formula 1. [Chemical 1] 2. The external preparation for skin according to claim 1, wherein the external preparation for skin is a cosmetic.