Composition, methods for inhibiting microbial growth in oral formulations, and substances for enhancing the antimicrobial effect of quercetin or its glycosides.

Abstract

Invention details;

Description

COMPOSITION, METHOD FOR INHIBITORY OF MICROORGANIZATION BY ORAL COMPOSITION, AND AGENT FOR ENHANCER OF MICROORGANIZATION ACTIVITY OF QUERCETIN OR ITS GLYCOSIDES - Patent application

[0001] The present invention relates to a composition containing L-ergothioneine or a salt thereof and quercetin or a glycoside thereof. The present invention also relates to a method for inhibiting microbial growth using an oral composition. The present invention further relates to an enhancer for the microbial growth inhibitory effect of quercetin or a glycoside thereof.

[0002] It is important to inhibit microbial growth and improve shelf life in commercially available oral compositions such as foods, beverages, and pharmaceuticals. Therefore, naturally occurring ingredients that are effective in inhibiting microbial growth and highly safe are useful.

[0003] Quercetin is a type of flavonoid that is contained in plants such as onions either as is or as a glycoside. Non-Patent Document 1 describes that quercetin inhibits the growth of Escherichia coli and Staphylococcus aureus.

[0004] Ergothioneine is a type of sulfur-containing amino acid, and exists naturally in the L-form. L-ergothioneine is known to have useful physiological activities such as antioxidant activity. For example, Patent Document 1 describes that when ergothioneine derived from Pleurotus cornucopiae was allowed to act on immortalized human keratinocyte cells (HaCaT cells), the expression levels of human β-defensin-1 (hBD-1) and human β-defensin-3 (hBD-3) mRNA increased.

[0005] JP 2012-56914 A

[0006] Journal of Chemical and Pharmaceutical Research, 2015, 7(12):834-841

[0007] An object of the present invention is to provide a technique for effectively inhibiting the growth of microorganisms in oral compositions and the like.

[0008] As a result of intensive research aimed at solving the above problems, the present inventors have found that L-ergothioneine enhances the microbial growth inhibitory effect of quercetin or its glycoside. By using L-ergothioneine or a salt thereof in combination with quercetin or its glycoside, it is possible to effectively inhibit microbial growth.

[0009] That is, the present invention relates to the following compositions, methods for inhibiting microbial growth using oral compositions, and agents for enhancing the microbial growth inhibitory activity of quercetin or a glycoside thereof, although the present invention is not limited thereto: [1] A composition containing (A) L-ergothioneine or a salt thereof, and (B) quercetin or a glycoside thereof. [2] The composition according to [1] above, wherein the (B) quercetin or a glycoside thereof is at least one selected from the group consisting of isoquercitrin, rutin, enzymatically modified rutin, and quercitrin. [3] The composition according to [1] above, wherein the weight ratio of the content of (A) L-ergothioneine or a salt thereof (converted into L-ergothioneine) to the content of (B) quercetin or a glycoside thereof (converted into isoquercitrin) ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is 0.01 to 1.2. [4] The composition according to any one of [1] to [3] above, which is a composition for inhibiting microbial growth. [5] The composition according to [4] above, which is a composition for inhibiting microbial growth in an oral composition. [6] The composition according to [4] or [5] above, wherein the microorganism is Escherichia coli. [7] A method for inhibiting microbial growth in an oral composition, which comprises adding (A) L-ergothioneine or a salt thereof, and (B) quercetin or a glycoside thereof to the oral composition. [8] The method according to [7] above, wherein (B) quercetin or a glycoside thereof is at least one selected from the group consisting of isoquercitrin, rutin, enzymatically modified rutin, and quercitrin. [9] The method according to [7] or [8] above, wherein (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof are added to the oral composition so that the weight ratio of the content of (A) L-ergothioneine or a salt thereof (in L-ergothioneine equivalent) to the content of (B) quercetin or a glycoside thereof (in isoquercitrin equivalent) in the oral composition ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is 0.01 to 1.2.

[10] The method according to any one of [7] to [9] above, wherein the microorganism is Escherichia coli.

[11] An agent for enhancing the microbial growth inhibitory effect of quercetin or a glycoside thereof, comprising L-ergothioneine or a salt thereof.

[0010] According to the present invention, a technique for effectively inhibiting the growth of microorganisms in oral compositions and the like can be provided.

[0011] FIG. 1 is a graph showing the disinfecting effects of L-ergothioneine (test sample 1), isoquercitrin (test sample 2), and a combination of L-ergothioneine and isoquercitrin (test samples 3 and 4).

[0012] (Composition) The composition of the present invention contains (A) L-ergothioneine or a salt thereof, and (B) quercetin or a glycoside thereof. Quercetin or a glycoside thereof has an inhibitory effect on microbial growth (antibacterial effect). Combining L-ergothioneine or a salt thereof with quercetin or a glycoside thereof can enhance the inhibitory effect of quercetin or a glycoside thereof. Therefore, the combined use of L-ergothioneine or a salt thereof with quercetin or a glycoside thereof makes it possible to effectively inhibit microbial growth.

[0013] L-ergothioneine is a type of amino acid. The salt of L-ergothioneine is not particularly limited as long as it is a pharmacologically acceptable salt or a salt acceptable for use in foods and beverages, and may be either an acidic salt or a basic salt. Examples of acidic salts include inorganic acid salts such as hydrochloride, sulfate, nitrate, and phosphate; and organic acid salts such as acetate, citrate, maleate, malate, oxalate, lactate, succinate, fumarate, and propionate. Examples of basic salts include alkali metal salts such as sodium salt and potassium salt; and alkaline earth metal salts such as calcium salt and magnesium salt. As L-ergothioneine or a salt thereof, L-ergothioneine is preferably used.

[0014] L-ergothioneine or a salt thereof may be a chemically synthesized product, or may be extracted and purified from a natural product. L-ergothioneine is contained in large amounts in Golden / Yellow Oyster Mushroom (scientific name: Pleurotus cornucopiae var. citrinopileatus), a mushroom of the Pleurotus genus in the family Pleurotus. L-ergothioneine is found in mushrooms such as white button mushrooms, crimini mushrooms, and portabella mushrooms (Agaricus bisporus), Grey Oyster Mushrooms (Pleurotus ostreatus), shiitake mushrooms (Lentinula edodes), Maitake mushrooms (Grifola frondosa), reishi mushrooms (Ganoderma lucidum), Yamabushitake mushrooms (Hericium erinaceus), Yanagimatsutake mushrooms (Agrocybe aegerita), and chanterelle mushrooms (Cantharella verruca). It is also contained in mushrooms such as Pleurotus cibarius, porcini mushroom (scientific name: Boletus edulis), and morel mushroom (scientific name: Morchella esculenta). When obtaining L-ergothioneine from a natural product, it is preferable to extract it from Pleurotus lucerne. L-ergothioneine or a salt thereof can also be produced by microbial fermentation. An extract containing L-ergothioneine or a salt thereof produced by microbial fermentation, or a product purified therefrom, may also be used. Extraction and purification from natural products can be carried out by known methods. L-ergothioneine or a salt thereof may be isolated.

[0015] The content of L-ergothioneine or a salt thereof in the composition is not particularly limited, but is, for example, preferably 0.00001% by weight or more, more preferably 0.0001% by weight or more, and may be 50% by weight or less, or 10% by weight or less, preferably 0.1% by weight or less, more preferably 0.01% by weight or less, in terms of L-ergothioneine. In one embodiment, the content of L-ergothioneine or a salt thereof in the composition may be 0.00001 to 50% by weight, or 0.00001 to 10% by weight, preferably 0.00001 to 0.1% by weight, more preferably 0.0001 to 0.01% by weight. The content of L-ergothioneine or a salt thereof can be measured by high-performance liquid chromatography (HPLC). As used herein, with respect to L-ergothioneine or a salt thereof, the term "quantity converted into L-ergothioneine" or similar expressions refers to the amount of L-ergothioneine or a salt thereof as L-ergothioneine. Specifically, in the case of L-ergothioneine, it refers to the amount, and in the case of a salt of L-ergothioneine, it refers to the value obtained by multiplying the number of moles of the salt by the molecular weight of L-ergothioneine.

[0016] As used herein, "quercetin" refers to a compound belonging to the flavonol class of polyphenols. In the present invention, "quercetin glycoside" refers to a glycoside of the above-mentioned quercetin, specifically a general term for a series of compounds in which one or more sugars are glycosidically bonded to the hydroxyl group at the 3-position and / or the hydroxyl group at the 4'-position of quercetin. Quercetin glycosides may be one type of compound or two or more types of compounds. Examples of sugars (monosaccharides) bound to quercetin include glucose, rhamnose, galactose, glucuronic acid, etc., with glucose and rhamnose being preferred. The sugars bound to quercetin may be modified (e.g., malonylated).

[0017] In one embodiment, the quercetin glycoside is preferably a compound in which one or more sugars are glycosidically bonded to the hydroxyl group at the 3-position of quercetin. A quercetin glycoside in which one or more sugars are glycosidically bonded to the hydroxyl group at the 3-position of quercetin is a compound represented by the following general formula: (X)n in the following general formula represents a sugar chain. X represents a sugar (monosaccharide), and n is an integer of 1 or greater.

[0018]

[0019] The sugar constituting the sugar chain represented by X that is glycosidically bonded to quercetin is, for example, glucose, rhamnose, galactose, glucuronic acid, etc., and preferably glucose or rhamnose. Furthermore, n is not particularly limited as long as it is 1 or greater, but is preferably 1 to 16, more preferably 1 to 8. When n is 2 or greater, the X moiety may consist of one type of sugar or multiple types of sugars. In other words, when n is 2 or greater, (X)n may be a sugar chain consisting of one type of sugar or multiple types of sugars.

[0020] The quercetin glycosides of the present invention also include those obtained by transglycosylating existing quercetin glycosides by treating them with an enzyme or the like. Specific examples of quercetin glycosides of the present invention include rutin (quercetin 3-rutinoside), enzyme-treated rutin (enzyme-treated rutin), quercitrin (quercetin-3-O-rhamnoside), isoquercitrin (quercetin 3-glucoside), quercetin 3,4'-diglucoside, quercetin 4'-glucoside, quercetin 3-(6-malonylglucoside), hyperoside (quercetin 3-galactoside), and quercetin-3-O-glucuronide. Enzyme-treated rutin is a quercetin glycoside in which a sugar chain is further bound to the glucosidic moiety of isoquercitrin. Preferred examples of enzyme-treated rutin include isoquercitrin obtained by enzymatically treating rutin to remove the rhamnose sugar chain moiety and then treating the resulting isoquercitrin with a glycosyltransferase, in which a sugar chain consisting of 1 to 7 glucose units is bonded to isoquercitrin, and mixtures thereof as the main component. In one aspect, quercetin or a glycoside thereof is preferably a quercetin glycoside, more preferably a quercetin glycoside in which one or more sugars are glycosidically bonded to the hydroxyl group at the 3-position of quercetin, even more preferably at least one selected from the group consisting of isoquercitrin, rutin, enzyme-treated rutin, and quercitrin, and even more preferably isoquercitrin or enzyme-treated rutin. As the quercetin glycoside, a compound in which 1 to 8 glucose units are glycosidically bonded to the hydroxyl group at the 3-position of quercetin (e.g., isoquercitrin, a glycoside in which 1 to 7 glucose units are bonded to isoquercitrin) is particularly preferred, and isoquercitrin is most preferred.

[0021] In the present invention, there are no particular limitations on the origin or production method for obtaining quercetin or its glycoside. For example, plants known to contain large amounts of quercetin or its glycoside include buckwheat, sophora japonica, capers, apples, tea, onions, grapes, broccoli, mulukhiyah, raspberries, cowberries, cranberries, opuntia, leafy vegetables, and citrus fruits, and quercetin or its glycoside can be obtained from these plants. The quercetin or its glycoside used in the present invention can be a concentrate or purified extract derived from a natural product such as the above-mentioned plants, which has been enriched in quercetin or its glycoside through concentration, purification, or other procedures, as long as the effects of the present invention are achieved. For example, a concentrate or purified extract containing quercetin or its glycoside can be used. Known methods can be used for concentration or purification. Purified or isolated quercetin or its glycoside may also be used in the present invention. Chemically synthesized quercetin or its glycoside can also be used.

[0022] The content of quercetin or its glycoside in the composition is, for example, preferably 0.0001 wt % or more, more preferably 0.001 wt % or more, and may be 50 wt % or less, 10 wt % or less, preferably 1 wt % or less, and more preferably 0.1 wt % or less, calculated as isoquercitrin. In one embodiment, the content of quercetin or its glycoside in the composition may be 0.0001 to 50 wt %, or 0.0001 to 10 wt %, preferably 0.0001 to 1 wt %, and more preferably 0.001 to 0.1 wt %. The content of quercetin or its glycoside can be measured by high-performance liquid chromatography (HPLC). In this specification, the term "quantity in isoquercitrin equivalent" or similar expressions for quercetin or its glycoside refers to the amount of quercetin or its glycoside as isoquercitrin. Specifically, when the compound is isoquercitrin, it means the amount thereof, and when the compound is quercetin or a quercetin glycoside other than isoquercitrin, it means the value obtained by multiplying the number of moles of the compound by the molecular weight of isoquercitrin.

[0023] In the present invention, the weight ratio of the content of (A) L-ergothioneine or a salt thereof (in L-ergothioneine equivalent) to the content of (B) quercetin or a glycoside thereof (in isoquercitrin equivalent) ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.025 or more, and is preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1 or less. When the weight ratio of the content of (A) L-ergothioneine or a salt thereof (in L-ergothioneine equivalent) to the content of (B) quercetin or a glycoside thereof ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is within the above range, the microbial growth inhibitory effect of quercetin or a glycoside thereof is effectively enhanced. In one embodiment, the weight ratio ((A) in terms of L-ergothioneine / (B) in terms of isoquercitrin) is preferably 0.01 to 1.2, more preferably 0.02 to 1.2, even more preferably 0.025 to 1.2, still more preferably 0.025 to 1.1, and particularly preferably 0.025 to 1. The composition of the present invention preferably contains (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof in the above weight ratio.

[0024] The composition of the present invention inhibits microbial growth by containing (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof. The composition of the present invention is useful as a composition (preferably an oral composition) in which microbial growth is inhibited.

[0025] In academic terms, microorganisms include not only bacteria but also fungi (mushrooms, molds, yeasts, etc.), viruses, microalgae, etc., but in this specification, microorganisms refer to bacteria. In the present invention, Escherichia coli is preferred as the microorganism. By combining L-ergothioneine or a salt thereof with quercetin or a glycoside thereof, an excellent growth inhibitory effect against Escherichia coli can be exerted.

[0026] The composition of the present invention can be in the form of, for example, a food or drink, a pharmaceutical product, a quasi-drug, a feed, etc. The composition of the present invention may itself be a food or drink, a pharmaceutical product, a quasi-drug, a feed, etc., or may be a material or preparation to be incorporated into these. In one aspect, when the composition of the present invention is used as a food or drink, a pharmaceutical product, a quasi-drug, a feed, etc., the content of L-ergothioneine or a salt thereof in the composition is preferably 0.0001 to 0.1 wt %, more preferably 0.001 to 0.01 wt %, calculated as L-ergothioneine. The content of quercetin or a glycoside thereof in the composition is preferably 0.001 to 1 wt %, more preferably 0.01 to 0.1 wt %, calculated as isoquercitrin.

[0027] In one aspect, the composition of the present invention is preferably an oral composition. Examples of oral compositions include foods and beverages, oral medicines, quasi-drugs, feed, etc., preferably foods and beverages or oral medicines, more preferably foods and beverages. In one aspect, the composition of the present invention is useful as an oral composition in which microbial growth is inhibited, preferably an oral composition in which Escherichia coli growth is inhibited. In one aspect, the composition of the present invention is useful, for example, as a foods and beverages, oral medicines, oral quasi-drugs, feed, etc. in which microbial growth is inhibited.

[0028] The composition of the present invention may contain optional additives and optional components in addition to L-ergothioneine or a salt thereof and quercetin or a glycoside thereof, as long as the effects of the present invention are not impaired. These additives and components can be selected depending on the form of the composition, and those that are generally usable for foods and beverages, pharmaceuticals, quasi-drugs, feed, etc. can be used. When the composition of the present invention is made into a food or beverage, pharmaceutical, quasi-drug, feed, etc., there are no particular limitations on the method for producing the composition, and it can be produced by a general method. The form of the composition of the present invention is not particularly limited, and it may be in a solid form (powder, granules, tablet, etc.), liquid form, paste, etc.

[0029] For example, when the composition of the present invention is made into a food or beverage, various foods and beverages can be prepared by blending L-ergothioneine or a salt thereof and quercetin or a glycoside thereof with ingredients that can be used in foods and beverages (e.g., food ingredients, food additives used as needed, etc.). The foods and beverages are not particularly limited, and examples include general foods and beverages, health foods, health drinks, foods with functional claims, foods for specified health uses, health supplements, foods and beverages for patients, etc. The health foods, foods with functional claims, foods for specified health uses, health supplements, etc. can be made into various dosage forms, such as fine granules, tablets, granules, powders, capsules, chewable tablets, syrups, liquids, and liquid diets.

[0030] When the composition of the present invention is used as a pharmaceutical or quasi-drug, for example, L-ergothioneine or a salt thereof and quercetin or a glycoside thereof may be combined with a pharmacologically acceptable carrier and, if necessary, additives to produce a pharmaceutical or quasi-drug in various dosage forms. Such carriers, additives, etc. may be any pharmacologically acceptable carriers that can be used in pharmaceuticals or quasi-drugs, and may include, for example, one or more of excipients, binders, disintegrants, lubricants, antioxidants, colorants, etc. The pharmaceutical or quasi-drug may be administered orally or parenterally, with oral administration being preferred. When the composition of the present invention is used as a pharmaceutical or quasi-drug, it is preferably an oral pharmaceutical or quasi-drug. Dosage forms for oral administration include liquids, tablets, powders, fine granules, granules, sugar-coated tablets, capsules, suspensions, emulsions, chewable tablets, etc. Dosage forms for parenteral administration include injections and infusions.

[0031] When the composition of the present invention is used as feed, L-ergothioneine or a salt thereof and quercetin or a glycoside thereof may be blended into the feed. Feed also includes feed additives. Examples of feed include livestock feed for cows, pigs, chickens, sheep, horses, etc.; small animal feed for rabbits, rats, mice, etc.; and pet food for dogs, cats, small birds, etc.

[0032] When the composition of the present invention is an oral composition, the subject to which the composition of the present invention is ingested or administered (also referred to as the administration subject) is not particularly limited, and is preferably a human or a non-human mammal, more preferably a human.

[0033] When the composition of the present invention is used as an oral composition, the intake amount (administration amount) of the composition of the present invention is not particularly limited, but for example, for a human (adult), the intake amount in terms of L-ergothioneine is preferably 2 to 50 mg, more preferably 5 to 25 mg, even more preferably 5 to 20 mg, and particularly preferably 10 to 20 mg per day.

[0034] A combination of (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof can be used as an active ingredient for inhibiting microbial growth. In one aspect, the composition of the present invention can be suitably used, for example, to inhibit microbial growth. In one aspect, the composition of the present invention may be a composition for inhibiting microbial growth. L-ergothioneine or a salt thereof, and quercetin or a glycoside thereof are compounds contained in natural products and foods and beverages, and are ingested as such. The composition of the present invention can be suitably used, for example, to inhibit microbial growth in an oral composition. In one aspect, the composition of the present invention can be suitably used as a composition for inhibiting microbial growth in an oral composition. A composition for inhibiting microbial growth can also be referred to as a microbial growth inhibitor. In one aspect, the composition of the present invention can be suitably used as a composition for inhibiting Escherichia coli growth.

[0035] In one aspect, the composition of the present invention can be used by adding it to, for example, an oral composition. When the composition of the present invention is used to inhibit the growth of microorganisms in an oral composition, the composition of the present invention can be added to the oral composition. In one aspect, the composition of the present invention can be used as a food additive. The oral composition to which the composition of the present invention is added is not particularly limited, and examples include foods and beverages, oral pharmaceuticals, oral quasi-drugs, feeds, etc., and preferably foods and beverages. In one aspect, when the composition of the present invention is used by adding it to foods and beverages, etc. as a composition for inhibiting microbial growth, the total content of (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof in the composition may be, for example, 0.01 to 99 wt %, and preferably 0.1 to 90 wt %.

[0036] When the composition of the present invention is added to an oral composition for the purpose of achieving a microbial growth inhibitory effect, the amount added is preferably such that the content of L-ergothioneine or a salt thereof in the oral composition is 0.00001 to 0.1 wt %, more preferably 0.0001 to 0.01 wt %, calculated as L-ergothioneine. Furthermore, the amount of quercetin or a glycoside thereof is preferably such that the content of quercetin or a glycoside thereof in the oral composition is 0.001 to 1 wt %, more preferably 0.01 to 0.1 wt %, calculated as isoquercitrin. From the viewpoint of achieving a microbial growth inhibitory effect, it is preferred to add the composition in such amounts that the contents of L-ergothioneine or a salt thereof and quercetin or a glycoside thereof are as described above.

[0037] (Method for Inhibiting Microbial Growth) The present invention also encompasses a method for inhibiting microbial growth in an oral composition, which comprises adding (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof to the oral composition. In the method of the present invention, preferred embodiments of (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof are the same as those of the composition of the present invention described above. For example, the quercetin or glycoside thereof is preferably at least one selected from the group consisting of isoquercitrin, rutin, enzymatically modified rutin, and quercitrin.

[0038] In the method of the present invention, the microorganism and its preferred embodiments are the same as those described above, and preferably Escherichia coli. The method of the present invention is preferably a method for inhibiting the growth of Escherichia coli using an oral composition. The oral composition is not particularly limited, and examples thereof include the above-mentioned foods and beverages, oral pharmaceuticals, oral quasi-drugs, feeds, etc.

[0039] In the method of the present invention, it is preferable to add (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof to the oral composition so that the weight ratio of the content of (A) L-ergothioneine or a salt thereof (in L-ergothioneine equivalent) to the content of (B) quercetin or a glycoside thereof (in isoquercitrin equivalent) in the oral composition ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is 0.01 or more. This weight ratio ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is more preferably 0.02 or more, even more preferably 0.025 or more, and preferably 1.2 or less, more preferably 1.1 or less, and even more preferably 1 or less. When the weight ratio of (A) L-ergothioneine or a salt thereof (converted to L-ergothioneine) to (B) quercetin or a glycoside thereof (converted to isoquercitrin) ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is within the above range, the microbial growth inhibitory effect of quercetin or a glycoside thereof is effectively enhanced. In one embodiment, the weight ratio ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) is preferably 0.01 to 1.2, more preferably 0.02 to 1.2, even more preferably 0.025 to 1.2, even more preferably 0.025 to 1.1, and particularly preferably 0.025 to 1. It is preferable to add (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof to the oral composition so that the weight ratio of the content of (A) L-ergothioneine or a salt thereof (in L-ergothioneine equivalent) to the content of (B) quercetin or a glycoside thereof (in isoquercitrin equivalent) in the oral composition ((A) in L-ergothioneine equivalent / (B) in isoquercitrin equivalent) falls within the above range.

[0040] The amount of L-ergothioneine or a salt thereof added is preferably an amount that results in a content of L-ergothioneine or a salt thereof in the oral composition of 0.00001 to 0.1% by weight, more preferably 0.0001 to 0.01% by weight, calculated as L-ergothioneine.The amount of quercetin or a glycoside thereof added is preferably an amount that results in a content of quercetin or a glycoside thereof in the oral composition of 0.001 to 1% by weight, more preferably 0.01 to 0.1% by weight, calculated as isoquercitrin.

[0041] In the method of the present invention, (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof may be added separately to the oral composition, or a composition containing them may be added to the oral composition. For example, (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof may be added to the oral composition using the composition of the present invention described above.

[0042] (An agent for enhancing the microbial growth inhibitory effect of quercetin or a glycoside thereof) The present invention also encompasses an agent for enhancing the microbial growth inhibitory effect of quercetin or a glycoside thereof, comprising L-ergothioneine or a salt thereof. L-ergothioneine or a salt thereof can be used as an active ingredient for enhancing the microbial growth inhibitory effect of quercetin or a glycoside thereof. L-ergothioneine or a salt thereof can be suitably used, for example, to enhance the Escherichia coli growth inhibitory effect of quercetin or a glycoside thereof.

[0043] The present invention also encompasses the use of (A) L-ergothioneine or a salt thereof and (B) quercetin or a glycoside thereof for producing a composition for inhibiting microbial growth. The present invention also encompasses the use of L-ergothioneine or a salt thereof for enhancing the microbial growth inhibitory activity of quercetin or a glycoside thereof.

[0044] In this specification, a numerical range expressed by a lower limit and an upper limit, i.e., "lower limit to upper limit," includes the lower limit and the upper limit. For example, a range expressed by "1 to 2" means 1 or more and 2 or less, including 1 and 2. In this specification, the upper limit and the lower limit may be any combination of ranges.

[0045] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0046] Example 1 The disinfecting (microbial growth inhibitory) effects of L-ergothioneine (hereinafter sometimes simply referred to as ergothioneine) and quercetin glycoside were investigated. Isoquercitrin (quercetin 3-glucoside, manufactured by Cayman Chemical Co.) was used as the quercetin glycoside. Escherichia coli (NBRC 3972) was used as the test bacterium.

[0047] (Preparation of test bacterial solution) Escherichia coli was inoculated onto a normal agar medium and cultured at 30 to 35°C for 24 hours. After the culture, the number of bacteria was reduced to 10 using physiological saline. ８ The test bacterial solution was prepared so as to have a concentration of CFU / mL.

[0048] (Preparation of Test Samples) Phosphate buffered saline and ergothioneine were mixed to prepare test sample 1 (ergothioneine concentration 100 ppm (0.01 wt%)). Phosphate buffered saline and isoquercitrin were mixed to prepare test sample 2 (isoquercitrin concentration 100 ppm (0.01 wt%)). Phosphate buffered saline, ergothioneine, and isoquercitrin were mixed to prepare test sample 3 (ergothioneine concentration 2.5 ppm (0.00025 wt%), isoquercitrin concentration 100 ppm (0.01 wt%)). Phosphate buffered saline, ergothioneine, and isoquercitrin were mixed to prepare test sample 4 (ergothioneine concentration 100 ppm (0.01 wt%), isoquercitrin concentration 100 ppm (0.01 wt%)). Phosphate buffered saline was used as a control. Table 1 shows the concentrations of (A) ergothioneine and (B) isoquercitrin in the test samples, and the weight ratio of (A) ergothioneine to (B) isoquercitrin ((A) / (B)).

[0049]

[0050] (Inoculation and cultivation of test bacterial solution) 0.05 mL of the test bacterial solution was inoculated into 5 mL of the test sample, and the mixture was allowed to stand at room temperature.

[0051] (Measurement of Viable Bacteria Count) One hour after inoculation, a 10-fold dilution of the test sample inoculated with the test bacterial solution was prepared in soybean casein digest liquid medium supplemented with lecithin and polysorbate 80. The resulting dilution containing E. coli was inoculated onto soybean casein digest agar medium supplemented with lecithin and polysorbate 80 and cultured at 30 to 35°C for 3 to 5 days. After culture, the formed colonies were counted and the viable bacterial count was calculated (n = 3). The sterilization effect (%) was calculated from the viable bacterial count (average value of n = 3) using the following formula: sterilization effect (%) = 100 - 100 × (viable bacterial count in test sample) / (viable bacterial count in control) The results are shown in Figure 1.

[0052] FIG. 1 is a graph showing the disinfection effects of L-ergothioneine (Test Sample 1), isoquercitrin (Test Sample 2), and a combination of L-ergothioneine and isoquercitrin (Test Samples 3 and 4). L-ergothioneine alone was not found to have any disinfecting effect on Escherichia coli. Although isoquercitrin inhibited the growth of Escherichia coli when used alone, the inhibitory effect on Escherichia coli growth obtained by the combination of L-ergothioneine and isoquercitrin was a synergistic effect significantly superior to the additive effect predicted from the effects obtained by using each component alone. It was found that the combined use of L-ergothioneine and isoquercitrin provided an excellent disinfecting effect against microorganisms, i.e., an excellent inhibitory effect on microbial growth.

Claims

DEPCT6821 / 10 / 25671. Composition consisting of:(A)L-ergothionine or its salt; and(B)Quercitin or its glycoside.2.Method according to claim 1, where(B)Quercitin or its glycoside is at least one type selected from a group consisting of isoquercitrin, rutin, enzymatically treated rutin, and quercitin.3.Method according to claim 1 or 2, where the weight ratio of (A)L-ergothionine or its salt in terms of L-ergothionine. (B) Quercetin or glycoside of the substance in terms of isoquercitrin, i.e. (A) in terms of L-ergothionine / (B) in terms of isoquercitrin, with values ​​of 0.01 to 1.

24. Method according to claim 1 or 2, where the substance is an inhibitory element for microbial growth.

5. Method according to claim 4, where the substance is an inhibitory element for microbial growth in an oral formulation.

6. Method according to claim 4, where the microorganism is Escherichia coli.7.Methods of inhibiting microbial growth in oral formulations, which include: addition of (A) L-ergothionine or its salt and (B) quercetin or its glycoside to the oral formulation.

8. Method according to claim 7, where (B) quercetin or its glycoside is at least one type selected from a group consisting of isoquercitrin, rutin, enzymatically treated rutin, and quercetin.

9. Method according to claim 7 or 8, where (A) L -L-Ergothioneine or its salt and (B)Quercetin or its glycoside are added to the oral formulation in such a way that the weight ratio of (A)L-Ergothioneine or its salt in terms of L-Ergothioneine to (B)Quercetin or its glycoside in terms of isoquercitrin, i.e. (A) in terms of L-Ergothioneine / (B) in terms of isoquercitrin, in the oral formulation is 0.01 to 1.

210. Method according to claim 7 or 8, where the microorganism is Escherichiacoli11.A substance that enhances the antimicrobial activity of quercetin or its glycoside, containing: L-ergothionine or its salt;

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