Use of tetrahydronaphthyridine derivatives for producing products for improving pigmentation

Abstract

The present invention provides the use of a compound represented by formula I, a pharmaceutically acceptable salt, hydrate, isomer, prodrug, or a mixture thereof, for manufacturing a product for improving pigmentation. This compound is very promising for the treatment of melasma. [Chemical 1] JPEG2025518798000031.jpg31169

Description

Detailed Description of the Invention

[0001] This invention claims the priority of a prior application filed with the State Intellectual Property Office of China on May 30, 2022, with a patent application number of 202210597120.9 and an invention title of "Use of Tetrahydronaphthyridine Derivatives for Producing Products for Improving Pigmentation". All the contents of the prior application are incorporated herein by reference.

[0002] 〔Technical Field〕 This invention relates to the field of chemistry, specifically to the use of tetrahydronaphthyridine derivatives for producing products for improving pigmentation, and more specifically to the use of tetrahydronaphthyridine derivatives for producing products for improving melasma.

[0003] 〔Background Art〕 Skin pigmentation is a difficult disease in dermatology. For example, melasma, senile lentigo, freckles, melanosis, facial nevus, and birthmarks not only affect appearance but also have a profound impact on people's life experiences. With the daily improvement of people's living standards, whitening, removing stains, and improving skin pigmentation have gradually become the common pursuit of people and are also the treatment needs of many dermatological diseases.

[0004] Melasma is a very common chronic, acquired facial skin disease with increased melanin, and increased pigmentation is its main feature. Melasma mostly occurs in middle-aged women. The main symptoms are symmetrically distributed patches of dark brown or yellowish-brown with different shades and unclear boundaries on the cheeks, forehead, and lower jaw, and it is also called chloasma or butterfly-shaped macule. Melasma usually has no subjective symptoms and does not require treatment, but it has a profound impact on appearance and causes double damage to the patient's body and mind. With the improvement of living standards, people have attached more importance to appearance, and the treatment of skin diseases such as melasma has also received increasing attention.

[0005] At present, the pathogenesis of melasma is not yet fully clear. According to many studies, genetic susceptibility, ultraviolet irradiation, endocrine dysfunction, skin barrier dysfunction, changes in hormone levels, mental factors, and nutritional levels are all closely related to the occurrence of melasma. In the actual treatment process, due to the different areas, severities, and pigmentation degrees of melasma in different patients, clinically, the skin lesions of patients' melasma are usually classified and typed to formulate a comprehensive treatment plan. Currently, the drug treatment methods for melasma include topical medications and systemic medications.

[0006] Topical medications generally are based on two aspects: protecting or restoring the skin barrier function with functional skin care products, and using topical medications mainly for epidermal melasma to inhibit and remove melanin at the skin lesion sites of melasma. A typical drug is hydroquinone. Hydroquinone can inhibit the synthesis of melanocyte DNA and RNA, competitively bind to tyrosinase, inhibit the formation of melanosomes, or accelerate their decomposition. The higher the use concentration, the stronger the depigmentation effect, but the irritation to the skin is also greater, with a burning sensation and occasionally a local allergic reaction may occur. The commonly used concentration of hydroquinone is 2% - 5%. In 2002, the FDA approved that the triple combination cream (TCC) consisting of 4% hydroquinone, 0.01% fluocinonide, and 0.05% tretinoin can be used for the treatment of melasma, and it is currently the first-choice drug for melasma treatment. However, due to many side effects, the use of TCC should not exceed half a year.

[0007] The most representative drug for systemic use is tranexamic acid (TXA). Tranexamic acid is a plasmin inhibitor. In recent years, it has shown good effects in the treatment of melasma in the forms of oral administration, topical application, and topical microneedle injection, and it has been found that it can improve melasma. Tranexamic acid inhibits plasmin, thereby reducing α-melanocyte-stimulating hormone (α-MSH), decreasing melanin production, competitively inhibiting tyrosinase activity in melanosomes, and achieving the effect of lightening pigmented spots. At the same time, tranexamic acid inhibits angiogenesis and can reduce erythema; there is also research suggesting that the improvement of melasma by tranexamic acid is related to its ability to inhibit the expression of endothelin-1 (ET-1). There are also certain side effects in the use of tranexamic acid for melasma. Headache and severe abdominal distension caused by oral TXA have been reported, and patients cannot tolerate it, so they abandon the treatment. Adverse reactions such as erythema and a burning sensation occur due to topical TXA use.

[0008] Currently, there are many options for improving melasma, but their effects are not particularly ideal. The administration period is very long, the administration frequency is relatively high, and it is difficult to meet the increasing clinical needs. Developing safer and more effective products for pigmentation is a current concern.

[0009] 〔Summary of the Invention〕 One object of the present invention is to provide the use of a compound represented by formula I, its pharmaceutically acceptable salt, hydrate, isomer, prodrug, or a mixture thereof for manufacturing a product for improving pigmentation.

[0010]

Chemical formula

[0011] However, R1 is selected from a carboxyl group, a phosphate group, and a sulfonic acid group; R2 is selected from hydrogen, a substituted or unsubstituted amino group, a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C1-C6 alkoxy group, a C1-C4 haloalkyl group, a substituted or unsubstituted C3-C6 cycloalkyl group, a substituted or unsubstituted 4-8 membered aliphatic heterocyclic group, a substituted or unsubstituted 6-10 membered aryl group, and a substituted or unsubstituted 6-10 membered aromatic heterocyclic group.

[0012] In a specific embodiment, R2 is hydrogen, an unsubstituted or optionally substituted by one or two or more R 2a substituted amino group, C1-C6 alkyl group, C1-C6 alkoxy group, C1-C4 haloalkyl group, C3-C6 cycloalkyl group, 4-8 membered aliphatic heterocyclic group, 6-10 membered aryl, 6-10 membered aromatic heterocyclic group selected from.

[0013] In a specific embodiment, the R 2a is selected from halogen, OH, NH2, NO2, CN, oxo (=O), C1-C6 alkyl group, C1-C6 alkoxy group, C3-C6 cycloalkyl group, 4-8 membered aliphatic heterocyclic group, 6-10 membered aryl group, and 6-10 membered aromatic heterocyclic group.

[0014] In a specific embodiment, the R2 is hydrogen, an unsubstituted or optionally substituted by one or two or more R 2a substituted phenyl group, phenyl-C1-C6 alkyl- selected from.

[0015] In a specific embodiment, the R2 is hydrogen,

[0016]

Chemical formula

[0017] selected from.

[0018] In a specific embodiment, the pigmentation may be a disease associated with pigmentation, and the disease associated with pigmentation is a disease caused by the deposition of melanin on the surface of the skin, including chloasma, senile plaque, freckles, melanoma, facial mole, birthmark, etc.

[0019] In a specific embodiment, the disease associated with the pigmentation is chloasma.

[0020] In a specific embodiment, the compound of formula I is selected from the compounds of the following chemical structures, their pharmaceutically acceptable salts, hydrates, isomers, prodrugs or mixtures:

[0021]

Chemical formula

[0022] In a specific embodiment, the pharmaceutically acceptable salt is the hydrochloride salt of the compound of formula I.

[0023] In a specific embodiment, the product for improving the pigmentation may be a pharmaceutical or a cosmetic.

[0024] In a specific embodiment, the product for improving the pigmentation refers to a clinically available pharmaceutical preparation produced with at least one of the compound of formula I, its pharmaceutically acceptable salt, hydrate, isomer, prodrug as an active ingredient and one or more pharmaceutically acceptable excipients. The pharmaceutical preparation according to the present invention can be produced and used in the form of oral preparations, external preparations, injections, etc.

[0025] 〔Advantages of the Invention〕 The present invention adopts a model in which melasma in rats is induced by 280 - 320 nm UVB irradiation + progesterone injection, and is administered by local injection, and the action effects of the compound are evaluated by appearance indexes, histopathological examinations, biochemical indexes, etc. According to the results, the compound of formula I of the present invention can effectively reduce the quantity of melanin granules in the skin surface cells of the rat modeling area of the melasma model, improve the skin tissue structure morphology and inflammatory cell infiltration phenomenon, effectively reduce the level of melasma-related biochemical indexes, and has very good application prospects for the treatment of melasma.

[0026] 〔Brief Description of Drawings〕 Figure 1 shows the effects of tranexamic acid and the test compound group on the model of inducing melasma in rats by ultraviolet irradiation + progesterone injection. Among them, (A) is the overall situation of the skin of the rat test group; (B) is the HE staining situation of the skin tissue of each group; (C) is the distribution situation of the epidermal basal layer and basal layer melanin granules of each group; (D) is the expression situation of skin tissue tyrosinase of each group; (E) is the observation grade of the appearance index of the melasma model; (F) is the grade of the content of melanin granules of the melasma rat model after collecting skin tissue on the 58th day; (G) is the average integrated optical density distribution of epidermal tyrosinase of each group after collecting skin tissue on the 58th day; (H) is the content situation of ET-1 in the skin tissue homogenate supernatant of each group after collecting the skin tissue homogenate supernatant of rats in each group on the 58th day; (I) is the weight change situation of rats in each group during the experimental period (Day1 - Day58). All score and count results were obtained by double-blind method. Compared with the control group, ***P < 0.001, compared with the model group, #P < 0.05, ##P < 0.01, P < 0.001.

[0027] <Definition and Explanation of Terms> Unless otherwise specified, the definitions of the groups and terms described in this specification and the claims can be arbitrarily combined and joined with each other, including their definitions by way of example, exemplary definitions, preferred definitions, definitions listed in tables, definitions of specific compounds in the examples, etc. The definitions of such combinations and joined groups and the compound structures should be understood to be within the scope described in the specification and / or claims of this application.

[0028] Unless otherwise specified, the numerical ranges described in this specification and the claims correspond to those that list each specific integer value. For example, the numerical range "1 to 40" corresponds to each integer value in the numerical range "1 to 10", i.e., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and each integer value in the numerical range "11 to 40", i.e., 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40. Also, when a numerical range is defined as a "number", it should be understood that the two endpoints of the range, each integer within the range, and each decimal within the range are described. For example, "a number from 0 to 10" should be understood to describe not only each integer of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, but also each integer is described as the sum of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 respectively.

[0029] In this specification, when explaining 1, 2 or more, "more" should be understood to mean an integer greater than 2, for example, an integer of 3 or more, such as 3, 4, 5, 6, 7, 8, 9 or 10.

[0030] The term "halogen" means fluorine, chlorine, bromine and iodine.

[0031] The term "C1-C6 alkyl group" means a straight-chain or branched-chain alkyl group having 1, 2, 3, 4, 5 or 6 carbon atoms. Examples of said alkyl group include, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a 2-methylbutyl group, a 1-methylbutyl group, a 1-ethylpropyl group, a 1,2-dimethylpropyl group, a neopentyl group, a 1,1-dimethylpropyl group, a 4-methylpentyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 1-methylpentyl group, a 2-ethylbutyl group, a 1-ethylbutyl group, a 3,3-dimethylbutyl group, a 2,2-dimethylbutyl group, a 1,1-dimethylbutyl group, a 2,3-dimethylbutyl group, a 1,3-dimethylbutyl group, a 1,2-dimethylbutyl group, etc., or isomers thereof.

[0032] The term "alkoxy group" means -O-(alkyl), where the definition of the alkyl group is as described above. Non-limiting examples of alkoxy groups include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

[0033] The term "C3-C6 cycloalkyl group" should be understood to mean a saturated monovalent monocyclic hydrocarbon ring having 3, 4, 5 or 6 carbon atoms. C 3-10 The cycloalkyl group may be a monocyclic hydrocarbon group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc.

[0034] The term "4- to 8-membered aliphatic heterocyclic group" means a saturated ring or ring system, unless otherwise defined. For example, it can be a 4-membered, 5-membered, 6-membered or 7-membered monocyclic ring, or a 7-membered or 8-membered bicyclic ring (e.g., a fused ring, a bridged ring, a spiro ring), and contains at least 1, for example, 1, 2, 3, 4, 5 or more heteroatoms selected from O, S and N. Here, N and S may optionally be oxidized to various oxidation states so as to form a nitrogen oxide, -S(O)- or -S(O)2- state. The aliphatic heterocyclic group may be bonded to the rest of the molecule via any one of the carbon atoms or a nitrogen atom (if present). The aliphatic heterocyclic group may include rings of fused or bridged rings and spiro rings. In particular, examples of the aliphatic heterocyclic group include 4-membered rings such as an azetidinyl group and an oxetanyl group, 5-membered rings such as a tetrahydrofuryl group, a dioxolanyl group, a pyrrolidinyl group, an imidazolyl group, a pyrazolyl group, a pyrrolidinyl group, 6-membered rings such as a tetrahydropyranyl group, a piperidinyl group, a morpholinyl group, a dithioalkyl group, a thiomorpholinyl group, a piperazinyl group, a trithioalkyl group, 7-membered rings such as a diazacycloheptyl group, but are not limited thereto.

[0035] The term "6- to 10-membered aryl group" preferably means a monocyclic or bicyclic monovalent aromatic or partially aromatic ring having 6, 7, 8, 9 or 10 carbon atoms, particularly a ring having 6 carbon atoms ("C6 aryl group"), such as a phenyl group, or a biphenyl group, or a ring having 9 carbon atoms ("C9 aryl group"), such as an indanyl group or an indenyl group, or a ring having 10 carbon atoms ("C 10 aryl group"), such as a tetrahydronaphthyl group, a dihydronaphthyl group or a naphthyl group. When the 6- to 10-membered aryl group is substituted, it can be mono-substituted or multi-substituted. Also, the substitution site is not limited, and for example, it may be ortho-substituted, para-substituted or meta-substituted.

[0036] The term "6- to 10-membered aromatic heterocyclic group" is to be understood as including a monovalent monocyclic or bicyclic (e.g., fused ring, bridged ring, spiro ring) aromatic ring system having 6 to 10 ring atoms and containing 1 to 5 heteroatoms independently selected from N, O, and S, preferably 1 to 3 heteroatoms independently selected from N, O, and S. The term "heteroaryl group" also means a group in which a heteroaromatic ring is fused to one or more aryl groups, alicyclic or heterocyclic rings, and the attached group or point is on the heteroaromatic ring, and is, for example, selected from a pyridyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, and a pyranyl group.

[0037] [Mode for Carrying Out the Invention] Hereinafter, the technical solution of the present invention will be described in more detail in combination with specific examples. It should be understood that the following examples are merely illustrative of the present invention and do not limit the protection scope of the present invention. The technology realized based on the above content of the present invention is included within the protection scope of the present invention.

[0038] Unless otherwise specified, all raw materials and reagents used in the following examples are commercially available or can be produced by known methods.

[0039] 1. Experimental Purpose The therapeutic effect of the compound of the present invention on a rat liver spot model was measured.

[0040] 2. Experimental Materials and Equipment

[0041] [Table 1]

[0042] [Table 2]

[0043] 3. Experimental Method 3.1 Molding: Before the start of the experiment, on Day 0, SD rats (purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd., SPF grade, female, 7 - 8 weeks old, body weight 200 ± 20 g) were randomly grouped and numbered. First, the back hair of the animals in each group was shaved using an electric shaver, and then, depilatory cream was used to remove the short hair on the skin, fully exposing the back skin. The depilation area was slightly larger than the area of the actual molding region (5 cm × 5 cm). Each rat was depilated every 2 - 3 days to ensure complete exposure of the back skin. The next day (Day 1), the rats in each group were weighed, and the body weight was recorded after the reading of the electronic scale stabilized. Progesterone injection was intramuscularly injected into the groin of the rats (alternately on both sides of the thighs). The drug concentration was 20 mg / mL, the injection dose was 25 mg / kg, once a day. After intramuscular injection, ultraviolet light with a wavelength of 280 - 320 nm was irradiated on the back skin of the rats. The light source was about 30 cm away from the back skin of the rats, for 60 minutes each time, lasting for a total of 4 weeks.

[0044] 3.2 Administration: After rat molding, tranexamic acid of the positive control group with a concentration of 5 mg / mL and the test compound injection solution with concentrations of 5 and 1.5 mg / mL (the solvent was physiological saline) were multi - point injected into the skin damage site with a 30G insulin needle. The administration volume was 0.05 mL / cm 2 , 5 days / time, continuously administered for 30 days. The control group (only depilated, without molding treatment) and the model group were administered the solvent.

[0045] 3.3 Detection indicators: The first molding day was set as Day1, and the experimental period was continued for 58 days. After the experiment ended (Day58), 1 hour after the last administration, the skin of the molding area of the rats in each group was photographed and used for apparent index scoring (see Table 1 for the scoring criteria). Then, the rats in each group were euthanized, their backs were depilated, 0.5 g of the full-thickness skin tissue at the depilated site on the back was taken, physiological saline was added in an ice bath to prepare a 10% tissue homogenate, the homogenate solution was centrifuged at 3000 r / min at room temperature for 10 minutes, the supernatant of the skin tissue homogenate was obtained, and the expression of endothelin-1 in the supernatant of the skin tissue homogenate of the rats was detected by ELISA; the skin of the molding area on the back of the rats was taken and immersed in 10% neutral formaldehyde and fixed at room temperature for 4 days. Four days later (Day62), paraffin embedding and sectioning were performed to obtain paraffin sections of the skin of the rats in each group, and HE staining was used to observe the pathological changes of the skin tissues of the rats in each group. Staining method: Ordinary xylene dewaxing was performed on the dried paraffin sections, gradient ethanol hydration was performed, and distilled water washing was done; the nuclei were stained with hematoxylin for 2 minutes, differentiated with hydrochloric acid and alcohol for several seconds, and washed with water to turn blue; the stained sections were stained with eosin staining solution for 1 minute, and washed with water to wash off the residual staining solution; the sections were dehydrated and dried with gradient alcohol, cleared with xylene, sealed with neutral rubber, and then microscopic examination was performed. ° The hyperplasia of the epidermis, the arrangement of basal cells, the presence or absence of inflammatory cell infiltration into the dermis layer, and the change in the number of capillaries in the skin tissue sample sections of each group were observed according to the evaluation indicators. Fontana-Masson staining was used to observe the skin pigmentation of the rats in each group. Experimental method: After dewaxing and hydrating the sections, the sections were immersed in Fontana silver nitrate solution and incubated in a 56 °C incubator in the dark for 30 - 40 minutes; washed with distilled water 5 - 6 times, 1 - 2 minutes each time; treated with hypo solution for 1 - 5 minutes; rinsed with tap water for 3 - 5 minutes; counterstained with neutral red dye for 5 minutes; rinsed with tap water for 1 minute; dehydrated with 95% ethanol and absolute ethanol, cleared with xylene, sealed with neutral rubber, and then microscopic examination was performed. The distribution status of melanin particles was scored (see Table 2 for the scoring criteria). The expression of tyrosinase in the skin of each group was detected immunohistochemically.Experimental method: 1) Single baking: Put the prepared paraffin sections into an electrothermal constant temperature drying oven and bake at 60°C for 3 hours; 2) Perform normal xylene dewaxing on the dried paraffin sections, perform ethanol hydration with a decreasing gradient, and wash with distilled water; 3) Perform antigen retrieval; 4) Drop 3% H2O2 and incubate at room temperature for 10 minutes to inactivate the endogenous enzyme, and wash 3 times with PBS for 3 minutes each time; 5) Drop normal goat immune serum on each section for blocking, incubate at room temperature for 10 minutes, then shake off the excess liquid, without washing, dilute the tyrosinase antibody (1:50) at a certain ratio and drop it, and refrigerate overnight in a 4°C refrigerator; 6) After taking out from the refrigerator and returning to room temperature, wash 3 times with PBS for 3 minutes each time; 7) Drop the polymer enhancer (reagent A) on each section, wash 3 times with PBS for 3 minutes each time at room temperature for 20 minutes; 8) Drop the enzyme-labeled anti-mouse rabbit polymer (reagent B) on each section, wash 3 times with PBS for 3 minutes each time at room temperature for 10 minutes; 9) DAB color development, control the reaction time under the microscope, perform hematoxylin counterstaining, wash thoroughly with distilled water, and stop the color development; 10) Dehydrate and dry the sections with gradient alcohol, clarify with xylene, and seal with neutral gum; 11) Take pictures at 200× magnification using a phase contrast microscope. The area of the tyrosinase positive region (stained region) and the integrated optical density value were measured using ImageJ (1.8.0) software, and the average optical density value was calculated by the formula AOD = IOD / Area.

[0046]

Table 3

[0047]

Table 4

[0048] 3.4 The experimental data were expressed as means ± SD. The statistical differences between groups were analyzed using one-way ANOVA and Tukey's test, and the scoring data were analyzed statistically using the Mann-Whitney U test. A significant difference was recognized when the P value was less than 0.05.

[0049] 3.5 Preparation of Test Compounds Production Example 1

[0050]

Chem.

[0051] Step 1: Preparation of tert-Butyl 2-Chloro-7,8-Dihydro-1,6-Naphthyridine-6(5H)-Carboxylate 2-Chloro-5,6,7,8-tetrahydro-1,6-naphthyridine hydrochloride (0.9 g) was weighed and suspended in dichloromethane (15 mL). After liberating N,N-diisopropylethylamine (1.4 g), di-tert-butyl dicarbonate (1.15 g) was added and the mixture was reacted at room temperature for 1 hour. TLC indicated complete consumption of the starting material, and the title compound (1.12 g) was obtained by column chromatography.

[0052]

Chem.

[0053] MS(ESI) m / z (M+H) + = 269.0.

[0054] Step 2: Preparation of tert-Butyl 2-Cyano-7,8-Dihydro-1,6-Naphthyridine-6(5H)-Carboxylate tert-Butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (1.12 g) was weighed and dissolved in N,N-dimethylformamide (20 mL). Zinc cyanide (2.44 g) and tetrakis(triphenylphosphine)palladium (483 mg) were added. The mixture was purged with argon three times and reacted at 120 °C for 3 hours. TLC indicated complete consumption of the starting material. Ethyl acetate was added for dilution, and the mixture was filtered through diatomaceous earth, extracted twice with ethyl acetate, washed once with saturated brine, dried over anhydrous sodium sulfate, and purified by column chromatography to obtain the title compound (1.1 g).

[0055]

Chem.

[0056] MS(ESI) m / z (M+H)+ = 260.0.

[0057] Step 3: Preparation of 5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride tert-Butyl 2-cyano-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (1.1 g) was weighed and dissolved in 6 M aqueous hydrochloric acid (25 mL), and reacted at 120 °C overnight. LCMS indicated that the raw material was completely consumed, and the reaction solution was concentrated until dry, and 5,6,7,8-tetrahydro-1,6-naphthyridine-2-carboxylic acid hydrochloride (test compound 1, 726 mg) was obtained by separation by pre-HPLC.

[0058]

Chem.

[0059] MS(ESI) m / z (M+H)+ = 179.0.

[0060] 1 1H NMR (400 MHz, Methanol-d4) δ 8.21 (d, J = 8.1 Hz, 1H), 8.12 (d, J = 8.0 Hz, 1H), 4.60 (s, 2H), 3.71 (t, J = 6.4 Hz, 2H), 3.42 (t, J = 6.4 Hz, 2H).

[0061] Production Example 2 Step 1: Preparation of tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate

[0062]

Chem.

[0063] 2-Chloro-5,6,7,8-tetrahydro-1,6-naphthyridine hydrochloride (0.9 g) was suspended in dichloromethane (15 mL), N,N-diisopropylethylamine (1.4 g) was added, and then di-tert-butyl dicarbonate (1.15 g) was added, and the mixture was reacted at room temperature for 1 hour. TLC indicated that the raw material was completely consumed. The reaction solution was diluted with water, extracted with dichloromethane, the organic phases were combined, dried over anhydrous sodium sulfate, filtered, concentrated, and the obtained crude product was purified by column chromatography to obtain the target compound (1.12 g). MS(ESI) m / z (M+H)+ = 269.0.

[0064] Step 2: Preparation of tert-butyl 2-(diethoxyphosphoryl)-7,8-dihydro-1,6-naphthylpyridine-6(5H)-carboxylate

[0065]

Chemical formula

[0066] Under an argon atmosphere, tert-butyl 2-chloro-7,8-dihydro-1,6-naphthyridine-6(5H-carboxylate (100 mg) was dissolved in toluene (20 mL), diethyl phosphite (102 mg), tris(dibenzylideneacetone)dipalladium (34 mg), 1,1'-bis(diphenylphosphino)ferrocene (41 mg) and triethylamine (75 mg) were added, and the system was reacted at 120 °C overnight. TLC indicated that the raw material was completely consumed. Ethyl acetate was added for dilution, diatomaceous earth was added for filtration, the filtrate was collected and concentrated, and the crude product was purified by Preparative°TLC to obtain the target compound (70 mg). MS(ESI) m / z (M+H)+ = 371.1.

[0067] Step 3: Preparation of (5,6,7,8-tetrahydro-1,6-naphthyridin-2-yl)phosphonic acid hydrochloride (Test Compound 2)

[0068] [Chemical formula]

[0069] tert-Butyl 2-(diethoxyphosphoryl)-7,8-dihydro-1,6-naphthylpyridine-6(5H)-carboxylate (70 mg) was dissolved in concentrated hydrochloric acid (5 mL) and reacted at 100 °C overnight. LCMS indicated that the raw material was completely consumed. The reaction solution was concentrated, and the crude product was purified by pre-HPLC to obtain the target compound (30 mg). MS(ESI) m / z (M+H)+ = 215.0.

[0070] 1 1H NMR (400 MHz, D2O) δ 8.35 (dd, J = 8.0, 2.4 Hz, 1H), 8.06 (t, J = 7.7 Hz, 1H), 4.59 (s, 2H), 3.67 (t, J = 6.0 Hz, 2H), 3.49 (t, J = 6.4 Hz, 2H).

[0071] Production Example 3 (1) Production of 2-methyl-N-(4-phenylbutylene)propane-2-sulfenamide 4-Phenylbutanol (7.6 mL) was dissolved in dichloromethane (200 mL), and 2-iodobenzoylbenzoic acid (28.00 g), tert-butylsulfenamide (9.07 g), anhydrous magnesium sulfate (30.80 g), and pyridinium 4-methylbenzenesulfonate (0.627 g) were added sequentially. The mixture was heated to 40 °C, reacted for 24 hours, cooled to room temperature, suction filtered, the filter cake was washed with dichloromethane, the filtrate was concentrated until dry, and purified by column chromatography to obtain the title compound (5.1 g).

[0072] [Chemical formula]

[0073] MS(ESI) m / z (M+H)+ = 252.1.

[0074] (2) Preparation of N-(1-(3-bromo-6-methoxypyridin-2-yl)-5-phenylpentan-2-yl)-2-methylpropane-2-sulfenamide 3-Bromo-6-methoxy-2-methylpyridine (4.85 g) was weighed into a dry reaction flask, anhydrous tetrahydrofuran (100 mL) was injected under a nitrogen atmosphere, and the mixture was cooled to -78 °C. A solution of lithium diisopropylamide in tetrahydrofuran (12.00 mL, 2.0 M) was added dropwise, and the reaction was carried out at -78 °C for 40 minutes. Tetrahydrofuran (20 mL) containing 2-methyl-N-(4-phenylbutylene)propane-2-sulfenamide (5.02 g) was added dropwise, the reaction was carried out at -30 °C for 30 minutes, and the temperature was slowly raised to room temperature. LCMS detected that the reaction was complete, saturated ammonium chloride solution was added to quench, ethyl acetate and water were added, liquid separation was carried out, extraction was performed, and the organic phase was concentrated until dry. Purification by column chromatography gave the title compound (7.15 g).

[0075]

Chemical Structure

[0076] MS(ESI) m / z (M+H) + = 453.1, 455.1.

[0077] (3) Preparation of ethyl 2-(2-((tert-butylsulfinyl)amino)-5-phenylpentyl)-6-methoxynicotinate N-(1-(3-Bromo-6-methoxypyridin-2-yl)-5-phenylpentan-2-yl)-2-methylpropane-2-sulfenamide (5.42 g) was weighed and dissolved in ethanol (150 mL). After adding [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloromethane dichloride complex (0.979 g) and N,N-diisopropylethylamine (4.12 mL), the system was purged with carbon monoxide, and the reaction was carried out overnight under reflux in a carbon monoxide atmosphere, and the solvent was removed under reduced pressure. Purification by column chromatography gave the title compound (2.01 g).

[0078] [Chem.]

[0079] MS(ESI) m / z (M + H) + = 447.2.

[0080] (4) Preparation of 2 - methoxy - 7 - (3 - phenylpropyl) - 7,8 - dihydro - 1,6 - naphthyridin - 5(H) - one Ethyl 2-(2 - ((tert - butylsulfinyl)amino)-5 - phenylpentyl)-6 - methoxynicotinate (2.00 g) was weighed and dissolved in acetonitrile (50 mL), and cesium carbonate (5.87 g) was added. The temperature was raised to 80 °C and stirred overnight, and LC - MS was used to monitor the completion of the reaction. After cooling to room temperature, suction filtration was carried out, the filter cake was washed with dichloromethane, the filtrate was concentrated until dry, and purified by column chromatography to obtain the title compound (1.1 g).

[0081] [Chem.]

[0082] MS(ESI) m / z (M + H) + = 297.1.

[0083] (5) Preparation of 2 - methoxy - 7 - (3 - phenylpropyl) - 5,6,7,8 - tetrahydro - 1,6 - naphthyridine 2-Methoxy-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthyridin-5(6H)-one (1.10 g) was weighed and dissolved in tetrahydrofuran (70 mL). Lithium aluminum hydride (0.562 g) was added under an ice bath, and the mixture was stirred at 70 °C for 8 hours. LC-MS was used to monitor the completion of the reaction. Under the ice bath, water (0.56 mL), sodium hydroxide solution (15%, 0.56 mL), and water (1.68 mL) were sequentially added dropwise. After stirring at room temperature for 20 minutes, it was dried over anhydrous magnesium sulfate, suction filtered, the filter cake was washed with dichloromethane, and concentrated under reduced pressure until dry. It was purified by column chromatography to obtain the title compound (0.41 g).

[0084]

Chem.

[0085] MS(ESI) m / z (M+H) + = 283.2.

[0086] (6) Preparation of 7-(3-phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridin-2-ol 2-Methoxy-7-(3-phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine (0.40 g) was weighed, acetic acid solution of hydrobromic acid (5 mL) was added, the temperature was raised to 80 °C and stirred for 5 hours, the solvent was removed under reduced pressure, ethyl acetate was added and triturated, filtered, and dried to obtain the title compound (0.295 g).

[0087]

Chem.

[0088] MS(ESI) m / z (M+H) + = 269.1.

[0089] (7) Preparation of 2-chloro-7-(3-phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine 7-(3-Phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridin-2-ol (0.29 g) was weighed, phosphorus oxychloride (6 mL) was added, the temperature was raised to 100 °C and stirred for 10 hours, the solvent was removed under reduced pressure, ice water and dichloromethane were added, adjusted to pH = 9 - 10 with an aqueous Na2CO3 solution, separated and extracted, and the organic phase was concentrated until dry to obtain a crude product (0.6 g) of the title compound.

[0090]

Chem.

[0091] MS(ESI) m / z (M+H) + = 287.1.

[0092] (8) Preparation of tert-butyl 2-chloro-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate 2-Chloro-7-(4-methoxyphenethyl)-5,6,7,8-tetrahydro-1,6-naphthyridine (0.6 g) was weighed, dissolved in dichloromethane (5 mL) and water (5 mL), the sodium carbonate solution was added to adjust to pH = 8 - 9, and di-tert-butyl dicarbonate (0.50 mL) was added. Stirred at room temperature for 1 hour, concentrated under reduced pressure until dry, and purified by column chromatography to obtain the title compound (0.22 g).

[0093]

Chem.

[0094] MS(ESI) m / z (M+H) + = 387.1.

[0095] (9) Preparation of tert-butyl 2-(benzylthio)-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthylpyridine-6(5H)-carboxylate tert-Butyl 2-chloro-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthyridine-6-(5H)-carboxylate (147 mg), benzyl mercaptan (71 mg), tris(dibenzylideneacetone)dipalladium (35 mg), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (44 mg) and triethylamine (113 μL) were weighed into a reaction flask, 1,4-dioxane (5 mL) was added, the mixture was purged with nitrogen, and the reaction was carried out at 100 °C overnight. The mixture was concentrated to dryness under reduced pressure and purified by column chromatography to obtain the title compound (159 mg).

[0096]

Chemical Structure

[0097] MS(ESI) m / z (M+H) + = 475.2.

[0098] (10) Preparation of tert-butyl 2-(chlorosulfonyl)-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate tert-Butyl 2-(benzylthio)-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthylpyridine-6(5H)-carboxylate (156 mg) was weighed, dissolved in acetonitrile (5 mL), and acetic acid (79 mg), water (48 mg) and 1,3-dichloro-5,5-dimethylhydantoin (130 mg) were sequentially added under an ice bath. The mixture was stirred in the ice bath for 1 hour, ice water and dichloromethane were added, and liquid-liquid extraction was carried out. The organic phase was concentrated to dryness, and the crude product of the title compound (148 mg) was obtained.

[0099]

Chemical Structure

[0100] MS(ESI) m / z (M+H) + = 451.1.

[0101] (11) Preparation of Sodium 6-(tert-Butoxycarbonyl)-7-(3-phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-sulfonate tert-Butyl 2-(Chlorosulfonyl)-7-(3-phenylpropyl)-7,8-dihydro-1,6-naphthyridine-6(5H)-carboxylate (148 mg) was weighed and dissolved in tetrahydrofuran (5 mL) and water (5 mL). Sodium hydroxide (27 mg) was added, and the mixture was stirred at 80 °C for 1 hour. Ethyl acetate and water were added, and liquid-liquid extraction was performed. The organic phase was discarded, and the aqueous phase was concentrated until dry to obtain a crude product (50 mg) of the title compound.

[0102]

Chemical Structure

[0103] MS(ESI) m / z (M+H) + = 433.1.

[0104] (12) Preparation of 7-(3-Phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-sulfonic Acid Hydrochloride The crude product of sodium (tert-Butoxycarbonyl)-7-(3-phenylpropyl)-5,6,7,8-tetrahydro-1,6-naphthyridine-2-sulfonate (50 mg) was taken, dissolved in 6M hydrochloric acid solution (3 mL), stirred at room temperature for 1 hour, concentrated until dry, and separated by pre-HPLC to obtain the title compound (Test Compound 3, 2.25 mg).

[0105]

Chemical Structure

[0106] MS(ESI) m / z (M+H) + = 333.0.

[0107] 11H NMR (400 MHz, D2O) δ 7.74 (dd, J = 18.5, 8.1 Hz, 2H), 7.24 (ddd, J = 21.9, 14.9, 7.3 Hz, 5H), 4.42 (s, 2H), 3.72 - 3.62 (m, 1H), 3.32 - 3.22 (m, 1H), 3.01 - 2.92 (m, 1H), 2.63 (d, J = 3.6 Hz, 2H), 1.83 - 1.58 (m, 4H).

[0108] 4. Experimental Results Using the above experimental method, the pharmacological activity of the test compound of the present invention was verified. Through the statistical analysis of appearance, biochemical and pathological indicators, the results proved that the application of the test compound of the present invention can effectively reduce the pigmentation of rat skin and has an obvious improvement effect on the chloasma symptoms of model rats.

[0109] According to the experimental methods in Items 3.1 to 3.4, on the 58th day, that is, the end day of the experiment, the collected experimental data was analyzed. The specific results are shown in Figure 1.

[0110] 4.1 The following results were obtained by the classification evaluation of the appearance indicators in Figures 1A and 1E. No obvious changes were observed in the back skin of the control group rats; obvious dark brown skin damage areas were observed in the model group rats, and the skin damage area was large; compared with the model group, in the tranexamic acid group at 5 mg / mL and the test compound group rats, the skin damage areas all became significantly lighter in color, light brown, and the skin damage area was significantly reduced (P < 0.05).

[0111] 4.2 The following can be seen from the HE staining results in Figure 1B. The epidermal tissue structure of the control group rats was complete, the arrangement of stratum corneum cells was orderly, there was no obvious fiber proliferation, and no inflammatory cell infiltration was observed; compared with the control group rats, in the epidermal tissue of the model group rats, obvious increases in the thickness of the granular layer, spinous layer and stratum corneum of the skin tissue, disorder of the arrangement structure of the skin tissue, and uneven distribution phenomenon appeared, and inflammatory cell infiltration was observed; compared with the model group, in the tranexamic acid group at 5 mg / mL and the test compound group, the thickness of the basal layer and spinous layer of the epidermal tissue was significantly reduced, the arrangement of the skin tissue structure became gradually flat, and the phenomenon of inflammatory cell infiltration was improved.

[0112] 4.3 According to the results of Fontana-Masson staining in Figure 1C, the positive expression of melanin particles showed black, and the cell nuclei showed red; there were almost no black positive regions in the stained sections of the control group; the area of the black positive region in the epidermal sections of the model group was the largest, the color was the darkest, and it showed a continuous band-like distribution, with a significant increase in melanin particles, and a large number of continuously distributed band-like melanin particles appeared in the basal cells and spinous layers, and densely distributed melanin particles and melanin caps appeared in the epidermal layer; grade evaluation was performed on the content of melanin particles in the rat skin tissue in Figure 1F. Compared with the model group, the 5mg / mL tranexamic acid group had a reduced area of the black positive region in the section, a lighter color, a decrease in melanin particles in the skin tissue, and the distribution of melanin particles was band-like, but mainly concentrated in the basal layer and spinous layer; compared with the model group, the 5mg / mL test compounds 1 and 3 groups had a significantly reduced area of the black positive region in the section, a significantly lighter color, a significantly reduced number of melanin particles in the skin tissue, and discontinuously distributed melanin particles were only seen in the basal layer.

[0113] 4.4 According to the color development results of immunohistochemical tyrosinase in Figures 1D and 1G, the positive expression of tyrosinase showed yellowish-brown, and the cell nuclei showed blue; there were almost no yellowish-brown regions in the immunohistochemical sections of the control group, indicating low expression of tyrosinase in the rat skin tissue; the area of the tyrosinase positive region in the rat skin tissue sections of the model group was the largest, and the yellowish-brown color was obvious, indicating a high positive rate of tyrosinase in the rat skin tissue of the model group; compared with the model group, the 5mg / mL tranexamic acid, test compound 1 group and test compound 3 group had a significantly reduced area of the tyrosinase positive expression region in the skin tissue section, a significantly lighter color, and a significantly reduced positive rate of tyrosinase in the skin tissue (P<0.001); compared with the model group, the 1.5 and 5mg / mL test compound 2 showed significant differences (P<0.01).

[0114] 4.5 The skin tissue homogenate of Figure 1H was used to measure the content of ET-1 by ELISA method. The content of ET-1 in the skin tissue of the model group rats was significantly increased compared with the control group. The tranexamic acid and test compound groups at 5 mg / mL were significantly decreased compared with the model group, and there was a significant difference (P<0.01).

[0115] 4.6 Figure 1I shows that there was no significant difference in the body weight among the rats in each group during the whole experimental process, indicating that the animals had good tolerance to the test substances.

[0116] As above, the embodiments of the technical solution of the present invention have been exemplarily described. It should be understood that the scope of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the scope of the spirit and principles of the present invention should be included within the protection scope of the claims of this application.

Brief Description of the Drawings

[0117]

Figure 1

Claims

1. Use of a compound represented by formula I, a pharmaceutically acceptable salt, hydrate, isomer, prodrug, or a mixture thereof, for manufacturing a product for improving pigmentation. 【Chemical 1】 However, R １ is selected from a carboxyl group, a phosphate group, and a sulfonic acid group; R ２ is hydrogen, a substituted or unsubstituted amino group, a substituted or unsubstituted C １ - C ６ alkyl group, a substituted or unsubstituted C １ - C ６ alkoxy group, a C １ - C ４ haloalkyl group, a substituted or unsubstituted C ３ - C ６ cycloalkyl group, a substituted or unsubstituted 4 - 8 membered aliphatic heterocyclic group, a substituted or unsubstituted 6 - 10 membered aryl group, a substituted or unsubstituted 6 - 10 membered aromatic heterocyclic group.

2. R ２ is hydrogen, an unsubstituted or optionally substituted by one or two or more R ２ａ amino group, a C １ - C ６ alkyl group, a C １ - C ６ alkoxy group, a C １ - C ４ haloalkyl group, a C ３ - C ６ cycloalkyl group, a 4 - 8 membered aliphatic heterocyclic group, a 6 - 10 membered aryl group, a 6 - 10 membered aromatic heterocyclic group, selected from, said R ２ａ is halogen, OH, NH ２ NO ２ CN, oxo (=O), C １ - C ６ alkyl group, a C １ - C ６ alkoxy group, a C ３ - C ６The use according to claim 1, characterized in that it is selected from a cycloalkyl group, a 4- to 8-membered aliphatic heterocyclic group, a 6- to 10-membered aryl group, and a 6- to 10-membered aromatic heterocyclic group.

3. Said R ２ is hydrogen, a phenyl group which is unsubstituted or optionally substituted with one or two or more R ２ａ and is selected from phenyl-C １ -C ６ alkyl-. The use according to claim 1 or 2, characterized in that it is selected from the group consisting of

4. Said R ２ is hydrogen, 【Chemical Formula 2】 The use according to any one of claims 1 to 3, characterized in that it is selected from the group consisting of

5. The pigmentation may be a disease related to pigmentation, and the disease related to pigmentation refers to a disease caused by the deposition of melanin on the surface layer of the skin. The use according to any one of claims 1 to 4, characterized in that it is selected from the group consisting of

6. The use according to claim 5, characterized in that the disease related to pigmentation includes one or more of chloasma, senile lentigo, freckles, melasma, facial macules, and nevus flammeus.

7. The use according to claim 5, characterized in that the disease related to pigmentation is chloasma.

8. The compound of formula I is selected from a compound having the following chemical structure, its pharmaceutically acceptable salt, hydrate, isomer, prodrug or mixture. The use according to any one of claims 1 to 7, characterized in that it is selected from the group consisting of 【Chemical Formula 3】

9. The pharmaceutically acceptable salt is the hydrochloride salt of the compound of formula I. The use according to any one of claims 1 to 8, characterized in that it is selected from the group consisting of

10. The use according to any one of claims 1 to 9, characterized in that the product for improving the pigmentation may be a pharmaceutical or a cosmetic.

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