WO2021015222A1 - Peptide - Google Patents

Abstract

The purpose of the present invention is to provide a peptide having an action such as a strong blood pressure lowering action. Specifically, a peptide having an amino acid sequence of KFWGK (SEQ ID NO: 1) is provided.

Description

peptide

The present invention relates to peptides. The present invention also relates to pharmaceutical compositions, antihypertensive agents, antifeedant agents and foods containing the peptides.

Hypertension is called a silent killer because it causes death-related diseases such as stroke and myocardial infarction, and it is required to prevent and treat it.

Many physiologically active peptides showing various physiological actions have been found in the enzyme digested products of food proteins. It is known that the onset of atherosclerosis is triggered by a decrease in the function of blood vessels, particularly vascular endothelium, and the function of bioactive peptides on blood vessels has attracted attention.

The gastrointestinal tract is an interface that separates the external environment (inside the lumen) and the internal environment (inside the body), and plays a role in preventing the invasion of pathogens and foreign substances and digesting nutrients and absorbing them in the body. Furthermore, it has become clear that the gastrointestinal tract receives information in the lumen, transmits that information into the body, and interacts with various regulatory systems such as the circulatory system, endocrine system, and nervous system. .. However, the number of molecular species produced in the digestive tract by ingestion of food is enormous, and the details of its acceptance mechanism have been unknown.

Patent Document 1 and Non-Patent Documents 1 and 2 disclose peptides having actions such as feeding suppression, anti-obesity, arterial relaxation, blood pressure lowering, and prevention of metabolic syndrome.

International Publication WO2012 / 070554 JP-A-2018-184367

Kagebayashi T et al. Mol Nutr Food Res. 2012 Sep; 56 (9): 1456-63. Kontani Net al. Mol Nutr Food Res. Mol Nutr Food Res. 2014 Feb; 58 (2): 359-64. Sasai Met al. Biochem Biophys Res Communi. 2018 Sep 5; 503 (2): 1070-1074.

In Patent Document 2 and Non-Patent Document 3, in order to systematically examine the molecules received by the gastrointestinal tract, the responsiveness to enteroendocrine cells was examined using a dipeptide library, and Phe-Trp (FW) was high. It is disclosed that it exhibits reactivity.

An object of the present invention is to provide a peptide having an action such as lowering blood pressure, which is higher than that of a conventional peptide.

The present inventor has made extensive studies to solve the above problems, and found that a peptide having an amino acid sequence of KFWGK (SEQ ID NO: 1) has a high blood pressure lowering effect. The present invention has been completed by further studying based on such findings.

That is, the present invention includes the following aspects.

Item 1, a peptide having the amino acid sequence of KFWGK (SEQ ID NO: 1).

A pharmaceutical composition containing the peptide according to Item 2 and Item 1 as an active ingredient.

A blood pressure lowering agent containing the peptide according to Item 3 and Item 1 as an active ingredient.

An eating inhibitor containing the peptide according to Item 4 and Item 1 as an active ingredient.

Foods containing the peptides according to items 5 and 1.

A food product to which the peptide according to Item 5-1 and Item 1 is added.

Item 6, the food according to item 5 or item 5-1 for lowering blood pressure.

Item 7, the food according to item 5 or item 5-1 for suppressing feeding.

A method for lowering blood pressure and / or suppressing feeding behavior, which comprises a step of administering the peptide according to item 8 or 1 to a patient or a preliminary group in need.

Item 9. The peptide according to Item 1, for lowering blood pressure and / or suppressing feeding behavior.

Item 10. Use of the peptide according to Item 1 for producing a drug or food for lowering blood pressure and / or suppressing feeding behavior.

The pharmaceutical composition and food containing the peptide of the present invention as an active ingredient have a high blood pressure lowering effect, have few side effects, and are suitable for long-term administration. Furthermore, it also has an antifeedant effect. Moreover, the pharmaceutical composition and food of the present invention are particularly effective for oral administration.

Furthermore, natural short-chain peptides can be ingested as foods, and it can be expected that hypertensive individuals ingesting them as foods will prevent diseases such as arteriosclerosis. It is also effective in preventing metabolic syndrome.

Evaluation result of blood pressure lowering effect Effect of inhibitors on blood pressure lowering effect Effect of inhibitors on arterial relaxation Expected mechanism of action

The peptide of the present invention is a peptide (dipeptide) having a 5-residue amino acid sequence of KFWGK (SEQ ID NO: 1).

In another aspect of the invention, the peptide of the invention is a peptide comprising 5 residues of KFWGK (SEQ ID NO: 1) or an amino acid sequence. In this embodiment, an amino acid residue can be added to the N-terminal side and / or the C-terminal side (preferably the C-terminal side) as long as the amino acid sequence is contained. The number of amino acid residues to be added is not limited, and may be about 20 amino acid residues, preferably about 10 amino acid residues, more preferably about 5 amino acid residues, and further preferably 4, 3, 2, or 1 amino acid. be able to.

Further, one or more amino acid residues (for example, 2 or 3), preferably 1 amino acid residue in the above amino acid sequence can be substituted as long as the effect of the present invention is not impaired. Further, one or more amino acid residues (for example, 2 or 3), preferably 1 amino acid residue in the above amino acid sequence can be inserted as long as the effect of the present invention is not impaired. Further, one or more amino acid residues (for example, 2 or 3), preferably 1 amino acid residue in the above amino acid sequence can be deleted as long as the effect of the present invention is not impaired.

The amino acid residue to be added may be a natural amino acid or an unnatural amino acid. Natural amino acids include alanine, arginine, aspartic acid, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine proteins. It contains the constituent amino acid residues as well as other amino acid residues such as selenocysteine, N-formylmethionine, pyrrolicin, and pyroglutamine.

The amino acids that make up the peptide are either L-form amino acids, D-form amino acids, or DL-form amino acids (if the amino acids are a mixture of D-form and L-form, either the racemic form or the amino acid in which one of the enantiomers is excessive. Included) can be used. Peptides consisting of only L-form amino acids or only D-form amino acids, particularly peptides consisting of only L-form amino acids are preferable.

Further, when the peptide used in the present invention contains two or more asymmetric carbons, it can be in any form of each enantiomer or diastereomer or a mixture thereof in any ratio. Separation of enantiomers or diastereomers can be performed by a method using a normal column, a method using an optically active column, a method of introducing an optically active group and optical resolution in the form of a derivative, and then removing the optically active group. Any known method can be used, such as a method of forming a salt with an optically active acid or base and performing optical resolution.

Peptides can have modifications. The amino terminus (N-terminus) of the peptide may be a free amino group (NH _2- ) or one having a modification such as an acetyl group (CH ₃ CO-). The carboxy terminus (C-terminus) of the peptide may be a free carboxyl group (-COOH) or one having a modification such as an amide group. The amino acid residue of the peptide may be unmodified or may have a modification such as a phosphate group or a sugar chain.

The peptide of the present invention may be a salt (acid addition salt or base salt). Acid addition salts include inorganic salts such as hydrochloric acid, sulfuric acid, nitrate, phosphoric acid, hydrobromic acid and perchloric acid, citric acid, succinic acid, maleic acid, fumaric acid, malic acid, tartaric acid and p-toluenesulfonic acid. , Salts of organic acids such as benzenesulfonic acid, methanesulfonic acid, trifluoroacetic acid and the like. Examples of the base salt include alkali metal salts such as sodium, potassium and lithium, and alkaline earth metal salts such as calcium and magnesium.

The peptide of the present invention may be a solvate. Solvates include water (in the case of hydrates), methanol, ethanol, isopropanol, acetic acid, tetrahydrofuran, acetone, dimethylformamide, dimethylsulfoxide, dimethylacetamide, acetamide, ethylene glycol, propylene glycol, dimethoxyethane and the like. Things can be mentioned.

The peptide of the present invention can be obtained by chemical synthesis such as a peptide synthesis method. That is, in the liquid phase method or the solid phase method, which is a method usually used for peptide synthesis, a method using an active ester such as HBTU for a raw material having a reactive carboxyl group and a raw material having a reactive amino group, or a carbodiimide It can be condensed by a usual method in peptide synthesis such as a method using a coupling agent such as. If the condensate produced has a protecting group, it can also be produced by removing the protecting group.

Functional groups that should not be involved in the reaction in this reaction step are protected by protecting groups. Examples of the amino-protecting group include benzyloxycarbonyl (CBZ), t-butyloxycarbonyl (Boc), 9-fluorenylmethyloxycarbonyl (Fmoc) and the like. Examples of the carboxyl group protective agent include groups capable of forming an alkyl ester, a benzyl ester, etc. In the case of the solid phase method, the C-terminal carboxyl group is a chlorotrityl resin, a chloromethyl resin, an oxymethyl resin, p-. It is bound to a carrier such as an alkoxybenzyl alcohol resin. The condensation reaction is carried out in the presence of a condensing agent such as carbodiimide or with an N-protected amino acid active ester or peptide active ester.

After the condensation reaction is completed, the protecting group is removed, but in the case of the solid phase method, the bond between the C-terminal of the peptide and the resin is further cleaved. Furthermore, the peptides of the invention are purified according to conventional methods. Examples thereof include ion exchange chromatography, reverse phase liquid chromatography, affinity chromatography and the like. The synthesis of the synthesized peptide is analyzed by a protein sequencer, GC-MS, etc., which reads the amino acid sequence from the C-terminal by the Edman degradation method.

The peptide of the present invention can also be synthesized by an enzymatic method (see WO2003 / 010307).

The peptides of the present invention have a strong blood pressure lowering effect and an arterial relaxing effect. As shown in Examples described later, these effects are suppressed by lorglumide, which is an antagonist of CCK ₁ receptor, and thus these effects are considered to be mediated by activation of CCK ₁ receptor.

Since the peptide of the present invention has a blood pressure lowering effect and an arterial relaxing effect, it can be administered to a hypertensive patient or the like who needs a blood pressure lowering effect. In particular, it is possible to target patients in the late stage of hypertension in which the action of some therapeutic agents (for example, those exhibiting arterial relaxation action via NO) is attenuated.

It is understood that the stage of progression of hypertension progresses from the onset of hypertension to the late onset of hypertension over time. It is understood that the early stage of hypertension preferably refers to a stage in which the function of vascular endothelial cells, particularly the function of producing nitric oxide, which is a relaxing factor derived from vascular endothelium, is maintained. It is understood that the late stage of hypertension onset refers to a stage in which hypertension progresses more than the early stage of hypertension onset, and the function of vascular endothelial cells is preferably reduced as described above.

Further, since the peptide of the present invention has an action of promoting the release of the endogenous antifeedant peptide CCK, an antifeedant effect can be expected. The peptide of the present invention is an action mediated by the endogenous feeding inhibitory peptide CCK that promotes postprandial satisfaction, and can be expected to exhibit a natural feeling of fullness.

Therefore, the peptide of the present invention has an action of suppressing obesity through a blood pressure lowering action, an arterial relaxing action, an eating inhibitory action and an eating inhibitory action, and is also effective in preventing arteriosclerosis, and is effective in preventing metabolic syndrome. Effective for prevention. It has been reported that CCK responsiveness is reduced in patients with metabolic syndrome, and from this point of view, it is more suitable as a preventive agent for metabolic syndrome.

The peptide of the present invention can be provided as a pharmaceutical composition or a food (food composition).

The administration route of the peptide of the present invention or a product containing the same is not particularly limited, and oral administration, parenteral administration (for example, intramuscular or intravenous), intrarectal administration and the like can be adopted. Of these, oral administration or rectal administration, particularly oral administration, is preferable from the viewpoint of high effect.

The dose of this peptide varies depending on the administration method, the condition and age of the person to be administered. The dose is usually 0.01 mg / kg to 500 mg / kg, preferably 0.05 mg / kg to 100 mg / kg, more preferably 0.1 to 30 mg / kg per day for the patient or adult in the reserve group in need. Is. The peptide (active ingredient) of the present invention can be administered in the form of a pharmaceutical composition prepared by mixing with a carrier for preparation. As the carrier for preparation, a substance that is commonly used in the field of preparation and does not react with the peptide of the present invention is used.

The peptide of the present invention can be used as a medicine or food by itself. Tablets (uncoated tablets, sugar-coated tablets, effervescent tablets, film-coated tablets, chewable tablets, etc.), capsules Hard capsules and soft capsules using the peptides of the invention alone or with suitable non-toxic carriers, diluents or excipients. Including any of. ), Trochess, powders, fine granules, granules, liquids, suspensions, emulsions, pastes, creams, injections (including when blended in infusions such as amino acid infusions and electrolyte infusions), or enteric It can be used as a food or pharmaceutical preparation such as a sustained-release preparation such as tablets, capsules and granules.

One embodiment of the present invention includes a pharmaceutical composition containing the peptide of the present invention and a diluent, carrier, or excipient recognized as a pharmaceutical product. Another embodiment includes foods containing the peptides of the invention (eg, which can be contained by addition).

The content of the peptide in the drug or food can be appropriately selected, but is generally in the range of 0.01 to 100% by weight.

Specifically, examples of substances such as pharmaceutical or oral carriers, diluents or excipients that can be added to pharmaceuticals or foods include lactose, glucose, mannites, dextrin, cyclodextrin, starch, sucrose. , Magnesium aluminometasilicate, synthetic aluminum silicate, sodium carboxymethyl cellulose, hydroxypropyl starch, carboxymethyl cellulose calcium, ion exchange resin, methyl cellulose, gelatin, arabic rubber, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, polyvinylpyrrolidone, polyvinyl alcohol, light Silica anhydride, magnesium stearate, talc, tragant, bentonite, bee gum, titanium oxide, sorbitan fatty acid ester, sodium lauryl sulfate, glycerin, fatty acid glycerin ester, purified lanolin, glycerogelatin, polysorbate, macrogol, vegetable oil, wax, liquid paraffin , White vaseline, fluorocarbon, nonionic surfactant, propylene glycol, water and the like.

Examples of the dosage form include tablets, capsules, granules, powders, syrups, suspensions, suppositories, ointments, creams, gels, patches, inhalants, injections and the like. These formulations are prepared according to conventional methods. The liquid preparation may be dissolved or suspended in water or another suitable solvent at the time of use. Further, tablets and granules may be coated by a well-known method. In the case of an injection, the peptide of the present invention is prepared by dissolving it in water, but it may be dissolved in physiological saline or glucose solution as needed, or a buffer or preservative may be added. Good.

These preparations can contain the peptide of the present invention in a proportion of 0.01% to 100% by weight, preferably 1 to 90% by weight. These formulations may also contain other ingredients of therapeutic value.

To produce a solid preparation for oral administration, the active ingredient and excipient ingredients such as lactose, starch, crystalline cellulose, calcium lactate, silicic anhydride, etc. are mixed to form a powder, or sucrose, if necessary. A binder such as hydroxypropyl cellulose or polyvinylpyrrolidone, a disintegrant such as carboxymethyl cellulose or carboxymethyl cellulose calcium is added, and wet or dry granulation is performed to obtain granules. In order to produce tablets, these powders and granules may be tableted as they are or by adding a lubricant such as magnesium stearate or talc. These granules or tablets should be coated with an enteric solvent base such as hydroxypropylmethylcellulose phthalate or methacrylic acid-methylmethacrylic acid polymer to make an enteric solvent preparation, or coated with ethyl cellulose, carnauba wax, cured oil, etc. to make a long-acting preparation. You can also. To manufacture capsules, hard capsules are filled with powders or granules, or the active ingredient is used as it is or dissolved in glycerin, polyethylene glycol, sesame oil, olive oil, etc. and then coated with a gelatin film to form soft capsules. Can be done.

To produce a liquid preparation for oral administration, the active ingredient and sweeteners such as sucrose, sorbitol, and glycerin are dissolved in water to make a transparent syrup, and then essential oil, ethanol, etc. are added to make an elixir. Arabia gum, tragant, polysorbate 80, sodium carboxymethyl cellulose and the like may be added as an emulsion or a suspending agent. If desired, a flavoring agent, a coloring agent, a preservative and the like may be added to these liquid preparations.

Specific forms of foods that can be prepared by adding or blending the peptides according to the present invention include, for example, beverages (coffee, cocoa, juice, soft drinks, mineral drinks, tea drinks, green tea, tea, Karyu tea, dairy drinks). , Lactic acid drinks, yogurt drinks, carbonated drinks, other non-alcoholic drinks, alcoholic drinks, etc.), confectionery (hard candy, gum, gummy, jelly, pudding, mousse, cake, candy, cookies, crackers, biscuits, chocolate, ice cream ( Ice cream, ice candy, sherbet, shaved ice, etc.), sprinkles, dressings, seasonings, processed soybean foods (tofu, miso, soy sauce, yuba, kina flour, natto, etc.), processed meat foods (hamburger, meat loaf, meat balls, etc.) Tsukune, etc.), processed fish meat foods (kamaboko, chikuwa, etc.), retort foods, jelly-like foods (jelly, agar, jelly-like beverages, etc.), etc. can be mentioned. Foods that can be prepared by adding or blending the peptides of the present invention include so-called health foods, functional foods, foods with functional claims, nutritional supplements, supplements, foods for specified health use, foods for the sick, and combinations for the sick. It may be a food (Ministry of Health, Labor and Welfare, a type of special purpose food) or a food for the elderly (Ministry of Health, Labor and Welfare, a type of special purpose food), uncoated tablets, film-coated tablets, sugar-coated tablets, granules, powders, tablets, capsules (hard capsules and soft capsules). It can also be a chewable type, a syrup type, a drink type, etc. The food containing and blending the peptide according to the present invention can be prepared by a method known per se.

The food containing the peptide of the present invention can be produced, for example, by adding the peptide of the present invention to a known food. Specific forms of foods that can be produced by adding the peptide according to the invention include, for example, beverages (coffee, cocoa, juice, soft beverages, mineral beverages, tea beverages, green tea, tea, Karyu tea, dairy beverages, lactic acid bacteria beverages). , Yogurt drinks, carbonated drinks, other non-alcoholic drinks, alcoholic drinks, etc.), confectionery (hard candy, gum, gummy, jelly, pudding, mousse, cake, candy, cookies, crackers, biscuits, chocolate, ice cream, ice cream, Ice candy, sherbet, shaved ice, etc.), sprinkles, dressings, seasonings, dairy products (milk, processed milk, cream, butter, cheese, whey, ice creams, brick milk, powdered milk, fermented milk (Yogurt, etc.), lactic acid bacteria beverages, dairy beverages, etc.), processed soybean foods (tofu, miso, soy sauce, yuba, kina flour, natto, etc.), processed meat foods (hamburger, meat loaf, meat balls, tsukune, etc.) (Kamaboko, chikuwa, etc.), retort foods, jelly-like foods (jelly, agar, jelly-like beverages, etc.) and the like can be mentioned. The food containing the peptide according to the present invention can be prepared by a method known per se.

In addition, when the food containing the peptide of the present invention is made from a product containing bovine serum albumin such as milk and whey, the present invention can be made by including a step of hydrolysis with satilysin in the method for producing the food. A food containing the peptide of the invention can be produced. In another aspect, the food containing the peptide of the present invention can also be produced by including a step of producing the peptide of the present invention such as freeze-drying, acid and / or alkali treatment in the method for producing the food.

Foods containing the peptides of the present invention include so-called health foods, foods with functional claims, foods for specified health use, nutritional supplements, supplements, foods for the sick, combination foods for the sick (Ministry of Health, Labor and Welfare, a type of special purpose food) or It can be used as food for the elderly (Ministry of Health, Labor and Welfare, a type of special-purpose food).

Next, the present invention will be described in more detail with reference to Examples. However, the examples below do not limit the scope of the invention.

<Method>
The evaluation of the hypotensive effect, the calcium responsiveness test of enteroendocrine cells, and the arterial relaxation experiment were carried out according to the methods described in Patent Document 1 and Non-Patent Document 1.
(Evaluation of blood pressure lowering effect)
(i) Animals used Male rats with spontaneous hypertension (SHRs / Izm) (manufactured by SLC Japan, Inc.) were used. SHR rats were housed in a room controlled by a light-dark cycle of 23 ± 1 ° C., 50% humidity, and 12 hours / 12 hours. The feed was a solid SP feed (manufactured by Funabashi Farm Co., Ltd.) and was allowed to be freely ingested with water. As SHR rats, rats older than 25 weeks were used. In SHR rats, some antihypertensive agents are less likely to be effective after 25 weeks of age, and are considered to correspond to the advanced stage of hypertension.

(ii) Non-invasive blood pressure measurement experiment (Tail-cuff method)
Systolic blood pressure was measured by the Tail-cuff method in unanesthetized SHR rats. Blood pressure was measured using MK-2000 (manufactured by Muromachi Kikai Co., Ltd.). Animals trained with the Tail-cuff device for about 3 weeks were used in this experiment. Each sample was dissolved in physiological saline and forcibly orally administered using a metal sonde. Blood pressure was measured immediately before administration and after the elapsed time from administration shown in each table (2 hours, 4 hours, 6 hours, 24 hours, 48 hours).

The evaluation was performed by calculating the change in systolic blood pressure (ΔSystolic blood pressure) with respect to immediately before administration.

(Arterial relaxation experiment)
The mesenteric artery was removed from the euthanized SHR rat and spirally incised to prepare a specimen. Krebs-Henseleit nutrient solution ((120 mM NaCl, 4.7 mM KCl, 1.2 mM sulfonyl ₄ , 1.2 mM KH2PO 4, 2.5 mM CaCl ₂ , 25 mM NaHCO ₃ , 10 mM glucose), 37 ° C., This sample was suspended in a Magnus tube filled with 5% CO ₂ and 95% O ₂ mixed gas saturation), and the change in tension (tension) was recorded on a polygraph via a strain transducer (manufactured by Sanei).

The artery was contracted in advance with phenilephrine, a sample was added when it became stable, and the degree of relaxation was measured. The relaxation rate (Relaxation) was calculated by setting the degree of contraction when the artery was completely relaxed with papaverine as the ratio of the degree of contraction to 100%.

<Manufacturing example>

(peptide)
The peptide KFWGK (SEQ ID NO: 1) was synthesized by a conventional method.
(Statistical analysis)
The data obtained by the test was expressed as the sum of the mean (Mean) of the number of trials n and the standard error (Standard error of the mean (SEM)). The t-test was used for comparison between the two groups. For comparisons between three or more groups, the data were analyzed by one-way ANOVA, followed by a Tukey-Kramer test for multiple comparisons. When p <0.05 with respect to the control (Control) (“*” in the figure), it was judged that there was a significant difference.

<Experiments and results>
(Example 1: Blood pressure lowering effect (1))
The hypotensive effect was evaluated using SHR rats orally administered with the peptide KFWGK at 5.0 μg / kg (n = 5). Administration of only physiological saline as a solvent was used as a control (hereinafter, the same applies). The systolic blood pressure was measured by the Tail-cuff method at each time point 2 hours, 4 hours, 6 hours, 24 hours and 48 hours after the administration.

The results are shown in Fig. 1. The peptide KFWGK has a significant hypotensive effect when administered at a low dose of 5 μg / kg. Furthermore, the hypotensive effect lasts up to 24 hours after administration.

(Example 2: Blood pressure lowering effect (2))
The blood pressure lowering effect was evaluated when the CCK ₁ receptor antagonist (CCK ₁ R Antagonist) lorglumide was added in addition to the peptide KFWGK.

A solvent-only control (control), peptide KFWGK alone (peptide), peptide KFWGK in combination with rolglumid (peptide + CCK antagonist), and rolglumid alone (CCK antagonist) were administered by the Tail-cuff method at 4 hours after administration. Systolic blood pressure was measured (n = 7-8). The dose of the peptide KFWGK was 50 μg / kg, and the dose of rolglumid was 1 mg / kg.

The results are shown in Fig. 2. The hypotensive effect of the peptide KFWGK was inhibited by rolglumid. The peptide KFWGK is thought to exhibit a hypotensive effect due to its vasorelaxant effect, which is presumed to be a vasorelaxant effect mediated by activation of the CCK1 receptor.

(Example 3: Arterial relaxation experiment)
Using the peptide KFWGK as a test substance, the arterial relaxation effect was evaluated by arterial relaxation experiments in the presence or absence of various inhibitors (n = 1).

The peptide KFWGK 50 μg / kg was used as a sample. As the inhibitor to be used in combination, a CCK ₁ receptor antagonist (CCK ₁ R Antagonist), lorgumide (10 μM), and a cyclooxygenase inhibitor (COX Inhibitor), indomethacin (3 μM), were used. ..

When an inhibitor was used, the peptide KFWGK 50 μg / kg was administered after pretreatment with the inhibitor.

The results are shown in FIG. When lorglumide, an antagonist of the peptide CCK ₁ receptor, was added, the arterial relaxation effect was significantly inhibited. On the other hand, the addition of indomethacin, a COX inhibitor, did not reduce the relaxation rate. Therefore, the arterial relaxing action of the peptide KFWGK is considered to be mediated by the activation of the CCK ₁ receptor.

(Discussion)
The expected mechanism of action of the peptide KFWGK of the present invention is shown in FIG.

The peptide KFWGK of the present invention exhibits a CCK ₁ receptor-mediated arterial relaxation effect. In addition, since oral administration exerts a strong physiological effect and CCK secretion is performed by enteroendocrine cells, the peptide of the present invention has a point of action in both the blood vessel and the digestive tract, and the gastrointestinal tract is the central action. It is considered to be a point.

The arterial relaxation response in aged rats decreases, but in particular, peptides that exhibit an arterial relaxation effect via NO significantly attenuate the arterial relaxation response with aging. On the other hand, in aged rats, the reactivity of peptides showing arterial relaxation action via CCK does not decrease. That is, the blood pressure-lowering peptide that activates the CCK system is expected to effectively show a blood pressure-lowering effect even in an individual animal whose reactivity has decreased due to aging.

RF (minimum effective dose is 15 mg / kg, non-patent document 2 etc.) and FW (minimum effective dose is 1.5 mg / kg etc., non-patent document 3 etc.) have been reported as blood pressure lowering peptides via CCK. .. The peptide KFWGK of the present invention exhibits a hypotensive effect even at 5 μg / kg, exhibits a hypotensive effect at a lower dose than a conventionally known peptide, and exhibits a sustained effect over 24 hours. Moreover, since it activates the CCK system, it can be expected to show an effect even in aged rats in which some blood pressure-lowering substances are hard to show an effect. In addition, since 5-residue peptides with a large molecular weight show much stronger physiological activity when orally administered, it is considered that the contribution of the action mechanism that does not presuppose absorption is not small.

Claims (10)

A peptide having the amino acid sequence of KFWGK (SEQ ID NO: 1). A pharmaceutical composition containing the peptide according to claim 1 as an active ingredient. A blood pressure lowering agent containing the peptide according to claim 1 as an active ingredient. An antifeedant agent containing the peptide according to claim 1 as an active ingredient. A food containing the peptide according to claim 1. The food according to claim 5 for lowering blood pressure. The food according to claim 5 for suppressing eating. A method for lowering blood pressure and / or suppressing feeding behavior, which comprises a step of administering the peptide according to claim 1 to a patient or a preliminary group in need. The peptide according to claim 1, which lowers blood pressure and / or suppresses feeding behavior. Use of the peptide according to claim 1 for producing a drug or food for lowering blood pressure and / or suppressing feeding behavior.

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