Camptothecin derivative as well as preparation method and application thereof

Abstract

The invention discloses a camptothecin derivative as well as a preparation method and application thereof. The camptothecin derivative has a general formula shown as a structural formula (I). Wherein R1 is one of hydrogen, amino, hydroxyl, methyl, methoxyl, nitryl, halogen and trifluoromethyl, R2 is one of hydrogen, methyl, ethyl and halogen, and R3 is one of hydrogen and acetyl. The preparation method comprises the following steps: carrying out condensation reaction on (S)-4-ethyl-4-hydroxy-7, 8-dihydro-1H-pyran O [3, 4-F] indolizine-3, 6, 10 (4H)-ketone and an o-aminobenzaldehyde / acetophenone derivative in N, N-dimethylformamide under the protection of nitrogen, and synthesizing a target compound through the catalysis of trimethylchlorosilane. The camptothecin derivative prepared by the invention has a remarkable antifungal effect, and tests prove that the camptothecin derivative has broad-spectrum inhibitory activity on various plant pathogenic fungi. According to the invention, the resistance limitation of the traditional bactericide is broken through, and an efficient and low-toxicity novel solution is provided for prevention and treatment of fungal diseases of agricultural and forestry crops.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis of antifungal drugs, and in particular to a preparation method of camptothecin derivatives and their application as highly effective inhibitors of plant pathogenic fungi. Background Art

[0002] Food and ecological security are crucial to national prosperity, people's livelihoods, and social stability, and are the cornerstones of national strategic security. Diseases caused by plant pathogenic fungi not only seriously threaten the high-quality and high-yield of crops like rice and wheat, but also pose a formidable challenge to the prevention and control of major forest diseases such as poplar bark rot and Pinus sylvestris dieback. These diseases damage plant tissue structure and physiological functions, leading to yield losses and quality degradation in agricultural and forestry crops. While modern agriculture has achieved some initial control success through the large-scale application of chemical fungicides, global direct economic losses from fungal diseases still amount to 10%-23% of crop output value each year. Forest diseases also significantly degrade ecosystem services. More critically, under the selective pressure of long-term monopharmacy in agriculture, crop pathogens such as Fusarium and forest pathogens such as Solanum sphaeroides have co-evolved multiple resistance mechanisms, resulting in a systematic decline in the control effectiveness of traditional fungicides. Therefore, the development of new plant fungal inhibitors with broad-spectrum antimicrobial activity and resistance management capabilities has become an urgent need to ensure safe agricultural and forestry production.

[0003] Camptothecin is a natural quinoline alkaloid isolated from the bark and fruit of Camptotheca acuminata. Since its discovery in 1966, its significant anti-tumor activity has been demonstrated in vitro, with potent inhibitory effects against HeLa cervical cancer cells and L1210 leukemia cell models. For nearly three decades, the development of camptothecin derivatives has focused on cancer therapy, while the compound's potential in agricultural chemistry has remained largely unexplored.

[0004] In view of the advantages of camptothecin's wide pharmacological activity and structural modifiability, an efficient and flexible synthetic method was adopted to design and optimize a new library of camptothecin derivatives, and evaluate the inhibitory activity of these derivatives against various plant pathogens and fungi. The synthesis and antifungal activity of most of these compounds were reported for the first time, breaking through the resistance barriers of traditional fungicides and achieving broad-spectrum, efficient and precise inhibition of a variety of plant pathogens. Summary of the Invention

[0005] Based on the above analysis, the first object of the present invention is to provide a camptothecin derivative having the general formula of structural formula I:

[0006] in:

[0007] R1 is one of hydrogen, amino, hydroxy, methyl, methoxy, nitro, halogen, and trifluoromethyl;

[0008] R2 is one of hydrogen, methyl, ethyl, and halogen;

[0009] R3 is one of hydrogen and acetyl;

[0010] The structure of the derivative is any one of compounds A1 to A23, B1 to B12, C1, D1 to D4 in Example 1 of the specification.

[0011] The present invention also discloses a method for preparing camptothecin, comprising the following steps:

[0012] (1) Under nitrogen protection, dissolving (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one and an o-aminoaryl carbonyl compound in N,N-dimethylformamide to obtain a first mixed liquid;

[0013] (2) adding trimethylchlorosilane dropwise to the first mixed liquid, heating the mixture for a certain period of time, monitoring the reaction endpoint by thin layer chromatography, and obtaining a reaction solution;

[0014] (3) The reaction solution was quenched with ice water, filtered, and then purified by column chromatography using a mixed solution of ethyl acetate and petroleum ether to obtain camptothecin.

[0015] Furthermore, the o-aminoaryl carbonyl compound in step (1) is selected from o-aminobenzaldehyde or o-aminoacetophenone derivatives.

[0016] Furthermore, in step (1), the molar ratio of the (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one to the o-aminoaryl carbonyl compound is 1:1-2.

[0017] Furthermore, the amount of trimethylsilyl chloride used in step (2) is 1-5 times the molar amount of (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one.

[0018] Furthermore, the temperature of the temperature-raising reaction in step (2) is 100±5° C., and the time is 3-6 hours.

[0019] Furthermore, the volume ratio of ethyl acetate to petroleum ether in step (3) is 1:5.

[0020] The present invention also discloses a camptothecin biopeptide prepared according to any of the above preparation methods.

[0021] The present invention also discloses an application of the camptothecin biomass in preparing a preparation for inhibiting or killing plant pathogenic fungi.

[0022] Furthermore, the plant pathogenic fungi include but are not limited to:

[0023] Rhizoctonia solani, Solanum solani, Rice blast pathogen, Botrytis cinerea, Conchoceras pinecone, Fusarium oxysporum or Fusarium graminearum.

[0024] The beneficial effects of the present invention are:

[0025] The present invention prepares camptothecin derivatives and applies them to resist plant pathogenic fungi. Compared with the existing technology, the derivatives synthesized by the present invention have significant inhibitory effects on Rhizoctonia solani, Aspergillus niger, rice blast pathogen, gray mold, Fusarium oxysporum, Fusarium graminearum and Aspergillus niger, achieving broad-spectrum antibacterial effect and providing a new direction for the prevention and control of plant diseases. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to specific examples. This embodiment is carried out based on the technology of the present invention, and detailed implementation methods and specific operation processes are now given to illustrate that the present invention is creative, but the scope of protection of the present invention is not limited to the following examples.

[0027] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples are all commercially available.

[0028] Example 1

[0029] Preparation of camptothecin derivatives

[0030] Preparation: Under nitrogen, dissolve (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one (131.6 mg, 0.5 mmol) and o-aminobenzaldehyde or o-aminoacetophenone (0.75 mmol) in N,N-dimethylformamide (2 mL). Add trimethylsilyl chloride (217.28 mg, 2 mmol) dropwise via syringe at room temperature. After the addition is complete, heat to 100°C and stir for 4 hours. Monitor the reaction by thin-layer chromatography. Once the starting material spots disappear, cool to room temperature. Pour the reaction mixture into ice water, filter, and wash the filter cake with anhydrous ethanol to obtain a camptothecin derivative. If this method fails to produce a pure camptothecin derivative, it can be purified by column chromatography (EA:PE = 5:1).

[0031] The specific added substrates, reaction products and yields of the o-aminobenzaldehyde or o-aminobenzophenone derivatives are shown in Table 1; the nuclear magnetic resonance characterization data and standard nomenclature of the reaction products are shown in Table 2.

[0032] Table 1

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] (-) indicates purchase income

[0041] Table 2

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049] Test Example 1

[0050] Antifungal activity test of camptothecin derivatives

[0051] Test target: target compounds A1-A23; B1-B12; C1; D1-D4 prepared in Example 1.

[0052] Test Method: Mycelial growth rate assay was used to determine the inhibitory activity of the target compound against six plant pathogenic fungi at 15 and 30 μg / mL, respectively. The test species were Rhizoctonia solani, Aspergillus pinecone, Magnaporthe grisea, Botrytis cinerea, Fusarium graminearum, and Aspergillus niger. Results: See Table 3.

[0053] The experiment conducted gradient dilution of camptothecin derivatives with excellent activity (inhibition rate higher than 50%) at a concentration of 15 μg / mL to further test the antibacterial activity, and finally calculated the EC by the toxicity regression equation. 50 Value, experimental results: as shown in Table 4.

[0054] Table 3

[0055]

[0056]

[0057] (-) means not tested

[0058] Table 4

[0059]

[0060] (-) means not tested

[0061] Results: At a concentration of 30 μg / mL, camptothecin (A1) exhibited broad-spectrum inhibitory activity against a variety of plant pathogenic fungi, with the most significant inhibitory effects against Aspergillus niger, Magnaporthe oryzae, and Aspergillus pinecone. As measured by the mycelial growth rate assay, the colony growth inhibition rates of all three pathogens reached 100%, demonstrating strong antifungal properties. However, at a concentration of 15 μg / mL, the inhibitory effect of A1 showed a significant downward trend, with inhibition rates against Rhizoctonia solani and Fusarium graminearum of only 62.8% and 69.9%, respectively. Structurally modified derivatives exhibited significant antifungal activity. Derivative A22 exhibited inhibition rates of up to 100% against Aspergillus pinecone, Magnaporthe oryzae, Botrytis cinerea, Fusarium graminearum, and Aspergillus niger at a concentration of 15 μg / mL.

[0062] Further structure-activity relationship analysis showed that structural modification has a decisive influence on the antifungal activity of the derivatives. Some derivatives can achieve strong antifungal activity at low concentrations, especially derivative A22, which has an EC of 1. 50 The value was 0.0299 μg / mL, which was significantly better than that of A1 without structural modification (EC 50 The value was 0.156 μg / mL), indicating its excellent antibacterial activity. Therefore, through structural modification, the antibacterial efficiency of the derivative at low concentrations was significantly improved, providing an important structural template and theoretical basis for the molecular design of new agricultural fungicides.

[0063] Finally, it should be noted that the above implementation cases are only used to illustrate the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred implementation cases, ordinary technicians in this field should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A camptothecin derivative, the structural formula of which is shown in formula (I): in: R1 is one of hydrogen, amino, hydroxy, methyl, methoxy, nitro, halogen, and trifluoromethyl; R2 is one of hydrogen, methyl, ethyl, and halogen; R3 is one of hydrogen and acetyl.

2. A method for preparing the camptothecin biopeptide according to claim 1, comprising the following steps: (1) Under nitrogen protection, dissolving (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one and an o-aminoaryl carbonyl compound in N,N-dimethylformamide to obtain a first mixed liquid; (2) adding trimethylchlorosilane dropwise to the first mixed liquid, heating the mixture for a certain period of time, monitoring the reaction endpoint by thin layer chromatography, and obtaining a reaction solution; (3) The reaction solution was quenched with ice water, filtered, and then purified by column chromatography using a mixed solution of ethyl acetate and petroleum ether to obtain camptothecin.

3. The preparation method according to claim 2, wherein: The o-aminoaryl carbonyl compound in step (1) is selected from o-aminobenzaldehyde or o-aminoacetophenone derivatives.

4. The preparation method according to claim 2, wherein: The molar ratio of the (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one to the o-aminoaryl carbonyl compound in step (1) is 1:1-2.

5. The preparation method according to claim 2, wherein: The amount of trimethylsilyl chloride used in step (2) is 1-5 times the molar amount of (S)-4-ethyl-4-hydroxy-7,8-dihydro-1H-pyrano[3,4-F]indolizine-3,6,10(4H)-one.

6. The preparation method according to claim 2, wherein: The temperature of the temperature-raising reaction in step (2) is 100±5° C. and the reaction time is 3-6 hours.

7. The preparation method according to claim 2, wherein: The volume ratio of ethyl acetate to petroleum ether in step (3) is 1:

5.

8. A camptothecin biopeptide obtained according to the preparation method according to any one of claims 2 to 7.

9. Use of the camptothecin according to claim 1 or 8 in preparing a preparation for inhibiting or killing plant pathogenic fungi.

10. The use according to claim 9, wherein: The plant pathogenic fungi include: Rhizoctonia solani, Solanum solani, Rice blast pathogen, Botrytis cinerea, Conchoceras pinecone, Fusarium oxysporum or Fusarium graminearum.

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