Antitumor Compounds, Self-Assembled Nanodrug Delivery Systems of Antitumor Compounds and Preparation Methods Thereof

Abstract

The present invention belongs to the technical fields of medicinal chemistry and pharmaceutical preparations, and particularly relates to a class of anti-tumor compounds, a self-assembled nano drug delivery system of anti-tumor compounds, and a preparation method and application thereof. The present invention provides a class of novel anti-tumor compounds CPT-s-s-Lindqvist and CPT-c-c-Lindqvist and a preparation method thereof. The synthesis methods of the two compounds are simple, and the raw material costs are low. By preparing vesicles from CPT-s-s-Lindqvist or CPT-c-c-Lindqvist through the thin film hydration method, a self-assembled nano drug delivery system can be obtained, which can achieve precise drug release in tumor tissues, exhibit a certain sustained release effect, have good biosafety, and have a significant synergistic anti-tumor effect.

Description

Technical Field

[0001] The present invention belongs to the technical fields of medicinal chemistry and pharmaceutical preparations, and particularly relates to a class of anti-tumor compounds, a self-assembled nano-drug delivery system of anti-tumor compounds, and a preparation method and application thereof. Background Art

[0002] As an effective means of cancer treatment, chemotherapy is limited by poor drug solubility, insufficient stability, and non-specific delivery, resulting in the difficulty of accurately delivering drugs to the tumor site and inevitably damaging healthy cells. The characteristics of the tumor microenvironment include high concentrations of glutathione, hypoxia, low pH, etc. These factors together contribute to the resistance of tumor cells to treatment and may exacerbate the proliferation, migration, and invasion abilities of tumor cells.

[0003] Disulfide bonds are a class of reduction-sensitive chemical bonds that can be cleaved under the reducing action of glutathione in the human body. At the same time, it has been found that the concentration of extracellular glutathione (GSH) in human cells is very low, about 2 - 20 μmol / L, which is not sufficient to break disulfide bonds. However, the concentration of glutathione (2 - 10 mmol / L) in tumor cells is usually about 7 - 10 times higher than that in normal cells, which is sufficient to break disulfide bonds. The drug delivery system based on disulfide bonds triggers drug release by utilizing the highly expressed glutathione in tumor cells, thereby improving the therapeutic effect and reducing damage to normal cells.

[0004] Polyoxometalates, also known as polyacids, are composed of transition metal atoms (such as vanadium, molybdenum, tungsten, etc.) and heteroatoms (such as phosphorus, silicon, etc.) bridged by oxygen atom coordination. They have the characteristics of plastic structure, low toxicity, mature synthesis, and low cost. Polyacids exhibit broad-spectrum anti-tumor activity and induce apoptosis of tumor cells through multiple mechanisms such as increasing the intracellular ROS level, reducing anti-apoptotic components, inhibiting ATP synthesis, and inducing DNA damage. In particular, Lindqvist-type polyacids are becoming a hot spot in the anti-tumor research of polyacid drugs due to their good biocompatibility and cytotoxicity. Due to the negative charge on the surface of polyacids, adjacent ion clusters will form vesicles spontaneously through electrostatic force, van der Waals force, and hydrogen bond interactions. After covalently connecting Lindqvist-type polyacids with hydrophobic drugs, stable amphiphilic molecular vesicles are formed in aqueous solution, which can prolong the half-life in the blood and enhance the aggregation towards the tumor microenvironment through the enhanced permeability and retention (EPR) effect, preventing uptake by the reticuloendothelial system, which is beneficial for drug delivery and synergistic treatment.

[0005] Camptothecin (CPT) is a natural quinoline alkaloid. During the S phase of tumor cell DNA replication, camptothecin can specifically recognize and act on deoxyribonucleic acid TopoⅠ to form a stable "CPT-TopoⅠ-DNA" ternary complex. By inhibiting the activity of topoisomerase Ⅰ, the DNA synthesis of tumor cells is blocked, thereby mediating the death of tumor cells. However, due to the poor water solubility and bioavailability of camptothecin, its dosage is relatively high, resulting in strong toxic and side effects, which greatly limit its application as an anti-tumor drug in clinical practice. Summary of the Invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention modifies camptothecin with polyoxometalate, aiming to achieve the dual effects of enhancing efficacy and reducing toxicity, and significantly improving its water solubility.

[0007] The first object of the present invention is to provide an anti-tumor compound, which is a Lindqvist-type polyoxometalate-camptothecin hybrid compound.

[0008] The structural formula of the compound is: (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5].

[0009] Among them, (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2], abbreviated as CPT-s-s-Lindqvist in the present invention, is a glutathione-responsive camptothecin hybrid compound of Lindqvist-type polyoxometalate; (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5], abbreviated as CPT-c-c-Lindqvist in the present invention, is a Lindqvist-type polyoxometalate-camptothecin hybrid compound.

[0010] The second object of the present invention is to provide a preparation method of the above anti-tumor compound. Among them, the (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23[N2O5S2], which is prepared by linking camptothecin to Lindqvist polyoxometalate through 3,3'-dithiobipropionic acid;

[0011] The said (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5], which is prepared by linking camptothecin to Lindqvist polyoxometalate through suberic acid.

[0012] The said (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 The preparation method of [N2O5S2] comprises the following steps:

[0013] (1) Dissolve Na2WO4·2H2O, NaVO3 and tris(hydroxymethyl)aminomethane in purified water in turn, then heat and stir at 85 °C. After the mixture is completely dissolved, adjust the pH value of the solution to 2.5 - 3 with concentrated hydrochloric acid, and then continue to react for 24 hours to obtain an orange reaction solution; dissolve tetrabutylammonium bromide in ultrapure water, and slowly drop the orange reaction solution into the solution of tetrabutylammonium bromide drop by drop under stirring. An orange-yellow precipitate is precipitated from water, filtered, washed and dried to obtain an orange-yellow powdery solid, namely the amino-modified Lindqvist polyoxometalate (TBA)2[V3W3O 16 (CH2O)3CNH2];

[0014] (2) Dissolve camptothecin, 3,3'-dithiobipropionic acid, 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide in dichloromethane in turn, react at room temperature for 24 hours, filter, remove the solvent under reduced pressure, and purify the product by column chromatography to obtain CPT-s-s-COOH;

[0015] (3) Under nitrogen protection, dissolve 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) and CPT-s-s-COOH in acetonitrile in turn, then heat to reflux, react for 35 minutes, then add Lindqvist polyoxometalate to the reaction solution, and reflux for 24 hours; after the reaction is completed, cool the obtained orange reaction solution to room temperature and concentrate it under reduced pressure; drop the concentrated reaction solution into ethyl acetate to precipitate, and obtain the target product CPT-s-s-Lindqvist by filtration.

[0016] The above-mentioned (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23In [N2O5S2], the molar ratio of camptothecin, 3,3'-dithiodipropionic acid, 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide described in step (2) is: 1∶1 - 1.5∶0.5 - 1∶1 - 1.5, and the dosage ratio of camptothecin to dichloromethane is 1 g camptothecin∶50 - 100 mL dichloromethane. In step (3), the molar ratio of (TBA)2[V3W3O 16 (CH2O)3CNH2], CPT-s-s-COOH and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) is: 1∶1.5 - 2∶2 - 3, and the dosage of acetonitrile solvent is 1 g (TBA)2[V3W3O 16 (CH2O)3CNH2]∶50 - 100 mL acetonitrile solvent.

[0017] In the present invention, the synthesis route of CPT-s-s-Lindqvist is as follows:

[0018] (1)

[0019] (2)

[0020] (3)

[0021] The preparation method of the said (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] comprises the following steps:

[0022] (1) Dissolve Na2WO4·2H2O, NaVO3 and tris(hydroxymethyl)aminomethane in purified water in sequence, then heat and stir at 85 °C. After the mixture is completely dissolved, adjust the pH value of the solution to 2.5 - 3 with concentrated hydrochloric acid, and then continue to react for 24 hours to obtain an orange reaction solution; dissolve tetrabutylammonium bromide in ultrapure water, and slowly dropwise add the orange reaction solution into the solution of tetrabutylammonium bromide under stirring. An orange-yellow precipitate precipitates from the water. Filter by suction, wash, and dry to obtain an orange-yellow powdery solid, namely the amino-modified Lindqvist-type polyoxometalate (TBA)2[V3W3O 16 (CH2O)3CNH2];

[0023] (2) Dissolve suberic acid, camptothecin and 4-dimethylaminopyridine in tetrahydrofuran in sequence, and react at room temperature for 12 hours. Then wash, dry, filter, remove the solvent under reduced pressure, and purify the product by column chromatography to obtain the product CPT-c-c-COOH;

[0024] (3) Under nitrogen protection, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) and CPT-c-c-COOH were successively dissolved in acetonitrile, then heated to reflux for 35 minutes. Subsequently, Lindqvist-type polyoxometalate was added to the reaction solution and refluxed for 24 hours. After the reaction, the obtained orange reaction solution was cooled to room temperature and concentrated under reduced pressure. The concentrated reaction solution was dropped into ethyl acetate to precipitate, and the target product CPT-c-c-Lindqvist was obtained by suction filtration.

[0025] In the present invention, the synthesis route of CPT-c-c-Lindqvist is as follows:

[0026] (1)

[0027] (2)

[0028] (3)

[0029] In the preparation method of the above-mentioned (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5], the molar ratio of camptothecin, suberic acid, and 4-dimethylaminopyridine is: 1∶8 - 10∶0.5 - 1, and the dosage ratio of camptothecin to tetrahydrofuran is 1 g camptothecin∶20 - 50 mL tetrahydrofuran. In step (3), the molar ratio of (TBA)2[V3W3O 16 (CH2O)3CNH2], CPT-c-c-COOH, and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) is: 1∶1.5 - 2∶2 - 3, and the dosage of acetonitrile solvent is 1 g (TBA)2[V3W3O 16 (CH2O)3CNH2]∶50 - 100 mL acetonitrile solvent.

[0030] In the preparation method of the above-mentioned anti-tumor compound, in step (1), the molar ratio of Na2WO4·2H2O, NaVO3, and tris(hydroxymethyl)aminomethane is 1∶1 - 1.5∶0.5 - 1, and the dosage ratio of Na2WO4·2H2O to purified water is 1 g Na2WO4·2H2O∶10 - 15 mL purified water.

[0031] The third object of the present invention is to provide a self-assembled nano-drug delivery system based on the above-mentioned anti-tumor compound and its preparation method,

[0032] The self-assembled nano-drug delivery system is composed of (TBA)2[V3W3O 16 (CH2O)3CNHCOC25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] is prepared. The preparation method of the self-assembled nano drug delivery system includes the following steps: Take (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] and dissolve it in acetonitrile, sonicate for 10 min, use a rotary evaporator under reduced pressure to remove acetonitrile. Immediately put it in a water bath at 50 °C for heat preservation after the organic phase forms a thin film at the bottom of the round-bottom flask, add purified water at 50 °C to start hydration, and vesicles are obtained after 4 h of hydration.

[0033] The obtained vesicles are the self-assembled nano drug delivery system of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5].

[0034] In the above preparation method of the self-assembled nano drug delivery system of the anti-tumor compound, for every 1 mg of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] raw material, 5 - 10 mL of acetonitrile and 5 - 10 mL of purified water need to be added.

[0035] The fourth object of the present invention is to provide the application of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] in the preparation of anti-tumor drugs and (TBA)2[V3W3O 16 (CH2O)3CNHCOC25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 The application of the self-assembled nano-drug delivery system of [H2N2O5S2] or (TBA)2[V3W3O] in the preparation of anti-tumor drugs. The tumors are preferably lung cancer and liver cancer.

[0036] In the present invention, the term "vesicle": Amphiphilic molecules are dispersed in water. Under the action of hydrophobic forces, the hydrophilic ends face the water, the hydrophobic ends are away from the water, and intermolecular ordered aggregation occurs, thus spontaneously forming a class of molecular ordered aggregates with a closed bilayer structure, which is called a vesicle (Chen, X.; Dong, W.; Zhang, X. Science China-Chemistry. 2010, 53, 1853, Neuhaus, F.; Mueller, D.; Tanasescu, R.; Balog, S.; Ishikawa, T.; Brezesinski, G.; Zumbuehl, A. Angewandte Chemie International Edition. 2017, 56, 6515.).

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) The present invention provides a new class of anti-tumor compounds CPT-s-s-Lindqvist and CPT-c-c-Lindqvist and their preparation methods. The synthesis methods of the two compounds are simple, and the raw material costs are low. The solubility experiment results show that compared with camptothecin alone, the solubilities of CPT-s-s-Lindqvist compound and CPT-c-c-Lindqvist compound in water are significantly increased. This means that after camptothecin is connected with Lindqvist-type polyoxometalate, the water solubility of camptothecin can be improved. CPT-s-s-Lindqvist has better water solubility due to the introduction of a disulfide bond.

[0039] (2) The present invention provides CPT-s-s-Lindqvist and CPT-c-c-Lindqvist self-assembled nano drug delivery systems and their preparation methods. The self-assembled nano drug delivery systems are CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles. The vesicles are prepared by the thin film hydration method using CPT-s-s-Lindqvist or CPT-c-c-Lindqvist. After being diluted 1000 times for detection, the particle size of the drug-loaded vesicles remains stable, without obvious changes or vesicle depolymerization, and no drug precipitation phenomenon is found. Therefore, the drug-loaded vesicles have good dilution stability, possess the characteristics of an ideal delivery system, and can rapidly and efficiently enter target cells and tissues under non-steady-state conditions.

[0040] (3) The results of hemolysis experiments show that: within the range of 5 - 200 μg·mL -1 , neither CPT-s-s-Lindqvist vesicles nor CPT-c-c-Lindqvist vesicles have obvious hemolytic activity on red blood cells, have good biocompatibility, are suitable for intravenous administration, and have no adverse effects on the body. This indicates that the two types of vesicles have good blood compatibility.

[0041] (4) The CPT-s-s-Lindqvist vesicles of the present invention are glutathione-responsive camptothecin vesicles of Lindqvist-type polyoxometalate, and can be used for the targeted delivery of camptothecin and the release of drug in response to glutathione in tumor cells. In vitro release experiments show that CPT-s-s-Lindqvist vesicles stably exist in normal body fluids. When encountering high concentrations of glutathione in tumor cells, the disulfide bonds are rapidly broken, the vesicles disintegrate, and camptothecin and Lindqvist-type polyoxometalate are rapidly released. Compared with camptothecin and CPT-c-c-Lindqvist vesicles, this type of vesicle has a better anti-cancer effect, can achieve precise drug release in tumor tissues, shows a certain sustained-release effect, has good biosafety, and has a significant synergistic anti-tumor effect, solving the problem of poor therapeutic effect of single anti-tumor drugs.

[0042] (5) The results of cytotoxicity experiments on CPT-s-s-Lindqvist compounds and CPT-s-s-Lindqvist vesicles show that both CPT-s-s-Lindqvist and CPT-s-s-Lindqvist vesicles exhibit effective inhibition of the proliferation of A549 and Huh7 cancer cells. At the same time, they have high safety for normal cells such as HUVEC and HEK293, only showing low cytotoxicity. In addition, the anti-cancer effect of CPT-s-s-Lindqvist vesicles is better because the vesicle form is more easily taken up by cancer cells, thereby improving the bioavailability and anti-cancer efficiency of the drug.

[0043] The nano-drug delivery system of the present invention can self-assemble into nano-vesicles with uniform particle size in aqueous solution, which can prolong the circulation time of drugs in the blood and is easy to accumulate in tumor sites through the EPR effect. Compared with camptothecin and CPT-c-c-Lindqvist vesicles, CPT-s-s-Lindqvist vesicles can passively target the anti-cancer drug camptothecin and polyoxometalate into cancer cells, thereby achieving selective killing of cancer cells by anti-cancer drugs and reducing the toxic side effects on normal cells.

[0044] (6) The cell uptake experiments of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles showed that the uptake of drug vesicles by A549, Huh7, HUVEC and HEK293 cells was significantly higher than that of the free drug control group. CPT-s-s-Lindqvist vesicles significantly enhanced the cell uptake of drugs, especially in cancer cells. CPT-s-s-Lindqvist and CPT-c-c-Lindqvist vesicles successfully entered tumor cells and were mainly distributed in organelles such as lysosomes, verifying the effective uptake and localization of drug vesicles in tumor cells, thus supporting the potential application value of drug vesicles in anti-tumor therapy.

[0045] (7) The results of the cytotoxicity experiments of CPT-s-s-Lindqvist vesicle solution and CPT-c-c-Lindqvist vesicle solution showed that at the same concentration, both CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles showed good inhibitory effects on the proliferation of A549 and Huh7 cancer cells, and both had high safety for HUVEC and HEK293 normal cells. However, compared with CPT-c-c-Lindqvist vesicles, the inhibition rate of CPT-s-s-Lindqvist vesicles was higher. This is mainly due to the cleavage of disulfide bonds in the high-concentration glutathione environment in tumor cells, while such cleavage is relatively less in normal cells, thus significantly improving the safety and anti-cancer effect on normal cells.

[0046] (8) The amphiphilic CPT-s-s-Lindqvist vesicles obtained in the present invention achieve precise release of Lindqvist-type polyoxometalate and camptothecin through the trigger of glutathione in tumor tissues. The vesicles have multiple advantages such as synergistic anti-cancer, precise drug release, enhanced stability and solubility of camptothecin, enhanced permeability and EPR effect, and reduced toxic side effects, providing an innovative and efficient drug delivery scheme for cancer treatment. Description of the Drawings

[0047] Figure 1Schematic diagram of the preparation process of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles.

[0048] Figure 2 For CPT-s-s-Lindqvist and CPT-c-c-Lindqvist 1 1H NMR spectrum.

[0049] Figure 3 Infrared spectra of CPT-s-s-Lindqvist and CPT-c-c-Lindqvist.

[0050] Figure 4 TEM image of CPT-s-s-Lindqvist vesicles.

[0051] Figure 5 TEM image of CPT-c-c-Lindqvist vesicles.

[0052] Figure 6 Particle size distribution diagrams of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles.

[0053] Figure 7 Dilution stability of the particle size of CPT-s-s-Lindqvist vesicles.

[0054] Figure 8 Dilution stability of the particle size of CPT-c-c-Lindqvist vesicles.

[0055] Figure 9 Hemolytic property of CPT-s-s-Lindqvist vesicles.

[0056] Figure 10 Hemolytic property of CPT-c-c-Lindqvist vesicles.

[0057] Figure 11 Fluorescence spectral changes of CPT-s-s-Lindqvist vesicles before and after being activated by glutathione in PBS solution.

[0058] Figure 12 In vitro release experiment of CPT-s-s-Lindqvist vesicles.

[0059] Figure 13 In vitro release experiment of CPT-c-c-Lindqvist vesicles.

[0060] Figure 14Graph showing the effects of camptothecin, Lindqvist-type polyoxometalate, CPT-s-s-Lindqvist compound, and CPT-s-s-Lindqvist vesicles on different types of tumor cells and normal cells.

[0061] Figure 15 Uptake rates of CPT and CPT-s-s-Lindqvist vesicles by A549, Huh7, HUVEC, and HEK293 cells.

[0062] Figure 16 Intracellular distribution of FITC-labeled CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles observed by CLSM.

[0063] Figure 17 Graph showing the effects of camptothecin, Lindqvist-type polyoxometalate, CPT-c-c-Lindqvist vesicles, and CPT-s-s-Lindqvist vesicles on different types of tumor cells and normal cells.

[0064] Table 1: Comparison of the cell inhibition rates of CPT-s-s-Lindqvist vesicles, CPT-s-s-Lindqvist compound, and camptothecin alone on tumor cells and human normal cells at the same concentration.

[0065] Table 2: IC 50 values of camptothecin, Lindqvist-type polyoxometalate, CPT-s-s-Lindqvist compound, and CPT-s-s-Lindqvist vesicles on A549, Huh7, HUVEC, and HEK293 cells.

[0066] Table 3: Comparison of the cell inhibition rates of CPT-s-s-Lindqvist vesicles, CPT-c-c-Lindqvist vesicles, and camptothecin alone on tumor cells and human normal cells at the same concentration.

[0067] Table 4: IC 50 values of camptothecin, Lindqvist-type polyoxometalate, CPT-c-c-Lindqvist vesicles, and CPT-s-s-Lindqvist vesicles on A549, Huh7, HUVEC, and HEK293 cells. Detailed implementation methods

[0068] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. This is to enable those skilled in the art to better understand the present application, but these embodiments are only for illustrating the present invention and not for limiting the scope of the present invention. Moreover, unless otherwise specified, the numbers of the method steps are only convenient tools for identifying the method steps, rather than for limiting the arrangement order of the method steps or the scope in which the present invention can be implemented. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope in which the present invention can be implemented.

[0069] To better understand the above technical solution, the exemplary embodiments of the present invention will be described in more detail below. Although the exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0070] In the following embodiments, the test methods, unless otherwise specified, are all conventional methods; the reagents and biological materials, unless otherwise specified, can all be obtained from commercial channels.

[0071] Example 1, Preparation of CPT-s-s-Lindqvist compound

[0072] (1) Dissolve Na2WO4·2H2O (3.30 g, 10 mmol), NaVO3 (1.22 g, 10 mmol) and tris(hydroxymethyl)aminomethane (0.61 g, 5 mmol) in 35 mL of purified water in sequence, then heat and stir at 85 °C. After the mixture is completely dissolved, adjust the pH value of the solution to 2.5 - 3 with concentrated hydrochloric acid, and then continue the reaction for 24 hours to obtain an orange reaction solution.

[0073] Dissolve tetrabutylammonium bromide (2.2 g, 6.8 mmol) in 5 mL of ultrapure water. While stirring, slowly drop the orange reaction solution into the solution of tetrabutylammonium bromide drop by drop. An orange-yellow precipitate precipitates from the water. Filter by suction, wash, and dry to obtain an orange-yellow powdery solid, namely the amino-modified Lindqvist-type polyoxometalate (TBA)2[V3W3O 16 (CH2O)3CNH2].

[0074] (2) Camptothecin (3.5 g, 10 mmol), 3,3'-dithiodipropionic acid (2.3 g, 11 mmol), 4-dimethylaminopyridine (1 g, 8.2 mmol), and N,N'-dicyclohexylcarbodiimide (3 g, 14.5 mmol) were successively dissolved in 200 mL of dichloromethane and reacted at room temperature for 24 hours. After filtration and removal of the solvent under reduced pressure, the product was purified by column chromatography with a mobile phase of dichloromethane:methanol = 30:1 to obtain a pale yellow solid CPT-s-s-COOH.

[0075] (3) Under nitrogen protection, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (1.11 g, 4.5 mmol) and CPT-s-s-COOH (1.62 g, 3 mmol) were successively dissolved in 200 mL of acetonitrile, and the temperature was raised to the reflux state for 35 minutes. Then, Lindqvist-type polyoxometalate (2.34 g, 1.5 mmol) was added to the reaction solution and refluxed for 24 hours. After the reaction, the resulting orange reaction solution was cooled to room temperature and concentrated under reduced pressure. The concentrated reaction solution was dropped into 400 mL of ethyl acetate to precipitate, and the precipitate obtained by suction filtration was dissolved in a small amount of acetonitrile and placed in an ether vapor to precipitate, finally obtaining the target product CPT-s-s-Lindqvist.

[0076] Example 2, Preparation of CPT-c-c-Lindqvist compound

[0077] (1) Na2WO4·2H2O (3.30 g, 10 mmol), NaVO3 (1.22 g, 10 mmol), and tris(hydroxymethyl)aminomethane (0.61 g, 5 mmol) were successively dissolved in 35 mL of purified water, and then heated and stirred at 85 °C. After the mixture was completely dissolved, the pH value of the solution was adjusted to 2.5 - 3 with concentrated hydrochloric acid, and then reacted for another 24 hours to obtain an orange reaction solution.

[0078] Tetrabutylammonium bromide (2.2 g, 6.8 mmol) was dissolved in 5 mL of ultrapure water. Under stirring, the orange reaction solution was slowly added dropwise to the solution of tetrabutylammonium bromide, and an orange-yellow precipitate was precipitated from the water. After suction filtration, washing, and drying, an orange-yellow powdery solid, namely amino-modified Lindqvist-type polyoxometalate (TBA)2[V3W3O 16 (CH2O)3CNH2].

[0079] (2) Sebacic acid (9.91 g, 57 mmol), camptothecin (2 g, 5.7 mmol), and 4-dimethylaminopyridine (0.35 g, 2.9 mmol) were successively dissolved in 100 mL of tetrahydrofuran and reacted at room temperature for 12 hours. Then it was washed with saturated NaHCO3 aqueous solution (3 × 100 mL), 50 mM hydrochloric acid aqueous solution (1 × 100 mL), and saturated brine (1 × 100 mL). The organic layer was separated and dried over anhydrous sodium sulfate. After filtration and removal of the solvent under reduced pressure, the product was purified by column chromatography with the mobile phase of dichloromethane:methanol = 30:1 to obtain a pale yellow solid CPT-c-c-COOH.

[0080] (3) Under nitrogen protection, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (1.11 g, 4.5 mmol) and CPT-c-c-COOH (1.50 g, 3 mmol) were successively dissolved in 200 mL of acetonitrile, and the temperature was raised to reflux for 35 minutes. Then Lindqvist-type polyoxometalate (2.34 g, 1.5 mmol) was added to the reaction solution and refluxed for 24 hours. After the reaction, the obtained orange reaction solution was cooled to room temperature and concentrated under reduced pressure. The concentrated reaction solution was dropped into 400 mL of ethyl acetate to precipitate, and the precipitate obtained by suction filtration was dissolved in a small amount of acetonitrile and placed in ether vapor to precipitate, and finally the target product CPT-c-c-Lindqvist was obtained.

[0081] Appendix Figure 2 is the 1 1H NMR spectra of CPT-s-s-Lindqvist and CPT-c-c-Lindqvist. In the 1H NMR spectrum of CPT-s-s-COOH, δ 2.10 and δ 2.89 are characteristic peaks of the hydrogens on the two carbon atoms of the disulfide bond, indicating that the disulfide bond was successfully connected to CPT. For the 1H NMR spectrum of CPT-c-c-COOH, δ 4.20 and δ 3.79 are characteristic peaks of the hydrogens on the two carbon atoms. δ 3.95 and δ 5.30 belong to tris(hydroxymethyl)aminomethane connected to the polyoxometalate, indicating that the polyoxometalate successfully achieved amino modification. The characteristic peak around δ 8.70 in the 1H NMR spectra of CPT-s-s-Lindqvist and CPT-c-c-Lindqvist corresponds to the hydrogen atoms in the benzene ring of CPT. In addition, it also contains characteristic peaks of the polyoxometalate and the CPT-modified compound, proving the successful synthesis of the two substances.

[0082] Appendix Figure 3 are the infrared spectra of CPT-s-s-Lindqvist and CPT-c-c-Lindqvist. The strong absorption peaks around 800 - 960 cm -1 are the stretching vibrations of V-O and W-O bonds, which are consistent with the typical Lindqvist polyoxometalate structure. The absorption peak at 960 cm-1 There are strong stretching vibration peaks of V=O and W=O nearby. In the infrared spectrum of the CPT modifier, 3430 cm -1 is the stretching vibration peak of -OH, and 2929 cm -1 , 2849 cm -1 are the stretching vibration peaks of CH on saturated C, and 1650 cm -1 is the stretching vibration peak of C=O on the formed ester bond. The stretching vibration peak of C=O on the formed ester bond at 1650 cm -1 is more obvious, indicating the connection between Lindqvist polyoxometalate and CPT. Characteristic peaks of Lindqvist polyoxometalate appear in the final product, indicating the connection between CPT and Lindqvist polyoxometalate, and CPT-s-s-Lindqvist and CPT-c-c-Lindqvist are successfully synthesized.

[0083] Example 3. Preparation of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles by thin film hydration method

[0084] Weigh 2.0 mg of CPT-s-s-Lindqvist or CPT-c-c-Lindqvist compound, add 15 mL of acetonitrile and dissolve it completely. After ultrasonic treatment for 10 min, remove acetonitrile under reduced pressure using a rotary evaporator at 40 °C. Immediately put it into a water bath at 50 °C for 5 min after the organic phase forms a thin film at the bottom of the round-bottom flask. Add 10 mL of pure water at 50 °C to start hydration. After 4 h of hydration, CPT-s-s-Lindqvist vesicles or CPT-c-c-Lindqvist vesicles are obtained. A relatively regular hollow spherical nano-vesicle structure is observed by TEM ( Figure 4 and Figure 5 ). Then, the particle sizes of CPT-s-s-Lindqvist vesicles or CPT-c-c-Lindqvist vesicles are measured by a Malvern particle size analyzer to be about 250 nm and 230 nm respectively ( Figure 6 ).

[0085] Example 4. Preparation of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles by dialysis method

[0086] Accurately weigh 2 mg of CPT-s-s-Lindqvist or CPT-c-c-Lindqvist compound and dissolve it in 0.5 mL of acetonitrile. Then slowly drip it into a mixed solvent of 4.5 mL of acetonitrile (2 mL) and water (2.5 mL) so that the final mixing solution ratio is acetonitrile / water = 1 / 1 (v / v). Then transfer the mixed solution into a dialysis bag with a molecular weight of 1000 and dialyze for 24 hours to obtain CPT-s-s-Lindqvist vesicle solution or CPT-c-c-Lindqvist vesicle solution. The dialysis medium is ultrapure water.

[0087] Experimental Example 1: Solubility determination of CPT-s-s-Lindqvist and CPT-c-c-Lindqvist compounds

[0088] (1) Experimental basis: General Notices of Chinese Pharmacopoeia 2020 Edition

[0089] (2) Operating method: Weigh 1 g of camptothecin, Lindqvist-type polyoxometalate, CPT-s-s-Lindqvist compound, and CPT-c-c-Lindqvist compound ground into fine powder respectively, place them in a volumetric flask, add 10 mL of water (25°C ± 2°C) each time, shake vigorously for 30 seconds every 5 minutes; observe the dissolution situation within 30 minutes. If there are no visible solute particles or droplets, it is regarded as completely dissolved. If it is not dissolved, continue to add, and operate according to the above method each time until it is completely dissolved.

[0090] (3) Experimental results

[0091] Compound Solubility Camptothecin Extremely poorly soluble in water Lindqvist-type polyoxometalate 5.88 g / L CPT-s-s-Lindqvist 2.70 g / L CPT-c-c-Lindqvist 2.32 g / L

[0092] The results show that compared with camptothecin alone, the solubilities of CPT-s-s-Lindqvist compound and CPT-c-c-Lindqvist compound in water are significantly increased. This means that after camptothecin is connected with Lindqvist-type polyoxometalate, the water solubility of camptothecin can be improved. CPT-s-s-Lindqvist has better water solubility due to the introduction of disulfide bonds.

[0093] Experimental Example 2: Investigation of dilution stability of CPT-s-s-Lindqvist vesicle solution and CPT-c-c-Lindqvist vesicle solution

[0094] Take the CPT-s-s-Lindqvist vesicle solution and CPT-c-c-Lindqvist vesicle solution obtained by dialysis as the stock solutions and dilute them 0 times, 10 times, 100 times, and 1000 times respectively. Measure their particle size and particle size distribution to investigate whether the vesicles can always maintain the structural stability under different dilution multiples.

[0095] Attached Figure 7 And attached Figure 8 They are respectively the comparison of the particle size diagrams of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicle solutions at different dilution multiples. Through the detection of 1000-fold dilution, the particle sizes of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles still remained stable, without obvious changes and vesicle depolymerization, and no drug precipitation phenomenon was found. Therefore, this kind of drug-loaded vesicles has good dilution stability and the characteristic of vesicle depolymerization at low critical concentration, has the characteristics of an ideal delivery system, and can quickly and efficiently enter target cells and tissues under non-steady-state conditions.

[0096] Experimental Example 3: Hemolytic properties of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles

[0097] Collect mouse blood, dilute it with an equal volume of normal saline, and centrifuge to collect the particles containing red blood cells. The concentrated red blood cells are washed three times and then resuspended in PBS (pH 7.4) to obtain a 2% (v / v) red blood cell suspension. Add 1 mL of 2% red blood cell suspension to each centrifuge tube, and then add 3 mL of CPT-s-s-Lindqvist vesicle solution or CPT-c-c-Lindqvist vesicle solution with a concentration of 5 - 200 μg·mL -1 Water and phosphate buffered saline (pH 7.4) are used as positive (maximum hemolysis) and negative controls (minimum hemolysis). After incubation at 37 °C for 4 h, the above experimental groups and control groups are centrifuged. The absorbance values of the supernatants of the experimental groups and control groups at 578 nm are measured using an enzyme-linked immunosorbent assay (ELISA) reader.

[0098] Attached Figure 9 And attached Figure 10 Show the hemolytic properties of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles. The results show that within the range of 5 - 200 μg·mL -1 , neither CPT-s-s-Lindqvist vesicles nor CPT-c-c-Lindqvist vesicles have obvious hemolytic activity on red blood cells, have good biocompatibility, are suitable for intravenous administration, and have no adverse effects on the body. It shows that the two kinds of vesicles have good blood compatibility.

[0099] Experimental Example 4: In vitro drug release experiments of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles

[0100] A 10 μM CPT-s-s-Lindqvist vesicle solution was selected for measurement in PBS solvent (pH 7.4), incubated with different concentrations of glutathione at 37 °C for 1 h, and the fluorescence spectrum was measured using a fluorescence spectrophotometer.

[0101] The in vitro release behaviors of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles were studied in pH 7.4 + 10 mM GSH, pH 7.4 + 5 mM GSH, pH 7.4 + 10 μM GSH, and pH 7.4. A certain amount of freshly prepared CPT-s-s-Lindqvist vesicle or CPT-c-c-Lindqvist vesicle solution was transferred into a dialysis bag (MWCO: 1000 Da), and then placed in 50 mL of release medium at 37 °C and gently shaken at 100 rpm. At predetermined time points, 2 mL of the release solution was taken and an equal volume of fresh release medium was added. The CPT concentration was measured at 363 nm using an ultraviolet-visible spectrophotometer.

[0102] Appendix Figure 11 It shows the changes in the fluorescence spectrum of CPT-s-s-Lindqvist vesicles before and after being activated by glutathione in PBS solution. When the concentration of glutathione gradually increased, the fluorescence intensity of the solution at 425 nm increased significantly in a linear manner. The data indicate that the disulfide bond of CPT-s-s-Lindqvist can be cleaved by glutathione in a dose-dependent manner.

[0103] Appendix Figure 12 And Appendix Figure 13 They are the release curves of CPT from CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles in vitro in the presence of pH 7.4 + 10 mM GSH, pH 7.4 + 5 mM GSH, pH 7.4 + 10 μM GSH, and pH 7.4, respectively. pH 7.4, pH 7.4 + 10 mM GSH, and pH 7.4 + 10 μM GSH were used to simulate the blood circulation and intracellular and extracellular conditions. As a control, under the condition of 10 mM GSH, CPT-c-c-Lindqvist hardly released CPT within 48 hours. Under 10 mM GSH, CPT-s-s-Lindqvist vesicles rapidly released CPT in the tumor cell environment. The results show that CPT-s-s-Lindqvist vesicles have high stability and can achieve controlled drug release according to the changes in GSH in the tumor environment due to their disulfide bonds.

[0104] Experimental Example 5: Cytotoxicity Experiment of CPT-s-s-Lindqvist Compound and CPT-s-s-Lindqvist Vesicles

[0105] Test the inhibitory ability of CPT-s-s-Lindqvist compound and vesicles against lung cancer cells (A549) and liver cancer cells (Huh7), and the cytotoxicity against human normal cells human umbilical vein endothelial cells (HUVEC) and human embryonic kidney cells (HEK293).

[0106] Method: Digest, count the cells, and dilute them into a cell suspension with a concentration of 5×10 4 cells / mL. Then, inoculate 100 μL of the cell suspension into each well of a 96-well plate, and place the 96-well plate in an incubator at 37 °C and 5% CO2 for 24 hours. Next, dilute the CPT-s-s-Lindqvist vesicles with DMEM complete medium to different concentrations (20 μg·mL -1 , 40 μg·mL -1 , 60 μg·mL -1 , 100 μg·mL -1 , 200 μg·mL -1 ). Add 100 μL of the medium containing vesicles to each well. Set 3 replicates for each concentration, and set a blank group and a control group. The blank group does not inoculate cells, and the control group adds DMEM complete medium without vesicles. Then, place the 96-well plate in an incubator at 37 °C and 5% CO2 for 24 hours, add 10 μL of MTT to each well, and then incubate in the dark for 4 hours. Remove the medium, add 100 μL of dimethyl sulfoxide (DMSO) to each well, and gently mix on a shaker for 10 minutes. Finally, measure the OD value at 490 nm with an enzyme-linked immunosorbent assay (ELISA) reader to calculate the cell survival rate. The formula for calculating the cell survival rate is:

[0107]

[0108] Cell inhibition rate (%) = 1 - cell survival rate

[0109] The results are shown in Figure 14 and Table 1.

[0110] Table 1

[0111]

[0112] Table 1 shows that at 200 μg·mL -1The inhibition rates of CPT-ss-Lindqvist vesicles, CPT-ss-Lindqvist compounds and CPT were compared. The results showed that at the same concentration, both CPT-ss-Lindqvist and CPT-ss-Lindqvist vesicles showed effective inhibition of A549 and Huh7 cancer cell proliferation. At the same time, they were more safe for HUVEC and HEK293 normal cells, showing only low cytotoxicity. In addition, CPT-ss-Lindqvist vesicles have better anticancer effects, which is because the vesicle form is more easily taken up by cancer cells, thereby improving the bioavailability and anticancer efficiency of the drug.

[0113] Figure 14 The results in Table 1 show that the cell activity of normal cells HUVEC and HEK293 under the action of CPT-ss-Lindqvist vesicles and CPT-ss-Lindqvist compounds is higher than that of camptothecin alone. CPT-ss-Lindqvist vesicles break disulfide bonds in tumor cells, but not in normal cells. This makes it difficult for the drug to be released in normal cells, thereby reducing its toxicity to normal cells. IC of normal cells cultured for 24 hours with four drugs at different concentrations 50 (Table 2), the results indicate that CPT-ss-Lindqvist vesicles have better safety and can effectively reduce toxicity to normal cells.

[0114] Table 2

[0115]

[0116] Experimental Example 6: Cellular uptake experiment of CPT-ss-Lindqvist vesicles and CPT-cc-Lindqvist vesicles

[0117] Cellular uptake of fluorescein isothiocyanate (FITC)-labeled CPT-ss-Lindqvist vesicles and CPT-cc-Lindqvist vesicles was observed on a confocal laser scanning microscope (CLSM). Typically, cells were seeded in 6-well plates and cultured overnight. After an initial culture of 12 hours, CPT-ss-Lindqvist vesicles and CPT-cc-Lindqvist vesicles were introduced into the culture medium. After 8 hours of incubation, the cells were rinsed with PBS, fixed with 4% paraformaldehyde solution, and stained with Lyso-Tracker Red solution. Subsequently, the cells were observed using CLSM. Quantification was performed by flow cytometry.

[0118] Attached Figure 15Uptake rates of CPT and CPT-s-s-Lindqvist vesicles by A549, Huh7, HUVEC and HEK293 cells. The uptake of drug vesicles by A549, Huh7, HUVEC and HEK293 cells was significantly higher than that of the free drug control group. CPT-s-s-Lindqvist vesicles significantly enhanced the cellular uptake of drugs, especially in cancer cells.

[0119] Appendix Figure 16 Intracellular distribution of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles labeled with FITC under CLSM observation. CLSM imaging showed the co-localization of FITC signals with tumor cells, indicating that CPT-s-s-Lindqvist and CPT-c-c-Lindqvist vesicles successfully entered tumor cells and were mainly distributed in organelles such as lysosomes, verifying the effective uptake and localization of drug vesicles in tumor cells, thus supporting the potential application value of drug vesicles in anti-tumor therapy.

[0120] Experimental Example 7: Cytotoxicity experiment of CPT-s-s-Lindqvist vesicle solution and CPT-c-c-Lindqvist vesicle solution

[0121] Test the inhibitory ability of CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles prepared by the present invention on lung cancer cells (A549) and liver cancer cells (Huh7), and the cytotoxicity on human normal cells human umbilical vein endothelial cells (HUVEC) and human embryonic kidney cells (HEK293).

[0122] The results are shown in Figure 17 and Table 3.

[0123] Table 3

[0124]

[0125] Table 3 shows that at 200 μg·mL -1Inhibitory effects of CPT-s-s-Lindqvist and CPT-c-c-Lindqvist drug vesicles on cancer cells and normal cells. The results show that at the same concentration, both CPT-s-s-Lindqvist vesicles and CPT-c-c-Lindqvist vesicles exhibit good inhibitory effects on the proliferation of A549 and Huh7 cancer cells, and both have high safety for normal cells of HUVEC and HEK293. However, compared with CPT-c-c-Lindqvist, the inhibition rate of CPT-s-s-Lindqvist vesicles is higher. This is mainly due to the cleavage of disulfide bonds in the high-concentration glutathione environment in tumor cells, while this cleavage is relatively less in normal cells, thus significantly improving the safety for normal cells and the anti-cancer effect.

[0126] Table 4

[0127]

[0128] Figure 17 The results in Table 4 show that for human normal cells HUVEC and HEK293, the cell viability in the CPT-s-s-Lindqvist vesicle environment is higher than that in the CPT-c-c-Lindqvist vesicle environment and the camptothecin-alone environment. Combining the IC of normal cells cultured for 24 hours at different concentrations of the four drugs 50 (Table 4), it shows that CPT-c-c-Lindqvist vesicles have a certain safety and can effectively reduce the toxic effect on normal cells. CPT-c-c-Lindqvist vesicles show a certain cell proliferation inhibitory activity against the two cancer cells, but the anti-cancer effect is not as good as that of CPT-s-s-Lindqvist vesicles. This is because the CPT drug molecules cannot be efficiently released from the vesicles. This result also confirms that CPT-s-s-Lindqvist containing disulfide bonds can respond to the high concentration of glutathione in tumor cells and has a better anti-cancer effect and higher safety than CPT-c-c-Lindqvist.

Claims

1. An antitumor compound, which is a Lindqvist-type polyoxoacid-camptothecin hybrid compound, and is characterized in that, The structural formula of the said compound is: (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5]; The preparation method of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] comprises the following steps: (1) Dissolve Na2WO4·2H2O, NaVO3 and tris(hydroxymethyl)aminomethane in purified water in sequence, then heat and stir at 85 °C. After the mixture is completely dissolved, adjust the pH value of the solution to 2.5 - 3 with concentrated hydrochloric acid, and then continue to react for 24 hours to obtain an orange reaction solution; dissolve tetrabutylammonium bromide in ultrapure water, and slowly drop the orange reaction solution into the tetrabutylammonium bromide solution drop by drop under stirring. An orange-yellow precipitate precipitates from the water, filter by suction, wash, and dry to obtain an orange-yellow powdery solid, namely the amino-modified Lindqvist-type polyoxometalate (TBA)2[V3W3O 16 (CH2O)3CNH2]; (2) Camptothecin, 3,3'-dithiobispropionic acid, 4-dimethylaminopyridine, and N,N'-dicyclohexylcarbodiimide were successively dissolved in dichloromethane and reacted at room temperature for 24 hours. After filtration and removal of the solvent under reduced pressure, the product was purified by column chromatography to obtain CPT-s-s-COOH; (3) Under nitrogen protection, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) and CPT-s-s-COOH were successively dissolved in acetonitrile, then heated to reflux for 35 minutes. Subsequently, Lindqvist-type polyoxometalate was added to the reaction solution and refluxed for 24 hours; after the reaction, the resulting orange reaction solution was cooled to room temperature and concentrated under reduced pressure; the concentrated reaction solution was dropped into ethyl acetate to precipitate, and the target product was obtained by suction filtration; The preparation method of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] comprises the following steps: (1) Dissolve Na2WO4·2H2O, NaVO3 and tris(hydroxymethyl)aminomethane in purified water in sequence, then heat and stir at 85 °C. After the mixture is completely dissolved, adjust the pH value of the solution to 2.5 - 3 with concentrated hydrochloric acid, and then continue to react for 24 hours to obtain an orange reaction solution; dissolve tetrabutylammonium bromide in ultrapure water, and slowly dropwise add the orange reaction solution into the tetrabutylammonium bromide solution under stirring. An orange-yellow precipitate precipitates from the water, filter by suction, wash, and dry to obtain an orange-yellow powdery solid, namely the amino-modified Lindqvist-type polyoxometalate (TBA)2[V3W3O 16 (CH2O)3CNH2]; (2) Suberic acid, camptothecin, and 4-dimethylaminopyridine were successively dissolved in tetrahydrofuran and reacted at room temperature for 12 hours; then washed, dried, filtered, and the solvent was removed under reduced pressure. The product was purified by column chromatography to obtain CPT-c-c-COOH; (3) Under nitrogen protection, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) and CPT-c-c-COOH were successively dissolved in acetonitrile, then heated to reflux for 35 minutes. Subsequently, Lindqvist-type polyoxometalate was added to the reaction solution and refluxed for 24 hours; after the reaction, the resulting orange reaction solution was cooled to room temperature and concentrated under reduced pressure; the concentrated reaction solution was dropped into ethyl acetate to precipitate, and the target product was obtained by suction filtration.

2. The anti-tumor compound according to claim 1, wherein The described (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 In the preparation method of N2O5S2, in step (1), the molar ratio of the described Na2WO4·2H2O, NaVO3 and tris(hydroxymethyl)aminomethane is 1∶1~1.5∶0.5~1, and the dosage ratio of Na2WO4·2H2O to purified water is 1 g Na2WO4·2H2O∶10~15 mL purified water.

3. The anti-tumor compound according to claim 1, wherein The (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 In the preparation method of N2O5S2, in step (2), the molar ratio of camptothecin, 3,3'-dithiodipropionic acid, 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide is: 1∶1~1.5∶0.5~1∶1~1.5, and the dosage ratio of camptothecin to dichloromethane is 1 g of camptothecin∶50~100 mL of dichloromethane.

4. The anti-tumor compound according to claim 1, wherein The preparation method of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2], in step (3), the molar ratio of (TBA)2[V3W3O 16 (CH2O)3CNH2], CPT-s-s-COOH and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) is: 1∶1.5~2∶2~3, and the amount of acetonitrile solvent is 1 g of (TBA)2[V3W3O 16 (CH2O)3CNH2]∶50~100 mL of acetonitrile solvent.

5. The anti-tumor compound according to claim 1, characterized in that, The (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 In the preparation method of N2O5, the molar ratio of camptothecin, suberic acid and 4-dimethylaminopyridine in step (2) is: 1∶8~10∶0.5~1, and the dosage ratio of camptothecin to tetrahydrofuran is 1 g of camptothecin∶20~50 mL of tetrahydrofuran; In step (3), the molar ratio of (TBA)2[V3W3O 16 (CH2O)3CNH2], CPT-c-c-COOH and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) is: 1∶1.5 - 2∶2 - 3, and the amount of acetonitrile solvent used is 1 g of (TBA)2[V3W3O 16 (CH2O)3CNH2]∶50 - 100 mL of acetonitrile solvent.

6. The self-assembled nano drug delivery system of the anti-tumor compound according to claim 1, characterized in that, The self-assembled nano-drug delivery system is prepared from (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5]. The preparation method comprises the following steps: Take (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] and dissolve it in acetonitrile, sonicate for 10 min, use a rotary evaporator under reduced pressure to evaporate acetonitrile, immediately place it in a water bath at 50 °C for heat preservation after the organic phase forms a thin film at the bottom of the round-bottom flask, add purified water at 50 °C to start hydration, and vesicles are obtained after 4 h of hydration.

7. The self-assembled nano-drug delivery system of the anti-tumor compound according to claim 6, wherein In the preparation method, for every 1 mg of (TBA)2[V3W3O 16 (CH2O)3CNHCOC 25 H 23 N2O5S2] or (TBA)2[V3W3O 16 (CH2O)3CNHCOC 27 H 23 N2O5] raw material, 5 - 10 mL of acetonitrile and 5 - 10 mL of purified water need to be added.

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