Preparation method and application of indole alkaloid derivative

Abstract

The invention discloses a synthesis method and application of an indole alkaloid derivative. According to the method, 5-aminoindole or 6-aminoindole which is simple and easy to prepare is used as a substrate, the substrate reacts with acyl chloride or carboxylic acid to obtain an intermediate, and then the intermediate reacts with Hydroxyclavatol to obtain the Pendolone (PND) derivative disclosed by the invention. The method has the advantages of easily available raw materials, short reaction time, few involved steps, simple post-treatment and the like; the indole alkaloid PND derivative prepared by the invention has good anti-influenza virus activity and a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical chemical synthesis and relates to the structure and synthesis method of an indole alkaloid derivative. Background Art

[0002] Amide bonds often appear in many natural products and drug molecules and are important functional groups of biomolecules and drugs, which have unique physical properties and application values in compounds. A novel indole alkaloid compound Penindolone (PND) has the activity of inhibiting influenza A virus. In order to improve the anti-influenza virus activity and drug-likeness of PND derivatives, the present invention introduces an amide bond as a linking bond between the indole benzene ring and substituents of PND, and these results provide a certain reference for the development of this indole alkaloid compound.

[0003] Summary of the Invention

[0004] The first object of the present invention is to provide a novel PND derivative containing an amide bond that has a good inhibitory effect against influenza virus.

[0005] The second object of the present invention is to provide a simple synthesis method for preparing the PND derivative that achieves the first object.

[0006] The technical solution for achieving the first object of the invention is that in the structure of the PND derivative, the 5-position or 6-position of the indole is connected to a 3,4,5-trimethoxyphenyl substituent through an amide bond, and its Structures I and II are respectively:

[0007] Or it is formed by connecting the 5-position or 6-position of the indole in PND to (4-methyl-piperazinyl)ethyl through an amide bond, and its Structures III and IV are respectively:

[0008] The technical solution for achieving the second object of the invention is a preparation method of an indole alkaloid derivative, and the PND derivative that achieves the first object of the invention is prepared by this method; the method has the following preparation steps: React 5-nitroindole or 6-nitroindole with hydrogen to obtain indole with amino substitution at the 5-position and 6-position of the indole; weigh 5-aminoindole or 6-aminoindole in a round-bottom flask, add a solvent to completely dissolve it, and then slowly add differently substituted acyl chlorides or differently substituted carboxylic acids and continue to react at room temperature. After the reaction is complete, quench it, and purify it by column chromatography to obtain an intermediate product, which is further used as one of the reactants to react with Hydroxyclavatol ( Figure 1 ) to generate a PND derivative.

[0009] As a preferred technical solution, the specific synthesis route of the above synthesis method is as follows:

[0010] As a preferred technical solution, the chemical general formula of different substituted acyl chlorides is RCOCl, and the chemical general formula of different substituted carboxylic acids is RCOOH. The above R structure is selected from any one of substituted or unsubstituted C 1-5 alkyl groups, C 3-7 cycloalkyl groups, benzyl groups, and aryl groups, where the substituent groups include halogens.

[0011] As a preferred technical solution, the solvents include methanol, dichloromethane, N,N-dimethylformamide, and toluene.

[0012] As a preferred technical solution, the quenching agent for quenching is water or saturated brine.

[0013] As a preferred technical solution, the molar ratio of different substituted acyl chlorides or different substituted carboxylic acids to amino-substituted indoles is 1.5:1.

[0014] As a preferred technical solution, the molar ratio of the intermediate product obtained by the reaction of different substituted acyl chlorides or different substituted carboxylic acids with amino-substituted indoles to Hydroxyclavatol is 1:2.

[0015] Then, the anti-PR8 (H1N1) influenza virus activity was detected by the cytopathic effect inhibition experiment. Using the antiviral drug oseltamivir as the positive drug, the prepared PND derivatives I-IV were compared and verified with PND. The verification results are shown in the following table: Table 1 Anti-influenza virus test results Compound <![CDATA[IC 50 (μM)]]> <![CDATA[CC 50 (μM)]]> SI Ⅰ 2.4 ± 0.3 ＞1200 ＞500.0 Ⅱ 3.3 ± 0.5 ＞1200 ＞363.6 Ⅲ 3.7 ± 0.7 ＞1200 ＞324.4 Ⅳ 2.5 ± 1.0 ＞1200 ＞387.2 PND 26.1 ±1.3 ＞300 ＞11.5 Oseltamivir 11.4 ± 2.7 ＞300 ＞26.3 As can be seen from Table 1, the four PND derivatives (structural formulas I-IV) prepared by the preparation method provided by the present invention all have good anti-influenza virus activity, which is better than PND and the positive drug oseltamivir, and at the same time has good safety ( Figure 2 )

[0016] The present invention uses 5 - aminoindole or 6 - aminoindole, which is simple and easy to prepare, as a substrate, reacts with different substituted acyl chlorides or different substituted carboxylic acids at room temperature. After the reaction is complete, it is quenched and purified by column chromatography to obtain an intermediate product, which is further used as one of the reactants to react with Hydroxyclavatol to generate PND derivatives. Therefore, the present invention provides a method for synthesizing indole alkaloid PND derivatives. This method has easily available raw materials, a short reaction time, and simple post - treatment, and has broad application prospects. In addition, the indole alkaloid PND derivatives prepared by the preparation method provided by the present invention have good anti - influenza virus activity and have great application value in the preparation of anti - influenza virus drugs. Specific embodiments: The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. However, it should be understood that these embodiments are only used to illustrate the present invention to help understand the disclosed content of the present invention, rather than limiting the scope of the present invention, and the protection scope of the present invention is not limited to the following embodiments.

[0018] The present invention has no special restrictions on the sources of the raw materials in the following embodiments, and they can be prepared by the preparation methods well - known to those skilled in the art or purchased commercially.

[0019] In the embodiments of the present invention, the nuclear magnetic resonance spectra ( 1 H NMR, 13 C NMR) of the compounds were measured by Bruker AVANCE 400 and JEOLJN M - ECP 600, and the solvent was deuterated dimethyl sulfoxide. The chemical shifts δ are cited in ppm units, using tetramethylsilane as an internal standard, and the multiplicities are as follows: s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet. High - resolution mass spectrometry (HRMS) was measured by Thermo Scientific LTQ Orbitrap XL.

[0020] Example 1: Synthesis method of indole alkaloid PND derivatives (compounds shown in Formulas I and II): In a 50 mL round-bottom flask, add 5-nitroindole or 6-nitroindole (5.0 mmol) dissolved in 15 mL of methanol, then add 10% (mass fraction) palladium on carbon, and then stir and react at 40 °C for 2 h under a hydrogen atmosphere. Monitor the reaction by TLC until the reaction is complete. Filter off the residual palladium on carbon with diatomaceous earth, then concentrate under reduced pressure, and purify the sample by silica gel column chromatography (petroleum ether:ethyl acetate = 1:1) to obtain 5-aminoindole and 6-aminoindole. Dissolve 5-aminoindole or 6-aminoindole (0.68 mmol) in dichloromethane (DCM, 6 mL), and then slowly add 3,4,5-trimethoxybenzoyl chloride (1.02 mmol) and triethylamine (TEA, 1.36 mmol). Stir at room temperature for 0.5 h and monitor the reaction by TLC until the reaction is complete. Extract the reaction solution with DCM twice, combine the organic phases, wash with saturated brine three times, and use anhydrous Na 2 SO 4 Dry the organic layer, concentrate the organic phase under reduced pressure, and purify the sample by silica gel column chromatography (petroleum ether:ethyl acetate = 20:1 to 1:1) to obtain the intermediate product. Carry out a one-step Michael addition reaction of the intermediate product (0.5 mmol) with Hydroxyclavatol (1.0 mmol) in a toluene solution and stir at 110 °C for 3 - 6 h. After the reaction is completed, if a solid precipitates, directly filter to obtain the product. If no solid precipitates, concentrate the solution under reduced pressure and recrystallize with ethyl acetate and petroleum ether. Purify the product with a purity still lower than 95% by silica gel column chromatography.

[0021] The structure of the compound shown in Formula I is:

[0022] N-(2,3-bis(3-acetyl-2,6-dihydroxy-5-methylbenzyl)-1H-indol-5-yl)-3,4, 5-trimethoxybenzamide. Yellow solid, yield: 28.7%, melting point: 200−201 °C. 1 H NMR (400 MHz, DMSO- d 6 ): δ 13.08 (s, 1H), 13.05 (s, 1H), 9.84 (s, 1H), 9.75 (s, 1H), 9.66 (s,1H), 9.44 (s, 1H), 7.74 (s, 1H), 7.63 (s, 1H), 7.53 (s, 1H), 7.28 (s, 2H),7.17 (d, J = 8.6 Hz, 1H), 7.05 (dd, J= 8.6, 2.0 Hz, 1H), 4.22 (s, 2H), 4.09 (s, 2H), 3.86 (s, 6H), 3.73 (s, 3H), 2.56 (s, 3H), 2.51 (s, 3H), 2.19 (s, 3H), 2.16 (s, 3H); 13 C NMR (100 MHz, DMSO- d 6 ): δ 203.67, 203.59, 164.71, 161.25, 161.17, 161.17, 161.12, 153.00, 152.99, 152.99, 140.28, 135.87, 132.99, 131.90, 131.20, 131.06, 129.84, 128.38, 116.44, 116.20, 115.42, 113.37, 113.10, 113.03, 112.83, 110.65, 109.16, 105.50, 105.50, 60.56, 56.47, 56.47, 26.69, 26.69, 20.23, 18.20, 16.92, 16.87. HRMS: calcd for C 38 H 39 N 2 O 10 [M + H] + , 683.2599; found, 683.2579. The structure of the compound shown in Formula II is:

[0023] N-(2,3-bis(3-acetyl-2,6-dihydroxy-5-methylbenzyl)-1H-indol-6-yl)-3,4, 5-trimethoxybenzamide. White solid, yield 35.7%, melting point: 188−190 °C. 1 H NMR (400 MHz, DMSO- d 6 ): δ 13.09 (s, 1H), 13.04 (s, 1H), 9.87 (s, 2H), 9.64 (s, 1H), 9.52 (s, 1H), 7.76 (s, 1H), 7.62 (s, 1H), 7.55 (s, 1H), 7.35 (d, J = 8.3 Hz, 1H), 7.22 (s, 2H), 6.95 (d, J= 8.6 Hz, 1H), 4.24 (s, 2H), 4.09 (s, 2H), 3.84 (s, 6H), 3.71 (s, 4H), 2.55 (s, 3H), 2.53 (s, 3H), 2.19 (s, 3H), 2.17 (s, 3H); 13 C NMR(100 MHz, DMSO- d 6 ): δ 203.76, 203.63, 164.85, 161.23, 161.20, 161.19, 161.08, 153.00, 153.00, 153.00, 140.37, 135.44, 135.21, 132.10, 131.81, 131.23, 131.18, 125.46, 118.28, 116.45, 116.27, 115.58, 113.54, 113.31, 113.03, 112.82, 108.95, 105.58, 104.27, 60.55, 56.50, 56.50, 26.67, 26.67, 20.25, 18.29, 16.90, 16.89. HRMS: calcd for C 38 H 39 N 2 O 10 [M + H] + , 683.2599; found, 683.2584. Example

[0024] Synthetic method of indole alkaloid PND derivatives (compounds shown in formulas III and IV): Dissolve 5-aminoindole or 6-aminoindole (0.68 mmol) in dichloromethane (DCM, 6 mL), then slowly add 4-methyl-1-piperazineacetic acid (1.02 mmol), then add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 0.82 mmol) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (HOBt, 0.82 mmol), stir at room temperature for 3 - 6 h, monitor by TLC until the raw materials no longer change. Quench the reaction with water and extract twice with DCM. Combine the organic phases and use anhydrous Na 2 SO 4Dry and concentrate under reduced pressure. Separate it by silica gel column using eluent (methylene chloride:methanol = 40:1 to 10:1) to obtain the intermediate. Carry out a one-step Michael addition reaction of the intermediate product (0.5 mmol) and Hydroxyclavatol (1.0 mmol) in toluene solution, and stir at 110 °C for 3 - 6 h. After the reaction is completed, if a solid precipitates, directly filter to obtain the product. If no solid precipitates, concentrate the solution under reduced pressure and recrystallize with ethyl acetate and petroleum ether. Purify the product with a purity still lower than 95% by silica gel column chromatography.

[0025] The structure of the compound shown in Formula III is:

[0026] N-(2,3-bis(3-acetyl-2,6-dihydroxy-5-methylbenzyl)-1H-indol-5-yl)-2- (4-methylpiperazin-1-yl)acetamide. White solid, yield: 35.8%, melting point: 171−173 °C. 1 HNMR (400 MHz, DMSO- d 6 ): δ 13.09 (s, 1H), 13.03 (s, 1H), 9.73 (s, 1H), 9.68 (s,1H), 9.60 (s, 1H), 9.44 (s, 1H), 7.69 (d, J = 1.9 Hz, 1H), 7.62 (s, 1H), 7.53(s, 1H), 7.12 (d, J = 8.6 Hz, 1H), 7.04 (dd, J = 8.6, 2.0 Hz, 1H), 4.21 (s, 2H),4.06 (s, 2H), 3.46 (s, 2H), 3.24 (s, 8H), 2.83 (s, 3H), 2.55 (s, 3H), 2.53(s, 4H), 2.19 (s, 3H), 2.15 (s, 3H); 13 C NMR (100 MHz, DMSO- d 6 ): δ203.69, 203.62, 161.32, 161.26, 161.22, 161.15, 160.97, 136.06, 132.80, 131.90, 131.26, 129.49, 128.37, 116.44, 116.20, 115.47, 114.56, 113.91, 113.37, 113.01, 112.82, 110.77, 109.14, 52.39, 52.36, 51.96, 49.74, 49.66, 40.90, 26.74, 26.70, 20.21, 18.12, 16.87, 16.87. HRMS: calcd for C 35 H 41 N 4 O 7 [M + H] + , 629.2970; found, 629.2982. The structure of the compound shown in Formula IV is:

[0027] N-(2,3-bis(3-acetyl-2,6-dihydroxy-5-methylbenzyl)-1H-indol-5-yl)-2- (4-methylpiperazin-1-yl)acetamide. Pale yellow solid, yield 27.7%, melting point: 165−167 °C. 1 HNMR (400 MHz, DMSO- d 6 ): δ 13.09 (s, 1H), 13.04 (s, 1H), 10.03 (s, 1H), 9.87 (s, 1H), 9.67 (d, J = 72.5 Hz, 2H), 7.70 (d, J = 2.0 Hz, 1H), 7.61 (s, 1H), 7.54 (s, 1H), 7.35 (d, J = 8.4 Hz, 1H), 6.86 (d, J = 8.4 Hz, 1H), 4.24 (s, 2H), 4.08 (s, 2H), 3.83 (s, 2H), 3.65 – 3.17 (m, 8H), 2.85 (s, 3H), 2.55 (s, 3H), 2.53 (s, 3H), 2.20 (s, 3H), 2.17 (s, 3H); 13 C NMR (100 MHz, DMSO- d 6 ):δ 203.75, 203.62, 164.14, 161.24, 161.17, 161.13, 161.09, 135.40, 131.81, 131.24, 125.50, 118.57, 117.84, 116.48, 116.28, 115.55, 114.94, 113.51, 113.00, 112.79, 111.83, 108.99, 102.90, 58.39, 51.10, 49.33, 49.33, 49.04, 42.52, 26.66, 26.66, 20.20, 18.23, 16.86, 16.86. HRMS: calcd for C 35 H 41 N 4 O 7 [M + H] + , 629.2970; found, 629.2980. Experimental Example 1: Antiviral Activity Assay Test method: First, infect MDCK cells with H1N1 / PR8 (MOI = 0.1). After removing the virus inoculum, treat the cells with different concentrations of the compound, with 3 replicate wells in each group. After culturing for 48 h, when obvious cytopathic effects appeared in the virus control group, fix the cells with 4% paraformaldehyde at room temperature for 20 min. Then remove the paraformaldehyde and stain with 0.1% crystal violet for another 30 minutes. Then wash and dry, and measure the absorbance of each well at 570 nm. In addition, the cytotoxicity experiment of the PND derivative on MDCK cells was detected by the thiazolyl blue colorimetric method (MTT). Cell survival rate (%) = (OD value of the experimental group - OD value of the blank control group) / (OD value of the negative control group - OD value of the blank control group) × 100%. The above experiments were repeated 3 times.

[0028] Perform the above tests on the indole alkaloid PND derivatives prepared in Examples 1 - 2, and the results are shown in Table 1 and Figure 2 as follows.

[0029] The conventional techniques in the above examples are the existing techniques known to those skilled in the art, so they will not be described in detail here.

[0030] As described above, the above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. Brief Description of the Drawings

[0031] Figure 1 : Chemical synthesis method of the compound Hydroxyclavatol.

[0032] Figure 2 : Cytotoxic effects of the compounds shown in Formulas I, II, III and IV on MDCK cells.

Claims

1. A compound of formula A or formula B or a pharmaceutically acceptable salt thereof, wherein the R structure is selected from any substituted or unsubstituted C 1-5 Alkyl, C 3-7 One of cycloalkyl, benzyl, aryl, wherein the substituent group includes halogen, 。 2. A chemical synthesis method of the compound of claim 1, comprising reacting the compound Hydroxyclavatol with a compound of formula C or a compound of formula D in an organic solvent, preferably at 110°C for 3-6 h, to obtain compounds of formula A and formula B of claim 1, wherein the structure of R is as defined in claim 1; the organic solvent is preferably selected from aprotic solvents such as toluene, dioxane, DMSO and tetrahydrofuran, more preferably toluene, 。 3. Use of the compound according to claim 1 in the preparation of antiviral drugs.

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