Lithocholic acid derivatives with vitamin D activity

Abstract

To provide new lithocholic acid derivatives with sufficient vitamin D3 activity.SOLUTION: The invention provides a compound represented by the general formula (I) in the figure, a salt thereof, or a prodrug thereof. (In the formula, R1 and R2 each independently denote a hydrogen atom or an optionally substituted C1-8 alkyl group; X denotes -O- or -NR4-; R3 and R4 each independently denote a hydrogen atom or an optionally substituted C1-8 alkyl group.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to lithocholic acid derivatives having vitamin D activity. The present invention further relates to medicines, vitamin D receptor activators, and agents for preventing and / or treating vitamin D receptor-related diseases, each containing the lithocholic acid derivative. [Background technology]

[0002] Vitamin D binds to the vitamin D receptor (VDR) via its metabolically activated form, 1α,25-dihydroxyvitamin D3, and regulates the expression of specific genes. This gene regulation contributes to important physiological functions, including maintaining blood calcium levels, bone formation, immune function, and cell differentiation and proliferation. Numerous VDR ligands have been developed for the development of therapeutic drugs for osteoporosis, psoriasis, and cancer, some of which are in clinical use as pharmaceuticals. Most existing VDR ligands share a secosteroid backbone, similar to natural 1α,25-dihydroxyvitamin D3. While the secosteroid backbone is useful for developing highly active derivatives, its chemical stability and complex synthesis generally limit the potential for diverse pharmaceutical applications of vitamin D. Therefore, the development of VDR ligands with non-secosteroid backbones is highly desirable, but few such non-secosteroid VDR ligands have been reported.

[0003] Lithocholic acid has been found to be an endogenous ligand for VDR, but its affinity for VDR is very weak, and its physiological significance is unknown. Patent Document 1 describes that lithocholic acid derivative lithocholic acid propionate can activate VDR, and Non-Patent Document 1 describes lithocholic acid acetate and lithocholic acid propionate. Patent Document 2 describes lithocholic acid derivatives with high vitamin D3 activity.

[0004] Furthermore, Patent Document 3 describes lithocholic acid amide derivatives and lithocholic acid diol derivatives. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5283043 [Patent Document 2] International Publication No. WO2017 / 131144 [Patent Document 3] International Publication No. WO2021 / 033766 [Non-patent literature]

[0006] [Non-Patent Document 1] Masuno et al, Journal of Lipid Research, Volume 54, 2013, pages 2206-2213 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] Although there have been reports of lithocholic acid derivatives with vitamin D3 activity, the existing lithocholic acid derivatives have weak affinity for the vitamin D3 receptor and have insufficient vitamin D3 activity. The lithocholic acid derivative described in Patent Document 2 has high vitamin D3 activity, but has the drawback of being rapidly eliminated from the blood in the body.

[0008] An object of the present invention is to provide a novel lithocholic acid derivative having sufficient vitamin D3 activity, as well as a medicine, a vitamin D receptor activator, and a preventive and / or therapeutic agent for vitamin D receptor-related diseases, each containing the lithocholic acid derivative. [Means for solving the problem]

[0009] As a result of intensive research to solve the above problems, the inventors discovered that lithocholic acid derivatives having a hydroxyalkyl group at the 3-position, in which a carbamate or urea group was introduced into the side chain at the 17-position, have excellent vitamin D3 activity, leading to the completion of the present invention.

[0010] According to the present invention, the following inventions are provided. [1] A compound represented by the following general formula (I), a salt thereof, or a prodrug thereof: [ka] (In the formula, R1 and R2 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms which may have a substituent. X represents -O- or -NR4-. R3 and R4 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms which may have a substituent.) [2] The compound, salt thereof, or prodrug thereof according to [1], wherein R1 and R2 are methyl. [3] The compound according to [1], a salt thereof, or a prodrug thereof, wherein X represents -O- and R3 represents methyl or ethyl. [4] The compound, salt, or prodrug thereof according to [1], wherein X represents -NR4-, and R3 and R4 each independently represent a hydrogen atom or a methyl group. [5] Any of the following compounds, their salts, or their prodrugs: [ka] [6] A pharmaceutical composition comprising the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof. [7] A vitamin D receptor activator comprising the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof. [8] A preventive and / or therapeutic agent for a vitamin D receptor-associated disease, comprising the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof.

[0011] The present invention further provides the following inventions. [9] A method for activating vitamin D receptors, comprising administering the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof to a mammal, including a human.

[10] A method for preventing and / or treating a vitamin D receptor-associated disease, comprising administering a compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof to a mammal, including a human.

[11] The compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof for use in activating a vitamin D receptor.

[12] The compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof for use in the prevention and / or treatment of a vitamin D receptor-associated disease.

[13] Use of the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof for the manufacture of a medicament.

[14] Use of the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof for the manufacture of a vitamin D receptor activator.

[15] Use of the compound according to any one of [1] to [5], a salt thereof, or a prodrug thereof for the manufacture of an agent for the prophylaxis and / or treatment of a vitamin D receptor-associated disease. [Effects of the Invention]

[0012] The compounds of the present invention are novel lithocholic acid derivatives with sufficient vitamin D3 activity. The compounds of the present invention are useful as vitamin D receptor activators and pharmaceuticals such as preventive and / or therapeutic agents for vitamin D receptor-related diseases. Furthermore, since the compounds of the present invention do not have a secosteroid skeleton, they generally have higher chemical stability than compounds with a secosteroid skeleton. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 shows the dose-response curve of the differentiation-inducing effect on HL-60 cells. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will now be described in more detail. The compound of the present invention is represented by the following general formula (1). [ka] (In the formula, R1 and R2 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms which may have a substituent. X represents -O- or -NR4-. R3 and R4 each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms which may have a substituent.)

[0015] The compound of the present invention does not have a carboxyl group in the side chain at position 17, and therefore is expected to solve the problem of rapid excretion in the body.

[0016] In this specification, the alkyl group having 1 to 8 carbon atoms may be linear, branched, cyclic, or a combination thereof. The alkyl group having 1 to 6 carbon atoms is not particularly limited, and examples thereof include methyl, ethyl, n-propyl, isopropyl, cyclopropylmethyl, n-butyl, sec-butyl, tert-butyl, cyclobutyl, cyclobutylmethyl, cyclopentyl, and cyclohexyl groups. Among these, methyl and ethyl groups are preferred, with methyl being particularly preferred. The alkyl group having 1 to 8 carbon atoms may have a substituent, and examples of the substituent include halogen (such as fluorine, chlorine, bromine, or iodine), ether, and aromatic ring. The ether or aromatic ring may be present in the middle of the alkyl chain.

[0017] Preferably, X represents -O- and R3 represents methyl or ethyl. Preferably, X represents -NR4-, and R3 and R4 each independently represent a hydrogen atom or a methyl group.

[0018] R1 and R2 may be independently the same or different groups, but are preferably the same groups. Preferably, R1 and R2 are both methyl or ethyl groups, and particularly preferably, R1 and R2 are methyl.

[0019] Specific examples of the compound of the present invention include the following compounds. [ka]

[0020] The compound represented by general formula (1) may have one or more asymmetric carbon atoms, and any optically active substance based on the asymmetric carbon atoms, stereoisomers such as diastereoisomers, any mixture of stereoisomers, racemates, etc. are all included in the scope of the present invention.

[0021] The compound represented by general formula (1) may exist in the form of a salt, such as an acid addition salt or a base addition salt, and these salts are also included within the scope of the present invention. Examples of acid addition salts include mineral acid salts such as hydrochloride, hydrobromide, sulfate, and nitrate, and organic acid salts such as p-toluenesulfonate, methanesulfonate, oxalate, tartrate, and maleate. Examples of base addition salts include metal salts such as sodium salt, potassium salt, magnesium salt, and calcium salt, and organic amine salts such as ammonium salt, triethylamine salt, and ethanolamine salt. In addition, amino acid salts such as glycine salt are also included within the scope of the present invention.

[0022] The compound represented by general formula (1) may be made into a prodrug. After administration to a living body, the prodrug becomes a pharmaceutically active compound through the action of an enzyme or metabolic hydrolysis. The prodrug may be an acid derivative known to those skilled in the art, and examples thereof include, but are not limited to, esters produced by reacting the compound represented by general formula (1) with an appropriate alcohol, amides produced by reacting the compound represented by general formula (1) with an appropriate amine, and 24-alcohols as reduced forms of carboxyl groups.

[0023] The compound represented by general formula (1), its salt, and its prodrug may exist in the form of an adduct (hydrate or solvate) with water or various solvents, and these adducts are also within the scope of the present invention. Examples of the solvent in the solvate include, but are not limited to, methanol, ethanol, acetonitrile, etc. The adduct (hydrate or solvate) may be a single one or a mixture of multiple types.

[0024] Any crystalline form of the compound represented by formula (1), its salts and prodrugs thereof also falls within the scope of the present invention.

[0025] The production methods of representative compounds encompassed by general formula (1) are described in detail and specifically in the Examples of this specification. Those skilled in the art can produce compounds encompassed by general formula (1) by appropriately selecting raw material compounds, reaction conditions, reagents, etc., and appropriately modifying or altering these methods as necessary, while referring to the specific production methods described in the Examples.

[0026] The synthesis of Compound 1a, Compound 1b, Compound 2a, and Compound 2b, which are representative compounds encompassed by General Formula (1), is not particularly limited, and can be carried out in accordance with the method described in the Examples below. Compound 4 can be obtained by dissolving Compound 3 in dehydrated dichloromethane and cooling, and then adding imidazole and chlorotrimethylsilane to cause a reaction. Compound 5 can be obtained by dissolving Compound 4 in dehydrated acetone, replacing the atmosphere with argon, cooling, and then adding triethylamine and diphenylphosphoryl azide to cause a reaction.

[0027] Compound 5 is dissolved in dehydrated toluene, dehydrated methanol is added, and the mixture is heated under reflux under argon to obtain compound 1a. Compound 1b can be obtained by dissolving compound 5 in dehydrated toluene, adding dehydrated ethanol, and heating under reflux under argon. Compound 5 is dissolved in dehydrated toluene, and aqueous ammonia is added thereto, followed by heating under reflux under argon to obtain compound 2a. Compound 5 is dissolved in dehydrated toluene, stirred under argon, and methylamine is added thereto, followed by stirring under argon to obtain compound 2b.

[0028] The compounds of the present invention can bind to and activate vitamin D receptors (VDRs). The ability of the compounds of the present invention to bind to and activate vitamin D receptors (VDRs) can be verified by assaying their cell differentiation-inducing activity on human acute promyelocytic leukemia cells, HL-60. The assay for cell differentiation induction can be performed according to the method described in "4.3.1. Assay of HL-60 cell differentiation-inducing activity" in Fujii et al. Bioorg. Med. Chem. 22 (2014) 5891-5901, as described in Test Example 1 below.

[0029] As described above, the compound of the present invention represented by formula (1) has the effect of activating VDR. Therefore, a pharmaceutical comprising the compound of the present invention represented by formula (1), a salt thereof, or a prodrug thereof as an active ingredient is useful as a vitamin D receptor activator or a vitamin D agonist. The compound of the present invention represented by formula (1), a salt thereof, or a prodrug thereof can be used as a preventive and / or therapeutic agent for vitamin D receptor-related diseases. Examples of vitamin D receptor-related diseases include, but are not limited to, rickets, osteomalacia, osteoporosis, bone diseases due to kidney damage, hypoparathyroidism, skin diseases such as psoriasis, cancers (e.g., leukemia, breast cancer, prostate cancer, colon cancer, pancreatic cancer), autoimmune diseases (e.g., rheumatoid arthritis, systemic lupus erythematosus), infectious diseases (e.g., tuberculosis), non-alcoholic steatohepatitis, and non-alcoholic fatty liver disease.

[0030] The active ingredient of the medicament, vitamin D receptor activator, and agent for preventing and / or treating vitamin D receptor-related diseases of the present invention can be a compound represented by general formula (1), a salt thereof, or a prodrug thereof. The medicament, vitamin D receptor activator, and agent for preventing and / or treating vitamin D receptor-related diseases of the present invention can be administered as the active ingredient itself, but it is generally desirable to administer the active ingredient by dispensing a pharmaceutical composition containing the active ingredient and one or more formulation additives.

[0031] The route of administration of the medicament, vitamin D receptor activator, and preventive and / or therapeutic agent for vitamin D receptor-related diseases of the present invention is not particularly limited. They may be administered orally or parenterally. Parenteral administration includes, but is not limited to, intravenous, intramuscular, subcutaneous, or intradermal injection, rectal administration, transmucosal administration, etc.

[0032] Examples of pharmaceutical compositions suitable for oral administration include tablets, capsules, powders, fine granules, granules, liquids, and syrups. Pharmaceutical compositions suitable for parenteral administration include, for example, injections, drip infusions, suppositories, inhalants, nasal drops, transdermal agents, ointments, creams, and patches.

[0033] Examples of additives that can be used for formulations include excipients, disintegrants or disintegration aids, binders, lubricants, coating agents, pigments, diluents, bases, solubilizers or solubilization aids, isotonicity agents, pH adjusters, stabilizers, propellants, and adhesives, and appropriate additives can be selected and used depending on the form of the pharmaceutical composition.

[0034] Examples of pharmaceutical additives that can be used in preparing formulations for oral administration include excipients such as glucose, lactose, D-mannitol, starch, or crystalline cellulose; disintegrants or disintegration aids such as carboxymethylcellulose, starch, or carboxymethylcellulose calcium; binders such as hydroxypropylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone, or gelatin; lubricants such as magnesium stearate or talc; coating agents such as hydroxypropylmethylcellulose, sucrose, polyethylene glycol, or titanium oxide; and bases such as petrolatum, liquid paraffin, polyethylene glycol, gelatin, kaolin, glycerin, purified water, or hard fat.

[0035] Examples of pharmaceutical additives that can be used in preparing formulations for injection or infusion include solubilizers or solubilizing aids that can constitute aqueous or ready-to-use injections, such as distilled water for injection, physiological saline, propylene glycol, and surfactants; isotonicity agents, such as glucose, sodium chloride, D-mannitol, and glycerin; and pH adjusters, such as inorganic acids, organic acids, inorganic bases, and organic bases.

[0036] The medicine, vitamin D receptor activator, and prophylactic and / or therapeutic agent for vitamin D receptor-related diseases of the present invention can be administered to mammals such as humans. The dosage of the pharmaceutical, vitamin D receptor activator, and prophylactic and / or therapeutic agent for vitamin D receptor-related diseases of the present invention should be adjusted appropriately depending on factors such as the patient's age, sex, weight, symptoms, and route of administration, but is generally in the range of about 10 μg / kg to 5000 mg / kg, and preferably about 100 μg / kg to 1000 mg / kg, of the active ingredient per day for an adult. The above-mentioned dosages may be administered once a day or in divided doses (e.g., 2 to 4 times a day).

[0037] The compound represented by general formula (1) of the present invention, its salt, or its prodrug can also be used as an experimental reagent. Vitamin D receptor activation can be achieved by treating cells, tissues, organs, or individual animals having vitamin D receptors with the compound represented by general formula (1) of the present invention, its salt, or its prodrug. Examples of cells having vitamin D receptors include, but are not limited to, cells derived from kidney, intestinal mucosa, bone marrow, bone, mammary gland, skin, and nerves. Recombinant cells obtained by introducing a vitamin D receptor gene into an established animal cell line can also be used. Examples of tissues and organs having vitamin D receptors include, but are not limited to, kidney, intestinal mucosa, bone marrow, lymphatic tissue, bone, mammary gland, skin, and nerves. Examples of individual animals include, but are not limited to, mice, rats, hamsters, rabbits, and chickens. Vitamin D receptor activation can be confirmed by, but is not limited to, measuring the induction of expression of VDR target genes (e.g., CYP24).

[0038] The present invention will be specifically explained by the following examples, but the present invention is not limited to these examples. [Example]

[0039] The abbreviations mean the following: TMCL: Chlorotrimethylsilane DPPA: Diphenylphosphoryl azide

[0040] [Synthetic scheme] [ka]

[0041] <Synthesis of Compound 4> Compound 3 (29 mg, 0.067 mmol) was dissolved in anhydrous dichloromethane (5 mL) and cooled to 0°C. Imidazole (36 mg, 0.53 mmol) and chlorotrimethylsilane (44 mg, 0.40 mmol) were added, and the mixture was stirred at room temperature for 1 hour and 30 minutes. The reaction mixture was added to saturated aqueous sodium bicarbonate and extracted with diethyl ether. The organic layer was washed with saturated brine and then dehydrated over anhydrous sodium sulfate. The solvent was evaporated to give compound 4 (32 mg, quant.) as a white solid. 1 H NMR (600 MHz, CDCl3) δ 2.40 (ddd, J = 15.6, 10.2, 5.4 Hz, 1 H), 2.26 (ddd, J = 16.5, 10.5, 5.4 Hz, 1 H), 1.96-1.92 (m, 1 H), 1.87-1.77 (m, 3 H), 1.74-1.70 (m, 1 H), 1.59-1.54 (m, 1H), 1.46-0.94 (m, 23 H), 1.22 (s, 3H), 0.92 (d, J = 6.6 Hz, 3 H), 0.90 (s, 3 H), 0.64 (s, 3 H), 0.10 (s, 9 H).

[0042] <Synthesis of Compound 5> Compound 4 (23 mg, 0.045 mmol) was dissolved in anhydrous acetone (8 mL), purged with argon, and cooled to 0 °C. Triethylamine (15 μL, 0.11 mmol) and diphenylphosphoryl azide (20 μL, 0.093 mmol) were added, and the mixture was stirred at 0 °C for 2 hours. The reaction mixture was poured into saturated brine and extracted with dichloromethane. The organic layer was dried over anhydrous sodium sulfate, and the solvent was evaporated to give crude product 5 (206 mg, 53%). This was used in the next reaction without further purification. 1H NMR (600 MHz, CDCl3) δ 2.37 (ddd, J = 14.7, 11.1, 4.8 Hz, 1 H), 2.26 (ddd, J = 15.0, 9.9, 6.6 Hz, 1 H), 1.95-1.90 (m, 1 H), 1.87-1.72 (m, 5 H), 1.59-0.94 (m, 23 H), 1.22 (s, 3H), 0.90 (d, J = 6.6 Hz, 3 H), 0.90 (s, 3 H), 0.63 (s, 3 H), 0.09 (s, 9 H).

[0043] <Synthesis of Compound 1a> Compound 5 (313 mg) was dissolved in anhydrous toluene (8 mL), anhydrous methanol (50 μL, 1.24 mmol) was added, and the mixture was heated under reflux at 90°C for 17 hours under argon. After returning to room temperature, the reaction mixture was poured into water and extracted with ethyl acetate. The organic layer was washed with saturated brine and dehydrated over sodium sulfate. After distilling off the solvent, the residue was purified by PTLC (AcOEt: n-hexane = 1:5) and recrystallized from n-hexane to obtain compound 1a (3.0 mg) as a white solid. Compound 1a: 1 H NMR (600 MHz, CDCl3) δ4.54 (br, 1 H), 3.64 (s, 3 H), 3.28-3.21 (m, 1 H), 3.12-3.06 (m, 1 H), 1.95-1.91 (m, 1 H), 1.86-1.77 (m, 3 H), 1.75-1.71 (m, 1 H), 1.60-0.95 (m, 28 H), 1.21 (s, 3 H), 0.93 (d, J = 6.6 Hz, 3 H), 0.89 (s, 3 H), 0.62 (s, 3 H); 13C NMR (150 MHz, CDCl3) δ 157.00, 71.44, 56.44, 56.06, 51.93, 51.18, 43.50, 42.68, 40.41, 40.10, 38.52, 37.38, 36.01, 35.85, 35.75, 34.93, 34.63, 33.68, 29.97, 29.93, 29.72, 28.31, 27.35, 26.40, 24.11, 23.92, 20.72, 18.53, 11.93; HRMS calcd for C29H51NNaO3 (M + Na) + 484.3766, found 484.3761.

[0044] <Synthesis of Compound 1b> Compound 5 (207 mg) was dissolved in anhydrous toluene (6 mL), anhydrous ethanol (50 μL) was added, and the mixture was heated under reflux at 70°C for 46 hours under argon (0.8563 mmol, 16.4 eq.). After returning to room temperature, the reaction mixture was poured into water and extracted with ethyl acetate. The organic layer was washed with saturated brine and dehydrated over sodium sulfate. After distilling off the solvent, the residue was purified by PTLC (AcOEt: n-hexane = 1:5) and recrystallized from n-hexane to obtain compound 1b (4.4 mg) as a white solid. Compound 1b: 1 H NMR (600 MHz, CDCl3) δ4.53 (br, 1 H), 4.1 (q, J = 7.2, 6.6 Hz, 2 H), 3.28-3.21 (m, 1 H), 3.12-3.06 (m, 1 H), 1.95-1.91 (m, 1 H), 1.86-1.77 (m, 3 H), 1.75-1.71 (m, 1 H), 1.60-0.95 (m, 31 H), 1.22 (s, 3 H), 0.93 (d, J = 6.6 Hz, 3 H), 0.90 (s, 3 H), 0.63 (s, 3 H); 13C NMR (150 MHz, CDCl3) δ 159.99, 71.67, 60.60, 56.50, 56.12, 51.24, 49.35, 43.56, 42.74, 40.46, 40.16, 37.43, 36.06, 35.90, 35.81, 34.98, 34.69, 33.74, 30.02, 29.99, 29.77, 28.36, 27.41, 26.46, 24.16, 23.97, 20.77, 18.58, 14.67, 11.98; HRMS calcd for C30H53NNaO3 (M+ Na) + 498.3906, found 498.3918.

[0045] <Synthesis of Compound 2a> Compound 5 (313 mg) was dissolved in anhydrous toluene (8 mL), 28% aqueous ammonia (0.5 mL) was added, and the mixture was heated to reflux at 70°C for 21 hours under argon. After returning to room temperature, the reaction mixture was poured into water and extracted with ethyl acetate. The organic layer was washed with saturated brine and dehydrated over sodium sulfate. After distilling off the solvent, the residue was purified by flash silica gel column chromatography (CHCl3:MeOH = 100:1) and recrystallized from ethanol and n-hexane to obtain compound 2a (9.8 mg) as a white solid. Compound 2a: 1 H NMR (600 MHz, DMSO-d6) δ5.77 (br, 1H), 5.29 (br, 2H), 3.04-2.99 (m, 1 H), 2.88-2.82 (m, 1 H), 1.92-1.89 (m, 1 H), 1.82-1.74 (m, 3 H), 1.69-1.66 (m, 1 H), 1.53-0.90 (m, 25 H), 1.06 (s, 6 H), 0.87 (d, J = 6.0 Hz, 3 H), 0.88 (s, 3 H), 0.61 (s, 3 H);

[0046] <Synthesis of Compound 2b> The crude product containing compound 5 (206 mg) was dissolved in anhydrous toluene (6 mL) and stirred at 65 °C under argon for 1 hour. After returning to room temperature, methylamine (40% methanol solution, 10 μL, 0.2901 mmol, 12.1 eq.) was added and the mixture was stirred under argon for 17.5 hours. After returning to room temperature, the reaction mixture was poured into water and extracted with ethyl acetate. The organic layer was washed with saturated brine and dehydrated over sodium sulfate. After distilling off the solvent, the residue was purified by silica gel column chromatography (CHCl:MeOH = 25:1) and recrystallized from ethanol and n-hexane to give compound 2b (3.3 mg, 0.007168 mmol, 30%) as a white solid. Compound 2b: 1 H NMR (600 MHz, MD3OD) δ3.10-3.06 (m, 1 H), 2.95-2.91 (m, 1 H), 2.57 (s, 3 H), 1.92-1.88 (m, 1 H), 1.82-1.74 (m, 3 H), 1.70-1.66 (m, 1 H), 1.55-0.88 (m, 25 H), 1.08 (s, 6 H), 0.86 (d, J = 6.6 Hz, 3 H), 0.84 (s, 3 H), 0.58 (s, 3 H); 13 C NMR (150 MHz, MD3OD) δ 147.13, 72.00, 68.35, 61.91, 57.94, 57.72, 56.35, 52.07, 45.13, 43.91, 41.88, 41.56, 38.67, 37.45, 37.25, 36.20, 35.80, 35.04, 30.98, 29.91, 29.89, 29.39, 28.61, 27.73, 25.27, 24.52, 21.91, 19.10, 12.41; HRMS calcd for C29H52N2NaO2 (M + Na) + 483.3923, found 483.3921.

[0047] Test Example 1: Cell differentiation induction assay in HL-60 cells The cell differentiation-inducing activity of compound 1a and compound 1b of Example 1 on human acute promyelocytic leukemia cell line HL-60 was examined. Active vitamin D3 was used for comparison.

[0048] The assay for cell differentiation induction was performed in the same manner as described in "4.3.1. Assay of HL-60 cell differentiation-inducing activity" in Fujii et al. Bioorg. Med. Chem. 22 (2014) 5891-5901. Specifically, the assay was as follows.

[0049] HL-60 cells were cultured in RPMI-1640 medium supplemented with 5% FBS (fetal bovine serum), penicillin G, and streptomycin at 37°C and 5% CO. Cells were grown at a density of 8.0 × 10 cells / mL in RPMI-1640 (5% FBS). 4 Dilute the test compound in ethanol to a final concentration of 10 cells / mL. -10 ~10 -5 Ethanol was added to the cells at a concentration of 1000 M. Control cells were treated with the same volume of ethanol alone. 1α,25-dihydroxyvitamin D3 was assayed simultaneously as a positive control. Cells were incubated at 37°C and 5% CO2 for 4 days. The percentage of differentiated cells was determined by measuring the reduction potential of nitroblue tetrazolium (NBT). Cells were incubated for 20 minutes at 37°C in an equal volume of RPMI-1640 (5% FBS) and phosphate-buffered saline (PBS) containing NBT (0.2%) and 12-O-tetradecanoylphorbol 13-acetate (TPA; 200 ng / mL). The percentage of cells containing blue-black formazan was determined in a minimum of 200 cells. The percentage (%) of differentiated cells calculated from the NBT reducing activity is shown in FIG.

[0050] As can be seen from the results in FIG. 1, Compounds 1a and 1b of the present invention have a strong differentiation-inducing effect on HL-60 cells, similar to active vitamin D3.

Claims

1. A compound represented by the following general formula (I), or a salt thereof: 【Chemistry 1】 (In the formula, R １ and R ２ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; X represents —O— or —NR ４ Indicates -. ３ and R ４ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

2. R １ and R ２ The compound according to claim 1, or a salt thereof, wherein is methyl.

3. X represents —O—, and R ３ The compound according to claim 1, or a salt thereof, wherein represents methyl or ethyl.

4. X is -NR ４ - indicates R ３ and R ４ The compound according to claim 1 , or a salt thereof, wherein each independently represents a hydrogen atom or a methyl group.

5. Any of the following compounds or salts thereof: 【Chemistry 2】

6. A medicament comprising the compound according to any one of claims 1 to 5 or a salt thereof.

7. A vitamin D receptor activator comprising the compound according to any one of claims 1 to 5 or a salt thereof.

8. A preventive and / or therapeutic agent for a vitamin D receptor-associated disease, comprising the compound according to any one of claims 1 to 5 or a salt thereof.

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