JP2007291133A - Therapeutic agent containing hyaluronic acid oligosaccharide as active ingredient - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide therapeutic agents such as a therapeutic agent for hypertrophic arthritis or traumatic arthritis. <P>SOLUTION: The therapeutic agent for hypertrophic arthritis or traumatic arthritis, autoimmune disease therapeutic agent, therapeutic agent for brain disease or degenerative disease, ischemic heart disease therapeutic agent, neurologic disease therapeutic agent, heart disease therapeutic agent, inflammation therapeutic agent, infectious disease therapeutic agent against bacterial infections or viral infections, or diabetes therapeutic agent contains a hyaluronic acid oligosaccharide comprising 2 to 20 saccharides as an active ingredient. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a therapeutic agent for osteoarthritis or traumatic arthritis, a therapeutic agent for autoimmune disease, a therapeutic agent for brain disease or brain degenerative disease, a therapeutic agent for ischemic disease, comprising a hyaluronic acid oligosaccharide having 2 to 20 sugars as an active ingredient. The present invention relates to an agent, a therapeutic agent for neurological diseases, a therapeutic agent for heart diseases, a therapeutic agent for inflammation, a therapeutic agent for infection against bacterial or viral infection, and a therapeutic agent for diabetes.

  Hyaluronic acid is a long-chain polysaccharide composed of disaccharide repeating units of D-glucuronic acid and N-acetyl-D-glucosamine, while oligosaccharides are also known. Hyaluronic acid is produced by extraction from biological tissues such as chicken crowns, corpses, skin, joint fluid, or fermentation methods using bacteria belonging to the genus Streptococcus, and has no toxicological or immunological effects. It is used as a cosmetic, and for example, treatment of arthritis by intraarticular injection of hyaluronic acid is well known.

  On the other hand, stress proteins are known as proteins that protect against damage caused by various stress reactions. Stress proteins are proteins that were originally recognized because they are induced when heat treatment is applied to cells, but they are also present in cells that do not receive stress. Known stress proteins include HSP70 family such as HSP70, HSP72 and HSP73; HSP90 family; HSP20 family such as HSP20, HSP27 and HSP28; HSP40 family such as HSP40 and HSP47, and proteins such as ubiquitin and histone H2B. Among them, HSP70 family proteins are heat shock proteins having a molecular weight of about 70,000 and homologues thereof, and are highly conserved proteins from E. coli to humans.

  These stress proteins, especially HSP70 family proteins, are factors that cause environmental stress such as heat shock, hydrogen peroxide, heavy metals, amino acid analogs, and glucose starvation; fever, inflammation, ischemia, viral infection, metabolic diseases, cardiac hypertrophy Suppresses protein degeneration and structural changes caused by stress factors such as oxidative stress, cell and tissue damage, pathological conditions caused by oncogenes and carcinogens, and the production of abnormal proteins. It is thought that cell damage (cell damage, cell degeneration, etc.), cell death, etc. are prevented by the action of regenerating into the protein. For example, neuronal cells undergo metabolic stress due to cerebral ischemia, express (synthesize) stress proteins, prevent neuronal necrosis, induce resistance to neurons against the same stress, heat shock proteins It is known that (HSP) is expressed on the cell surface as cells become cancerous and reacts with specific T cells to establish tumor immunity that leads to immunological rejection of the tumor. Stress protein has been suggested to be associated with many stress proteins such as autoimmune disease, brain degenerative disease, ischemia, hypertrophy, inflammation, bacterial infection, viral infection, Alzheimer's disease, diabetes, Kawasaki It is also expected to be applied to diseases, schizophrenia, and the like, and to be expected to be effective in cancer cell death (Cell., 17 (1979) p241-254, Ann. Rev. Biochem., 55 (1986). ) p1151-1191, J. Cell. Biol., 117 (1992) p1151-1159, Exp. Cell. Res., 195 (1991) p338-344, Exp. Cell. Res., 217 (1995) p15-21, Acta. Neuropathol., 77 (1988) p128-135, Journal of Cerebra Blood Flow and Metabolism, 13 (1993) p781-788, Clin. Invest., 93 (1994) p759-767, Stress Protein "Basic and Clinical" 1994 Published by Chugai Medical, Inc.).

  The present invention relates to a therapeutic agent for osteoarthritis or traumatic arthritis, a therapeutic agent for autoimmune diseases, a therapeutic agent for brain diseases or brain degenerative diseases, a therapeutic agent for ischemic diseases, a therapeutic agent for neurological diseases, a therapeutic agent for heart diseases, a therapeutic agent for inflammation. The present invention provides an agent, a therapeutic agent for infection against bacterial or viral infection, and a therapeutic agent for diabetes. More specifically, the present invention provides a drug that can be applied to the above diseases by suppressing cell damage and cell death by enhancing the expression of stress proteins without adversely affecting the living body.

  The present invention relates to a therapeutic agent for osteoarthritis or traumatic arthritis, a therapeutic agent for autoimmune disease, a therapeutic agent for brain disease or brain degenerative disease, a therapeutic agent for ischemic disease, comprising a hyaluronic acid oligosaccharide having 2 to 20 sugars as an active ingredient. An agent, a therapeutic agent for neurological diseases, a therapeutic agent for heart diseases, a therapeutic agent for inflammation, a therapeutic agent for infection against bacterial or viral infection, or a therapeutic agent for diabetes.

  Since the present invention comprises 2 to 20 sugar hyaluronic acid oligosaccharides as an active ingredient, there is an advantage that it can be easily mass-produced relatively inexpensively. In addition, hyaluronic acid is expected to be applied to various diseases as a therapeutic agent with extremely few side effects because it has almost no toxicity and antigenicity and enhances the therapeutic action and disease prevention action that the body originally has. It is expected to be useful as a preventive for these diseases. In addition, conventional high molecular weight hyaluronic acid (for example, a weight average molecular weight range of about 800,000 to 2,300,000) can be used because of its physical properties. That is, hyaluronic acid oligosaccharides have the advantage that the target therapeutic area is wider than conventional high molecular weight hyaluronic acid.

  Furthermore, by using hyaluronic acid oligosaccharide mixed with high molecular weight hyaluronic acid, the hyaluronic acid oligosaccharide itself has a pharmacological action (for example, stress protein expression enhancing action) and high molecular weight hyaluronic acid. An excellent therapeutic effect can be obtained by both action (for example, signal transmission of various cells via hyaluronic acid receptor) and the protective effect of tissues or cells due to physical properties.

  The hyaluronic acid used in the present invention is basically a disaccharide or more containing at least one disaccharide unit in which the 1-position of β-D-glucuronic acid and the 3-position of β-D-N-acetylglucosamine are bonded. And basically composed of β-D-glucuronic acid and β-DN-acetylglucosamine, these elements are bound to one or more disaccharide units bound together. Sugars may be used, and derivatives thereof such as those having a hydrolyzable protecting group such as an acyl group may also be used. The sugar may be an unsaturated sugar, and examples of the unsaturated sugar include non-reducing terminal sugars, usually those in which the 4- and 5-position carbons of glucuronic acid are unsaturated. As the hyaluronic acid used in the present invention, specifically, those extracted from natural products such as animals, those obtained by culturing microorganisms, and those synthesized chemically or enzymatically are used. be able to. For example, it can be obtained by known extraction and purification methods from biological tissues such as chicken crown, corpse, skin, and joint fluid. It can also be produced by a fermentation method using Streptococcus bacteria or the like.

  In the present invention, 2 to 20 sugar hyaluronic acid oligosaccharides can be used. Preferably, a hyaluronic acid oligosaccharide having 10 sugars or less is mentioned, and more preferably a disaccharide hyaluronic acid can be mentioned.

  Specifically, the 2-20 saccharide hyaluronic acid oligosaccharide used in the therapeutic agent of the present invention is specifically an enzyme decomposition method, an alkali decomposition method, a heat treatment method, an ultrasonic treatment method (Biochem., 33 (1994) p6503- 6507) and the like, and a method of reducing hyaluronic acid by a known method, a method of chemically or enzymatically synthesizing (Glycoconjugate J., (1993) p435-439, WO93 / 20827) and the like. For example, as an enzymatic degradation method, hyaluronic acid degrading enzymes (hyaluronidase (derived from testicles), hyaluronidase (derived from Streptomyces), hyaluronidase SD, etc.), chondroitinase AC, chondroitinase ACII, chondroitinase ACIII, chondroitinase ABC, etc. A method of producing hyaluronic acid oligosaccharides by causing an enzyme that degrades hyaluronic acid to act on hyaluronic acid (Shinsei Chemistry Laboratory "Carbohydrate II-Proteoglycan and Glycosaminoglycan", p244-248, published in 1991, Tokyo Chemical Doujin For example).

  As an alkali decomposition method, for example, a base such as about 1N sodium hydroxide is added to a hyaluronic acid solution, heated for several hours to lower the molecular weight, and then neutralized by adding an acid such as hydrochloric acid. And a method for obtaining low molecular weight hyaluronic acid. Hyaluronic acid used in the present invention includes a salt form, and a pharmaceutically acceptable salt thereof can be used as necessary in the preparation. For example, alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt and magnesium salt, amine salts such as tri (n-butyl) amine salt, triethylamine salt, pyridine salt and amino acid salt Can do.

The therapeutic agent of the present invention can be used without any particular limitation, such as hyaluronic acid oligosaccharides alone or combinations of hyaluronic acids of various molecular weights.
The therapeutic agent of the present invention comprises 2-20 saccharides of hyaluronic acid oligosaccharide (hereinafter also referred to as hyaluronic acid oligosaccharide) as an active ingredient, and an effective amount thereof is administered to mammals including humans so that the living body It is a drug that can treat the above-mentioned diseases by enhancing or inducing the expression of stress proteins without adversely affecting the expression. This drug is administered to mammals including humans suffering from diseases caused by, for example, cell damage (eg, cell damage, cell degeneration) or cell death caused by stress or other reasons By enhancing the expression of or inducing the expression, cell damage or cell death can be suppressed and the animal can be treated.

  The therapeutic agent of the present invention is a disease caused by cell damage or cell death, and many diseases in which a protective action by a stress protein is suggested, such as heart disease (myocardial infarction, etc.), tubular disorder, cardiovascular disease, Ischemic disease caused by stenosis or ischemia such as brain disease (stroke, etc.), neurological disease; AIDS, thymocyte damage caused by administration of immunosuppressive drugs or anticancer drugs, decrease in peripheral T cells, immunodeficiency Immune related diseases such as hepatitis, inflammation such as hepatitis, ulcerative colitis, trauma, bacterial infection, viral infection, Alzheimer's disease, diabetes, hypertrophy, Kawasaki disease, schizophrenia, fever, metabolic disease, cancer, etc. The effect is expected.

  The therapeutic agent of the present invention comprises hyaluronic acid oligosaccharide or a salt thereof administered orally or parenterally as it is or together with a carrier, excipient, or other additives as necessary (intra-articular administration, intravenous administration, It can be formulated into any dosage form as a pharmaceutical for intramuscular and subcutaneous administration (injection), enteral administration, transdermal administration, etc., and administered to patients by any administration method Is done.

  Examples of oral preparations include solid preparations such as powders, granules, capsules and tablets; liquid preparations such as syrups, elixirs and emulsions. The powder can be obtained by mixing with excipients such as lactose, starch, crystalline cellulose, calcium lactate, calcium hydrogen phosphate, magnesium aluminate metasilicate, and silicic anhydride. In addition to the above excipients, the granule is optionally combined with a binder such as sucrose, hydroxypropylcellulose, polyvinylpyrrolidone, a binder such as carboxymethylcellulose, carboxymethylcellulose calcium, carboxymethylrose, carboxymethylcellulose calcium, etc. Further, a disintegrant may be added and granulated by wet or dry method. Tablets can be obtained by compressing the powder or granules as they are or by adding a lubricant such as magnesium stearate or talc. The tablet or granule is coated with an enteric base such as hydroxypropylmethylcellulose phthalate or methyl methacrylate copolymer, or coated with ethylcellulose, carnauba wax, hardened oil, etc. can do. A hard capsule can be obtained by filling a hard capsule with the above powder or granule. The soft capsule can be obtained by mixing hyaluronic acid oligosaccharide or a salt thereof with glycerin, polyethylene glycol, sesame oil, olive oil or the like and coating it with a gelatin film. A syrup can be obtained by dissolving a sweetener such as sucrose, sorbitol, glycerin and the like and a hyaluronic acid oligosaccharide or a salt thereof in water. In addition to sweeteners and water, essential oils, ethanol and the like can be added to make elixirs, or gum arabic, tragacanth, polysorbate 80, sodium carboxymethylcellulose and the like can be added to make emulsions or suspensions. Moreover, a corrigent, a coloring agent, a preservative, etc. can be added to these liquid preparations as needed.

  Examples of parenteral preparations include injections, rectal administration agents, pessaries, external preparations for skin, inhalants, aerosols, eye drops and the like. Injections include hyaluronic acid oligosaccharides or salts thereof, pH regulators such as hydrochloric acid, sodium hydroxide, lactic acid, sodium lactate, sodium monohydrogen phosphate, and sodium dihydrogen phosphate; isotonic agents such as sodium chloride and glucose And distilled water for injection, sterile filtered, and then filled into ampoules. Further, mannitol, dextrin, cyclodextrin, gelatin and the like can be added and lyophilized in a vacuum to obtain an injection that can be dissolved at the time of use. Moreover, after adding an emulsifier, such as lecithin, polysorbate 80, polyoxyethylene hydrogenated castor oil, to hyaluronic acid oligosaccharide or its salt, it can also be set as the emulsion for injection emulsified in water.

For rectal administration, add a suppository base such as mono-, di- or triglycerides of cacao fatty acid or polyethylene glycol to hyaluronic acid oligosaccharides or salts thereof, then dissolve by heating, pour into a mold and cool. Alternatively, hyaluronic acid oligosaccharide or a salt thereof can be mixed with polyethylene glycol, soybean oil, etc., and then coated with a gelatin film. The external preparation for skin can be obtained by adding white petrolatum, beeswax, liquid paraffin, polyethylene glycol or the like to hyaluronic acid oligosaccharide or a salt thereof, and heating and kneading as necessary. The tape agent can be obtained by kneading hyaluronic acid oligosaccharide or a salt thereof with a pressure-sensitive adhesive such as rosin or an alkyl acrylate polymer and spreading it on a nonwoven fabric or the like. The inhalant can be obtained by, for example, dissolving or dispersing hyaluronic acid oligosaccharide or a salt thereof in a propellant such as a pharmaceutically acceptable inert gas and filling the pressure-resistant container.
(Administration method) The administration method of the therapeutic agent comprising the hyaluronic acid oligosaccharide of the present invention as an active ingredient is not particularly limited. However, when used for the treatment of heart disease in ischemic disease, intravenous injection is preferred, and neurological disease Intramuscular injection, intravenous injection, subcutaneous injection or intraperitoneal injection is preferable.
(Dosage) The dosage is appropriately determined according to the target disease, patient age, health condition, body weight, etc. Generally, 0.05 to 50 mg / kg is divided once or more once a day. To administer.
(Toxicity) The hyaluronic acid oligosaccharide used in the present invention showed little or no cytotoxicity at doses showing biological activity as a medicine.

Reference Example 1 Preparation of fluorescein-labeled hyaluronic acid Hyaluronic acid sodium salt (weight average molecular weights of 840,000 and 2.3 million molecular weights) and fluorescein amine were obtained by the method described in the literature (Carbohydr. Res., 105 (1982) p69-85). Reaction was carried out to prepare fluorescein-labeled hyaluronic acid, respectively.
Reference Example 2 Preparation of biotinylated hyaluronic acid binding protein (hereinafter, hyaluronic acid binding protein is referred to as HABR). HABR was isolated from bovine nasal cartilage proteoglycan, extracted, purified by affinity chromatography using immobilized hyaluronic acid, and then labeled with biotin.
Reference example 3
The effect of intraarticular administration of hyaluronic acid on a canine cruciate ligament resection (hereinafter referred to as ACLT) model, which is a model of osteoarthritis and traumatic arthritis, was examined.

Eight male beagle dogs (body weight 7-9 kg) 5-8 months old were used. Out of the 8 dogs, 6 legs were subjected to ACLT. The remaining two animals were used as non-operated normal controls without surgery. As test substances, hyaluronic acid sodium salt (weight average molecular weight 840,000) was dissolved in phosphate buffered saline (PBS) to give 10 mg / ml (hereinafter referred to as HA84), and PBS was used as a negative control. Using.

  Administration of the test substance was started from the 5th week after the ACLT, and the test substance was administered once per week for 5 weeks (5 times in total) at the administration concentration, administration liquid amount and administration amount shown in Table 1. In addition, PBS was administered to the forefoot right knee joint of six dogs subjected to ACLT, and HA84 was administered to the left forefoot knee joint. In the fifth administration of HA84, fluorescein-labeled hyaluronic acid described in Reference Example 1 was used instead of hyaluronic acid in order to examine the tissue distribution of hyaluronic acid.

  One week after the final administration, necropsy was performed and the synovium of the knee joint was collected. After fixing the synovium with 4% paraformaldehyde, a paraffin-embedded specimen and a frozen-embedded specimen were prepared. Thin slices were prepared from the paraffin-embedded specimen and stained with hematoxylin-eosin (HE) to count vacuolar degenerated cells in 200 synovial cells.

  In addition, a sliced section is prepared from the frozen embedded specimen, and immunostaining of HSP72 is performed using an anti-HSP72 monoclonal antibody (Amersham) and FITC-labeled anti-mouse IgG (Jackson) as a secondary antibody. Thereafter, the cells were observed with a confocal laser microscope, and HSP72 positive cells in 200 synovial cells were counted.

  Further, a frozen section was prepared from the frozen embedded specimen, and the fluorescence of the fluorescein derived from the fluorescein-labeled hyaluronic acid and the biotinylated HABR and streptavidin-conjugated Texas red (Southern red) described in Reference Example 2 for the same section were used. The fluorescence of Texas Red derived from hyaluronic acid stained with Biotechnology) was observed using a confocal laser microscope, and the localization of both was examined.

  From these results, the appearance rate of vacuolar degenerated cells and the appearance rate of HSP72-positive cells were determined, and Bonferroni statistical analysis was performed using the Yukms statistical library (manufactured by Yukkusu). The results are shown in Table 2.

  In Reference Example 3, vacuolar degenerated cells were observed in the PBS-administered group, but a significant clear decrease was observed in the appearance rate of vacuolar degenerated cells in the HA84-administered group. On the other hand, HSP72-positive cells showed an increase in the appearance rate in the PBS administration group as compared to the non-operated normal control group, but the appearance rate in the HA84 administration group further increased significantly.

  In addition, as a result of the same test using hyaluronic acid having a weight average molecular weight of 2.3 million (hereinafter referred to as HA230) instead of HA84, the appearance rate of vacuolar denatured cells was reduced while being weaker than HA84, and HSP72 positive Increased cell appearance rate. This Reference Example 3 showed that vacuolar degeneration of synoviocytes by ACLT is suppressed by administration of hyaluronic acid. In addition, the appearance rate of HSP72-positive cells was significantly increased by administration of hyaluronic acid. It is known that HSP72 is expressed in cells under stress and has a function of protecting cells from cell damage due to stress. From the above, it was suggested that hyaluronic acid suppresses vacuolar degeneration of cells due to hyaluronic acid enhancing or inducing the expression of stress protein (HSP72 in the case of Reference Example 3).

  In addition, fluorescence derived from fluorescein-labeled hyaluronic acid (weight average molecular weight of the raw material hyaluronic acid 840,000) was observed mainly in a granular form in and around the cells in the tissue. On the other hand, the tissue staining part of hyaluronic acid using biotinylated HABR had a part overlapping this granular part and the other part and did not match. On the other hand, fluorescein-labeled hyaluronic acid having a weight average molecular weight of 2.3 million could be detected only slightly.

  This is because HABR recognizes 10 or more sugars of hyaluronic acid (J. Biol. Chem., 254 (1979) p4624-4630), so that hyaluronic acid taken up into cells undergoes a reduction in molecular weight and is at least 10 It may be present as hyaluronic acid below sugar or other oligosaccharides. This suggests that hyaluronic acid of 10 sugars or less is involved in the enhancement or induction of stress protein (HSP72 in the case of this Reference Example 3).

  In addition, the HA84 administration group was superior to the vacuole degeneration suppression effect and the stress protein (HSP72 in the present Reference Example 3) expression enhancement effect as compared to the HA230 administration group. This is considered to be because HA84, that is, hyaluronic acid having a lower molecular weight, is superior in permeability or retention in the tissue, as shown in the tissue distribution of the fluorescein-labeled hyaluronic acid.

Example 1
The correlation between the effects of hyaluronic acid oligosaccharides on the cytotoxicity and cell death of canine knee joint synovial cells subjected to heat shock and the expression of HSP72 were examined in vitro. Hyaluronic acid unsaturated disaccharide (ΔDi-HA (sodium salt) of unsaturated chondrodisaccharide kit (C kit): 2-acetamido-2-deoxy-3-O- (β-D-gluco -4-enopyranosyluronic acid) -D-glucose (manufactured and sold by Seikagaku Corporation) and two negative controls.

  Canine knee joint synovial cells are collected, seeded, and medium supplemented with serum, L-glutamic acid, penicillin, streptomycin in Dulbecco's modified Eagle medium (DMEM) until nearly subconfluent. Each of the above test substances was added to the culture. Hyaluronic acid (oligosaccharide) added group was added so that the oligosaccharide concentration in the medium was 1.0 mg / ml (Group 3) and 3.0 mg / ml (Group 4), respectively, and negative No control was added. One group of negative controls was incubated at 37 ° C. for 3 hours (Group 1), and another group of negative controls (Group 2) and the hyaluronic acid-added group were incubated at 45 ° C. for 1 hour after heat stress. The mixture was further incubated at 37 ° C. for 2 hours.

  Thereafter, the medium is collected, and the enzyme activity of lactate dehydrogenase (LDH), which is an indicator of cell damage and cell death, is determined by Uniform LDH (manufactured by Roche) and a blood biochemical test automatic analyzer (trade names Cobasmira, Roche). The measurement was performed using An increase in the enzymatic activity of LDH means that cell damage and cell death have occurred.

  After removing the medium, the cells were fixed with 4% paraformaldehyde, anti-HSP72 antibody (Amersham) was added, and FITC-stained anti-mouse IgG (Jackson) was used for FITC staining. Cells having positive HSP72 concentration in the nucleus in 200 synovial cells were observed using a confocal laser microscope (model number TCS4D, manufactured by Leica), and the number of cells was measured. From these results, LDH enzyme activity, HSP72 staining concentration, and HSP72 nuclear positive cell appearance rate were determined, and Tukey statistical analysis was performed using the Yukms statistical library (manufactured by Yukkusu).

  The results are shown in Table 3.

  In this example, LDH activity was decreased in a concentration-dependent manner by the addition of hyaluronic acid oligosaccharide, and the staining of HSP72 and the appearance rate of cells positive for HSP72 in the cell nucleus were also increased by the addition of hyaluronic acid oligosaccharide. A concentration-dependent enhancement was observed significantly. Further, in this example, the system is different from the normal state in that heat stress is applied, and it is considered that oxygen radicals and hyaluronic acid degrading enzymes are hardly present. Therefore, HA84 is used instead of hyaluronic acid oligosaccharide. When the same test was performed, the expression of HSP72 was not enhanced. It was considered that the expression of HSP72 was not enhanced because the hyaluronic acid added to the system was hardly subjected to low molecular weight and did not become a low molecular weight hyaluronic acid such as an oligosaccharide.

  According to this example, it was shown that the damage of dog synovial cells due to heat shock was suppressed in a concentration-dependent manner by the addition of hyaluronic acid oligosaccharide. Moreover, HSP72 expression in cells and the appearance rate of HSP72 nuclear positive cells were significantly enhanced by the addition of hyaluronic acid oligosaccharide. It is known that HSP72, which is a stress protein, is expressed by stress and has a function of protecting cells from cell damage and cell death due to stress, in which case HSP72 is known to be localized in the nucleus (J Biol. Chem. 259 (1984) p4501-4513). From the above, it was suggested that the inhibition of cell damage and cell death by hyaluronic acid oligosaccharide was due to the hyaluronic acid oligosaccharide enhancing the expression of stress protein (HSP72 in this example).

Claims (9)

  A therapeutic agent for osteoarthritis or traumatic arthritis comprising 2 to 20 sugar hyaluronic acid oligosaccharides as an active ingredient.   A therapeutic agent for autoimmune diseases comprising 2 to 20 saccharides of hyaluronic acid oligosaccharide as an active ingredient.   A therapeutic agent for brain diseases or brain degenerative diseases, comprising 2 to 20 sugar hyaluronic acid oligosaccharides as an active ingredient.   A therapeutic agent for ischemic disease comprising 2 to 20 sugar hyaluronic acid oligosaccharide as an active ingredient.   A therapeutic agent for neurological diseases comprising 2 to 20 sugar hyaluronic acid oligosaccharide as an active ingredient.   A therapeutic agent for heart disease comprising 2 to 20 sugar hyaluronic acid oligosaccharides as an active ingredient.   A therapeutic agent for inflammation comprising 2 to 20 sugar hyaluronic acid oligosaccharides as an active ingredient.   A therapeutic agent for infectious diseases against bacterial or viral infection, comprising 2 to 20 saccharides of hyaluronic acid oligosaccharide as an active ingredient.   An antidiabetic agent comprising 2 to 20 sugar hyaluronic acid oligosaccharides as an active ingredient.