JP5844528B2 - Blood insulin level increase inhibitor - Google Patents

Description

  The present invention relates to a blood insulin level increase inhibitor.

Insulin is a kind of peptide hormone secreted from pancreatic pancreatic β-cells and works to lower the elevated blood glucose level and keep it at a normal level. Major physiological actions include the promotion of sugar and amino acid uptake in muscle tissue, the promotion of protein synthesis, the promotion of sugar uptake and utilization in adipose tissue, the promotion of fat synthesis and the suppression of decomposition and combustion, the promotion of protein synthesis, etc. Is mentioned.
Insulin secretion is mainly promoted by glucose. When sugar is taken into the body by meals or the like and the blood glucose level (blood glucose concentration) rises, insulin is secreted to lower the increased blood glucose level, and the blood insulin concentration rises. Thus, it can be said that insulin secretion is very important in order to keep the blood sugar level constant and prevent diabetes.

  However, on the other hand, it is known that if insulin secretion due to a hyperglycemic state continues, a decrease in insulin sensitivity (insulin resistance) occurs in skeletal muscle, liver, and adipose tissue, which are target organs of insulin. When insulin resistance occurs, more insulin is secreted from the pancreas to compensate for the lack of hypoglycemic action. When such excessive secretion of insulin is repeated, the pancreas is eventually exhausted, and the secretory ability of insulin from the pancreatic β cells itself decreases. On the other hand, the insulin resistance of each target organ remains in an increased state. Thus, it is known that if a series of insulin action mechanisms in vivo does not function well, it will lead to a constitution that is likely to cause lifestyle-related diseases such as diabetes, and develop obesity, type II diabetes (hypertension), etc. (Non-Patent Document 1).

In the past, it has been considered that the amount of insulin secretion in blood changes depending on the blood sugar level, that is, the intake of carbohydrates. However, in recent years, it has been reported that an increase in blood insulin concentration is correlated with not only carbohydrate intake but also lipid intake (see Patent Document 1). According to Patent Document 1, it has been confirmed that when both saccharides and lipids are ingested, excessive insulin secretion exceeds the amount of insulin secretion when saccharides are ingested alone. Furthermore, it has also been confirmed that such excessive insulin secretion due to simultaneous intake of sugar and lipid is a factor highly correlated with obesity.
In recent years, the dietary habits of the Japanese have become westernized, changing from traditional carbohydrate-centered meals to meals with a high proportion of lipids. There are also concerns about an increase in lifestyle-related diseases and metabolic syndrome accompanying such changes in dietary habits. Therefore, preventing and improving the adverse health effects of high fat diets will be important in the future.

Conventionally, various attempts have been made to suppress the increase in blood glucose level from the viewpoint of preventing diabetes. For example, Patent Document 2 proposes a blood glucose level improving agent using polyglutamic acid in order to suppress an increase in blood glucose level. Polyglutamic acid is widely used as a moisturizing agent, absorbent and the like because of its high water-retaining ability, and has attracted attention as a biodegradable polymer. Further, it has been reported that there are an action of promoting calcium absorption from the small intestine, a blood pressure increase suppressing action, a saliva secretion promoting action, and a lipid absorption suppressing action (for example, see Patent Documents 3 to 6).
However, there is currently no active effort to suppress the increase in blood insulin level, and no effect on the blood insulin level increase related to a specific salt of polyglutamic acid has been reported so far. .

JP 2008-145136 A JP 2005-200330 A Japanese Patent Laid-Open No. 5-95767 JP 2008-255063 A Republished W2005 / 049050 JP 2009-173634 A

Modan M et al., J ClinInvest. 75 (3): 809-17, 1985.

An object of the present invention is to provide a blood insulin concentration increase inhibitor that suppresses an increase in blood insulin concentration after a meal. Another object of the present invention is to provide a blood insulin level increase inhibitor useful for preventing and improving obesity and diabetes caused by an increase in blood insulin level.
That is, an object of the present invention is to provide a blood insulin level increase inhibitor useful for pharmaceutical or food applications. Specifically, the present invention is useful as a pharmaceutical or non-pharmaceutical food for reducing, preventing, improving, alleviating or treating the risk of developing obesity or diabetes by suppressing an increase in post-meal insulin concentration. It is an object to provide a blood insulin level increase inhibitor.

  In view of the above problems, the present inventors have conducted intensive studies. As a result, the inventors have found that polyglutamic acid salt has an effect of suppressing an increase in blood insulin concentration after a meal. Furthermore, among the polyglutamic acid salts, the potassium salt was found to have a particularly excellent effect of suppressing an increase in blood insulin concentration. The present invention has been completed based on these findings.

  The present invention relates to a blood insulin level increase inhibitor comprising a potassium salt of polyglutamic acid as an active ingredient.

  The blood insulin level increase inhibitor of the present invention can suppress an increase in blood insulin level. Furthermore, the blood insulin level increase inhibitor of the present invention can adjust the insulin action mechanism in the body after meals to a normal range by suppressing an excessive increase in the level of insulin in the blood. Useful for prevention and improvement.

Hereinafter, the present invention will be described in detail.
The blood GIP concentration increase inhibitor of the present invention contains a potassium salt of polyglutamic acid as an active ingredient. Polyglutamic acid, in which the amino group of the carboxyl group and α-position of the γ-position of glutamic acid is a peptide bond, the formula is represented by (-NH-CH (COOH) -CH 2 -CH 2 -CO-) n However, the potassium salt of polyglutamic acid used in the present invention is one in which 50% or more of the hydrogen atoms of the carboxyl group in the above structural formula are substituted with potassium. The potassium salt of polyglutamic acid used in the present invention is preferably one in which 60% of the hydrogen atoms of the carboxyl group in the structural formula are replaced by potassium, and more than 70% of the hydrogen atoms of the carboxyl group, It is preferable that 80% or more, further 90% or more, further 95% or more, and especially 99% or more are substituted with potassium, but substantially all of the carboxyl groups are substituted with potassium. Particularly preferred. Moreover, it is preferable that the carboxyl group which will be located in the terminal in the said structural formula is also substituted with potassium.
The potassium salt of polyglutamic acid has an action of significantly suppressing an increase in blood insulin concentration compared to salts other than polyglutamic acid and its potassium salt. Therefore, the potassium salt of polyglutamic acid can be used as a blood insulin level increase inhibitor, and can also be used to produce the insulin level increase inhibitor. Until now, it has not been known that the potassium salt of polyglutamic acid has the effect of suppressing an increase in blood insulin concentration after a meal. In addition, it is not known that the potassium salt of polyglutamic acid has an effect of preventing or improving obesity. The potassium salt of polyglutamic acid used in the present invention has an effect of efficiently suppressing an increase in blood insulin concentration, as shown in Examples described later.

In the present invention, “suppressing increase in blood insulin concentration” means suppressing increase in blood insulin concentration mainly occurring after meals. The suppression of the increase in blood insulin concentration after a meal does not necessarily mean that the increase in blood insulin concentration caused after a meal is completely suppressed, and the blood insulin concentration increase inhibitor of the present invention is administered. It is a concept that also includes a moderation of the degree of increase in blood insulin concentration compared to the case where the blood insulin concentration is not.
In addition, the “inhibitory effect on the increase in blood insulin concentration” in the present invention includes an insulin secretion inhibitory effect that suppresses an increase in blood insulin concentration by suppressing insulin secretion from the pancreas, and a blood concentration by decreasing the blood insulin concentration. It is a concept that includes any of the insulin lowering actions that suppress the increase in intermediate insulin concentration.

The lipid is a lipid component contained in a general meal, and is not particularly limited as long as it enhances insulin secretion. Specifically, butter, lard, fish oil, corn oil, rapeseed oil, olive oil, sesame oil Etc.
The carbohydrate is a carbohydrate component contained in a general meal and is not particularly limited as long as it promotes insulin secretion. Specifically, cooked rice, starch, flour, sugar, fructose, glucose, Examples include glycogen.
In addition, it is known that when the carbohydrate is ingested with lipids, the increase in blood insulin concentration is promoted as compared with the case where the carbohydrate is ingested alone. The blood insulin level increase inhibitor of the present invention can also effectively suppress the rapid increase in blood insulin level caused when such lipids and carbohydrates are ingested together. Therefore, the blood insulin level increase inhibitor of the present invention can be used, for example, even when ingesting 5 g / 60 kg body weight or more of lipid and 10 g / 60 kg body weight or more of carbohydrate in one meal. The increase in concentration can be suppressed (closed) to a normal increase level.

As shown in the Examples below, the effect of suppressing the increase in blood insulin concentration of the potassium salt of polyglutamic acid used in the present invention is generally observed regardless of the molecular weight of the potassium salt of polyglutamic acid, but the weight average molecular weight is If it is too large, the effect tends to be low.
The weight average molecular weight of the polyglutamic acid potassium salt used in the present invention is preferably about 500 or more, more preferably 1,000 or more, still more preferably 2,000 or more. Is more preferably 5,000 or more, and particularly preferably 5,000 or more.
The upper limit of the weight average molecular weight of the polyglutamic acid potassium salt to be used is preferably about 5,000,000. However, the production inhibitor and the blood insulin level increase inhibitor of the present invention are considered as an oral liquid preparation. In view of ease of throat, sliminess, and ease of swallowing, it is preferable that the viscosity is relatively low. The weight average molecular weight of the potassium salt of polyglutamic acid used is 1,000,000 or less. More preferably, it is more preferably 500,000 or less.
The potassium salt of polyglutamic acid is remarkably higher than polyglutamic acid having a similar weight average molecular weight and metal salts other than the potassium salt within the range of 500 to 1,000,000 in weight average molecular weight. It exhibits an inhibitory effect on the increase in blood insulin concentration, and has a weight average molecular weight in the range of 1,000 to 800,000, more preferably in the range of 2,000 to 400,000, particularly in the range of 3000 to 200,000, and in particular 4, Within the range of 000 to 150,000, the blood insulin concentration increase suppressing effect that is conspicuous can be exhibited.
The weight average molecular weight can be measured, for example, by high performance liquid chromatography using a gel filtration column.

The potassium salt of polyglutamic acid used in the present invention is a polyglutamic acid or salt thereof produced by chemical synthesis or microorganisms, or a commercially available polyglutamic acid or salt thereof, as described in Examples below. It can be obtained by neutralizing with an aqueous potassium oxide solution. It can also be produced by microorganisms cultured in a mixed medium containing potassium. The optical activity of glutamic acid constituting the potassium salt of polyglutamic acid may be D-form, L-form, or a mixture thereof. Polyglutamic acid naturally glutamic acid is a polymer bound at position gamma, as the microorganism capable of producing poly glutamic acid in wild-type, for example, a portion of Bacillus (Bacillus) bacteria including Bacillus natto and its allied species ( Bacillus subtilis var. Chungkookjang , Bacillus licheniformis , Bacillus megaterium , Bacillus anthracis , Bacillus halodurans ), Natrialba aegyptiaca , Hydra, etc. [Ashiuchi, M., et al .: Appl. Microbiol. Biotechnol., 59, pp.9-14 (2002)]. Also, genetically as the production example of the polyglutamic acid with the engineering technique, about 9 g / L / 5 days in transgenic recombinant Bacillus subtilis at plasmid (Bacillus subtilis ISW1214 strain) [Ashiuchi, M., et al .: Biosci. Biotechnol. Biochem., 70, pp. 1794-1797 (2006)], about 4 g / L / 1.5 days in recombinant Escherichia coli transfected with a plasmid [Jiang, H., et al .: Biotechnol. Lett., 28, pp.1241-1246 (2006)] is known to be obtained. Alternatively, polyglutamic acid is commercially produced as a food additive, cosmetic material, thickener and the like, and polyglutamic acid supplied by domestic and overseas polyglutamic acid manufacturers can be purchased (for example, domestic manufacturers: Nippon Polyglu, Ichimaru Falcos, Meiji Food Materia, etc., overseas manufacturers: BioLeaders, etc.).

  The potassium salt of polyglutamic acid used in the present invention can suppress insulin secretion after ingesting carbohydrates, lipids and / or proteins, thereby suppressing an increase in blood insulin concentration. And the inhibitory effect is remarkably excellent compared with polyglutamic acid and other polyglutamate.

  The blood insulin level increase inhibitor of the present invention may be the potassium salt of polyglutamic acid itself. In addition, the blood insulin level increase inhibitor of the present invention is an appropriate liquid or solid excipient or extender such as titanium oxide, calcium carbonate, distilled water, lactose, starch, etc. in addition to the potassium salt of polyglutamic acid. May be included. In this case, the content of the potassium salt of polyglutamic acid is not particularly limited, but it is preferably 0.01 to 100% by mass, more preferably 0.1 to 95% by mass in the blood insulin level increase inhibitor. Preferably, 1 to 90% by mass is included, and 5 to 85% by mass is particularly preferable.

  When the blood insulin level elevation inhibitor of the present invention is used for foods, pharmaceuticals, etc., the potassium salt of polyglutamic acid alone to humans and animals, intragastrointestinal administration, intraperitoneal administration, intravascular administration, intradermal administration, In addition to administration by subcutaneous administration, etc., it can be ingested by blending into various foods, pharmaceuticals, pet foods and the like. As foods, in addition to general foods, the concept is to suppress the rise in blood insulin levels, reduce, prevent, improve, alleviate, and treat obesity and diabetes risk. It can be applied to foods such as sick foods and foods for specified health use. When used as a pharmaceutical, for example, oral solid preparations such as tablets and granules, and oral liquid preparations such as oral liquids and syrups can be used.

  In addition, when preparing an oral solid preparation, after adding excipients, binders, disintegrants, lubricants, coloring agents, flavoring agents, flavoring agents, etc., to the potassium salt of polyglutamic acid as necessary. Tablets, coated tablets, granules, powders, capsules and the like can be produced by conventional methods. Moreover, when preparing a liquid preparation for oral use, a liquid preparation, a syrup, an elixir, etc. can be manufactured by a conventional method by adding a corrigent, a buffer, a stabilizer, a corrigent and the like.

The blending amount of the potassium salt of polyglutamic acid in each food or preparation is not particularly limited, but is preferably 0.01 to 100% by mass, more preferably 0.03 to 90% by mass, and More preferably, it is contained in an amount of 1-80% by mass, particularly preferably 0.3-70% by mass, and particularly preferably 1-60% by mass.
The effective administration (intake) amount in each of the above foods and preparations is preferably 0.01 g / kg body weight to 1.0 g / kg body weight per day as a potassium salt of polyglutamic acid, preferably 0.003 g / kg body weight to The weight is more preferably 0.5 g / kg body weight, and still more preferably 0.01 g / kg body weight to 0.2 g / kg body weight. Further, the blood insulin level increase inhibitor of the present invention is effective when used before, during or after a meal, and is particularly preferably used before or during a meal, more preferably from 1 hour before the meal. preferable.
The subject of administration or ingestion is not particularly limited as long as it is a person in need thereof, but a person having a fasting blood glucose level of 100 mg / dL or more, or a fasting blood triglyceride value of 100 mg / dL or more is administered or It is preferable to be an intake target person.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to this.

[Analysis method]
Quantitative determination method and weight average molecular weight determination method-1 of polyglutamic acid potassium salt:
The quantitative determination of the potassium salt of polyglutamic acid and the measurement of the weight average molecular weight were carried out by gel filtration using a D-6000 (manufactured by Hitachi High-Technologies Corporation) HPLC system. The analysis conditions were TSKGel G4000PWXL and TSKGelG6000PWXL gel filtration columns (trade name, manufactured by Tosoh Corporation) as the analysis column, 0.1M sodium sulfate as the eluent, a flow rate of 1.0 mL / min, and a column temperature of 50 ° C. The UV detection wavelength was 210 nm. The concentration was calculated by preparing a calibration curve using polyglutamic acid having a molecular weight of 880 k (manufactured by Meiji Food Materia Co., Ltd.) as a standard product. In addition, the weight average molecular weight was determined by using pullulan (trade name: Shodex STANDARD P-82, manufactured by Showa Denko KK) in advance. : 1622-1411, 162-21401), manufactured by SIGMA-ALDRICH (trade names: P-4886, P-4761), manufactured by Meiji Food Materia Co., Ltd. (molecular weight: 880 k)).

Method of measuring weight average molecular weight of potassium salt of polyglutamic acid-2:
The weight average molecular weight measurement of the potassium salt of low molecular weight polyglutamic acid having a molecular weight of about 10 k was performed by gel filtration using a D-6000 (manufactured by Hitachi High-Technologies Corporation) HPLC system. The analysis conditions were as follows: TSKGel G3000PWXL gel filtration column (trade name, manufactured by Tosoh Corporation) was used as the analysis column, 0.1 M sodium sulfate was used as the eluent, the flow rate was 0.8 mL / min, the column temperature was 50 ° C., and UV detection was performed. The wavelength was 210 nm. The weight average molecular weight was determined using polyglutamic acid (Meiji Food Materia Co., molecular weight 9k), polyhydroxyproline (SIGMA-) whose weight average molecular weight was previously determined using pullulan (trade name: Shodex STANDARD P-82, manufactured by Showa Denko KK). Measurement was performed using ALDRICH, molecular weight 4k) as a standard product.

Metal analysis of polyglutamate:
Metal analysis of polyglutamate was performed by ion chromatography using a D-7000 (manufactured by Hitachi High-Technologies Corporation) HPLC system. Analytical conditions used were Shodex IC YK-G for the guard column, Shodex IC YK-421 (both trade names, manufactured by Showa Denko KK) for the analytical column, an eluent of 1.5 mM citric acid aqueous solution, and a flow rate of 1.0 mL. Detection was performed using an electric conductivity detector at a column temperature of 40 ° C./min. Using a sodium standard solution (1000 ppm) and a potassium standard solution (1000 ppm) manufactured by Kanto Chemical Co., Ltd. as standard samples, a calibration curve is prepared in the range of 10 to 100 mg / L for these standard products, and a polybasic curve is prepared based on these calibration curves. Metal analysis of glutamate was performed.

[Preparation Example 1] Preparation of polyglutamic acid potassium salt having a weight average molecular weight of 12,000 A 10% (w / w) aqueous solution of polyglutamic acid sodium salt having a weight average molecular weight of 9,000 (manufactured by Meiji Food Materia Co., Ltd.) Was adjusted to pH 2 or lower using hydrochloric acid under ice-cooling. Subsequently, the generated acid precipitate was recovered by centrifugation at 8,000 rpm for 5 minutes (trade name: himacCR21GIII, manufactured by Hitachi Koki Co., Ltd.), and the resulting precipitate was washed with the same amount of distilled water. And again subjected to centrifugation. After repeating this washing operation twice, the obtained precipitate was suspended in 300 mL of distilled water, and neutralized with an aqueous potassium hydroxide solution so that the pH was 7 or more. This acid treatment and neutralization treatment with potassium hydroxide were performed again, 2.5 times the amount of ethanol was added to the obtained neutralized sample, and the mixture was allowed to stand overnight under ice cooling. The precipitate produced by the addition of ethanol was collected by centrifugation at 14,000 rpm for 5 minutes (same as above), and the collected sample was dried under reduced pressure to obtain 27.4 g of a solid. The weight average molecular weight of this sample was calculated to be 12,000 by the aforementioned analysis method. In addition, in this sample, an amount of potassium corresponding to the amount of carboxyl groups of polyglutamic acid was detected, and sodium was below the detection limit. Therefore, substantially all the hydrogen atoms of the carboxyl groups of polyglutamic acid before neutralization were converted to potassium. It was confirmed that it was replaced.

[Preparation Example 2] Preparation of potassium salt of polyglutamic acid having a weight average molecular weight of 240,000 5% (w / w) of sodium salt of polyglutamic acid having a weight average molecular weight of 350,000 (manufactured by Meiji Food Materia Co., Ltd.) 1 L of an aqueous solution was prepared and adjusted to pH 1 or lower using hydrochloric acid under ice cooling. Subsequently, the generated acid precipitate was recovered by centrifugation at 8,000 rpm for 5 minutes (trade name: himacCR21GIII, manufactured by Hitachi Koki Co., Ltd.), and the resulting precipitate was washed with the same amount of distilled water. And again subjected to centrifugation. After this washing operation was repeated twice, the resulting precipitate was suspended in 800 mL of distilled water and neutralized with an aqueous potassium hydroxide solution so that the pH was 7 or more. This acid treatment and neutralization treatment with potassium hydroxide are performed again, and the precipitate formed by the addition of ethanol is collected by centrifugation at 14,000 rpm for 5 minutes (same as above), and the collected sample is subjected to vacuum drying. As a result, 36.2 g of a solid substance was obtained. The weight average molecular weight of this sample was calculated to be 240,000 by the above analysis method. In addition, in this sample, an amount of potassium corresponding to the amount of carboxyl groups of polyglutamic acid was detected, and sodium was below the detection limit. Therefore, substantially all the hydrogen atoms of the carboxyl groups of polyglutamic acid before neutralization were converted to potassium. It was confirmed that it was replaced.

[Preparation Example 3] Preparation of potassium salt of polyglutamic acid having a weight average molecular weight of 6,000 20% (w / w) of sodium salt of polyglutamic acid having a weight average molecular weight of 9,000 (manufactured by Meiji Food Materia Co., Ltd.) 125 mL of an aqueous solution was prepared and adjusted to pH 1 or lower using hydrochloric acid. Subsequently, the PGA solution was incubated at 95 ° C. for 12 hours, and the resulting acid precipitate was recovered by centrifugation at 8,000 rpm for 5 minutes (trade name: himacCR21GIII, manufactured by Hitachi Koki Co., Ltd.). The resulting precipitate was washed with the same amount of distilled water and again subjected to centrifugation. After repeating this washing operation twice, the obtained precipitate was suspended in 300 mL of distilled water, and neutralized with an aqueous potassium hydroxide solution so that the pH was 7 or more. This acid treatment and neutralization treatment with potassium hydroxide were performed again, 2.5 times the amount of ethanol was added to the obtained neutralized sample, and the mixture was allowed to stand overnight under ice cooling. The precipitate produced by the addition of ethanol was collected by centrifugation at 14,000 rpm for 5 minutes (same as above), and the collected sample was dried under reduced pressure to obtain 16.5 g of a solid. The weight average molecular weight of this sample was calculated to be 6,000 by the above analysis method.

[Test Example 1] Polyglutamic acid potassium salt suppresses increase in blood insulin concentration Polyglutamic acid potassium salt having a weight average molecular weight of 12,000 and 240,000 (prepared in Preparation Examples 1 and 2, respectively) and a weight average molecular weight of 9 , And 350,000 polyglutamic acid sodium salts (Meiji Food Materia Co., Ltd.) were used to prepare samples for oral administration as follows.
In addition, an oral administration test was performed as follows using 10-week-old male mice (C57BL / 6J Jcl: manufactured by CLEA Japan, Inc.) of 10 mice per group.

[Test Example 2] Blood GIP concentration increase inhibitory action of potassium salt of low molecular weight polyglutamic acid Potassium salt of polyglutamic acid having a weight average molecular weight of 6,000 (prepared in Preparation Example 3) and poly having a weight average molecular weight of 12,000 A sample for oral administration was prepared as follows using a potassium salt of glutamic acid (prepared in Preparation Example 1) and a sodium salt of polyglutamic acid having a weight average molecular weight of 9,000 (manufactured by Meiji Food Materia Co., Ltd.).
In addition, an oral administration test was carried out as follows using seven 8-week-old male mice (C57BL / 6J Jcl: manufactured by Clea Japan) in each group.

Preparation of orally administered samples:
Glucose (manufactured by Kanto Chemical Co., Inc.) and triolein (Glyceryl trioleate: manufactured by Sigma) are emulsified using lecithin (manufactured by egg, manufactured by Wako Pure Chemical Industries, Ltd.) and albumin (derived from bovine serum, manufactured by Sigma) to prepare an emulsion. did. A polyglutamate sample was added to this emulsion, and the final concentrations were 5 (w / w)% polyglutamate sample, 5 (w / w) glucose, 5 (w / w) triolein, emulsifier (lecithin 0). .2 (w / w)%, albumin 1.0 (w / w)%), orally administered samples were prepared. In addition, the sample which added water instead of the polyglutamate as a control sample was prepared.

Oral administration test:
Mice fasted overnight were subjected to initial blood collection using an heparinized hematocrit capillary tube (VITREX) from the orbital vein under ether anesthesia. Thereafter, the orally administered sample was orally administered with an oral sonde needle, and blood was collected from the orbital vein under ether anesthesia after 10 minutes, 30 minutes, 1 hour and 2 hours. The oral dose for mice is shown in Table 1 below.

Blood collected with a heparinized hematocrit capillary was stored under ice cooling until plasma separation, and then centrifuged at 11000 rpm for 5 minutes to obtain plasma. From the obtained plasma, the blood insulin concentration was measured using an insulin measurement kit (manufactured by Morinaga Biochemical Laboratory, ELISA method).
As a result of measuring the blood insulin concentration up to 2 hours after oral administration of the sample, it was found that the blood insulin concentration reached the maximum 10 minutes after the administration. Therefore, the difference (Δ value) between the maximum value of blood insulin concentration (10 minutes after administration) and the initial value (at the time of initial blood collection) is defined as the increase in maximum insulin concentration, and the values when the control group is 100 are shown in the following table. 2 (results of Test Example 1) and Table 3 (results of Test Example 2).

  Based on the value of the maximum increase in insulin concentration obtained, the statistically significant difference between groups was also examined. The results are also shown in Table 2. When significance (P <0.05) was recognized by analysis of variance, multiple control test (Bonferroni / Dunn method) was performed between the control group and each polyglutamate administration group, and a sodium salt administration group of similar molecular weight. And the potassium salt-administered group were tested, and the significance was judged from the obtained results with P <0.05 as a significant difference.

From the results shown in Table 2, it was found that the sodium salt of polyglutamic acid does not have a significant inhibitory effect on the increase in blood insulin concentration. At the same time, polyglutamic acid sodium salt was found not to be significantly different from the control group, but the effect of suppressing an increase in blood insulin concentration was enhanced when the molecular weight was larger. On the other hand, polyglutamic acid potassium salt showed an inhibitory effect on the increase in blood insulin concentration regardless of the molecular weight.
In particular, the polyglutamic acid potassium salt having a weight average molecular weight of 12,000 had a remarkably excellent effect of suppressing the increase in the maximum blood insulin concentration by 50% or more (up to about 45% in the control ratio).

The sodium salt of polyglutamic acid was not effective in suppressing the increase in blood insulin concentration when the weight average molecular weight was about 9,000, whereas the potassium salt of polyglutamic acid having a weight average molecular weight of 12,000. It was found that the maximum blood insulin concentration was markedly suppressed.
Furthermore, it has also been clarified that the polyglutamic acid potassium salt having a low molecular weight and a weight average molecular weight of 6,000 has the same effect of suppressing the increase in insulin concentration as the potassium salt of polyglutamic acid having a weight average molecular weight of 12,000.

  From the results of Test Examples 1 and 2, the sodium salt of polyglutamic acid tends to increase the action of suppressing the increase in blood insulin concentration when the molecular weight is larger, whereas the potassium salt of polyglutamic acid is unexpectedly low. It was also found that the effect of suppressing the increase in blood insulin concentration is further enhanced by the molecule. Since the lower the molecular weight, the lower the viscosity of polyglutamate, the easier the handling in the manufacturing process will be if a low molecular weight potassium salt of polyglutamic acid can be used. Moreover, when the blood insulin level increase inhibitor of the present invention is in the form of an oral liquid, a low-molecular potassium salt of polyglutamic acid is used, so that the throat, mucus, and swallowing during drinking can be used. There is also an advantage that the liquid agent can be made excellent in ease of use.

  As described above, it is known that an excessive increase in insulin concentration causes insulin resistance, and thus obesity and diabetes. Therefore, the potassium salt of polyglutamic acid can be suitably used for the prevention and improvement of obesity and diabetes by effectively suppressing the secretion of insulin after meal.

Claims (2)

  A blood insulin level increase inhibitor comprising a potassium salt of polyglutamic acid as an active ingredient.   A blood insulin level increase inhibitor comprising a potassium salt of polyglutamic acid.