JP2008169129A - Liver function improving agent containing water-soluble potato peptide - Google Patents

Abstract

The present invention provides a liver function improving agent excellent in safety and liver function improving function.
A liver function improving agent comprising a water-soluble potato peptide.
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Description

  The present invention relates to the use of a water-soluble potato peptide as a liver function improving agent.

  Several drugs such as glycyrrhizin and traditional Chinese medicines such as Sho-saiko-to are used as therapeutic agents for liver diseases, but there are few choices and development of new therapeutic agents for liver diseases is desired. Similarly, several types of foods such as turmeric are used as functional foods for the purpose of prevention and improvement of liver dysfunction, but there are few choices, and functional foods with new liver dysfunction prevention and improvement actions. Development is desired.

  At the present time, there are no foods for specified health use or functional nutritional foods whose health claims claim to prevent or improve liver dysfunction. Therefore, development of foods for preventing and improving liver dysfunction with high safety and reliability Is strongly desired.

Soy protein has long been known to have a lipid metabolism-regulating action that lowers blood cholesterol and triglyceride levels. It is also known that a potato-derived peptide mixture (potato peptide) has angiotensin converting enzyme inhibitory activity (Patent Document 1). Furthermore, it is also known that potato peptides have an action to prevent or ameliorate lifestyle-related diseases caused by inappropriate eating habits or lack of exercise (Japanese Patent Application No. 2006-125677). However, another physiological function of the potato peptide was not known.
JP 2000-4799 A

  To provide a liver function improving agent excellent in safety and liver function improving function.

  As a result of diligent efforts to solve the above problems, the present inventors have found that a water-soluble potato peptide has an action of suppressing liver dysfunction and completed the present invention. That is, the present invention relates to a liver function improving agent containing a water-soluble potato peptide.

  The water-soluble potato peptide of the present invention can be obtained by digesting a potato-derived protein with a proteolytic enzyme. The molecular weight of the water-soluble potato peptide of the present invention is a maximum of 10 kDa.

  As the potato protein that is a raw material for producing the water-soluble potato peptide of the present invention, any conventionally known potato protein can be used, such as a potato protein produced as a by-product during the production of potato starch.

  The water-soluble potato peptide of the present invention can be obtained by treating potato protein with a proteolytic enzyme. As the proteolytic enzyme, any conventionally known proteolytic enzyme can be used. Preferably, “Alcalase 2.4L” (registered trademark) or “Flavorzyme” (registered trademark) (Novo Nordisk Industries) is used. be able to.

  In the production of a water-soluble peptide using potato protein as a raw material in the present invention, first, an alkaline agent, preferably sodium hydroxide is added to a 5 to 15% by weight aqueous suspension of potato protein to adjust the pH to 6.0. It is adjusted to ˜12.0, preferably 7.5 to 8.0.

  Heating to 80-90 ° C. after adjusting the pH is desirable from the viewpoint of preventing contamination with bacteria and promoting enzyme reaction by denaturation of the potato peptide.

  “Alcalase 2.4L” (registered trademark) is allowed to act at 40 to 60 ° C., preferably 50 to 55 ° C. When the pH drops to around 7, “Flavorzyme” (registered trademark) is added to allow these enzymes to act continuously.

  When an aqueous suspension of 10% by weight potato peptide adjusted to pH 7.5 to 8.0 by adding alkali is subjected to an enzyme treatment, the solution is first heated to 80 to 90 ° C. and then cooled to 50 ° C. 2.4L "is added at least 10 anson units per kg of potato protein and reacted at 50 ° C for 1-5 hours to lower the pH to around 7, followed by" flavorzyme L "at 1500u / kg potato protein. The water-soluble potato peptide of the present invention can be obtained by adding the above and further reacting at 50 ° C. for 15 hours or longer.

  The reaction solution after the enzyme treatment is heated to 80 ° C. or more to inactivate the enzyme in the reaction solution, and then the insoluble matter in the reaction solution is removed by filtration. The resulting filtrate contains potato-specific polyphenols mixed in the potato peptide, so the filtrate has a greenish dark color and cannot be preferably applied to various uses in terms of appearance. Further purification is desirable. In many cases, the mixed polyphenols are colored by reacting with trace metals, particularly iron, and adsorption and decolorization with activated carbon has little effect.

  Therefore, when an ion exchange resin is used, a greenish dark color is removed and a light brown liquid is obtained. When a small amount of activated carbon is added to the liquid and filtered, the liquid can be purified almost colorless.

  By spray-drying the purified solution thus obtained, the water-soluble potato peptide of the present invention in the form of white to light yellow powder can be obtained in high yield. The molecular weight distribution of the obtained water-soluble potato peptide is about 20-30% for peptides with a molecular weight of 100-500 and about 70-80% for peptides with a molecular weight of 500-3000. Moreover, a desired fraction can be obtained by fractionating the water-soluble potato peptide with a gel filtration agent.

  The liver function-improving agent of the present invention can be formulated using a water-soluble potato peptide produced by the above method in combination with a known non-toxic pharmaceutical carrier in accordance with a conventional method. The liver function-improving agent of the present invention can be administered in various dosage forms. For example, oral administration agents include solid agents such as tablets, granules, powders, capsules, and soft capsules, solutions, and suspensions. Liquids such as suppositories and emulsions, lyophilized preparations, and the like, and parenteral administration agents include suppositories, sprays, transdermal absorption agents, etc., in addition to injections. It can be prepared by means. Examples of the non-toxic pharmaceutical carrier include glucose, lactose, sucrose, starch, mannitol, dextrin, fatty acid glyceride, polyethylene glycol, hydroxyethyl starch, ethylene glycol, polyoxyethylene sorbitan fatty acid ester, amino acid, albumin, water And physiological saline. If necessary, conventional additives such as stabilizers, lubricants, wetting agents, emulsifiers, binders and the like can be appropriately added. In the liver function improving agent according to the present invention, the dosage of the water-soluble potato peptide is appropriately selected and determined according to the patient's age, weight, symptom, degree of disease, administration schedule, formulation form, etc. The daily dose is about 0.01 to 10 g / kg body weight, and the dose may be divided into several times a day.

  The water-soluble potato peptide of the present invention is considered to be highly safe because it is a natural ingredient, and can also be taken as a functional food for preventing or improving liver dysfunction. The functional food characterized by containing the water-soluble potato peptide of the present invention can be positioned as a food for specified health use, a nutritional functional food, or a health food.

  The functional food of the present invention only needs to contain the potato peptide according to the present invention. Therefore, it may be a food consisting only of the potato peptide or a food containing components other than the potato peptide. Components other than the potato peptide of the present invention are not particularly limited as long as they do not inhibit the liver function improving action. Specific examples include potato components other than the potato peptide, plant and animal proteins, carbohydrates, dietary fiber, lipids, various vitamins, minerals, and the like. The shape of the food is not particularly limited, and may be various shapes such as a solid, liquid, powder, and paste.

  Since the functional food material of the present invention contains the potato peptide, the functional food material has a liver function improving effect.

  Specific examples of the food according to the present invention include tablets, granules, powders, drinks and the like containing the food material according to the present invention as so-called nutritional supplements (supplements). In addition, the seasoning containing the said foodstuff material, confectionery, bread | pan, side dish, drinking water etc. can be mentioned.

  Needless to say, the food materials, foods, and pharmaceuticals according to the present invention are intended for humans, but are not limited to humans and can be used for a wide range of animals. In particular, pets such as dogs and cats suffering from liver dysfunction are suitable as subjects.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples.

Example 1 (Production of potato peptide)
4500 L of water and 2 kg of sodium hydroxide were added to 450 kg of potato protein, and suspended by stirring at 50 ° C. for 10 minutes. This suspension was allowed to stand for 10 minutes, about 3000 L of the supernatant was discarded, about 3000 L of water was newly added, and the suspension was suspended by stirring at 50 ° C. for 10 minutes, and this suspension was left for 10 minutes. This suspension was left for 10 minutes, about 3000 L of the supernatant was discarded, and about 3000 L of water was newly added. The suspension was sterilized by heating it at 90-95 ° C. for 15 minutes. Then, 2000 L of water was added.

  When 3 g of “Alcalase 2.4 L” was added thereto and reacted at 50 to 52 ° C. for 4 hours with stirring, the pH of the reaction solution was 6.9. To this reaction solution, 0.75 g of “flavorzyme 1000 L”) was added and reacted at 50 to 52 ° C. for 16 hours with stirring. After completion of the reaction, the mixture was heated to 90-95 ° C. and held for 15 minutes to deactivate the enzyme, and allowed to cool for 18 hours. The reaction solution after standing to cool had a supernatant portion of about 1/3, the remainder was a light colloid-like insoluble matter, and its pH was 6.8.

  105 kg of diatomaceous earth as a filter aid was added to the reaction solution after being allowed to cool and stirred for 15 minutes, followed by suction filtration. The residue was washed with water to obtain 700 ml of a dark grayish brown filtrate. While stirring the filtrate, 1.2 ml of acetic acid was added to adjust the pH to 5.5, 20 g of activated carbon was added and stirred for 15 minutes, followed by suction filtration. The residue was washed with water to obtain 740 ml of filtrate. What turned out gradually turned dark gray and slightly cloudy. The filtrate was concentrated under reduced pressure to 200 ml and then freeze-dried to obtain 113 kg of a gray dry product. This dried product had a water content of 0.83% by weight, an ignition residue of 4.3% by weight, and total nitrogen of 12.3% by weight.

Example 2 (Influence on rats)
Influence on liver function First, the influence on GOT and GPT in rat serum was examined. A commercial feed intake group was used as a control group. The treatment group comprises four groups of casein (CAS), high amylose corn starch (HAS), PPI (potato peptide) and PPI / HS (mixture of PPI and HAS), and D-galactosamine at a dose of 300 mg / kg intraperitoneally. Administration to induce liver damage. Blood was collected 20 hours after administration of D-galactosamine, and serum GOT and GPT were measured. The results are shown in FIG. In the potato peptide intake group, serum GOT and GPT values were significantly reduced, and it was proved that the potato peptide had an effect of improving liver dysfunction.

  Subsequently, in order to elucidate the mechanism of the liver function improving action by the potato peptide, the glutathione enzyme activity in the liver was measured.

  Animals used: Six-week-old SD male rats were purchased from Charles River Japan Co., Ltd. The breeding conditions were room temperature 23 ± 1 ° C., humidity 60 ± 5%, and light / dark cycle 12 hours (light 07:00, dark 19:00). Rats were individually housed in plastic cages. Rats were bred according to the Guide of the Care and Use of Laboratory Animals. The number of rats per group was 6.

  After taking a normal meal for 7 days, a test meal was taken for 10 days, and after 2 days, the rats were dissected and the liver was removed. In the liver injury model, D-galactosamine was intraperitoneally administered at a dose of 300 mg / kg, and blood was collected and dissected after 20 hours.

Potato peptide (PPI) feed composition (g / kg diet)
Potato peptide 250
Cornstarch 655
Corn oil 50
Minerals (AIN-76) 35
Vitamins (AIN-76) 10
In casein feed, the same amount of casein is blended instead of potato peptide, and in soy protein feed (SPI), the same amount of soy protein is blended instead of potato peptide, and rice protein feed (E-RPI) Then, the same amount of rice protein was blended in place of the potato peptide. The apparent digestibility was 95 for Casein, 93 for SPI, 90 for PPI, and 94 for E-RPI.

The body weight (g), body weight change (g / 15 days), test food intake (g / 15 days) and feed efficiency at the end of the test period were shown. The symbol on the right side of the numerical value indicates that there is a significant difference (p <0.05) when analyzed by analysis of variance and Duncan's multiple range test.
Group Casein SPI PPI E-RPI Weight 312bc 303ab 284ab 297ab 326c
Weight change 94.1b 85.0b 67.7ab 80.1ab 110.8c
Intake 277b 277b 247b 282b 329c
Feed efficiency 0.33b 0.30ab 0.27a 0.28a 0.33b

  Body weight after the end of the test meal was lower in rats that received PPI. Therefore, the intake of PPI was less than that of other foods.

The liver weight (g) and liver weight per body weight (liver g / 100 g body weight) after completion of the test were shown. The symbol on the right side of the numerical value indicates that there is a significant difference (p <0.05) when analyzed by analysis of variance and Duncan's multiple range test.
Group Casein SPI PPI E-RPI Liver weight 14.9b 12.6a 12.6a 12.5a 15.3b
/ Weight 4.67b 4.16a 4.44a 4.21ab 4.69b

  The weight of the dissected liver after the end of the test showed less values for soy protein, rice protein and potato peptide compared to commercial food casein.

Reduced glutathione (GSH) content (mg / g liver) and metallothionein (MT) content (μmol / min · mg protein) and glutathione S transferase (GST) activity (nmol NADPH oxidation / min mg protein) and glutathione peroxidase (GPX) activity (μg / g liver). The symbol on the right side of the numerical value indicates that there is a significant difference (p <0.05) when analyzed by analysis of variance and Duncan's multiple range test.
Group Casein SPI PPI E-RPI Commercial GSH 1.39b 1.12a 1.35b 1.39b 1.44b
GST 1.78a 1.86ab 2.49c 1.76ab 2.13b
GPX 704 559 576 667 759
MT 43.0 58.0 52.6 72.3 44.4

  The glutathione S transferase (GST) activity contained in the liver was significantly higher in the potato peptide intake group than in the other four test meals.

  Furthermore, when mRNA was extracted from the liver and the gene expression level was analyzed using a DNA microarray, three gene expression levels of glutathione S-transferase μ type 3, glutathione S-transferase π2, and glutathione peroxidase 3 were detected in the potato peptide intake group. However, it became clear that it increased exceeding 1.5 times.

  From the above data, it was proved that the potato peptide had an effect of increasing the activity of glutathione S transferase in the liver.

  In recent years, various compounds such as drugs and food additives have increased and accumulated in the environment, and mammals including humans have been exposed to these. When these compounds are recognized as xenobiotics, they are detoxified and metabolized mainly in the liver. In this detoxification metabolism, the first phase which mainly enhances the water solubility of xenobiotics mainly by hydroxylation catalyzed by a group of enzymes called cytochrome P450, the metabolites of the first phase and other xenobiotics as glutathione etc. There is a second phase that can be conjugated or methylated to convert it into a more water-soluble metabolite to facilitate its elimination from the body. Glutathione S transferase is known as an enzyme involved in the second phase detoxification metabolic system.

  Therefore, it can be said that glutathione S-transferase has an important defense mechanism against xenobiotics and thus a mechanism against carcinogenesis, and the liver function improving agent of the present invention increases glutathione S-transferase or enhances its activity in vivo. Thus, improvement of the biological defense function and removal of DNA damage caused by xenobiotics are also expected.

  The liver function improving agent of the present invention is useful for improving liver function.

Effects on rat serum GOT and GPT

Claims (1)

  A liver function improving agent comprising a water-soluble potato peptide.

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