Memory disorder ameliorating agent

Abstract

The present invention provides a novel memory disorder ameliorating agent.　A PKCγ activity inhibitor is useful as an active ingredient for a memory disorder ameliorating agent.

Description

Memory impairment improver

[0001] The present invention relates to an agent for improving memory impairment.

[0002] It is known that memory impairment is caused by irreversible neurodegeneration, such as Alzheimer's disease. Because the cause of memory impairment is irreversible, it is not fundamentally reversible, and treatments can only slow the progression of the condition.

[0003] However, memory impairment is also known to be caused by other factors, such as depression, trauma, stress, and brain fog.

[0004] For example, Non-Patent Document 1 describes memory impairment as a neuropsychological symptom of depression, and that brain function in depression recovers in line with clinical recovery. Furthermore, memory impairment is a symptom of brain fog, which is rapidly increasing as a sequelae of COVID-19. Non-Patent Document 2 describes that brain fog often gradually improves over time, and Non-Patent Document 3 describes that, although there are individual differences, more than half of patients with this sequelae tend to experience symptom improvement within five months. Furthermore, Non-Patent Document 4 describes that the main symptom of dissociative amnesia caused by trauma or stress is memory impairment that does not correspond to normal forgetfulness, and that most patients regain lost memories and the amnesia resolves. In other words, memory impairment caused by these other factors is a symptom that can be expected to recover, and is fundamentally different from memory impairment caused by the above-mentioned irreversible neurodegeneration.

[0005] Yasumasa Okamoto, Brain Basis Related to the Pathogenesis of Depression, Journal of Psychiatry and Neurology, Vol. 111, No. 11 (2009), pp. 1330-1344 Kumiko Arai, What is Brain Fog, which is Rapidly Increasing as an Aftereffect of COVID-19? The Difference Between Dementia and Forgetfulness, [online], 2023 / 2 / 13, [Retrieved April 12, 2023], Internet <URL: https: / / nishiharu-clinic.com / 2023 / 02 / 13 / korona-bureinfogu / > Hideitsu Hatsumura, What is "Brain Fog," an Aftereffect of COVID-19? , [online], 2022 / 10 / 13, [Retrieved April 12, 2023], Internet <URL: https: / / utu-yobo.com / column / brain-fog / > David Spiegel, MSD Manual Professional Edition 08. Mental Disorders / Dissociative Disorders / Dissociative Amnesia, [online], March 2021, Merck & Co., Inc., Rahway, NJ, USA, [Retrieved April 12, 2020], Internet <URL: https: / / www.msdmanuals.com / ja-jp / %E3%83%97%E3%83%AD%E3%83%95%E3%82%A7%E3%83%83%E3%82%B7%E3%83%A7%E3%83%8 A%E3%83%AB / 08-%E7%B2%BE%E7%A5%9E%E9%9A%9C%E5%AE%B3 / %E8%A7%A3%E9%9B% A2%E7%97%87%E7%BE%A4 / %E8%A7%A3%E9%9B%A2%E6%80%A7%E5%81%A5%E5%BF%98>

[0006] To improve memory impairment, treatment typically involves eliminating the underlying cause. In other words, to improve memory impairment caused by depression, trauma, or stress, treatment must be directed at the underlying cause, and medications used for these treatments generally must be administered carefully, taking into account the risk of side effects. Furthermore, as the cause of brain fog, a sequela of COVID-19 infection, is unknown, there is no known treatment. Given this background, it is desirable to discover new compounds that are effective against memory impairment based on a clear mechanism of action.

[0007] Therefore, an object of the present invention is to provide an agent for improving memory disorders, the mechanism of action of which is clear.

[0008] The present inventors used DGKβ knockout mice, which were found to exhibit increased PKCγ phosphorylation in the brain (abnormal PKCγ activity), as a unique model of memory impairment, and found that administering a PKCγ activity inhibitor to the mice normalized PKCγ activity in the brain and improved memory impairment. The present invention was completed through further investigations based on this finding.

[0009] That is, the present invention provides the following aspects of the invention. Item 1. A memory impairment ameliorator containing a PKCγ activity inhibitor as an active ingredient. Item 2. The memory impairment ameliorator according to Item 1, wherein the PKCγ activity inhibitor is a flavonoid selected from the group consisting of scutellarin, baicalin, baicalein, luteonin, apigenin, apigenin glucoside, and salts thereof. Item 3. The memory impairment ameliorator according to Item 1 or 2, used to improve memory impairment not caused by accumulation of amyloid β. Item 4. The memory impairment ameliorator according to any one of Items 1 to 3, used to improve memory impairment not caused by exposure to general anesthesia. Item 5. The memory impairment ameliorator according to any one of Items 1 to 4, used to improve memory impairment not caused by cerebral infarction. Item 6. A food product comprising the memory impairment ameliorator according to any one of Items 1 to 5. Item 7. Use of a PKCγ activity inhibitor for the manufacture of a memory impairment ameliorator. Item 8. A PKCγ activity inhibitor for use in a memory impairment ameliorator. Item 9. A method for improving memory impairment, comprising the step of administering an effective amount of a PKCγ activity inhibitor to a subject in need of improvement of memory impairment.

[0010] According to the present invention, a new agent for improving memory impairment with a clear mechanism of action is provided.

[0011]

[0033] Figure 1 shows the results of confirming the memory impairment improving effect of mice orally administered with a PKCγ activity inhibitor using a Y-maze test.

[0034] Figure 1 shows the results of confirming PKC activity in the cerebral cortex of mice administered with a PKCγ activity inhibitor using Western blotting.

[0035] Figure 1 shows the results of confirming PKC activity in the hippocampus of mice administered with a PKCγ activity inhibitor using Western blotting.

[0036] Figure 1 shows the results of confirming the PKCγ activity inhibitory effect of various flavonoids.

[0012] 1. Memory impairment ameliorating agent The memory impairment ameliorating agent of the present invention is characterized by containing a PKCγ activity inhibitor as an active ingredient.

[0013] 1-1. Active Ingredients The PKCγ activity inhibitor is not particularly limited as long as it is a compound that has the effect of inhibiting the phosphorylation of PKCγ. Preferred PKCγ activity inhibitors used in the present invention include flavonoids such as scutellarin (formula (1) below), baicalin (formula (2) below), baicalein (formula (3) below), luteonin (formula (4) below), apigenin (formula (5) below), apigenin glucoside (formula (6) below), and salts thereof.

[0014]

[0015]

[0016] The salt is not particularly limited as long as it is pharmaceutically or food-wise acceptable, and examples thereof include alkali metal salts such as sodium salts.

[0017] The memory impairment improving agent of the present invention may contain one of these PKCγ activity inhibitors alone or a combination of two or more of them. Among these PKCγ activity inhibitors, preferred are scutellarin, baicalin, luteolin, and apigenin, more preferred are baicalin and luteolin, and even more preferred is baicalin.

[0018] The amount of the PKCγ activity inhibitor contained in the memory impairment ameliorating agent of the present invention is not particularly limited and can be appropriately set depending on the formulation form and / or specific use of the memory impairment ameliorating agent, and can be, for example, 40 to 100% by weight, preferably 60 to 90% by weight.

[0019] 1-2. Other Components In addition to the active ingredients, the memory impairment improving agent of the present invention may or may not further contain additives and / or bases depending on the formulation and intended use, as long as the effects of the present invention are not impaired. Such additives and bases, which may or may not be contained, are not particularly limited as long as they are pharmaceutically acceptable, and examples thereof include excipients, binders, disintegrants, lubricants, isotonicity agents, plasticizers, dispersants, emulsifiers, solubilizers, wetting agents, stabilizers, suspending agents, adhesives, gelling agents, coating agents, glossing agents, water, oils and fats, waxes, hydrocarbons, fatty acids, higher alcohols, esters, water-soluble polymers, surfactants, metal soaps, lower alcohols, polyhydric alcohols, pH adjusters, buffers, antioxidants, UV protection agents, preservatives, corrigents, fragrances, powders, thickeners, colorants, chelating agents, sweeteners, and the like. These additives may be used alone or in combination of two or more. The contents of these additives and bases are appropriately determined depending on the types of additives and bases used, the dosage form and use of the memory impairment ameliorating agent of the present invention, and the like.

[0020] In addition, the memory impairment improving agent of the present invention may or may not contain other nutritional components and / or pharmacological components in addition to the above-mentioned active ingredients, as long as the effects of the present invention are not impaired. Such nutritional components and pharmacological components are not particularly limited as long as they are pharmaceutically acceptable, and examples thereof include antacids, stomachic agents, digestive agents, intestinal regulators, antispasmodics, mucosal repair agents, anti-inflammatory agents, astringents, antiemetics, antitussives, expectorants, anti-inflammatory enzymes, sedatives, hypnotics, antihistamines, caffeine, cardiac diuretics, antibacterial agents, vasoconstrictors, vasodilators, local anesthetics, herbal extracts, vitamins, menthols, etc. These nutritional components and / or pharmacological components may be used alone or in combination of two or more. The content of these components is appropriately determined depending on the type of components used.

[0021] 1-3. Formulation of Preparation The form and properties of the memory impairment ameliorating agent of the present invention are not particularly limited as long as it contains the above-mentioned active ingredient.

[0022] The administration form of the memory impairment ameliorating agent of the present invention includes both oral and parenteral administration forms. Therefore, the memory impairment ameliorating agent of the present invention can be prepared as an oral agent, an injection, an intravenous drip, a nasal drop, or the like. Among these, the memory impairment ameliorating agent of the present invention is preferably an oral agent that can be easily administered (ingested) on a daily and / or continuous basis.

[0023] Furthermore, the memory impairment ameliorating agent of the present invention may be in liquid or solid form. Examples of liquid forms include solutions, drinks, emulsions, suspensions, spirits, syrups, elixirs, soft extracts, etc., and examples of solid forms include tablets, pills, powders, fine granules, granules, tablets, capsules (including hard capsules and soft capsules), troches, chewable tablets, dry extracts, etc. When the memory impairment ameliorating agent of the present invention is in solid form, it may be in a sustained- or sustained-release dosage form, or may be mixed with water or the like when administered or ingested.

[0024] The memory impairment improving agent of the present invention can also be used as an additive that adds value to foods, pharmaceuticals, quasi-drugs, etc. Foods to which the memory impairment improving agent of the present invention can be incorporated include general foods and beverages and health functional foods (including foods for specified health uses, foods with nutrient functions, and foods with functional claims, etc.). Among these, since the active ingredients of the memory impairment improving agent of the present invention contain flavonoids that can be ingested as food ingredients, it is preferable to incorporate the agent into health functional foods that can be easily ingested daily and / or continuously. Furthermore, since the memory impairment improving agent of the present invention exerts its efficacy based on the effect of reducing PKCγ phosphorylation (normalizing PKCγ activity), it is particularly preferable to incorporate the agent into foods for specified health uses or foods with functional claims.

[0025] 1-4. Manufacturing Method The manufacturing method of the memory impairment ameliorating agent of the present invention may be a conventional formulation procedure using the above-mentioned active ingredient and other ingredients to be blended as necessary, depending on the form, properties, and intended use.

[0026] 1-5. Uses The memory impairment ameliorating agent of the present invention is used for the purpose of ameliorating memory impairment through normalization of PKCγ activity. The memory impairment is not particularly limited as long as it is caused by inhibition of PKCγ activity. Examples include memory impairment caused by aging, depression, trauma, stress, and / or brain fog. In the memory impairment ameliorating agent of the present invention, the memory impairment is preferably a memory impairment not caused by either an irreversible neurodegenerative disease or amyloid beta accumulation, a memory impairment not caused by exposure to general anesthesia (particularly isoflurane), or a memory impairment not caused by cerebral infarction.

[0027] In addition, in memory disorders, the object of memory is not particularly limited, but preferably includes spatial memory (i.e., memory required for actions such as searching for a target, heading to a destination, and returning to the original location).

[0028] The dose of the memory impairment ameliorating agent of the present invention, in terms of the dose for humans, is, for example, 0.1 g / day / 60 kg or more, preferably 0.3 g / day / 60 kg or more, more preferably 0.5 g / day / 60 kg or more, and even more preferably 1 g / day / 60 kg or more, in terms of the amount of a PKCγ activity inhibitor.

[0029] The method of administration (ingestion) of the memory impairment improving agent of the present invention is not particularly limited, but for example, it can be administered orally or parenterally once or multiple times a day, and preferably orally once or 2 to 3 times a day.

[0030] 2. PKCγ Activity Inhibitors Among the isoflavones used as the PKCγ activity inhibitor active ingredient in the memory impairment improving agent of the present invention, baicalin (formula (2)), baicalein (formula (3)), luteonin (formula (4)), apigenin (formula (5)), apigenin glucoside (formula (6)), and salts thereof are not known to have PKCγ activity inhibitory effects. Therefore, the present invention also provides a PKCγ activity inhibitor containing, as an active ingredient, a compound selected from the group consisting of baicalin, baicalein, luteonin, apigenin, apigenin glucoside, and salts thereof. These PKCγ activity inhibitors can be used to improve any symptoms caused by abnormal PKCγ activity.

[0031] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples.

[0032] [Test Example 1] (Memory Impairment Model Mouse) DGKβ, one of the subtypes of diacylglycerol kinase (DGK), of which 10 subtypes have been discovered in mammals, is particularly abundant in the hippocampus, cerebral cortex, and striatum of the brain, and has been found by the present inventors to rapidly increase during the development of neural networks, and to be expressed neuron-specifically and promote neurite outgrowth. Mice in which this DGKβ was knocked out (DGKβKO mice) were generated as a memory impairment model. Note that this memory impairment model mouse is not a mouse showing intracerebral accumulation of Aβ, a mouse model of irreversible neurodegenerative disease, a mouse exposed to general anesthesia such as isoflurane, or a mouse model of cerebral infarction.

[0033] The PKCγ inhibitor scutellarin was orally administered to memory impairment model mice at a dose of 100 mg / mouse for 10 days. Separately, normal mice were prepared and similarly administered the PKCγ inhibitor scutellarin orally at a dose of 100 mg / mouse for 10 days.

[0034] (Memory impairment evaluation system) A Y-maze apparatus was used. The Y-maze is an apparatus with three arms of the same size connected radially at 120° intervals, and is used in the spontaneous alternation behavior test, which is one of the spatial memory evaluation tests. As an evaluation index of spatial memory, the value obtained by dividing the number of three consecutive entries into different arms by the total number of entries into the arms minus 1, and then multiplying the result by 100 (cross-reaction, alternations) was used. The lower the alternations, the higher the degree of memory impairment.

[0035] (Results) The results are shown in Figure 1. In the figure, WT indicates the results for normal mice, KO indicates the results for memory-impaired model mice, - indicates the results without scutellarin administration, and + indicates the results with scutellarin administration. Furthermore, numbers in formats such as "WT-: 5" represent the number of mice (the same applies to subsequent figures). As shown in Figure 1, the alternation values ​​were significantly lower in the memory-impaired mouse (KO) group not administered scutellarin (-), revealing the occurrence of memory impairment. Furthermore, administration of scutellarin (+) significantly increased the alternation values, demonstrating that the memory impairment in the memory-impaired mouse (KO) group was improved to a level close to that of normal mice (WT).

[0036] The cerebral cortex and hippocampus of the mice administered scutellarin were subjected to Western blotting to evaluate PKC activation, and the results are shown in Figure 2 (cerebral cortex) and Figure 3 (hippocampus).

[0037] As shown in Figures 2 and 3, abnormal PKCγ activity was observed in the cerebral cortex and hippocampus of the memory impairment model mice (KO) group without scutellarin administration (-), whereas PKCγ activity was found to have improved to normal levels in the memory impairment model mice (KO) group with scutellarin administration (+).

[0038] [Test Example 2] The inhibitory effect of various flavonoids on PKCγ activity was tested. Specifically, scutellarin (Scu), baicalin (Bai), luteolin (Lut), and apigenin (Api) were used as flavonoids. A plasmid encoding GFP-PKCγ was introduced into COS7 cells by electroporation, and the cells were cultured for 48 hours to express GFP-PKCγ. After treating the cells with TPA (12-O-Tetradecanoylphorbol-13-acetate, a PKCγ activator) and each flavonoid, the cells were disrupted and the proteins were subjected to SDS-PAGE. Subsequently, Western blotting was performed on PKCγ and phosphorylated PKCγ (activated form).

[0039] The electrophoresis results (n=2) are shown in Figure 4. As shown in Figure 4, not only scutellarin (Scu) but also baicalin (Bai), luteolin (Lut), and apigenin (Api) were found to have inhibitory effects on PKCγ activity. From these results, it can be reasonably inferred that similar memory impairment amelioration effects would be observed when baicalin (Bai), luteolin (Lut), and apigenin (Api) were administered to the memory impairment model mice of Test Example 1.

Claims

1. A memory impairment improving agent containing a PKCγ activity inhibitor as an active ingredient.

2. The memory impairment improving agent according to claim 1, wherein the PKCγ activity inhibitor is a flavonoid selected from the group consisting of scutellarin, baicalin, baicalein, luteonin, apigenin, apigenin glucoside, and salts thereof.

3. The memory impairment improving agent according to claim 1, which is used to improve memory impairment not caused by accumulation of amyloid beta.

4. The memory impairment improving agent according to claim 1, which is used to improve memory impairment not caused by exposure to general anesthesia.

5. The memory impairment improving agent according to claim 1, which is used to improve memory impairment not caused by cerebral infarction.

6. A food comprising the memory impairment improving agent according to claim 1.

Images