CN113234052A

CN113234052A - Extracellular regulatory protein kinase inhibitor and preparation method and application thereof

Info

Publication number: CN113234052A
Application number: CN202110423088.8A
Authority: CN
Inventors: 郑多; 江承尧; 朱礼志; 张敏; 黄均荣; 曾娟
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2021-04-20
Filing date: 2021-04-20
Publication date: 2021-08-10

Abstract

The application provides an ERK1/2 inhibitor, wherein the structural formula of the ERK1/2 inhibitor is shown in a formula I, the structural formula utilizes the unsaturated double bond of the D ring on the structure to react with the 183/166 th cysteine at the position of a pocket of an ERK1/2 kinase region to generate a stable and irreversible covalent bond, meanwhile, 3-5 hydrogen bond binding sites are formed, the binding capacity with the target protein ERK1/2 action pocket is improved, and stabilizes the covalent small molecule-target protein binding product, thereby inhibiting the activation of the ERK1/2 protein, and further, the expression of the downstream target genes AREG and EREG of the ERK is reduced, the activation of the upstream EGFR and the EGFR pathway are feedback-inhibited, and finally the growth of the cell line activated by the EGFR/MEK/ERK pathway and the tumor is effectively inhibited, so that the cancer inhibition effect is achieved, and the method has the potential of being applied to the preparation of anti-cancer drugs.

Description

Extracellular regulatory protein kinase inhibitor and preparation method and application thereof

Technical Field

The application belongs to the technical field of inhibitors, and particularly relates to an extracellular regulated protein kinase inhibitor, and a preparation method and application thereof.

Background

The Mitogen Activated Protein Kinase (MAPK) pathway is one of common intersection pathways for regulating and controlling signal transduction of cell proliferation, stress, inflammation, differentiation, function synchronization, transformation, apoptosis and the like, and extracellular signals are transmitted to cells through a signal network consisting of receptors, G protein/small G protein, protein kinase, transcription factors and the like to participate in various biological behaviors. In different cells, MAPK pathways can receive different growth stimuli and stress stimuli, and generate a plurality of effects through specific signal pathways limited by specific cytoskeletons. The extracellular regulatory protein kinase (ERK1/2) is widely expressed protein serine/threonine kinase, is also a key member of MAPK signal channel, can be stimulated by various growth factors, ion rays, hydrogen peroxide and the like to be activated, enters cell nucleus, acts on transcription factors such as E1k-1, c-myc, c-fos, c-jun, ATF, NF-kB, AP-1 and the like, promotes the transcription and expression of target genes, and regulates the proliferation and differentiation of cells.

When cancer or other diseases occur in the organism, the upstream component of MAPK pathway is activated and mutated, and the activity of ERK1/2 is up-regulated correspondingly, thereby leading to the formation of various cancers. A large number of clinical studies show that inhibition of the MAPK pathway can inhibit the growth of part of cancer cell lines, thereby achieving the purpose of controlling diseases.

Most of the currently developed ERK1/2 inhibitors are non-covalent binding compounds, and in the using process, the ERK1/2 inhibitors are not tightly bound with the Erk1/2 kinase regional pocket, so that the action effect is unstable, and meanwhile, most of the ERK1/2 inhibitors are artificially synthesized, have high toxicity and poor safety and are not beneficial to clinical wide use.

Disclosure of Invention

The application aims to provide an extracellular regulatory protein kinase (ERK1/2) inhibitor, and a preparation method and application thereof, and aims to solve the problems that in the prior art, the ERK1/2 inhibitor is not tightly combined with an ERK1/2 kinase region pocket, the use effect is unstable and the safety is poor due to easy off-target.

In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:

in a first aspect, the application provides an ERK1/2 inhibitor, wherein the ERK1/2 inhibitor is Laxiflorin B and derivatives thereof, the ERK1/2 inhibitor has a structural general formula shown in formula I,

formula I;

wherein R1 is selected from any one of H, alkyl ester, amino acid ester, aryl ester, heteroaryl ester, substituted aryl ester and substituted heteroaryl ester.

In a second aspect, the present application provides a method for preparing an ERK1/2 inhibitor, comprising the steps of:

obtaining eriocalyx rabdosia herb medicinal material powder, performing reflux extraction treatment on the eriocalyx rabdosia herb medicinal material powder by adopting an alcohol solution, and then sequentially performing separation treatment, recrystallization and concentration to obtain eriocalyxin B;

mixing the eriocalyxin B and an organic solvent, heating and refluxing, and purifying to obtain a reflux product;

and mixing the reflux product with a reducing agent for reduction reaction, and then purifying to obtain the ERK1/2 inhibitor.

In a third aspect, the application provides an application of an ERK1/2 inhibitor prepared by a preparation method of an ERK1/2 inhibitor or an ERK1/2 inhibitor in preparation of an anti-cancer drug.

The ERK1/2 inhibitor provided by the first aspect of the application is shown in formula I, wherein the structural formula of the ERK1/2 inhibitor is shown in formula I, the structural formula utilizes a D-ring unsaturated double bond to react with the 183/166 th cysteine at the position of a pocket of an ERK1/2 kinase region to generate a stable and irreversible covalent bond through Michael reaction, and meanwhile, 3-5 hydrogen bonds are formed with amino acid residues around the pocket of the ERK1/2 kinase region. Covalent bonds, hydrogen bonds, and matched hydrophobic interactions and molecular shapes are beneficial to improving the binding capacity of the compound with the target protein ERK1/2 action pocket and stabilizing covalent small molecule-target protein binding products, thereby inhibiting the activation of ERK1/2 protein.

In the preparation method of the ERK1/2 inhibitor provided by the second aspect of the application, the eriocalyxin B is extracted from natural plants, and then the eriocalyxin B is used as a raw material, and the eriocalyxin B is converted into the ERK1/2 inhibitor by a semisynthesis method, so that the raw material of the preparation method is easy to obtain, the cost is low, the operation is simple, and on one hand, compared with other artificially synthesized chemical inhibitors, the toxicity is lower and the preparation method is safer; on the other hand, compared with the method for directly extracting Laxiflorin B from medicinal plants, the method can greatly improve the yield of Laxiflorin B and is easy to realize industrial production and application.

The third aspect of the application provides that the ERK1/2 inhibitor can improve the binding capacity with the action pocket of the target protein ERK1/2 and stabilize the covalent small molecule-target protein binding product, thereby inhibiting the activation of the ERK1/2 protein, effectively inhibiting the growth of cell lines and tumors activated by Mitogen Activated Protein Kinase (MAPK) pathways, further achieving the cancer inhibition effect, and being applicable to the preparation of anti-cancer drugs.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a flow chart for the preparation of the ERK1/2 inhibitor Laxiflorin B of structural formula I-1 as provided in the examples herein.

FIG. 2 is a graph showing the cell survival inhibitory effect of the ERK1/2 inhibitor Laxiflorin B on different cells, provided in the examples of the present application.

FIG. 3 is a graph showing the results of inducing apoptosis of different cells by Laxiflorin B, an ERK1/2 inhibitor, provided in the examples of the present application.

Fig. 4 is a graph showing the inhibitory effect of Laxiflorin B on EGFR signaling pathway provided in the examples of the present application.

Fig. 5 is a graph of an analysis of the binding of Laxiflorin B to EGFR pathway members provided in the examples of the present application.

FIG. 6 is a graph of mass spectrometry of Laxiflorin B binding to ERK1 provided in the examples of the present application.

Fig. 7 is a structural and activity analysis diagram of Laxiflorin a, a structural analog of Laxiflorin B, provided in the embodiments of the present application.

FIG. 8 is a chemical structural diagram of each Laxiflorin B analog provided in examples of the present application.

FIG. 9 is a graph of the results of a Laxiflorin B analog pull-down experiment provided in the examples of the present application.

FIG. 10 shows the molecular docking results of Laxiflorin B with ERK1 provided in the examples of the present application.

FIG. 11 shows the molecular docking results of Laxiflorin B with ERK2 provided in the examples of the present application.

FIG. 12 is a graph showing the experimental procedures for tumor-bearing mice and the results of inhibition of tumor growth by Laxiflorin B, provided in the examples of the present application.

FIG. 13 is a graph showing the tumor size and tumor size analysis after three weeks of administration of tumor-bearing mice provided in the examples of the present application.

FIG. 14 is a graph of body weight of tumor-bearing mice versus relative heart, kidney and liver weights three weeks after administration, as provided in the examples herein.

Fig. 15 is a graph showing the structures of Laxiflorin B derivatives and the effect of inhibiting cell viability thereof, provided in the examples of the present application.

Fig. 16 is a graph showing the analysis of the effect of Laxiflorin B (AREG, EREG are used as the analysis indices) provided in the examples of the present application.

FIG. 17 is a graph showing the expression analysis of Ampheirulin (AREG gene product) and Epirerulin (EREG gene product) proteins in tumor-bearing mouse tumors, which is provided in the examples of the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

The first aspect of the embodiment of the application provides an ERK1/2 inhibitor, wherein the ERK1/2 inhibitor is Laxiflorin B and derivatives thereof, the structural general formula of the ERK1/2 inhibitor is shown in formula I,

The ERK1/2 inhibitor provided by the first aspect of the application is shown in formula I, wherein the structural formula of the ERK1/2 inhibitor is shown in formula I, the structural formula utilizes D-ring unsaturated double bonds to generate stable and irreversible covalent bonds with the 183/166 th cysteine at the position of a pocket of an ERK1/2 kinase region through Michael reaction, and simultaneously, 3-5 hydrogen bond binding sites and matched hydrophobic effects and molecular shapes are formed with amino acid residues around the pocket of the ERK1/2 kinase region, which are beneficial to improving the binding capacity of the structural molecule and a target protein ERK1/2 action pocket and stabilizing covalent small molecule-target protein binding products, thereby inhibiting the activation of ERK1/2 protein, effectively inhibiting signal transduction in tumors activated by Mitogen Activated Protein Kinase (MAPK) pathways and further effectively inhibiting the growth of the tumors, achieves the effect of inhibiting cancer and has the potential of being applied to the preparation of anti-cancer drugs.

In particular, ERK1/2 inhibitors

In the general structural formula I, stable and irreversible covalent bonds can be generated by Michael reaction with the 183/166 th cysteine at the position of a pocket of an ERK1/2 kinase region, and meanwhile, 3-5 hydrogen bond binding sites and matched hydrophobic effect and molecular shape are formed with amino acid residues around the pocket of the ERK1/2 kinase region, so that the docking effect with ERK1/2 kinase can be further enhanced.

In some embodiments, R in formula I¹Selected from H, when the structure of the ERK1/2 inhibitor is shown as a formula I-1,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-2,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-3,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-4,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-5,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-6,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-7,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-8,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-9,

in some embodiments, R in formula I¹Is selected from

The structure of the ERK1/2 inhibitor is shown as formula I-10,

wherein, the sixth carbon of the formula I-1 is modified on the basis of the formula I-1 by the formula I-2 to the formula I-10, and the sensitivity of tumor cells to drugs can be increased by adopting the substituent groups for modification, the poisoning capability of the drugs to the tumor cells can be increased, and the effect on tumors is improved.

In some embodiments, the ERK1/2 inhibitor further comprises at least one of a pharmaceutically acceptable adjuvant, and prodrug.

In some embodiments, the IC50 of the ERK1/2 inhibitor of structural formula I-1 is about 1 μ M for three non-small cell lung cancer cell lines, such as PC9, HCC827 and H1650, so that the LAXIflorin B inhibitor of the ERK1/2 of structural formula I-1 can generate better inhibition effect on the non-small cell lung cancer cell lines only with lower concentration.

In some embodiments, the inhibitor Laxiflorin B of ERK1/2 with structural formula I-1 affects many physiological reactions in cells, including cell cycle, metabolism, etc., and also affects many signal paths in cells, wherein the most significant effects are ErbB and MAPK paths.

In some embodiments, the ERK1/2 inhibitor Laxiflorin B of structural formula I-1 is capable of forming a complex bound in an "inner" configuration or a complex bound in an "out" configuration with ERK1 and ERK2, respectively, using molecular docking assays, wherein the covalent bond with amino acids 183 of ERK1 and 166 of ERK2 is well bound within the binding pocket of ERK1 and ERK 2. The "inner" configuration has no hydrogen bonds with ERK1, but the O5 oxygen atom of the "inner" configuration forms a hydrogen bond with the glutamine side chain at position 105 of ERK 2. The O7 oxygen atom in the "out" configuration forms a hydrogen bond with the asparagine side chain at position 171 of ERK1, but the "out" configuration has no hydrogen bond with ERK 2. Further, the binding sites of Laxiflorin B on the surfaces of ERK1 and ERK2 are found to be consistent through kinetic simulation. The binding pattern of the "out" configuration is consistent whether within the binding pocket of ERK1 or ERK2, with the O7 oxygen atom of Laxiflorin B forming stable hydrogen bonds with the 128-position aspartic acid side chain of ERK1 or the 111-position aspartic acid side chain of ERK 2. While the "inner" configuration presents a different binding pattern in 3 within the binding pocket of ERK1, the binding pattern in ERK2 is consistent with the "out" configuration. The dynamic simulation finds that phosphorylation modifications of amino acids 185 and 187 of ERK2 have certain influence on the binding mode of Laxiflorin B. The binding pattern of Laxiflorin B in 185 and 187 phosphorylation modified ERK2 was consistent, but different from that before phosphorylation modification. After phosphorylation modification, the hydrogen bond between O7 oxygen atom of Laxiflorin B and 111 th aspartic acid side chain is broken, but O5 oxygen atom and 35 th alanine of ERK2 form hydrogen bond interaction.

In a second aspect, the embodiments of the present application provide a method for preparing an ERK1/2 inhibitor, comprising the following steps:

s01, obtaining medicinal herb powder of rabdosia eriocalyx, performing reflux extraction treatment on the medicinal herb powder of rabdosia eriocalyx by using an alcohol solution, and then sequentially performing separation treatment, recrystallization and concentration to obtain eriocalyxin B;

s02, mixing eriocalyxin B and an organic solvent, heating and refluxing, and purifying to obtain a reflux product;

and S03, mixing the reflux product with a reducing agent to perform a reduction reaction, and then performing purification treatment to obtain an ERK1/2 inhibitor.

In the preparation method of the ERK1/2 inhibitor provided by the second aspect of the application, the eriocalyxin B is extracted from natural plants, and then the eriocalyxin B is used as a raw material, and the eriocalyxin B is converted into the ERK1/2 inhibitor by a semisynthesis method, so that the raw material of the preparation method is easy to obtain, the cost is low, the operation is simple, and on one hand, compared with other artificially synthesized chemical inhibitors, the preparation method is lower in animal toxicity and safer; on the other hand, compared with the method for directly extracting Laxiflorin B from medicinal plants, the method can greatly improve the yield of Laxiflorin B and is easy to realize industrial production and application.

In step S01, the step of obtaining rabdosia pilifera medicinal material powder includes: the method comprises the steps of obtaining a rabdosia macalyx medicinal material, carrying out air drying treatment on the rabdosia macalyx medicinal material, and then crushing the rabdosia macalyx medicinal material into rabdosia macalyx medicinal material powder with the mesh number of 10-60 meshes.

Further, the step of performing reflux extraction treatment on the rabdosia majorana medicinal material powder by adopting an alcohol solution comprises the following steps: providing a methanol water solution with the volume percentage concentration of 80-85%, and carrying out reflux extraction treatment on rabdosia maackii medicinal material powder for 2 hours; and then decompressing and recovering the methanol to concentrate the extract solvent until the volume percentage concentration of the methanol is 40-45 percent, thereby obtaining the reflux extraction product.

Further, the separation treatment is carried out by any one of a chromatographic separation treatment, a gel column separation treatment, a recrystallization separation treatment and a preparative liquid phase separation treatment.

In some embodiments, the separation treatment, recrystallization and concentration sequentially comprise the following steps:

s011, standing and crystallizing the reflux extraction product until a large amount of white solid is separated out, and filtering to obtain a filtrate;

s012, purifying the filtrate by methods such as chromatographic separation, gel column decoloration, recrystallization, preparation of liquid phase separation and the like in sequence to obtain a crude filter cake extract;

s013, heating and dissolving the crude extract of the filter cake through methanol, decoloring through activated carbon, filtering, collecting filtrate, and recrystallizing and concentrating to obtain the eriocalyxin B.

The rabdosia eriocalyx medicinal material is successfully separated from 2Kg of dried branches and 50g of dried leaves by adopting the separation process to obtain more than 500mg of eriocalyxin B.

In step S02, eriocalyxin b and an organic solvent are mixed, heated and refluxed, and then purified to obtain a refluxed product.

In some embodiments, the step of mixing eriocalyxin b with an organic solvent for a heat reflux treatment comprises: dissolving eriocalyxin B in dichloromethane, heating to a reflux state, adding 1.5 equivalents of dess-Martin reagent, and continuously refluxing for 2-2.5 hours.

Further, carrying out purification treatment, wherein the purification treatment adopts column chromatography separation for purification treatment.

In some embodiments, a method of purification treatment comprises:

s021, providing a chromatography detection raw material, completely reacting the chromatography detection raw material with a product obtained by heating reflux treatment, and cooling to room temperature to obtain a first mixed solution;

s022, adding saturated sodium bicarbonate water solution and saturated sodium thiosulfate water solution into the first mixed solution to quench reaction, extracting for 3 times by using ethyl acetate, collecting organic phases, combining the organic phases, washing by using saturated saline solution, and drying by using anhydrous sodium sulfate to obtain a second mixture;

s023, performing decompression spin drying on the second mixture to obtain a second mixture, wherein the volume ratio of the second mixture is 3: 1 petroleum ether-ethyl acetate mixture is subjected to rapid column chromatography separation to obtain a reflux product, namely an aldehyde intermediate.

In step S03, the reflux product is mixed with a reducing agent for reduction reaction, and then purification treatment is carried out to obtain the ERK1/2 inhibitor.

In some embodiments, the step of mixing the reflux product with a reducing agent to perform a reduction reaction comprises: dissolving the reflux product in a solvent with the volume ratio of (10-12): 1 to obtain a mixed solution; and cooling the mixed solution to 0 ℃, mixing with sodium borohydride, and carrying out reduction reaction for 30-40 minutes.

Further, carrying out purification treatment to obtain the ERK1/2 inhibitor, wherein the purification treatment adopts column chromatography separation for purification treatment.

In some embodiments, a method of purification treatment comprises:

s031, providing chromatography detection raw materials, reacting the chromatography detection raw materials with a product obtained by a reduction reaction completely, and cooling to room temperature to obtain a second mixed solution;

s032, adding a saturated sodium bicarbonate aqueous solution into the second mixed solution to quench reaction, extracting with ethyl acetate for 3 times, collecting organic phases, combining the organic phases, washing with saturated saline solution, and drying with anhydrous sodium sulfate to obtain a third mixture;

and S033, performing reduced pressure spin drying on the third mixture to obtain a solvent, wherein the volume ratio is 3: 1 petroleum ether-ethyl acetate mixture is subjected to flash column chromatography separation to obtain the ERK1/2 inhibitor.

Wherein the obtained ERK1/2 inhibitor is ERK1/2 inhibitor Laxiflorin B with a structural formula I-1.

In some embodiments, to obtain an ERK1/2 inhibitor of structural formula I-2 through I-9, the method of preparation further comprises:

G01. dissolving an ERK1/2 inhibitor Laxiflorin B of a structural formula I-1 in dichloromethane by using a solvent of 1:1, adding an acid compound of a corresponding substituent group in proportion, and cooling to 0 ℃;

G02. adding 1-ethyl- (3-dimethylaminopropyl) carbonyldiimine hydrochloride (EDC.HCl) and 4-Dimethylaminopyridine (DMAP), slowly heating to room temperature, and reacting for 3 hours to obtain a crude reaction product;

G03. and (3) completely reacting the reaction crude product with chromatographic detection raw materials, adding saturated sodium bicarbonate aqueous solution to quench the reaction, extracting for 3 times by using ethyl acetate, combining organic phases, washing by using saturated saline solution, drying by using anhydrous sodium sulfate, and then performing decompression spin-drying on the solvent by adopting a volume ratio of 2:1, mixing the petroleum ether with ethyl acetate, and performing rapid column chromatography separation to obtain a corresponding product.

The third aspect of the embodiment of the application provides application of the ERK1/2 inhibitor or the ERK1/2 inhibitor prepared by the preparation method of the ERK1/2 inhibitor in preparing an anti-cancer drug.

The third aspect of the application provides an ERK1/2 inhibitor which can improve the binding capacity with the action pocket of a target protein ERK1/2 and stabilize a covalent small molecule-target protein binding product, so that the activity of the ERK1/2 protein is inhibited, the growth of part of cancer cell lines is effectively inhibited by inhibiting a signal channel, the purpose of controlling diseases is further achieved, and the ERK1/2 inhibitor can be applied to the preparation of anti-cancer drugs.

The following description will be given with reference to specific examples.

Example 1

Preparation of ERK1/2 inhibitor Laxiflorin B with structural formula I-1

The ERK1/2 inhibitor Laxiflorin B of structural formula I-1 is as follows:

the preparation method is shown in figure 1, and the detailed flow is as follows:

(1) obtaining eriocalyx rabdosia herb medicinal material powder, performing reflux extraction treatment on the eriocalyx rabdosia herb medicinal material powder by adopting an alcohol solution, and then sequentially performing separation treatment, recrystallization and concentration to obtain eriocalyxin B:

the detailed steps are as follows: purchasing a fresh picked rabdosia pilifera medicinal material, separating branches and leaves, naturally drying in the air, crushing into 10-60 meshes, respectively carrying out reflux extraction on the branch and leaf powder for 3 times by 2 hours and 80% methanol water, recovering methanol under reduced pressure, concentrating an extract solvent until the methanol is about 40%, and transferring, standing and crystallizing. Separating out a large amount of white solid, filtering, and purifying the filtrate by chromatographic separation, gel column decolorization, recrystallization, preparative liquid phase separation and other methods; heating and dissolving the crude extract of the filter cake by methanol, decoloring by active carbon, filtering, collecting filtrate, and recrystallizing and purifying.

(2) Mixing eriocalyxin B and an organic solvent, heating and refluxing, and purifying to obtain a reflux product;

the detailed steps are as follows: dissolving eriocalyxin B as an initial raw material in dichloromethane, adding a dess-Martin reagent (DMP), and heating and refluxing for 2 h;

further, the product of heating reflux and chromatographic detection raw materials react completely, the reaction is cooled to room temperature, saturated sodium bicarbonate water solution and saturated sodium thiosulfate water solution are added to quench the reaction, ethyl acetate is used for extraction for 3 times, organic phases are combined and washed by saturated saline solution, after being dried by anhydrous sodium sulfate, the solvent is dried by decompression and rotation, and the reflux product, namely the aldehyde intermediate, is obtained by fast column chromatographic separation (petroleum ether: ethyl acetate).

(3) And mixing the reflux product with a reducing agent for reduction reaction, and then purifying to obtain the ERK1/2 inhibitor.

The detailed method comprises the following steps: the reflux product (i.e. aldehyde intermediate) was dissolved in tetrahydrofuran: in a solution of acetic acid (10: 1), cooling to 0 ℃ in an ice bath, adding sodium borohydride, and carrying out reduction reaction for 30 min;

further, the product obtained by the reduction reaction completely reacts with the chromatographic detection raw material, saturated sodium bicarbonate aqueous solution is added to quench the reaction, ethyl acetate is used for extraction for 3 times, organic phases are combined and washed by saturated saline solution, after drying by anhydrous sodium sulfate, the solvent is dried by spinning under reduced pressure, and Laxiflorin B is obtained by fast column chromatography separation (petroleum ether: ethyl acetate).

And (4) analyzing results:

according to the preparation method of example 1, the eriocalyxin B of 500mg or more is successfully separated from the dried branches of 2Kg of the rabdosia eriocalyx medicinal material and 50g of the dried leaves of the rabdosia eriocalyx medicinal material. And EB was converted to Laxiflorin B by a semisynthetic method, resulting in a yield of Laxiflorin B of 70%.

Example 2

Analysis of tumor-inhibiting Effect of ERK1/2 inhibitor Laxiflorin B of structural formula I-1

Test one test procedure:

(1) three non-small cell lung cancer cell lines, PC9, HCC827 and H1650, were seeded at 3000-.

(2) Adding Laxiflorin B with different concentrations after the cells adhere to the wall, adding a CCK-8 coloring reagent at different time points (24 hours, 48 hours and 72 hours), placing the mixture in an incubator at 37 ℃ and reacting for 2 hours.

(3) Absorbance readings at 450nm were measured with a microplate reader and inhibition plots were made in excel.

Analysis of test results:

example 2 test one the test results are shown in fig. 2, fig. 2(a) is a graph of the inhibitory effect of ERK1/2 inhibitor Laxiflorin B on PC9 cells, fig. 2(B) is a graph of the inhibitory effect of ERK1/2 inhibitor Laxiflorin B on HCC827 cells, and fig. 2(C) is a graph of the inhibitory effect of ERK1/2 inhibitor Laxiflorin B on H1650 cells; in the figure, the X-axis is the concentration of Laxiflorin B (μ M) and the Y-axis is the different cell viability (%). When the concentration of the drug inhibits 50% of cell viability, the drug is called as a 'half inhibitory dose' (IC50) of the drug to cells, and the IC50 of three cells used in the experiment is about 1 mu M, which shows that Laxiflorin B only needs lower concentration to generate better inhibition effect on non-small cell lung cancer cell lines.

Test II test procedure:

(1) at 5X10 in 96-well plates⁵The density of cells/well was seeded into three non-small cell lung cancer cell lines, PC9, HCC827 and H1650, respectively, and 3 replicates of each group treated with different Laxiflorin B concentrations (0, 1,2, 4. mu.M) were used for subsequent statistical analysis.

(2) After the cells are attached to the wall, Laxiflorin B with different concentrations is added for treatment for 48 hours.

(3) After trypsinizing the cells, they were stained with Propidium Iodide (PI) and annexin V-FITC reagent set away from light for 1 hour at room temperature, washed with PBS buffer and centrifuged, and repeated 3 times.

(4) Analyzing the apoptosis condition of the line by a flow cytometer, and quantifying and counting.

Analysis of the results of test two:

the test results of the second test in example 2 are shown in FIG. 3, in which FIG. 3(A) is a graph showing the effect of the ERK1/2 inhibitor Laxiflorin B on PC9 cells, FIG. 3(B) is a graph showing the effect of the ERK1/2 inhibitor Laxiflorin B on HCC827 cells, and FIG. 3(C) is a graph showing the effect of the ERK1/2 inhibitor Laxiflorin B on H1650 cells. Comparing the percentage of the cells in the first quadrant in each graph, wherein the first quadrant represents the cells which are simultaneously infected with PI and annexin V and belong to late apoptosis cells, and the comparison result shows that the percentage of cells which can induce three types of apoptosis is higher along with the increase of the concentration of Laxiflorin B, which indicates that Laxiflorin B has the cancer inhibition function.

Example 3

Analysis of the Signal pathway for the Down-Regulation of the ERK1/2 inhibitor Laxiflorin B of structural formula I-1

The test process comprises the following steps:

(1) PC9, HCC827, H1650 cells were treated with 0,1,2, 4. mu.M Laxiflorin B for 24 hours.

(2) Total protein was harvested and quantified, and expression levels of the relevant signaling proteins and their phosphorylation in the EGFR pathway were analyzed by Western Blot.

And (4) analyzing results:

the test results of example 3 are shown in fig. 4, and it is demonstrated that, by Western Blot analysis, the phosphorylation level of EGFR pathway-associated protein after treatment with Laxiflorin B decreases with increasing compound dose, indicating that Laxiflorin B can effectively inhibit EGFR-associated signaling pathway.

Example 4

Protein pull-down experiments and mass spectrometry are utilized to prove that the target protein and the binding amino acid of Laxiflorin B

Test one test procedure:

(1) the biotin-labeled Laxiflorin B was bound to streptavidin magnetic beads for use.

(2) Total protein from PC9 cells was extracted and 2mg of total protein was incubated with 10. mu.L of magnetic beads for 16 hours at 4 ℃.

(3) The magnetic beads are adsorbed by a magnetic frame, washed for 3 times by PBS buffer solution, and then the Laxiflorin B-bound protein is detected by a Western Blot method by using specific antibodies such as EGFR, RAS, RAF, MEK, ERK, RSK, AKT and the like.

Analysis of test results:

as shown in FIG. 5, ERK1/2 was more significantly bound to Laxiflorin B, and either the other protein was weaker or no signal, indicating that ERK1/2 may be the target protein of Laxiflorin B.

Test II test procedure:

(1) the ERK1-Flag recombinant protein is over-expressed in HEK293T cells, and the total protein of the cells is extracted after 48 hours.

(2) After incubating Laxiflorin B with the total protein at 4 ℃ for 16 hours, ERK1-Flag protein was enriched with magnetic beads coupled with anti-Flag antibody and washed 3 times with PBS buffer.

(3) A reaction solution containing sodium deoxycholate SDC (sodium deoxycholate), Tris (2-carboxyethyl) phosphine Hydrochloride TCEP (Tris- (2-carboxyethyl) phosphine, Hydrochoride) and chloroacetamide CAA (Chloroacetamide) was added to the magnetic beads to perform one-step reduction, alkylation and elution. The steps are repeated for 2 times, the eluent is merged, and pancreatin is added for enzymolysis overnight after water is added for dilution. Desalting the peptide fragment solution after enzymolysis through a desalting column. After being dried by a centrifugal concentrator, the product is frozen at the temperature of minus 20 ℃ and waits for being detected on a machine.

(4) Mass spectrometry was performed using a TripleTOF 5600+ LC-MS system from SCIEX. The samples were separated by a liquid phase eksiogen microLC 415 system with microliter flow rate. The peptide fragment sample was dissolved in loading buffer, aspirated by an autosampler, bound to a C18 capture column (5 μm,

300 μm × 5mm) and then eluted to an analytical column (3 μm,

300 μm × 15 mm). An analytical gradient was established using two mobile phases (mobile phase A: 3% DMSO, 0.1% formic acid, 97% H2O and mobile phase B: 3% DMSO, 0.1% formic acid, 97% ACN). The flow rate of the liquid phase was set to 5. mu.L/min. For mass spectrum DDA mode analysis, each scanning cycle comprises one MS full scan (scan range 350-1500 m/z, acquisition time 250MS), and then 40 MS/MS scans (scan range 100-1500 m/z, acquisition time 50 MS). The signal of the peptide fragment ions with the signal of more than 120cps (+ 2- +5) triggers MS/MS scanning. The exclusion time for MS/MS duplicate acquisitions was set at 18 s.

(5) The mass spectra data generated by TripleTOF 5600+ were retrieved by ProteinPilot (V4.5) using the database retrieval algorithm, Paragon. The database used for the search was the proteome reference database of Human in UniProt. The search parameters are as follows: the Sample Type selects Identification; selecting Iodoacetamide from Cys Alkylation; digestion selects Trypsin; the Search efficiency is set to Rapid ID. And screening the retrieval result by taking Ununsed not less than 1.3 as a standard, deleting the retrieved items and the pollution protein in the anti-library, and using the remaining identification information for subsequent analysis. Based on the number of each protein spectrum, proteins with significant differences in different samples were screened. To facilitate statistical analysis and reduce false positive results from low abundance protein identification, the data with a spectrogram number of 0 will be artificially filled with 1. The ratio of the number of spectra (KRAS/HA ratio) and the mean number of spectra (MeansP) were calculated for each protein in different samples, where x is log2(KRAS/HA ratio) and y is log2 (MeansP).

Analysis of the results of test two:

as shown in FIG. 6A, an increase in the molecular weight of Laxiflorin B (344.4Da) was detected in the peptide fragment of ERK1(182-189) with a covalent binding site at cysteine at position 183.

As shown in FIG. 6B, an increase in the molecular weight of Laxiflorin B (344.4Da) was detected in the peptide fragment of ERK1(166-181), with the covalent binding site at cysteine at position 178.

Example 5

Laxiflorin A (lacking the covalent activity on the Laxiflorin B D ring) which is a structural analogue of Laxiflorin B does not have biological activity

And (3) test analysis:

(1) and (3) detecting the activity of the cells:

firstly, non-small cell lung cancer cell lines such as PC9 and A549 are respectively planted in a 96-well plate at the density of 3000-.

② adding Laxiflorin B with different concentrations after the cells adhere to the wall, adding CCK-8 coloring reagent at the time point of 48 hours, placing in an incubator at 37 ℃ and reacting for 2 hours.

Thirdly, reading the light absorption value of 450nm by using a microplate reader, and drawing an inhibition curve graph by using excel.

(2) And (3) signal path detection:

put 5x10 seeds in 6 cm culture dish⁵A549 cells or PC9 cells, which were treated with different Laxiflorin A concentrations (0,50, 100. mu.M) for 48 hours after they reached a full 7 min.

② Western Blot is used for detecting the expression of proteins pERK1/2, ERK1/2, pAKT, AKT and the like related to cell proliferation and survival pathway after collecting total protein.

And (4) analyzing results:

as a result, as shown in fig. 7A, Laxiflorin a and Laxiflorin B have only one OH group different in structure (shown by a dotted frame), and this OH group is located at ring D of Laxiflorin B, and thus, the anticancer activity of Laxiflorin B can be inhibited.

The results of cell activity assays are shown in fig. 7B and 7C, fig. 7B is an analysis chart of the effect of Laxiflorin a on cell a549, and fig. 7C is an analysis chart of the effect of Laxiflorin a on cell PC9, where the X axis is Laxiflorin a concentration (μ M) and the Y axis is cell viability (%), and it can be seen that Laxiflorin a has no inhibitory effect on the proliferation of cell a549 and cell PC 9.

The results of the signal pathway detection are shown in fig. 7D and 7E, fig. 7D is an analysis chart of the results of the action of Laxiflorin a on cell PC9, and fig. 7E is an analysis chart of the results of the action of Laxiflorin a on cell a549, and there was no inhibitory effect on the signal pathway related to cell proliferation and survival.

Example 6

The cancer suppressor activity of Laxiflorin B is an assay for binding of 183 nd (Cys) cysteine in ATP pocket in ERK1 kinase domain via the structural D-ring

The test process comprises the following steps:

(1) synthesis of biotin-labeled Laxiflorin B analogues:

add Des-Martin reagent (852mg,2mmol) to a solution of Eriocalyxin B (344mg,1mmol) in DCM (10mL) at RT. Slowly heating to 40 ℃, stirring for 30min, cooling to room temperature, detecting by TLC that the reaction raw materials completely disappear, and adding saturated sodium thiosulfate solution (2ml) to quench the reaction.

② adding saturated sodium chloride solution (10mL), extracting with ethyl acetate (10mL multiplied by 3), merging organic phases and concentrating. Column chromatography (PE/EA ═ 1:1) afforded the aldehyde compound (257mg,0.75mmol) as a white solid.

Dissolving the aldehyde compound in 2mL of THF solvent, adding 0.2mL of acetic acid, cooling to 0 ℃, then adding sodium borohydride solid (30mg, 0.75mmol), slowly returning to room temperature, reacting for 1 hour, detecting by TLC that the reaction raw material completely disappears, adding saturated sodium bicarbonate aqueous solution to quench the reaction, extracting with ethyl acetate (10mL multiplied by 3), combining organic phases, and concentrating. Column chromatography (PE/EA ═ 1:1) gave the compound as a white solid (241mg,0.70mmol, 70% overall yield), while a small amount of the natural product LA (18mg,0.05mmol, 5% overall yield) was obtained.

Fourthly, the general method: laxiflorin B (or other natural products) (17mg, 0.05mmol) is dissolved in 1mL dichloromethane, a 5-alkynyl valeric acid module (0.05mmol), EDCI (0.05mmol) and DMAP (cat.) are sequentially added, the reaction is continued for 12 hours at room temperature, TLC detects that the reaction raw materials completely disappear, saturated sodium bicarbonate aqueous solution is added to quench the reaction, ethyl acetate (10mL multiplied by 3) is used for extraction, organic phases are combined and concentrated.

Fifthly, separating by column chromatography (PE/EA is 1:1) to obtain the terminal alkynyl derivative. The crude product was dissolved in 3mL of a mixed solvent (THF/H2O ═ 2:1), the known compound N3-PEG2-Biotin (0.05mmol) and sodium carboxymethylcellulose (0.005mmol) were added in this order, ultrasonic degassing was performed 3 times, copper sulfate pentahydrate (0.005mmol) was added under argon protection, and the reaction was carried out at room temperature for 12 hours until the reaction material was completely disappeared by TLC. The reaction was quenched by addition of saturated aqueous sodium bicarbonate solution, extracted with ethyl acetate (10mL × 3), and the organic phases were combined and concentrated.

And (4) analyzing results:

column chromatography (MeOH/DCM ═ 1:10) afforded the product (35mg,0.042mmol, 84% overall yield). 1H NMR (500MHz, Methanol-d4) δ 7.92(t, J ═ 5.6Hz,1H),7.85(s,1H),6.78(d, J ═ 10.2Hz,1H),5.96(s,1H),5.88(d, J ═ 10.2Hz,1H),5.59(s,1H),4.71(d, J ═ 11.3Hz,1H),4.65(d, J ═ 11.3Hz,1H),4.56(t, J ═ 5.1Hz,2H),4.49(dd, J ═ 7.9,4.8Hz,1H),4.41(dd, J ═ 13.0,3.8Hz,1H), 4.38-4.27 (m,2H),3.89(t, J ═ 1.8Hz, 1H), 4.38-4.27 (m,2H),3.89(t, 3.59, 3.3.3.59, 3.3.3.3H, 3.3.9, 3.3.3H, 3.59, 3.3H, 3.3, 3H, 3.9, 3.5H, 3.9, 3H, 3.9, 3.59 (dd, 3.3.9, 3.9, 3H, 3.9, 3, 3.5H, 3H, 2.81-2.64 (M,4H),2.42(t, J ═ 4.3Hz,1H),2.36(dt, J ═ 10.1,6.1Hz,3H),2.28(td, J ═ 14.8,13.6,5.9Hz,2H),2.21(t, J ═ 7.4Hz,2H), 2.05-1.91 (M,2H), 1.79-1.54 (M,6H), 1.51-1.37 (M,3H),1.28(s,3H),1.23(s,3H), 13C NMR (125MHz, MeOD) δ 202.4,199.8,174.7,172.6,170.7,164.6,159.1,151.2,146.6,123.7,122.8,118.5,70.0,69.8,69.8,69.2,69.0,62.0,60.3,60.2,58.5,55.6,51.5,49.9, 44.42, 69.8,69.8,69.2,69.0,62.0,60.3,60.2,58.5,55.6,51.5, 19.9, 19.38, 19.35, 19.9, 19.35, 19.9, 19, 19.9, 19, 19.9, 19.35, 19.9, 3, 19.9, 19, 3, 19.9, 3, 19.9, 19, 3, 19.9, 3, 19.9, 3, 19.9, 3, 19, 3, 19.9, 3, 19, 3, 19, 3,2, 3, 2.

LA-Biotin: 33mg,0.04mmol, overall yield 80%. 1H NMR (500MHz, Methanol-d4) δ 7.83(s,1H),6.75(d, J-10.2 Hz,1H),5.85(d, J-10.2 Hz,1H),5.07(dt, J-10.7, 1.8Hz,2H),4.85(s,2H), 4.68-4.53 (m,3H), 4.52-4.43 (m,2H), 4.44-4.33 (m,2H),4.31(dd, J-7.9, 4.5Hz,1H),3.90(t, J-5.1 Hz,2H), 3.70-3.54 (m,4H),3.51(t, J-5.6, 2H), 3.36-3.28 (m,7H),3.21 (t, 3.21, 7.8, 4.7H), 7.7H, 7H, 7.8 (d, 4H), 4H), 7.7.7, 7.8, 4H, 7.7H, 7H, 4H, 7H, 7.9 (dd, 2H), 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 4H, 7H, 2H, 4H, 7H, 4H, 7H, 2H, 7H, 4H, 7H, 2H, 7H, 4H, 7H, 2H, 7H, 4H, 2H, 7H, 2H, 7H, 2H, 5, 4H, 2H, 7H, 5H, 4H, 2H, 7H, 4H, 2H, 4H, 2H, 7H, 2H, 5H, 2H, 7H, 2H, 4H, 2H, 7H, 5, 2H, 7H, 2H, 7H, 4H, 7, 2H) 2.09-1.87 (M,2H), 1.80-1.55 (M,4H),1.44(t, J ═ 7.7Hz,4H),1.27(s,3H),1.21(s,3H).13C NMR (125MHz, MeOD) δ 201.1,176.8,174.7,172.9,164.6,159.2,158.8,146.8,123.9,122.8,108.4,81.6,70.0,69.8,69.4,69.2,69.0,62.0,60.6,60.2,55.6,52.3,51.0,49.9,44.5,39.7,38.9,36.1,36.0,35.3,34.8,33.1,32.8,30.6,30.1,28.3,28.1,25.4,24.3,24.2,22.6,16.4.HRMS (ESI/[ M + Na ] +) calc 56H 42, 36 863.3984, 863.3987, N6335, N42, 863.3987, N48, N.

LB-Di-Biotin: 32mg,0.038mmol, overall yield 76%. 1H NMR (400MHz, DMSO-d6) δ 7.81(s,1H),7.77(t, J ═ 5.6Hz,1H),6.37(s,1H),6.32(s,1H),4.71(d, J ═ 11.6Hz,1H),4.45(t, J ═ 5.3Hz,2H), 4.33-4.25 (m,2H),4.24(dd, J ═ 12.6,3.8Hz,1H), 4.19-4.07 (m,2H),3.78(t, J ═ 5.3Hz,2H),3.50(dd, J ═ 6.2,3.6Hz,3H),3.46(dd, J ═ 6.0,3.5Hz,2H),3.35(t, J ═ 5.9, J ═ 6.2,3.6Hz,3H),3.46(dd, J ═ 6.0,3.5Hz,2H),3.35(t, J ═ 5, 2H), 3.9, 3.2H, 7.5H, 5H, 3.5 (dd, 5H), 3.9, 3.5H), 3.5, 5, 3.5H, 5H), 3.9, 5H, 3.7.5H, 5, 3.9, 5, 3.7.9, 5H, 3.9, 5H, 1H),3.9, 5H, 1H, 5H, 1H, 5H, 1H, 5H, 1H, 3.9, 5H, 1H, 5H, 1H, 5H, 1H, 5H, 1H, 5H, 1H, 5H, 4, 1H, 3.9, 5H, 3.9, 1H, 5H, 1H, 5H, 5,4, 1H, 5H, 3, 5H, 1.90-1.78 (M,2H),1.74(dt, J ═ 29.5,7.5Hz,1H), 1.62-1.52 (M,1H), 1.51-1.35 (M,3H),1.29(s,1H),1.23(s,2H), 1.08-0.99 (M,9H), 13C NMR (100MHz, DMSO) delta 217.1,212.1,172.8,172.7,169.8,163.3,146.5,122.9,70.1,70.0,69.7,69.4,68.9,61.9,61.6,59.8,58.9,56.0,53.7,49.8,48.3,47.6,43.1,39.0,37.1,36.7,35.7,33.6,32.2,31.5,28.8,28.6,25.8,24.9,24.8,24.2, 24.1, 17.12, 17.9, 17.12H, 17.9, 17.12H, 12H, 35.6, 3,6, 3,6, 32.2,3, 6,3, 6,3, 6,3, 6,3, 6,3, 19.5, 6,3, 6, 13.5, 19.5, 6, 19.5, 19, 19.5, 6, 19, 19.5, 19, 17, 19, 3, 19, 3, 19.

LB-Ala：(24mg,0.045mmol,90％)。¹H NMR(300MHz,Methanol-d₄)δ6.80(d,J＝10.2Hz,1H),6.01(s,1H),5.90(d,J＝10.2Hz,1H),5.62(s,1H),4.74(d,J＝11.3Hz,1H),4.67–4.45(m,3H),4.08(q,J＝7.3Hz,1H),3.16(dd,J＝9.3,4.8Hz,1H),2.71(d,J＝12.5Hz,1H),2.48(t,J＝4.2Hz,1H),2.38(dd,J＝12.3,4.6Hz,1H),2.29(dd,J＝12.4,5.2Hz,2H),1.78–1.40(m,5H),1.32–1.12(m,7H).¹³C NMR(75MHz,MeOD)δ202.5,199.1,170.3,169.2,158.6,150.9,143.0,123.5,118.2,90.1,69.3,62.3,58.1,51.1,44.1,41.9,36.0,34.7,30.1,29.7,29.3,24.3,22.5,17.3,14.4.HRMS(ESI/[M+H]⁺)calcd.for C₂₃H₃₀NO₆:416.2068,found 416.2074.

Example 7

Drug protein pull-down experiments:

the test process comprises the following steps:

1. the biotin-labeled Laxiflorin B, Laxiflorin A, Eriocalyxin B, Laxiflorin J and Laxiflorin B-Di are combined with magnetic beads coupled with streptomycin at 4 ℃ for 16 hours for later use.

2. Overexpression of the recombinant proteins Flag-ERK1WT, Flag-ERK1 in HEK293T cells^C178A(cysteine at position 178 mutated to alanine), Flag-ERK1^C183A(mutation of cysteine at position 183 to alanine), Flag-ERK1^C178A/C183A(cysteine mutated to alanine at positions 178 and 183) and total cellular protein was extracted after 48 hours.

3. After incubating the four recombinant proteins with the magnetic bead complexes of the five compounds for 16 hours at 4 ℃, the four recombinant proteins were vortexed in PBS containing 2% SDS for 20 seconds, and washing was repeated three times.

4. Western blot is used for detecting a recombinant protein Flag label pulled down by the compounding of the magnetic beads of the five compounds to judge the important position of the structure on Laxiflorin B.

And (4) analyzing results:

(1) in FIG. 8, Laxiflorin A is a Laxiflorin B analog that removes the D-ring activity; eriocalyxin B is a spatially structured Laxiflorin B analog; laxiflorin J is a Laxiflorin B analogue with the activity of removing the A ring; laxiflorin B-DI is Laxiflorin B analogue with the activity of removing A ring and D ring, biotin is connected to the 6 th carbon position respectively, and the activity of the A ring or D ring of the compound is not influenced.

(2) In FIG. 9, FIG. 9(A) and FIG. 9(B), wild-type ERK1(ERK 1) was observed in the pull-down experiment^WT) Can be strongly combined with Laxiflorin A, Laxiflorin B and Laxiflorin J, and the two have A ring or D ring, which indicates that Laxiflorin B is combined with ERK1 by utilizing the A ring or the D ring, while Eriocalyxin B with different three-dimensional space structures has poorer combining capability, if the A ring and the D ring are simultaneously combinedAfter disruption, Laxiflorin B-DI had the least binding to ERK 1.

In FIGS. 9A and 9B, Laxiflorin B is the strongest when 183 cysteine among ATP pocket positions is left after cysteine at position 178 of ERK1 is mutated to alanine, and then Eriocalyxin B and Laxiflorin J are shown, indicating that the three-dimensional structures of the D ring and the compound are important for Laxiflorin B to bind to ERK1, compared to Laxiflorin B-DI which lacks only the A ring.

In fig. 9(a) and 9(B), when 183 th cysteine in the ATP pocket position of ERK1 was mutated into alanine, it was found that Laxiflorin a having only a loop had the strongest binding ability, indicating that 178 th cysteine far from the position of ERK1 active pocket had a higher binding probability with a loop, and also because 178 th cysteine was far from the position of ERK1 active pocket, no tumor-inhibiting activity was found in combination with ERK1, while Laxiflorin B has a complete a loop, so that about half Laxiflorin B would bind with 178 th cysteine, resulting in loss of efficacy of Laxiflorin B, regardless of eriocalysin B, Laxiflorin J having only a D loop, or Laxiflorin B-DI lacking in a loop D loop, and cannot bind with 178 th cysteine.

In FIGS. 9A and 9B, if the cysteines 178 and 183 of ERK1 were mutated to alanine, then neither Laxiflorin B, Laxiflorin A, Eriocalyxin B, Laxiflorin J, or Laxiflorin B-Di could bind, indicating that these two cysteine sites of ERK1 are important for the binding of Laxiflorin B analogs.

In summary, Laxiflorin B covalently binds to the 183 th cysteine in the ATP pocket position of ERK1 through the D-ring double bond structure on the structure, occupies the ATP pocket, inhibits binding of ERK1 and ATP and activation of ERK1, and further exerts an effect of inhibiting tumor cell growth. Laxiflorin A can be selectively combined with an ERK inactive site by utilizing an A ring, can become a novel micromolecule probe of a target ERK, and provides a micromolecule guide group for protein modification and marking research of the target ERK kinase.

Example 8

Computer simulation analysis is utilized to prove the interaction of Laxiflorin B and target protein

The test process comprises the following steps:

(1) the three-dimensional structures of ERK1 and ERK2 were extracted from the experimental structures encoded as 6GES and 6G54 by the PDB database (https:// www.rcsb.org /) for preparation of molecular docking. Laxiflorin B was covalently linked to cysteine 183 and cysteine 166 of ERK1 and Ekr2, respectively, using HADDOCK2.2 Web docking software (https:// alcazar. science. u.n1/services/HADDOCK2.2/), taking into account the different orientations ("out" and "inner") at which Laxiflorin B binds. By cluster analysis and scoring function sorting, HADDOCK2.2 outputs 3 major complexes of ERK1 bound to the "inner" configuration of Laxiflorin B, 1 major complex of ERK1 bound to the "out" configuration of Laxiflorin B, 4 major complex of ERK2 bound to the "inner" configuration of Laxiflorin B, and 5 major complex of ERK2 bound to the "out" configuration of Laxiflorin B. And (3) carrying out artificial inspection on various structures by using PYMOL and other visualization software, and respectively selecting the structures to carry out subsequent molecular dynamics simulation research.

(2) Laxiflorin B is covalently coupled to a semilucent amino acid and is a nonstandard amino acid, and the force field parameters of Laxiflorin B are prepared by the following steps: firstly, calculating the surface potential of Laxiflorin B by using Gaussian09 software, wherein the calculation method and the basic group are HF/6-31G; fitting Laxiflorin B and point charges of covalently bound semilight amino acids thereof by applying an RESP module in an AMBER16 software package aiming at the surface potential output by Gaussian 09; thirdly, using ANTECHAMBER module in AMBER16 software package to prepare Laxiflorin B and parameter file of covalent binding semioptical amino acid thereof, and selecting GAFF2 by force field parameter.

(3) Preparation of ERK1/ERK2 parameters: experimental structures encoded as 6GES and 6G54 in the PDB database were used for the starting structures for ERK1 and ERK2 simulations, respectively, and only the P25-G374 amino acid fragment in 6GES and the G10-P356 fragment in 6G54 were involved in the simulations of ERK1 and ERK2 due to the deletion of part of the N-and C-terminal amino acids in the experimental structures. The protonation state of histidine was determined, which in this term was taken as the default state in AMBER 16. The parameters for all amino acids were derived from the FF14SB force field in AMBER16 software package.

(4) The parameters of tleap integration ERK1/ERK2 and Laxiflorin B in AMBER16 software package are used, and the flow is as follows: firstly, parameter files of ERK1/ERK2 and Laxiflorin B are respectively imported by using tleap, and the representative structure selected in the step 1 is imported. Secondly, adding a water tank on the surface of ERK1/ERK2, wherein the size of the water tank is

And thirdly, adding neutralizing ions into the whole system. And fourthly, outputting a parameter file and a coordinate file of the system, and preparing a dynamic simulation.

(5) The dynamic simulation is carried out by using a PMEMD module in AMBER16, and the simulation process is as follows: firstly, heavy atoms of ERK1/ERK2 and Laxiflorin B are limited, and water molecules and hydrogen atoms are optimized until energy is converged. And secondly, optimizing the whole system until the energy is converged without any limitation. And thirdly, limiting heavy atoms of ERK1/ERK2 and Laxiflorin B, wherein in the NVT ensemble, the temperature of the whole system is increased from 0K to 300K within 1 ns. And fourthly, removing all limits, and simulating the whole system for 2ns at the temperature of 300K in the NPT ensemble to optimize the whole system. And fifthly, performing 200ns dynamic simulation on the whole system, and storing and analyzing the simulation track.

(6) The effect of amino acid phosphorylation modifications at positions 185 and 187 in ERK2 on Laxiflorin B binding was simulated. The parameters of ERK2 and Laxiflorin B were kept constant, and the phosphorylation parameters were from AMBER website (http:// ambermd. org /). The parameter preparation and simulation process is consistent with the process, the system is simulated for 200ns, and the track is saved for analysis.

And (4) analyzing results:

the results of molecular docking are shown in fig. 10 and fig. 11, wherein fig. 10 is the results of molecular docking of Laxiflorin B with ERK1, and fig. 11 is the results of molecular docking of Laxiflorin B with ERK 2.

The molecular docking finds that: laxiflorin B can form covalent bonds with 183 of ERK1 and 166 th amino acids of ERK2 and well binds in binding pockets of ERK1 and ERK2 in both 'inner' and 'out' configurations. The docking results of Laxiflorin B with different configurations are slightly different from those of ERK1 and ERK2, wherein when Laxiflorin B is in an 'inner' configuration, no hydrogen bond exists between Laxiflorin B and ERK 1; when interfacing with ERK2, the O5 oxygen atom of Laxiflorin B forms a hydrogen bond with the glutamine 105 side chain of ERK 2. When Laxiflorin B is in an 'out' configuration and is in butt joint with ERK1, an O7 oxygen atom of Laxiflorin B and a 171-position asparagine side chain of ERK1 form a hydrogen bond; no hydrogen bond with ERK 2.

Further, the binding sites of Laxiflorin B on the surfaces of ERK1 and ERK2 are consistent through kinetic simulation. As shown in fig. 10 and 11, the binding pattern of the "out" configuration is consistent whether in the binding pocket of ERK1 or ERK2, with the O7 oxygen atom of Laxiflorin B forming stable hydrogen bonds with the 128 th aspartic acid side chain of ERK1 or 111 th aspartic acid side chain of ERK 2. While the "inner" configuration presents a different binding pattern in 3 within the binding pocket of ERK1, the binding pattern in ERK2 is consistent with the "out" configuration.

The dynamic simulation finds that the phosphorylation modification of amino acids 185 and 187 of ERK2 has certain influence on the binding mode of Laxiflorin B. The binding pattern of Laxiflorin B in 185 th and 187 th phosphorylation modified ERK2 was consistent, but different from before phosphorylation modification. After phosphorylation modification, the hydrogen bond between O7 oxygen atom of Laxiflorin B and 111 th aspartic acid side chain is broken, but O5 oxygen atom and 35 th alanine of ERK2 form hydrogen bond interaction.

Example 9

Animal experiment analysis proves that the Laxiflorin B-Ala with better water solubility and formula I-10 has the cancer inhibiting effect

The experimental procedure is shown in fig. 12 (a):

(1) PC9 cells were cultured at 5X10⁶Concentration of mice/mice were inoculated subcutaneously into nude mice in an injected manner and allowed to grow for 1 week.

(2) Normal saline was administered to the control group, and Laxiflorin B-Ala at 5, 10, and 20mg/kg was administered to the experimental group, respectively, by intraperitoneal injection daily for 3 weeks, and tumor size and mouse body weight were measured every two days to monitor drug toxicity.

(3) Three weeks later, the tumor and internal organs on the back of the mice were removed and photographed by weighing.

And (4) analyzing results:

FIG. 12(B) shows that Laxiflorin B-Ala inhibits tumor growth, and Laxiflorin B inhibits tumor growth effectively in three weeks, as can be seen from FIG. 12 (B).

Fig. 13(a) is a photograph of the tumor three weeks after administration, and fig. 13(B) is a graph of tumor weight quantification and statistical analysis results.

FIG. 14(A) is a body weight test of mice administered for three weeks, and it can be seen that there was no significant decrease in body weight and that the mice did not significantly lose their lean due to administration of Laxiflorin B. FIG. 14(B) is a statistical plot of the weights of mouse heart, kidney and liver divided by the individual body weight, and there was no significant difference between the experimental group and the control group, indicating that Laxiflorin B is less toxic to mice. (p < 0.05;. p < 0.01;. p <0.001)

Example 10

Preparation of ERK1/2 inhibitor of structural formula I-2-I-10

The test process comprises the following steps:

(1) general procedure for analog preparation: dissolving Laxiflorin B serving as a raw material in dichloromethane, and mixing the raw material with the weight ratio of 1: adding the corresponding acid compound module according to the proportion of 1, and cooling to 0 ℃. 1-Ethyl- (3-dimethylaminopropyl) carbonyldiimine hydrochloride (EDC. HCl) and 4-Dimethylaminopyridine (DMAP) were added, and the mixture was slowly warmed to room temperature to react for 3 hours. Detecting raw materials by chromatography, adding saturated sodium bicarbonate water solution to quench reaction, extracting with ethyl acetate for 3 times, mixing organic phases, washing with saturated saline solution, drying with anhydrous sodium sulfate, spin-drying the solvent under reduced pressure, and separating by flash column chromatography (petroleum ether: ethyl acetate) to obtain corresponding ERK1/2 inhibitor with structural formula I-2-I-10, with the structure shown in FIG. 15 (A).

(2) PC9 cells were seeded at 3000-.

(3) Adding Laxiflorin B analogues with different concentrations after the cells adhere to the wall, adding a CCK-8 color generation reagent after 48 hours, placing the mixture in an incubator at 37 ℃ and reacting for 2 hours.

(4) Absorbance readings at 450nm were measured with a microplate reader and inhibition plots were made in excel.

And (4) analyzing results:

as shown in FIG. 15(B), the concentration (μ M) of Laxiflorin B is shown on the X axis, the cell viability (%) is shown on the Y axis, when the concentration of the drug inhibits 50% of the cell viability, the drug is called the "half inhibitory dose" (IC50) of the drug to the cell, and compared with Laxiflorin B, the ERK1/2 inhibitors of the structural formula I-3, the structural formula I-4, the structural formula I-5, the structural formula I-6 and the structural formula I-8 have better inhibitory effects.

Example 11

Laxiflorin B effect analysis experiment (AREG, EREG as analysis index)

The test process comprises the following steps:

(1) PC9 or HCC827 cells were treated with DMSO or Laxiflorin B (4. mu.M) for 24 hours, and then RNA was recovered with Trizol reagent and inverted to cDNA. And then detecting by using AREG and EREG specific primers and analyzing the expression conditions of the two genes.

(2) PC9 or HCC827 cells were treated with Laxiflorin B at different concentrations for 48 hours, and total protein was collected and examined for the expression level of Ampheirulin (an AREG gene-auxotroph) or Epirerulin (an EREG gene product) by specific antibodies using Western Blot.

(3) In animal experiments, after tumors in the north of nude mice are taken out, paraffin is used for embedding and section processing, and the expression positions and the expression amounts of Amphierogulin (AREG gene product) and Epiregulin (EREG gene product) proteins in the tumors are detected in a specific antibody immunohistochemical mode.

And (4) analyzing results:

as shown in fig. 16(a) and 16(B), mRNA levels of AREG and EREG were significantly reduced in non-small cell lung cancer cells after Laxiflorin B treatment.

As shown in fig. 16(C), after treatment with different doses of Laxiflorin B, the expression levels of ampiriegulin (AREG gene product), Epiregulin (EREG gene product) protein levels in non-small cell lung cancer cells were significantly down-regulated and responded by dose-dependent.

Analysis of the expression positions and expression amounts of Ampheirulin (AREG gene product) and Epirerulin (EREG gene product) proteins in tumors is shown in FIG. 17, and after three weeks of treatment of tumors in nude mice with Laxiflorin B, the expression amounts of Ampheirulin (AREG gene product) and Epirerulin (EREG gene product) protein levels are significantly reduced through tissue section and immunohistochemistry analysis, consistent with the phenomenon in cells. In conclusion, the structural formula of the ERK1/2 inhibitor provided by the application is shown in formula I, the structural formula utilizes D-ring unsaturated double bonds on the structure to react with the 183/166 th cysteine at the position of the ERK1/2 kinase region pocket through Michael to generate stable and irreversible covalent bonds, and simultaneously, 3-5 hydrogen bond binding sites and matched hydrophobic effect and molecular shape are formed with amino acid residues around the ERK1/2 kinase region pocket, which are favorable for improving the binding capacity of the structural molecule and the target protein ERK1/2 action pocket and stabilizing the covalent small molecule-target protein binding product, so as to inhibit activation of ERK1/2 protein, further reduce the expression of AREG and EREG of target genes at the downstream of ERK, and feedback inhibit activation of EGFR and EGFR channels at the upstream, finally, the growth of cell lines and tumors activated by EGFR/MEK/ERK pathways is effectively inhibited, the cancer inhibition effect is achieved, and the compound has the potential of being applied to the preparation of anti-cancer drugs. The expression of AREG and EREG can be used as the therapeutic evaluation index of the ERK1/2 inhibitor and EGFR/MEK/ERK pathway block.

Meanwhile, in the preparation method of the ERK1/2 inhibitor, the eriocalyxin B is extracted from natural plants, the eriocalyxin B is taken as a raw material, and the eriocalyxin B is converted into the ERK1/2 inhibitor by a semisynthetic method, so that the raw material of the preparation method is easy to obtain, the cost is low, the operation is simple, and on one hand, compared with other artificially synthesized chemical inhibitors, the preparation method is lower in animal toxicity and safer; on the other hand, compared with the method for directly extracting Laxiflorin B from medicinal plants, the method can greatly improve the yield of Laxiflorin B and is easy to realize industrial production and application. In clinical application of Laxiflorin B, the expression levels of Amphieregulin (AREG gene product) and Epireregulin (EREG gene product) in blood or tissues can be used as evaluation indexes of the drug effect.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An ERK1/2 inhibitor is characterized in that the ERK1/2 inhibitor is Laxiflorin B and derivatives thereof, wherein the ERK1/2 inhibitor has a structural general formula shown in formula I,

wherein R is¹Selected from any one of H, alkyl ester, amino acid ester, aryl ester, heteroaryl ester, substituted aryl ester and substituted heteroaryl ester.

2. The ERK1/2 inhibitor according to claim 1, wherein R is¹Any one of the following substituents is selected from,

3. the ERK1/2 inhibitor according to claim 1, wherein the ERK1/2 inhibitor is covalently bound to the 183 rd cysteine and 166 th cysteine at the pocket position of the ERK1/2 kinase domain, respectively, and forms 3-5 hydrogen bonds to react with each other.

4. The ERK1/2 inhibitor according to any one of claims 1-3, wherein the ERK1/2 inhibitor further comprises at least one of pharmaceutically acceptable adjuvants, adjuvants and prodrugs.

5. A preparation method of an ERK1/2 inhibitor is characterized by comprising the following steps:

6. The method for preparing the ERK1/2 inhibitor according to claim 5, wherein the step of obtaining rabdosia pilifera medicinal material powder comprises: the method comprises the steps of obtaining a rabdosia macalyx medicinal material, carrying out air drying treatment on the rabdosia macalyx medicinal material, and then crushing the rabdosia macalyx medicinal material into rabdosia macalyx medicinal material powder with the mesh number of 10-60 meshes.

7. The method for preparing the ERK1/2 inhibitor as claimed in claim 5, wherein the step of performing reflux extraction treatment on the rabdosia eriocalyx medicinal material powder by using alcohol solution comprises: providing a methanol water solution with the volume percentage concentration of 80-85%, and carrying out reflux extraction treatment on the rabdosia maucocalyx medicinal material powder for 2 hours; then decompressing and recovering the methanol to concentrate the extract solvent until the volume percentage concentration of the methanol is 40-45 percent, and obtaining a reflux extraction product; and/or the presence of a gas in the gas,

the separation treatment adopts any one of chromatographic separation treatment, gel column separation treatment, recrystallization separation treatment and preparative liquid phase separation treatment.

8. The method for preparing the ERK1/2 inhibitor as claimed in claim 5, wherein the step of mixing the eriocalyxin B with an organic solvent for heat refluxing treatment comprises: mixing the eriocalyxin B, dichloromethane and a dess-Martin reagent, and heating and refluxing for 2-2.5 hours; and/or the presence of a gas in the gas,

the step of mixing the reflux product with a reducing agent for a reduction reaction comprises: dissolving the reflux product in a solvent with a volume ratio of (10-12): 1 to obtain a mixed solution; and cooling the mixed solution to 0 ℃, mixing with sodium borohydride, and carrying out reduction reaction for 30-40 minutes.

9. The preparation method of the ERK1/2 inhibitor as claimed in claim 5, wherein the purification treatment is performed by column chromatography separation.

10. The ERK1/2 inhibitor as set forth in any one of claims 1 to 4 or the ERK1/2 inhibitor as set forth in any one of claims 5 to 9, and the application of the ERK1/2 inhibitor prepared by the preparation method in preparing anticancer drugs.