Agent for preventing or improving diabetic neuropathy

Abstract

To provide a preventive or ameliorating agent for diabetic neuropathy, which improves symptoms of diabetic neuropathy.SOLUTION: Provided is a prophylactic or ameliorating agent for diabetic neuropathy comprising a fig or an extract thereof as an active ingredient.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an agent for preventing or ameliorating diabetic neuropathy. [Background technology]

[0002] The number of diabetes patients in Japan is increasing with changes in lifestyle and social environment. Once diabetes develops, it is difficult to cure, and if left untreated, it can lead to complications such as retinopathy, nephropathy, and neuropathy. Diabetic neuropathy is the most common complication of diabetes, and manifests as autonomic neuropathy, such as repeated constipation and diarrhea, erectile dysfunction, dizziness, and abnormal sweating, and sensory neuropathy, which presents numbness and abnormal sensations. These symptoms are thought to be the result of abnormalities in various parts of the body caused by the loss of peripheral nerve fibers and decreased nerve function. In many cases, symptoms begin with subjective symptoms such as numbness and pain in the feet, and gradually spread to the central nerves. If appropriate treatment is not given, the loss of sensory nerve fibers makes it impossible to feel pain or heat. As a result, foot ulcers form, and if left untreated, gangrene develops, and in the worst case, the patient may have to have their lower limbs amputated, significantly reducing the patient's quality of life (QOL).

[0003] The cause of diabetic neuropathy is said to be metabolic abnormalities in peripheral nerve tissue caused by persistent hyperglycemia, and reduced blood flow due to thickening and stenosis of small blood vessels. Risk factors involved in the onset and progression of diabetic neuropathy include poor glycemic control, duration of diabetes, hypertension, dyslipidemia, smoking, and alcohol consumption. Of these, the most important factor is poor glycemic control, and it is said that neuropathy occurs frequently in cases of poor glycemic control. However, even if poor glycemic control is a risk factor for onset and progression, it has not been necessarily established whether strict glycemic control can suppress onset and progression.

[0004] To date, there is no established cure for diabetic neuropathy, and the main treatments are symptomatic treatment to alleviate pain symptoms and treatment to slow the progression of neuropathy, such as with aldose reductase inhibitors (e.g., Epalrestat).

[0005] On the other hand, the fruit of figs (Ficus carica L.) is widely used as food, and the dried fruit and leaves are called figs and fig leaves, respectively, and are used as herbal medicines. It has also been reported that fig extracts have a fat decomposition promoting effect (Patent Document 1) and an anti-influenza virus effect (Patent Document 2), and that fig leaf extracts have a blood sugar lowering effect (Patent Document 3).

[0006] However, it is not known at all that figs are effective in preventing or improving diabetic neuropathy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2009-242432 A [Patent Document 2] JP 2004-059463 A [Patent Document 3] JP 2009-108025 A Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention relates to providing an agent for preventing or ameliorating diabetic neuropathy, which ameliorates the symptoms of diabetic neuropathy. [Means for solving the problem]

[0009] The inventors have searched for natural materials and found that fig fruit extract has the effect of suppressing nerve disorders such as decreased nerve conduction velocity, decreased sensory function, decreased balance function, and myelin disorder caused by diabetes.

[0010] That is, the present invention relates to the following 1) and 2). 1) An agent for preventing or improving diabetic neuropathy, comprising fig or its extract as an active ingredient. 2) A food for preventing or improving diabetic neuropathy, containing fig extract as an active ingredient. Effect of the Invention

[0011] According to the present invention, it is possible to provide a medicine, a quasi-drug, a food, or a supplement for preventing or improving diabetic neuropathy. According to the present invention, it is possible to promote the recovery of nerve function damaged by diabetes, and therefore it is possible to provide a new means for improving QOL. [Brief description of the drawings]

[0012] [Figure 1] The effect of fig extract intake on improving decreased nerve conduction velocity. [Diagram 2] The effect of fig extract intake on improving sensory dysfunction. [Diagram 3] The effect of fig extract intake on improving impaired balance function. [Figure 4] The effect of fig extract intake on improving thinning of myelin diameter. [Diagram 5] The effect of fig extract intake on improving decreased nerve conduction velocity. [Figure 6] The effect of fig extract intake on improving impaired balance function. [Figure 7] Participant recruitment and selection process [Figure 8] Effect of fig consumption on blood sugar levels [Figure 9] Effect of fig intake on nerve function (nerve conduction study) [Figure 10] Effect of fig intake on sensory function (plantar sensation test) [Figure 11] Effects of fig intake on neurological and sensory functions (perception threshold test) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In the present invention, "fig" refers to Ficus carica L. of the family Mulberry. The part of the fig used for extraction may be, for example, the stem, shoot, bud, wood, bark, lichen, root, rhizome, corm, tuber, seed, fruit, etc. or a combination thereof, but it is preferred to use the fruit, and more preferably to use dried fruit.

[0014] The method for producing the fig extract used in the present invention is not particularly limited, and the extract can be obtained by extracting the above-mentioned plant parts by a known method. In the present invention, an extract produced by a solvent extraction method using various extraction solvents is preferably used.

[0015] The solvent for extraction may be either a polar solvent or a non-polar solvent. Specific examples of the solvent include water; alcohols such as methanol, ethanol, propanol, and butanol; polyhydric alcohols such as propylene glycol and butylene glycol; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate; linear and cyclic ethers such as tetrahydrofuran and diethyl ether; polyethers such as polyethylene glycol; hydrocarbons such as squalane, hexane, cyclohexane, and petroleum ether; aromatic hydrocarbons such as toluene; halogenated hydrocarbons such as dichloromethane, chloroform, and dichloroethane; and supercritical carbon dioxide; pyridines; organic solvents such as fats and oils, waxes, and other oils; and mixtures thereof. Suitable solvents include water, alcohols, and alcohol-water mixtures, with alcohol-water mixtures being more preferred. Ethanol is preferred as the alcohol. Furthermore, the alcohol-water mixture can be used in any ratio, but is preferably a mixture with an alcohol ratio of 50 to 99.9% (v / v % at 20°C), more preferably a mixture with an alcohol ratio of 75 to 99.8%, and even more preferably a mixture with an alcohol ratio of 90 to 99.7%.

[0016] The amount of the extraction solvent used is not particularly limited as long as sufficient extraction efficiency is obtained, but for example, it is preferably 2 to 60 times by mass, more preferably 3 to 30 times by mass, and most preferably 5 to 15 times by mass relative to the dried fig material. The extraction conditions are not particularly limited as long as sufficient extraction efficiency is obtained. The extraction temperature is preferably 0°C or higher and below the boiling point of the solvent used, more preferably room temperature, but if the extraction temperature is higher, extraction can be completed in a shorter time. The extraction period (time) is preferably 10 minutes to 1 day when the extraction is performed by heating to 40°C or higher, for example, 12 to 24 hours at 40 to 50°C, 2 to 12 hours at 50 to 60°C, and 10 minutes to 2 hours at 60 to 70°C. In addition, when the extraction is performed at 40°C or lower, it is preferably 1 day to 30 days, more preferably 7 days to 21 days. For example, 1 to 7 days at 40 to 30°C, 7 to 21 days at 30 to 20°C, and 21 to 30 days at 20 to 10°C are included. More preferably, it is 7 to 14 days at room temperature.

[0017] The extraction means is not particularly limited, but for example, conventional means such as solid-liquid extraction, liquid-liquid extraction, maceration, decoction, percolation, reflux extraction, pressurized and heated extraction, distillation, and supercritical extraction can be used.

[0018] The fig extract of the present invention may be a crude product, so long as it meets, for example, food and pharmaceutical acceptable standards and exerts the effects of the present invention. If necessary, it may be subjected to treatments such as removal of inactive contaminants, deodorization, decolorization, etc., by known techniques such as liquid-liquid distribution, solid-liquid distribution, activated carbon treatment, ion exchange resin treatment, etc. Furthermore, the concentration or proportion of a certain component (fraction) may be increased by appropriately combining known separation and purification methods (for example, removing a fraction having a molecular weight of 10 kD or more by ultrafiltration membrane separation). Purification means include organic solvent precipitation, centrifugation, ultrafiltration membrane separation, high performance liquid chromatography, column chromatography, etc.

[0019] In the present invention, the above extract can be used as it is, or can be used after diluting, concentrating or freeze-drying the extract and preparing it into a powder or paste. It can also be freeze-dried and dissolved or diluted with a solvent usually used in extraction, such as water, ethanol, propylene glycol, a water-ethanol mixture, a water-propylene glycol mixture, or a water-1,3-butylene glycol mixture, before use. It can also be used after being encapsulated in a vesicle such as a liposome or a microcapsule.

[0020] As shown in the Examples below, when fig extract is added to diabetic neuropathy model animals and raised, neuropathy such as decreased nerve conduction velocity, decreased sensory function, decreased balance function, and myelin disorder is suppressed without lowering blood sugar levels. Therefore, fig or an extract thereof can be an agent for preventing or improving diabetic neuropathy, and can be used to manufacture an agent for preventing or improving diabetic neuropathy. That is, the fig or an extract thereof of the present invention can be used for preventing or improving diabetic neuropathy. Here, the use may be therapeutic or non-therapeutic. "Non-therapeutic" is a concept that does not include medical procedures, i.e., a concept that does not include a method of surgery, treatment, or diagnosis of humans, more specifically, a concept that does not include a method of surgery, treatment, or diagnosis performed on humans by a physician or a person under the instruction of a physician.

[0021] In the present invention, the term "diabetic neuropathy" refers to neuropathy that appears after the onset of diabetes. "Diabetic neuropathy" is divided into distal symmetric polyneuropathy and focal mononeuropathy, and the diabetic neuropathy of the present invention includes both of them. Distal symmetric polyneuropathy is divided into sensory-motor neuropathy and autonomic neuropathy. In sensory-motor neuropathy, a decrease in nerve conduction velocity is observed in nerve conduction tests from the early stage of onset, and sensory abnormalities such as spontaneous pain, numbness, paresthesias, and hypoesthesia appear in the distal lower limbs, as well as motor abnormalities such as muscle weakness, muscle atrophy, and decreased balance function. As the symptoms ascend, symptoms also appear in the distal upper limbs. Eye and facial movements are also impaired. Autonomic nervous system disorders can present a variety of symptoms, including pupillary dysfunction, orthostatic hypotension, cardiac nerve disorders (sudden death, painless myocardial infarction), abnormal sweating, gastrointestinal motility disorders (constipation, diarrhea), bladder dysfunction, and erectile dysfunction. Focal mononeuropathy includes cranial neuropathy (especially external ophthalmoplegia), neuropathy of the trunk and limbs, and diabetic amyotrophy (lumbosacral root plexus neuropathy).

[0022] In the present invention, "improvement" of diabetic neuropathy includes "treatment." "Treatment" refers to alleviating the symptoms of diabetic neuropathy, or preventing or delaying the progression (worsening) of the symptoms. Furthermore, "prevention" of diabetic neuropathy refers to preventing, suppressing or delaying the onset of neuropathy after the onset of diabetes, or reducing the risk of onset of neuropathy.

[0023] The agent for preventing or ameliorating diabetic neuropathy of the present invention can itself be a drug, quasi-drug, or food that exhibits the effect of improving diabetic neuropathy, or can be a material or preparation to be added to these. In addition, the above-mentioned foods (also referred to as "foods for preventing or improving diabetic neuropathy") include not only general foods and beverages, but also foods labeled as such, functional foods, foods for patients, foods for specified health uses, foods with functional claims, and supplements, as necessary.

[0024] The above-mentioned medicines (including quasi-drugs) containing the fig or its extract of the present invention can be administered in any dosage form, but oral administration is preferred. When administering, the active ingredient can be mixed with a solid or liquid pharmaceutical non-toxic carrier suitable for administration methods such as oral administration, rectal administration, and injection, and administered in the form of a conventional pharmaceutical preparation.

[0025] Examples of such preparations include solid preparations such as tablets, granules, powders, and capsules, liquid preparations such as solutions, suspensions, and emulsions, and freeze-dried preparations. These preparations can be prepared by conventional means for preparations by appropriately adding conventional additives such as stabilizers, wetting agents, emulsifiers, binders, isotonicity agents, and excipients.

[0026] The food containing the fig or its extract of the present invention may take the form of soft drinks, tea drinks, coffee drinks, fruit juice drinks, carbonated drinks, jellies, wafers, biscuits, bread, noodles, sausages, and other foods and nutritional foods, as well as nutritional supplement compositions in the same form as the oral preparations described above (solid preparations such as tablets, capsules, and lozenges). Among these, tablets are preferred. Foods of various forms can be prepared using the fig or an extract thereof of the present invention alone or in appropriate combination with other food ingredients, solvents, softeners, oils, emulsifiers, preservatives, flavorings, stabilizers, colorants, antioxidants, moisturizers, thickeners, etc.

[0027] The content of fig or its extract in the above-mentioned medicines (including quasi-drugs) and foods varies depending on the form of use, but is preferably 0.001 mass% or more, more preferably 0.01 mass% or more, and preferably 10 mass% or less, more preferably 5 mass% or less, and also preferably 0.001 to 10 mass%, more preferably 0.01 to 5 mass%, calculated as a dried substance (for example, a dried substance dried in the sun for 1 to 1.5 weeks).

[0028] The dosage or intake of the above medicines (including quasi-drugs) and foods may vary depending on the condition, body weight, sex, age, or other factors of the subject, but in the case of oral administration or intake, the amount of fig per adult (body weight 60 kg) per day, calculated on a dry matter basis, is preferably 10 g or more, more preferably 30 g or more, and preferably 50 g or less, more preferably 45 g or less, and preferably 10 to 50 g, more preferably 30 to 45 g. The amount of fig extract per day, calculated on a dry matter basis, is preferably 1 g or more, more preferably 4 g or more, and preferably 30 g or less, more preferably 10 g or less, and preferably 1 to 30 g, more preferably 4 to 10 g.

[0029] Subjects to whom the diabetic neuropathy prophylactic or ameliorating agent of the present invention is ingested or administered include diabetic patients who have developed the above-mentioned sensory / motor neuropathy, autonomic neuropathy, or focal mononeuropathy, or diabetic patients or people with high blood sugar levels, and who wish to prevent, suppress, or delay the onset of such neuropathy.

[0030] In relation to the above-described embodiment, the present invention further discloses the following aspects. <1> An agent for preventing or improving diabetic neuropathy, comprising fig or an extract thereof as an active ingredient. <2> A food for preventing or improving diabetic neuropathy, containing fig extract as an active ingredient.

[0031] <3> 2. Use of fig or an extract thereof for the manufacture of an agent for preventing or improving diabetic neuropathy. <4> Use of a fig extract for producing a food for preventing or improving diabetic neuropathy.

[0032] <5> 1. Fig or an extract thereof for preventing or ameliorating diabetic neuropathy. <6> Non-therapeutic use of fig or an extract thereof for preventing or ameliorating diabetic neuropathy.

[0033] <7> A method for preventing or ameliorating diabetic neuropathy comprising ingesting or administering fig or an extract thereof to a subject in need thereof.

[0034] <8> <1> ~ <7> In the above, the fig is preferably a fig fruit. <9> <1> ~ <7> In the above, the extract is preferably an alcohol-water mixed solution, preferably an alcohol-water mixed solution extract of 50 to 99.9 V / V%. <10> <1> ~ <7> in which the diabetic neuropathy is one or more selected from sensory abnormalities such as spontaneous pain, numbness, paresthesias, and hypoesthesia in the extremities; motor function abnormalities such as muscle weakness, muscle atrophy, and impaired balance; eye movement or facial movement disorders; pupillary dysfunction; orthostatic hypotension; cardiac nerve disorders (sudden death, painless myocardial infarction); sweating disorders; gastrointestinal motility disorders (constipation, diarrhea); bladder dysfunction; erectile dysfunction; cranial nerve disorders (especially external ophthalmoplegia); trunk and limb neuropathy; and diabetic muscular atrophy (lumbosacral root plexus neuropathy). <11> <1> ~ <4> In any of the agents or foods, the content of fig or an extract thereof in the pharmaceutical (including quasi-drug) or food is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and preferably 10% by mass or less, more preferably 5% by mass or less, or is 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, calculated on a dry matter basis. <12> <1> ~ <11> In the above, the amount of fig or its extract, or the medicine (including quasi-drug) or food containing the same, administered or ingested orally, is preferably 10 g or more, more preferably 30 g or more, and preferably 50 g or less, more preferably 45 g or less, and preferably 10 to 50 g, more preferably 30 to 45 g, of fig per day per adult (body weight 60 kg), calculated on a dry matter basis. Also, the amount of fig extract is preferably 1 g or more, more preferably 4 g or more, and preferably 30 g or less, more preferably 10 g or less, and preferably 1 to 30 g, more preferably 4 to 10 g, calculated on a dry matter basis. EXAMPLES

[0035] Preparation Example 1 Preparation of Fig Extract 500g of dried fruit (sun-dried fruit) of fig (Ficus carica L.) of the Mulberry family was cut into 1 / 4 size pieces using scissors, and then 5L of 99.5V / V% (20℃) ethanol was added and the fruit was left to soak at room temperature for 8 days. After that, the extract was separated from the extraction residue by filtration, and the extract was concentrated under reduced pressure. The concentrate was further diluted with ion-exchanged water and then freeze-dried. As a result, 99g of fig extract was obtained.

[0036] Example 1: Effect of fig extract on streptozotocin-induced diabetic neuropathy model 1) Three-week-old C57BL / 6J mice were intraperitoneally administered streptozotocin (150 mg / kg, diluted with citrate buffer pH 4.0) or citrate buffer (pH 4.0), and 4 days after administration, blood was taken from the tail vein and blood glucose levels were measured. Mice with blood glucose levels of 260 mg / dL or higher were selected and divided into groups (solvent-administered control diet group, streptozotocin-administered control diet group, streptozotocin-administered fig extract diet group, streptozotocin-administered epalrestat (0.04%) diet group; n=8-10 per group) to avoid large differences in blood glucose levels, and were raised on each diet. The composition of the diets is shown in Table 1. The "fig extract" used was the extract prepared in Production Example 1.

[0037] [Table 1]

[0038] 2) One and three weeks after the dietary load, blood was collected from the tail and blood glucose levels were measured at regular intervals.

[0039] 3) Balance function was measured by a beam test 5 weeks after the food loading. In the beam test, a convex bar was placed 100 cm above the ground and parallel to the ground, and the mouse was made to walk from the start point to the goal point, and the time required was recorded. The total length of the passage was 50 cm, and the width was designed to be 11 mm at the start point and 6 mm at the goal point. Measurements were taken twice and the average was calculated. The maximum time was set at 20 seconds, and if the mouse was unable to reach the goal, it was recorded as 20 seconds.

[0040] 4) After 6 weeks of feeding, sensory function was measured by the Von Frey test. In the Von Frey test, a 1.4g filament was pressed against the mouse's hind paw and the escape reaction was observed. Ten trials were performed and the frequency of escape reactions was recorded.

[0041] 5) Five weeks after the dietary loading, the motor nerve conduction velocity (MNCV) of the tibial nerve was measured under anesthesia using an electromyography-evoked potential tester (MEB-9402MB).

[0042] 6) The diameter of myelin in the nerve was evaluated by calculating the g-ratio. After 7 weeks of dietary loading, the peroneal nerve was pre-fixed with 2.5% glutaraldehyde and post-fixed with 1% osmic acid. After embedding in Epon resin, semi-thin (1.5 μm) sections were prepared and stained with 0.5% toluidine blue. Statistics were performed using the Kruskal-Wallis test for Von Frey tests and the Dunnett test for other tests. The significance level was set at P<0.05.

[0043] 7) Results a) Blood glucose levels one week after dietary loading are shown in Table 2. Streptozotocin administration caused a significant increase in blood glucose levels. Furthermore, after 3 weeks of dietary loading, blood glucose levels were 600 mg / dL or higher in all streptozotocin-administered rats. However, no change in blood glucose levels was observed after the ingestion of epalrestat or fig extract diets.

[0044] [Table 2]

[0045] b) Streptozotocin administration significantly decreased the nerve conduction velocity of the tibial nerve, a motor nerve. On the other hand, the decrease in nerve conduction velocity caused by streptozotocin administration was significantly improved by the ingestion of epalrestat and fig extract diets (Figure 1). c) In the Von Frey test, a decrease in sensory function due to streptozotocin administration was observed. On the other hand, the decrease in sensory function due to streptozotocin administration was significantly improved by the ingestion of epalrestat and fig extract diets (Figure 2). d) In the beam test, a decrease in balance function due to streptozotocin administration was observed. On the other hand, the intake of the fig extract diet significantly improved the decrease in balance function due to streptozotocin administration (Figure 3). e) Histological analysis showed that streptozotocin administration caused a decrease in myelin diameter. On the other hand, the intake of epalrestat and fig extract diet significantly improved the decrease in myelin diameter caused by streptozotocin administration (Figure 4).

[0046] Example 2 Effect of fig extract on diabetic neuropathy model in db / db mice 1) Five-week-old db / db mice (which exhibit hyperphagia and hyperglycemia due to a mutation in the leptin receptor and are used as a type II diabetes model mouse) were divided into three groups (n=10 per group) so that blood glucose levels were equal: db / db-control diet group, db / db-epalrestat diet group, and db / db-fig extract diet group, and were raised on each diet (the composition of the diet was the same as in Table 1 above). As a control group, db / m mice (heterozygotes of db / db mice) were raised on the control diet (db / m-control diet group).

[0047] 2) Five weeks after the dietary intake, blood was collected from the tail and blood glucose levels were measured at regular intervals.

[0048] 3) After 4 weeks of food loading, balance function was measured by a beam test. In the beam test, a convex bar was placed 100 cm above the ground and parallel to the ground, and the mouse was made to walk from the start point to the goal point, and the time required was recorded. The total length of the passage was 50 cm, and the width was designed to be 11 mm at the start point and 6 mm at the goal point. Measurements were taken twice and the average was calculated. The maximum time was set to 100 seconds, and if the mouse was unable to reach the goal, it was recorded as 100 seconds.

[0049] 4) After 4 weeks of dietary loading, the motor nerve conduction velocity (MNCV) of the tibial nerve was measured under anesthesia using an electromyography-evoked potential tester (MEB-9402MB). Statistics were performed using the Dunnett test, with a significance level of P<0.05.

[0050] 5) Results a) Blood glucose levels after 5 weeks of dietary loading are shown in Table 3. Compared to the db / db-control diet group, no changes in blood glucose levels were observed with the epalrestat diet or fig extract intake.

[0051] [Table 3]

[0052] b) Nerve conduction velocity was significantly decreased in the db / db-control group compared to the db / m-control group, whereas it was significantly improved in the fig extract group compared to the db / db-control group (Figure 5). c) In addition, the beam test showed a decline in balance function in the db / db-control diet group compared to the db / m-control diet group. On the other hand, the balance function was significantly improved in the epalrestat diet and fig extract diet groups compared to the db / db-control diet group (Figure 6).

[0053] Example 3: The effect of figs on patients with diabetic neuropathy (1) Test Overview To investigate the effectiveness of figs on diabetic neuropathy, subjects with diabetic neuropathy were asked to consume either dried mango (control group) or dried fig (fig group) daily for two months. The evaluation items in this study were nerve function and sensory function related to the diagnosis of diabetic neuropathy, subjective symptoms, and evaluation by a doctor who regularly treats diabetic neuropathy.

[0054] (2) Target audience To investigate the effectiveness of figs against diabetic neuropathy, patients with diabetic neuropathy were included. The criteria for diabetic neuropathy were set based on the "Diabetic Neuropathy Association Diagnostic Criteria 2002 Revised Edition" described in the Diabetes Treatment Guidelines 2019. Specifically, the patient was asked about their history of diabetes, and if they had been diagnosed with diabetes and had an HbA1c value of 6.0 or higher, they were considered to have "diabetes" and were required items. In addition, the condition items were "neuropathy" if two or more of items 1-3 of the diagnostic criteria shown below were met, or if item 4 was met. Regarding item 2, vibration sense, it was considered to be "applicable" if a decrease was observed in either the medial malleolus or the first toe. In addition, nerve conduction tests were performed on both feet, and if the conduction velocity or amplitude showed abnormal values ​​on both sides, "neuropathy" was considered to be present (the criteria for abnormal values ​​are described for each measurement item). In addition, the following 10 exclusion criteria were set and confirmed at the time of informed consent.

[0055] <Diagnostic criteria for diabetic neuropathy> JPEG0007682014000004.jpg46170

[0056] <Exclusion criteria> JPEG0007682014000005.jpg53170

[0057] (3) Study participant recruitment and selection process The flow of recruiting study participants and selecting subjects is shown in Figure 7. Through recruitment, 80 people aged 30-65 years old who were suspected of having diabetes and diabetic neuropathy and did not fall under the exclusion criteria were recruited. A screening test was conducted on the 80 candidates, and 40 participants who met the diagnostic criteria for diabetic neuropathy were selected. Just before the final measurement, three people in the control group and one person in the fig group withdrew for personal reasons, so the number of participants who completed the final measurement was 17 in the control group and 19 in the fig group.

[0058] (4) Method The study was conducted in an open-label manner. However, participants were not informed of which test product was expected to have activity. Furthermore, the examiners did not know which test product each participant had taken. The subjects were divided into two groups to avoid bias in the following items measured during the screening test (nerve conduction velocity, amplitude, Achilles tendon reflex, vibration sense, HbA1c, fasting blood glucose level, age, and male / female ratio). The study lasted for two months, during which participants were asked to consume approximately 50g of dried mango (Tomizawa Shoten, Philippines) or dried fig (Tomizawa Shoten, Turkey, Smyrna variety) every day. Questionnaires and various measurements were conducted at the start of the study (initial measurement), one month later (intermediate measurement), and two months later (final measurement). The following items were measured in the screening test and main study (initial measurement, intermediary measurement, final measurement).

[0059] <Screening test> Nerve conduction test, Achilles tendon reflex, vibration sense, blood analysis, interview <Main test (initial measurement, intermediate measurement, final measurement)> Nerve conduction test, Achilles tendon reflex, vibration sense, blood analysis, interview, sensory threshold test, plantar sensation test, gait, questionnaire (Achilles tendon reflex, vibration sense, and interview were not performed in the initial measurement, and the values ​​of the screening test were used as the initial measurement results)

[0060] (a) Questionnaire survey At the start of the study, participants were asked whether they had any subjective symptoms of numbness using the questionnaire below, and at the end of the study, those who had symptoms were asked about any changes in symptoms compared to when the study began. The number of people with numbness in each group was as follows: 13 in the control group, 13 in the fig group.

[0061] <Questionnaire regarding subjective symptoms of numbness> JPEG0007682014000006.jpg16170

[0062] (b) Neurological and sensory function evaluation Nerve conduction test Measurements were taken with the subject lying face down using a nerve conduction measuring device (Omron, HDN-1000). The area where the sensor would come into contact was wiped with a special alcohol sheet (prep pad). Special gel was applied to the electrode parts of the device, and the electrodes were placed at the center of the ankle and Achilles tendon, with the sensor part placed on the midline of the gastrocnemius muscle. With the subject relaxed, a weak pulsed current was passed through the body, and nerve conduction velocity and amplitude were measured. The test was performed on both the left and right legs.

[0063] "Achilles tendon reflex" The following measurements were taken by the nurses: The test participants were asked to kneel backwards on a chair, and the Achilles tendon was tapped 10 times or more using a hammer to test the Achilles tendon reflex, to see if the foot would plantar flex. If the reflex was absent, the reflex was measured using the augmentation method. This was done on both the left and right feet. The scores were 1: normal (plantar flexion), 2: weakened (absent with the normal method, plantar flexion with the augmentation method), and 3: absent (absent with the normal method, absent with the augmentation method). The augmentation method is a method of measuring tendon reflexes in a state where tendon reflexes are more likely to occur by having the participant perform an unrelated movement (clasping their right and left hands together and pulling on each other), as tendon reflexes are less likely to occur when the participant is nervous or concentrating their attention on the test area.

[0064] Vibration sense test The following measurements were taken by the nurses: The participants were asked to sit on a chair with their legs extended. A vibration sense test tuning fork (C128) was vibrated and placed on the medial ankle and the tip of the first toe. The participant was asked to report the point at which they no longer felt the vibration, and this was taken as the measurement. The test was performed on both the left and right feet. The scores were 1: normal (sensed for 10 seconds or more) and 2: decreased (sense disappeared in less than 10 seconds).

[0065] "Perception threshold test" Measurements were taken with the participants lying on their backs using a Neurometer (CPT / C; Neurotron). The area where the sensor would come into contact was wiped with a special alcohol sheet, and the sensor was attached to the measurement site (first toe). Starting with a low-intensity electrical stimulus that was imperceptible, the current stimulus was then gradually increased, and the current intensity (perception threshold) at which the participant was able to perceive the stimulus was recorded. Measurements were taken in the following order: 2000 Hz (Aβ fibers: vibration), 250 Hz (Aδ fibers: touch), and 5 Hz (C fibers: pain, temperature, and autonomic nerves). Measurements were taken on both the left and right feet.

[0066] Plantar sensation test With the subject in a seated position, the feet were placed on a plantar sensation evaluation device (Asuka Electric Works, Ltd.), and the minimum threshold at which the vibration of the contactor against the sole of the foot could be sensed was measured. The minimum threshold was measured at a total of four locations, the ball of the big toe and the ball of the little toe of each foot.

[0067] (c) Other "Blood analysis" Blood samples were collected under standard fasting conditions. In other words, participants had dinner by 9 p.m. the previous day, but did not have breakfast before coming to the hospital. In addition, to prevent hypoglycemia, participants were asked not to take any diabetes medication on the morning of the measurement session. There were no restrictions on other medications.

[0068] "Medical interview and doctor's assessment" A doctor who routinely treats diabetic neuropathy interviewed the subjects about their history of diabetes, whether they had any subjective symptoms of sensory abnormalities in the lower limbs, and the appearance of both feet (below the ankles). These were done three times in total: at the screening test, during the midterm measurement, and at the final measurement. Based on the interview and test values ​​(nerve conduction test, Achilles tendon reflex, vibration sense, and perception threshold test), a comparison was made for each participant with the results at the start of the study. The results were judged on a six-point scale: "markedly improved," "improved," "slightly improved," "no change," "slightly worsened," and "worsened."

[0069] (5) Permitted items During the study, participants were allowed to continue using any oral medications they had been taking on a daily basis.

[0070] (6) Statistics The values ​​obtained are shown as mean ± standard error. Between-group comparisons were performed using chi-square tests for questionnaires, doctor's judgments, Achilles tendon reflexes, and vibration sense tests. Details are described for each item. For other items, statistical analysis was performed using a linear mixed model with "group" and "time" as fixed effects and "participant" as random effects. Since the purpose of this study was to examine the presence or absence of an effect of figs, "time" was set to two points, the initial measurement and the final measurement. In addition, when measurements were performed on both the left and right feet or at multiple locations, the location was also analyzed as a random effect. Details are described for each item. When there was an interaction, the change from the "initial measurement" at the "final measurement" was calculated, and between-group comparisons were performed using unpaired t tests. For those who declined the final measurement, the results of the interim measurements for questionnaires, doctor's judgment, Achilles tendon reflex, and vibration sense test were treated as the final measurement results. For items analyzed using linear mixed models, statistics were performed with missing data.

[0071] (7) Results 1)Participant background The background of the participants in this study is shown in Table 4. The test product intake rate was 90% or higher for all participants. The medication status for diabetes mellitus is shown in Table 5.

[0072] [Table 4]

[0073] [Table 5]

[0074] 2) Effect on blood sugar levels Blood analysis was performed to examine the effect of taking each test product on blood glucose levels (Figure 8). Figure 8: Changes in HbA1c and blood glucose levels over time. Graphs show mean ± standard error. Statistical analysis was performed using a linear mixed model with fixed effects of "group" and "time" and random effect of "participant."

[0075] No interaction was observed when comparing the two groups. In addition, for each group, a paired t test was used to compare HbA1c and fasting blood glucose levels at the end of the study with the initial values, but no significant differences were observed. From these results, no effect was observed on blood glucose levels from the intake of each test product.

[0076] 3) Neurological and sensory functions "Achilles tendon reflex" To examine the effect of fig on nerve function, the Achilles tendon reflex was measured (Table 6). At the end of the test, if the score improved from the initial stage in both legs, the test was deemed "effective," and the number and percentage of subjects who "were effective" are shown (Table 6). A significant difference was found between the control group and the fig group in the number of people who responded positively, indicating that consuming figs improves neurological disorders.

[0077] [Table 6]

[0078] Nerve conduction test To investigate the effects of fig on nerve function in detail, nerve conduction studies were performed (Figure 9). Figure 9: The trends in the mean values ​​of nerve conduction velocity (A) and amplitude (B) in both legs are shown. The trends in the mean values ​​of nerve conduction velocity (C) and amplitude (D) in the right leg are also shown. Note that an interaction was observed for the nerve conduction velocity in the right leg, so the change from the initial value at the end of the study is shown (E). The graphs show the mean ± standard error. (A, B) Statistical analysis was performed using a linear mixed model, with fixed effects of "group" and "time" and random effects of "participant" and "measurement site". (C, D) Statistical analysis was performed using a linear mixed model, with fixed effects of "group" and "time" and random effect of "participant". (E) Statistical analysis was performed using a t-test. * p<0.05 vs. control

[0079] No significant change was observed in the amplitude in both legs between the control and fig groups (Figure 9B). On the other hand, the nerve conduction velocity in both legs tended to improve in the fig group compared to the control group (Figure 9A). Therefore, for reference, the results of conduction velocity and amplitude in the right leg are shown (Figures 9C-E). No significant change was observed in the amplitude in the right leg between the two groups (Figure 9D), but an interaction between "group" and "time" was observed in the conduction velocity (Figure 9C). Therefore, the change in the conduction velocity in the right leg from the initial value at the end of the study was calculated and compared between the groups (Figure 9B). As a result, a significant change was observed in the fig group compared to the control group, indicating that fig intake improves nerve damage.

[0080] Vibration sense test A vibration sense test was conducted to examine the effect of figs on sensory function. At the final measurement, the number and percentage of people who answered "effective" were shown, with the score improving from the initial stage in both feet (Table 7). There was no significant difference in the number of people who answered "effective" between the control group and the fig group, but there was a trend toward improvement due to fig intake.

[0081] [Table 7]

[0082] Plantar sensation test To examine in detail the effect of fig on sensory function, a plantar sensory test was performed (Figure 10). Figure 10: (A) Plantar sensory thresholds were measured at four locations, two on each side (thenar eminence and hypothenar eminence), and the changes over time in the average values ​​are shown. (B) Because an interaction between "time" and "group" was observed, the amount of change from the initial value at the end of the study is shown. The graph shows the mean ± standard error. (A) Statistical analysis was performed using a linear mixed model, with "group" and "time" as fixed effects and "participant" and "measurement site" as random effects. (B) Statistical analysis was performed using a t-test. * p<0.05 vs. control

[0083] As a result, an interaction between "group" and "time course" was observed (Figure 10A). Furthermore, a significant difference was observed in the amount of change from the initial value at the end of the study in the fig group compared to the control group (Figure 10B), demonstrating that fig intake improves sensory function loss due to diabetic neuropathy.

[0084] "Perception threshold test" To investigate the effects of fig on nerve and sensory functions in detail, we conducted a sensory threshold test. Sensory threshold tests quantify sensory thresholds by passing currents of different frequencies through the skin. They are said to be able to evaluate the function of Aδ and C fibers involved in pain sensation, which cannot be detected by nerve conduction tests. Specifically, the sensory thresholds of Aβ fibers can be quantified at 2000 Hz, Aδ fibers at 250 Hz, and C fibers at 5 Hz, and the normal values ​​are 2000 Hz: 155-337 μA, 250 Hz: 58-144 μA, and 5 Hz: 27-87 μA, respectively. The average values ​​at each frequency of the participants in this study were 2000 Hz: 286 ± 20 μA, 250 Hz: 113 ± 9 μA, and 5 Hz: 80 ± 5 μA, respectively, which were close to the upper limit of normal, and it was confirmed that diabetic neuropathy increases the sensory threshold. Therefore, we actually examined the sensory threshold of fig (Figure 11). Figure 11: (A) At each frequency, the perceptual sensory threshold was measured for both the left and right, and the changes over time in the average values ​​were shown. (B) Because an interaction between "time" and "group" was observed at each frequency, the amount of change from the initial value at the end is shown. The graph shows the mean ± standard error. (A) Statistical analysis was performed using a linear mixed model, with "group" and "time" as fixed effects and "participant" and "measurement site" as random effects. (B) Statistical analysis was performed using a t-test. ## p<0.01 vs. "initial" by Bonferroni test, ** p<0.01 vs. control

[0085] As a result, an interaction between "group" and "time" was observed at all frequencies, and furthermore, only in the fig group, the perception threshold was significantly lower at the end compared to the initial value (Figure 11A). Furthermore, the amount of change from the initial value at the end also tended to be lower in the fig group compared to the control group at each frequency, and a significant difference was observed at 250 Hz (Figure 11B). These results demonstrate that fig intake improves the decline in nerve and sensory function caused by diabetic neuropathy.

[0086] 4) Overall assessment and subjective symptoms "Doctor's Judgment" A doctor who routinely treats diabetic neuropathy interviewed participants (at screening, mid-point, and end), and compared the interview and test values ​​(nerve conduction test, Achilles tendon reflex, vibration sense, and perception threshold test) with those at the start of the study for each participant. Results were judged on a six-point scale: "markedly improved," "improved," "slightly improved," "unchanged," "slightly worsened," and "worsened." A score of "slightly improved" or better was considered "effective," and a chi-square test was performed. In the fig intake group, 80% of participants were judged to have "slight improvement" or higher, a significant difference was observed compared to the control group (Table 8), making it clear that fig intake improves diabetic neuropathy.

[0087] [Table 8]

[0088] "Subjective symptoms" At the start of the study, 26 participants who reported having subjective symptoms of numbness were asked about any changes in symptoms at the end of the study. Evaluation was done on a six-point scale: "markedly improved," "improved," "slightly improved," "unchanged," "slightly worsened," and "worsened." Evaluations of "slightly improved" or higher were considered "effective," and a chi-square test was performed. As a result, in the fig intake group, 85% of participants who had numbness at the start of the study were rated as "slightly improved" or better, showing a significant difference compared to the control group (Table 9). These results demonstrate that fig intake improves the subjective symptoms of numbness caused by diabetic neuropathy.

[0089] [Table 9]

Claims

1. An agent for preventing or improving diabetic neuropathy, comprising an ethanol extract of fig fruit as an active ingredient, wherein the neuropathy is selected from a decrease in nerve conduction velocity, a decrease in sensory function, a decrease in balance function, and myelin disorder.

2. A food for preventing or improving diabetic neuropathy, comprising an ethanol extract of fig fruit as an active ingredient, wherein the neuropathy is selected from a decrease in nerve conduction velocity, a decrease in sensory function, a decrease in balance function, and myelin disorder.

3. An agent as described in claim 1 or a food as described in claim 2, which suppresses nerve damage without lowering blood sugar levels.

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