Compounds and their uses

Abstract

Provided is a compound having well-balanced LO· scavenging ability and LOO· scavenging ability.　A compound according to the present invention or a salt thereof is represented by formula (1). In formula (1), R1 and R2 may be the same or different and each independently represents a hydrogen atom or an alkyl group; R3 represents -OR4 or -NHR5; R4 represents a sec-butyl group, a tert-butyl group, or an iso-butyl group; and R5 represents a sec-butyl group, a tert-butyl group, or an iso-butyl group.

Description

[Technical field]

[0001] The present invention relates to a compound and its use. [Background technology]

[0002] Diseases in which lipid radicals in lipid peroxidation are involved cover a wide range of disease areas, including the cardiovascular system, central nervous system, respiratory system, and antibacterial drugs (Non-Patent Document 1). However, since many lipid peroxides and their metabolites are involved in each disease caused by lipid peroxidation, it is not easy to find a useful therapeutic drug for each disease. In addition, although many antioxidants are known, the only one approved as a drug is Edaravone (5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, trade name: Radicut, manufactured by Mitsubishi Tanabe Pharma Corporation). For this reason, there is a demand for providing a drug that exhibits an inhibitory effect on lipid peroxidation. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Jeroen Frijhoff et.al., “Clinical Relevance of Biomarkers of Oxidative Stress.”, Antioxidants & Redox Signaling, Vol. 23, No. 14, pages 1144-1170 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, as a result of intensive research, the present inventors have found that methyldopa (Aldomet (registered trademark)), an antihypertensive drug, functions as an antioxidant. However, the present inventors have found a problem in that, although methyldopa has a high peroxyl radical (LOO·) scavenging ability (LOO· scavenging ability), its alkoxyl radical (LO·) scavenging ability (LO· scavenging ability), which is considered to be more reactive than LOO·, is lower than its LOO· scavenging ability.

[0005] In addition, when the LO· and LOO· scavenging abilities of edaravone were examined, it was found that edaravone had similar scavenging abilities for LO· and LOO·. Therefore, when an antioxidant is used as a drug, it is considered desirable for the antioxidant to have a good balance between LO· and LOO· scavenging abilities.

[0006] Therefore, an object of the present invention is to provide a compound that has a better balance between LOO· and LO· scavenging ability than methyldopa. [Means for solving the problem]

[0007] In order to achieve the above object, the compound of the present invention or a salt thereof is represented by the following formula (1): [ka] In the formula (1), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 3 -OR 4 or -NHR 5 and R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group, R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

[0008] The pharmaceutical composition of the present invention comprises a compound of the present invention or a salt thereof and a pharma- ceutically acceptable carrier.

[0009] The antioxidant of the present invention includes a compound represented by the following formula (1A) or a salt thereof: [ka] In the formula (1A), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 3 -OR 4 or NHR 5 and R 4 is an alkyl group, R 5 is a hydrogen atom or an alkyl group.

[0010] The cell protective agent of the present invention includes the compound of the present invention or a salt thereof, or the antioxidant of the present invention.

[0011] The cell proliferation-promoting agent of the present invention comprises the compound of the present invention or a salt thereof, or the antioxidant of the present invention.

[0012] The antioxidant method of the present invention uses the antioxidant of the present invention.

[0013] The method for protecting cells of the present invention uses the cell protecting agent of the present invention.

[0014] The method for promoting cell proliferation of the present invention uses the cell proliferation promoter of the present invention. Effect of the Invention

[0015] The compound of the present invention or a salt thereof has a better balance between LOO· and LO· scavenging ability than methyldopa. [Brief description of the drawings]

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0017] <Compound or salt thereof> As described above, the compound of the present invention or a salt thereof is represented by the following formula (1): [ka] In the formula (1), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 3 -OR 4 or -NHR 5 and R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group, R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

[0018] The compound of the present invention or its salt is characterized by containing a compound represented by the formula (1) (hereinafter also referred to as the "compound of the present invention") or its salt, and other configurations and conditions are not particularly limited. The compound of the present invention or its salt has a better balance between LOO· scavenging ability and LO· scavenging ability than methyldopa. Therefore, it is presumed that the compound of the present invention or its salt functions as an excellent antioxidant in a living body. In the following description, unless otherwise specified, the description of the compound of the present invention can be used to describe the salt of the compound of the present invention or a solvate thereof.

[0019] The present inventors have conducted extensive research into compounds that have a better balance between LOO· and LO· scavenging abilities than methyldopa, and have found that compounds in which the carboxyl group of methyldopa has been esterified or in which the hydroxyl group of the carboxyl group has been amidated and an alkyl group has been introduced have the same or higher LO· scavenging ability than methyldopa, and have a better balance between LOO· and LO· scavenging abilities than methyldopa, thereby completing the present invention. The compounds of the present invention, for example, have LOO· and LO· scavenging abilities, and have a better balance between LOO· and LO· scavenging abilities than methyldopa. In addition to the LOO· and LO· scavenging abilities, the compounds of the present invention may have inhibitory activity against other lipid peroxidation reactions such as lipid radicals (L·). That is, the compounds of the present invention may have inhibitory activity against lipid peroxidation reactions caused by L· and the like, in addition to inhibitory activity against lipid radical reactions caused by LOO· and / or LO·.

[0020] As described above, the compound of the present invention has an alkoxyl radical scavenging ability. In the present invention, the "alkoxyl radical scavenging ability" means, for example, the ability to scavenge LO·. The LO· scavenging ability can be evaluated, for example, by an activity value. The activity value of the LO· scavenging ability can be evaluated, for example, by the activity value of the liposome-Fe in WO 2019 / 009355. 2+ More specifically, it can be measured according to the below-mentioned Example 1. As a specific example, the activity value of the LO· scavenging ability can be measured by the following steps (i) to (v). (i) preparing a buffer solution containing a compound represented by formula (A) and liposomes; (ii) adding a divalent iron ion source material; (iii) adding a test compound; (iv) measuring fluorescence; (v) From the results of the fluorescence measurement, the activity value of the test compound is calculated according to the following formula: LO scavenging activity value = 1-(AUC Sample / AUC Control ) AUC Sample :Fe 2+ Area under the curve calculated from the fluorescence intensity in the presence and absence of the test compound (n=1) AUC Control :Fe 2+ Area under the curve calculated from the fluorescence intensity with and without the test compound [ka]

[0021] In the above (i), the concentration of the compound represented by formula (A) is, for example, 1 to 20 μmol / l, typically 5 μmol / l. The liposome is, for example, prepared from egg yolk-derived phosphatidylcholine (Egg PC) and dihexadecyl hydrogen phosphate (DCP). The concentration of the egg yolk-derived phosphatidylcholine is, for example, 5 to 10 mg / ml, typically 2.5 mg / ml. The concentration of the dihexadecyl hydrogen phosphate is, for example, 0.01 to 1 mg / ml, typically 0.1 mg / ml.

[0022] In the above (ii), the concentration of the divalent iron ion source substance is, for example, 0.5 to 5 mmol / L, typically 1 mmol / L. The divalent iron ion source substance is, for example, iron (II) sulfate.

[0023] In the above (iii), the concentration of the test compound is 5 to 100 μmol / l, specifically, 10 μmol / l.

[0024] In the above (iv), the wavelength of the excitation light during the fluorescence measurement can be, for example, 470 nm, the fluorescence wavelength can be, for example, 530 nm, and the fluorescence intensity at 530 nm can be measured. The fluorescence measurement time is, for example, based on the above (iii), 0 to 240 minutes at 0.1 to 5 minute intervals, and typically 180 minutes at 3 minute intervals.

[0025] In the present invention, when the activity value of the LO· scavenging ability exceeds that of, for example, edaravone, the compound can be said to exhibit excellent LO· scavenging ability. The activity value of the LO· scavenging ability is, for example, 0.3 or more, preferably 0.4 or more.

[0026] As described above, the compound of the present invention has peroxyl radical scavenging ability. In the present invention, "peroxyl radical scavenging ability" means, for example, the ability to scavenge LOO·. The LOO· scavenging ability can be evaluated, for example, by an activity value. The activity value of the LOO· scavenging ability can be evaluated, for example, by the liposome-AAPH (2,2'-azobis(2-amidinopropane) dihydrochloride) system of International Publication No. 2019 / 009355, and more specifically, can be measured according to Example 1 described later. As a specific example, the activity value of the LOO· scavenging ability can be measured by the following steps (vi) to (x). (vi) preparing a buffer solution containing a compound represented by formula (A) and liposomes; (vii) adding 2,2'-azobis(2-amidinopropane) dihydrochloride; (viii) adding a test compound; (ix) measuring fluorescence; (x) From the results of the fluorescence measurement, the activity value of the test compound is calculated according to the following formula. LOO· scavenging activity value = 1-(Flu Sample -Flu Background ) / (Flu Control -Flu Background ) Flu Sample : Fluorescence intensity with AAPH and test compound (n=1) Flu Background : Fluorescence intensity without AAPH Flu Control : Fluorescence intensity with AAPH and without test compound

[0027] In the above (vi), the concentration of the compound represented by formula (A) is, for example, 1 to 20 μmol / l, typically 5 μmol / l. The liposome is, for example, prepared from egg yolk-derived phosphatidylcholine and dihexadecyl hydrogen phosphate. The concentration of the egg yolk-derived phosphatidylcholine is, for example, 5 to 10 mg / ml, typically 2.5 mg / ml. The concentration of the dihexadecyl hydrogen phosphate is, for example, 0.01 to 1 mg / ml, typically 0.1 mg / ml.

[0028] In the above (vii), the concentration of AAPH is, for example, 5 to 50 mmol / l, and typically 20 mmol / l.

[0029] In the above (viii), the concentration of the test compound is 5 to 100 μmol / l, specifically, 10 μmol / l.

[0030] In the above (ix), the wavelength of the excitation light during the fluorescence measurement can be, for example, 470 nm, the fluorescence wavelength can be, for example, 530 nm, and the fluorescence intensity at 530 nm can be measured. The fluorescence measurement time is, for example, 1 to 120 minutes, typically 30 to 40 minutes, based on the above (viii).

[0031] In the present invention, when the activity value of the LOO scavenging ability exceeds that of, for example, edaravone, the compound can be said to exhibit excellent LOO scavenging ability. The activity value of the LOO scavenging ability is, for example, 0.3 or more, preferably 0.4 or more.

[0032] In the present invention, the balance between the LO· scavenging ability and the LOO· scavenging ability can be expressed, for example, by the ratio (R / L) of the activity value (R) of the LO· scavenging ability and the activity value (L) of the LOO· scavenging ability. In the present invention, the excellent balance between the LO· scavenging ability and the LOO· scavenging ability means, for example, that the R / L of the test compound is within the range of 0.5 to 2, the range of 0.6 to 1.67, the range of 0.7 to 1.4, or the range of 0.8 to 1.25. By setting the R / L in such a range, the compound of the present invention can, for example, suitably capture both LO· and LOO·. The R / L of methyldopa is about 0.26.

[0033] Hereinafter, each substituent in the compound represented by formula (1) will be described with examples. In the description of each substituent, unless otherwise specified, the specific examples in the description of other substituents can be used. In addition, unless otherwise specified in the following description, the description of the compound represented by formula (1) can be used, for example, in the description of the salt of the compound represented by formula (1).

[0034] The compound of the present invention has an asymmetric carbon atom. Therefore, the compound of the present invention may exist, for example, as a racemate, its R and S enantiomers, or a mixture of R and S in any ratio. The compound of the present invention may have two or more asymmetric centers. In this case, the compound of the present invention may include diastereomers and mixtures thereof. When the compound of the present invention has a double bond in the molecule, the compound of the present invention may include, for example, geometric isomeric forms of cis and trans isomers. The compound of the present invention may exist, for example, as D-form and L-form, or a mixture thereof, and is preferably L-form. By making the compound of the present invention into an L-form, it is expected that the compound of the present invention will be efficiently taken up into cells, for example, by amino acid transporters.

[0035] R 1 and R 2are each a hydrogen atom, an alkyl group, or an acyl group. The alkyl group is, for example, a linear, branched, or cyclic saturated or unsaturated alkyl group having 1 to 6 carbon atoms. Specific examples of the alkyl group include, for example, a methyl group, an ethyl group, an n-propyl group, an iso(i)-propyl group, an n-butyl group, an i-butyl group, a tert(t)-butyl group, a sec(s)-butyl group, an n-pentyl group, an i-pentyl group, a t-pentyl group, an n-hexyl group, an i-hexyl group, a t-hexyl group, an n-heptyl group, an i-heptyl group, a t-heptyl group, an n-octyl group, an i-octyl group, a t-octyl group, an n-nonyl group, an i-nonyl group, a t- Examples of the alkyl group include a nonyl group, an n-decyl group, an i-decyl group, a t-decyl group, an n-undecyl group, an i-undecyl group, an n-dodecyl group, an i-dodecyl group, an n-tridecyl group, an i-tridecyl group, an n-tetradecyl group, an i-tetradecyl group, an n-pentadecyl group, an i-pentadecyl group, an n-hexadecyl group, an i-hexadecyl group, an n-heptadecyl group, an i-heptadecyl group, an n-octadecyl group, an i-octadecyl group, an n-nonadecyl group, and an i-nonadecyl group. The alkyl group is preferably, for example, a linear saturated alkyl group having 1 to 5 carbon atoms.

[0036] The acyl group (alkanoyl group) can be an acyl group having 1 to 6 carbon atoms. Examples of the acyl group include a formyl group, an acetyl group, a propynyl group, a butyryl group, an iso-butyryl group (an iso-valeryl group), a sec-butyryl group, a tert-butyryl group (a pivaloyl group), a valeryl group, and a hexanyl group (a caproyl group).

[0037] R 1 and R 2 may be, for example, a protecting group. Examples of the protecting group include a TBS (tert-butyldimethylsilyl group), an Fmoc group (fluorenylmethyloxycarbonyl chloride group), a Boc group (tert-butoxycarbonyl group), and a Cbz group (benzyloxycarbonyl group).

[0038] In the compound represented by the formula (1), the hydrogen of the amino group may be substituted with the protecting group.

[0039] In one embodiment, the compound represented by formula (1) is represented by the following formula (2), for example. [ka]

[0040] In the formula (2), R 1 and R 2 may be the same or different and are each independently a hydrogen atom or an alkyl group; R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

[0041] As a specific example, the compound represented by formula (1) is preferably a compound represented by formula (3) below. The compound represented by formula (3) below is, for example, more excellent in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (3) below can also be called, for example, s-butyl (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (3) below may form a hydrochloride salt. [ka]

[0042] As a specific example, the compound represented by formula (1) is preferably a compound represented by formula (4) below. The compound represented by formula (4) below is, for example, superior in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (4) below can also be called, for example, t-butyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (4) below may form a hydrochloride salt. [ka]

[0043] As a specific example, the compound represented by formula (1) is preferably a compound represented by formula (5) below. The compound represented by formula (5) below is, for example, superior in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (5) below can also be called, for example, isobutyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (5) below may form a hydrochloride salt. [ka]

[0044] In one embodiment, the compound represented by formula (1) is represented by the following formula (6), for example. [ka]

[0045] In the formula (6), R 1 and R 2 may be the same or different and are each independently a hydrogen atom or an alkyl group; R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

[0046] The compound represented by the formula (1) may be, for example, an isomer. The isomer may be, for example, a tautomer or a stereoisomer. The tautomer or stereoisomer may be, for example, all theoretically possible tautomers or stereoisomers. In the present invention, the configuration of each substituent is not particularly limited. The compound of the present invention may be, for example, a solvate such as a hydrate of the compound represented by the formula (1) or a salt thereof. Hereinafter, the description of the compound of the present invention can be used to describe the salt of the compound of the present invention or the solvate thereof.

[0047] In the present invention, the salt of the compound of the present invention is not particularly limited, and is, for example, a pharma- ceutically acceptable salt. The compound of the present invention forms, for example, an acid addition salt or a salt with a base, depending on the type of the substituent. The pharma-ceutically acceptable salt is not particularly limited, and for example, the pharma-ceutically acceptable salt is an alkali metal salt such as a sodium salt or a potassium salt; an alkaline earth metal salt such as a calcium salt or a magnesium salt; an ammonium salt; an aliphatic amine salt such as a trimethylamine salt, a triethylamine salt, a dicyclohexylamine salt, an ethanolamine salt, a diethanolamine salt, or a triethanolamine salt; an aralkylamine salt such as N,N-dibenzylethylenediamine; a heterocyclic aromatic amine salt such as a pyridine salt, a picoline salt, a quinoline salt, or an isoquinoline salt; a quaternary ammonium salt such as a tetramethylammonium salt, a tetraethylammonium salt, a benzyltrimethylammonium salt, a benzyltributylammonium salt, a methyltrioctylammonium salt, or a tetrabutylammonium salt; an arginine salt, a lysine salt, an aspartic acid salt, or a glutamic acid salt. salts of amino acids such as hydrochlorides, sulfates, nitrates, phosphates, carbonates, hydrogencarbonates, perchlorates, and other inorganic acid salts; salts of aliphatic organic acids or aromatic organic acids such as acetates, propionates, succinates, glycolates, lactates, maleates, fumarates, tartrates, malates, citrates, ascorbates, hydroxymaleates, pyruvates, phenylacetates, benzoates, 4-aminobenzoates, anthranilates, 4-hydroxybenzoates, salicylates, 4-aminosalicylates, pamoates, gluconates, and nicotinates; salts of sulfonates such as methanesulfonates, isethionates, ethanesulfonates, benzenesulfonates, halobenzenesulfonates, p-toluenesulfonates, toluenesulfonates, naphthalenesulfonates, sulfanilates, and cyclohexylsulfamates.

[0048] The compound of formula (1) and its salts can be produced by applying various known synthesis methods, utilizing the characteristics based on the basic structure or the type of substituent. In the production, for example, depending on the type of functional group, a protecting group may be introduced and reacted, and then the protecting group may be removed as necessary. The compound of formula (1) and its salts can be produced, for example, by esterifying the carboxyl group of methyldopa, or by amidating the hydroxyl group of the carboxyl group, and then introducing an alkyl group. The compound of formula (1) and its salts can be produced, for example, by acylating or etherifying the hydroxyl group of the catechol group as necessary.

[0049] <Pharmaceutical Composition> As described above, the pharmaceutical composition of the present invention comprises the compound of the present invention or a salt thereof and a pharma- ceutical acceptable carrier. The pharmaceutical composition of the present invention is characterized by comprising the compound of the present invention or a salt thereof, i.e., the compound represented by formula (1) or a salt thereof, and other configurations and conditions are not particularly limited. As described above, the compound of the present invention or a salt thereof has LO· scavenging ability and LOO· scavenging ability, and is superior in balance between LO· scavenging ability and LOO· scavenging ability compared to methyldopa. For this reason, the pharmaceutical composition of the present invention is expected to be applicable to the treatment of radical-induced diseases, such as those for which edaravone is used for treatment.

[0050] The pharmaceutical composition of the present invention can be, for example, in vivo You can also use in vitro may be used.

[0051] There are no particular limitations on the subjects to which the pharmaceutical composition of the present invention is administered. in vivo In the case of use in the above, the subject of administration can be, for example, a human or a non-human animal other than a human. Examples of the non-human animal include mammals such as mice, rats, rabbits, dogs, sheep, horses, cats, goats, monkeys, and guinea pigs, as well as birds and fish. invitro When used in the above, the subject to be administered can be, for example, a cell, tissue, organ, etc., the cell can be, for example, a cell collected from a living body, a cultured cell, etc., and the tissue or organ can be, for example, a tissue (living tissue) or an organ, etc. collected from a living body.

[0052] The conditions for using the compound of the present invention (administration conditions) are not particularly limited, and the administration form, administration time, administration amount, etc. can be appropriately set depending on, for example, the type of administration subject, etc.

[0053] The dosage of the compound of the present invention is not particularly limited. in vivo When used in the above, the dosage can be appropriately determined depending on, for example, the type, symptoms, age, administration method, etc. of the subject to be administered. As a specific example, when administered to humans, the total dosage of the compound per day is, for example, 0.01 to 50 mg / kg. The number of times of administration per day is, for example, 1 to 5 times.

[0054] The administration route of the pharmaceutical composition of the present invention is not particularly limited, and may be, for example, oral or parenteral.

[0055] The dosage form of the pharmaceutical composition of the present invention is not particularly limited and can be appropriately determined according to, for example, the administration form.The dosage form can be, for example, liquid or solid.When the administration form is oral administration, the dosage form can be, for example, tablets, pills, capsules, granules, powders, liquids, etc.

[0056] The pharmaceutical composition of the present invention may contain additives, for example, as necessary. When the pharmaceutical composition of the present invention is used as a medicine or pharmaceutical composition, the additives preferably contain pharma- ceutical acceptable additives or pharma-ceutical acceptable carriers. The additives are not particularly limited, and examples thereof include base materials, excipients, colorants, lubricants, binders, disintegrants, stabilizers, coating agents, preservatives, flavoring agents such as fragrances, etc. In the present invention, the amount of the additives is not particularly limited as long as they do not interfere with the function of the compound of the present invention.

[0057] Examples of the excipient include sugar derivatives such as lactose, lactose hydrate, sucrose, glucose, mannitol, and sorbitol; starch derivatives such as corn starch, potato starch, α-starch, and dextrin; cellulose derivatives such as crystalline cellulose; organic excipients such as gum arabic; dextran; and pullulan; silicate derivatives such as light anhydrous silicic acid, synthetic aluminum silicate, calcium silicate, and magnesium aluminometasilicate; phosphates such as calcium hydrogen phosphate; carbonates such as calcium carbonate; and sulfates such as calcium sulfate. Examples of the colorant include yellow ferric oxide. Examples of the lubricant include metal stearates such as stearic acid, calcium stearate, and magnesium stearate; talc; polyethylene glycol; silica; and hydrogenated vegetable oil. Examples of the flavoring agent include flavors such as cocoa powder, peppermint, aromatic powder, peppermint oil, borneol, and cinnamon powder, sweeteners, and acidulants. Examples of the binder include hydroxypropyl cellulose, hydroxypropyl methyl cellulose, polyvinylpyrrolidone, macrogol, etc. Examples of the disintegrant include cellulose derivatives such as carboxymethyl cellulose and carboxymethyl cellulose calcium; chemically modified starches and chemically modified celluloses such as carboxymethyl starch, carboxymethyl starch sodium, crosslinked polyvinylpyrrolidone, and sodium starch glycolate. Examples of the stabilizer include paraoxybenzoic acid esters such as methylparaben and propylparaben; alcohols such as chlorobutanol, benzyl alcohol, and phenylethyl alcohol; benzalkonium chloride; phenols such as phenol and cresol; thimerosal; dehydroacetic acid; sorbic acid, etc. Examples of the coating agent include macrogols such as hypromellose and macrogol 6000, talc, titanium oxide, etc.

[0058] <Antioxidants> In another aspect, the present invention provides an antioxidant having an excellent balance between LOO· scavenging ability and LO· scavenging ability. As described above, the antioxidant of the present invention comprises a compound represented by the following formula (1A) or a salt thereof: [ka] In the formula (1A), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 3 -OR 4 or -NHR 5 and R 4 is an alkyl group, R 5 is a hydrogen atom or an alkyl group.

[0059] The antioxidant of the present invention is characterized by containing a compound represented by formula (1A) or a salt thereof, and other configurations and conditions are not particularly limited. The antioxidant of the present invention can scavenge radicals because it contains a compound represented by formula (1A) or a salt thereof. In addition, the compound or a salt thereof in the antioxidant of the present invention has a better balance between LOO· scavengability and LO· scavengability compared to methyldopa. Therefore, it is presumed that the antioxidant of the present invention functions as an excellent antioxidant in a living body. In the following description, unless otherwise specified, the description of the compound in the antioxidant of the present invention can be used to describe the salt of the compound of the present invention or a solvate thereof. The description of the compound or salt and pharmaceutical composition of the present invention can be used to describe the antioxidant of the present invention.

[0060] In the present invention, the term "antioxidant" refers to, for example, an agent that captures radicals. Examples of the radicals include hydroxyl radical (·OH), alkoxy radical (alkoxyl radical, LO·), peroxy radical (peroxyl radical, LOO·), hydroperoxy radical (HOO·), nitric oxide (NO·), nitrogen dioxide (NO2·), superoxide anion (O2 - ), lipid radicals (L ), and other radical species; singlet oxygen ( 1Examples of the radicals include non-radical species such as ozone (O2), hydrogen peroxide (H2O2), etc. The antioxidant of the present invention may capture, for example, any one of the radicals, or may capture two or more of them. In the present invention, the "antioxidant" may capture one or more radicals. The capture of the radicals can also be referred to as, for example, scavenging of radicals. The capture of the radicals is carried out, for example, by the antioxidant of the present invention donating a hydrogen atom to the active oxygen species and converting the radical into another molecule (for example, water) that is more stable. The antioxidant of the present invention can also be referred to as, for example, a radical scavenger. In addition, the antioxidant of the present invention can prevent, inhibit, or suppress oxidation of other molecules coexisting with it by radicals. Therefore, the antioxidant of the present invention can also be referred to as, for example, an antioxidant, an oxidation inhibitor, or an oxidation suppressor. In addition, the antioxidant of the present invention has the ability to scavenge peroxyl radicals (LOO·) and alkoxyl radicals (LO·) involved in lipid peroxidation. For this reason, the antioxidant of the present invention can also be referred to as, for example, an agent for preventing, inhibiting and / or suppressing lipid peroxidation, an agent for preventing, inhibiting and / or suppressing the generation of lipid peroxides, etc. The antioxidant of the present invention may have inhibitory activity against other lipid peroxidation reactions such as lipid radicals (L·) in addition to the LOO· and LO· scavenging ability. That is, the antioxidant of the present invention may have inhibitory activity against lipid peroxidation reactions caused by L·, etc. in addition to the inhibitory activity against lipid radical reactions caused by LOO· and / or LO·.

[0061] The radical scavenging ability can be evaluated, for example, by the activity value of the LO· scavenging ability or the activity value of the LOO· scavenging ability described above. Specifically, when the activity value of the LO· scavenging ability of the test compound exceeds a predetermined value, or when the activity value of the LOO· scavenging ability of the test substance exceeds a predetermined value, the test compound can be said to have a radical scavenging ability. Specifically, when the activity value of the LO· scavenging ability of the test compound is, for example, 0.25 or more, the test compound can be said to have an LO· scavenging ability. Also, when the activity value of the LOO· scavenging ability of the test compound is, for example, 0.25 or more, the test compound can be said to have an LOO· scavenging ability.

[0062] As described above, the antioxidant of the present invention has an alkoxyl radical scavenging ability. In the present invention, the "alkoxyl radical scavenging ability" means, for example, the ability to scavenge LO·. The LO· scavenging ability can be evaluated, for example, by the activity value as described above.

[0063] In the antioxidant of the present invention, when the activity value of the LO· scavenging ability exceeds that of, for example, edaravone, the compound can be said to exhibit excellent LO· scavenging ability. The activity value of the LO· scavenging ability is, for example, 0.3 or more, preferably 0.4 or more.

[0064] In the antioxidant of the present invention, the compound represented by the formula (1A) has a peroxyl radical scavenging ability as described above. In the present invention, the "peroxyl radical scavenging ability" means, for example, the ability to scavenge LOO·. The LOO· scavenging ability can be evaluated, for example, by the activity value as described above.

[0065] In the compound represented by formula (1A) of the antioxidant of the present invention, when the activity value of the LOO scavenging ability exceeds that of, for example, edaravone, the compound can be said to exhibit excellent LOO scavenging ability. The activity value of the LOO scavenging ability is, for example, 0.3 or more, preferably 0.4 or more.

[0066] In the antioxidant of the present invention, the balance between the LO· scavenging ability and the LOO· scavenging ability can be expressed, for example, by the ratio (R / L) of the activity value (R) of the LO· scavenging ability to the activity value (L) of the LOO· scavenging ability. In the antioxidant of the present invention, the excellent balance between the LO· scavenging ability and the LOO· scavenging ability means, for example, that the R / L of the test compound is within the range of 0.5 to 2, the range of 0.6 to 1.67, the range of 0.7 to 1.4, or the range of 0.8 to 1.25. By setting the R / L in such a range, the antioxidant of the present invention can, for example, suitably capture both LO· and LOO·. The R / L of methyldopa is about 0.26.

[0067] Hereinafter, each of the substituents in the compound represented by formula (1A) will be described with examples. In the description of each substituent, unless otherwise specified, the specific examples in the description of other substituents can be used. In addition, unless otherwise specified in the following description, the description of the compound represented by formula (1A) can be used, for example, in the description of the salt of the compound represented by formula (1A).

[0068] The compound represented by formula (1A) has an asymmetric carbon atom. Therefore, the compound represented by formula (1A) may exist, for example, as a racemate, its R and S enantiomers, or a mixture of R and S in any ratio. The compound represented by formula (1A) may have two or more asymmetric centers. In this case, the compound represented by formula (1A) may include diastereomers and mixtures thereof. When the compound represented by formula (1A) has a double bond in the molecule, the compound represented by formula (1A) may include, for example, geometric isomers of cis and trans isomers. The compound represented by formula (1A) may exist, for example, as a D-form and an L-form, or a mixture thereof, and is preferably an L-form. By making the compound represented by formula (1A) into an L-form, for example, it is expected that the compound represented by formula (1A) will be efficiently taken up into cells by an amino acid transporter.

[0069] R 1 and R 2are each a hydrogen atom, an alkyl group, or an acyl group. The alkyl group is, for example, a linear, branched, or cyclic saturated or unsaturated alkyl group having 1 to 6 carbon atoms. Specific examples of the alkyl group include, for example, a methyl group, an ethyl group, an n-propyl group, an iso(i)-propyl group, an n-butyl group, an i-butyl group, a tert(t)-butyl group, a sec(s)-butyl group, an n-pentyl group, an i-pentyl group, a t-pentyl group, an n-hexyl group, an i-hexyl group, a t-hexyl group, an n-heptyl group, an i-heptyl group, a t-heptyl group, an n-octyl group, an i-octyl group, a t-octyl group, an n-nonyl group, an i-nonyl group, a t- Examples of the alkyl group include a nonyl group, an n-decyl group, an i-decyl group, a t-decyl group, an n-undecyl group, an i-undecyl group, an n-dodecyl group, an i-dodecyl group, an n-tridecyl group, an i-tridecyl group, an n-tetradecyl group, an i-tetradecyl group, an n-pentadecyl group, an i-pentadecyl group, an n-hexadecyl group, an i-hexadecyl group, an n-heptadecyl group, an i-heptadecyl group, an n-octadecyl group, an i-octadecyl group, an n-nonadecyl group, and an i-nonadecyl group. The alkyl group is preferably, for example, a linear saturated alkyl group having 1 to 5 carbon atoms.

[0070] The acyl group (alkanoyl group) can be an acyl group having 1 to 6 carbon atoms. Examples of the acyl group include a formyl group, an acetyl group, a propynyl group, a butyryl group, an iso-butyryl group (an iso-valeryl group), a sec-butyryl group, a tert-butyryl group (a pivaloyl group), a valeryl group, and a hexanyl group (a caproyl group).

[0071] R 1 and R 2 may be, for example, a protecting group. Examples of the protecting group include a TBS (tert-butyldimethylsilyl group), an Fmoc group (fluorenylmethyloxycarbonyl chloride group), a Boc group (tert-butoxycarbonyl group), and a Cbz group (benzyloxycarbonyl group).

[0072] R 4is an alkyl group. The alkyl group is preferably an ethyl group, a propyl group, a sec-butyl group, a tert-butyl group, or an iso-butyl group, and more preferably a sec-butyl group or a tert-butyl group.

[0073] R 5 is a hydrogen atom or an alkyl group. The alkyl group is preferably an ethyl group, a propyl group, a sec-butyl group, a tert-butyl group, or an iso-butyl group, and more preferably a sec-butyl group or a tert-butyl group.

[0074] In the compound represented by the formula (1A), the hydrogen of the amino group may be substituted with the protecting group.

[0075] In one embodiment, the compound represented by formula (1A) is represented, for example, by formula (2) below. [ka]

[0076] In the formula (2), R 1 and R 2 may be the same or different and are each independently a hydrogen atom or an alkyl group; R 4 is an alkyl group.

[0077] As a specific example, the compound represented by formula (1A) is preferably a compound represented by formula (3) below. The compound represented by formula (3) below is, for example, more excellent in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (3) below can also be called, for example, s-butyl (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (3) below may form a hydrochloride salt. [ka]

[0078] As a specific example, the compound represented by formula (1A) is preferably a compound represented by formula (4) below. The compound represented by formula (4) below is, for example, superior in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (4) below can also be called, for example, t-butyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (4) below may form a hydrochloride salt. [ka]

[0079] As a specific example, the compound represented by formula (1A) is preferably a compound represented by formula (5) below. The compound represented by formula (5) below is, for example, more excellent in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (5) below can also be called, for example, isobutyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (5) below may form a hydrochloride salt. [ka]

[0080] As a specific example, the compound represented by the formula (1A) is preferably a compound represented by the following formula (7). The compound represented by the following formula (7) is, for example, superior in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by the following formula (7) can also be called, for example, propyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by the following formula (7) may form a hydrochloride salt. [ka]

[0081] As a specific example, the compound represented by formula (1A) is preferably a compound represented by formula (8) below. The compound represented by formula (8) below is, for example, superior in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (8) below can also be called, for example, isopropyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (8) below may form a hydrochloride salt. [ka]

[0082] As a specific example, the compound represented by formula (1A) is preferably a compound represented by formula (9) below. The compound represented by formula (9) below is, for example, more excellent in the LO· scavenging ability and the LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (9) below can also be called, for example, butyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (9) below may form a hydrochloride salt. [ka]

[0083] As a specific example, the compound represented by formula (1A) is preferably a compound represented by formula (10) below. The compound represented by formula (10) below, for example, has superior LO· scavenging ability and LOO· scavenging ability, and has an excellent balance between the LO· scavenging ability and the LOO· scavenging ability. The compound represented by formula (10) below can also be called, for example, ethyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by formula (10) below may form a hydrochloride salt. [ka]

[0084] As a specific example, the compound represented by the formula (1A) is a compound represented by the following formula (11). The compound represented by the following formula (11) can also be called, for example, methyl (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoate. The compound represented by the following formula (11) may form a hydrochloride salt. [ka]

[0085] In one embodiment, the compound represented by formula (1A) is represented, for example, by formula (6) below. [ka]

[0086] In the formula (6), R 1 and R 2 may be the same or different and are each independently a hydrogen atom or an alkyl group; R 5 is a hydrogen atom or an alkyl group.

[0087] As a specific example, the compound represented by the formula (1A) is a compound represented by the following formula (12). The compound represented by the following formula (12) can also be called, for example, (S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanamide. The compound represented by the following formula (12) may form a hydrochloride salt. [ka]

[0088] The compound represented by formula (1A) may be, for example, an isomer. The isomer may be, for example, a tautomer or a stereoisomer. The tautomer or stereoisomer may be, for example, all theoretically possible tautomers or stereoisomers. In the present invention, the configuration of each substituent is not particularly limited. The antioxidant of the present invention may include, for example, a solvate such as a hydrate of the compound represented by formula (1A) or a salt thereof. Hereinafter, the description of the compound represented by formula (1A) may be used to describe the salt of the compound of the present invention or a solvate thereof.

[0089] In the antioxidant of the present invention, the salt of the compound represented by formula (1A) is not particularly limited, and is, for example, a pharma- ceutically acceptable salt. The compound represented by formula (1A) forms, for example, an acid addition salt or a salt with a base, depending on the type of the substituent. The pharma- ceutically acceptable salt is not particularly limited, and for example, the pharma- ceutically acceptable salt is an alkali metal salt such as a sodium salt or a potassium salt; an alkaline earth metal salt such as a calcium salt or a magnesium salt; an ammonium salt; an aliphatic amine salt such as a trimethylamine salt, a triethylamine salt, a dicyclohexylamine salt, an ethanolamine salt, a diethanolamine salt, or a triethanolamine salt; an aralkylamine salt such as N,N-dibenzylethylenediamine; a heterocyclic aromatic amine salt such as a pyridine salt, a picoline salt, a quinoline salt, or an isoquinoline salt; a quaternary ammonium salt such as a tetramethylammonium salt, a tetraethylammonium salt, a benzyltrimethylammonium salt, a benzyltributylammonium salt, a methyltrioctylammonium salt, or a tetrabutylammonium salt; an arginine salt, a lysine salt, an aspartate salt, or a glutamic acid salt. salts of amino acids such as hydrochlorides, sulfates, nitrates, phosphates, carbonates, hydrogencarbonates, perchlorates, and other inorganic acid salts; salts of aliphatic organic acids or aromatic organic acids such as acetates, propionates, succinates, glycolates, lactates, maleates, fumarates, tartrates, malates, citrates, ascorbates, hydroxymaleates, pyruvates, phenylacetates, benzoates, 4-aminobenzoates, anthranilates, 4-hydroxybenzoates, salicylates, 4-aminosalicylates, pamoates, gluconates, and nicotinates; salts of sulfonates such as methanesulfonates, isethionates, ethanesulfonates, benzenesulfonates, halobenzenesulfonates, p-toluenesulfonates, toluenesulfonates, naphthalenesulfonates, sulfanilates, and cyclohexylsulfamates.

[0090] The compound of formula (1A) and its salts can be produced by applying various known synthesis methods, utilizing the characteristics based on the basic structure or the type of substituent. In the production, for example, depending on the type of functional group, a protecting group may be introduced and reacted, and then the protecting group may be removed as necessary. The compound of formula (1A) or its salts can be produced, for example, by esterifying the carboxyl group of methyldopa, or by amidating the hydroxyl group of the carboxyl group, and then introducing an alkyl group. The compound of formula (1A) or its salts can be produced, for example, by acylating or etherifying the hydroxyl group of the catechol group as necessary.

[0091] The administration conditions of the antioxidant of the present invention are not particularly limited, and for example, the administration form, administration time, administration amount, etc. can be appropriately set depending on the type of administration subject, etc. For the administration subject and administration conditions of the antioxidant of the present invention, for example, the explanation of the administration subject and administration conditions of the compound of the present invention can be used.

[0092] <Cytoprotective agents> In another aspect, the present invention provides a compound that exhibits cytoprotective activity by being well balanced between LOO· scavenging ability and LO· scavenging ability. As described above, the cytoprotective agent of the present invention (hereinafter also referred to as "protective agent") contains the compound of the present invention or a salt thereof, or the antioxidant of the present invention. The protective agent of the present invention is characterized in that it contains the compound of the present invention or a salt thereof, or the antioxidant of the present invention, that is, it contains a compound represented by formula (1) or formula (1A) or a salt thereof, and other configurations and conditions are not particularly limited. Since the protective agent of the present invention contains a compound represented by formula (1) or formula (1A) or a salt thereof, it can scavenge radicals. Therefore, it is presumed that the cytoprotective agent of the present invention can suppress cell damage caused by the radicals. The protective agent of the present invention can be described by the compound or salt thereof, pharmaceutical composition, and antioxidant of the present invention.

[0093] In the present invention, "cell protection" refers to a state in which cell damage is (significantly) suppressed compared to the absence of the cell protective agent of the present invention (non-administration condition), and cell damage may progress compared to the start (start of administration). In this case, the "cell protection" can also be referred to as, for example, "suppression of cell damage". The cell damage refers to, for example, a decrease in cell function or dysfunction, and can be evaluated by cell metabolism, membrane permeability, etc.

[0094] The cells may be, for example, cells collected from a living body, cultured cells, or the like, or may be a cell sheet, cell mass (spheroid), tissue, or organ composed of cells.

[0095] The protective agent of the present invention can be suitably used, for example, to protect cells from cell death caused by radicals, particularly, to protect cells from cell death caused by ferroptosis. The term "ferroptosis" refers to cell death caused by oxidized lipids.

[0096] The administration conditions of the cell protective agent of the present invention are not particularly limited, and for example, the administration form, administration time, administration amount, etc. can be appropriately set depending on the type of administration subject, etc. For the administration subject and administration conditions of the cell protective agent of the present invention, for example, the explanation of the administration subject and administration conditions of the compound of the present invention can be used.

[0097] <Cell proliferation promoter> In another aspect, the present invention provides a compound capable of promoting cell proliferation. As described above, the cell proliferation promoter of the present invention (hereinafter also referred to as "promoters") contains the compound of the present invention or a salt thereof, or the antioxidant of the present invention. The promoter of the present invention is characterized by containing the compound of the present invention or a salt thereof, or the antioxidant of the present invention, that is, the compound represented by formula (1) or formula (1A) or a salt thereof, and other configurations and conditions are not particularly limited. The promoter of the present invention can promote cell proliferation by containing the compound represented by formula (1) or formula (1A) or a salt thereof. The protective agent of the present invention can be described in the same manner as the compound or salt, pharmaceutical composition, and antioxidant of the present invention.

[0098] In the present invention, "promotion of cell proliferation" may mean that cell proliferation is (significantly) improved as compared to the absence of the promoter of the present invention (non-administration condition), and may mean that cell proliferation is decreased as compared to the start (start of administration). In this case, the "promotion of cell proliferation" can also be referred to as, for example, "suppression of the decrease in cell proliferation".

[0099] The cells may be, for example, cells collected from a living body, cultured cells, or the like, or may be a cell sheet, a cell mass (spheroid), a tissue, or an organ composed of cells. Examples of the cells include nerve cells.

[0100] The administration conditions of the enhancer of the present invention are not particularly limited, and for example, the administration form, administration time, administration amount, etc. can be appropriately set depending on the type of the administration subject, etc. For the administration subject and administration conditions of the enhancer of the present invention, for example, the explanation of the administration subject and administration conditions of the compound of the present invention can be used.

[0101] <How to prevent oxidation> In another aspect, the present invention provides an antioxidant method having a good balance between LOO· scavenging ability and LO· scavenging ability. As described above, the antioxidant method of the present invention uses the antioxidant of the present invention. The antioxidant method of the present invention is characterized by using the antioxidant of the present invention, that is, using the compound represented by the formula (1A) or a salt thereof, and other steps and conditions are not particularly limited. The antioxidant method of the present invention uses the antioxidant of the present invention, and therefore can capture radicals. Therefore, according to the antioxidant method of the present invention, for example, oxidation of other molecules that coexist can be prevented. The antioxidant method of the present invention can be applied to the explanation of the compound or salt, pharmaceutical composition, and antioxidant of the present invention.

[0102] The antioxidant method of the present invention can, for example, suppress or inhibit oxidation caused by radicals of other molecules present in the presence of the antioxidant. Therefore, the antioxidant method of the present invention can also be referred to as, for example, an oxidation suppression method or an oxidation inhibition method. The antioxidant of the present invention has the ability to eliminate peroxyl radicals (LOO·) and alkoxyl radicals (LO·) involved in lipid peroxidation. Therefore, the antioxidant method of the present invention can also be referred to as, for example, a method for preventing, inhibiting and / or suppressing lipid peroxidation, a method for preventing, inhibiting and / or suppressing the generation of lipid peroxidation, etc.

[0103] The antioxidant method of the present invention includes, for example, a contacting step of contacting with the antioxidant. More specifically, the antioxidant method of the present invention includes, for example, a contacting step of contacting the antioxidant with a target to be antioxidant. The antioxidant method of the present invention may include, for example, a coexistence step of coexisting with the antioxidant instead of or in addition to the contacting step. More specifically, the coexistence step includes, for example, coexistence of the target to be antioxidant with the antioxidant. The coexistence means, for example, that the antioxidant is simultaneously present in the same agent, composition, or space separated from the target to be antioxidant.

[0104] The target of oxidation prevention is not particularly limited and can be any target.

[0105] In the antioxidation method of the present invention, the compound of the present invention or a salt thereof may be used in place of or in addition to the antioxidant of the present invention.

[0106] In the antioxidant method of the present invention, the contact step and the coexistence step can be carried out, for example, as follows: in vitro or in vivo For the subjects and conditions for administration of the antioxidant of the present invention, the explanation of the subjects and conditions for administration of the compound of the present invention can be cited, for example.

[0107] <How to protect cells> In another aspect, the present invention provides a method capable of protecting cells by having an excellent balance between LOO· scavenging ability and LO· scavenging ability. As described above, the cell protection method of the present invention (hereinafter also referred to as "protection method") uses the cell protective agent of the present invention. The protection method of the present invention is characterized by using the cell protective agent of the present invention, that is, using the compound represented by formula (1) or formula (1A) or a salt thereof, and other steps and conditions are not particularly limited. The protection method of the present invention can capture radicals because it uses the protective agent of the present invention. Therefore, it is expected that the protection method of the present invention can suppress cell damage caused by the radicals. The protection method of the present invention can be described by using the explanations of the compound or salt, antioxidant, pharmaceutical composition, and cell protective agent of the present invention.

[0108] The protection method of the present invention includes, for example, a coculture step of coculture of cells with the cell protective agent. In the coculture step, the cells may be contacted with the cell protective agent. In this case, the coculture step can also be referred to as, for example, a contact step.

[0109] In the protection method of the present invention, the coexistence step may, for example, in vitro or in vivo For the subjects and conditions for administration of the protective agent of the present invention, the explanation for the subjects and conditions for administration of the antioxidant of the present invention can be cited, for example.

[0110] <Method of promoting cell proliferation> In another aspect, the present invention provides a method capable of promoting cell proliferation. As described above, the cell proliferation promoting method of the present invention (hereinafter also referred to as the "promotion method") uses the cell proliferation promoting agent of the present invention. The promotion method of the present invention is characterized by using the promoter of the present invention, i.e., using the compound represented by formula (1) or formula (1A) or a salt thereof, and other steps and conditions are not particularly limited. The promotion method of the present invention can promote cell proliferation since it uses the promoter of the present invention. The promotion method of the present invention can refer to the explanations of the compound or salt, antioxidant, pharmaceutical composition, cell protective agent, and cell proliferation promoting agent of the present invention.

[0111] The promotion method of the present invention includes, for example, a coculture step of coculture of cells with the promoter. In the coculture step, the cells may be contacted with the promoter. In this case, the coculture step can also be referred to as, for example, a contact step.

[0112] In the promotion method of the present invention, the coexistence step may, for example, in vitro or in vivo For the subjects and conditions for administration of the promoter of the present invention, the explanation of the subjects and conditions for administration of the antioxidant of the present invention can be cited, for example.

[0113] <Use of the compound or its salt> The present invention relates to the use of the compound represented by the formula (1) or formula (1A) or a salt thereof for use in antioxidants, the use of the compound represented by the formula (1) or formula (1A) or a salt thereof for use in cell protection, and the use of the compound represented by the formula (1) or formula (1A) or a salt thereof for use in promoting cell proliferation. The present invention also relates to the use of the compound represented by the formula (1) or formula (1A) or a salt thereof for producing an antioxidant, the use of the compound represented by the formula (1) or formula (1A) or a salt thereof for producing a cell protective agent, and the use of the compound represented by the formula (1) or formula (1A) or a salt thereof for producing a cell proliferation promoter. The compound represented by the formula (1) or formula (1A) may be the compound represented by formula (1) in the compound of the present invention, or may be the compound represented by formula (1) or formula (1A) in the antioxidant of the present invention. The present invention can be applied to, for example, the above-described descriptions of the compound or a salt thereof, pharmaceutical composition, antioxidant, protective agent, promoter, method for preventing oxidation, method for protecting, and method for promoting. EXAMPLES

[0114] Next, examples of the present invention will be described. However, the present invention is not limited to the following examples. Commercially available reagents were used according to their protocols unless otherwise specified.

[0115] [Example 1] Compounds represented by formulae (3) to (5) and (7) to (9) were obtained according to the synthesis examples shown below.

[0116] Electrospray ionization mass spectrometry (ESI-MS) was carried out in positive ion mode using a mass spectrometer (LCMS-2020, manufactured by Shimadzu Corporation). The analysis conditions were as follows. Interface: Interface: ESI DL Temperature: 250℃ Nebulizing Gas Flow:1.5 l / min Heat Block: 250℃ Drying Gas: On (15.00 l / min) column: Column Name: Ascentis Express C18 (SIGMA) Length: 50mm Internal Diameter: 3.0 mm Description: 2.7μm pump: Mode: Binary gradient Pump A: LC-30AD Pump B: LC-30AD Total Flow: 1.5ml / min B Conc.: 5.0% oven: Oven Temperature: 40℃ PDA: PDA Model: SPD-M20A Lamp: D2 Start Wavelength: 190 nm End Wavelength: 400 nm solvent: Mobile phase A: Water / 0.05% trifluoroacetic acid (TFA) Mobile phase B: Acetonitrile / 0.05% TFA Time Program (Gradient): Time (min) 0 2 2.7 Mobile phase A 95 0 0 Mobile phase B 5 100 100

[0117] (Synthesis of compound (1b)) Compound (1b) was synthesized from methyldopa (compound (1a)) according to the following scheme 1. [ka]

[0118] (Synthesis of compound (1c)) Compound (1c) was synthesized from compound (1b) according to the following scheme 2. [ka]

[0119] (Synthesis of compound (3a)) Compound (3a) was synthesized from compound (1c) according to the following scheme 3. [ka]

[0120] (Synthesis of compound (3)) Compound (3) was synthesized from compound (3a) according to the following scheme 4. The physical properties are shown below. The NMR measurement results are shown in FIG. 1. ESI-MS (positive ion mode) m / z, found = 268.15, calculated for [(M+H)+] = 268.15 [ka]

[0121] (Synthesis of compound (1d)) Compound (1d) was synthesized from compound (1c) according to the following scheme 5. [ka]

[0122] (Synthesis of compound (4a)) Compound (4a) was synthesized from compound (1d) according to the following scheme 6. [ka]

[0123] (Synthesis of compound (4)) Compound (4) was synthesized from compound (4a) according to the following scheme 7. The physical properties are shown below. The NMR measurement results are shown in FIG. 2. ESI-MS (positive ion mode) m / z, found = 268.05, calculated for [(M+H)+] = 268.15 [ka]

[0124] (Synthesis of compound (5)) Compound (5) was synthesized from compound (1a) according to the following scheme 8. The physical properties are shown below. The NMR measurement results are shown in FIG. 3. ESI-MS (positive ion mode) m / z, found = 268.10, calculated for [(M+H)+] = 268.15 [ka]

[0125] (Synthesis of compound (7)) Compound (7) was synthesized from compound (1c) according to the following scheme 9. [ka]

[0126] (Synthesis of compound (8a)) Compound (8a) was synthesized from compound (1c) according to the following scheme 10. [ka]

[0127] (Synthesis of compound (8)) Compound (8) was synthesized from compound (8a) according to the following scheme 11. [ka]

[0128] (Synthesis of compound (9a)) Compound (9a) was synthesized from compound (1c) according to the following scheme 12. [ka]

[0129] (Synthesis of compound (9)) Compound (9) was synthesized from compound (9a) according to the following scheme 13. [ka]

[0130] [Example 2] It was confirmed that the compound of the present invention or the antioxidant of the present invention has the LO· scavenging ability and the LOO· scavenging ability, and is superior in balance between the LO· scavenging ability and the LOO· scavenging ability as compared with methyldopa.

[0131] (1) Measurement of LO scavenging activity Solution A was prepared containing 20 μmol / l of liposomes (10 mg / ml Egg PC, 0.4 mg / ml DCP) and NBD-TEEPO compound (compound represented by formula (A)) in phosphate buffer (10 mmol / l, pH 7.4, 2.0% acetonitrile), and solution B was prepared containing 4.0 mmol / l of FeSO4 in distilled water. 10 μl of solutions A and B were each dispensed and mixed using a Multidrop Combi (Thermo Fisher Scientific). The final concentrations were liposomes (2.5 mg / ml Egg PC, 0.1 mg / ml DCP), NBD-TEEPO compound 5.0 μmol / l, test compound 10 μmol / l, and FeSO4 1.0 mmol / l in phosphate buffer (10 mmol / l, pH 7.4, 0.5% acetonitrile, 1% dimethyl sulfoxide (DMSO)). The test compounds used were the compounds represented by the formulas (3) to (5) and (7) to (10) as examples, the compound represented by the formula (1a) (methyldopa) as a comparative example, and edaravone and SCREEN-WELL (registered trademark) FDA approved drug library (manufactured by Enzo Life Sciences) as reference examples, and were dissolved in DMSO before use.

[0132] Then, while incubating at 37℃, the fluorescence intensity was measured over time at 3-minute intervals up to 180 minutes, starting from the time of mixing. The fluorescence intensity was measured under conditions of an excitation wavelength of 470 nm and a fluorescence wavelength of 530 nm. A curve was then created from the obtained fluorescence intensity, and the activity value of the LO scavenging ability was calculated based on this using the above-mentioned formula.

[0133] (2) Measurement of LOO scavenging activity Solution A was prepared containing liposomes (10 mg / ml Egg PC, 0.4 mg / ml DCP) and NBD-TEEPO compound (20 μmol / l) in phosphate buffer (10 mmol / l, pH 7.4, 2.0% acetonitrile), and solution B was prepared containing AAPH 80 mmol / l in phosphate buffer (10 mmol / l, pH 7.4). 10 μl of each of solutions A and B was dispensed and mixed using a Multidrop Combi. The final concentrations were liposomes (2.5 mg / ml Egg PC, 0.1 mg / ml DCP), NBD-TEEPO compound 5.0 μmol / l, each test compound 10 μmol / l, and AAPH 20 mmol / l in phosphate buffer (10 mmol / l, pH 7.4, 0.5% acetonitrile, 1% DMSO).

[0134] The mixture was incubated at 37°C and the fluorescence intensity was measured 40 minutes later, with the intensity measured at the time of mixing as the base line. The fluorescence intensity was measured under conditions of an excitation wavelength of 470 nm and a fluorescence wavelength of 530 nm. Based on the obtained fluorescence intensity, the activity value of the LOO scavenging ability was calculated using the above formula.

[0135] (3) Results These results are shown in FIG. 4 and Table 1 below. FIG. 4 is a graph showing LO· scavenging ability and LOO· scavenging ability. In FIG. 4, the horizontal axis shows LOO· scavenging ability (AAPH stimulation), and the vertical axis shows LO· scavenging ability (Fe stimulation). As shown in FIG. 4 and Table 1 below, all of the compounds of the examples showed superior LO· scavenging ability and LOO· scavenging ability compared to edaravone. In addition, the R / L of methyldopa was 0.26, whereas the R / L of the compounds of the formulas (3) to (5) and (7) to (10) was 1.04, 1.07, 1.19, 0.88, 0.95, 1.04, and 0.78, respectively, showing an excellent balance between LO· scavenging ability and LOO· scavenging ability. In addition, the compounds of the formulas (3) to (5) showed superior LO· scavenging ability compared to methyldopa.

[0136] [Table 1]

[0137] From the above, it was found that the compound of the present invention and the antioxidant of the present invention have LO· and LOO· scavenging ability, and have a better balance of LO· and LOO· scavenging ability than methyldopa. In addition, it is known that compounds having LO· and LOO· scavenging ability can protect cells from radicals. Therefore, the compound of the present invention is expected to be extremely excellent not only as an antioxidant but also as a cell protection agent.

[0138] [Example 3] It was confirmed that the compounds of the present invention can effectively suppress ferroptosis and have the ability to promote cell proliferation.

[0139] Mouse hippocampal neuron cells (HT-22, Merck) were cultured at 5.0 × 10 3 The neurons were seeded at 100 μl / well and cultured for 24 hours. The neurons were used after 4 passages after purchase. The culture medium used was DMEM (High Glucose, Nacalai Tesque) containing 10% fetal bovine serum (Nacalai Tesque) and 1× penicillin / streptomycin (Nacalai Tesque). The culture conditions were 37°C, 5% CO2, and humid environment.

[0140] After the culture, a sample solution containing the compound represented by formulas (3) to (5) or methyldopa and a ferroptosis inducer (elastin (Cayman Chemical Company), RSL-3 (Sigma-Aldrich)) was added at 100 μl / well. The compound represented by formulas (3) to (5) or methyldopa was added so that the final concentration in each well was a predetermined concentration (0 (control), 1, 3, or 10 μmol / l). The ferroptosis inducer was added so that the final concentration in each well was a predetermined concentration (elastin: 0.2 μmol / l, RSL-3: 0.05 μmol / l). After the addition, MTT reagent (Nacalai Tesque) was added at 15 μl / well, and cultured for 2 hours under the culture conditions.

[0141] Next, the medium was aspirated from each well, DMSO was added at 100 μl / well, and the absorbance at 570 nm and 650 nm was measured for each well using an EnSpire plate reader (PerkinElmer). The absorbance of the formazan dye (570 nm) and the background absorbance (650 nm) were used as the index value of the cell viability of each well. In addition, the index value of the control group was determined in the same manner, except that the compounds represented by the formulas (3) to (5) or methyldopa and the ferroptosis inducer were not added. The index value of the control was set as 100% viability, and the relative value of the cell viability of each drug treatment group was calculated. These results are shown in FIG. 5.

[0142] FIG. 5 is a graph showing the cell viability. In FIG. 5, the horizontal axis indicates the type of sample or the concentration of the compound represented by the formulas (3) to (5) or methyldopa, and the vertical axis indicates the cell viability. In each graph, each bar indicates the results of the control (ctrl), the compound represented by the formulas (3) to (5) or methyldopa at a concentration of 0 (-), 1, 3, or 10 μmol / l, from the left. As shown in FIG. 5, the compound represented by the formulas (3) to (5) suppressed ferroptosis in a concentration-dependent manner. In addition, the compound represented by the formulas (3) to (5) had a significantly higher degree of suppression of ferroptosis than methyldopa. As described above, the compound represented by the formulas (3) to (5) has a better balance of LO· scavenging ability and LOO· scavenging ability than methyldopa. For this reason, it was presumed that the compound represented by the formulas (3) to (5) exerts a cytoprotective function by effectively scavenging these radicals that cause ferroptosis.

[0143] 5, in the group containing the compounds represented by the formulas (3) to (5) at a concentration of 10 μmol / l, the cell survival rate was improved compared to the control. That is, the cell proliferation was improved. Therefore, it was found that the compound of the present invention has the ability to promote cell proliferation.

[0144] From the above, it was found that the compound of the present invention can effectively suppress ferroptosis and has the ability to promote cell proliferation.

[0145] [Example 4] It was confirmed that the compound of the present invention has the ability to promote cell proliferation.

[0146] In the same manner as in Example 3, the mouse hippocampal neuron cells were seeded in a 96-well flat-bottom plate and cultured for 24 or 48 hours. Before the culture, a sample solution containing the compounds represented by formulas (3) to (5) was added at 100 μl / well. The compounds represented by formulas (3) to (5) were added so that the final concentration in each well became a predetermined concentration (0 (control), 3, or 10 μmol / l). After the culture, MTT reagent (manufactured by Nacalai Tesque) was added at 15 μl / well, and the cells were cultured under the culture conditions for 2 hours.

[0147] After the culture, the index value was determined for each well in the same manner as in Example 3. The index value for the control was set as 100% survival rate, and the relative cell survival rate for each drug treatment group was calculated. These results are shown in Figure 6.

[0148] FIG. 6 is a graph showing the cell viability. In FIG. 6, the horizontal axis shows the type of sample or the concentration of the compound represented by the formulas (3) to (5), and the vertical axis shows the cell viability. In FIG. 6, (A) shows the result after 24 hours of culture, and (B) shows the result after 48 hours. As shown in FIG. 6, the compounds represented by the formulas (3) to (5) all improved the cell viability compared to the control. That is, cell proliferation was improved. Therefore, it was confirmed that the compound of the present invention has the ability to promote cell proliferation. In addition, the compound of the present invention functions as an antioxidant as described above. Therefore, it was presumed that the compound of the present invention promotes cell proliferation by its antioxidant function in cells.

[0149] Although the present invention has been described above with reference to the embodiments and examples, the present invention is not limited to the above-mentioned embodiments and examples. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0150] This application claims priority based on Japanese Patent Application No. 2020-023164 and Japanese Patent Application No. 2020-023221, filed on February 14, 2020, the disclosures of which are incorporated herein in their entirety.

[0151] <Additional Notes> Some or all of the above-described embodiments and examples may be described as follows, but are not limited to the following: (Appendix 1) A compound represented by the following formula (1) or a salt thereof: [ka] In the formula (1), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 3 -OR 4 or -NHR 5 and R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group, R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group. (Appendix 2) A compound according to appended claim 1, represented by the following formula (2) or a salt thereof: [ka] In the formula (2), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group. (Appendix 3) A compound according to appendix 1 or 2, which is represented by the following formula (3) or a salt thereof: [ka] (Appendix 4) A compound according to appendix 1 or 2, represented by the following formula (4), or a salt thereof: [ka] (Appendix 5) A compound according to appendix 1 or 2, represented by the following formula (5), or a salt thereof: [ka] (Appendix 6) The compound according to appended claim 1, represented by the following formula (6) or a salt thereof: [ka] In the formula (6), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group. (Appendix 7) A pharmaceutical composition comprising a compound according to any one of claims 1 to 6 or a salt thereof and a pharma- ceutically acceptable carrier. (Appendix 8) An antioxidant comprising a compound represented by the following formula (1A) or a salt thereof: [ka] In the formula (1A), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 3 -OR 4 or NHR 5 and R 4 is an alkyl group, R 5 is a hydrogen atom or an alkyl group. (Appendix 9) The antioxidant according to appendix 8, represented by the following formula (2): [ka] In the formula (2), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 4 is an alkyl group. (Appendix 10) 10. An antioxidant according to claim 8 or 9, represented by the following formula (3): [ka] (Appendix 11) 10. An antioxidant according to claim 8 or 9, represented by the following formula (4): [ka] (Appendix 12) 10. An antioxidant according to claim 8 or 9, represented by the following formula (5): [ka] (Appendix 13) 10. An antioxidant according to claim 8 or 9, represented by the following formula (7): [ka] (Appendix 14) 10. An antioxidant according to claim 8 or 9, represented by the following formula (8): [ka] (Appendix 15) An antioxidant according to claim 8 or 9, represented by the following formula (9): [ka] (Appendix 16) 10. An antioxidant according to claim 8 or 9, represented by the following formula (10): [ka] (Appendix 17) The antioxidant according to appendix 8, represented by the following formula (6): [ka] In the formula (6), R 1 and R 2 may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R 5 is a hydrogen atom or an alkyl group. (Appendix 18) A cytoprotective agent comprising a compound or a salt thereof according to any one of Appendices 1 to 6, or an antioxidant according to any one of Appendices 8 to 17. (Appendix 19) A cell proliferation promoter comprising a compound or a salt thereof according to any one of Appendices 1 to 6, or an antioxidant according to any one of Appendices 8 to 17. (Appendix 20) A method for preventing oxidation, comprising using an antioxidant according to any one of claims 8 to 17. (Appendix 21) 21. The method for preventing oxidation according to claim 20, comprising a contacting step of contacting with the antioxidant. (Appendix 22) A method for protecting cells, comprising using the cell protective agent described in appendix 18. (Appendix 23) 23. A method for protecting cells according to claim 22, comprising coexisting cells with the cell protective agent. (Appendix 24) A method for promoting cell proliferation, comprising using the cell proliferation promoter described in appendix 19. (Appendix 25) 25. The method for promoting cell proliferation according to claim 24, wherein the cells are allowed to coexist with the cell proliferation promoter. (Appendix 26) Use of a compound represented by formula (1) or formula (1A) or a salt thereof for use in antioxidant purposes. (Appendix 27) Use of a compound represented by formula (1) or formula (1A) or a salt thereof for cell protection. (Appendix 28) Use of a compound represented by formula (1) or formula (1A) or a salt thereof for promoting cell proliferation. [Industrial Applicability]

[0152] As described above, the compound of the present invention or its salt has a better balance between LO· scavenging ability and LOO· scavenging ability than methyldopa. Therefore, the compound of the present invention is expected to be applicable to the treatment of diseases caused by radicals, such as those for which edaravone is used for treatment. Therefore, the present invention is extremely useful in the fields of medicine, etc.

Claims

1. A compound represented by the following formula (3) or (5) or a salt thereof: 【Chemistry 3】 【Chemistry 5】

2. A pharmaceutical composition comprising a compound represented by the following formula (1) or a salt thereof and a pharma- ceutically acceptable carrier: In the formula (1), R 1 and R 2 may be the same or different and each independently represents a hydrogen atom, an alkyl group, or an acyl group; R 3 is —OR 4 or —NHR 5 ; R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group; R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

3. An antioxidant comprising a compound represented by the following formula (1A) or a salt thereof: 【Chemistry 1A】 In the formula (1A), R １ and R ２ may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R ３ is -OR ４ or N.H.R. ５ and R ４ is an alkyl group, R ５ is a hydrogen atom or an alkyl group.

4. The antioxidant according to claim 3, represented by the following formula (2): 【Chemistry 2】 In the formula (2), R １ and R ２ may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R ４ is an alkyl group.

5. The antioxidant according to claim 3 or 4, which is represented by the following formula (3): 【Chemistry 3】

6. The antioxidant according to claim 3 or 4, which is represented by the following formula (4): 【Chemistry 4】

7. The antioxidant according to claim 3 or 4, which is represented by the following formula (5): 【Chemistry 5】

8. The antioxidant according to claim 3 or 4, which is represented by the following formula (7): 【Chemistry 7】

9. The antioxidant according to claim 3 or 4, which is represented by the following formula (8): 【Chemistry 8】

10. The antioxidant according to claim 3 or 4, which is represented by the following formula (9): 【Chemistry 9】

11. The antioxidant according to claim 3 or 4, which is represented by the following formula (10): 【Chemistry 10】

12. The antioxidant according to claim 3, represented by the following formula (6): 【Chemistry 6】 In the formula (6), R １ and R ２ may be the same or different and are each independently a hydrogen atom, an alkyl group, or an acyl group; R ５ is a hydrogen atom or an alkyl group.

13. A cell protective agent comprising a compound represented by the following formula (1) or a salt thereof, or an antioxidant described in any one of claims 3 to 12. 【Chemistry 1】 In the formula (1), R 1 and R 2 may be the same or different and each independently represents a hydrogen atom, an alkyl group, or an acyl group; R 3 is —OR 4 or —NHR 5 ; R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group; R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

14. A cell proliferation promoter comprising a compound represented by the following formula (1) or a salt thereof, or an antioxidant described in any one of claims 3 to 12. 【Chemistry 1】 In the formula (1), R 1 and R 2 may be the same or different and each independently represents a hydrogen atom, an alkyl group, or an acyl group; R 3 is —OR 4 or —NHR 5 ; R 4 is a sec-butyl group, a tert-butyl group, or an iso-butyl group; R 5 is a sec-butyl group, a tert-butyl group, or an iso-butyl group.

15. 13. A method for preventing oxidation, comprising using an antioxidant according to any one of claims 3 to 12 in vitro or in vivo (except in humans).

16. The method for preventing oxidation according to claim 15, further comprising a contacting step of contacting with an antioxidant.

17. A method for protecting cells, comprising using the cell protective agent according to claim 13 in vitro or in vivo (except in humans).

18. The method for protecting cells according to claim 17 , wherein the cells are coexistent with the cell protective agent.

19. A method for promoting cell proliferation, comprising using the cell proliferation promoter according to claim 14 in vitro or in vivo (except in humans).

20. The method for promoting cell proliferation according to claim 19 , wherein the cells are allowed to coexist with the cell proliferation promoter.

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