JP5844527B2 - Blood GIP level increase inhibitor - Google Patents

Description

  The present invention relates to a blood GIP concentration increase inhibitor.

GIP (Gastric inhibitory polypeptide or glucose-dependent insulinotrophic polypeptide) is one of the gastrointestinal hormones and is secreted from K cells present in the small intestine when fed. GIP is known to have a gastric acid secretion inhibitory action and a gastric movement inhibitory action (see Non-Patent Documents 1 to 3).
In addition, GIP is known to promote insulin secretion from pancreatic β cells and enhance glucose uptake into adipocytes in the presence of insulin. Therefore, it is considered that the action of GIP is a factor in obesity. In fact, there is a report that obesity is suppressed when the function of GIP is inhibited (see Non-Patent Document 4).
Furthermore, it has been reported that GIP contributes to insulin resistance (see Non-Patent Document 4). When insulin resistance develops, the absorption of sugar by insulin decreases, resulting in hyperinsulinemia. Hyperinsulinemia is said to be the root cause leading to the development of various lifestyle-related diseases such as obesity, and prevention and improvement of insulin resistance is also from the aspect of reducing the risk of lifestyle-related diseases. is important.

Thus, if GIP can be effectively suppressed, effects such as digestion promotion, improvement of stomach upset, prevention / improvement of obesity and insulin resistance can be expected.
Based on previous studies, 3-bromo-5-methyl-2-phenylpyrazolo [1,5-a] pyrimidin-7-ol (BMPP) and pyrazolopyrimidine compounds are known as substances that inhibit the function of GIP. It has been. Moreover, guar gum etc. are known as what suppresses secretion of GIP after a meal (refer patent documents 1 and 2, nonpatent literatures 5-10). However, these substances are not sufficient in terms of safety and effectiveness.

  On the other hand, polyglutamic acid is widely used in the fields of food, medicine, cosmetics and the like as a moisturizing agent and absorbent because of its high water-holding power, and has attracted attention as a highly safe biodegradable polymer. In addition, it has been reported that polyglutamic acid has an effect of promoting calcium absorption from the small intestine and an effect of suppressing an increase in blood pressure (see, for example, Patent Documents 3 and 4). Moreover, in order to suppress an increase in blood sugar level, a blood sugar level improving agent using polyglutamic acid has been proposed (see Patent Document 5). Furthermore, it has been reported that polyglutamic acid has an effect of suppressing the absorption of neutral lipids and can be used for the treatment, improvement, and suppression of onset of hypertriglyceridemia (see Patent Document 6).

  However, there has been no report on the inhibitory action on the increase in blood GIP concentration related to a specific salt of polyglutamic acid.

International Publication No. 01/87341 Pamphlet JP 2006-213598 Gazette Japanese Patent Laid-Open No. 5-95767 JP 2008-255063 A JP 2005-200330 A JP 2009-173634 A

J. C. Brown et al., Canadian J Physiol Pharmacol 47: 113-114, 1969 J. M. Falko et al. Clin Endocrinol Metab 41 (2): 260-265, 1975 Toshiji Oda et al., Gastrointestinal function and pathology, 1981, Chugai Medical, P205-216 Miyawaki K et al., Nat Med. 8 (7): 738-42, 2002 Gagenby S J et al., Diabet Med. 13 (4): 358-64, 1996 Ellis PR et al., Br J Nutr. 74 (4): 539-56, 1995 Simoes Nunes C et al., Reprod Nutr Dev. 32 (1): 11-20, 1992 Morgan LM et al., Br J Nutr. 64 (1): 103-10, 1990 Requejo F et al., Diabet Med. 7 (6): 515-20, 1990 Morgan et al., Br J Nutr. 53 (3): 467-75, 1985

  An object of the present invention is to provide a blood GIP concentration increase inhibitor useful for pharmaceutical or food applications. Specifically, the present invention relates to reduction, prevention, improvement, alleviation, treatment, promotion of digestion, or development of obesity or insulin resistance caused by an increase in blood GIP concentration after meals. It is an object of the present invention to provide a blood GIP concentration increase inhibitor useful as a food or non-pharmaceutical use for risk reduction, prevention, improvement, mitigation, or treatment.

  The present inventors examined the GIP secretion inhibitory action of polyglutamic acid and its salts, and the potassium salt of polyglutamic acid significantly suppressed postprandial GIP secretion, promoted digestion, improved stomach sag, or obesity and insulin resistance. It was found to be particularly useful for the prevention and improvement of sex. The present invention has been completed based on this finding.

  The present invention relates to a blood GIP concentration increase inhibitor containing a potassium salt of polyglutamic acid as an active ingredient.

  According to the blood GIP concentration increase inhibitor of the present invention, an increase in blood GIP concentration, particularly an increase in blood GIP concentration after a meal can be suppressed. Further, the blood GIP concentration increase inhibitor of the present invention effectively suppresses the increase in blood GIP concentration, thereby reducing, preventing, improving, mitigating, treating, promoting digestion, It is useful for reducing, preventing, improving, mitigating and treating the risk of developing obesity and insulin resistance.

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 effect of significantly suppressing an increase in blood GIP concentration as compared with polyglutamic acid and other polyglutamic acid salts. Therefore, the potassium salt of polyglutamic acid can be used as a GIP concentration increase inhibitor in blood and can be used to produce the GIP increase inhibitor. Until now, it has not been known that the potassium salt of polyglutamic acid has an action of suppressing an increase in blood GIP concentration. In addition, it is not known that the potassium salt of polyglutamic acid has an effect of preventing or improving obesity or insulin resistance.

The blood GIP concentration increase inhibitor of the present invention can be suitably used particularly for suppressing an increase in blood GIP concentration after a meal. Specifically, it is preferably used for suppressing an increase in blood GIP concentration after ingesting a diet containing both lipid and carbohydrate, particularly a diet rich in lipids, especially a diet rich in triacylglycerol. Can do.
The triacylglycerol contained in the meal is not particularly limited, and specific examples of the lipid component rich in triacylglycerol include butter, lard, fish oil, corn oil, rapeseed oil, olive oil, sesame oil and the like.
There are no particular restrictions on the carbohydrate components contained in the meal, and specific examples include cooked rice, starch, wheat flour, sugar, fructose, glucose, glycogen and the like.
In addition, the intake amount of the lipid and carbohydrate is not particularly limited as long as it is within the range included in a normal meal.
In the present invention, “inhibition of increase in blood GIP concentration” mainly means suppression of increase in blood GIP concentration that occurs after meals. The suppression of the increase in blood GIP concentration after a meal does not necessarily mean that the increase in blood GIP concentration caused after a meal is completely suppressed, but the blood GIP 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 GIP concentration compared to the case where there is no blood GIP. And the “blood GIP concentration increase inhibitory action” in the present invention is a GIP secretion inhibitory action that suppresses the increase in blood GIP concentration by suppressing GIP secretion from the gastrointestinal tract, and a decrease in blood GIP concentration. It is a concept that includes any GIP lowering action that suppresses an increase in blood GIP concentration.

As shown in the examples described below, the remarkable inhibitory effect on the increase in blood GIP concentration of the polyglutamic acid potassium salt of the present invention was generally observed regardless of the molecular weight of the polyglutamic acid potassium salt. The higher the molecular weight of the potassium salt is, the better the GIP concentration increase suppressing effect is.
Therefore, in order to more effectively suppress the increase in blood GIP concentration, the 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. More preferably, it is more preferably 2,000 or more, further preferably 3,000 or more, and particularly preferably 5,000 or more.
The upper limit of the weight average molecular weight of the potassium salt of polyglutamic acid used is preferably about 5,000,000. However, when the production inhibitor and the blood insulin level increase inhibitor of the present invention is used as an oral liquid preparation, From the standpoints of throat soaking, sliminess, ease of swallowing, etc., it is preferable that the viscosity is relatively low, and the weight average molecular weight of the potassium salt of polyglutamic acid used is 1,000,000 or less Is more preferably 500,000 or less.
More specifically, the weight average molecular weight of the potassium salt of polyglutamic acid used in the present invention is preferably 500 to 5,000,000, more preferably 1,000 to 1,000,000. More preferably from 3,000 to 500,000, further preferably from 3,000 to 500,000, particularly preferably from 4,000 to 400,000, and from 5,000 to 300,000. It is particularly preferable. 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 GIP secretion after ingesting carbohydrates, lipids and / or proteins, thereby suppressing an increase in blood GIP concentration. And the inhibitory effect is remarkably excellent compared with polyglutamic acid and other polyglutamate.

  The blood GIP concentration increase inhibitor of the present invention may be the potassium salt of polyglutamic acid itself. In addition, the blood GIP concentration increase inhibitor of the present invention is a suitable 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. The content of the potassium salt of polyglutamic acid in the blood GIP concentration increase inhibitor of the present invention is not particularly limited, but is preferably 0.01 to 100% by mass, and preferably 0.1 to 95% by mass. More preferably, it is contained in an amount of 1 to 90% by mass, more preferably 5 to 85% by mass.

  When the blood GIP concentration increase inhibitor of the present invention is used for foods, pharmaceuticals, and the like, the potassium salt of polyglutamic acid alone is administered to humans and animals in the digestive tract, intraperitoneal, intravascular, intradermal, In addition to administration by subcutaneous administration or the like, it can be ingested as an active ingredient in various foods, pharmaceuticals, pet foods and the like. The concept of food is general food, as well as reduction, prevention, improvement, alleviation and treatment of stomach upset risk, promotion of digestion, and reduction, prevention, improvement, alleviation and treatment of obesity and insulin resistance. If necessary, it can be applied to foods such as beauty foods, foods for the sick, 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.

  When preparing an oral solid preparation, an excipient, a binder, a disintegrant, a lubricant, a coloring agent, a corrigent, a corrigent and the like were added to the potassium salt of polyglutamic acid as necessary. Thereafter, 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 foods and preparations is preferably 0.001 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 GIP concentration increase inhibitor of the present invention can be used before, during or after a meal, but is preferably used before or during a meal, and more preferably from 1 hour before the meal.
The subject of administration or ingestion is not particularly limited as long as it is a person who needs it, but fasting blood glucose level is 100 mg / dL or more, fasting blood triglyceride value is 100 mg / dL or more, and / or fasting. Those whose blood GIP value is 10 pg / mL or more are preferred. In addition, obese and metabolic syndrome patients and their preparatory groups are also preferable as administration or ingestion subjects. As a standard for obesity, in Japan, the standard BMI is set to 22. Therefore, a person with BMI = 22 or more is preferable, and a person with BMI = 25 or more is more preferable. On the other hand, in Europe and the United States, as a standard of obesity, BMI of 25 or more is overweight, so those with BMI = 25 or more are preferable, and those with BMI = 30 or more are more preferable. According to the diagnostic criteria of metabolic syndrome, in the case of Japanese, the waist is 85 cm or more for men and 90 cm or more for women, and (1) blood triglyceride is 150 mg / dL or more or HDL cholesterol is 40 mg / A person who has one or more of the following three items: less than dL, (2) hyperglycemia (fasting blood glucose is 110 mg / dL or more), and (3) hypertension (130/85 mHg or more) Since those who are in the reserve group and who apply to two or more items are considered to fall under the metabolic syndrome, it is preferable that these persons be subjects for administration or ingestion. In the case of the United States, metabolic syndrome is considered to satisfy at least three of abdominal circumference (102 cm or more for men, 88 cm or more for women), high neutral fat, low HDL, high blood pressure, and high fasting blood glucose. From these, it is preferable that these persons, including those in the reserve group corresponding to two or more, be subjects for administration or ingestion.

  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 this sample, an amount of potassium corresponding to the amount of carboxyl groups in polyglutamic acid was detected, and sodium was below the detection limit. Therefore, substantially all of the hydrogen atoms of the carboxyl groups were replaced with potassium. Was confirmed.

[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 this sample, an amount of potassium corresponding to the amount of carboxyl groups in polyglutamic acid was detected, and sodium was below the detection limit. Therefore, substantially all of the hydrogen atoms of the carboxyl groups were replaced with potassium. Was confirmed.

[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 became 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] Inhibition of blood GIP concentration increase by potassium salt of polyglutamic acid Potassium salt of polyglutamic acid 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 GIP concentration was measured using a Rat / Mouse GIP (Total) ELISA kit (manufactured by Linco Research / Millipore co., ELISA method).
As a result of measuring the blood GIP concentration up to 2 hours after oral administration of the sample, it was found that the blood GIP concentration reached the maximum 10 minutes after the administration. Therefore, the difference (Δ value) between the maximum value of blood GIP concentration (10 minutes after administration) and the initial value (at the time of initial blood collection) is defined as the increase in maximum GIP 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 obtained maximum GIP concentration increase value, a statistically significant difference between groups was also examined, and 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 of Table 2, it was found that the increase in blood GIP concentration was not suppressed in the administration group of a relatively low molecular weight polyglutamic acid sodium salt having a weight average molecular weight of 9,000. On the other hand, by increasing the weight average molecular weight of polyglutamic acid sodium salt by 4 times to 350,000, it is possible to suppress an increase in blood GIP concentration by about 45% (up to about 55% in the control ratio) compared to the control group. However, when polyglutamic acid potassium salt is used, the increase in blood GIP concentration is almost 40% at a weight average molecular weight of about 1/6 (weight average molecular weight 12,000). Can be suppressed (up to about 60% by control ratio), and by increasing its weight average molecular weight to 240,000, the increase in blood GIP concentration can be suppressed by about 60% (up to about 40% by control ratio). I understood.

From the results in Table 3, it can be seen that the increase in blood GIP concentration is not suppressed in the administration group of a relatively low molecular weight polyglutamic acid sodium salt having a weight average molecular weight of 9,000. On the other hand, with the potassium salt of polyglutamic acid having a weight average molecular weight of 12,000, an increase in blood GIP concentration could be suppressed by about 50%, and the result of Test Example 1 was reproduced.
It has also been clarified that a polyglutamic acid potassium salt having a weight average molecular weight of 6,000, which has a lower molecular weight, has a GIP reducing effect equivalent to that of a potassium salt having a weight average molecular weight of 12,000 polyglutamic acid.

  From the results of Test Example 2, the salt of polyglutamic acid has an inhibitory effect on the increase in blood GIP concentration, and among them, the potassium salt of polyglutamic acid has a significantly excellent inhibitory effect on the increase in blood GIP concentration over a wide molecular weight range. I understood it.

  As described above, GIP is known to play a role in inhibiting gastric acid secretion and gastric motility, increasing glucose uptake into adipocytes in the presence of insulin, and inducing insulin resistance. Therefore, the potassium salt of polyglutamic acid should be suitably used for promoting digestion, preventing and improving stomach sag, and preventing and improving obesity and insulin resistance by effectively suppressing an increase in blood GIP concentration. it can.

Claims (2)

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