Composition for improving short-term memory

Abstract

To provide a novel composition for improving short-term memory.SOLUTION: We have conducted intense study to discover a composition for improving short-term memory, containing at least one of sulforaphane, glucoraphanin, sulforaphane and glucoraphanin as a contributing component. The composition can be administered to or taken by a subject to enhance the short-term memory, prevent worsening of the short-term memory, and improve the worsened short-term memory.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition for improving short-term memory ability. [Background technology]

[0002] In Japan, an increase in dementia is predicted due to the aging society, and its prevention is an urgent social issue. Therefore, active research is being conducted into the mechanisms of dementia onset and its treatment. Numerous compounds have been suggested to be effective against dementia, and sulforaphane is one of them. Patent Document 1 discloses that sulforaphane has an inhibitory effect on tau protein aggregation and suggests that it may contribute to the treatment or prevention of neurodegenerative diseases such as Alzheimer's disease.

[0003] Furthermore, sulforaphane has been reported to improve impaired spatial memory in models of memory impairment caused by inflammation or drugs. Non-Patent Document 1 discloses that intraperitoneal administration of sulforaphane suppresses the decline in spatial memory induced by intraperitoneal administration of LPS. Non-Patent Document 2 discloses that oral administration of sulforaphane suppresses the decline in spatial memory induced by intraperitoneal administration of scopolamine.

[0004] However, the effects of sulforaphane and its analogs on memory, particularly short-term memory, in healthy individuals have not been clarified. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2018-104414 [Non-patent literature]

[0006] [Non-Patent Document 1] Gao, et al., Neuroscience. 388, 357-366, 2018 [Non-patent document 2] Lee, et al., Pharmacol Res. 85, 23-32, 2014 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem to be solved by the present invention is to provide a novel composition for improving short-term memory ability. [Means for solving the problem]

[0008] Based on the above, the present inventors have conducted extensive research and discovered a composition for improving short-term memory, which contains at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin as a contributing component. That is, by administering or ingesting a composition containing at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin as a contributing component, it is possible to improve short-term memory. From this perspective, the present invention is defined as follows.

[0009] The contributing component of the composition for improving short-term memory according to the present invention is at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin. The time period for which short-term memory is retained is 30 minutes or more. Furthermore, the short-term memory improving effect persists for at least six months during the administration or ingestion period of the composition. The contributing component of the composition for preventing a decline in short-term memory according to the present invention is at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin. The time period for which short-term memory is retained is 30 minutes or more. Furthermore, the short-term memory improving effect persists for at least six months during the administration or ingestion period of the composition.

[0010] The contributing component of the composition for improving short-term memory according to the present invention is at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin. The short-term memory is retained for 30 minutes or more. Furthermore, the short-term memory improvement effect of the composition is maintained for at least six months during the administration or ingestion period of the composition. [Effects of the Invention]

[0011] The present invention provides a novel composition for improving short-term memory, preventing a decline in short-term memory, and improving short-term memory. The components of the composition, sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin, are all materials that can be used as food ingredients, and the composition of the present invention has fewer side effects than conventional pharmaceuticals containing non-natural compounds, making it highly safe. [Brief explanation of the drawings]

[0012] [Figure 1] Schematic diagram of the arm used in the test [Figure 2] Ratio (%) of time spent in the novel arm to total time spent in the arms during the test trial [Figure 3] During the test trial, the time (seconds) elapsed from the first time the subject reached the center to the time the subject entered the novel arm. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Composition of the Present Invention> The composition of the present invention is a composition for improving short-term memory ability, a composition for preventing a decline in short-term memory ability, and a composition for improving short-term memory ability, and contains at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin as a contributing component.

[0014] <Short-term memory ability> Short-term memory ability is a cognitive function related to memory, and is the ability to retain memories for a short period of time. Short-term memory is recognized as meaningful and retained from sensory memory, which is a very short-term memory. Short-term memory is believed to be retained in the hippocampus for a certain period of time. The retention time of short-term memory is longer than that of sensory memory, generally ranging from several tens of seconds to several hours. In the examples described below, it was confirmed that short-term memory was retained for 30 minutes or more by ingesting the composition of the present invention. Short-term memory is a memory process that temporarily retains information and is generally believed to disappear quickly, but can be selectively converted into long-term memory, which is a stable memory, by receiving some kind of stimulus, etc.

[0015] Here, "improvement of short-term memory ability" refers to an improvement in short-term memory ability from a normal state. Specifically, this can be confirmed by observing an improvement in short-term memory ability when the composition of the present invention is administered or ingested by an individual with normal short-term memory ability, compared to when a control composition not containing the contributing component is administered or ingested. "Prevention of decline in short-term memory ability" refers to suppression of decline in short-term memory ability. Specifically, this can be confirmed by observing a lower degree of decline in short-term memory ability after a certain period of ingestion when the composition of the present invention is administered or ingested by an individual currently exhibiting decline in short-term memory ability or an individual who will experience decline in short-term memory ability in the future, compared to when a control composition not containing the contributing component is administered or ingested. In other words, this can be confirmed by observing a suppression of decline in short-term memory ability.

[0016] Furthermore, "improvement of short-term memory ability" means that the decline in short-term memory ability is suppressed and the short-term memory ability is brought to a state equivalent to or better than normal. Specifically, when the composition of the present invention is administered or ingested by an individual with a decline in short-term memory ability, the short-term memory ability of the individual can be confirmed by being equal to or better than that of an individual with normal short-term memory ability who is administered or ingested with a control composition that does not contain a contributing component.

[0017] <Sulforaphane and Glucoraphanin> Glucoraphanin is a type of glucosinolate and a precursor of sulforaphane. It is hydrolyzed by the enzyme myrosinase to form sulforaphane. Furthermore, when glucoraphanin is ingested by mammals such as humans, it is converted to sulforaphane by enzymes in intestinal bacteria and absorbed from the intestinal tract. Glucoraphanin is known to be abundant in Brassicaceae plants. In the present invention, glucoraphanin may be contained in a purified form in a preparation, food composition, or food or beverage, or in one or more forms selected from Brassicaceae plants, their extracts or fractions, and their pulverized products. The structural formula of glucoraphanin is shown below in (1), and the structural formula of sulforaphane is shown below in (2).

[0018] [ka]

[0019] From the viewpoint of improving the efficiency of metabolism in the body, the composition of the present invention can further preferably contain myrosinase. The enzyme activity of myrosinase relative to the amount of glucoraphanin (myrosinase activity (UNIT) / glucoraphanin (mg)) may have a lower limit of 0.0001 (UNIT / mg) or more, preferably 0.001 (UNIT / mg) or more, and an upper limit of 0.022 (UNIT / mg) or less, preferably 0.01 (UNIT / mg) or less.

[0020] Furthermore, myrosinase may be chemically synthesized or natural, and is not particularly limited, but natural myrosinase is preferred, and plant-derived myrosinase is more preferred. Examples of such plants include Brassicaceae plants, more specifically, mustard, radish, wasabi, etc. Myrosinase may be contained in a purified form in an agent or food or drink, or in one or more forms selected from Brassicaceae plants, their extracts or fractions, and their pulverized products.

[0021] <Sulforaphen and Glucoraphenin> Glucoraphenin is a glucosinolate and a precursor of sulforaphen. It is hydrolyzed by the enzyme myrosinase to form sulforaphen. Furthermore, when glucoraphenin is ingested by mammals such as humans, it is converted to sulforaphen by the enzymes of intestinal bacteria and absorbed from the intestinal tract. Glucoraphenin is known to be contained in large amounts in Brassicaceae plants, particularly radishes and their leaves and seeds. In the present invention, glucoraphenin may be contained in a purified form in a preparation, food composition, or food or beverage, or in one or more forms selected from Brassicaceae plants, their extracts or fractions, and their pulverized products. The structural formula of glucoraphenin is shown below in (3), and the structural formula of sulforaphene is shown below in (4).

[0022] [ka]

[0023] Glucoraphenin is structurally similar to glucoraphanin, and therefore is expected to have similar actions and effects to glucoraphanin. For example, it has been reported that glucoraphenin contributes to the activity of phase II enzymes, which are indicators of the activation of the transcription factor Nrf2 (NF-E2-related-factor 2) (Barillari et al., J Agric Food Chem. 55(14), 5505-11, 2007). In addition, Nrf2 acts as a stress inhibitor in response to the occurrence of oxidative stress, etc. Itoh et al., Genes Dev. 13(1), 76-86, 1999), and has been reported to increase the gene expression of antioxidant enzymes (Ishii et al., J Biol Chem. 275(21), 16023-9, 2000) and detoxification metabolic enzymes (Itoh et al., Biochem Biophys Res Commun. 236(2), 313-22, 1997), as well as to decrease the gene expression of cytokines that cause inflammation (Kobayashi et al., Nat Commun. 7, 11624, 2016 and Itoh et al., Mol Cell Biol. 24(1), 36-45, 2004), which share these actions with glucoraphanin. Furthermore, it has been reported that activation of Nrf2 in the area of ​​cognitive function suppresses oxidative stress and inflammation in the brain of Alzheimer's disease model mice, improving cognitive impairment (Uruno et al., Mol Cell Biol. 40(6), e00467-19, 2020). Based on these findings, it is inferred that glucoraphenin has the same short-term memory-improving effect as glucoraphanin and sulforaphane.

[0024] The composition of the present invention can further preferably contain myrosinase from the viewpoint of improving the efficiency of metabolism in the body. The enzyme activity of myrosinase relative to the amount of glucoraphenin (myrosinase activity (unit) / glucoraphenin (mg)) may have a lower limit of 0.0001 (unit / mg) or more, preferably 0.001 (unit / mg) or more, and an upper limit of 0.022 (unit / mg) or less, preferably 0.01 (unit / mg) or less.

[0025] Furthermore, myrosinase may be chemically synthesized or natural, and is not particularly limited, but natural myrosinase is preferred, and plant-derived myrosinase is more preferred. Examples of such plants include Brassicaceae plants, more specifically, mustard, radish, wasabi, etc. Myrosinase may be contained in a purified form in an agent or food or drink, or in one or more forms selected from Brassicaceae plants, their extracts or fractions, and their pulverized products.

[0026] <Brassicaceae Plants> Brassicaceae plants are not particularly limited, but examples include broccoli, kale, cabbage, cauliflower, takana (leaf mustard greens), rapeseed, mustard greens, daikon radish, daikon radish leaves, nozawana (leaf mustard greens), komatsuna (Japanese mustard spinach), Chinese cabbage, Brussels sprouts, petit vert, snow radish, and plants produced by appropriate hybridization of these. The plant part may be a plant growth body (buds, leaves, stems, roots, flowers, etc.), a sprout (germinated body), or a seed, and is not particularly limited. Among these, broccoli, which belongs to the genus Brassica in the Brassicaceae family, is more preferred. Furthermore, broccoli sprouts or seeds are particularly preferred due to their high content of sulforaphane and glucoraphanin.

[0027] <Broccoli Sprout Extract> When extracting at least one of sulforaphane and glucoraphanin from broccoli sprouts, any number of days after germination may be used as long as the sprouts are not yet matured, at which point the content per unit weight of sulforaphane and glucoraphanin decreases significantly. However, sprouts are preferably used 1 to 10 days after germination, more preferably 1 to 3 days after germination. Broccoli sprouts with a sulforaphane and glucoraphanin content of 50 to 350 mg / 100 g (wet weight), more preferably 150 to 330 mg / 100 g (wet weight), and even more preferably 250 to 300 mg / 100 g (wet weight) are preferably used.

[0028] <Obtaining Contributing Components> At least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin can be obtained from Brassicaceae plants, including broccoli sprouts, by well-known methods. Isolated and purified sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin are commercially available, and these commercially available products can also be used. Examples of commercially available products include, but are not limited to, sulforaphane (Funakoshi Co., Ltd.) and L-Sulforaphene (Cayman Chemical Company).

[0029] <Extraction of glucoraphanin and glucoraphenin> For example, glucoraphanin and glucoraphenin can be obtained by extracting part or the whole plant, either as is or dried and crushed, with a solvent or the like. Examples of solvents include water, lower monohydric alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, etc.), liquid polyhydric alcohols (glycerin, propylene glycol, 1,3-butylene glycol, etc.), lower esters (ethyl acetate, etc.), hydrocarbons (benzene, hexane, pentane, etc.), ketones (acetone, methyl ethyl ketone, etc.), ethers (diethyl ether, tetrahydrofuran, dipropyl ether, etc.), acetonitrile, etc., and one or more of these can be used.

[0030] Considering that the composition of the present invention is orally administered or ingested, water, ethanol, or aqueous ethanol are particularly preferred as the extraction solvent. Examples of preferred extraction methods include extraction with hot water (90-100°C) for 10-50 minutes, or extraction with 0-100% aqueous ethanol by volume at room temperature or with heating for 1-10 days, and the resulting extract may be further fractionated and purified. Alternatively, glucoraphanin and glucoraphenin may be extracted by supercritical extraction.

[0031] <Method for Obtaining Sulforaphane from Glucoraphanin> Sulforaphane can be obtained from glucoraphanin by reacting glucoraphanin with myrosinase, and the method is not limited thereto. For example, a Brassicaceae plant containing glucoraphanin can be crushed, ground, pulverized, sheared, squeezed, or the like without heating to cause the glucoraphanin to react with endogenous myrosinase and be metabolized to sulforaphane, or myrosinase can be added to glucoraphanin to metabolize it to sulforaphane. Sulforaphane can be obtained from a raw material containing sulforaphane metabolized from glucoraphanin by these methods using a method similar to that for glucoraphanin (e.g., the extraction method described above).

[0032] <Method for Obtaining Sulforaphene from Glucoraphenin> The method for obtaining sulforaphene from glucoraphenin is the same as the method for obtaining sulforaphane from glucoraphanin described above.

[0033] <Measurement of glucoraphanin and glucoraphenin concentrations> The concentration of glucoraphanin in the composition of the present invention can be measured by methods well known to those skilled in the art. For example, high-performance liquid chromatography (HPLC) can be used, specifically, the method of Fahey et al. (Fahey et al., Proc. Natl. Acad. Sci. USA, 94, 10367-10372, 1997) can be used. The concentration of glucoraphenin can be measured by the same method as for glucoraphanin.

[0034] <Measurement of Sulforaphane and Sulforaphene Concentrations> The concentrations of sulforaphane and sulforaphene in the composition can be measured by methods well known to those skilled in the art, such as high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS), specifically, the methods of Han et al. or Baenas et al. (Han et al., Int J Mol Sci. 12(3), 1854-1861, 2011; Baenas et al., Food Res Int. 100(Pt1), 497-503, 2017).

[0035] <Form of Composition> The composition of the present invention can be administered as a pharmaceutical preparation or ingested as a food composition or food or beverage. Specifically, it can be a pharmaceutical preparation, food composition, or food or beverage for humans or animals, or a material or preparation to be incorporated into such a pharmaceutical preparation, food composition, or food or beverage. The food composition or food or beverage includes food compositions, food or beverages, functional foods, foods for specified health uses, foods for medical patients, and supplements that are based on the concept of improving, preventing, or improving short-term memory, and are labeled as such as necessary. Examples of labeling methods include, but are not limited to, "improving short-term memory," "improving short-term memory," "enhancing short-term memory," "strengthening short-term memory," "maintaining short-term memory," "preventing short-term memory decline," "improving short-term memory," "restoring short-term memory," "for those concerned with short-term memory decline," "helping with short-term memory," and "for those concerned with forgetfulness."

[0036] These indications can be attached to container packaging means by known methods, or the above explanations can be displayed or distributed in product advertisements, price lists, or transaction documents, or information containing these contents can be provided electromagnetically (such as via the Internet), etc. Furthermore, the composition of the present invention can be used to delay the onset of dementia, Alzheimer's disease, or Parkinson's disease, alleviate the symptoms thereof, reduce the severity, or slow or stop the progression thereof.

[0037] <Preparation> Preferred administration forms of the composition of the present invention as a preparation include oral administration in the form of tablets, coated tablets, capsules, granules, powders, solutions, syrups, emulsions, etc. However, parenteral administration forms are not excluded, and local tissue administration, subcutaneous, intradermal, intramuscular, or intravenous administration by injection, or intranasal administration by volatilizing the active ingredient, etc. may also be used. Formulations can be made using known adjuvants commonly used in the pharmaceutical formulation technical field, such as excipients, binders, disintegrants, lubricants, colorants, flavorings, solubilizers, suspending agents, and coating agents. The composition may also be in the form of a drug or quasi-drug.

[0038] <Food Composition> Examples of forms in which the food composition of the present invention can be ingested include, but are not limited to, beverages (juice, black tea, green tea, coffee, carbonated drinks, sports drinks, soft drinks, etc.), confectioneries (gum, caramel, candy, chocolate, cookies, biscuits, snacks, jelly, gummy candy, candy tablets, etc.), noodles (soba, udon, ramen, etc.), dairy products (milk, ice cream, yogurt, etc.), seasonings (miso, soy sauce, dressing, etc.), soups, and other general foods and processed foods, health foods (tablets, capsules, etc.), and nutritional supplements (supplements, energy drinks, etc.).

[0039] These food compositions can contain various ingredients depending on their type, and food additives such as glucose, fructose, sucrose, maltose, raffinose, sorbitol, stevioside, corn syrup, lactose, citric acid, tartaric acid, malic acid, succinic acid, lactic acid, L-ascorbic acid, dl-α-tocopherol, sodium erythorbate, glycerin, propylene glycol, glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, gum arabic, carrageenan, casein, gelatin, pectin, agar, B vitamins, nicotinamide, calcium pantothenate, amino acids, calcium salts, colorants, flavorings, and preservatives can be used as desired.

[0040] <Foods and Drinks> Examples of forms in which the composition of the present invention can be ingested as foods and drinks include fresh foods (raw vegetables), beverages (juice, coffee, black tea, green tea, carbonated drinks, sports drinks, green juice, etc.), sweets (gum, candy, caramel, chocolate, cookies, snacks, jelly, gummy candy, candy tablets, etc.), noodles (soba, udon, ramen, etc.), dairy products (milk, ice cream, yogurt, etc.), seasonings (miso, soy sauce, etc.), soups, and other general foods, as well as health foods (tablets, capsules, etc.), and nutritional supplements (supplements, energy drinks, etc.).

[0041] Depending on the type, various ingredients can be blended, for example, glucose, fructose, sucrose, maltose, sorbitol, corn starch, dextrin, stevioside, corn syrup, lactose, citric acid, tartaric acid, malic acid, succinic acid, lactic acid, L-ascorbic acid, dl-α-tocopherol, sodium erythorbate, glycerin, propylene glycol, glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose Food additives such as fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, cellulose, gum arabic, carrageenan, casein, gelatin, pectin, agar, B vitamins, nicotinamide, calcium pantothenate, amino acids, calcium salts, colorings, flavorings, and preservatives can be used as desired.

[0042] <Contributing ingredients> A contributing ingredient is a substance that affects the physiological functions of the body. In foods for specified health uses and foods with functional claims, the term "contributing ingredients" corresponds to so-called "contributing ingredients" and "functional contributing ingredients." In the case of pharmaceuticals and quasi-drugs, it corresponds to so-called "active ingredients."

[0043] <Content of contributing components> When the composition of the present invention is used as an agent, it is not particularly limited, but preferably contains at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin in a total amount of 0.03% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 5% by mass or more.

[0044] Furthermore, when the composition of the present invention is used as a food composition or a food or beverage product, it is not particularly limited, but preferably contains at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin in a total amount of 0.01% by mass or more, more preferably 0.04% by mass or more, and particularly preferably 0.25% by mass or more.

[0045] <Dosage / Intake> When the subject is a human, the dosage or intake of the composition of the present invention varies depending on the subject's gender, symptoms, age, and administration method. However, a daily dose of at least one of sulforaphane, glucoraphanin, sulforaphen, or glucoraphenin is generally 24 mg or more for an adult (body weight approximately 60 kg), with 30 mg or more being preferred to ensure sufficient efficacy. This daily amount can be administered or ingested all at once or in divided doses, and may be administered before, after, or between meals. The administration or intake period is not particularly limited, but continuous administration or intake for 12 weeks or more is preferred. The effect on short-term memory ability persists for at least 6 months with continuous administration or intake. The aforementioned daily dosage or intake amount varies depending on the form of the composition, but refers to the recommended daily intake indicated on the label or the amount contained in a single bottle of a beverage that is typically consumed in one sitting. [Example]

[0046] <Test> Short-term memory ability was evaluated in senescence-accelerated model mice, which show early decline in cognitive function, and control mice.

[0047] <Test animals> Male SAMP8 mice (Senescence Accelerated mouse Prone 8, SLC Japan) were used as senescence-accelerated model mice, and male SAMR1 mice (Senescence Accelerated mouse resistant 1, SLC Japan) were used as control mice.

[0048] <Test Food> A diet high in glucoraphanin was used as the test food. Specifically, a standard diet (#MF Powder, Oriental Yeast Co., Ltd.) supplemented with 2.2% (w / w) broccoli sprout (BS) extract (Ogawa Koryo Co., Ltd.) and 1.0% (w / w) mustard powder (#Y38, Minokusha Co., Ltd.) was used. The control food was a standard diet (#MF Powder, Oriental Yeast Co., Ltd.) without the BS extract or mustard powder. The test animals were allowed to ad libitum access to the test or control food continuously from 1 to 8 months of age.

[0049] <Evaluation of Short-Term Memory Ability> To evaluate the short-term memory ability of mice, we performed a modified Y-maze test, an extension of the Y-maze test. The Y-maze test utilizes mice's tendency to explore novel environments and evaluates spontaneous alternation behavior observed while exploring a device as a measure of short-term memory (Non-Patent Document 3: K. Taguma et al., Folia Pharmacol. Jpn., 130, 112-116 (2007); Non-Patent Document 4: Mamiya, Ukai, Br J Pharmacol., 134 (8), 1597-9, 2001). Like the Y-maze test, the modified Y-maze test also evaluates spontaneous alternation behavior as a measure of short-term memory (Non-Patent Document 5: Matheus et al., Behav Brain Res., 301, 43-54, 2016). Specifically, the modified Y-maze test involves training mice to memorize the maze once, preventing them from exploring some of the arms. After this, a novel arm is released, and exploratory behavior toward the novel arm is assessed. In this test, a modified Y-maze with arms equally spaced in three directions and of equal length was used, as shown in Figure 1. The three arms were designated "Arm 1," "Arm 2," and "Arm 3," and a movable partition was placed at the entrance to Arm 3. The partition is indicated by the dotted line in Figure 1, and the triangular area surrounded by Arms 1, 2, and 3 was designated the "center." The specific test procedure is as follows.

[0050] (1) Training trial 1) With arm 3 of the modified Y-maze closed with a partition, the mouse was removed from its cage and placed into arm 1. The mouse was placed with its head facing away from the center. 2) The mouse was allowed to explore for 5 minutes. 3) The mouse was removed from the modified Y-maze and returned to its original cage.

[0051] (2) Measurement trial 4) 30 minutes after the training trial, the partition of arm 3 of the modified Y-maze was removed, and the mouse was removed from its cage and placed back into arm 1. At this time, the mouse was placed so that its head was facing away from the center. 5) The mouse was allowed to explore for 5 minutes. 6) The mouse was removed from the modified Y-maze and returned to its original cage.

[0052] <Evaluation> After carrying out the above 1) to 6), short-term memory ability was evaluated using the following two evaluation indices. The first was to measure the time spent in each arm after reaching the center for the first time during the measurement trial, and to determine the ratio of the time spent in the novel arm (arm 3) to that of arms 1, 2, and 3 (excluding the center) (hereinafter referred to as "all arms"). The higher the ratio of the time spent in the novel arm, the more the mouse recognized that arm as a novel environment, and the higher the short-term memory ability was judged to be. The second was to measure the time required from reaching the center for the first time during the measurement trial to entering the novel arm (arm 3). The shorter the time required to enter the novel arm, the more the mouse recognized that arm as a novel environment, and the higher the short-term memory ability was judged to be. Table 1 shows the explanation for each category.

[0053] [Table 1]

[0054] <Results> The results of the above evaluation of short-term memory ability are shown below. 1. Ratio of time spent in the novel arm to total time spent in the arms during the measurement trial. For SAMR1 mice and SAMP8 mice that continued to consume the test food or control food, the ratio of time spent in the novel arm (arm 3) to total time spent in the arms after first reaching the center of the modified Y-maze during the measurement trial (excluding time spent in the center) is shown in Figure 2. In Figure 2, measurements were performed with N = 12 for category 1, N = 12 for category 2, N = 10 for category 3, and N = 9 for category 4. The average values ​​for each group are shown as bars, and the standard errors are indicated by error bars. Furthermore, in both the SAMR1 and SAMP8 groups, the ratio of time spent in the novel arm was higher in the group that consumed the test food (hereinafter referred to as the "sulforaphane group") compared to the group that consumed the control food (hereinafter referred to as the "control group").

[0055] In the SAMR1 group, the mean value of the sulforaphane group (Category 2) was higher than the mean value of the control group (Category 1), demonstrating that the test food has the effect of improving short-term memory. In the SAMP8 group, the mean value of the sulforaphane group (Category 4) was higher than the mean value of the control group (Category 3), demonstrating that the test food has the effect of preventing a decline in short-term memory. Furthermore, the mean value of the sulforaphane group (Category 4) in the SAMP8 group was higher than the mean value of the control group (Category 1) in the SAMR1 group, demonstrating that the test food has the effect of improving short-term memory.

[0056] 2. Time required from first reaching the center to entering the novel arm during the measurement trial Figure 3 shows the time required from first reaching the center to entering the novel arm during the measurement trial for SAMR1 mice and SAMP8 mice that continued to consume the test food or control food. In Figure 3, measurements were taken with N = 12 for category 1, N = 12 for category 2, N = 10 for category 3, and N = 9 for category 4. The average values ​​for each group are shown as bars, and the standard errors are indicated by error bars. In both the SAMR1 and SAMP8 groups, the time required to enter the novel arm was lower in the sulforaphane group compared to the control group.

[0057] In the SAMR1 group, the mean value of the sulforaphane group (Category 2) was lower than the mean value of the control group (Category 1), demonstrating that the test food had the effect of improving short-term memory. In the SAMP8 group, the mean value of the sulforaphane group (Category 4) was lower than the mean value of the control group (Category 3), demonstrating that the test food had the effect of preventing a decline in short-term memory. Furthermore, the mean value of the sulforaphane group (Category 4) in the SAMP8 group was lower than the mean value of the control group (Category 1) in the SAMR1 group, demonstrating that the test food had the effect of improving short-term memory. <Numerical Data> Table 2 shows the numerical data of the above test results, which are the mean ± standard error.

[0058] [Table 2] [Industrial Applicability]

[0059] One area in which the present invention is useful is the health food business.

Claims

1. A composition for preventing a decline in short-term memory, comprising at least one component selected from the group consisting of a Brassicaceae plant, an extract thereof or a fraction thereof, and a pulverized product thereof.

2. 2. The composition of claim 1, wherein the contributing component is at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin.

3. 3. The composition of claim 1 or 2, wherein the composition contains myrosinase.

4. A composition for improving short-term memory ability, comprising at least one component selected from the group consisting of a Brassicaceae plant, an extract thereof or a fraction thereof, and a pulverized product thereof, as a contributing component.

5. 5. The composition of claim 4, wherein the contributing component is at least one of sulforaphane, glucoraphanin, sulforaphen, and glucoraphenin.

6. 6. The composition of claim 4 or 5, wherein the composition contains myrosinase.

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