Spirooxindole alkaloid in indigo plant as well as preparation method and application of spirooxindole alkaloid

Abstract

The invention belongs to the technical field of medicines, and relates to four spirooxindole alkaloids extracted and separated from persicaria tinctoria as well as a preparation method and application of the four spirooxindole alkaloids. Compounds 1a / 1b are a pair of enantiomers having a 6 / 5 / 5 / 6 tetracyclic system and a 3-phenyl-4, 5-dihydro-3H-spiro [furan-2, 3 '-indoline] skeleton. The compound 2 and the compound 3 have a 6 / 5 / 6 / 5 / 6 pentacyclic system skeleton and a 3 '-methyl-2', 3 ', 4', 9 '-tetrahydrospiro [indole-3, 1'-pyrido [3, 4-b] indole] skeleton. The invention also relates to a separation and biomimetic synthesis preparation method of the compound, and application of the compound in preparation of drugs for treating neurodegenerative diseases. Reagents needed by the preparation method are low in price and convenient and easy to obtain, and the obtained compound has a good neuroprotective effect, has the advantages of being easy and convenient to operate and good in reproducibility, is beneficial to industrial production and has high potential value and wide application prospects in the fields of medicine and medicinal chemistry and synthesis of natural products. # imgabs0 #

Description

Technical field:

[0001] The invention belongs to the field of medical technology, and particularly relates to new spiro-oxindole alkaloids in the plant Polygonum indigofera, separation and biomimetic synthesis preparation methods thereof, and application of such compounds in protecting nerve cells. Background technology:

[0002] Persicariatinctoria (Aiton) Spach, belonging to the Polygonaceae family, is an annual herb that is cultivated or semi-wild in various parts of the country. The leaves of Polygonum tinctoria have a long history of use in my country, and the dried leaves are used as Polygonum tinctoria. It is cold in nature, bitter in taste, and has the effects of clearing away heat and detoxifying, cooling blood and removing spots.

[0003] According to the latest statistics from the World Health Organization, the number of people at high risk of neurodegenerative diseases has climbed to 200 million worldwide, and the number of newly confirmed cases has increased dramatically each year, ranging from 1 million to 2 million. Therefore, it is necessary to develop therapeutic drugs for neurodegenerative diseases. Oxidative stress is closely related to many neurodegenerative diseases, and oxidative stress caused by glutamate (Glu) is an important cause of neurodegenerative diseases. Summary of the invention:

[0004] The purpose of the present invention is to provide new spiro-oxindole alkaloids from the plant Polygonum indigofera and separation and biomimetic synthesis preparation methods thereof and application of such compounds in protecting nerve cells.

[0005] The present invention relates to a new spirooxindole alkaloid isolated from Persicaria tinctoria, a plant of the Polygonum genus of the Polygonaceae family, and its structure is shown in the figure:

[0006]

[0007] The technical solution for separating and preparing the new spirooxindole alkaloids in Polygonum indigofera of the present invention comprises the following steps:

[0008] The dried leaves of Polygonum indigofera were extracted with ethanol, and the extracts were combined and concentrated to obtain an extract. The extract was extracted with dichloromethane and the resulting components were chromatographed on a silica gel column. The components were eluted with an isocratic gradient of dichloromethane-methanol system at a ratio of 100:1-1:1, and a total of 4 fractions AD were collected.

[0009] The fractions A and B were eluted with an ethanol-water system of 30:70-90:10 by gradient elution using an HP20 column chromatography to obtain two components A1 and A2; B1 and B2 respectively.

[0010] The A1 and B2 components were eluted by ODS column chromatography with an ethanol-water system of 30:70-90:10 for gradient elution to obtain three components A1-1-A1-3 and B2-1-B2-3 respectively.

[0011] The obtained components A1-3 were subjected to silica gel column chromatography with a dichloromethane-methanol system of 100:1-30:1 to obtain four subcomponents a1-a4 based on TLC analysis. The obtained components B2-3 were subjected to silica gel column chromatography with a dichloromethane-methanol system of 50:1-20:1 to obtain four subcomponents b1-b4 based on TLC analysis.

[0012] Compound a4 was separated by using methanol-water mobile phase on preparative reverse phase HPLC to obtain compound 1. Compound b4 was separated by using methanol-water mobile phase on preparative reverse phase HPLC to obtain compounds 2 and 3.

[0013] Compound 1 was separated on a Chiralpak AD-H chiral column using n-hexane-isopropanol as the mobile phase to obtain (+)-1 and (-)-1.

[0014] In the step, the indigo plant used is the dried leaves of Persicaria tinctoria, a plant of the genus Polygonum of the Polygonaceae family.

[0015] In the step, the dried leaves of Polygonum tinctorium are extracted with 70-80% industrial ethanol under reflux for 3-4 times, each time for 2-3 hours.

[0016] In the steps, a4 is separated on a preparative reverse phase high performance liquid chromatography using a 50:50 methanol-water mobile phase; and b4 is separated using a 60:40 methanol-water mobile phase.

[0017] In the step, compound 1 is separated on a Chiralpak AD-H chiral chromatographic column using a 5:1 n-hexane-isopropanol mobile phase.

[0018] The obtained compounds were systematically identified and the results are as follows:

[0019] The structures of compounds 1-3 were identified by high-resolution mass spectrometry, one-dimensional NMR, two-dimensional NMR, calculated ECD and X-ray single crystal diffraction. The corresponding spectra are shown in Figure 1-5 shown.

[0020] Compound 1: Pale yellow needle-shaped crystals. (+)-(1): (-)-(1): HRESIMS m / z 296.0914 [M+Na] + (calcd for C 17 H 14 NO 4,calcd for296.0917), the molecular formula is determined to be C 17 H 13 NO 4 , by analyzing its 1 H NMR, 13 C NMR, HMQC spectrum, HMBC spectrum, and X-ray single crystal diffraction confirmed the structure of compound 1, which is a new compound. After chiral separation and ECD calculation, the absolute configuration was determined to be (+)-(3S,7'R)-1 and (-)-(3R,7'S)-1.

[0021] Compound 2: yellow solid. HRESIMS m / z348.1345[M+H] + (calcdfor C 20 H 18 N 3 O 3 ,348.1343). The molecular formula is determined to be C 20 H 17 N 3 O 3 , by analyzing its 1 HNMR, 13 C NMR, HMQC, HMBC and calculated ECD confirmed the structure of compound 2, which is a new compound, and its absolute configuration is determined to be 3S, 9′R.

[0022] Compound 3: yellow solid. HRESIMS m / z348.1351[M+H] + (calcdfor C 20 H 18 N 3 O 3 ,348.1343). The molecular formula is determined to be C 20 H 17 N 3 O 3 , by analyzing its 1 HNMR, 13 C NMR, HMQC, HMBC and calculated ECD confirmed the structure of compound 2, which is a new compound, and its absolute configuration is 3R,9′R.

[0023] Table 1: Compounds 1-3 1 H(600MHz) and 13 C (150MHz) data (DMSO-d 6 )

[0024]

[0025]

[0026] The biomimetic synthesis preparation method of the new spiro-oxindole alkaloid compound 1 in Polygonum indigofera of the present invention comprises the following steps:

[0027]

[0028] 3-Hydroxyindolinone and trans-p-coumaric acid methyl ester, a solvent and a catalyst are added to a sealed tube equipped with a magnetic pole, and an inert gas is introduced after sealing. The reaction is stirred at reflux temperature for 16-24 hours, and the solvent is removed under reduced pressure to obtain a crude product; the crude product is purified by column chromatography to obtain spirohydroxyindole alkaloid compounds (±)-1 and 7′-epi-(±)-1; and then chiral separation is performed to obtain enantiomers (+)-1 and (-)-1, 7′-epi-(+)-1 and 7′-epi-(-)-1, respectively.

[0029] In the steps, the solvent is p-xylene, and the catalysts are ruthenium dodecacarbonyl, DPPP and potassium tert-butoxide.

[0030] In the step, the crude product is separated by column chromatography using petroleum ether-ethyl acetate in a ratio of 3:1-2:1.

[0031] The biomimetic synthesis preparation method of the new spiro-oxindole alkaloid compound 2 and compound 3 in Polygonum indigofera of the present invention comprises the following steps:

[0032]

[0033] D-tryptophan methyl ester hydrochloride and isatin were added to a sealed tube equipped with a magnetic pole, dissolved in anhydrous methanol, TFA was added, stirred for 10 minutes, and then moved to 90°C for reaction. The solvent was removed under reduced pressure to obtain a crude product; the crude product was purified by column chromatography to obtain spiro-hydroxyindole alkaloid compounds 2 and 3.

[0034] In the steps, the reflux time is 0.5-1h.

[0035] In the step, the crude product is separated by column chromatography using dichloromethane-methanol in a ratio of 100:0-80:1.

[0036] The present invention also provides a pharmaceutical composition, which comprises the above-mentioned new spirooxindole alkaloid or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable carrier or excipient.

[0037] The pharmaceutical composition is in a clinically acceptable dosage form.

[0038] Preferably, the dosage form is an injection, a tablet or a capsule.

[0039] The present invention also provides a Polygonum indigofera extract, comprising the above-mentioned new spiro-oxindole alkaloid.

[0040] The present invention also provides the use of the novel spiro-oxindole alkaloid or a pharmaceutical composition containing the novel spiro-oxindole alkaloid in the preparation of a neuron protective drug.

[0041] The present invention also provides the use of the novel spiro-oxindole alkaloid or a pharmaceutical composition containing the novel spiro-oxindole alkaloid in the preparation of a drug for preventing and / or treating neurodegenerative diseases.

[0042] The neuroprotective activity of the new spiro-oxindole alkaloids of the invention was investigated. The Glu injury model is a commonly used model for studying neuronal cell death caused by oxidative stress. In the glutamate Glu-induced neurotoxicity cell model of the mouse hippocampal neuron cell line HT22, compounds 1-3 showed obvious in vitro neuroprotective effects. Therefore, the new spiro-oxindole alkaloids of the invention have the prospect of further developing drugs for the prevention and treatment of neurodegenerative diseases.

[0043] The advantages of the present invention are that the compounds are all new compounds with novel structures and strong neuron-protecting activity, and are worth further development. Description of the drawings:

[0044] Figure 1 HRESIMS of compound 1, 1 H. 13 C-NMR, DEPT and HMBC spectra;

[0045] Figure 2 HRESIMS of compound 2, 1 H. 13 C-NMR, DEPT and HMBC spectra;

[0046] Figure 3 HRESIMS of compound 3, 1 H. 13 C-NMR, DEPT and HMBC spectra;

[0047] Figure 4 ECD diagrams of compounds 1-3;

[0048] Figure 5 X-ray single crystal data of compounds 1 and 3. Specific implementation method:

[0049] The following examples are provided to help those skilled in the art better understand the present invention, but are not intended to limit the present invention in any way. Anhydrous toluene was prepared by adding sodium strips and refluxing and distilling in the presence of nitrogen. Anhydrous methanol was obtained by purchasing a diaphragm bottle equipped with a molecular sieve. The chemical reactions involved were all analyzed by TLC using GF-254 thin-layer silica gel plates. The extraction and separation of the reaction solution were all achieved by column chromatography using 200-300 mesh silica gel as a filler. 1 H NMR and 13 CNMR was measured using Bruker Avance-III 600 with deuterated dimethyl sulfoxide as solvent.

[0050] Embodiment 1:

[0051] The isolation of new spiro-oxindole alkaloids is carried out as follows:

[0052] The dried leaves of Polygonum indigofera were extracted with ethanol, and the extracts were combined and concentrated to obtain an extract. The extract was extracted with dichloromethane and the resulting components were chromatographed on a silica gel column. The components were eluted with an isocratic gradient of dichloromethane-methanol system at a ratio of 100:1-1:1, and a total of 4 fractions AD were collected.

[0053] The fractions A and B were eluted with an ethanol-water system of 30:70-90:10 by gradient elution using an HP20 column chromatography to obtain two components A1 and A2; B1 and B2 respectively.

[0054] The A1 and B2 components were eluted by ODS column chromatography with an ethanol-water system of 30:70-90:10 for gradient elution to obtain three components A1-1-A1-3 and B2-1-B2-3 respectively.

[0055] The obtained components A1-3 were subjected to silica gel column chromatography with a dichloromethane-methanol system of 100:1-30:1 to obtain four subcomponents a1-a4 based on TLC analysis. The obtained components B2-3 were subjected to silica gel column chromatography with a dichloromethane-methanol system of 50:1-20:1 to obtain four subcomponents b1-b4 based on TLC analysis.

[0056] Compound a4 was separated on preparative reversed-phase HPLC using a mobile phase of methanol-water (50:50, v / v) to give compound 1. Compounds 2 and 3 were separated on preparative reversed-phase HPLC using a mobile phase of methanol-water (60:40, v / v).

[0057] Compound 1 was separated on a Chiralpak AD-H chiral chromatographic column using n-hexane-isopropanol mobile phase (5:1, v / v) to obtain 1a and 1b.

[0058] Embodiment 2:

[0059] The synthesis and preparation of the new spiro-oxindole alkaloid compound 1 is as follows:

[0060] 3-Hydroxyindolin-2-one (45 mg, 0.3 mmol), trans-p-coumaric acid methyl ester (107 mg, 0.6 mmol), triruthenium dodecacarbonyl (Ru) were added to a dry sealed pressure tube equipped with a magnetic stirrer. 3 (CO) 12 (3.8 mg, 0.006 mmol), 1,3-bis(diphenylphosphine)propane DPPP (4.2 mg, 0.018 mmol), potassium tert-butoxide t-BuOK (3.3 mg, 0.03 mmol) and toluene (15 mL). The tube was sealed with a rubber stopper and protected with nitrogen. Subsequently, the rubber stopper was quickly replaced with a threaded stopper under nitrogen purge. The mixture was heated at 140 ° C (oil bath temperature) for 20 hours. After the reaction was completed by TLC monitoring, the reaction solution was concentrated and column chromatography (SiO 2 ; petroleum ether:ethyl acetate = 3:1-2:1) to obtain a crude product as a light yellow solid (38.4 mg, 0.13 mmol, 42%). 1 H NMR spectrum determination (dr = 3:1). The crude product was separated on preparative HPLC (acetonitrile: water = 30:70, v / v, 2.5 mL / min, 210 nm) to obtain compound 1 (yield 10%) and its diastereomer 7′-epi-(±)-1 (yield 30%). Compound 1 was separated on a Chiralpak AD-H chiral chromatographic column using n-hexane-isopropanol mobile phase (5:1, v / v), and the enantiomeric ratio was 1:1.

[0061]

[0062] Compound (±)-1:TLC(SiO 2 ):R f =0.42 (petroleum ether:ethyl acetate=1:1).

[0063] 1 H NMR (600 MHz, DMSO-d 6)δ10.29(s,1H),9.41(s,1H),7.69(dd,J=7.6,1.2Hz,1H),7.33(td,J=7.6,1.2Hz,1H),7.13(td,J=7.6,1.0Hz,1H),6.73(d,J=8.6Hz,2H ), 6.72 (overlap, 1H), 6.55 (d, J = 8.6Hz, 2H), 4.24 (dd, J = 13.4, 8.2Hz, 1H), 3.49 (dd, J = 16.9, 13.4Hz, 1H), 2.86 (dd, J = 16.9, 8.2Hz, 1H).

[0064] 13 C NMR (150 MHz, DMSO-d 6 )δ32.1,48.4,86.3,110.2,115.1,122.6,122.9,125.1,125.2,128.7,131.2,142.7,157.0,174.4,175.3

[0065] HRMS(ESI)Calculated for C 17 H 13 NO 4 [M+H] + =296.0919,Found 296.0917.

[0066] HPLC(CHIRALPAK IG,n-hexane / IPA(4:1),0.8mL / min,210nm):(+)-1,t R =22.3min,(-)-1,

[0067] t R =26.4min.(+)-1:(-)-1=1:1.

[0068]

[0069] Compound 7′-epi-(±)-1: TLC (SiO 2 ):R f =0.42 (petroleum ether:ethyl acetate=1:1).

[0070] 1 H NMR (600 MHz, DMSO-d 6)δ10.70(s,1H),9.39(s,1H),7.15(td,J=7.7,1.2Hz,1H),7.01(dd,J=7.7,1.2Hz,1H),6.86(d,J=8.6Hz,2H),6.80(td,J=7.7,1.0Hz ,1H),6.74(d,J=7.7Hz,1H),6.56(d,J=8.6Hz,2H),4.05(t,J=9.1Hz,1H),3.47(dd,J=17.6,9.8Hz,1H),3.21(dd,J=17.6,8.5Hz,1H).

[0071] 13 C NMR (150 MHz, DMSO-d 6 )δ32.7,46.7,86.1,110.3,115.1,121.8,124.4,125.6,125.9,128.7,130.6,142.0,156.7,174.7,175.6

[0072] HRMS(ESI)Calculated for C 17 H 13 NO 4 [M+H] + =296.0925,Found 296.0917

[0073] HPLC(CHIRALPAK IG,n-hexane / IPA(5:1),0.8mL / min,210nm):7′-epi-(-)-1,t R =11.3min,

[0074] 7′-epi-(+)-1,t R =15.5min.7′-epi-(-)-1:7′-epi-(+)-1=1:1.

[0075] Embodiment 3:

[0076] The preparation of new spiro-oxindole alkaloid compounds 2 and 3 was carried out as follows:

[0077] Tryptophan methyl ester hydrochloride (218 mg, 1 mmol), isatin (123 mg, 0.83 mmol) and trifluoroacetic acid TFA (22.8 mg, 0.2 mmol) were added to a dry sealed pressure tube equipped with a magnetic stirrer, dissolved in anhydrous methanol (15 mL), sealed with a threaded plug, moved to 90 ° C, reacted for 1 h, and after the reaction was completed by TLC monitoring, the solvent was dried under reduced pressure, the mixture was dissolved with ethyl acetate (15.0 mL), and saturated sodium bicarbonate (5.0 mL) solution was added to quench the reaction. The mixture was extracted with ethyl acetate (3×15.0 mL), and then the combined organic phase was washed with saturated NaCl aqueous solution (2×15.0 mL), and then washed with anhydrous MgSO 4 Dry and remove the solvent to obtain a crude product. Column chromatography (SiO 2 , dichloromethane:methanol=100:1) to obtain light yellow solid compound 2 (yield 11%) and compound 3 (yield 81%).

[0078]

[0079] 2: 1 HNMR (600 MHz, DMSO-d 6 )δ10.82(s,1H),10.69(s,1H),7.49(d,J=7.8Hz,1H),7.27(td,J=7.7,1.2Hz,1H),7.2 5(d,J=7.6Hz,1H),7.17(dt,J=8.0,0.9Hz,1H),7.05(ddd,J=8.2,7.0,1.2Hz,1H),6.99 (ddd,J=7.8,5.8,1.1Hz,2H),6.90(td,J=7.5,1.1Hz,1H),4.24(td,J=11.0,4.4Hz,1H ), 3.20(dd,J=15.2,4.4Hz,1H), 2.85(dd,J=15.2,10.9Hz,1H), 2.48(d,J=11.6Hz,2H).

[0080] 13 C NMR (150 MHz, DMSO-d 6 )δ24.9,52.1,52.7,62.0,108.7,110.5,111.3,118.0,118.8,121.8,122.0,124.8,126.0,129.4,130.5,132.6,136.5,141.8,172.6,176.4

[0081] HRMS(ESI)Calculated for C 20 H 17 N3 O 3 [M+H] + =348.1345,Found 348.1343

[0082]

[0083] 3: 1 H NMR (600 MHz, DMSO-d 6 )δ10.49(s,1H),10.48(s,1H),7.49(dd,J=7.8,1.2Hz,1H),7.30(td,J=7.7,1.3Hz,1H),7.18(d t,J=8.0,1.0Hz,1H),7.13(dd,J=7.4,1.3Hz,1H),7.04(ddd,J=8.1,7.0,1.3Hz,1H),6.99(ddd,J =7.8,6.9,1.1Hz,1H),6.97(td,J=7.4,1.0Hz,0H),6.95(d,J=7.6Hz,1H),4.75(ddd,J=11.2,6.9 ,4.2Hz,1H),3.24(d,J=6.9Hz,1H),3.11(dd,J=15.0,4.2Hz,1H),2.90(dd,J=15.0,11.2Hz,1H).

[0084] 13 C NMR (150 MHz, DMSO-d 6 )δ25.0,51.6,51.9,61.1,109.4,110.0,111.3,117.9,118.7,121.5,121.9,124.9,126.3,129.6,131.3,131.3,136.5,142.8,172.9,178.3

[0085] HRMS(ESI)Calculated for C 20 H 17 N 3 O 3 [M+H] + =348.1351,Found 348.1343

[0086] Example 4: Detection of the effects of compounds 1-3 on HT22 cell viability

[0087] The CCK-8 method was used for detection. HT22 cells in the logarithmic growth phase were taken and 1×10 4Each well was inoculated in a 96-well plate. After culturing for 12 hours, glutamate Glu (final concentration of 5mM) and compounds (3.125, 6.25, 12.5, 25, 50μM) were added. A control group (Con) and blank wells (corresponding amounts of cell culture fluid and CCK-8 solution) were set up. Each well had 5 replicate wells. After culturing in an incubator for 6 hours, 10μL of CCK-8 solution was added to each well (100μL of culture medium per well). After incubation in an incubator for 2 hours, the absorbance value (A) of each well was measured at a wavelength of 450nm on an ELISA reader to calculate the survival rate of each experimental well. Survival rate = (A 实验组 -A 空白组 ) / (A 对照组 -A 空白组 )×100%, the experiment was repeated 3 times.

[0088] Table 2 Protective effect of compounds 1-3 on Glu-induced neurotoxicity in HT22 cells (survival rate %)

[0089]

Claims

1. Spirooxindole alkaloids from Polygonum tinctorium, characterized in that It is any one of the structures shown in the following structural formula:

2. The spirooxindole alkaloids in Polygonum tinctorium according to claim 1, characterized in that The indigo plant refers to Persicaria tinctoria (Aiton) Spach, a plant of the genus Polygonum in the Polygonaceae family.

3. The method for separating and preparing spirooxindole alkaloids in Polygonum tinctorium according to claim 1 or claim 2, characterized in that: The steps include: The dried leaves of Polygonum indigofera were extracted with ethanol reflux, and the extracts were combined and concentrated to obtain an extract. The extract was extracted with dichloromethane and the obtained components were subjected to silica gel column chromatography and isocratic gradient elution was performed with a dichloromethane-methanol system of 100:1-1:1, and a total of 4 fractions AD were collected; Fractions A and B were subjected to HP20 column chromatography, gradient eluted with an ethanol-water system of 0:100-100:0, and two components A1 and A2 were obtained respectively; for B1 and B2, components A1 and B2 were gradient eluted with an ethanol-water system of 30:70-90:10 using ODS column chromatography, and three components A1-1-A1-3 and B2-1-B2-3 were obtained respectively. The obtained component A1-3 was subjected to silica gel column chromatography with a dichloromethane-methanol system of 100:1-30:1, and four subcomponents a1-a4 were obtained on the basis of TLC analysis. The obtained component B2-3 was subjected to silica gel column chromatography with a dichloromethane-methanol system of 50:1-20:1, and four subcomponents b1-b4 were obtained on the basis of TLC analysis. On preparative reverse-phase HPLC, methanol-water mobile phase was used to separate a4 to obtain compound 1. On an IG chiral chromatographic column, hexane-isopropanol mobile phase was used to split compound 1 to obtain (+)-1 and (-)-1. On preparative reverse-phase HPLC, methanol-water mobile phase was used to separate b4 to obtain compounds 2 and 3.

4. The method for separating and preparing spirooxindole alkaloids in Polygonum tinctorium according to claim 3, characterized in that: The dried leaves of Polygonum indigofera were extracted with 70-80% ethanol under reflux for 3-4 times, each time for 2-3 h, and a4 was separated with a 50:50 methanol-water mobile phase, b4 was separated with a 60:40 methanol-water mobile phase, and compound 1 was separated with a 5:1 n-hexane-isopropanol mobile phase.

5. The biomimetic synthesis preparation method of the spirooxindole alkaloid compound 1 in Polygonum indigofera according to claim 1 or claim 2, characterized in that: The steps include: 3-Hydroxyindolinone and trans-p-coumaric acid methyl ester, a solvent and a catalyst are added to a sealed tube equipped with a magnetic pole, and an inert gas is introduced after sealing. The reaction is stirred at a reflux temperature for 16 to 24 hours, and the solvent is removed under reduced pressure to obtain a crude product; the crude product is purified by column chromatography to obtain spirooxindole alkaloid compounds 1 and 7′-epi-(±)-1; and enantiomers (+)-1 and (-)-1, 7′-epi-(+)-1 and 7′-epi-(-)-1 are obtained by chiral separation.

6. The biomimetic synthesis preparation method of the spirooxindole alkaloid compounds 1 and 7′-epi-(±)-1 in Polygonum tinctorium according to claim 5, characterized in that: The solvent is p-xylene, the catalyst is ruthenium dodecacarbonyl, 1,3-bis(diphenylphosphino)propane (DPPP) and potassium tert-butoxide, and the crude product is separated by column chromatography using petroleum ether-ethyl acetate in a ratio of 3:1-2:

1.

7. A biomimetic synthesis method for preparing the spirooxindole alkaloid compound 2 and compound 3 in Polygonum indigofera according to claim 1 or claim 2, characterized in that: The steps include: D-tryptophan methyl ester hydrochloride and isatin were added to a sealed tube equipped with a magnetic bar, dissolved in anhydrous methanol, TFA was added, stirred for 10 minutes, and then moved to 90°C for reaction. The solvent was removed under reduced pressure to obtain a crude product; the crude product was purified by column chromatography to obtain spirohydroxyindole alkaloid compounds 2 and 3.

8. The biomimetic synthesis preparation method of spirooxindole alkaloid compound 2 and compound 3 in Polygonum indigofera according to claim 7, characterized in that: The reflux time was 0.5-1 h, and the crude product was separated by column chromatography using dichloromethane-methanol in a ratio of 100:0-80:

1.

9. A pharmaceutical composition, characterized in that The spirohydroxyindole alkaloid or a pharmaceutically acceptable salt thereof according to claim 1 or claim 2 or claim 5 or claim 7 is used as an active ingredient and mixed with a pharmaceutically acceptable excipient to prepare a composition, wherein the composition is a clinically acceptable dosage form, which is an injection, a tablet or a capsule.

10. Use of the spirooxindole alkaloid or pharmaceutically acceptable salt thereof according to claim 1 or claim 2 or claim 5 or claim 7 or the pharmaceutical composition according to claim 9 in the preparation of a medicament for preventing and / or treating a neurodegenerative disease, wherein the medicament has a neuroprotective effect.

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