A diterpenoid compound, and a preparation method and application thereof

Abstract

The application discloses a diterpenoid compound and a preparation method and application thereof, and belongs to the technical field of medicines.The diterpenoid compound provided by the application has a structure as shown in the following formula (I): in the formula (I), R1 is selected from hydrogen or acetoxy; R2 is selected from hydrogen, hydroxyl or methoxy; and R3 is selected from hydrogen or hydroxyl.The diterpenoid compound has high affinity to a PXR target point, has a significant anti-inflammatory effect, can activate the PXR target point in the intestinal tract, regulate the level of inflammatory factors, has a significant effect on treating inflammatory bowel disease, and is a natural extract, has the advantages of significant curative effect and low toxicity, and has wide application in the preparation of a PXR agonist or a medicine for treating inflammatory bowel disease.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical technology, and in particular relates to a diterpenoid compound, its preparation method, and its application. Background Technology

[0002] Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a chronic, relapsing inflammatory disease characterized by intestinal homeostasis dysregulation, disruption of the intestinal epithelial barrier, increased intestinal permeability, intestinal flora imbalance, and intestinal immune system dysfunction. Current treatments for IBD include aminosalicylate, corticosteroids, antibiotics, immunomodulators, biologics, and even surgery. However, due to limited treatment efficacy, high economic costs, and significant side effects from long-term treatment, there is an urgent need to find new and effective drugs for treating IBD. Although the exact causes of IBD are not fully understood, it is currently believed that IBD is related to alterations in intestinal epithelial barrier function and dysregulation of the mucosal immune system.

[0003] Pregnane X receptor (PXR) is a ligand-activated transcription factor primarily expressed in the liver and intestine, responsible for the expression of drug-metabolizing enzymes and transport proteins. PXR plays a crucial role in regulating intestinal homeostasis and reducing inflammation. Firstly, PXR can expel toxins from the mucus layer and maintain intestinal homeostasis through the expression of the multidrug resistance gene (MDR1) and its downstream protein, P-glycoprotein. Furthermore, PXR deficiency is a significant factor in intestinal epithelial barrier disruption and increased intestinal permeability in IBD. The mechanism by which PXR affects the intestinal barrier and permeability may be through TLR4. In addition, PXR activation inhibits the expression of downstream pro-inflammatory genes of NF-κB, including genes encoding IL-1β, IL-10, iNOS, and TNFα, indicating that PXR suppresses the inflammatory response. PXR has become a research hotspot with great potential in academia and international pharmaceutical companies. Chinese invention patent CN101896815A also discloses the compound rifaximin for activating PXR to treat chronic diseases. In addition, pregnenolone-16α-nitrile has been included in clinical trials as a PXR agonist; however, the clinical application of these compounds is limited due to safety concerns.

[0004] Compounds such as curcumin, berberine, and resveratrol have been proven to be important sources for alleviating inflammatory bowel disease (IBD). Among them, active ingredients isolated from traditional Chinese medicine (TCM) have unique advantages due to their significant efficacy and safety. Studies have shown that baicalin, scutellarin, and ginsenoside Rb1 have been identified as ligands that activate the proton pump inhibitor (PXR). Chinese invention patent CN107714692A also discloses that imperatorin from Angelica dahurica can combat enteritis by activating the PXR. Therefore, natural PXR agonists from traditional Chinese medicine may be a novel strategy for treating IBD.

[0005] Rabdosia serra (Maxim.) is a unique traditional Chinese medicine resource and a well-known ingredient in herbal teas in the Lingnan region. It is mainly distributed in southern China, including Guangdong, Fujian, Guangxi, and other subtropical and tropical regions of Asia. Rabdosia serra has the functions of clearing heat and detoxifying, and clearing heat and promoting diuresis. It can treat damp-heat jaundice and damp-heat diarrhea, and is widely used to treat acute jaundice-type hepatitis, acute cholecystitis, dysentery, enteritis, and traumatic pain. At the same time, Rabdosia serra is also one of the important raw materials for the traditional Chinese medicines Xiaoyan Lidan tablets and Fufang Dantong tablets. Rabdosia serra extract shows promise as a new strategy for treating IBD. Summary of the Invention

[0006] In order to overcome the problems existing in the prior art, one of the objectives of the present invention is to provide a diterpenoid compound that has high affinity for PXR targets and has significant anti-inflammatory effects. It can significantly treat inflammatory bowel disease by activating intestinal PXR targets and regulating the level of inflammatory factors.

[0007] A second objective of this invention is to provide a method for preparing the above-mentioned diterpenoid compounds.

[0008] A third objective of this invention is to provide a PXR agonist comprising the above-mentioned diterpenoid compounds.

[0009] A third objective of this invention is to provide a medicament for treating inflammatory bowel disease comprising the aforementioned PXR agonist.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A first aspect of the present invention provides a diterpenoid compound, the structural formula of which is shown in formula (I):

[0012]

[0013] In formula (I), R1 is selected from hydrogen or acetoxy; R2 is selected from hydrogen, hydroxyl or methoxy; R3 is selected from hydrogen or hydroxyl.

[0014] In equation (I), "---" indicates whether the key exists or does not exist.

[0015] Preferably, the compound represented by formula (I) is selected from at least one of the compounds represented by formulas (1) to (4):

[0016]

[0017] The second aspect of the present invention provides a method for preparing the diterpenoid compound described in the first aspect of the present invention, comprising the following steps: extracting *Hedyotis diffusa* using percolation to obtain an extract, and then extracting, separating and purifying the extract to obtain the diterpenoid compound.

[0018] Studies have found that *Hedyotis diffusa* extract is an effective treatment for IBD. *Hedyotis diffusa* extract can protect intestinal barrier function by improving colon length, upregulating anti-inflammatory factors, downregulating pro-inflammatory factors, restoring the balance of T helper cell regulation, and increasing tight junction proteins ZO-1 and occludin. This invention explored the high-affinity targeting signal of PXR in crude *Hedyotis diffusa* extract using affinity purification non-targeted mass spectrometry (AP-UMS), discovering a diterpenoid compound that, as a natural PXR agonist, can effectively activate PXR and promote PXR expression.

[0019] Preferably, in the preparation method, the ratio of the extraction solvent to *Hedyotis diffusa* used in the percolation method is (10-15) L: 1 kg.

[0020] Preferably, in the preparation method, the extraction solvent used in the percolation method is an alcohol solvent; more preferably, it is ethanol.

[0021] Preferably, in the preparation method, the percolation method is used to extract the *Hedyotis diffusa* 3 to 5 times.

[0022] Preferably, in the preparation method, before extracting *Hymenochloa crus-galli* using the percolation method, *Hymenochloa crus-galli* is dried and pulverized.

[0023] Preferably, the preparation method further includes a concentration and reconstitution step before extracting the extract, that is, a step of concentrating the extract to dryness and then reconstitution with water.

[0024] Preferably, in the preparation method, the extractant is an ester solvent; more preferably, ethyl acetate.

[0025] Preferably, in the preparation method, the extraction is performed 2 to 4 times.

[0026] Preferably, in the preparation method, the separation and purification are performed by sequentially eluting with a silica gel column, a dextran gel column, and a reversed-phase chromatography column.

[0027] Preferably, in the preparation method, the eluent used for elution with the silica gel column is a mixed solution of ether solvent and ester solvent; more preferably, the ether solvent is selected from petroleum ether, and the ester solvent is selected from ethyl acetate.

[0028] Preferably, in the preparation method, the volume ratio of ether solvent to ester solvent in the mixed solution is (0-6):1.

[0029] Preferably, in the preparation method, the number of elutions using the silica gel column is 3 to 5; more preferably, it is 4; and even more preferably, the eluent used in the 4 elutions using the silica gel column is a mixed solution of ether solvent and ester solvent in volume ratios of 5:1, 3:1, 1:1 and 0:1 respectively.

[0030] Preferably, in the preparation method, the volume ratio of the eluent to the eluent column when using the silica gel column for elution is 4:1.

[0031] Preferably, in the preparation method, the silica gel column is selected from normal phase silica gel columns.

[0032] Preferably, in the preparation method, the eluent used for elution with a dextran gel column is an alcohol solvent; more preferably, methanol; and even more preferably, methanol with a volume concentration of 70-90%.

[0033] Preferably, in the preparation method, the eluent used for elution with a dextran gel column is the 7th fraction obtained by elution with a silica gel column.

[0034] Preferably, in the preparation method, the dextran gel column is selected from LH-20 column.

[0035] Preferably, in the preparation method, the eluent used for elution with a reversed-phase chromatography column is the 11th component obtained by elution with a dextran gel column.

[0036] Preferably, in the preparation method, the reversed-phase chromatographic column is selected from a C18 column.

[0037] A third aspect of the present invention provides a PXR agonist comprising the diterpenoid compound described in the first aspect of the present invention.

[0038] Preferably, the active component of the PXR agonist includes the diterpenoid compound; more preferably, the active component of the PXR agonist is selected from the diterpenoid compound. The diterpenoid compound, as the sole active ingredient of the PXR agonist, can effectively activate PXR and promote PXR expression.

[0039] A fourth aspect of the present invention provides a medicament for treating inflammatory bowel disease (IBD) comprising the PXR agonist described in the third aspect of the present invention.

[0040] Preferably, the inflammatory bowel disease is ulcerative colitis (UC).

[0041] The beneficial effects of this invention are: the diterpenoid compounds of this invention have high affinity for PXR targets and have significant anti-inflammatory effects. They can significantly treat inflammatory bowel disease by activating intestinal PXR targets and regulating the level of inflammatory factors. Furthermore, as natural extracts, they have the advantages of significant efficacy and low toxicity. They have wide applications in the preparation of PXR agonists or drugs for treating inflammatory bowel disease.

[0042] Specifically, compared with the prior art, the present invention has the following advantages:

[0043] 1. PXR agonists, as a new generation of drugs for the treatment of inflammatory bowel disease, have the advantages of clear target, definite efficacy, and low toxicity. The PXR agonist of this invention is the main active ingredient in *Hedyotis diffusa*. The PXR target binding signal was first explored by affinity purification non-target mass spectrometry (AP-UMS), and a diterpenoid compound was obtained by targeted extraction by multiplex chromatography. It has high affinity for the PXR target and has significant anti-inflammatory effects. By activating the intestinal PXR target and regulating the level of inflammatory factors, it has significant therapeutic effects on inflammatory bowel disease, especially ulcerative colitis.

[0044] 2. The diterpenoid compounds of the present invention are the main active ingredients in *Hedyotis diffusa*. These compounds are natural and have high safety. As natural PXR agonists, they can safely and effectively treat inflammatory bowel disease, especially ulcerative colitis. Attached Figure Description

[0045] Figure 1 shows the proton and carbon NMR spectra of compounds 1-4 of the preparation examples of the present invention.

[0046] Figure 2 The cytotoxicity of compounds 1-4, which are examples of preparations of this invention, to HCT116 cells.

[0047] Figure 3 Compounds 1-4, which are examples of preparations of this invention, induce the activity of CYP3A4 fluorescein.

[0048] Figure 4 Compound 4, prepared as an example of this invention, is shown to alleviate DSS-induced colitis.

[0049] Figure 5 Compound 4, prepared as an example of the present invention, alleviates the level of inflammation in DSS-induced colitis.

[0050] Figure 6 The efficacy of compound 4 in activating PXR activity in the preparation example of this invention.

[0051] Figure 7 Compound 4, used in the preparation examples of this invention, induces PXR in DSS. - / - Therapeutic effect of acute colitis in mice.

[0052] Figure 8 Compound 4, used as a preparation example of this invention, is related to PXR. - / - The effect of inflammatory factor levels in mice with colitis. Detailed Implementation

[0053] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0054] Preparation Example

[0055] This example provides a method for preparing diterpenoid compounds, specifically including the following steps:

[0056] The dried and pulverized *Hedyotis diffusa* powder was extracted four times with ethanol at a material-to-liquid ratio of 1:10 (w / v). The ethanol extracts were combined, concentrated to dryness under vacuum, and then reconstituted with 10 L of ultrapure water. The reconstituted extract was extracted three times with an equal volume of ethyl acetate, and the ethyl acetate layer was collected. The ethyl acetate layer sample was purified by normal-phase silica gel column chromatography, using gradient elution with petroleum ether-ethyl acetate at volumes of 5:1 (4 column volumes), 3:1 (4 column volumes), 1:1 (4 column volumes), and 0:1 (4 column volumes), and the fractions were collected, yielding a total of 18 fractions. The 7th fraction was then separated using a dextran gel column (LH-20) with 80% methanol, and the fraction was collected. Finally, the collected 11th fraction was purified by fractionation using a reverse-phase C18 column and identified by LC-MS and NMR.

[0057] As shown in Table 1, four diterpenoid compounds with PXR activation targets were screened in the preparation examples of this invention, namely compounds 1 to 4. The structures of compounds 1 to 4 were characterized by proton NMR and carbon NMR spectroscopy, and the results are shown in Table 2 and Figure 1. Figure 1 shows the proton NMR and carbon NMR spectra of compounds 1 to 4 in the preparation examples of this invention, (A) compound 1; (B) compound 2; (C) compound 3; (D) compound 4.

[0058] Table 1 Structural formulas of compounds 1-4

[0059]

[0060]

[0061] Table 2. 1H NMR spectral data of compounds 1–4

[0062]

[0063]

[0064] Experimental Example 1

[0065] This example investigates the ability of diterpenoid compounds prepared in the preparation example to activate PXR.

[0066] I. Experimental Methods

[0067] (1) Cytotoxicity studies

[0068] HCT116 colon cancer cells were divided into 1×10 4 Cells were seeded at a density of 1 / mL in 96-well plates and incubated at 37°C with 5% CO2. After adhesion, four compounds (10 μM) prepared according to the preparation examples of this invention were added and incubated for 24 h. Cell viability was measured using the MTT assay.

[0069] (2) Research on the ability to activate PXR

[0070] HCT116 colon cancer cells were divided into 1×10 4 Cells were seeded at a density of 100 ng / well in 96-well culture dishes. After cell adhesion, pCMV6-XL4-hPXR (100 ng / well), PLG-CYP3A4-luc, and TK-luc (10 ng / well) Renilla fluorescent plasmids were transfected using Lipofectamine 2000 reagent. After 24 h, the culture medium was removed, and DMSO (0.1%, v / v), four compounds (10 μM), and the positive control drug pregnenolone-16α-nitrile (PCN, 10 μM) were added. After induction for 48 h, luciferase activity was detected using a luciferase reporter gene assay kit to study the ability of the diterpenoid compounds prepared in this invention to activate PXR.

[0071] II. Experimental Results

[0072] Figure 2 Compounds 1-4, which are examples of preparations of this invention, exhibit relative cytotoxicity against HCT116 colon cancer cells. Figure 3 Compounds 1-4, used in the preparation examples of this invention, induce the activity of CYP3A4 fluorescein. For example... Figure 2As shown, when the concentration of this type of compound was 10 μM, the relative viability of HCT116 cells was close to 100%, indicating that this type of compound has good safety. Figure 3 As shown, after co-transfection with various plasmids, the diterpenoid compound (10 μM) prepared in this invention can significantly induce the activity of CYP3A4-luc luciferase, indicating that this type of compound prepared in this invention has the activity of activating PXR.

[0073] Experimental Example 2

[0074] This example uses compound 4 to explore its efficacy as a natural PXR agonist in improving DSS (dextrose sulfate)-induced ulcerative colitis.

[0075] I. Experimental Methods

[0076] (1) Construction of a mouse model of acute colitis induced by DSS

[0077] Forty SPF-grade 6-8 week old male mice (C57BL / 6J) were acclimatized for one week in an SPF environment with a 12-hour light / 12-hour dark cycle, and adequate water and food were provided. Mice were randomly divided into four groups: a control group (Ctrl group), a model group (DSS group), a positive control group (pregnenolone-16α-nitrile, PCN group), and a treatment group (compound 4 group), with 10 mice in each group. From day 1 to 10, mice in the treatment group were administered 30 mg / kg of the compound by gavage, while the positive control group was administered 10 mg / kg of PCN by gavage. The control and model groups were administered an equal volume (200 μL) of a 0.1% CMC + 3% DMSO mixture by gavage, once daily. From day 4 to 10, concurrently with the drug administration, the treatment group, model group, and positive control group were fed drinking water containing 2.8% DSS for 7 days to induce acute colitis. During the modeling and treatment periods, mice in all groups had free access to water and food. The mice were euthanized after 11 days, and their blood and colon tissue were collected.

[0078] (2) Effect on mouse body weight

[0079] During the experiment, the mice in each group were weighed and their weights recorded daily, and curves were plotted based on weight changes. Mouse feces were also recorded, including instances of diarrhea and bloody stools, and the mice were scored using the Disease Activity Index (DA1).

[0080] (3) Organizational morphology analysis

[0081] Colonic tissue was histologically analyzed using hematoxylin and eosin (H&E) staining. A distal colonic segment (approximately 1 cm) was fixed in formalin (4%, m / V), dehydrated, embedded in paraffin, sectioned, stained with hematoxylin and eosin, dehydrated, and mounted. Images of the H&E-stained sections were then observed using a Nikon Eclipse Ts2R+FL microscope (Nikon Instruments Inc., Tokyo, Japan).

[0082] (4) Measurement of inflammatory factors in colon tissue

[0083] The levels of TNF-α, IL-6, IL-1β, and IL-10 in colon tissue were measured according to the instructions of the ELISA kit.

[0084] (5) Real-time quantitative polymerase chain reaction (qPCR)

[0085] The expression levels of Cypca11 and MDR1a in colon tissue were determined by qPCR. Total RNA was extracted using the Novizan kit, and the assessment of Cypca11 and MDR1a mRNA levels in colon tissue was performed using the TAKARA kit.

[0086] II. Experimental Results

[0087] Figure 4 Compound 4, prepared as an example of this invention, is shown to alleviate DSS-induced colitis. (A) Weight change trend graph; (B) DAI change trend graph; (C) Colon length; (D) Representative colonogram; (E) Colon HE staining image. Results are expressed as mean ± standard deviation, n = 10 for each group. Compared with the control group, ###P < 0.001; compared with the DSS group, ***P < 0.001, **P < 0.05.

[0088] The results showed that, compared with the Ctrl group mice, after DSS-induced ulcerative colitis, the body weight of mice in the model group, treatment group, and positive control group initially increased, followed by the onset of inflammation and a gradual decrease in body weight. Figure 4 A), and the length of the colon is significantly shortened ( Figure 4 Increased C&D) and Disease Activity Index (DAI) scores ( Figure 4 B). The positive control group (PCN group) significantly increased colon length and decreased DAI score in DSS group mice. Furthermore, compound 4 also significantly increased colon length and decreased DAI score in DSS group mice; histopathological evaluation of colon tissue was performed by HE staining, such as... Figure 4As shown in Figure E, the DSS group mice exhibited significant changes in colonic crypt morphology, extensive damage or loss of goblet cells, inflammatory cell infiltration, and severe mucosal injury. In the positive control group (PCN group), the colonic crypt morphology changes were alleviated, goblet cell structure was clear, and inflammatory cell infiltration in the tissue was reduced. Compound 4 alleviated the colonic crypt morphology changes in the DSS group mice, protected goblet cells, and reduced inflammatory cell infiltration. Therefore, Compound 4 of the present invention, as a natural PXR agonist, can effectively improve colonic pathological damage in mice.

[0089] In addition, pro-inflammatory factors IL-6, IL-1β and TNF-α are inflammatory markers closely related to IBD. Figure 5 Compound 4, prepared as an example of this invention, alleviates the inflammatory level of DSS-induced colitis, specifically including: (A) interleukin IL-6; (B) IL-1β; (C) TNF-α; (D) IL-10 levels in colonic tissue. Results are expressed as mean ± standard deviation, with n = 10 for each group. Compared with the control group, ###P < 0.001; compared with the DSS group, ***P < 0.001, **P < 0.05, *P < 0.01.

[0090] like Figure 5 As shown, treatment with compound 4 from the preparation examples of this invention significantly reduced the levels of IL-6, IL-1β, and TNF-α in colonic tissue and increased the level of the anti-inflammatory factor IL-10. Similar effects were observed in the positive control group. In summary, the compounds from the preparation examples of this invention, as natural PXR agonists, can significantly reduce the levels of pro-inflammatory factors and promote the release of anti-inflammatory factors to alleviate intestinal inflammation in DSS-induced ulcerative colitis in mice.

[0091] also, Figure 6 The efficacy of compound 4, prepared in the example of this invention, in activating PXR activity was measured. (A) mRNA level of Cyp3a11; (B) mRNA level of MDR1a. Results are expressed as mean ± standard deviation, n = 10 for each group. Compared with the control group, ###P < 0.001; compared with the DSS group, ***P < 0.001. Figure 6 As shown, mPXR target gene expression analysis revealed decreased levels of Cyp3a11 and MDR1a mRNA in mouse colon tissue. This indicates that compound 4 of the preparation example of this invention, as a natural PXR agonist, can significantly induce the expression of PXR target genes.

[0092] Experimental Example 3

[0093] This example uses compound 4 to investigate its effect as a natural PXR agonist on DSS-induced PXR. - / - The therapeutic effect on ulcerative colitis in mice (mice with PXR gene knockout).

[0094] I. Experimental Design

[0095] 40 SPF-grade 6-8 week old PXR - / - Male rats were acclimatized for one week in an SPF environment with a 12-hour light / 12-hour dark cycle, and with ample water and food. Similar to Experiment 2 above, PXR... - / - Mice were randomly divided into four groups: a control group (Ctrl group), a model group (DSS group), a positive control group (PCN group), and a treatment group (compound 4 group), with 10 mice in each group. From day 1 to 10, mice in the treatment group were administered 30 mg / kg of the compound via gavage, while mice in the positive control group were administered 10 mg / kg of PCN via gavage. The gavage volume for each mouse was 200 μL, administered once daily. From day 4 to 10, concurrently with the drug administration, the treatment group, model group, and positive control group were fed drinking water containing 2.8% DSS for 7 days to induce acute colitis. Mouse weight, diarrhea, and bloody stools were recorded. Mice were sacrificed after 11 days, and blood and colonic tissue were collected to analyze the level of inflammation in the colon and assess the expression of PXR target genes in the colon.

[0096] II. Experimental Results

[0097] Figure 7 Compound 4, used in the preparation examples of this invention, induces PXR in DSS. - / - Therapeutic effect of treatment on acute colitis in mice. (A) Trend chart of body weight; (B) Trend chart of DAI (diastolic blood oxygen saturation); (C) Colon length; (D) Representative colonogram. Results are expressed as mean ± standard deviation, n = 10 per group. Compared with the control group, ###P < 0.001; compared with the DSS group, ns: no significant difference.

[0098] like Figure 7 As shown, when using DSS to induce PXR - / - Following ulcerative colitis in mice, the body weight of mice in the model group, treatment group, and positive control group initially increased and then gradually decreased. Figure 7 A) The length of the colon is significantly shortened ( Figure 7 Increased C&D) and Disease Activity Index (DAI) scores ( Figure 7 B). However, compared with the DSS model group, compound 4 of the present invention and the positive control drug PCN did not alleviate DSS-induced acute enteritis. Therefore, compound 4 of the present invention, as a natural PXR agonist, does not improve PXR. - / - The colonic pathological damage in mice indicates that compound 4 is a PXR target agonist that improves colitis by activating PXR target genes.

[0099] also, Figure 8Compound 4, used as a preparation example of this invention, is related to PXR. - / - Effects of inflammatory factor levels in colitis mice. Levels of (A) IL-6; (B) IL-1β; (C) TNF-α; (D) IL-10 in colon tissue. Compared with the control group, ##P<0.01; compared with the DSS group, ns: no significant difference.

[0100] like Figure 8 As shown, compared with the DSS group, compound 4 of the preparation example of the present invention and the positive control drug PCN treatment did not significantly reduce PXR. - / - The levels of inflammatory factors IL-6, IL-1β, and TNF-α in mouse colon tissue were increased, as was the level of the anti-inflammatory factor IL-10.

[0101] In summary, this invention screened natural agonists from *Hedyotis diffusa* that activate PXR targets. These agonists bind to PXR ligand domains, thereby activating the PXR target and playing a vital role in regulating intestinal homeostasis and reducing inflammation, thus contributing to the treatment of ulcerative colitis. The PXR agonists prepared in this invention effectively activate PXR target genes both in vitro and in vivo, effectively alleviating DSS-induced ulcerative colitis through PXR target gene activation.

[0102] This invention utilizes diterpenoid compounds extracted from *Hedyotis diffusa* as PXR agonists, which can regulate inflammation by activating PXR receptors. Animal experiments have shown that these compounds have high affinity for PXR targets and can improve DSS-induced ulcerative colitis by delaying weight loss in mice, slowing colon shortening, improving colonic DAI scores, downregulating pro-inflammatory factors, and activating PXR target genes.

[0103] The diterpenoid compounds of this invention have high affinity for PXR targets and significant anti-inflammatory effects. They can significantly treat inflammatory bowel disease by activating intestinal PXR targets and regulating the level of inflammatory factors. Furthermore, as natural extracts, they have the advantages of significant efficacy and low toxicity, and have wide applications in the preparation of PXR agonists or drugs for treating inflammatory bowel disease.

Claims

1. The use of a diterpenoid compound in the preparation of a medicament for treating inflammatory bowel disease, characterized in that, The inflammatory bowel disease mentioned is ulcerative colitis; The diterpenoid compound serves as a PXR agonist; The diterpenoid compound is selected from at least one of the compounds shown in formulas (1) to (4): （1）； （2）； （3）； （4）。 2. The application according to claim 1, characterized in that, The diterpenoid compound is prepared by a method comprising the following steps: extracting *Hedyotis diffusa* by percolation to obtain an extract, and then extracting, separating and purifying the extract to obtain the diterpenoid compound; The percolation method uses an alcohol solvent as the extraction solvent; the extraction solvent is an ester solvent; the separation and purification are performed by sequentially eluting with a silica gel column, a dextran gel column, and a reversed-phase chromatography column; the eluent used for elution with the silica gel column is a mixed solution of ether solvent and ester solvent; the eluent used for elution with the dextran gel column is an alcohol solvent.

3. The application according to claim 2, characterized in that, The percolation method uses an extraction solvent with a dosage ratio of (10~15) L: 1 kg for *Hedyotis diffusa*.

Images