A naphthalimide guanidine derivative, its preparation method and application

Abstract

The present invention discloses a naphthalimide guanidine derivative, a preparation method thereof and an application thereof. The structural formula of the naphthalimide acyl guanidine compound is shown as formula (I), denoted as CAUZL-C; in formula (I), R is halogen, hydrogen, piperidyl or dimethylamino; n is 1, 2, 3 or 4. The naphthalimide guanidine derivative or a pharmaceutically acceptable salt thereof according to the present invention has good target enzyme inhibitory activity and insecticidal activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural pest control, and particularly relates to a naphthalimide guanidine derivative, a preparation method thereof and an application thereof. Background Art

[0002] Chitin-degrading enzymes are key metabolic enzymes essential for the growth and development of insects. Inhibiting the function of chitin-degrading enzymes will affect the normal growth of insects and ultimately lead to death. In the agricultural pest Asian corn borer (Ostrinia furnacalis), chitin-degrading enzymes are mainly divided into chitinase OfChtI, OfChih and β-N-acetylhexosaminidase OfHex1, which play crucial roles in the chitin degradation process of the corn borer, can degrade the old cuticle of the corn borer, and promote molting and metamorphosis of the insects. Therefore, designing new pesticide insecticides targeting chitin-degrading enzymes is a potential pest control strategy. Summary of the Invention

[0003] The object of the present invention is to provide a novel naphthalimide acylguanidine compound containing naphthalimide and acylguanidine structures or a pharmaceutically acceptable salt thereof and a preparation method thereof. The naphthalimide acylguanidine compound or the pharmaceutically acceptable salt thereof according to the present invention has good target enzyme inhibitory activity and insecticidal activity.

[0004] In order to discover novel, highly efficient and low-toxic insecticides, the inventors targeted the chitin-degrading enzymes of Asian corn borer (Ostrinia furnacalis), used glycosyl carbon-glycoside naphthalimide as a lead, replaced the carbon-glycoside fragment with N-methylcarbamoylguanidine to enhance the binding of the compound to the chitin-degrading enzyme-1 site, and designed and synthesized a series of naphthalimide guanidine compounds by changing the length of the connecting chain between N-methylcarbamoylguanidine and naphthalimide to make the binding between the enzyme and the inhibitor tighter.

[0005] According to the first aspect of the present invention, there is provided a naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof, and the structural formula of the naphthalimide acylguanidine compound is shown in formula (I), denoted as CAUZL-C;

[0006]

[0007] In formula (I), R is halogen, hydrogen, piperidinyl or dimethylamino; n is 1, 2, 3, 4.

[0008] Specifically, the preparation method of the compound CAUZL-C shown in formula (I) includes the following steps:

[0009] (1) Protect the compound shown in formula (II) with Boc and react it with methylcarbamoyl chloride to obtain the compound shown in formula (III);

[0010]

[0011] (2) The compound shown in formula (III) and the compound shown in formula (IV) are reacted at room temperature in a tetrahydrofuran solution and then deprotected with trifluoroacetic acid to obtain the compound shown in formula (I).

[0012] According to the second aspect of the present invention, there is provided an application of the naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof according to the first aspect of the present invention in the preparation of an inhibitor of the chitin degrading enzyme of the Asian corn borer.

[0013] According to the third aspect of the present invention, there is provided an insecticide, the active ingredient of which is the naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof according to the first aspect of the present invention.

[0014] Specifically, the dosage form of the insecticide is a pharmaceutically acceptable dosage form; the dosage form is an emulsifiable concentrate, a suspension concentrate, a powder, an aqueous solution, a smoke agent or a seed coating agent.

[0015] For example, an emulsifiable concentrate of an insecticide is composed of the following substances in mass percentage: 1-10% of the above naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof, 5-15% of an emulsifier, 0.1-1% of a penetrant, and the balance is a solvent. The emulsifier is a surfactant, such as agricultural emulsion 0203B, 0208, GFC, OP-10, Tween-60, etc. The solvent can be toluene, xylene, etc.

[0016] For example, a wettable powder of an insecticide is composed of the following substances in mass percentage: 15-50% of the above naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof, 10-20% of a surfactant (such as surfactant NNO), and 30-75% of white carbon black.

[0017] The beneficial effects of the present invention are as follows: Taking the chitin degrading enzyme of the Asian corn borer as a biological target, the present invention discovers a variety of naphthalimide acylguanidine compounds with high inhibitory activity against the chitin degrading enzyme of the Asian corn borer. The naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof described in the present invention has good target enzyme inhibitory activity and insecticidal activity, the inhibitory activity against a variety of chitin degrading enzymes reaches the nanomolar level, has significant insecticidal activity against Plutella xylostella, significantly inhibits the growth and development of the Asian corn borer at low concentrations, and is superior to the control agent diflubenzuron. The compounds described in the present invention provide important research value for the discovery of green, highly efficient and highly specific pesticides. Description of the Drawings

[0018] Figure 1 1H NMR spectrum of compound CAUZL-C-01.

[0019] Figure 2 It is the carbon-13 NMR spectrum of compound CAUZL-C-01. Detailed implementation manners

[0020] The present invention will be described below through specific examples. It should be noted that the descriptions and examples given here are only for describing the specific implementation manners of the present invention to make it easier for those skilled in the art to understand the present invention, and they are not intended to limit the scope of the present invention.

[0021] In the following examples, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0022] Example 1 Preparation and structure identification of compound CAUZL-C-01, where R = H and n = 2.

[0023]

[0024] Add S-methylisothiourea hemisulfate (1, 1.5 mmol) to a 500 mL round-bottom flask containing 50 mL of pure water, and slowly drip 50 mL of tetrahydrofuran containing Boc anhydride (2, 4 mmol) into it, and stir overnight at 0 °C. After the tetrahydrofuran in the solution is evaporated to dryness, add 50 mL of dichloromethane (DCM) and extract three times. Collect the organic phase, wash the organic phase with water and brine, dry it over Na2SO4 and concentrate. The residue is purified by silica gel column chromatography and eluted with a gradient of petroleum ether / ethyl acetate = 50 / 1 to obtain Boc-protected S-methylisothiourea (3) with a yield of 71.2%.

[0025] At 0 °C, dissolve methylcarbamyl chloride (1 mmol) and triethylamine (1.2 mmol) in DCM (50 mL) containing Boc-protected S-methylisothiourea (3), and gradually warm to room temperature, and continue to stir the reaction for 2 h. After the reaction is completed, the solution is washed with water and brine respectively, the organic phase is collected, combined, dried over Na2SO4 and concentrated. The concentrated oily substance is purified by column chromatography and eluted with a gradient of petroleum ether / ethyl acetate = 10 / 1 to obtain compound intermediate 4.

[0026] Dissolve 1,8-naphthalic anhydride (5, 30 mmol) and propylenediamine (6, 33 mmol) in EtOH (200 mL), heat to reflux in a 500 mL round-bottom flask for 3 hours, and confirm the completion of the reaction by TLC (5:1 petroleum ether / ethyl acetate). Cool the mixture to room temperature, then filter, dry and recrystallize from ethanol to obtain intermediate 7.

[0027] Intermediate 4 (10 mM), Intermediate 7 (10 mM) and Et3N (15 mM) were dissolved in 20 mL of tetrahydrofuran, and the mixture was stirred at room temperature for 5 hours. After the reaction was completed, the mixture was concentrated by rotary evaporation, and 10 mL of dichloromethane was added to dissolve it. Then, 10 mL of trifluoroacetic acid (TFA) was added dropwise, and the mixture was stirred at room temperature for 2 hours. After that, the solvent was completely removed under reduced pressure, and then co-evaporated with toluene twice. After rotary evaporation to dryness, it was extracted with saturated sodium bicarbonate solution and dichloromethane. The organic phase was collected, washed with brine, dried and concentrated. The residue was purified by silica gel column chromatography, eluted with a gradient of petroleum ether / ethyl acetate = 1 / 1 to obtain the target compound as a white solid.

[0028] All other compounds of the general formula CAUZL-C were prepared by referring to the above method. Their compound numbers, corresponding substituents, physical and chemical data are shown in Table 1.

[0029] Table 1. Numbers, substituents, physical and chemical data of some compounds in the CAUZL-C series

[0030]

[0031] Preparation of Compound CAUZL-C-01 Emulsifiable Concentrate in Example 2

[0032] 1 - 10 g of Compound CAUZL-C-01, 5 - 15 g of emulsifier, and 0.1 - 1 g of penetrant were added to a 100 mL volumetric flask, and then made up to volume with solvents such as toluene and xylene to obtain an emulsifiable concentrate with a content of 1 - 10%.

[0033] Emulsifiable concentrates of all other compounds of the general formula CAUZL-C can be prepared by referring to the above method.

[0034] Preparation of Compound CAUZL-C-01 Wettable Powder in Example 3

[0035] 15 - 50 g of Compound CAUZL-C-01, 10 - 20 g of surfactant, and 30 - 75 g of white carbon black were taken, and after mixing and grinding, a wettable powder with a content of 15 - 50% was obtained.

[0036] Wettable powders of all other compounds of the general formula CAUZL-C can be prepared by referring to the above method.

[0037] Determination of Enzyme Inhibitory Activity of Compounds of the General Formula CAUZL-C in Example 4

[0038] Enzyme inhibition activity assay method: The inhibitory activities of compounds against the β-N-acetylhexosaminidase OfHex1 and chitinases OfChtI and OfChih of the Asian corn borer were determined using p-nitrophenyl-2-acetamido-2-deoxy-β-D-glucopyranoside (pNP-β-GlcNAc) and 4-nitrophenyl N,N'-diacetyl-β-D-chitobiose glycoside [pNP-(GlcNAc)2] as test substrates, respectively. The enzyme was mixed with the enzyme activity assay buffer (20 mM NaH2PO4, pH = 6) in a 96-well plate to a final volume of 51 μL, 3 μL of different concentrations of the inhibitor was added, and incubated at room temperature for 5 min. DMSO was used as the blank control. Finally, 6 μL of 5 mM pNP-β-GlcNAc was added to initiate the reaction, incubated at 25 °C for 5 min, and 60 μL of 0.5 M sodium carbonate was added to terminate the reaction. The absorbance was measured at 405 nm. The enzyme inhibition activities of some compounds are shown in Table 2 below.

[0039] Table 2. Inhibitory activities of some compounds in the CAUZL-C series against OfHex1, OfChtI and OfChih

[0040]

[0041] Insecticidal activity assay of the compound with the general formula CAUZL-C-01 in Example 5

[0042] Assay method: The Asian corn borer and the diamondback moth were hatched and reared in a light incubator at a temperature of 27 °C and a light-dark cycle of 14 h:10 h. The insecticidal activities of the target compounds against the Asian corn borer and the diamondback moth were evaluated by the artificial diet and leaf immersion methods, respectively. 150 third-instar larvae were divided into three groups and reared in petri dishes containing treated artificial diet or leaves. The Asian corn borer was continuously fed for 120 h (the diamondback moth was fed for 72 h), and the number of surviving larvae was counted to calculate the mortality rate. If the larvae did not respond to a gentle touch with a brush tip, they were considered dead. The insecticidal activity data of some compounds are shown in Table 3.

[0043] Sources of test targets:

[0044] The diamondback moth (Plutella xylostella Linnaeus) was collected from vegetable fields in Beijing in 2023; the Asian corn borer was purchased from Henan Baiyun Biotechnology Co., Ltd.

[0045] Table 3. Insecticidal activities of some compounds in the CAUZL-C series against the diamondback moth and inhibitory activity IC 50 value

[0046]

[0047] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof, the structural formula of the naphthalimide acylguanidine compound is shown as formula (I), denoted as CAUZL-C; In formula (I), R is halogen, hydrogen, piperidinyl or dimethylamino; n is 1, 2, 3, or 4.

2. The naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof according to claim 1, the preparation method of the compound CAUZL-C shown in formula (I) comprises the following steps: (1) Protect the compound shown in formula (II) with Boc and react it with methylcarbamoyl chloride to obtain the compound shown in formula (III); (2) React the compound shown in formula (III) with the compound shown in formula (IV) at room temperature in a tetrahydrofuran solution and then deprotect with trifluoroacetic acid to obtain the compound shown in formula (I).

3. Use of the naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof according to claim 1 in the preparation of an inhibitor of the chitin degrading enzyme of the Asian corn borer.

4. An insecticide, the active ingredient of which is the naphthalimide acylguanidine compound or a pharmaceutically acceptable salt thereof according to claim 1.

5. The insecticide according to claim 4, the dosage form thereof is a pharmaceutically acceptable dosage form; the dosage form is emulsifiable concentrate, suspension concentrate, powder, aqueous solution, smoke agent or seed coating agent.

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