JP6098929B2 - Antidepressant or anxiolytic - Google Patents

Description

  The present invention relates to a peptide having an antidepressant or anxiolytic action, and an antidepressant or anxiolytic agent containing the peptide as an active ingredient.

  In modern society, stress has become normal, and there are many cases of mental illness caused by stress. In particular, depression and anxiety have become a social problem with an increasing number of patients.

  Depression is a mental disorder characterized by symptoms such as feeling depressed, not recovering for more than a few days or weeks, feelings of loneliness, loneliness, despair, strong complex, and chronic feeling of self-responsibility. Furthermore, if physical symptoms such as fatigue, loss of appetite, and palpitation also appear, it will become more difficult to return to society. As a treatment (or antidepressant) for depression, monoamine uptake inhibitors such as tricyclic antidepressants such as imipramine, clomipramine and trimipramine, tetracyclic antidepressants such as maprotiline and mianserin, and tria such as trazodone Known are zolopyridine antidepressants, benzketoxime selective serotonin reuptake inhibitors such as fluvoxamine, and the like. However, these antidepressants are said to be ineffective in 30-50% of patients who are administered. More recently, drugs with new mechanisms of action such as angiogenesis inhibitors, glucocorticoid inhibitors, inflammatory cytokine inhibitors, neurokinin inhibitors, GABA agonists / inhibitors have been proposed, all of which are in the research stage Therefore, it has not been used clinically (Non-patent Document 1).

  Anxiety is a type of mental illness that does not have a clear subject or has a fear of fear that does not match the subject. When anxiety is felt, physical symptoms such as palpitations, cold sweat, tremors, and stiffness occur, and chronicity causes mental disorders, mood disorders, personality disorders, behavioral disorders, and sleep disorders. As anti-anxiety drugs, pharmaceuticals such as benzodiazepines, thienodiazepines, diphenylmethanes, carbamates, etc. are known, and their mechanism of action is γ-, such as limbic, hypothalamus, mesencephalic reticulum, etc. A system via an aminobutyric acid (GABA) receptor is known (Non-patent Document 2). Antidepressants and anxiolytics, which may be prescribed together depending on the symptoms, are drugs belonging to different classes with different mechanisms of action and efficacy as described above.

  Antidepressants and anxiolytics need to be taken over a long period of time to improve symptoms, which can cause drowsiness, dizziness, weakness, distraction, constipation, loss of appetite, liver dysfunction, etc. It is known that there may be side effects and the risk of developing drug addiction with continuous use. Therefore, development of a preventive or therapeutic agent for depression or anxiety that can be safely taken for a long time is required. For example, Patent Document 1 discloses that peptides derived from milk-derived αS1 casein are effective for anxiety. Patent Document 2 discloses that Tyr-Pro, a peptide, regulates autonomic nerve activity and exhibits anxiolytic action.

  Pyroglutamyl peptide is known to have an effect of improving liver disease (Patent Document 3) and an anti-inflammatory effect (Patent Document 4). The peptide is expected as an active ingredient of a preparation that can be taken for a long period of time because it has no worry about side effects, is easy to ingest, and is inexpensive.

Special table 2011-524163 gazette International Publication No. 2010/110439 Pamphlet International Publication No. 2008/117730 Pamphlet International Publication No. 2010/032322 Pamphlet

Proceedings of the 129th Japan Medical Society Symposium Depression, pp. 24-31 Clinical pharmacology Chapter III Pharmacotherapy clinical pharmacology of psychotropic drugs, Japanese Society of Clinical Pharmacology (edition), Medical School (published), 1996

  The present invention relates to providing an antidepressant or anxiolytic agent that can be safely taken for a long period of time.

  As a result of earnest search for components having antidepressant or anxiolytic action, the present inventors have found that certain pyroglutamyl peptides, which have not been known so far, have such action. It was. Furthermore, the present inventors have found that the pyroglutamyl peptide has an excellent effect of having both an antidepressant action and an anxiolytic action.

That is, the present invention provides the following formula:
pyroGlu- (X) n-A
(Wherein X is Gln or Asn, A is Gln, Asn, Leu, Ile or Val, and n is an integer of 0 or 1)
An antidepressant or anxiolytic agent comprising at least one selected from the group consisting of a peptide consisting of the amino acid sequence represented by the formula:

  According to the present invention, it is possible to prevent depression or anxiety that is highly effective, has no side effects, is easy to ingest, is inexpensive, and can be taken for a long time in terms of cost and safety. A therapeutic agent can be provided.

  The antidepressant or anxiolytic agent of the present invention is a peptide comprising the amino acid sequence represented by the formula: pyroGlu- (X) n-A (hereinafter, the peptide may be referred to as the peptide of the present invention) or its It contains at least one selected from the group consisting of salts as an active ingredient. In the above formula, pyroGlu is pyroglutamic acid, which is a ring of the amide group at the γ position and the amino group at the α position of the glutamic acid residue; X is Gln (glutamine) or Asn (asparagine); A is Gln, Asn, Leu (leucine), Ile (isoleucine) or Val (valine), preferably Leu, Ile or Val, more preferably Leu; n is 0 or 1, preferably 0 . Examples of the peptide of the present invention represented by the above formula include pyroGlu-Leu, pyroGlu-Gln-Leu, pyroGlu-Asn-Leu, pyroGlu-Gln, pyroGlu-Asn, pyroGlu-Ile, and pyroGlu-Val. .

  The salt of the peptide of the present invention is not particularly limited as long as it is a pharmaceutically or food acceptable salt, and examples thereof include acid addition salts and base addition salts. Examples of the acid addition salt include salts with inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and salts with organic acids such as acetic acid, malic acid, succinic acid, tartaric acid, and citric acid. Base addition salts include salts with alkali metals such as sodium and potassium, salts with alkaline earth metals such as calcium and magnesium, and salts with amines such as ammonium and triethylamine.

  The antidepressant or anxiolytic agent of the present invention may contain at least one selected from the group consisting of the peptide of the present invention or a salt thereof as an active ingredient. That is, the active ingredient of the present invention may be any one of the peptides of the present invention listed above or any one of the salts of the peptides of the present invention listed above, or two or more of the present invention. Any combination of peptides or any combination of two or more salts of the peptides of the invention, or one or more peptides of the invention and one or more of the peptides of the invention. Any combination with a peptide salt may be used.

  The peptide of the present invention may be a partial hydrolyzate of a natural or recombinant protein, a peptide prepared by a chemical synthesis method or a genetic engineering method, or a combination thereof.

  When the peptide of the present invention is prepared by partial hydrolysis of a natural protein, a known method can be appropriately employed as a protein hydrolysis method. Specific examples include a method of hydrolyzing with an acid and a method of hydrolyzing with a protease.

  The natural protein used for hydrolysis may be any protein as long as it is available, but it is preferable to use a protein that has been confirmed to be safe for living organisms. Examples of such proteins include animal proteins derived from animal meat, skin, milk, blood and the like, and vegetable proteins derived from grains such as rice and wheat, fruits such as straw and peaches, and the like. . Among these, proteins such as gluten contained in wheat seeds are known to be rich in glutamine, and are preferable as a raw material for preparing the peptide of the present invention.

  A conventional method can be adopted as a method for hydrolyzing a protein using an acid. Examples of the acid include mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and sulfurous acid, and organic acids such as oxalic acid, citric acid, acetic acid, and formic acid.

  When hydrolyzing with an acid, the concentration of the protein in the aqueous medium needs to be appropriately adjusted depending on the type and normality of the acid, but it is usually preferable to adjust to 1.0 to 80% by mass.

  When a protein is hydrolyzed using a protease, a hydrolyzate can be produced by acting one or more kinds of proteases in an aqueous medium. A method using an acidic protease alone and a method using an acidic protease and a neutral protease or an alkaline protease are preferred in that they can be efficiently hydrolyzed. Moreover, when using vegetable protein as protein, the starch and fiber which are contained in a plant may become an obstacle at the time of protease action or refinement | purification. In such a case, it is preferable to cause a glycolytic enzyme such as amylase or cellulase to act before or after the aforementioned protease is allowed to act, or together with the protease.

  As a method for purifying the protein hydrolyzate thus obtained, a method for filtering insoluble matter, a method for fractionation (extraction) with hydrous alcohol, gel filtration chromatography, high performance liquid chromatography (HPLC), Examples include a method of purification by autofocusing.

  When the peptide of the present invention is prepared by a genetic engineering method, cells genetically modified to produce the peptide of the present invention are cultured, and then the target peptide produced is recovered from the culture. . Although it does not specifically limit as a cell, Various animal cells, bacteria cells, such as yeast and colon_bacillus | E._coli, etc. are mentioned.

  As a general technique, a recombinant cell capable of producing the peptide can be prepared by introducing a vector containing a gene encoding the target peptide of the present invention into the cell. Examples of vectors include plasmid vectors and virus vectors. Examples of methods for introducing a plasmid into cells include conventional methods such as a lipofection method, an electroporation method, and a particle gun method. Vector construction and cell introduction procedures are well known to those skilled in the art, and vector construction and gene introduction kits are commercially available. A cell into which the gene has been introduced is cultured, and a recombinant cell producing the desired peptide of the present invention is selected. The peptide of the present invention can be obtained by culturing the selected recombinant cells and recovering the target peptide of the present invention produced in the culture. Examples of the method for recovering the peptide from the culture include known methods such as high performance liquid chromatography (HPLC).

  Alternatively, the target peptide of the present invention may be prepared by causing a recombinant cell to produce a recombinant protein containing the peptide of the present invention and further partially hydrolyzing it with the procedure described above.

  When the peptide of the present invention is prepared by a chemical synthesis method, either a liquid phase synthesis method or a solid phase synthesis method may be used. Preferably, a solid-phase synthesis method in which the C-terminal of an amino acid or peptide is immobilized on a solid-phase carrier via a linker and the amino acids are sequentially extended to the N-terminal side is preferable. When the solid-phase synthesis method is employed, the peptide synthesizer (for example, PSSM8 manufactured by Shimadzu, Model 433A manufactured by ABI, etc.) can also be used for synthesis.

  Any solid phase carrier used in the solid phase synthesis may be used as long as it has a binding property to the carboxyl group of Gln, Asn, Leu, Ile, or Val, which is the C-terminal amino acid of the peptide of the present invention. For example, benzhydrylamine resin (BHA resin), chloromethyl resin, oxymethyl resin, aminomethyl resin, methylbenzhydryl resin (MBHA resin), acetamide methyl resin (PAM resin), p-alkoxybenzyl alcohol resin (Wang resin), 4-aminomethylphenoxymethyl resin, 4-hydroxymethylphenoxymethyl resin, and the like.

  As an example of a specific synthesis method, a procedure for preparing pyroGlu-Gln-Gln, which is a peptide of the present invention, is shown below.

  A product in which the carboxyl group of glutamine (Gln) which is the C-terminal amino acid of the target peptide is protected is prepared, and then the amino group is added to a Boc (tert-butyloxycarbonyl) group or Fmoc (9-fluorenylmethoxycarbonyl). ) Glutamine (Gln), which is the second amino acid protected by a protecting group such as a group and having a carboxyl group activated, is condensed. Next, after removing the protecting group of the amino group of the N-terminal glutamine of the produced Gln-Gln dipeptide, the amino group is a Boc (tert-butyloxycarbonyl) group or an Fmoc (9-fluorenylmethoxycarbonyl) group or the like. Glutamine (Gln), which is the third amino acid protected by the protecting group and activated by the carboxyl group, is condensed. When using the solid phase synthesis method, instead of protecting the carboxyl group of the glutamine of the C-terminal amino acid, it may be bound to a solid phase carrier.

  Activation of the carboxyl group involves reacting the carboxyl group with various reagents to form a corresponding acid chloride, acid anhydride or mixed acid anhydride, azide, or an active ester such as -ONp or -OBt. Can be performed. The peptide condensation reaction may be carried out by using a condensing agent or a racemization inhibitor such as dicyclohexylcarbodiimide (DCC), water-soluble carbodiimide (WSCD), carbodiimide reagents such as carbodiimidazole, tetraethylpyrophosphate, 1-hydroxybenzotriazole ( HOBt) can also be performed.

  After completion of the synthesis reaction, in the case of the solid phase synthesis method, the peptide is dissociated from the solid phase carrier, all protecting groups are removed, and then washed to obtain a Gln-Gln-Gln tripeptide in a crude peptide state. be able to. Next, the peptide of the present invention can be obtained by cyclizing N-terminal glutamine to pyroglutamic acid. Cyclization proceeds gradually even in aqueous solution, but can be accelerated by increasing the temperature. When using the liquid phase synthesis method, the C-terminal amino acid is not bound to the solid phase carrier and can be synthesized by the same means as in the solid phase synthesis method.

  Alternatively, the amino acid or peptide having a C-terminal carboxyl group protected by the above procedure and pyroglutamic acid in which the N-terminal amino group is protected by a protective group such as a Boc group or an Fmoc group and the carboxyl group is activated. The peptide of the present invention can be prepared by subjecting it to a condensation reaction.

  The crude peptide containing the peptide of the present invention obtained by the above procedure can be appropriately purified by a known method such as high performance liquid chromatography (HPLC) to obtain a highly pure peptide.

  As the amino acid constituting the peptide of the present invention, any of D-form, L-form, and DL-form (racemic form) can be used, but the L-form is preferably used. When the peptide of the present invention is prepared using a partial hydrolysis method of a natural protein or a recombinant cell, all of the constituent amino acids are usually in the L form.

  When the peptide of the present invention is prepared by a chemical synthesis method, even if the constituent amino acids are all peptides consisting of L-amino acids or D-amino acids, some of the amino acids are L-amino acids and the rest are D-amino acids. The peptides of the present invention are all included in the peptides of the present invention. In the peptide chemical synthesis method, the peptide of the present invention having the target amino acid sequence can be synthesized by sequentially condensing and extending amino acids from the C-terminal side to the N-terminal side. At this time, by using the L-form or D-form of each amino acid, all of the constituent amino acids are peptides composed of L-amino acids or D-amino acids, or any amino acid is an L-amino acid and the rest is from D-amino acids Can be synthesized.

  The composition of the peptide of the present invention can be confirmed by amino acid analysis. At that time, in the acid hydrolysis method that is used as a general amino acid analysis method, both pyroglutamic acid and glutamine are detected as glutamic acid. Therefore, for the analysis of glutamine and pyroglutamic acid, a specific enzyme is used for each. A method of using and quantifying after decomposition is preferably used. When the peptide is a synthetic product, the composition can be determined from the amount and ratio of each amino acid used at the time of synthesis.

  The peptides or salts thereof of the present invention thus obtained are, as shown in the examples described later, a forced swimming test that is widely used as an evaluation system for depressive symptoms, and an elevated structure that is generally used as an evaluation system for anxiety symptoms. In any of the formula ten o'clock maze tests, it showed a marked symptom improving action. That is, the peptide of the present invention or a salt thereof has an action of improving both depressive symptoms and anxiety symptoms.

  Therefore, the peptide of the present invention or a salt thereof can be used as any active ingredient of an antidepressant and an anxiolytic agent. In one embodiment, the peptide of the present invention or a salt thereof is used as an active ingredient of an antidepressant for the prevention or treatment of depression symptoms such as tragedy, loneliness, despair, strong complex, self-responsibility. Furthermore, it can be used for the prevention or treatment of physical symptoms associated with depression, such as fatigue and loss of appetite. In particular, the peptide of the present invention or a salt thereof is useful for the prevention or treatment of symptoms where conventional anti-inflammatory agents are not effective. In another embodiment, the peptide of the present invention or a salt thereof can be used as an active ingredient of an anxiolytic agent for the prevention or treatment of fear that is an anxiety symptom. It can be used for the prevention or treatment of palpitations, cold sweats, tremors, stiffness, etc., or the prevention or treatment of mental disorders, mood disorders, personality disorders, behavioral disorders, sleep disorders, etc. caused by chronic anxiety. In a further embodiment, the peptide of the present invention or a salt thereof is provided as an antidepressant and anxiolytic agent, and is used for the prevention or treatment of the above-mentioned depression and anxiety symptoms. In a further embodiment, since the peptide of the present invention or a salt thereof alone has an antidepressant action and an anxiolytic action, the disease in which an antidepressant or an anxiolytic drug is prescribed, such as schizophrenia, sleep disorder (insomnia) Symptom, sleep deprivation, etc.), panic disorder, physical symptoms associated with stress (for example, muscle tone, stiff shoulders, back pain or headache, gastrointestinal symptoms, autonomic dysfunction etc.).

  As used herein, prevention of symptoms includes suppressing and delaying the onset of symptoms and includes not only prevention of the first onset of symptoms but also prevention of recurrence of symptoms after treatment. As used herein, treatment of symptoms includes healing of symptoms, amelioration of symptoms, and suppression of progression of symptoms.

  The peptide of the present invention or a salt thereof can be used to produce a composition, medicament, food or drink, feed, etc. for preventing or treating the above-mentioned depressive symptoms and / or anxiety symptoms. Therefore, according to the present invention, there are provided compositions, medicaments, foods and drinks, feeds and the like for the prevention or treatment of depressive symptoms and / or anxiety symptoms containing the peptides of the present invention or salts thereof. The composition, medicine, food and drink, and feed can be applied to a human or non-human mammal having, suspected of, or at risk of having the above-mentioned depressive symptoms and / or anxiety symptoms. Non-human mammals include pets such as dogs and cats, livestock animals such as horses, cows and pigs, and animals kept in breeding facilities.

  In addition to the peptide of the present invention, which is an active ingredient, or a salt thereof, the composition, medicine, food and drink, and feed provided by the present invention include various additives that are usually used in the production of medicine, food, and feed. In addition, various active substances may coexist. Examples of such additives and active substances include various fats and oils, crude drugs, amino acids, polyhydric alcohols, natural polymers, vitamins, minerals, dietary fibers, surfactants, purified water, excipients, stabilizers, and pH adjusters. , Antioxidants, sweeteners, flavoring ingredients, acidulants, colorants, and flavors. In addition, the peptide of the present invention or a salt thereof can be administered or taken in combination or in combination with one or more other active ingredients having antidepressant or anxiolytic activity. Therefore, the antidepressant or anxiolytic agent of the present invention may contain other active ingredients having an antidepressant or anxiolytic action in addition to the peptide of the present invention or a salt thereof.

  Examples of the various fats and oils include vegetable fats and oils such as soybean oil, safflower oil and olive oil, and animal fats and oils such as beef tallow and sardine oil.

  Examples of the herbal medicine include cow yellow, ground yellow, eggplant, royal jelly, carrot and deer.

  Examples of the amino acid include cysteine, leucine, arginine and the like.

  Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, glycerin, and sugar alcohol. Examples of the sugar alcohol include sorbitol, erythritol, xylitol, maltitol, mannitol and the like.

  Examples of the natural polymer include gum arabic, agar, water-soluble corn fiber, gelatin, xanthan gum, casein, gluten or gluten hydrolyzate, lecithin, and dextrin.

  Examples of the various vitamins include vitamin C (ascorbic acid), vitamin B group, vitamin E (tocopherol), vitamin A, D, K, and riboflavin butyrate. The vitamin B group includes vitamin B1, vitamin B1 derivatives, vitamin B2, vitamin B6, vitamin B12, and various vitamin B complexes such as biotin, pantothenic acid, nicotinic acid, and folic acid. Vitamin B1 and its derivatives include thiamine or salts thereof, thiamine disulfide, fursultiamine or salts thereof, dicetiamine, bisbuthiamine, bisbenchamine, benfotiamine, thiamine monophosphate disulfide, chicotiamine, octothiamine, prosulfur All compounds having bioactivity of vitamin B1 such as thiamine are included.

  Examples of the mineral include calcium, magnesium, zinc, and iron.

  Examples of the dietary fiber include gums, mannan, pectin, hemicellulose, lignin, β-glucan, xylan, and arabinoxylan.

  Examples of the surfactant include glycerin fatty acid ester, sorbitan fatty acid ester, and sucrose fatty acid ester.

  Examples of the excipient include sucrose, glucose, corn starch, calcium phosphate, lactose, dextrin, starch, crystalline cellulose, and cyclodextrin.

  Examples of other active ingredients having the antidepressant or anxiolytic action include, for example, tricyclic antidepressants, tetracyclic antidepressants, triazolopyridine antidepressants, selective serotonin reuptake inhibitors (SSRI). , Commonly used antidepressants such as serotonin and noradrenaline reuptake inhibitors (SNRI), and commonly used anxiolytics such as benzodiazepine, thienodiazepine and diphenylmethane anxiolytics It is done.

  Other than the above, for example, taurine, glutathione, carnitine, creatine, coenzyme Q, α-lipoic acid, glucuronic acid, glucuronolactone, theanine, γ-aminobutyric acid, capsaicin, various organic acids, flavonoids, polyphenols, catechins Further, indigestible oligosaccharides such as xanthine derivatives and fructooligosaccharides, polyvinylpyrrolidone and the like may be added as additives. The amount of these additives is appropriately determined according to the type of additive and the amount of intake to be desired, but is generally in the range of 0.01 to 30% by mass, preferably 0.1 to 20% by mass. %, More preferably in the range of 0.1 to 10% by mass.

  When preparing a medicament containing the peptide of the present invention or a salt thereof, it is usually prepared as a composition comprising the peptide of the present invention or a salt thereof as an active ingredient and a pharmaceutically acceptable carrier. A pharmaceutically acceptable carrier generally refers to an inert, non-toxic, solid or liquid, bulking agent, diluent or encapsulating material that does not react with the peptides of the invention or salts thereof. Examples thereof include water, ethanol, polyol (for example, glycerol, propylene glycol, liquid polyethylene glycol and the like), a suitable mixture thereof, a solvent such as vegetable oil, a dispersion medium, and the like. The medicament may further contain the above-mentioned additives, active substances, other active ingredients having antidepressant or anxiolytic action, and the like.

  The pharmaceutical dosage form is not particularly limited, and is an oral dosage form such as a tablet, pill, granule, powder, fine granule, powder, capsule, syrup, drink, liquid, liquid food, or sublingual Arbitrary dosage forms such as tablets, nasal sprays, suppositories, parenteral dosage forms such as injections can be used.

  Examples of the administration method of the pharmaceutical include oral administration and administration methods generally used for pharmaceutical administration, such as intravenous administration, intramuscular administration, and subcutaneous administration. In addition, it is possible to adopt an administration method in which it is absorbed from mucous membranes other than the digestive tract, such as the rectum, sublingual, and intranasal. can do.

  The content of the peptide of the present invention or a salt thereof in the above medicament varies depending on the dosage form, but is usually 0.001 to 99% by mass, preferably 0.01 to 90% by mass, based on the dry mass of the peptide of the present invention. %, More preferably in the range of 1 to 85% by mass, still more preferably in the range of 5 to 80% by mass. The medicament is desirably in a dosage form in which the daily dose can be controlled so that the daily dose of the peptide of the present invention or a salt thereof described later can be achieved.

  When preparing a food or feed containing the peptide of the present invention or a salt thereof, the form is not particularly limited. The food or feed of the present invention includes beverages. In addition, the food or feed of the present invention contains the peptide of the present invention or a salt thereof as an active ingredient, and is intended to prevent or ameliorate the above-mentioned depressive symptoms and / or anxiety symptoms. Health foods, functional foods, foods for specified health use, foods for sick people, pets, feeds for domestic animals, racehorses, appreciation animals, and pet foods are included.

  For example, the health food and functional food of the present invention specifically include various kinds such as tablets, pills, granules, powders, fine granules, powders, capsules, syrups, drinks, liquids, and liquid foods. It can be in the form of a preparation. The food in the form of a preparation can be produced in the same manner as the above-mentioned medicine. For example, after adding an appropriate excipient (for example, starch, processed starch, lactose, glucose, water, etc.), conventional means are used. Can be manufactured. Furthermore, as specific examples of the food of the present invention, coffee beverage, tea beverage, fruit juice beverage, soft drink, milk beverage, butter, mayonnaise, shortening, margarine, various salad dressings, breads, noodles, cooked rice, pasta, Examples include sauces, confectionery, cookies, chocolate, candy, chewing gum, various seasonings, and various diet products. Or the foodstuff of this invention can also be prepared by adding the peptide of this invention, or its salt to arbitrary normal foodstuffs.

  The content of the peptide of the present invention or the salt thereof in the food of the present invention varies depending on the form of the food, but is usually 0.01 to 80% by mass, preferably 0.1 to 80% by mass, based on the dry mass of the peptide of the present invention. It is 75 mass%, More preferably, it is 1-70 mass%, More preferably, it is the range of 5-70 mass%. Since the peptide of the present invention or a salt thereof is highly safe, its content can be further increased. It is desirable that the food is in a form in which the daily intake can be controlled so that the daily dose of the peptide of the present invention or a salt thereof described later can be achieved.

  Since the feed can be used in almost the same composition and form as the food, the description regarding the food of the present invention in the present specification can be similarly applied to the feed of the present invention.

  When the peptide of the present invention or a salt thereof is used as an antidepressant or anxiolytic agent, the dose may be an amount that can provide a desired antidepressant effect or anxiolytic effect. It can be appropriately determined according to the form, species of the individual to be administered or ingested, symptoms, age, sex and the like. For example, the daily dose for an adult is usually in the range of 0.001 to 1 g as the mass of the peptide of the present invention, and 0.01 to 1 g in the case of oral administration. Furthermore, when the peptide used in the present invention is prepared by partially hydrolyzing a natural protein, the dose can be further increased because it is highly safe derived from a natural product. It is desirable to increase or decrease the dose appropriately while observing the effect. Although the daily dose can be administered or ingested once, it is desirable to administer or ingest several times.

  The peptide of the present invention or a salt thereof, which is an active ingredient of the antidepressant or anxiolytic agent of the present invention, can be prepared from natural proteins typified by wheat. Therefore, long-term continuous intake is possible. Therefore, the antidepressant or anxiolytic agent of the present invention is applicable not only to healthy humans and animals, and adults and adult animals, but also to children, elderly people, young or elderly animals, or sick humans and animals. Can be used safely and continuously.

  EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to a following example.

Example 1 Synthesis of PyroGlu-Leu Synthesis was performed by a liquid phase method using the Boc method.
(1) Condensation reaction between Boc-pyroGlu and HCl Leu-O ^t Bu In an eggplant-shaped flask, HCl Leu-O ^t Bu (390 mg) was placed and dissolved in 5 mL of DMF, and then cooled with ice and 0.124 mL of triethylamine was added. Next, Boc-pyroGlu-OH (400 mg), HOBt (470 mg), and WSCD HCl (367 mg) were added, and the mixture was subjected to a condensation reaction by stirring for 12 hours under ice cooling. After completion of the reaction, the pressure was reduced and DMF was distilled off. The residue was dissolved in ethyl acetate, and then washed with ethyl acetate in the order of 5% aqueous sodium hydrogen carbonate solution, 10% aqueous citric acid solution, water and saturated brine, and then anhydrous sulfuric acid. Dried over sodium. Sodium sulfate was filtered off, and the filtrate was concentrated under reduced pressure. Ether-hexane was added to the resulting residue to solidify and collect Boc-pyroGlu-Leu-O ^t Bu. The yield was 609 mg, and the yield was 88%.
(2) obtained in the deprotection the ^{Boc-pyroGlu-Leu-O t} Bu a (600 mg) taken up in an eggplant-shaped flask, and dissolved by addition of trifluoroacetic acid 5 mL, 1 hour, allowed to deprotection reaction under ice-cooling It was. Trifluoroacetic acid was removed with N ₂ gas, and the deprotected peptide was solidified by adding ether, and then collected by filtration. The obtained solid was dissolved in 4N HCl / dioxane, ether was added to solidify again, and the mixture was collected by filtration. The yield was 220 mg and the yield was 53%.

(Test Example 1) Forced swimming test The forced swimming test is a test in which an animal is placed in a water tank where it cannot escape and a depression is caused from its hopeless state. In this test, the amount of time (immobility time) that gives up swimming and floats in the water is taken as an index of depression, and when this time increases, it is judged as depressed and when it is shortened, it is judged as antidepressant. Forced swim testing is a reliable and specific screening method for antidepressants, as immobility time is reduced by the administration of many antidepressants and is also highly correlated with clinical dose. It is considered a law.
As animals, ddY male mice (body weight 22-28 g) were used as 6 animals per group. The peptide of Example 1 was dissolved in water and administered intraperitoneally at a dose of 1, 3, 10, 30 mg / kg or orally at a dose of 3 mg / kg. Thirty minutes after the administration, water was added to a water tank having a diameter of 10 cm and a depth of 19.5 cm to a water depth of 9.5 cm, animals were added one by one, and behavior for 6 minutes was observed. As a control group, a group in which only water was intraperitoneally administered was set. The results are shown in Table 1 with the immobility time (seconds) in 6 minutes averaged for each group.

(Test Example 2) Forced swimming test A test was performed in the same manner as Test Example 1. The peptide of Example 1, pyroglutamic acid, leucine or glutamyl leucine 10 mg / kg each was intraperitoneally administered, and the immobility time was measured. The results are shown in Table 2.

(Test Example 3) Elevated plus maze test The elevated plus maze test is a method of evaluating anxiety levels using the search behavior of animals at high altitude as an index. In this test, placed in a high place, placed on a cross maze with two walls with transparent walls (closed arms) and the other two with no walls (open arms) Observe animal behavior. Animals in this study environment are considered to have undergone biological changes to anxiety and fear similar to humans. Since animals cause anxiety particularly in the open arm, it is determined that an animal having a low frequency of entry into the open arm and staying time is anxious, and an animal having a large amount of time is anxious. This elevated plus maze test is supported as a highly relevant method for evaluating anxiety-related behavior, and it can be easily measured for anxiety levels, so it is widely used as a screening method for anxiolytic drugs. ing.
The elevated labyrinth test apparatus used a cross road with each arm having a length of 25 cm and a width of 5 cm. The height of the crossroad was 50 cm, and transparent walls were installed on both sides of the closed arm.
As animals, ddY male mice (body weight 24-27 g) were used as 14-15 mice per group. The peptide of Example 1 was dissolved in water and administered intraperitoneally at doses of 1, 3, 10 mg / kg. Thirty minutes after administration, animals were placed one by one in the center of the elevated maze testing apparatus and observed for 5 minutes. The total number of times of entry into both travel paths of the open arm and the closed arm per 5 minutes was obtained, and the entry rate into the closed arm was calculated by the following formula. As a control group, a group in which only water was intraperitoneally administered was set. The results are shown in Table 3 as the average value of each group.

Approach rate (%) = (Number of times of entry into the open arm / Total number of times of entry into the travel path of both the open arm and the closed arm) x 100

Claims (8)

The following formula:
pyroGlu- (X) n- Leu
(Wherein, X is Gl n, n is an integer of 0 or 1)
An antidepressant or anxiolytic agent comprising at least one selected from the group consisting of a peptide consisting of the amino acid sequence represented by the formula: agent according to claim 1 n is 0. The agent according to claim 1 or 2 , which is an anxiolytic agent. The agent according to claim 1 or 2, which is an antidepressant and anxiolytic agent. The following formula:
pyroGlu- (X) n-Leu
(Wherein X is Gln and n is an integer of 0 or 1)
A food composition for antidepressant or anti-anxiety comprising, as an active ingredient, at least one selected from the group consisting of a peptide consisting of the amino acid sequence represented by the formula: 6. The food composition according to claim 5, wherein n is 0. The food composition according to claim 5 or 6, which is an anti-anxiety food composition. The food composition according to claim 5 or 6, which is an antidepressant and anxiolytic food composition.