Agent for converting isoflavone glycosides to isoflavone aglycones, composition for converting isoflavone glycosides to isoflavone aglycones, method for converting isoflavone glycosides to isoflavone aglycones, and method using lactic acid bacteria identified by accession number NITE P-755.

Abstract

This invention provides an agent and composition having high aglyconization ability by containing lactic acid bacteria identified under accession number NITE P-755, as well as a method for efficiently converting isoflavone glycosides to isoflavone aglycones and a method for using lactic acid bacteria identified under accession number NITE P-755. [Solution] The agent for converting isoflavone glycosides to isoflavone aglycones contains lactic acid bacteria identified by accession number NITE P-755.

Description

Technical Field

[0001] The present invention relates to an agent for converting an isoflavone glycoside into an isoflavone aglycone, a composition for converting an isoflavone glycoside into an isoflavone aglycone, a method for converting an isoflavone glycoside into an isoflavone aglycone, and a method for using lactic acid bacteria identified by accession number NITE P-755.

Background Art

[0002] Isoflavones, which are abundantly contained in leguminous plants such as soybeans and kudzu, have estrogenic activity, and it is known that ingestion of isoflavones has a preventive effect against breast cancer, osteoporosis, hypercholesterolemia, menopause disorders, and the like. Therefore, isoflavones generally need to be efficiently ingested for maintaining women's health.

[0003] Isoflavones, for example in soybeans, mainly exist in the form of glycosides bound to sugars, but are metabolized and absorbed into aglycones in which the sugars are cleaved by intestinal bacteria (β-glucosidase-producing bacteria) in the body. Thus, since the conversion of isoflavone glycosides to aglycones depends on intestinal bacteria, there are generally individual differences. Even if soybeans are ingested to take in isoflavones, the actual rate of conversion to aglycones in the body is low, and the absorption of isoflavone aglycones in the body may not be good.

[0004] So far, several reports have been made on the ability of lactic acid bacteria to convert soy isoflavones into aglycones.

[0005] In Non-Patent Document 1, the ability of lactic acid bacteria isolated from various plant food materials to convert soy isoflavone glycosides into aglycones has been reported. In addition, in Non-Patent Document 2, the ability of lactic acid bacteria HOKKAIDO strain isolated from pickles to convert soy isoflavone glycosides into aglycones has been reported.

Prior Art Documents

Non-Patent Documents

[0006] [Non-Patent Document 1] Yaeko Ueno et al., Conversion ability of lactic acid bacteria isolated from plant-based food materials to soy isoflavone aglycone, Journal of the Japanese Society for Food Science and Technology, 58(4), pp. 173-177, 2011. [Non-Patent Document 2] Ryoji Nakagawa et al., Aglyconeization of soy milk isoflavones by Lactobacillus plantarum HOKKAIDO, Research Report of the Food Processing Research Center, Hokkaido Research Organization, No. 9, pp. 21-25, 2011. [Overview of the project] [Problems that the invention aims to solve]

[0007] It is clear that isoflavones generally need to be consumed efficiently to maintain women's health, and there has been a need for the development of agents and compositions that can efficiently convert isoflavone glycosides into aglycones.

[0008] The present invention has been made in view of the above circumstances, and aims to provide an agent and composition having high aglyconization ability by containing the lactic acid bacteria identified by accession number NITE P-755, as well as a method for efficiently converting isoflavone glycosides to isoflavone aglycones and a method for using the lactic acid bacteria identified by accession number NITE P-755. [Means for solving the problem]

[0009] To achieve the above objective, the agent for converting isoflavone glycosides to isoflavone aglycones according to the first aspect of the present invention is: It contains lactic acid bacteria identified by accession number NITE P-755.

[0010] A composition for converting isoflavone glycosides to isoflavone aglycones according to a second aspect of the present invention is: It contains lactic acid bacteria identified by accession number NITE P-755.

[0011] A method for converting an isoflavone glycoside to an isoflavone aglycone according to a third aspect of the present invention is: The process includes contacting an isoflavone glycoside with lactic acid bacteria identified by accession number NITE P-755.

[0012] A method using lactic acid bacteria identified by accession number NITE P-755, relating to the fourth aspect of the present invention, is: This is a method for converting isoflavone glycosides to isoflavone aglycones. [Effects of the Invention]

[0013] According to the present invention, by containing the lactic acid bacteria identified by accession number NITE P-755, it is possible to provide an agent and composition having high aglyconization ability, as well as a method for efficiently converting isoflavone glycosides to isoflavone aglycones and a method for using the lactic acid bacteria identified by accession number NITE P-755. [Brief explanation of the drawing]

[0014] [Figure 1] This graph shows the pH changes during soy milk fermentation by various lactic acid bacteria. [Figure 2] This graph shows the conversion ability of various lactic acid bacteria to isoflavone aglycones in soy milk. [Modes for carrying out the invention]

[0015] (1. An agent for converting isoflavone glycosides to isoflavone aglycones) The agent for converting isoflavone glycosides to isoflavone aglycones according to the present invention contains lactic acid bacteria identified under accession number NITE P-755.

[0016] The agent of the present invention contains lactic acid bacteria (KB1) identified by deposit number NITE P-755, and can convert isoflavone glycosides into isoflavone aglycones with high efficiency. The inventors of the present invention newly found that among lactic acid bacteria, KB1 particularly has a remarkably excellent ability to convert isoflavone glycosides into isoflavone aglycones, leading to the present invention. Isoflavone glycosides are converted into isoflavone aglycones and absorbed in the intestine. For example, by ingesting the agent of the present invention and isoflavone glycosides together, it becomes possible to convert them into isoflavone aglycones with high efficiency in the intestine.

[0017] In this specification, the "lactic acid bacteria identified by deposit number NITE P-755" was deposited on May 14, 2009, at the Patent Microorganisms Depositary, National Institute of Technology and Evaluation, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture, under the deposit number NITE P-755. In this specification, the lactic acid bacteria identified by deposit number NITE P-755 may be referred to as "Pediococcus sp. KB1" or "KB1". For the culture conditions, mycological properties, and other details of the lactic acid bacteria according to the present invention, reference is made to the description in JP-A-2011-41499.

[0018] As a result of intensive research, the inventors of the present invention newly discovered that the "lactic acid bacteria identified by deposit number NITE P-755" having an immunostimulatory effect and gastric juice tolerance has a new use (described later) of converting isoflavone glycosides into isoflavone aglycones, leading to the present invention.

[0019] In this specification, the "lactic acid bacteria identified by deposit number NITE P-755" is viable cells. Here, viable cells refer to live lactic acid bacteria, and include the culture broth of lactic acid bacteria, suspensions of the culture broth, crude purified products, purified products, and also cell powders obtained by drying these live lactic acid bacteria by freeze-drying, spray-drying, etc., and are not limited as long as they are in a live state.

[0020] In this specification, the "lactic acid bacterium identified by deposit number NITE P-755" can be cultured under the culture conditions described in JP-A-2011-41499, but it can be grown by culturing in any medium suitable for the growth of the lactic acid bacterium strain (for example, MRS medium (manufactured by BD), LBS medium, Rogosa medium, etc.) at a predetermined temperature for a predetermined time. The culture may be static culture, or if the culture solution is liquid, it may be shaking culture using a shaker or stirring culture using a stirrer. Also, the culture system may be in an anaerobic state or an aerobic state. Further, the cells can be collected, for example, by centrifuging the culture (culture solution) under predetermined conditions after culturing. Also, the "lactic acid bacterium identified by deposit number NITE P-755" used in the present invention may be cultured (fermented) in the presence of materials such as soy milk, vegetables, fruits, etc. As described above, the cells can be collected by centrifugation after culturing. In the present invention, the culture (ferment) obtained in this way, the collected cells, the suspension or concentrate of the culture or cells, and also those obtained by drying and powdering the culture, cells, suspension, and concentrate obtained in this way by freeze-drying, spray-drying, etc. can also be used. These preparations can be carried out according to methods known in the art.

[0021] In this specification, "isoflavone" is one of the polyphenols contained in leguminous plants such as soybeans and kudzu, and is a flavonoid having an isoflavone as the basic skeleton.

[0022] In this specification, "isoflavone glycoside" is a glycoside in which sugar is covalently bonded to isoflavone, and examples thereof include genistin, daidzin, glycitin, etc. The "isoflavone glycoside" may be malonylated, acetylated, etc. In this specification, the "isoflavone glycoside" is preferably an isoflavone glycoside contained in soybeans, and more preferably an isoflavone glycoside contained in soy milk.

[0023] In this specification, "isoflavone aglycone" refers to a compound obtained by cleaving the sugar from an isoflavone glycoside, and may sometimes be simply referred to as "aglycone." For example, the aglycone obtained by cleaving the sugar from genistin (an isoflavone glycoside) is genistein, the aglycone obtained by cleaving the sugar from daidzin (an isoflavone glycoside) is daidzein, and the aglycone obtained by cleaving the sugar from glycitin (an isoflavone glycoside) is glycitein.

[0024] In this specification, "converting isoflavone glycosides to isoflavone aglycones" refers to the process of cleaving sugar from isoflavone glycosides to convert them to isoflavone aglycones, and may be simply referred to as "aglyconization." There are no particular restrictions on the number of sugar units to be cleaved from isoflavone glycosides, but monosaccharides are preferred. For example, to determine that the conversion to isoflavone aglycones has occurred, the content of isoflavone glycosides and isoflavone aglycones can be measured in test groups with and without KB1 addition, and if the content of isoflavone glycosides decreases and the content of isoflavone aglycones increases in the group with KB1 addition compared to the group without KB1 addition, it can be determined that the conversion from isoflavone glycosides to isoflavone aglycones has occurred by KB1.

[0025] In this specification, "aglyconization ability" refers to the degree of ability to convert isoflavone glycosides into isoflavone aglycones.

[0026] (2. Composition for converting isoflavone glycosides to isoflavone aglycones) The composition for converting isoflavone glycosides to isoflavone aglycones according to the present invention contains lactic acid bacteria (KB1) identified by accession number NITE P-755.

[0027] The composition of the present invention, by containing KB1, can efficiently convert isoflavone glycosides into isoflavone aglycones. For example, by ingesting the composition of the present invention together with isoflavone glycosides, it becomes possible to efficiently convert them into isoflavone aglycones in the intestines.

[0028] The compositions of the present invention may include foods and beverages, health foods, pharmaceuticals, or quasi-drugs.

[0029] When the composition of the present invention is a food or beverage, it can be processed by conventional methods into a form suitable for consumption, such as granules, tablets, capsules, gels, creams, pastes, suspensions, aqueous solutions, emulsions, or powders. Excipients, binders, lubricants, colorants, disintegrants, thickeners, preservatives, stabilizers, pH adjusters, etc., commonly used in food and beverages, can also be added. Furthermore, sugars, sugar alcohols, salts, fats and oils, amino acids, organic acids, glycerin, etc., can be added to improve the taste, provided that the effects of the present invention are not impaired. When incorporating the food or beverage of the present invention into existing food or beverages, the base food or beverage can be appropriately selected as long as it is capable of achieving the effects of the present invention.

[0030] When the composition of the present invention is a health food, it can be used, for example, as a food for specified health uses, a food with nutritional function claims, a food with functional claims, a supplement, a drink, etc., and can be processed by conventional methods into a form suitable for consumption, such as granules, tablets, capsules, gels, creams, pastes, suspensions, aqueous solutions, emulsions, or powders. Furthermore, excipients, binders, lubricants, colorants, disintegrants, thickeners, preservatives, stabilizers, pH adjusters, etc., which are commonly used in food and beverages, can be added. In addition, sugars, sugar alcohols, salts, oils and fats, amino acids, organic acids, glycerin, etc., can be added to improve the taste, to the extent that they do not impair the effects of the present invention.

[0031] When the composition of the present invention is a pharmaceutical or quasi-drug, it can be prepared by conventional methods into dosage forms such as tablets, granules, powders, capsules, syrups, and injections, and an appropriate drug delivery system (DDS) may be used. Excipients, binders, lubricants, colorants, disintegrants, thickeners, preservatives, stabilizers, pH adjusters, etc., commonly used in pharmaceuticals or quasi-drugs, may also be added. The dosage can be appropriately determined according to the age, weight, and symptoms of the subject. The method of administration can be any of the following: during meals, after meals, before meals, between meals, or before bedtime.

[0032] The composition of the present invention may, for example, contain isoflavone aglycones converted from isoflavone glycosides by KB1. For example, if the isoflavone glycoside is derived from soy milk, the composition of the present invention may contain a soy milk ferment product obtained by inoculating soy milk with KB1 and fermenting it under predetermined conditions, or it may contain a soy milk ferment product powder obtained by freeze-drying the soy milk ferment product, for example.

[0033] (3. Method for converting isoflavone glycosides to isoflavone aglycones) The present invention provides a method for converting isoflavone glycosides to isoflavone aglycones, which includes the step of contacting the isoflavone glycoside with lactic acid bacteria (KB1) identified by accession number NITE P-755.

[0034] There are no particular limitations on the method for contacting isoflavone glycosides with KB1, as long as the effects of the present invention are achieved. For example, one method is to inoculate a liquid containing isoflavone glycosides with KB1 and cultivate it under predetermined conditions. For example, when using isoflavone glycosides derived from soy milk, one method is to inoculate soy milk with KB1 and ferment it under predetermined conditions.

[0035] (4. Method using lactic acid bacteria identified by accession number NITE P-755) The method using lactic acid bacteria (KB1) identified by accession number NITE P-755 is a method for converting isoflavone glycosides to isoflavone aglycones.

[0036] The method of the present invention, by using KB1, can efficiently convert isoflavone glycosides into isoflavone aglycones.

[0037] (4. Conclusion) As described above, according to the present invention, isoflavone glycosides can be converted to isoflavone aglycones with high efficiency by KB1, which has high aglycone conversion ability. Even when the aglycone conversion ability by intestinal bacteria is low and the absorption of isoflavone aglycones in the body is not good, for example, by taking an agent or composition containing KB1 of the present invention together with isoflavone glycosides, it is possible to convert them to isoflavone aglycones with high efficiency in the intestines. Since isoflavones generally need to be efficiently ingested for the maintenance of women's health, the present invention can be suitably used as an agent, composition, and method that can convert isoflavone glycosides to isoflavone aglycones with high efficiency. [Examples]

[0038] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples.

[0039] We investigated the aglycone conversion ability of various lactic acid bacteria to isoflavone glycosides contained in soy milk.

[0040] The following lactic acid bacteria were used in the aglycone formation test. - "KB1": Pediococcus sp. KB1 (NITE P-755) (Example) - "OB2": Enterococcus sp. OB-2 (isolated from perilla (plant)) (Comparative example) - "CS1117": Leuconostoc mesenteroides CS-1117 (isolated from cheese) (comparative example)

[0041] (Conditions for culturing lactic acid bacteria) Lactic acid bacteria solution (turbidity (wavelength 660nm): approximately 6-10) cultured in MRS medium at 35±2°C for 24-48 hours was to which glycerol was added to achieve a final concentration of 10%. This solution was then dispensed into cryotubes in 1 mL portions and stored frozen at -80°C. The frozen lactic acid bacteria strains were gently thawed at room temperature, and then 1 mL of each strain was inoculated into 9 mL of MRS liquid medium sterilized by autoclaving at 121°C for 15 minutes. The mixture was then incubated statically at 35±1°C for 24 hours.

[0042] (Adjusting the turbidity of the lactic acid bacteria solution) As described above, the supernatant of each lactic acid bacterium cultured under static conditions was removed by centrifugation at 3,500 rpm for 5 minutes. Then, 10 mL of sterile physiological saline was added for suspension, and the supernatant was removed again by centrifugation at 3,500 rpm for 5 minutes. This procedure was repeated three times to wash the bacterial cells. After washing, 10 mL of sterile physiological saline was added to the lactic acid bacteria and thoroughly suspended. The turbidity (wavelength 660 nm) of the lactic acid bacteria solutions diluted 10-fold and 100-fold was measured by a standard method. Based on the measurement results, the turbidity of the lactic acid bacteria solution was adjusted using sterile physiological saline to 3.00.

[0043] (Soy milk fermentation) Unprocessed soy milk was dispensed into sterilized culture bottles in 250 mL portions, and 10 mL of each lactic acid bacteria solution, adjusted to a turbidity of 3.00 as described above, was inoculated. These were then subjected to soy milk fermentation by shaking culture at 35 ± 2 °C and 120 rpm for 48 ± 2 hours. The pH measurements during soy milk fermentation (at culture times of 0, 24, 48, and 52 hours) are shown in Table 1 and Figure 1. From these results, it was confirmed that for all three strains, KB1, OB2, and CS1117, the pH was below 5.0 after 48 hours of culture, indicating that good lactic acid fermentation was taking place.

[0044] [Table 1]

[0045] (Preparation of freeze-dried powder of cultured fermented product) As described above, soy milk fermentation was performed to obtain cultured fermented products of each lactic acid bacterium. After pre-freezing the cultured fermented products at -80°C, they were freeze-dried using a freeze-dryer until no moisture was detected, and freeze-dried powders of the cultured fermented products were prepared. As freeze-dried powders of the cultured fermented products, 22.57g of KB1, 22.26g of OB2, and 23.7g of CS1117 were obtained.

[0046] (Measurement of isoflavone glycoside and isoflavone aglycone concentrations) As described above, the isoflavone glycosides and isoflavone aglycones (mg / 100g of freeze-dried cultured fermented product powder) were measured in the freeze-dried powder of the cultured fermented product obtained. The isoflavone glycosides measured were genistin and daidzin, and the isoflavone aglycones measured were genistein and daidzein. The measurement of isoflavone glycosides and isoflavone aglycones was requested from the Japan Food Research Laboratories, and the measurements were performed by high-performance liquid chromatography (HPLC) according to the sample extraction method and measurement method of the same organization. As a control, the concentrations of isoflavone glycosides and isoflavone aglycones in unadjusted soy milk without inoculation with lactic acid bacteria were measured in the same manner.

[0047] When lactic acid bacteria ferment soy milk, they utilize isoflavone glycosides (genistin, daidzein), converting them into isoflavone aglycones (genistein, daidzein), thus increasing their content. Therefore, the higher the isoflavone aglycone content, the higher the aglycone conversion ability of the lactic acid bacteria.

[0048] (result) The control soy milk contained 47 mg / 100g and 20 mg / 100g of isoflavone glycosides genistin and daidzein, respectively, indicating a high content of isoflavone glycosides. In contrast, it contained only 1.9 mg / 100g and 0.9 mg / 100g of aglycones genistein and daidzein, respectively, indicating a very low aglycone content. In the comparative example CS1117, the aglycone content of genistein was 5.1 mg / 100g and daidzein was 1.4 mg / 100g, which were 2.7 times and 1.6 times higher than the control, respectively. Furthermore, in the comparative example OB2, the aglycone content of genistein was 18 mg / 100g and daidzein was 6.9 mg / 100g, which were 9.4 times and 7.7 times higher than the control, respectively. On the other hand, in the example KB1, the aglycones genistein and daidzein were 34 mg / 100g and 13 mg / 100g, respectively, which were 17.8 times and 14.4 times higher, respectively, than the control, indicating a significantly higher aglycone content. Furthermore, since the isoflavone glycosides genistin and daidzin were not detected in the example KB1, it was suggested that KB1 converted most of the isoflavone glycosides contained in soy milk into aglycones.

[0049] [Table 2]

[0050] Based on the above, KB1 in this embodiment was shown to be a lactic acid bacterium with excellent ability to convert isoflavone glycosides in soy milk into isoflavone aglycones, and to have remarkably high aglycone conversion ability.

Claims

1. An agent for converting isoflavone glycosides to isoflavone aglycones, containing lactic acid bacteria identified by accession number NITE P-755.

2. A composition for converting isoflavone glycosides to isoflavone aglycones, containing lactic acid bacteria identified by accession number NITE P-755.

3. A method for converting an isoflavone glycoside to an isoflavone aglycone, comprising the step of contacting the isoflavone glycoside with lactic acid bacteria identified by accession number NITE P-755.

4. A method for converting isoflavone glycosides to isoflavone aglycones using lactic acid bacteria identified by accession number NITE P-755.

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