External preparations containing watercress extract

The present invention relates to external preparations containing a watercress extract which are excellent in the humectant effect and also capable of reducing skin irritation and giving a comfortableness of use even if a calefacient is blended. In particular, the present invention provides the external preparations containing a watercress extract with which one or more members selected from the group consisting of powdered capsicum, capsicum extract, capsicum tincture, capsaicin and nonanoic acid vanillylamide can be blended as calefacients.

TECHNICAL FIELD
 The present invention relates to external preparations containing
 watercress extract giving a comfortableness of application with less
 irritation on the skin. In particular, the present invention relates to
 external preparations containing a solvent extract of watercress having
 the humectant effect on the application site of the said preparations.
 Additionally, even if calefacients are further contained, the preparations
 of the present invention are capable of reducing the uncomfortableness of
 these irritants and giving a comfortableness of use to the user.
 BACKGROUND ART
 Watercress (Nasturtium officinale) is a native European perennial plant
 which since introduced into Japan in the early Meiji era, has produced
 colonies in a clear stream as a naturalized plant, and it is eaten mainly
 as an ornamental accompaniment for Western cooking and as a vegetable for
 salads.
 An attempt at blending various solvent extractions of plants including this
 watercress with external preparations such as cataplasms, ointments etc.
 is disclosed in Japanese Laid-Open Patent Application No. 7-25763. This
 publication describes that the combined use of kojic acid and/or its
 derivative having an inhibitory action on melanin formation and various
 plant extracts, brings about the effect of improving the persistent
 efficacy of kojic acid and/or its derivative while alleviating irritation
 on the skin. Under the present circumstances, however, it is not
 sufficiently examined whether the solvent extract of watercress when
 blended in the external preparations has the humectant effect or any other
 effects.
 In recent years, as the house and office come to be completely furnished
 with air conditioners and by excess use of a soap or detergent, there are
 increasing skin troubles such as rough skin, itching etc. Against such
 symptoms, lotions or ointments containing urea or aloe extract etc. are
 commercially available as external preparations for efficiently
 maintaining the water content of the skin or giving the humectant effect.
 However, no adequate examination has been made of plant extract-blended
 external preparations excellent in the sense of use.
 Meanwhile, calefacients such as powdered capsicum, capsicum extract,
 capsicum tincture, nonanoic acid vanillylamide etc. are known for a long
 time. If these calefacients are applied to the skin, the sense of heat is
 generated at the application site, blood capillaries are expanded to make
 blood circulation active to improve the metabolism of tissues, and
 demonstrate the anti-inflammatory and analgesic effects. Accordingly,
 there appeared the products containing these calefacients in cosmetics to
 utilize these effects or in medical external preparations the purpose of
 treating neuralgia, stiffshoulder, lumbago, rheumatism and so on.
 However, when external preparations containing these calefacients are
 applied to the skin, there is a considerable difference in the degree in
 sense of heat, depending on the age, sex, application site and the
 individual conditions. Further, if the calefacient is contained in a large
 amount, it may cause the uncomfortable symptoms of skin irritation such as
 redness, rashes etc., therefore, it is difficult to determine the optimum
 concentration of the calefacients. Furthermore, if the calefacient is
 blended with plasters, the sense of irritation remains even after removal
 of the plasters, and severe pain is frequently experienced at the time of
 bathing.
 To solve such problems, there is an attempt to give the mild sense of heat
 to the skin by using the herb medicines such as ginger, Japanese pepper
 etc. (see Japanese Patent Publication No. 56,206/1988). The other attempt
 is to relieve the irritation by containing perilla or yellow oak extract
 together with the calefacients (see Japanese Patent Publication No.
 51,126/1988). However, even if these herb ingredients are contained, it
 cannot be said that the effect of reducing skin irritation while keeping
 the sense of heat is sufficient, so there is demand for further
 development.
 Accordingly, in view of these circumstances, the object of the present
 invention is to provide external preparations containing herb ingredients,
 which are excellent in the humectant effect, capable of reducing the
 uncomfortableness of irritation even if calefacients are contained, and
 able to give a comfortableness of use to the user.
 To solve the above mentioned problems, the present inventors extensively
 studied the humectant effect, and skin irritation relieving effect and the
 other effects of said preparations containing the herb ingredients. As a
 result, they found that external preparations containing solvent extract
 of watercress gives humectant to the skin, facilitates the sense of heat
 when calefacients are further contained, and hardly permit the
 calefacients to cause skin pain. Hence, the present inventors arrived at
 the completion of the present invention.
 DISCLOSURE OF THE INVENTION
 Accordingly, the embodiment of the present invention provides external
 preparations containing a solvent extract of watercress.
 Another embodiment of the present invention provides external preparations
 further containing calefacients together with the solvent extract of
 watercress.
 In the said embodiment, the present invention provides external
 preparations wherein the calefacient is one or more members selected from
 the group consisting of powdered capsicum, capsicum extract, capsicum
 tincture, capsaicin and nonanoic acid vanillylamide.
 The preparations of the present invention are more specifically external
 preparations in which the drug form is an aqueous cataplasm, a plaster, an
 ointment, or a lotion.
 The preferred embodiment of the present invention provides the aqueous
 cataplasm preparations for external application wherein the water content
 of the preparations is 30 to 80% by weight relative to the total weight of
 the adhesive gel base of the preparations, and the pH of said adhesive gel
 base is in the range of 3.0 to 9.0.
 BEST MODE FOR CARRYING OUT THE INVENTION
 The solvent extract of watercress used in the external preparations of the
 present invention can be prepared by extracting dried or intact leaves and
 stems of watercress, or intact watercress itself, with a solvent.
 As used herein, the term "solvent" refers to hydrophilic organic solvents
 represented by water; lower alcohol such as methanol and ethanol; and
 polyhydric alcohol such as 1,3-butylene glycol, polyethylene glycol and
 propylene glycol, or mixtures thereof.
 A process for producing said solvent extract of watercress can be done by
 using the following method as the topically example. That is, about 9 kg
 of 50% aqueous solution of 1,3-butylene glycol as the extraction solvent
 is added to 1 kg of the whole watercress or leaves and stems thereof, and
 the mixture is refluxed under heating at 100.degree. C. for 1 hour and
 then cooled, and this solution is filtered to remove off the insoluble
 substances, and 50% aqueous solution of 1,3-butylene glycol is further
 added to the filtrate to adjust the total amount to 10 kg whereby the
 extract is obtained. Alternatively, 1 kg of the whole of watercress or
 leaves and stems thereof is immersed in about 9 kg of 50% aqueous solution
 of 1,3-butylene glycol as the extraction solvent at room temperature for 1
 to 7 days or so, and then the insoluble substances are removed off by
 filtration. Then the additional extraction solvent is added to the
 filtrate to adjust the total amount to 10 kg.
 As the solvent extract of watercress used in the external preparations of
 the present invention, the intact extract (hereinafter referred to as
 "watercress extract") produced by the method described above can be used.
 Furthermore, the dried extract substances obtained from the above
 watercress extract by the conventional techniques such as spray drying,
 freeze-drying etc. may also be used. Such dried extract diluted with
 suitable solvents such as purified water, lower alcohol and polyhydric
 alcohol further can be used for the external preparations of the present
 invention.
 The amount of the solvent extract of watercress in the external
 preparations of the present invention is preferably 0.1 to 30% by weight,
 more preferably 0.5 to 10% by weight, when the watercress extract prepared
 according to the method illustrated above is used.
 In the external preparations of the present invention, the calefacients can
 be contained together with the solvent extract of watercress. Said
 calefacients may be one or more members selected from powdered capsicum,
 capsicum extract, capsicum tincture, capsaicin and nonanoic acid
 vanillylamide. In particular, one or more members of capsicum extract,
 capsicum tincture, and nonanoic acid vanillylamide are preferably
 contained.
 The amount of these calefacients contained in the external preparations of
 the present invention is preferably 0.001 to 5% by weight, more preferably
 0.005 to 3% by weight relative to the total weight of the preparations.
 The external preparations of the present invention with which these
 ingredients are suitably contained may be formulated into forms such as
 salves, cataplasms, liniments, lotions, ointments and plasters.
 Besides those ingredients mentioned above, it is possible to contain
 vitamin E such as tocopherol acetate having promoting action on blood
 circulation; glycyrrhizic acid, dipotassium glycyrrhizinate and
 glycyrrhetic acid having analgesic and anti-inflamation action;
 diphenhydramine and chlorphenyramine maleate having anti-allergy action;
 and further plant extracts such as aloe extract, arnica extract, chamomile
 extract, and perilla extract, to the external preparations of the present
 invention.
 Further, medical drugs frequently used in conventional external
 preparations such as glycol salicylate, methyl salicylate, camphor,
 menthol, peppermint oil, eucalyptus oil, turpentine oil, and so on can
 also be contained.
 The amount of these drugs contained in the external preparations of the
 present invention is preferably 0.01 to 30% by weight, more preferably 0.1
 to 15% by weight based on the total weight of the preparations.
 The external preparations of the present invention suitably containing each
 of these components can be formulated into forms such as salves,
 cataplasms, liniments, lotions, ointments and plasters.
 The base materials for the present preparations may be conventionally used
 ones for manufacturing the external preparations in this technical field.
 For example, in the aqueous cataplasms, one or more water-soluble polymers
 selected from sodium alginate, gum Arabic, gelatin, pullulan, pectin,
 polyvinylpyrrolidone, polyvinyl alcohol, methylcellulose, ethylcellulose,
 sodium carboxymethylcellulose, hydroxyethylcellulose,
 hydroxypropyl-cellulose, polyacrylic acid, sodium polyacrylate, acrylic
 copolymers, maleiq anhydride copolymers and methyl vinyl ether are
 comprised. The amount of these polymers may be vary depending on the
 strength and cooling setting ability of the base materials or on
 workability at the time of manufacturing, but is usually 3 to 30% by
 weight based on the total weight of the adhesive gel base.
 If the ingredients of the aqueous cataplasms base composed of such
 water-soluble polymers are to be cross-linked, the cross-linking agent,
 for example, polyvalent metals such as calcium chloride, magnesium
 chloride, aluminum chloride, aluminum sulfate, magnesium sulfate, calcium
 hydroxide, ferric hydroxide, aluminum hydroxide, calcium phosphate,
 aluminum stearate, magnesium stearate, calcium citrate, aluminum glycinal
 and so on, or polyethylene glycol diglycidyl ether, ethylene glycol
 diglycidyl ether, glycerin diglycidyl ether, triglycerin diglycidyl ether
 etc, can be used. The amount of these cross-linking agents is preferably
 0.001 to 5% by weight, more preferably 0.005 to 3% by weight based on the
 total weight of the adhesive gel base.
 Further, in the base material, it is possible to contain inorganic salts
 such as kaolin, bentonite, titanium oxide, zinc oxide etc. and polyhydric
 alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol,
 propylene glycol, glycerin etc. The amount of these materials is
 preferably 5 to 65% by weight, more preferably 10 to 40% by weight, based
 on the total weight of the adhesive gel base.
 The aqueous cataplasms as one embodiment of the external preparations
 provided by the present invention are water containing ones, and the water
 content of the aqueous cataplasms is desirably 30 to 80% by weight,
 preferably 35 to 75% by weight, more preferably 40 to 60% by weight based
 on the total weight of the adhesive gel base. If the water content is less
 than 30% by weight, the heat-sense effect of the calefacients cannot
 sufficiently be exhibited, whereas the water content exceeds 80% by
 weight, the shape retention of the cataplasms is lost, and as a result the
 adhesive gel base drips or remains at the time of release. Hence, these
 water contents are not preferable.
 The pH value of the aqueous cataplasms is desirably adjusted to 3.0 to 9.0,
 preferably 3.5 to 8, more preferably 4 to 7. If the pH value of the
 adhesive gel base is less than 3.0, skin irritation occurs due to strong
 acidity, while the pH value exceeds 9.0, inconvenient actions such as skin
 corrosion and damage occur, so these pH values are not preferable.
 In the ointments as another embodiment of the external preparations of the
 present invention, white vaseline, yellow vaseline, hydrogenated oil,
 solid paraffin, stearic acid, glycerin monostearate, glycerin
 trimyristate, cetyl alcohol, cetyl myristate, hydrocarbon gel, lanolin,
 polyacrylic acid and metallic salts thereof, cellulose derivatives,
 polyacrylic acid derivatives, polymethacrylic acid derivatives, natural
 gum such as gum Arabic and xanthan gum are used.
 The amount of these materials may be vary depending on types of said
 ointments such as gel ointment, oil ointment and hydrophilic ointment, but
 usually in the range of 0.5 to 90% by weight.
 In the ointments, it is also possible to contain purified water, lower
 alcohol such as ethanol, butanol etc., polyhydric alcohol such as
 glycerin, polyethylene glycol, 1,3-butylene glycol etc., isopropyl
 adipate, liquid paraffin, diethyl sebacate, squalane, squalene, vegetable
 oil, hydrogenated oil etc. The amount of these materials may usually be in
 the range of 1 to 90% by weight.
 Further, it is possible to contain preservatives such as
 parahydroxybenzoate esters etc., antioxidants such as butyl hydroxy
 toluene etc., pH adjustors such as triethanolamine etc., surfactants such
 as glycerin monostearate, polyoxyethylene derivatives, sucrose fatty acid
 esters etc., coloring agent, perfumes etc.
 These ingredients can be contained up to an amount of about 15% by weight
 at the maximum.
 In the ointments of the present invention, the ingredients and the
 watercress solvent extract described above and the calefacients if deemed
 to be necessary, are mixed and formed in a conventional manner into oil
 ointment, hydrophilic ointment, gel ointment, and so on.
 The plasters as further embodiment of the external preparations provided by
 the present invention, can be made by using of adhesives comprising
 synthetic rubber-based self-adhesives such as styrene-isoprene-styrene
 block copolymers, natural rubber-based self-adhesives, hydrogenated
 petroleum resin, rosin, hydrogenated rosin, terpene resin, acrylic
 self-adhesives, silicone-based self-adhesives, polyvinyl alcohol,
 polyvinylpyrrolidone, and so on.
 The amount of the adhesives may be varied in the range of 15 to 80% by
 weight based on the total base adhesive material.
 Further, said plasters may also contain liquid rubber such as polybutene,
 polyisobutylene etc., and softeners such as liquid paraffin, vegetable oil
 and lanolin etc. The amount of this softener may be varied in the range of
 10 to 40% by weight based on the total weight of the base adhesive
 material. Further, it is possible to contain percutaneous absorption
 promoters in said plasters such as fatty acid esters, higher alcohol etc.
 In said plasters, a backing may be laminated on the drug-containing
 self-adhesive layer (base adhesive material). Examples of such backing are
 resin films such as cellulose derivative films, polyethylene terephthalate
 film, nylon film, polyvinyl chloride film, polyethylene film, polyurethane
 film, polyvinylidene chloride film etc., and metallic sheets such as
 aluminum, and these are used alone or as a laminate with non-woven fabric
 etc.
 The plasters of the present invention can be prepared in a usual manner by
 kneading and extending said ingredients, the solvent extract of watercress
 and if necessary the calefacients.
 In the lotions as further additional embodiment of the external
 preparations of the present invention, an aqueous liquid such as normal
 water; purified water; lower alcohol for example ethanol, butanol and so
 on; polyhydric alcohol for example glycerin, propylene glycol,
 1,3-butylene glycol and polyethylene glycol and so on, is used. The amount
 of the aqueous liquid may usually be varied in the range of 50 to 98% by
 weight based on the total weight of the preparations.
 In said lotions, it is also possible to contain gum Arabic, sodium
 alginate, water-soluble cellulose lower alkyl ethers such as
 hydroxypropylcellulose, methylcellulose, hydroxyethylcellulose etc.,
 carboxymethylcellulose and salts thereof, polyacrylic acid and salts
 thereof, suspending agents such as bentonite, surfactants such as glycerin
 monostearate, polyoxyethylene derivatives, sucrose fatty acid esters etc.,
 preservatives such as paraoxybenzoate esters, coloring agent, and perfumes
 etc. These can be contained in an amount of about 15% by weight at the
 maximum.
 The lotions of the present invention can be prepared in a usual manner
 using said ingredients, the solvent extract of watercress and if necessary
 the calefacients.

Capsicum tincture 1.0 g
 Nonanoic acid vanillylamide 0.01 g
 Watercress extract 3.0 g
 Glycol salicylate 1.0 g
 dl-Camphor 1.0 g
 Eucalyptus oil 0.3 g
 Propylene glycol 3.0 g
 Ethanol 60.0 g
 Purified water q.s.
 Total 100.0 g
 Example 9
 According to the formulation shown below, capsicum tincture, watercress
 extract, glycol salicylate, propylene glycol, ethanol and purified water
 were uniformly mixed and dissolved whereby a lotion was obtained.

Capsicum tincture 2.0 g
 Watercress extract 5.0 g
 Methyl salicylate 1.5 g
 dl-Camphor 0.5 g
 1-Menthol 0.5 g
 Carboxylvinyl polymer 1.0 g
 Triethanolamine 0.5 g
 1,3-Butylene glycol 3.0 g
 Ethanol 40.0 g
 Purified water g.s.
 Total 100.0 g
 Example 11
 According to the formulation shown below, capsicum tincture, glycol
 salicylate, dl-camphor, glycerin monostearate and Polysorbate 80 were
 mixed uniformly with hydrogenated rape seed oil molten under heating at
 about 70 .degree. C., then hydrocarbon gel were added under cooling, and
 the mixture was further mixed whereby an ointment was obtained.

Watercress extract 10.0 g
 Glycol salicylate 20.0 g
 dl-Camphor 8.0 g
 Glycerin monostearate 5.0 g
 Polysorbate 80 3.0 g
 Hydrogenated rape seed oil 10.0 g
 Hydrocarbon gel q.s.
 Total 100.0 g
 Example 12
 According to the formulation shown below, nonanoic acid vanillylamide,
 watercress extract, glycol salicylate, dl-camphor, synthetic rubber,
 liquid rubber, and alicyclic saturated hydrocarbon resin were molten under
 heating and uniformly kneaded, then the mixture was extended on a support
 film whereby a plaster was obtained.

Nonanoic acid vanillylamide 0.01 g
 Watercress extract 5.0 g
 Glycol salicylate 5.0 g
 dl-Camphor 2.0 g
 Synthetic rubber 30.0 g
 Polyvinyl alcohol 2.0 g
 Liquid rubber 10.0 g
 Alicyclic saturated hydrocarbon resin 45.99 g
 Total 100.0 g
 Test Example 1
 Test on the Skin Humectant Effect of Contained Watercress Extract
 The aqueous cataplasms in Examples 1 and 2 and Comparative Example 1 were
 applied for 90 minutes on the upper arms of 20 volunteers and the state of
 their skin was evaluated after removal.
 The results are shown in Table 4. The evaluation criteria are as follows.
 The effectiveness in Table 4 is expressed in terms of the proportion of
 volunteers for whom the cataplasms were effective, in which more than "+"
 evaluation criteria is considered to be effective, out of the 20
 volunteers.
 TABLE 4
 Results of the Humectant Effect
 Comparative
 Example 1 Example 2 Example 1
 ++ 1 person 4 persons 0 person
 + 10 persons 11 persons 3 persons
 .+-. 9 persons 5 persons 16 persons
 - 0 person 0 person 1 person
 Effectiveness 55% 75% 15%
 Evaluation criteria:
 ++: moist
 +: slightly moist
 .+-.:no change
 -: redness at the application site
 As is evident from the results shown in Table 4, it is understood that the
 aqueous cataplasms containing the watercress extract are superior in the
 humectant effect to the comparative preparation with which the extract was
 not contained.
 Test Example 2
 Test on the Heat Sense Irritation Effect of Contained Calefacient
 The aqueous cataplasms in Examples 3 to 5 and Comparative Examples 2, 4 and
 5 were applied to the upper arms of 10 volunteers and evaluated for
 heat-sense irritation in functional test.
 The test results are shown in Table 5. The criteria for evaluation of
 heat-sense irritation are divided into the following 6 stage and expressed
 as the average of the 10 volunteers.
 Evaluation criteria:
 5: Very strong pain
 4: Feels pain besides a sense of heat.
 3: Feels a suitable sense of heat.
 2: Feels a weak sense of heat.
 1: Feels a sense of mere application.
 0: Feels cold.
 TABLE 5
 Results of the Heat-Sense Irritation Effect Test
 After After After After After
 10 min. 20 min. 30 min. 60 min. 90 min.
 Example 3 1.1 2.4 3.1 3.3 3.2
 Example 4 1.2 2.6 3.4 3.4 3.4
 Example 5 1.6 3.0 3.5 3.7 3.6
 Comp. Ex. 2 0.4 0.8 1.6 2.2 1.8
 Comp. Ex. 4 1.0 2.4 2.6 2.6 2.4
 Comp. Ex. 5 0.8 2.0 2.3 2.5 2.3
 As is evident from the results shown in Table 5 above, it is understood
 that the aqueous cataplasms of the present invention containing the
 watercress extract are strong in the sense of heat effect as compared with
 the comparative preparations with which the extract was not contained.
 Furthermore, the present aqueous cataplasms give a suitable sense of heat
 and are also superior in the sense of heat effect to even the preparations
 with which Japanese pepper extract or perilla extract was contained.
 Test Example 3
 Skin Irritation Test
 The aqueous cataplasms in Examples 3 to 5, the lotion in Example 9, and the
 aqueous cataplasms in Comparative Examples 2 to 5 were applied for 90
 minutes on the upper arms of 10 volunteers (provided that the cataplasms
 were removed thereafter) and observed for skin irritation (redness etc. at
 application site).
 The results are shown in Table 6. The evaluation criteria are as follows.
 TABLE 6
 Results of Skin Irritation Test
 Example 3 Example 4 Example 5 Example 9
 After After After After After After After After
 30 60 30 60 30 60 30 60
 min. min. min. min. min. min. min. min.
 ++ 0 0 0 0 0 0 0 0
 + 0 0 0 0 0 0 0
 .+-. 0 0 0 0 3 0 2 0
 - 10 10 10 10 7 10 8 10
 Comparative Comparative Comparative Comparative
 Example 2 Example 3 Example 4 Example 5
 After After After After After After After After
 30 60 30 60 30 60 30 60
 min. min. min. min. min. min. min. min.
 ++ 0 0 5 2 0 0 0 0
 + 0 0 2 3 0 0 1 0
 .+-. 2 1 2 4 2 1 2 0
 - 8 9 1 1 8 9 7 10
 Evaluation criteria:
 -: Redness is not observed.
 .+-.: Faint redness is observed at the application site.
 +: Redness is observed over the application site.
 ++: Redness is observed not only over the application site, but also around
 the application site.
 As is evident from the results in Table 6, it is understood that the
 occurrence of skin irritation is low for the aqueous cataplasms or lotion
 of the present invention containing the watercress extract. Also the
 occurrence of skin irritation is low even in the case of the preparation
 in Example 9 with which the calefacient was contained in a large amount.
 The occurrence of skin irritation is slightly inhibited in the case of the
 preparations in the Comparative Examples containing Japanese pepper
 extract or perilla extract, but this inhibition is not so great as that of
 the preparations of the present invention. Therefore, it is understood
 that the preparations of the present invention are superior in the effect
 of inhibiting skin irritation.
 INDUSTRIAL APPLICABILITY
 As described above, the external preparations of the present invention
 containing the solvent extract of watercress is excellent in the humectant
 effect, gives comfortable heat-sense stimulation even if a calefacient was
 further contained, and has the effect of reducing the occurrence of skin
 irritation, as compared to the conventional preparations with which
 Japanese pepper extract or perilla extract was contained.
 Accordingly, the external preparations, giving a comfortableness of heat
 without giving an unconfortableness sense of irritation to the skin while
 being superior in the humectant effect on the skin, is provided by the
 present invention.