Quadrivalent platinum rhein conjugate and application thereof in preparation of anti-cancer drugs

Abstract

The invention belongs to the technical field of biological medicine, and particularly discloses a tetravalent platinum rhein conjugate and application of the tetravalent platinum rhein conjugate in preparation of anti-cancer drugs, and the tetravalent platinum rhein conjugate has a structure as shown in a formula I or a formula II. Pharmacodynamic experiments show that compared with existing platinum drugs, rheinic acid, combined drugs of the platinum drugs and the rheinic acid and structural analogues, the tetravalent platinum rheinic acid conjugate disclosed by the invention shows unexpected ultra-strong inhibitory activity in order of magnitude on various solid tumor cells, especially on human pancreatic cancer cells MIAPaca-2. Animal in-vivo experiments further prove that the compound has an excellent tumor inhibition effect and good safety. The invention provides a candidate compound with great potential for developing a new generation of high-efficiency and low-toxicity anti-cancer drug, especially an anti-pancreatic cancer drug.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology, specifically relating to a tetravalent platinum rhein conjugate and its application in the preparation of anticancer drugs. Background Technology

[0002] Pancreatic cancer is a highly malignant digestive system tumor with insidious onset, rapid progression, and extremely poor prognosis, with a 5-year survival rate of less than 10%. It is one of the most challenging cancers to treat clinically. Platinum-based chemotherapy drugs, represented by cisplatin, are first-line drugs for treating various solid tumors, but their monotherapy efficacy in pancreatic cancer is limited, and they are often accompanied by severe toxic side effects and drug resistance.

[0003] Rhein is a key active ingredient derived from traditional Chinese medicinal herbs such as Rheum palmatum and Polygonum cuspidatum, and belongs to the anthraquinone class of compounds. Studies have shown that it possesses various biological activities, including anti-inflammatory, antioxidant, and anticancer effects, and has demonstrated potential in the treatment of pancreatic cancer.

[0004] To improve the efficacy and reduce the toxicity of platinum-based chemotherapy drugs, researchers have explored various strategies. One approach is combination therapy, such as combining platinum-based drugs with other natural products possessing anticancer activity (e.g., rhein). However, simple physical mixing often fails to produce a synergistic effect where "1+1>2," and the different pharmacokinetic behaviors of the two drugs in vivo make it difficult to ensure simultaneous delivery to the tumor site. Another approach involves constructing prodrug conjugates, linking two active molecules into a single entity via chemical bonds.

[0005] In recent years, there have been some reports on tetravalent platinum-rheic acid couplings. For example, literature ( Dalton Trans., A symmetrical compound (denoted as CP_2R) coupled with two molecules of rhein (2020, 49: 1613-1619) was reported. (Reference: [link to literature]) Dalton Trans., (2022, 51: 6014-6026) reported an asymmetric compound (denoted CPR_Ac) coupled with one molecule of rhein and one molecule of acetic acid. However, data on the anti-pancreatic cancer activity of these known conjugates are limited, and their activity has not shown any breakthrough advantages.

[0006] In summary, although attempts have been made to couple platinum with rhein, existing technologies have failed to provide a novel compound that exhibits significantly superior therapeutic effects against solid tumors such as pancreatic cancer compared to existing drugs and known analogues. Therefore, there is an urgent need in the art for a novel platinum-rhein conjugate with truly potent anticancer activity, particularly strong antipancreatic cancer activity. Based on the above, this invention proposes a tetravalent platinum-rhein conjugate and its application in the preparation of anticancer drugs. Summary of the Invention

[0007] To address the problem that while there have been attempts to couple platinum with rhein in the prior art, no novel compound has been found that demonstrates significantly superior therapeutic effects against solid tumors such as pancreatic cancer compared to existing drugs and known analogues, this invention proposes a tetravalent platinum-rhein conjugate and its application in the preparation of anticancer drugs.

[0008] In a first aspect, the present invention provides a tetravalent platinum rhein coupling compound, which adopts the following technical solution: A tetravalent platinum rhein coupling compound having the structure shown in Formula I or Formula II: .

[0009] Preferably, the tetravalent platinum rhein coupling compound is prepared by the following method: S1. Oxidize the divalent platinum drug with H2O2 to obtain an oxidation intermediate; S2. Under an inert atmosphere, the oxidized intermediate and rhein react in a solvent in the presence of a condensing agent and an organic base, and after separation and purification, a tetravalent platinum rhein conjugate is obtained.

[0010] Preferably, the divalent platinum drug in step S1 is oxaliplatin or cisplatin.

[0011] Preferably, in step S1, the mass ratio of divalent platinum drug to H2O2 is 1:15-25.

[0012] Preferably, the oxidation temperature in step S1 is 60-75℃, and the oxidation time is 5-12h.

[0013] Preferably, the condensing agent in step S2 is O-(benzotriazol-1-yl)-N,N,N',N'-tetramethylurea tetrafluoroborate (TBTU).

[0014] Preferably, the organic base in step S2 is triethylamine.

[0015] Preferably, the solvent in step S2 is N,N-dimethylformamide or dimethyl sulfoxide.

[0016] Preferably, the reaction temperature in step S2 is 10-40℃ and the reaction time is 12-48h.

[0017] Preferably, the molar ratio of the oxidized intermediate to rhein in step S2 is 1:1.2-1.8.

[0018] Preferably, the molar ratio of the oxidized intermediate to triethylamine in step S2 is 1:1.5-2.

[0019] Preferably, the molar ratio of the oxidized intermediate to TBTU in step S2 is 1:1.5-2.

[0020] Preferably, the separation and purification step in step S2 is as follows: precipitate the reaction solution with diethyl ether, filter and collect precipitate I; dissolve precipitate I in saturated sodium bicarbonate solution and wash, filter and collect precipitate II; perform silica gel column chromatography on precipitate II to obtain the target product.

[0021] Preferably, the separation and purification step in step S2 is as follows: 5-6 times the volume of diethyl ether is added to the reaction solution and stirred, precipitate I is collected by filtration, precipitate I is added to 2 times the volume of saturated NaHCO3 solution of the reaction solution and stirred, filtered, washed with water, and precipitate II is collected; precipitate II is subjected to silica gel column chromatography with a mixture of dichloromethane and methanol as the eluent, and the eluent is removed to obtain the target product.

[0022] Preferably, in step S2, the volume ratio of dichloromethane (DCM) to methanol (MeOH) in the eluent for obtaining the target product as compound I is 20:1; and the volume ratio of dichloromethane (DCM) to methanol (MeOH) in the eluent for obtaining the target product as compound II is 30:1.

[0023] Secondly, this invention provides an application of a tetravalent platinum rhein coupling compound, employing the following technical solution: Application of a tetravalent platinum rhein conjugate in the preparation of anticancer drugs.

[0024] Preferably, the anticancer drug is an anti-solid tumor drug.

[0025] Preferably, the solid tumor is pancreatic cancer, lung cancer, breast cancer, or colon cancer.

[0026] Preferably, the solid tumor is pancreatic cancer.

[0027] Preferably, the anticancer drug further includes pharmaceutically acceptable excipients.

[0028] Preferably, the excipient is a carrier, solvent, and / or excipient.

[0029] Preferably, the dosage form of the anticancer drug is an injection, tablet, capsule, or powder for injection.

[0030] In summary, the present invention has the following beneficial effects: 1. The half-maximal inhibitory concentration (IC50) of compound (CPR) of formula (II) provided by this invention against human pancreatic cancer cells MIA Paca-2 is... 50 The concentration was 1.74 µM, significantly lower than that of its parent drug cisplatin (IC50). 50 =8.28µM) and a simple physical mixture of cisplatin and rhein (IC50, 8.28µM) and cisplatin with rhein (IC50, 8.28µM). 50=8.32µM), demonstrating a significant synergistic effect of "1+1>2".

[0031] 2. Compared with the structurally closest analogue reported in the prior art, the anti-pancreatic cancer activity (IC50) of the compound of formula (II) (CPR) of the present invention is significantly greater. 50 =1.74µM) compared to the symmetrical disubstituted CP_2R (IC 50 =39.10µM) is about 22 times higher than that of the asymmetric acetic acid-substituted CPR_Ac (IC) 50 =18.8µM) is about 10 times higher.

[0032] 3. The compound group of formula (II) (CPR) provided by this invention achieved a tumor inhibition rate of up to 75% in a mouse model of pancreatic cancer xenografts, which is significantly superior to the tumor growth inhibition rates of cisplatin (CP), rhein, cisplatin + rhein (CP+R), oxaliplatin (OP), oxaliplatin + rhein (OP+R), and oxaliplatin-rhein conjugate (OPR). Furthermore, no significant systemic toxicity was observed during treatment, demonstrating good biocompatibility. Attached Figure Description

[0033] Figure 1 For the OPR in Embodiment 1 of the present invention 1 H NMR spectrum (d6-DMSO); Figure 2 For the OPR in Embodiment 1 of the present invention 13 C{ 1 H} NMR spectrum (d6-DMSO); Figure 3 For the OPR in Embodiment 1 of the present invention 195 Pt NMR spectrum (d6-DMSO); Figure 4 This is a high-resolution mass spectrum of OPR in Example 1 of the present invention; Figure 5 For CPR in Embodiment 2 of the present invention 1 H NMR spectrum (d6-DMSO); Figure 6 For CPR in Embodiment 2 of the present invention 13 C{ 1 H} NMR spectrum (d6-DMSO); Figure 7 For CPR in Embodiment 2 of the present invention 195 Pt NMR spectrum (d6-DMSO); Figure 8 This is a high-resolution mass spectrum of CPR in Example 2 of the present invention; Figure 9This is a quantitative analysis of reactive oxygen species (ROS) levels in MIA paca-2 cells from different treatment groups; Figure 10 This is a representative distribution map of MIA paca-2 cells in different treatment groups under different cell states; Figure 11 This is a distribution of cell cycle numbers in MIA paca-2 cells from different treatment groups; Figure 12 This is a graph showing the changes in tumor volume in C57BL / 6 tumor-bearing mice after treatment with different drugs; Figure 13 This is a comparison of tumors in C57BL / 6 tumor-bearing mice after treatment with different drugs. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments.

[0035] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0036] Example 1: Preparation of Oxaliplatin-Rhein Conjugate (OPR) S1, Preparation of Oxaliplatin Oxide S1, Preparation of Oxaliplatin Oxide Hydrogen peroxide (30 wt%, 18 mL) was slowly added dropwise to oxaliplatin (300 mg) over 30 minutes. The reaction system was heated to 75 °C and magnetically stirred at 400 rpm for 5 hours. After the reaction was complete, the reaction solution was cooled to room temperature (25 °C). Using a rotary evaporator, the reaction solution was concentrated to 5 mL under reduced pressure at a water bath temperature of 45 °C and a vacuum degree of -0.09 MPa. 30 mL of anhydrous ethanol was added to the concentrated solution, and a white precipitate was formed. The precipitate was collected by vacuum filtration, and the white solid product was dried in a vacuum drying oven at 40 °C to constant weight to obtain oxaliplatin oxide (212 mg, yield 65%).

[0037] Synthesis of S2, Oxaliplatin-Rhein Conjugate (OPR) Under a nitrogen atmosphere, 150 mg of oxaliplatin oxide prepared in S1 was dissolved in 5 mL of N,N-dimethylformamide (DMF), and rhein (148.3 mg), O-(benzotriazol-1-yl)-N,N,N',N'-tetramethylurea tetrafluoroborate (TBTU, 223.4 mg), and triethylamine (NEt3, 97 μL) were added. The mixture was magnetically stirred at 500 rpm for 48 h at room temperature (25 °C). After the reaction was complete, 30 mL of diethyl ether was added to the reaction solution, and stirring was continued for 5 min to allow the product to precipitate completely. The product was collected by vacuum filtration and the brownish-black solid was collected. The brownish-black solid was dissolved in 10 mL of saturated NaHCO3 solution and washed with magnetic stirring for 15 min, at which point the system became a wine-red suspension. The product was then filtered under reduced pressure, and the filter cake was washed three times with deionized water to obtain a brownish-yellow powder as the crude product. The crude product was dried in a vacuum drying oven at 40℃ for 4 hours, and then purified by silica gel column chromatography (stationary phase: 200-300 mesh silica gel; eluent: DCM:MeOH = 20:1, v / v). The target product fraction was collected, and after removing the eluent by rotary evaporation, it was dried in a vacuum drying oven at 40℃ to constant weight to obtain a yellow solid product OPR (102 mg, yield 42%).

[0038] The product 1 H, 13 C 195 Pt NMR and high-resolution mass spectrometry, such as Figure 1-4 As shown, the results indicate that the structure of the product is: This is consistent with the expected results of the synthetic route.

[0039] Example 2 Preparation of cisplatin-rheic acid conjugate (CPR) S1, Preparation of cisplatin oxide Hydrogen peroxide (30 wt%, 15 mL) was slowly added dropwise to cisplatin (250 mg) over a period of 30 minutes. The reaction mixture was heated to 60 °C and magnetically stirred at 400 rpm for 12 hours. After the reaction was complete, the reaction solution was cooled to room temperature, and a pale yellow solid precipitated. The solid was filtered under reduced pressure, washed three times with cold water at 4 °C, and the pale yellow solid product was collected and dried in a vacuum drying oven at 40 °C to constant weight to obtain cisplatin oxide (156 mg, yield 56%).

[0040] Synthesis of S2, cisplatin-rheic acid conjugate (CPR) Under a nitrogen atmosphere, 100 mg of cisplatin oxide prepared in S1 was dissolved in 5 mL of dimethyl sulfoxide. Rhein (127.6 mg), O-(benzotriazol-1-yl)-N,N,N',N'-tetramethylurea tetrafluoroborate (TBTU, 192.2 mg), and triethylamine (NEt3, 83 μL) were added. The mixture was magnetically stirred at 500 rpm for 12 h at room temperature (25 °C). After the reaction was complete, 30 mL of diethyl ether was added to the reaction solution, and stirring was continued for 5 min to allow the product to precipitate completely. The product was collected by vacuum filtration and was a brownish-black solid. The brownish-black solid was dissolved in 10 mL of saturated NaHCO3 solution and washed with magnetic stirring for 15 min, resulting in a wine-red suspension. The product was then filtered under reduced pressure, and the filter cake was washed three times with deionized water to obtain a brownish-yellow powder as the crude product. The crude product was dried in a vacuum drying oven at 40℃ for 4 hours, and then purified by silica gel column chromatography (stationary phase: 200-300 mesh silica gel; eluent: DCM:MeOH = 30:1, v / v). The target product fraction was collected, and after removing the eluent by rotary evaporator, it was dried in a vacuum drying oven at 40℃ to constant weight to obtain a yellow solid product CPR (83 mg, yield 45%).

[0041] The product 1 H, 13 C 195 Pt NMR and high-resolution mass spectrometry, such as Figure 5-8 As shown, the results indicate that the structure of the product is: This is consistent with the expected results of the synthetic route.

[0042] To verify the overall performance of the tetravalent platinum rhein coupling compound provided by this invention, comparative examples 1-7 were set up, wherein: Comparative Example 1: Single cisplatin (CP).

[0043] Comparative Example 2: Oxaliplatin (OP) alone.

[0044] Comparative Example 3: Rhein alone.

[0045] Comparative Example 4: Cisplatin + Rhein (CP+R) physical mixture (mixed at a molar ratio of 1:1).

[0046] Comparative Example 5: Oxaliplatin + Rhein (OP+R) physical mixture (mixed at a molar ratio of 1:1).

[0047] Comparative Example 6: Compound CP_2R (Reference) Dalton Trans., (Prepared in 2020, 49: 1613-1619), the specific structure is as follows: .

[0048] Comparative Example 7: Compound CPR_Ac (Reference) Dalton Trans., (Prepared in 2022, 51: 6014-6026), the specific structure is as follows: .

[0049] The comprehensive therapeutic effects of the tetravalent platinum rhein conjugates prepared in Examples 1-2 and Comparative Examples 1-7 of this invention were tested respectively.

[0050] I. In vitro activity of oxaliplatin-rhein conjugate (OPR) and cisplatin-rhein conjugate (CPR) 1. In vitro activity against pancreatic cancer cells The in vitro cytotoxicity of each compound against the human pancreatic cancer cell line MIA Paca-2 was detected using the CCK8 assay. Cells were cultured at 5 × 10⁶ cells / year. 3 Cells were seeded at a density of 100 cells / well in 96-well plates and cultured at 37°C with 5% CO2 for 24 hours. Then, a series of serially diluted concentrations of the test drug (starting from a maximum concentration of 50 µM, with 2-fold serial dilutions, resulting in 6 concentration points: 50, 25, 12.5, 6.25, 3.125, and 1.56 µM) were added. After 48 hours of further culture, the absorbance of each well at 450 nm was measured using a microplate reader, and a dose-response curve was fitted using GraphPad Prism software to calculate the half-maximal inhibitory concentration (IC50). 50 The values ​​are shown in Table 1.

[0051] Table 1. IC50 of each compound in Examples 1-2 and Comparative Examples 1-7 on MIA Paca-2 cells 50 value As shown in Table 1, the cytotoxicity of oxaliplatin-rhein conjugate (OPR) was lower than that of oxaliplatin or the combination of oxaliplatin and rhein, indicating that the killing ability of oxaliplatin against pancreatic cancer cells is reduced after the formation of conjugates with rhein. The cytotoxicity of cisplatin-rhein conjugate (CPR) was significantly higher than that of cisplatin and the combination of cisplatin and rhein (CP+R). In addition, we tested the cytotoxicity of cisplatin conjugate with two molecules of rhein (CP_2R) and cisplatin conjugate with rhein and acetate (CPR_Ac) reported in the literature. Dalton Trans, 2020, 49: 1613-1619; Dalton Trans., 2022, 51: 6014-6026), the results showed that CPR had cytotoxicity (IC50). 50 =1.74µM) is significantly stronger than CP_2R (IC) 50The cytotoxicity was 39.10 µM. These experiments demonstrate that, compared to traditional divalent platinum drugs, the tetravalent platinum compound CPR exhibits stronger bioactivity against pancreatic cancer.

[0052] 2. Research on the mechanism of action (1) Reactive oxygen species damage Platinum conjugates can generate reactive oxygen species (ROS) that damage DNA. The ROS levels in MIA paca-2 cells in the presence of CPR were assessed. MIA paca-2 cells in logarithmic growth phase were seeded into culture plates and divided into a control group (no CPR treatment) and groups treated with different concentrations of CPR (based on IC50). 50 The concentrations were set at 1.25 µM for the low-dose group and 2.5 µM for the high-dose group. After culturing in a 37°C, 5% CO2 incubator for 24 h, cells from each group (including suspension cells and adherent cells; adherent cells were digested with trypsin) were collected, washed twice with pre-cooled PBS, and the cell concentration was adjusted to 1 × 10⁻⁶. 6 Cells / mL.

[0053] Add the ROS-specific fluorescent probe DCFH-DA (final concentration 10 μM) to the cell suspension and incubate at 37°C in the dark for 20 min to allow the probe to enter the cells and be converted into non-fluorescent DCFH by intracellular esterase. After incubation, wash the cells twice with pre-cooled PBS to remove unbound probes and avoid interference with detection.

[0054] The stained cell suspension was filtered through a 400-mesh sieve to remove impurities and then analyzed using flow cytometry. Fluorescence intensity of the FITC channel (emission wavelength 525 nm) was measured using a 488 nm laser as excitation light, with at least 1 × 10⁻⁶ cells detected per group. 4 Data was recorded for each cell group. The distribution of FITC-H fluorescence intensity in each group was analyzed using the software built into the flow cytometer, and histograms were generated (X-axis for fluorescence intensity, Y-axis for cell number) to visually demonstrate the difference in intracellular ROS levels between the control group and the CPR-treated group.

[0055] The results are as follows Figure 9 As shown, compared with cisplatin (CP) or rhein, CPR can significantly induce an increase in ROS levels, suggesting that CPR-induced ROS may lead to DNA damage.

[0056] (2) Apoptosis MIA paca-2 cells were loaded at 2×10 5Cells were seeded at a density of 100 cells / well in 6-well plates and cultured for 24 h. Then, 5 μM rhein, 2.5 μM cisplatin (CP), and 2.5 μM cisplatin-rhein conjugate (CPR) were added and incubated for 48 h. The control (Ctrl) was prepared by adding an equal amount of solvent. The cells were then stained with annexin V-FITC and propidium iodide (PI) and then analyzed by flow cytometry.

[0057] The results are as follows Figure 10 As shown, at a concentration of 2.5 μM, CPR induced early and late apoptosis in 5.27% and 10.91% of MIApaca-2 cells, respectively, thus confirming its pro-apoptotic ability. In contrast, cisplatin (CP) and rhein induced little or no apoptosis at the corresponding concentrations. The stronger pro-apoptotic activity of CPR is consistent with its higher cytotoxicity.

[0058] (3) Effects on the cell cycle MIA paca-2 cells were loaded at 2×10 5 Cells were seeded at a density of 100 cells / well in 6-well plates and cultured for 24 h. Then, the cells were co-incubated for 12 h with 5 μM rhein, 2.5 μM cisplatin (CP), and 2.5 μM cisplatin-rhein conjugate (CPR), respectively. Cells with an equal amount of solvent were used as a control (Ctrl). Cell cycle experiments were then performed. Cells in the logarithmic growth phase were seeded into culture plates and treated according to the experimental design (e.g., drug intervention) and cultured for the set time. Cells were digested with trypsin, centrifuged (approximately 1000 rpm, 5 min), and washed twice with PBS to remove residual culture medium. Pre-chilled 70% ethanol was added, and cells were fixed overnight (or at least 2 h) at 4°C. The fixative was removed by centrifugation, and after washing with PBS, RNase A solution (final concentration approximately 50 μg / mL) was added, and the cells were incubated at 37°C for 30 min to remove RNA interference. Propidium iodide (PI) staining solution (final concentration approximately 50 μg / mL) was added, and the cells were incubated in the dark for 22 min. Cell fluorescence intensity was detected by flow cytometry, and the proportion of cells in each cell cycle phase (G0 / G1, S, G2 / M phases) was analyzed using FlowJo software to create a cell cycle distribution chart.

[0059] The results are as follows Figure 11 As shown, CPR primarily arrested the cell cycle of MIA paca-2 cells at the G2 / M phase. Treatment with 2.5 μM CPR increased the proportion of cells in the G2 / M phase from 28.4% to 69.3%, indicating that its main effect on the cell cycle is to inhibit the transition from G2 to M phase (mitosis). Cisplatin (CP) or rhein had a much weaker effect on the G2 / M phase than CPR.

[0060] 3. In vitro activity against other cancer cells Based on the significant anti-pancreatic cancer activity of cisplatin-rhein conjugate (CPR), the inhibitory effects of CPR on different tumor cell lines were further tested. The inhibitory effects of CPR on lung cancer A549 cell line, breast cancer MDA-MB-231 cell line, liver cancer HepG2 and Huh7 cell lines, and colon cancer HCT116 cell line were tested.

[0061] Table 2. IC50 of CPR on different cancer cell lines 50 Value (µM) Table 2 shows that, compared to the combination of cisplatin (CP) and cisplatin-rhein (CP+R), CPR significantly inhibited lung cancer, breast cancer, and colon cancer cells. However, CPR's inhibitory effect on liver cancer cells was not as strong as that of cisplatin, indicating that CPR has a certain degree of selectivity for different cancer cell types.

[0062] II. In vivo activities of oxaliplatin-rhein conjugate (OPR) and cisplatin-rhein conjugate (CPR) 1. Model Establishment A 6-8 week old C57BL / 6J allogeneic xenograft model carrying unilateral Panc02 mouse pancreatic ductal adenocarcinoma was selected. Male mice were subcutaneously inoculated with 1×10⁻⁶ cells / mL of the xenograft. 6 After 1 Panc02 cell, 350-400 mm of cells were formed within 21 days. 3 The tumor.

[0063] 2. Dosing regimen Mice were randomly divided into 8 treatment groups (n=5 per group), each receiving corn oil, cisplatin (CP), rhein, cisplatin + rhein (CP+R), cisplatin-rhein conjugate (CPR), oxaliplatin (OP), oxaliplatin + rhein (OP+R), and oxaliplatin-rhein conjugate (OPR), respectively. The dosage was determined based on mouse body weight at 4.5 mg Pt / kg, and the rhein dosage was 10.0 mg / kg, maintaining consistent drug concentrations across all groups. Administered via intraperitoneal injection, every 3 days for a total of 5 injections on days 0, 3, 6, 9, and 12.

[0064] 3. Tumor volume measurement The size of the tumor is measured using vernier calipers, and the formula is: "Tumor volume = 0.5 × L × W". 2 The volume was calculated using the formula (L: tumor length; W: tumor width). No significant weight fluctuations were observed during the study period, and tumor growth curves were plotted. At the end of the experiment, mice were euthanized by cervical dislocation, and the tumors were removed and weighed.

[0065] 4. Side effect monitoring Mouse weight changes were recorded weekly (to assess overall toxicity); mouse mental state, diet, water intake, and activity were observed after administration; at the experimental endpoint, mouse heart, liver, and kidney tissues were collected, HE staining was performed to observe pathological changes, and serum alanine aminotransferase (ALT) and serum creatinine (Scr) were measured to assess liver and kidney damage.

[0066] Tumor volume monitoring results as follows Figure 12 and Figure 13 As shown, cisplatin-rhein conjugate (CPR) was the most effective drug, achieving near-complete growth inhibition and ultimately reducing tumor weight by 75%. In comparison, cisplatin (CP), rhein, cisplatin + rhein (CP+R), oxaliplatin (OP), oxaliplatin + rhein (OP+R), and oxaliplatin-rhein conjugate (OPR) showed tumor growth inhibition rates of 35%, 33%, 42%, 44%, 58%, and 55%, respectively. Furthermore, histopathological analysis of major organs such as the heart, liver, spleen, lungs, and kidneys revealed no treatment-related abnormalities, indicating that the drug has low systemic toxicity and good biocompatibility.

[0067] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. Application of a tetravalent platinum rhein conjugate in the preparation of anticancer drugs.

2. The application of the tetravalent platinum rhein coupling compound according to claim 1 in the preparation of anticancer drugs, characterized in that, The tetravalent platinum rhein coupling compound has the structure shown in Formula I or Formula II: .

3. The application of the tetravalent platinum rhein coupling compound according to claim 1 in the preparation of anticancer drugs, characterized in that, The anticancer drug mentioned is an anti-solid tumor drug.

4. The application of the tetravalent platinum rhein coupling compound according to claim 3 in the preparation of anticancer drugs, characterized in that, The solid tumor is pancreatic cancer, lung cancer, breast cancer, or colon cancer.

5. The application of the tetravalent platinum rhein coupling compound according to claim 4 in the preparation of anticancer drugs, characterized in that, The solid tumor was pancreatic cancer.

6. The application of the tetravalent platinum rhein coupling compound according to claim 3 in the preparation of anticancer drugs, characterized in that, The anticancer drug also contains pharmaceutically acceptable excipients.

7. The application of the tetravalent platinum rhein coupling compound according to claim 6 in the preparation of anticancer drugs, characterized in that, The excipients are carriers, solvents and / or excipients.

8. The application of the tetravalent platinum rhein coupling compound according to claim 3 in the preparation of anticancer drugs, characterized in that, The dosage form of the anticancer drug is injection, tablet, capsule, or powder for injection.

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