Sesquiterpene compound, preparation method and application of sesquiterpene compound as acetylcholin esterase inhibitor

Abstract

The invention discloses a sesquiterpene compound, a preparation method and application of the sesquiterpene compound as an acetylcholin esterase inhibitor. According to the invention, a compound physochlatone A with a novel structure is obtained through separation, molecular docking is carried out on the compound and acetylcholin esterase, the binding activity of the compound and acetylcholin esterase is simulated, and the binding energy is-9.6 kcal / mol; a blood-brain barrier permeability prediction result shows that the compound can pass through a blood-brain barrier; an acetylcholin esterase inhibitory activity evaluation result shows that the compound has obvious acetylcholin esterase inhibitory activity. Technicians in the field know that significant decline of the acetylcholine level is one of the important causes causing various neurodegenerative diseases, and the decline of the acetylcholine level can be inhibited by inhibiting the activity of acetylcholin esterase, so that the effect of resisting the neurodegenerative diseases is achieved. Therefore, the physochlatone A has the prospect of being developed into the medicine for resisting the neurodegenerative diseases (such as the Alzheimer's disease).

Description

Technical Field

[0001] The present invention belongs to the field of medicinal chemistry and relates to the preparation and use of new compounds, and in particular to a sesquiterpene compound, a preparation method and use thereof as an acetylcholinesterase inhibitor. Background Art

[0002] Acetylcholinesterase (AChE) is a key hydrolase present in the synaptic cleft of cholinergic neurons. Its core function is to catalyze the hydrolysis of the neurotransmitter acetylcholine (ACh) and terminate nerve signal transmission. A significant decrease in acetylcholine levels is one of the causes of various neurodegenerative diseases, especially Alzheimer's disease (AD). Based on this "cholinergic hypothesis", inhibiting AChE activity, reducing ACh hydrolysis, and thus increasing the ACh concentration in the synaptic cleft has become one of the important therapeutic strategies for improving AD. However, the AChE inhibitors currently used in clinical practice are often accompanied by some side effects. For example, galantamine has serious adverse reactions such as bradycardia, heart failure, esophageal perforation, gastrointestinal bleeding, and thrombocytopenia [Liang Zhi, Fan Linlin, Li Hongliang, et al. Current status and new progress in drug treatment of Alzheimer's disease [J]. Southwest National Defense Medicine, 2018, 28(01): 85-87]. Therefore, finding new, highly effective, and low-toxic AChE inhibitors, especially exploring molecules with unique structures and mechanisms of action from natural products, is an important direction and urgent need in the field of drug research and development.

[0003] Huashan ginseng is the dried root of Physochlaina infundibularis Kuang, a plant of the Solanaceae family. It was first described in the Supplement to Compendium of Materia Medica and was included in the Chinese Pharmacopoeia in 2010. Huashan ginseng has the effects of warming the lungs and eliminating phlegm, relieving asthma and cough, and calming the nerves. Modern pharmacological research has revealed its analgesic, sedative, and anti-inflammatory properties. Phytochemical studies have shown that Huashan ginseng contains a variety of active ingredients, including alkaloids, flavonoids, and coumarins.

[0004] The present invention isolates a new compound from Panax notoginseng, which is discovered for the first time. The present invention also finds that the compound has obvious biological activity, and thus proposes the present invention. Summary of the Invention

[0005] The first purpose of the present invention is to provide a new sesquiterpene compound, the second purpose is to provide a method for preparing the compound, and the third purpose is to provide uses of the compound.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0007] A sesquiterpene compound of the following structural formula or a pharmaceutically acceptable salt or solvate thereof:

[0008]

[0009] A method for preparing the above-mentioned sesquiterpene compound comprises the following steps:

[0010] S1. Grind the Chinese ginseng, extract it with ethanol and water, filter it, and concentrate the filtrate under reduced pressure to obtain a crude extract; resuspend the crude extract in water to prepare a suspension, extract it with an equal volume of ethyl acetate, and concentrate the organic phase under reduced pressure to obtain an ethyl acetate extract; extract the remaining aqueous phase with an equal volume of n-butanol, and concentrate the organic phase under reduced pressure to obtain an n-butanol extract;

[0011] S2. The ethyl acetate extract was loaded onto a macroporous adsorption resin column chromatography, and gradient eluted with a methanol-water mixed solvent in different ratios to obtain five fractions Fr.A to Fr.E. Fraction Fr.D was used for subsequent separation; wherein the gradient elution ratio, volume, and sequence of the macroporous adsorption resin column chromatography were as follows: 0:100 elution for 1 column volume → 30:70 elution for 3 column volumes → 50:50 elution for 3 column volumes → 80:20 elution for 4 column volumes → 100:0 elution for 3 column volumes;

[0012] S3. Load fraction Fr.D onto normal phase silica gel column chromatography, and gradient elute with a petroleum ether-ethyl acetate mixed solvent. Detect and combine the fractions by TLC to obtain seven fractions, Fr.D.1 to D.7. Fraction Fr.D.2 is used for subsequent separation. The gradient elution ratio, volume, and sequence of the normal phase silica gel column chromatography are as follows: 10:1 elution for 2 column volumes → 8:1 elution for 3 column volumes → 5:1 elution for 3 column volumes → 3:1 elution for 4 column volumes → 2:1 elution for 4 column volumes → 1:1 elution for 3 column volumes → methanol elution for 2 column volumes.

[0013] S4. Load fraction Fr.D.2 onto normal phase silica gel column chromatography, and gradient elute with a petroleum ether-ethyl acetate mixed solvent. Detect and combine the fractions by TLC to obtain six fractions Fr.D.2.1 to Fr.D.2.6. Fraction Fr.D.2.1 is used for subsequent separation. The gradient elution ratio, volume, and order of normal phase silica gel column chromatography are as follows: 10:1 elution for 2 column volumes → 7:1 elution for 3 column volumes → 5:1 elution for 4 column volumes → 3:1 elution for 4 column volumes → 1:1 elution for 3 column volumes → methanol elution for 2 column volumes.

[0014] S5. Load Fr.D.2.1 onto an ODS reverse-phase column chromatography column and perform gradient elution with a methanol-water mixed solvent of different proportions to obtain seven fractions, Fr.D.2.1.1 to Fr.D.2.1.7. Fraction Fr.D2.1.2 is used for subsequent separation. The gradient elution ratio, volume, and sequence of the ODS reverse-phase column chromatography are as follows: 0:100 for 1 column volume → 30:70 for 3 column volumes → 40:60 for 3 column volumes → 50:50 for 3 column volumes → 60:40 for 3 column volumes → 80:20 for 3 column volumes → 100:0 for 2 column volumes.

[0015] S6. Load Fr.D2.1.2 onto a Sephadex LH-20 column, isocratically elute with methanol, and combine the fractions detected by TLC to obtain three fractions, Fr.D2.1.2.1 to Fr.D2.1.2.3, of which the Fr.D2.1.2.2 fraction is used for subsequent separation;

[0016] S7. The Fr.D2.1.2.2 fraction was subjected to preparative HPLC chromatography with isocratic elution using methanol-water in a volume ratio of 51:49, and the fractions at the peak of Panax notoginseng lactone A were collected and concentrated to dryness.

[0017] Preferably, the ethanol aqueous solution in step S1 is an ethanol aqueous solution with an ethanol volume fraction of 80%.

[0018] Preferably, the extraction temperature in step S1 is 90°C.

[0019] Preferably, the model of the macroporous adsorption resin is HP-20.

[0020] The sesquiterpene compound or its pharmaceutically acceptable salt or solvate is used for preparing acetylcholinesterase inhibitor drugs.

[0021] Use of the above-mentioned sesquiterpene compound or its pharmaceutically acceptable salt or solvate for preparing a drug for treating neurodegenerative diseases.

[0022] Preferably, the neurodegenerative disease is Alzheimer's disease.

[0023] Preferably, the drug uses the sesquiterpene compound or a pharmaceutically acceptable salt or solvate thereof as an active ingredient and is prepared into a pharmaceutically acceptable dosage form with pharmaceutically acceptable excipients.

[0024] More preferably, the excipient is solid, liquid or semisolid, and the dosage form is tablet, capsule, injection or pill.

[0025] Beneficial effects:

[0026] The present invention isolates a novel structural compound, physochlatone A, and performs molecular docking on the compound and acetylcholinesterase (AChE, PDB: 1EVE) to simulate the binding activity of the two, with a binding energy of -9.6 kcal / mol; the blood-brain barrier permeability prediction results show that the compound can pass through the blood-brain barrier; the acetylcholinesterase inhibitory activity evaluation results show that the compound has obvious acetylcholinesterase inhibitory activity. It is known to those skilled in the art that a significant decrease in acetylcholine levels is one of the important causes of a variety of neurodegenerative diseases. Inhibiting acetylcholinesterase activity can inhibit the decrease in acetylcholine levels, thereby exerting an anti-neurodegenerative effect. Therefore, the compound physochlatone A discovered by the present invention has the prospect of being developed into a drug for anti-neurodegenerative diseases (such as Alzheimer's disease). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the HR-ESI-MS spectrum of compound physochlatoneA;

[0028] Figure 2 For the compound physochlatone A 1 H NMR spectrum (500 MHz, CD3OD);

[0029] Figure 3 For the compound physochlatone A 13 C NMR spectrum (500 MHz, CD3OD);

[0030] Figure 4 DEPT135 and 13 C NMR comparison chart (500 MHz, CD3OD);

[0031] Figure 5 HSQC spectrum of compound physochlatone A (500 MHz, CD3OD);

[0032] Figure 6 is the HMBC spectrum of compound physochlatone A (500 MHz, CD3OD);

[0033] Figure 7 For the compound physochlatone A 1 H- 1 H COSY spectrum (500 MHz, CD3OD);

[0034] Figure 8NOESY spectrum of compound physochlatone A (500 MHz, CD3OD);

[0035] Figure 9 HMBC and 1 H- 1 H COSY correlation diagram;

[0036] Figure 10 is the ECD diagram of compound physochlatoneA;

[0037] Figure 11 DP4+ calculation analysis of compound physochlatoneA;

[0038] Figure 12 Schematic diagram of the predicted interaction between compound physochlatoneA and 1EVE (the yellow dashed line represents the hydrogen bond);

[0039] Figure 13 Schematic diagram of the BBB permeability prediction of compound physochlatone A (the arrow points to the BBB region). DETAILED DESCRIPTION

[0040] The essential contents of the present invention are described in detail below with reference to the embodiments, but the protection scope of the present invention is not limited thereto.

[0041] Huashan ginseng was collected in Pingdingshan City, Henan Province (2021.09), and was later identified by Professor Li Jun of the Academy of Traditional Chinese Medicine of Henan University of Traditional Chinese Medicine as the dried root of Physochlaina infundibularis Kuang, a plant of the Solanaceae family.

[0042] Example 1: Isolation and identification of a sesquiterpenoid compound (named physochlatone A)

[0043] 1. Extraction and separation

[0044] 60 kg of collected Chinese ginseng were crushed, extracted twice with 80% by volume ethanol aqueous solution at 90°C for 2 hours each time, the extracts were combined, filtered, and the filtrate was concentrated under reduced pressure to obtain a crude extract; the crude extract was added to distilled water to prepare a suspension and extracted three times with an equal volume of ethyl acetate, the organic phase was concentrated under reduced pressure at 40°C using a rotary evaporator to obtain an ethyl acetate extraction portion, the remaining aqueous phase was extracted three times with an equal volume of n-butanol, the organic phase was concentrated under reduced pressure at 40°C using a rotary evaporator to obtain an n-butanol extraction portion.

[0045] The ethyl acetate extraction portion was loaded onto a macroporous adsorption resin column chromatography, the macroporous resin model was HP-20, and gradient elution was performed with a methanol-water mixed solvent in different proportions to obtain five fractions Fr.A to Fr.E, and fraction Fr.D was used for subsequent separation; wherein, the gradient elution ratio, volume and sequence of the macroporous adsorption resin column chromatography were: 0:100 elution for 1 column volume → 30:70 elution for 3 column volumes → 50:50 elution for 3 column volumes → 80:20 elution for 4 column volumes → 100:0 elution for 3 column volumes.

[0046] The fraction Fr.D was loaded onto normal phase silica gel column chromatography and gradient eluted with a mixed solvent of petroleum ether and ethyl acetate. The fractions were detected and combined by TLC to obtain 7 fractions Fr.D.1 to D.7. The fraction Fr.D.2 was used for subsequent separation. Among them, the gradient elution ratio, volume and sequence of normal phase silica gel column chromatography were: 10:1 elution for 2 column volumes → 8:1 elution for 3 column volumes → 5:1 elution for 3 column volumes → 3:1 elution for 4 column volumes → 2:1 elution for 4 column volumes → 1:1 elution for 3 column volumes → methanol elution for 2 column volumes.

[0047] The fraction Fr.D.2 was loaded onto normal phase silica gel column chromatography and gradient eluted with a mixed solvent of petroleum ether and ethyl acetate. The fractions were detected and combined by TLC to obtain 6 fractions Fr.D.2.1 to D.2.6. The Fr.D.2.1 fraction was used for subsequent separation. Among them, the gradient elution ratio, volume and sequence of normal phase silica gel column chromatography were: 10:1 elution for 2 column volumes → 7:1 elution for 3 column volumes → 5:1 elution for 4 column volumes → 3:1 elution for 4 column volumes → 1:1 elution for 3 column volumes → methanol elution for 2 column volumes.

[0048] Fr.D.2.1 was loaded onto ODS reverse-phase column chromatography and gradient eluted with methanol-water mixed solvents in different proportions to obtain 7 fractions Fr.D.2.1.1 to Fr.D.2.1.7, and fraction Fr.D2.1.2 was used for subsequent separation; among them, the gradient elution ratio, volume and sequence of ODS reverse-phase column chromatography were: 0:100 elution for 1 column volume → 30:70 elution for 3 column volumes → 40:60 elution for 3 column volumes → 50:50 elution for 3 column volumes → 60:40 elution for 3 column volumes → 80:20 elution for 3 column volumes → 100:0 elution for 2 column volumes.

[0049] Fr.D2.1.2 was loaded onto a Sephadex LH-20 column, isocratically eluted with methanol, and combined by TLC detection to obtain three fractions Fr.D2.1.2.1 to Fr.D2.1.2.3, of which the Fr.D2.1.2.2 fraction was used for subsequent separation.

[0050] The Fr.D2.1.2.2 fraction was subjected to preparative HPLC chromatography with isocratic elution using methanol-water in a volume ratio of 51:49. The fractions at the peak of sphenanthenolide A were collected and concentrated to obtain sphenanthenolide A.

[0051] 2. Structural identification of Physochlatone A

[0052] Colorless oil, HR-ESI-MS m / z=249.1121[M+H] + (The calculated value is 249.1121) (such as Figure 1 As shown), the molecular formula is C 14 H 16 O4 (combined 1 H and 13 C-NMR data), the unsaturation degree of the compound is 7. 1 In the H-NMR spectrum ( Figure 2 ), δ H 5.16 (1H, d, J = 4.5 Hz, H-3) is the proton signal of the oxygen-linked methine; δ H 4.84 (2H, s, H2-12) is the signal of two protons on the terminal double bond of group 1; δ H 3.22 (1H, dd, J = 18.0, 4.5 Hz, H-4a), 2.93 (1H, ddt, J = 19.3, 8.9, 1.8 Hz, H-9a), 2.79 (1H, d, J = 18.0 Hz, H-4b), 2.49 (1H, ddd, J = 19.3, 10.4, 2.0 Hz, H-9b), 1.89 (1H, d, J = 14.0 Hz, H-7b), 2.22 (1H, ddt, J = 13.3, 5.6, 1.2 Hz, H-7a) are the proton signals of three groups of methylene; one methine proton signal δ H 3.08 (1H, m, H-8); 2 groups of methyl proton signals δ H 1.91 (3H, s, H3-13) and 1.80 (3H, s, H3-14). 13 C-NMR spectrum ( Figure 3 ) showed 14 carbon signals, and combined with DEPT( Figure 4 ) and HSQC( Figure 5 ) spectrum, and the 14 carbon signals were assigned to 2 carbonyl carbon signals δ C 175.3 (C-5) and 164.9 (C-2); 4 olefin carbon signals δ C 152.8 (C-10), 146.6 (C-11), 125.8 (C-1) and 110.8 (C-12); 1 oxygen-linked quaternary carbon signal δ C 87.5(C-6);δC 80.9 (C-3) is the methine carbon signal connected to the oxygen atom; the three methylene carbon signals δ C 42.1 (C-7), 38.1 (C-4) and 34.7 (C-9); 1 methine carbon signal δ C 44.3 (C-8); 2 methyl carbon signals δ C 21.1(C-13) and 13.4(C-14).

[0053] 1 H- 1 H COSY( Figure 7 ) spectrum showed H2-7 / H-8 / H2-9 correlation; and HMBC ( Figure 6 ) spectrum, H2-9 correlated with C-10 and C-6, and H2-7 correlated with C-10 and C-6, confirming the presence of a five-membered ring (Ring A) consisting of C-6—C-7—C-8—C-9—C-10. H3-13 correlated with C-12, C-11, and C-8, and H2-12 correlated with C-8, indicating the presence of an isopropenyl group attached to C-8. 1 H- 1 The H COSY spectrum showed that H-3 / H2-4 were correlated, and in the HMBC spectrum, the correlations of H-3 / C-5, C-6 and H2-4 / C-5 confirmed the existence of a five-membered lactone ring (C ring). Further, through the correlation of H-3 / C-7, it was determined that ring A and ring C were connected through C-6. The HMBC spectrum showed that H3-14 was correlated with C-1, C-2, and C-10, and H2-4 was correlated with C-2. Combined with the unsaturation of the compound, it was determined that it had an unsaturated lactone ring (B ring), and ring A and ring B were connected through C-6 and C-10, and ring B and ring C were connected through C-3 and C-6. So far, the planar structure of the compound has been determined, as shown in Figure 2. Figure 9 shown.

[0054] The absolute configuration of the compound was determined by comparing the measured electron circular dichroism (ECD) curve of the compound with the calculated ECD curve. The ECD curve of the compound was calculated at the b3lyp / 6-31g+(d,p) level using the PCM solvation model with a dielectric constant of methanol. Figure 10 As shown in Figure 2, the calculated ECD curves of (3R,6R,8R)-1 and (3R,6R,8S)-1 fit well with the measured ECD curve of compound physochlatoneA. Therefore, the absolute configuration of C-3 and C-6 of compound physochlatoneA was determined to be 3R,6R. In order to determine the absolute configuration of C-8, the calculated ECD curves of (3R,6R,8R)-1 and (3R,6R,8S)-1 were calculated. 13CNMR chemical shift results showed (3R,6R,8R)-1( 13 C data: R 2 =0.9989) matches the experimental data better than (3R,6R,8S)-1( 13 C data: R 2 =0.9986). In addition, according to DP4+ probability analysis, the probability of (3R,6R,8R)-1 is higher than that of (3R,6R,8S)-1 (99.62 vs 0.38%) ( Figure 11 ). In summary, the absolute configuration of compound physochlatone A was determined to be 3R, 6R, 8R.

[0055] The carbon and hydrogen signal assignments of compound physochlatone A are shown in Table 1.

[0056] Table 1 Compounds 1 H(500MHz) and 13 C (125 MHz) NMR data (CD3OD)

[0057]

[0058] Example 2: Molecular docking study of Physochlatone A and acetylcholinesterase

[0059] Ligand: The target compound was downloaded from the PubChem database (https: / / pubchem.ncbi.nlm.nih.gov / ). The molecular structure was optimized using energy minimization (MM2 force field in Chemdraw 3D). After optimization, the file was saved in mol2 format and then converted to pdbqt format using AutoDockTools to serve as the ligand file for molecular docking. Receptor: The crystal structure file of the target protein acetylcholinesterase (PDB ID: 1EVE) was downloaded from the RCSB Protein Data Bank (https: / / www.rcsb.org / ). Small molecules and water molecules were removed using UCSF Chimera. After hydrogenation, the structure was saved in pdb format and converted to pdbqt format using AutoDockTools to serve as the receptor file for molecular docking. Docking grid (Grid Box) settings: Using AutoDockTools, the center coordinates and size of the docking grid (GridBox) were set to ensure that the grid covered the protein active site. The center coordinates (x, y, z) and size (length, width, height) of the GridBox were also recorded for subsequent docking calculations. Molecular docking calculations: Molecular docking calculations were performed using AutoDock Vina. Receptor (pdbqt format) and ligand (pdbqt format) files were imported into Vina, along with the recorded grid box information. The docking parameters were set appropriately to run the docking calculation. After docking, the results were visualized using PyMOL, and the interaction pattern and binding free energy of the ligand and receptor were analyzed.

[0060] The binding mode of compound Physochlatone A to 1EVE protein is as follows Figure 12 As shown, the two form a suitable steric complement. The carbonyl oxygen atom of Physochlatone A forms hydrogen bonds with the hydrogen atoms of GLY-118 and GLY-119, respectively; the oxygen atom of the ester bond forms a hydrogen bond with the hydroxyl hydrogen atom of TYR-121. The binding energy of Physochlatone A to 1EVE is -9.6 kcal / mol.

[0061] Example 3: Prediction of blood-brain barrier permeability of Physochlatone A

[0062] By inputting the compound structure into the Swiss Target Prediction tool (http: / / swisstargetprediction.ch / ), the target to which the compound may bind can be predicted. Combined with the known blood-brain barrier-related target information, it can be inferred whether the compound is likely to pass through the blood-brain barrier.

[0063] like Figure 13 As shown in the figure, the compound physochlatone A is located in the BBB area that can pass through the blood-brain barrier, indicating that the compound physochlatone A has good blood-brain barrier permeability.

[0064] Example 4: Acetylcholinesterase inhibitory activity of compound physochlatone A

[0065] Ellman method: 140 μL of PBS buffer (0.1 M, pH 8.0), 20 μL of sample solution (1 μM, 10 μM, and 100 μM), and 15 μL of AChE solution (0.28 U / mL, diluted in PBS, pH 8.0) were sequentially added to a 96-well plate and incubated (4°C) for 20 minutes. Then, 10 μL each of DTNB (0.075 mol / L) and ATCI (0.01 mol / L) solutions were added to the 96-well plate. After incubation (37°C) for 20 minutes, absorbance was measured using a microplate reader (405 nm). Inhibition was calculated according to the following formula.

[0066] Inhibition rate (%) = [(blank group - positive group) - (experimental group - background reaction group)] / (blank group - positive group) × 100%.

[0067] Among them, 20 μL sample solution in the blank group was replaced by 20 μL PBS (pH = 8.0); 20 μL sample solution in the positive group was replaced by 20 μL galanthamine (0.125 mg / ml); 15 μL AChE (0.28 U / ml, pH = 8.0 dissolved and diluted in PBS) in the background reaction group was replaced by 15 μL PBS (pH = 8.0).

[0068] The inhibition rate results are shown in Table 2.

[0069] Table 2 Anti-acetylcholinesterase results ( n=3)

[0070]

[0071] The experimental results show that the compound physochlatone A has acetylcholinesterase inhibitory activity and has application prospects in developing into an acetylcholinesterase inhibitor.

[0072] In summary, the present invention isolates a novel structural compound physochlatone A, performs molecular docking on the compound and acetylcholinesterase (AChE, PDB: 1EVE), simulates the binding activity of the two, and the binding energy is -9.6kcal / mol; the blood-brain barrier permeability prediction results show that the compound can pass through the blood-brain barrier; the acetylcholinesterase inhibitory activity evaluation results show that the compound has obvious acetylcholinesterase inhibitory activity. It is known to those skilled in the art that a significant decrease in acetylcholine levels is one of the important causes of a variety of neurodegenerative diseases. Inhibiting acetylcholinesterase activity can inhibit the decrease in acetylcholine levels, thereby exerting an anti-neurodegenerative effect. Therefore, the compound physochlatoneA discovered in the present invention has the prospect of being developed into a drug for anti-neurodegenerative diseases (such as Alzheimer's disease).

[0073] The purpose of the above embodiments is to specifically introduce the essential content of the present invention, but those skilled in the art should know that the protection scope of the present invention should not be limited to this specific embodiment.

Claims

1. A sesquiterpene compound of the following structural formula or a pharmaceutically acceptable salt or solvate thereof:

2. A method for preparing the sesquiterpene compound according to claim 1, characterized in that: The steps include: S1. Grind the Chinese ginseng, extract it with ethanol and water, filter it, and concentrate the filtrate under reduced pressure to obtain a crude extract; resuspend the crude extract in water to prepare a suspension, extract it with an equal volume of ethyl acetate, and concentrate the organic phase under reduced pressure to obtain an ethyl acetate extract; extract the remaining aqueous phase with an equal volume of n-butanol, and concentrate the organic phase under reduced pressure to obtain an n-butanol extract; S2. The ethyl acetate extract was loaded onto a macroporous adsorption resin column chromatography, and gradient eluted with a methanol-water mixed solvent in different ratios to obtain five fractions Fr.A to Fr.E. Fraction Fr.D was used for subsequent separation; wherein the gradient elution ratio, volume, and sequence of the macroporous adsorption resin column chromatography were as follows: 0:100 elution for 1 column volume → 30:70 elution for 3 column volumes → 50:50 elution for 3 column volumes → 80:20 elution for 4 column volumes → 100:0 elution for 3 column volumes; S3. Load fraction Fr.D onto normal phase silica gel column chromatography, and gradient elute with a petroleum ether-ethyl acetate mixed solvent. Detect and combine the fractions by TLC to obtain seven fractions, Fr.D.1 to D.

7. Fraction Fr.D.2 is used for subsequent separation. The gradient elution ratio, volume, and sequence of the normal phase silica gel column chromatography are as follows: 10:1 elution for 2 column volumes → 8:1 elution for 3 column volumes → 5:1 elution for 3 column volumes → 3:1 elution for 4 column volumes → 2:1 elution for 4 column volumes → 1:1 elution for 3 column volumes → methanol elution for 2 column volumes. S4. Load fraction Fr.D.2 onto normal phase silica gel column chromatography, and gradient elute with a petroleum ether-ethyl acetate mixed solvent. Detect and combine the fractions by TLC to obtain six fractions Fr.D.2.1 to Fr.D.2.

6. Fraction Fr.D.2.1 is used for subsequent separation. The gradient elution ratio, volume, and order of normal phase silica gel column chromatography are as follows: 10:1 elution for 2 column volumes → 7:1 elution for 3 column volumes → 5:1 elution for 4 column volumes → 3:1 elution for 4 column volumes → 1:1 elution for 3 column volumes → methanol elution for 2 column volumes. S5. Load Fr.D.2.1 onto an ODS reverse-phase column chromatography column and perform gradient elution with a methanol-water mixed solvent of different proportions to obtain seven fractions, Fr.D.2.1.1 to Fr.D.2.1.

7. Fraction Fr.D2.1.2 is used for subsequent separation. The gradient elution ratio, volume, and sequence of the ODS reverse-phase column chromatography are as follows: 0:100 for 1 column volume → 30:70 for 3 column volumes → 40:60 for 3 column volumes → 50:50 for 3 column volumes → 60:40 for 3 column volumes → 80:20 for 3 column volumes → 100:0 for 2 column volumes. S6. Load Fr.D2.1.2 onto a Sephadex LH-20 column, isocratically elute with methanol, and combine the fractions detected by TLC to obtain three fractions, Fr.D2.1.2.1 to Fr.D2.1.2.3, of which the Fr.D2.1.2.2 fraction is used for subsequent separation; S7. The Fr.D2.1.2.2 fraction was subjected to preparative HPLC chromatography with isocratic elution using methanol-water in a volume ratio of 51:49, and the fractions corresponding to the elution peak were collected and concentrated to dryness.

3. The preparation method according to claim 2, wherein: The ethanol aqueous solution in step S1 is an ethanol aqueous solution with an ethanol volume fraction of 80%.

4. The preparation method according to claim 2, wherein: The extraction temperature in step S1 is 90°C.

5. The preparation method according to claim 2, wherein: The model of the macroporous adsorption resin is HP-20.

6. Use of the sesquiterpene compound according to claim 1 or a pharmaceutically acceptable salt or solvate thereof for preparing an acetylcholinesterase inhibitor.

7. Use of the sesquiterpene compound according to claim 1 or a pharmaceutically acceptable salt or solvate thereof for preparing a medicament for treating neurodegenerative diseases.

8. The use according to claim 7, characterized in that: The neurodegenerative disease is Alzheimer's disease.

9. The use according to claim 7 or 8, characterized in that: The drug uses the sesquiterpene compound or its pharmaceutically acceptable salt or solvate as an active ingredient and is prepared into a pharmaceutically acceptable dosage form with pharmaceutically acceptable excipients.

10. The use according to claim 9, characterized in that: The auxiliary material is solid, liquid or semisolid, and the dosage form is tablet, capsule, injection or pill.

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