JP7838077B2 - liquid oral composition - Google Patents

Description

This invention relates to a liquid oral composition.

As a technique for incorporating copper compounds into oral preparations, there are the examples described in Patent Document 1 (Japanese Patent Publication No. 11-269073) and Patent Document 2 (Japanese Patent Publication No. 2021-91654).

Patent Document 1 states that copper chlorophyllin is a compound obtained by replacing a magnesium atom in the chlorophyllin molecule with a copper atom, and that chlorophyllin is effective as a pharmaceutical for preventing bad breath and treating wounds, and has been incorporated into many products (paragraph 0002). The same document describes a preparation containing a salt of copper chlorophyllin and an acid (Claim 1), and a method for preventing tongue discoloration by the salt of copper chlorophyllin by adding an acid (Claim 7). The same document also describes observations of the degree of tongue discoloration for a granular preparation containing copper chlorophyllin potassium and citric acid (Example 1), and a chewable tablet containing copper chlorophyllin potassium and citric acid (Example 2, Table 1, etc.).

Patent Document 2 describes that water-soluble polyvalent metal salts such as copper salts are medicinal ingredients that can be incorporated into toothpaste compositions, and that such ingredients have effects such as suppressing hypersensitivity, suppressing bad breath, and tightening gums, and are effective in preventing or suppressing oral diseases (paragraph 0002). The same document describes a toothpaste composition containing water-soluble polyvalent metal salts, which is easy to apply to a toothbrush, has excellent moldability, and has excellent discharge properties from the storage container even after storage (paragraph 0001), and describes a toothpaste composition containing one or more water-soluble polyvalent metal salts selected from water-soluble aluminum salts, water-soluble copper salts, and water-soluble zinc salts, xanthan gum, and a cationic polymer compound (claim 1).

Japanese Patent Application Publication No. 11-269073 Japanese Patent Publication No. 2021-91654

On the other hand, the present inventors have found that when water-soluble copper salts such as copper gluconate are incorporated into a liquid oral composition, discoloration may occur in the oral cavity, for example, on the tongue, oral mucosa, or teeth.

Therefore, the present invention provides a technique for suppressing oral discoloration when applying a liquid oral composition containing a water-soluble copper salt.

The inventors diligently investigated the cause of discoloration when using a liquid oral composition containing a water-soluble copper salt. As a result, they found that one of the causes is the reaction between the water-soluble copper salt in the liquid oral composition and components present in the oral cavity. For example, it was found that when water-soluble copper salt and polyphenols (e.g., tannic acid) contained in tea coexist, a brown precipitate may form.

Therefore, the inventors further investigated how to suppress discoloration caused by water-soluble copper salts in the liquid oral composition and components present in the oral cavity, and discovered that incorporating water-soluble aluminum salts into the liquid oral composition is effective, thus completing the present invention.

According to the present invention, the following liquid oral composition and method for inhibiting tooth discoloration are provided.
[1] A liquid oral composition containing a water-soluble copper salt and a water-soluble aluminum salt.
[2] The liquid oral composition according to [1], wherein the water-soluble copper salt is one or more selected from the group consisting of copper gluconate, copper sulfate, copper citrate, copper chlorophyll, and sodium copper chlorophyllin.
[3] The liquid oral composition according to [1] or [2], wherein the water-soluble copper salt is copper gluconate.
[4] The liquid oral composition according to any one of [1] to [3], wherein the water-soluble aluminum salt is an aluminum salt of an organic acid.
[5] The liquid oral composition according to any one of [1] to [3], wherein the water-soluble aluminum salt is one or more selected from the group consisting of aluminum lactate, potassium aluminum sulfate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum benzoate, and allantoin chlorohydroxyaluminum.
[6] The liquid oral composition according to any one of [1] to [5], wherein the water-soluble aluminum salt is aluminum lactate.
[7] A liquid oral composition according to any one of [1] to [6], containing copper gluconate and aluminum lactate.
[8] The copper gluconate content is 0.01% by mass or more and 0.2% by mass or less relative to the entire liquid oral composition.
The liquid oral composition according to [7], wherein the content of aluminum lactate is 0.01% by mass or more and 3% by mass or less of the entire liquid oral composition.
[9] The liquid oral composition according to any one of [1] to [8], wherein the content of the water-soluble aluminum salt relative to the content of the water-soluble copper salt in the liquid oral composition is 0.25 or more and 300 or less by mass ratio.
[10] A liquid oral composition according to any one of [1] to [9], which is a tongue discoloration inhibitor.
[11] A liquid oral composition according to any one of [1] to [9], which is an oral mucosal discoloration inhibitor.
[12] A mouthwash, a liquid oral composition according to any one of [1] to [11].
[13] A method for inhibiting tooth discoloration, comprising applying a composition containing a water-soluble copper salt and a water-soluble aluminum salt to the oral cavity.

Furthermore, any combination of these configurations, as well as conversions of the expressions of the present invention between methods, apparatuses, etc., are also valid embodiments of the present invention.
For example, according to the present invention, a toothpaste containing a water-soluble copper salt and a water-soluble aluminum salt can also be provided.

According to the present invention, it is possible to suppress discoloration in the oral cavity when applying a liquid oral composition containing a water-soluble copper salt.

Embodiments of the present invention will be described below. In this embodiment, the composition may contain each component individually or in combination of two or more components.
In this specification, the "～" symbol indicating a numerical range represents "greater than or equal to" and "less than or equal to," and includes both of the numbers at either end.

In this embodiment, the composition is applied to the oral cavity, and specifically, it is a liquid oral composition.

(Liquid oral composition)
In this embodiment, the liquid oral composition contains a water-soluble copper salt and a water-soluble aluminum salt.
The following explains each component.

(Water-soluble copper salt)
Water-soluble copper salts specifically refer to inorganic or organic copper salts that are water-soluble. Water-soluble copper salts may be either anhydrous or hydrated. Any water-soluble copper salt used in pharmaceuticals, food products, or cosmetics is acceptable.
Furthermore, as a water-soluble copper salt, from the viewpoint of improving the combined effect with water-soluble aluminum salts, for example, one or more selected from the group consisting of copper gluconate, copper sulfate, copper citrate, copper chlorophyll, and copper chlorophyllin sodium can be used. From the viewpoint of further improving the combined effect of the water-soluble copper salt, such as the effect of suppressing bad breath, the water-soluble copper salt preferably contains at least one of copper gluconate and copper sulfate, and more preferably copper gluconate.
As a water-soluble copper salt, commercially available products can be used, for example.

From the viewpoint of further improving the effects of the water-soluble copper salt in the liquid oral composition, such as the effect of suppressing bad breath, the content of the water-soluble copper salt is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.03% by mass or more, and even more preferably 0.08% by mass or more, relative to the total liquid oral composition.
Furthermore, from the viewpoint of improving the effect of suppressing discoloration in the oral cavity, the content of water-soluble copper salt in the liquid oral composition is preferably 10% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, and even more preferably 0.2% by mass or less, relative to the total liquid oral composition.

Furthermore, from the viewpoint of further improving the effects of the water-soluble copper salt in the liquid oral composition, such as the effect of suppressing bad breath, the amount of copper is preferably 0.001% by mass or more, and more preferably 0.01% by mass or more.
Furthermore, from the viewpoint of improving the effect of suppressing discoloration in the oral cavity, the content of water-soluble copper salt in the liquid oral composition is preferably 0.06% by mass or less, and more preferably 0.03% by mass or less, as the amount of copper added.

(Water-soluble aluminum salt)
Water-soluble aluminum salts specifically refer to water-soluble inorganic or organic acid salts of aluminum. Water-soluble aluminum salts may be in either anhydrous or hydrated form. Any water-soluble aluminum salt used in pharmaceuticals, food products, or cosmetics is acceptable.

From the viewpoint of more stably suppressing oral discoloration, the water-soluble aluminum salt is preferably one or more selected from the group consisting of aluminum lactate, potassium aluminum sulfate, aluminum sulfate, aluminum nitrate, aluminum chloride (e.g., aluminum chloride hexahydrate), aluminum benzoate, and allantoin chlorohydroxyaluminum, and more preferably at least one selected from the group consisting of aluminum lactate and aluminum chloride.

From the viewpoint of more stably suppressing oral discoloration, the water-soluble aluminum salt is preferably an aluminum salt of an organic acid.
From a similar viewpoint, the aluminum salt of the organic acid is, for example, one or more selected from the group consisting of aluminum lactate, aluminum citrate, and aluminum benzoate, and is preferably aluminum lactate.

From the viewpoint of improving the effect of suppressing discoloration in the oral cavity, the content of water-soluble aluminum salt in the liquid oral composition is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.06% by mass or more, even more preferably 0.08% by mass or more, and even more preferably 0.1% by mass or more, relative to the total liquid oral composition.
Furthermore, from the viewpoint of improving the effect of suppressing discoloration in the oral cavity and suppressing metallic taste, the content of water-soluble aluminum salt in the liquid oral composition is preferably 5% by mass or less, more preferably 3.5% by mass or less, even more preferably 3% by mass or less, and even more preferably 1.5% by mass or less, based on the total liquid oral composition.

Furthermore, from the viewpoint of improving the effect of suppressing discoloration in the oral cavity, the content of water-soluble aluminum salt in the liquid oral composition is preferably 0.002% by mass or more, and more preferably 0.005% by mass or more.
Furthermore, from the viewpoint of improving the effect of suppressing discoloration in the oral cavity and suppressing metallic taste, the content of water-soluble aluminum salt in the liquid oral composition may be, for example, 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.2% by mass or less, as the amount of aluminum blended.

Furthermore, the ratio of water-soluble aluminum salt to water-soluble copper salt in the liquid oral composition (water-soluble aluminum salt/water-soluble copper salt) is preferably 0.25 or more by mass, and more preferably 0.5 or more, from the viewpoint of improving the effect of suppressing discoloration in the oral cavity.
Furthermore, from the viewpoint of suppressing metallic taste, the above mass ratio (water-soluble aluminum salt/water-soluble copper salt) is preferably 300 or less, more preferably 100 or less, and even more preferably 50 or less.

In this embodiment, the liquid oral composition preferably contains copper gluconate and aluminum lactate, from the viewpoint of more stably suppressing discoloration in the oral cavity.
In this case, the copper gluconate content is preferably 0.01% by mass or more and 0.2% by mass or less relative to the entire liquid oral composition, and the aluminum lactate content is preferably 0.01% by mass or more and 3% by mass or less relative to the entire liquid oral composition.

(water)
Liquid oral compositions specifically include water.
The water content in the liquid oral composition can be, for example, the remainder after removing components other than water from the liquid oral composition.
Furthermore, the water content in the liquid oral composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and also preferably 99.99% by mass or less, more preferably 99.989% by mass or less, and even more preferably 99.90% by mass or less, relative to the total liquid oral composition.

(Other ingredients)
Compositions such as liquid oral compositions may contain components other than those described above, as long as they do not impair the effects of the present invention.
Examples of such ingredients include medicinal ingredients, abrasives, binders, viscosity modifiers, surfactants, flavoring agents, preservatives, fragrances, colorants, pH adjusters, solvents, solubilizers, bases, detergents, adsorbents, etc., which can be appropriately selected depending on the dosage form, etc. Specific examples of additive ingredients are shown below, but the ingredients that can be included are not limited to these.

Examples of medicinal ingredients include one or more selected from the group consisting of antiseptics, anti-inflammatory agents, blood circulation promoters, tartar buildup inhibitors, stain removers, desensitizing agents, vitamins, and plaque-degrading enzymes. These medicinal ingredients are not limited to those that can be used in pharmaceuticals, etc.

Among the medicinal ingredients, examples of antiseptics include one or more selected from the group consisting of isopropylmethylphenol, cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride, hinokitiol, chlorhexidine hydrochloride, alkyldiaminoethylglycine hydrochloride, sodium lauroyl sarcosinate, and triclosan.

Examples of anti-inflammatory agents include one or more selected from the group consisting of β-glycyrrhetinic acid, glycyrrhetinic acid, glycyrrhizic acid, diammonium glycyrrhizinate, disodium glycyrrhizinate, trisodium glycyrrhizinate, dipotassium glycyrrhizinate, monoammonium glycyrrhizinate, tranexamic acid, ε-aminocaproic acid, sodium azulene sulfonate hydrate, allantoin, allantoin dihydroxyaluminum, epidihydrocholesterol, dihydrocholesterol, and lysozyme hydrochloride.

Examples of blood circulation-promoting agents include sodium chloride.

Examples of tartar buildup inhibitors include one or more selected from the group consisting of zeolite, disodium hydrogen phosphate, disodium dihydrogen pyrophosphate, sodium pyrophosphate, anhydrous sodium pyrophosphate, tetrasodium pyrophosphate (anhydrous), disodium monohydrogen phosphate, sodium hydrogen phosphate hydrate, disodium hydrogen phosphate (crystalline), trisodium phosphate, and sodium polyphosphate.

Examples of stain removers include one or more selected from the group consisting of macrogol (such as macrogol 200, macrogol 300, macrogol 400, macrogol 600, macrogol 1000, macrogol 1500, macrogol 1540, macrogol 4000, macrogol 6000, macrogol 20000), sodium polyphosphate, and polyvinylpyrrolidone.

Examples of hypersensitivity inhibitors include at least one selected from the group consisting of potassium nitrate and aluminum salts other than water-soluble aluminum salts.

Examples of vitamin supplements include one or more selected from the group consisting of ascorbic acid, L-ascorbic acid, sodium ascorbate, sodium L-ascorbate, pyridoxine hydrochloride, DL-α-tocopherol acetate, tocopherol acetate, dl-α-tocopherol nicotinate, and tocopherol nicotinate.

Examples of plaque-degrading enzymes include dextranase.

Examples of abrasives include silica-based abrasives such as anhydrous silicic acid, silica (crystalline silica or amorphous silica), silica gel, and aluminosilicate; and one or more selected from the group consisting of zeolite, anhydrous calcium hydrogen phosphate, calcium hydrogen phosphate dihydrate, calcium pyrophosphate, calcium carbonate, aluminum hydroxide, alumina, magnesium carbonate, trimagnesium phosphate, zirconium silicate, tricalcium phosphate, hydroxyapatite, tetracalcium phosphate, and synthetic resin-based abrasives.

Examples of binders include one or more selected from the group consisting of organic binders such as pullulan, gelatin, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, sodium carboxymethylcellulose, carrageenan, sodium alginate, xanthan gum, sodium polyacrylate, gum arabic, guar gum, locust bean gum, polyvinyl alcohol, polyvinylpyrrolidone, and carboxyvinyl polymer, as well as thickening anhydrous silicic acid and bentonite.

The viscosity agent can be any substance commercially available as a raw material for pharmaceuticals, food, or cosmetics. For example, one or more substances selected from the group consisting of polyhydric alcohols, and more specifically, sorbitol, glycerin, concentrated glycerin, ethylene glycol, propylene glycol, 1,3-butylene glycol, propanediol (1,3-propanediol), polyethylene glycol, polypropylene glycol, xylitol, maltitol, lactitol, trehalose, sodium hyaluronate, and hydrolyzed collagen.

Examples of surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, and preferably one or more selected from the group consisting of anionic surfactants, nonionic surfactants, and amphoteric surfactants.

Examples of anionic surfactants include one or more selected from the group consisting of N-acyl amino acid salts, α-olefin sulfonates, N-acyl sulfonates, alkyl sulfates (e.g., sodium lauryl sulfate), and sulfates of glycerol fatty acid esters.
Examples of nonionic surfactants include one or more selected from the group consisting of polyoxyethylene alkyl ethers, polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene hydrogenated castor oil, polyoxyethylene ethers of glycerin esters, sucrose fatty acid esters, alkylolamides, and glycerin fatty acid esters.
Examples of amphoteric surfactants include one or more selected from the group consisting of alkyl betaine surfactants, amine oxide surfactants, and imidazolinium betaine surfactants. Specific examples include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine and coconut oil fatty acid amide alkyl betaine.

Examples of flavoring agents include one or more selected from the group consisting of L-sodium glutamate, saccharin, sodium saccharin, disodium glycyrrhizinate, trisodium glycyrrhizinate, sucrose, glucose, fructose, lactose, honey, aspartame, stevia, sucralose, xylitol, inositol, D-sorbitol, D-mannitol, arabitol, raffinose, lactulose, lactitol, erythritol, reduced palatinose, palatinose, palatinose, acesulfame K, maltose, maltosyltrehalose or maltitol, neohesperidin dihydrochalcone, perillartin, p-methoxycinnamicaldehyde, and thaumatin.

Examples of preservatives include benzoates such as sodium benzoate; para-hydroxybenzoic acid esters such as methylparaben, ethylparaben, butylparaben, isopropylparaben, propylparaben, isobutylparaben, and benzylparaben; alcohols such as phenoxyethanol and ethanol; sorbic acid, benzoic acid, dehydroacetic acid, propionic acid and their salts; ethylenediaminetetraacetate; and one or more selected from the group consisting of alkyldiaminoethylglycine hydrochloride.

Examples of fragrances include one or more selected from the group consisting of L-menthol, peppermint, spearmint, fruit flavors, and peppermint oil.

Examples of colorants include natural pigments such as safflower red pigment, gardenia yellow pigment, gardenia blue pigment, perilla pigment, red yeast rice pigment, red cabbage pigment, carrot pigment, hibiscus pigment, cocoa pigment, spirulina blue pigment, and coumarind pigment; legally designated pigments such as Red No. 3, Red No. 104, Red No. 105, Red No. 106, Yellow No. 4, Yellow No. 5, Green No. 3, and Blue No. 1; and one or more selected from the group consisting of riboflavin and titanium dioxide.

Examples of pH adjusting agents include one or more selected from the group consisting of acids and alkalis such as acetic acid, hydrochloric acid, sulfuric acid, nitric acid, citric acid, phosphoric acid, malic acid, gluconic acid, maleic acid, succinic acid, glutamic acid, pyrophosphate, tartaric acid, sodium acetate hydroxide, potassium hydroxide, sodium acetate, sodium carbonate, sodium citrate, sodium hydrogen citrate, phosphoric acid, sodium phosphate, monohydrogen phosphate, dihydrogen dihydrogen phosphate, potassium dihydrogen phosphate, and buffering agents.

In addition to water, mentioned above, other solvents include lower alcohols such as ethanol and propanol.

Solubilizers may be added to promote the dissolution of the above-mentioned additives and active ingredients in water. Examples of such solubilizers include polyhydric alcohols such as propylene glycol, dipropylene glycol, butylene glycol, and polyethylene glycol.

Examples of base materials include sodium bicarbonate.

Examples of cleaning agents include sodium polyphosphate.

Examples of adsorbents include β-cyclodextrin.

Furthermore, in addition to the above-mentioned components, other components suitable for use in oral compositions, such as liquid oral compositions, may be appropriately blended, as long as they do not impair the content of the present invention.

(Liquid formulation)
Furthermore, liquid oral compositions are specifically liquid formulations. Liquid formulations are specifically oral administration formulations.
Specific embodiments of the liquid oral composition include one selected from the group consisting of mouthwash, liquid toothpaste, and oral freshener. From the viewpoint of further improving the effects of the water-soluble copper salt and water-soluble aluminum salt, the liquid oral composition is preferably a mouthwash.

(Manufacturing method)
In this embodiment, the liquid oral composition includes, for example, a step of blending a water-soluble copper salt, a water-soluble aluminum salt, water, and other components as appropriate.

The liquid oral composition obtained in this embodiment contains a water-soluble copper salt and a water-soluble aluminum salt, and therefore can effectively suppress discoloration when applied to the oral cavity, such as staining of the tongue, oral mucosa, or teeth.

The liquid oral composition obtained in this embodiment is suitably used, for example, as a tongue stain inhibitor, an oral mucosa stain inhibitor, or a tooth stain inhibitor.

In this embodiment, the method for suppressing tongue discoloration, the method for suppressing oral mucosal discoloration, and the method for suppressing tooth discoloration all involve applying a composition containing a water-soluble copper salt and a water-soluble aluminum salt to the oral cavity.

The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted.
Examples of reference formats are provided below.
1. A liquid oral composition containing a water-soluble copper salt and a water-soluble aluminum salt.
2. The liquid oral composition according to 1, wherein the water-soluble copper salt is one or more selected from the group consisting of copper gluconate, copper sulfate, copper citrate, copper chlorophyll, and sodium copper chlorophyllin.
3. The liquid oral composition according to 1. or 2., wherein the water-soluble copper salt is copper gluconate.
4. The liquid oral composition according to any one of 1 to 3, wherein the water-soluble aluminum salt is an aluminum salt of an organic acid.
5. The liquid oral composition according to any one of 1 to 3, wherein the water-soluble aluminum salt is one or more selected from the group consisting of aluminum lactate, potassium aluminum sulfate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum benzoate, and allantoin chlorohydroxyaluminum.
6. The liquid oral composition according to any one of 1 to 5, wherein the water-soluble aluminum salt is aluminum lactate.
7. A liquid oral composition according to any one of 1 to 6, containing copper gluconate and aluminum lactate.
8. The copper gluconate content is 0.01% by mass or more and 0.2% by mass or less relative to the entire liquid oral composition.
The liquid oral composition according to 7, wherein the content of aluminum lactate is 0.01% by mass or more and 3% by mass or less of the total liquid oral composition.
9. The liquid oral composition according to any one of 1 to 8, wherein the content of the water-soluble aluminum salt relative to the content of the water-soluble copper salt in the liquid oral composition is 0.25 or more and 300 or less by mass ratio.
10. A liquid oral composition according to any one of 1 to 9, which is a tongue discoloration inhibitor.
11. A liquid oral composition according to any one of 1 to 9, which is an oral mucosal discoloration inhibitor.
12. A liquid oral composition according to any one of 1 to 11, which is a mouthwash.
13. A method for inhibiting tooth discoloration, comprising applying a composition containing a water-soluble copper salt and a water-soluble aluminum salt to the oral cavity.

The embodiment will be described in detail below with reference to examples and comparative examples, but this embodiment is not limited to these examples.

(Example test)
(Examples 1-30, Comparative Examples 1-3)
The ingredients listed in Tables 1 to 4 were mixed to prepare mouthwashes for each example, and evaluated using the method described below. Details of the ingredients listed in each table are shown below.
Copper gluconate (GCu): Manufactured by Fuso Chemical Industries, Ltd. Aluminum lactate (Al lactate): Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Aluminum chloride hexahydrate (Al chloride): Manufactured by Kanto Chemical Co., Ltd. Tannic acid: Manufactured by Nacalai Tesque Corporation

(Evaluation method)
In each example, tannic acid was added to the mouthwash obtained, in an amount equal to 2 mg/mL of the composition. After standing at 37°C for one week, the degree of coloration of the precipitate was visually evaluated compared to a comparative example that contained the same concentration of water-soluble copper salt but no water-soluble aluminum salt. The evaluation criteria are shown below.
++: Marked improvement +: Improvement ±: No change -: Worsening

Tables 1 to 4 show that in each example, discoloration was suppressed when mouthwash and tannic acid were present together.
Furthermore, the compositions obtained in each example had a feel that made them suitable for use as a mouthwash.

This application claims priority based on Japanese Patent Application No. 2022-058491, filed on 31 March 2022, and incorporates all of its disclosures herein.

Claims (12)

A liquid oral composition containing a water-soluble copper salt and a water-soluble aluminum salt ,
The water-soluble copper salt is one or more selected from the group consisting of copper gluconate, copper sulfate, copper citrate, copper chlorophyll, and sodium copper chlorophyllin.
The aforementioned water-soluble aluminum salt is one or more selected from the group consisting of aluminum lactate, potassium aluminum sulfate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum benzoate, and allantoin chlorohydroxyaluminum.
A liquid oral composition wherein the content of the water-soluble aluminum salt relative to the content of the water-soluble copper salt in the liquid oral composition is 60 to 100 by mass ratio . The liquid oral composition according to claim 1 , wherein the water-soluble copper salt is copper gluconate. The liquid oral composition according to claim 1 or 2, wherein the water-soluble aluminum salt is an aluminum salt of an organic acid. The liquid oral composition according to claim 1 or 2, wherein the water-soluble aluminum salt is aluminum lactate. The liquid oral composition according to claim 1 or 2, wherein the content of the water-soluble copper salt in the liquid oral composition is 0.001% by mass or more and 10% by mass or less with respect to the entire liquid oral composition. The liquid oral composition according to claim 1 or 2, wherein the content of the water-soluble aluminum salt in the liquid oral composition is 0.01% by mass or more and 5% by mass or less of the total liquid oral composition. A liquid oral composition according to claim 1 or 2, containing copper gluconate and aluminum lactate. The copper gluconate content is 0.01% by mass or more and 0.2% by mass or less relative to the entire liquid oral composition.
The liquid oral composition according to claim 7, wherein the content of aluminum lactate is 0.01% by mass or more and 3% by mass or less of the total liquid oral composition. A liquid oral composition according to claim 1 or 2, which is a tongue discoloration inhibitor. A liquid oral composition according to claim 1 or 2, which is an oral mucosal discoloration inhibitor. A liquid oral composition according to claim 1 or 2, which is a mouthwash. A method for inhibiting tooth discoloration, comprising applying the liquid oral composition described in claim 1 or 2 to the oral cavity.