(Iso)quinolines having with strigolactone activity and their preparation and use

Abstract

This invention discloses (iso)quinoline compounds with strigolactone activity, their preparation, and applications. The (iso)quinoline compounds have the structural formulas shown in Formulas III-A, III-B, and III-C. This invention provides a strigolactone analog with a simple structure, convenient synthesis, and high biological activity. Simultaneously, the activity of these compounds in the seed germination of *Orobanche deserticola* and *Orobanche spp.*, the hypocotyl and root growth of *Arabidopsis thaliana*, the tillering of rice, and the growth of ryegrass were tested. The results show that these compounds have good seed germination activity against *Orobanche deserticola*, good inhibitory activity against hypocotyl and taproot growth in *Arabidopsis thaliana* and rice tillering, and moderate to high inhibitory activity against ryegrass. These compounds are easy to prepare, low in cost, and have high value for agricultural application and promotion, making them worthy of further in-depth research and development. They are plant growth regulators with broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of plant growth regulators, specifically relating to (iso)quinoline compounds with strigolactone activity and their preparation and application. Background Technology

[0002] Plant growth regulators are widely used in agricultural production to effectively regulate crop growth processes, achieving goals such as stable and increased yields, improved quality, and enhanced crop resistance. Strigolactones (SLs) are a novel class of endogenous plant hormones that have attracted considerable attention in recent years. SLs are present in many plants, especially in root exudates. The first SLs were a class of carotenoid terpene lactones isolated from cotton root exudates in 1966. Based on their structure, strigolactones are mainly divided into two categories: typical and atypical compounds. Typical SLs... S The butenolactone ring (D ring) is connected to the tricyclic lactone (ABC ring) via an enol ether bridge, an atypical SL S The ABC rings in the middle are replaced by irregular ring structures.

[0003] As a class of natural plant signaling molecules, strigolactone molecules with different structures may exhibit different biological activities. S SLS regulates the coordinated development of roots and aboveground parts, such as branching / tillering and secondary shoot growth, determining the formation of primary roots, lateral roots, crown and adventitious roots, and root hair density. Furthermore, SLS also regulates leaf senescence and root nodulation, and participates in pathogen defense and abiotic stress responses. S As a rhizosphere signaling molecule, it induces seed germination in parasitic plants by stimulating hyphal branching in arbuscular mycorrhizal fungi and establishing a beneficial symbiotic relationship with them.

[0004] Natural SL S Due to their extremely low content in plants, complex structures, and high cost of artificial synthesis, strigolactones cannot be prepared on a large scale. Therefore, designing and synthesizing highly active and structurally simple strigolactone analogs is a current research hotspot. Currently, the most widely used and effective analog is GR24, but its complex structure, cumbersome synthesis steps, and low yield lead to high production costs, limiting its large-scale promotion and use. Therefore, designing simple, inexpensive, and efficient strigolactone functional analogs is crucial. Summary of the Invention

[0005] The purpose of this invention is to provide a (iso)quinoline compound with strigolactone activity, its preparation and application. The (iso)quinoline compound of this invention plays an important role in plant growth regulation and can be used as a plant growth regulator in agriculture.

[0006] The (iso)quinoline compounds provided by this invention have the structural formulas shown in Formula III-A, Formula III-B, and Formula III-C:

[0007]

[0008] In formulas III-A, III-B, and III-C,

[0009] R represents a substituent on the (iso)quinoline ring, selected from at least one of hydrogen, halogen, and hydroxyl.

[0010] Specifically, R is at least one of hydrogen, fluorine, chlorine, bromine, and hydroxyl.

[0011] Specifically, the compounds represented by formulas III-A, III-B, and III-C are any one of the following compounds:

[0012]

[0013] The present invention also provides methods for preparing the compounds shown in formulas III-A, III-B, and III-C.

[0014] The method for preparing the compounds shown in formula III-A, III-B, and III-C provided by the present invention includes the following steps: in the presence of a condensing agent, the compounds shown in formula IA, formula IB, or formula IC are respectively subjected to a condensation reaction with the compound shown in formula II to obtain the compounds shown in formula III-A, III-B, and III-C respectively.

[0015]

[0016] In equations IA, IB, and IC, R is the same as R in equations III-A, III-B, and III-C.

[0017] In the above preparation method, the condensation reagent is at least one of DIC, DIEA, DCC, DMAP, EDCI, and HOBt;

[0018] In the above preparation method, the esterification condensation reaction is carried out at -10 to 60°C, preferably at room temperature, and the reaction time can be 2-24 hours, preferably 12 hours, 4-8 hours, or 8-12 hours.

[0019] The molar ratio of the compounds shown in formulas IA, IB, and IC to the compound shown in formula II can be 1:0.8 to 10, specifically 1:1.2 to 10.

[0020] In the above preparation method, the esterification condensation reaction is carried out in an organic solvent.

[0021] The organic solvent is selected from at least one or any combination of two or more of the following: cyclohexane, hexane, tetrahydrofuran, dichloromethane, 1,4-dioxane, ethyl acetate, methanol, ethanol, n-propanol, carbon tetrachloride, DMF, chloroform, diethyl ether, and acetonitrile.

[0022] In the above preparation method, the reaction product is obtained by column chromatography purification.

[0023] The applications of the compounds represented by formulas III-A, III-B, and III-C as plant growth regulators are also within the scope of protection of this invention in the following aspects:

[0024] 1) Promotes the germination of parasitic weed seeds;

[0025] 2) Inhibits the elongation of the hypocotyl in plant seedlings;

[0026] 3) Inhibits the growth of the plant's taproot;

[0027] 4) Inhibits the branching development of plants.

[0028] The plants mentioned may specifically be Arabidopsis thaliana, rice, or wheat.

[0029] The parasitic weeds mentioned may specifically be sunflower broomrape and melon broomrape.

[0030] Furthermore, the application of the compounds of formulas III-A, III-B, and III-C provided by this invention in weed control, and herbicides containing compounds of formulas III-A, III-B, and III-C, also fall within the scope of protection of this invention. Specifically, the types of grasses mentioned are ryegrass, wild oats, jointed goatgrass, barnyard grass, foxtail grass, or goatgrass;

[0031] Specifically, the application refers to the use of compounds represented by formulas III-A, III-B, and III-C in the following aspects:

[0032] 1) Promotes the germination of broomrape seeds;

[0033] 2) Inhibits the growth of the hypocotyl and the taproot of Arabidopsis thaliana;

[0034] 3) Inhibits rice tillering;

[0035] 4) Inhibits the growth of ryegrass stems and roots.

[0036] The present invention also provides a plant growth regulator containing compounds represented by formulas III-A, III-B, and III-C.

[0037] This invention designs and synthesizes a novel class of (iso)quinoline compounds with strigolactone activity. All designed compounds have novel structures and are reported for the first time.

[0038] This invention provides a strigolactone analogue with a simple structure, convenient synthesis, and high bioactivity. The activity of this compound in seed germination of *Orobanche deserticola* and *Orobanche spp.*, hypocotyl and root growth of *Arabidopsis thaliana*, tillering of rice, and growth of ryegrass was tested. The results showed that this compound exhibited good seed germination activity against *Orobanche deserticola*, good inhibitory activity against hypocotyl and taproot growth in *Arabidopsis thaliana*, and tillering in rice, and moderate to high inhibitory activity against ryegrass. This compound is easy to prepare, low in cost, and has high value for agricultural application and promotion, making it worthy of further in-depth research and development. It is a plant growth regulator with broad application prospects. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0041] Example 1: Preparation of compound III-A-01

[0042]

[0043] At room temperature, 4.82 mmol of 2-chloroquinoline-4-carboxylic acid, 5.78 mmol of DCC, and 0.24 mmol of DMAP were added to a 40 mL solution of tetrahydrofuran. The reaction was stirred for 0.5 h. Then, a 15 mL mixture of 5-hydroxy-3-methyl-2(5H)-furanone (5.78 mmol) and tetrahydrofuran was slowly added dropwise to the reaction system. The mixture was stirred overnight at room temperature, and the reaction was monitored by TLC (petroleum ether / ethyl acetate 3:1). After the reaction was complete, the reaction solution was filtered, the filtrate was extracted with dichloromethane, washed with saturated brine, dried over anhydrous sodium sulfate, concentrated the solvent, and purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 3:1, v / v) to obtain the target compound III-A-01.

[0044] By referring to the above preparation method, a series of compounds of formula III-B and III-C can be prepared.

[0045] The appearance, melting point, and yield of some of the compounds with specific formulas III-A, III-B, and III-C are listed in Table 1. 1H NMR and 13 The C NMR data are listed in Table 2.

[0046] Table 1. Appearance and yield of some compounds of formulas III-A, III-B, and III-C

[0047] III-A-01 52％ White solid III-A-02 48％ White solid III-A-03 65％ White solid III-A-04 46％ White solid III-A-05 42％ White solid III-B-01 62％ White solid III-C-01 75％ White solid

[0048] Table 2. Nuclear magnetic resonance data of some compounds of formulas III-A, III-B, and III-C 1 H NMR and 13 C NMR data

[0049]

[0050]

[0051] Example 2: The seed germination activity of compounds of formula III-A, III-B, and III-C on sunflower broomrape and cucurbita broomrape was tested using the following methods:

[0052] Sunflower broomrape seeds were surface-sterilized by soaking in 75% alcohol for 2 minutes, followed by rinsing with sterile distilled water. A 9cm diameter plastic petri dish was prepared, with two sheets of filter paper at the bottom moistened with sterile distilled water, and then covered with 10mm diameter glass fiber filter paper. Approximately 30-80 seeds were evenly sprinkled onto the moistened glass fiber filter paper. The petri dish was sealed with adhesive tape and pre-cultured in the dark at 25℃ for 7 days. The pre-cultured seeds were then placed on the glass fiber filter paper in the plastic petri dish, and 50μL of the test compound solution was added. The petri dish was sealed with adhesive tape. The seeds were then placed in a 25℃ incubator for 7 days. The germination rate of the broomrape seeds was observed and counted using a binocular microscope. Germination was considered complete when the radicle appeared. Commercially available GR24 was used as a positive control, and sterile distilled water as a negative control. Each compound concentration was tested in triplicate, with five sets of experiments per concentration, and the mean and standard deviation were calculated. The germination activity test method for cucurbita broomrape seeds was the same. The data on the germination activity of some compounds of formula III-A, III-B, and III-C on sunflower broomrape and cucurbita broomrape seeds are shown in Table 3.

[0053] Table 3. Germination rates of some compounds of formulas III-A, III-B, and III-C on sunflower broomrape and cucurbita broomrape seeds.

[0054]

[0055] As shown in Table 3, in 10 -5Under M conditions, compounds III-A-01, III-A-02, and III-A-03 exhibited good promoting activity against the germination of sunflower broomrape seeds. Among them, III-A-01 showed the best activity, achieving a germination rate of 55.8%, comparable to the control GR24 (58.2%). Simultaneously, the germination activity test results of cucurbita broomrape seeds showed that all the designed compounds possessed excellent germination-promoting activity. At 10 -6 Under M conditions, compounds III-A-01, III-B-01, and III-C-01 achieved germination rates of 96.1%, 96.6%, and 90.2% for *Trichosanthes kirilowii* seeds, respectively, comparable to GR24 (94.7%). Compound III-B-01 exhibited the best germination-promoting activity against *Trichosanthes kirilowii* seeds. These results indicate that (iso)quinoline compounds are inexpensive, and under the same conditions, these new compounds have high potential value in the development of germination promoters for parasitic weed seeds.

[0056] Example 3: Hypocotyl growth activity test and root growth test of Arabidopsis thaliana wild-type from Colombia.

[0057] Wild-type Arabidopsis seeds (Columbia-0, Col-0) were washed with 1% sodium hypochlorite for 15 min, sterile water, and sown on 1 / 2 MS media (0.8% agar, 1% sucrose, and a specified concentration of the compound). After vernalization at 4°C for 3 days, the plants were transferred to a climate chamber and cultured at 22°C in darkness for 7 days. The hypocotyl length was measured using ImageJ software after photographing the entire plant. The hypocotyl growth inhibition rate was calculated using the formula: Hypocotyl growth inhibition rate = (hypocotyl length in the control group - hypocotyl length in the drug group) / hypocotyl length in the control group × 100%. The test results for all compounds are shown in Table 4.

[0058] Arabidopsis seeds were disinfected with 1% sodium hypochlorite solution for 15 min, rinsed with sterile water, and sown on 1 / 2 MS medium (0.8% agar, 1% sucrose, and a specified concentration of compound). After vernalization at 4℃ for 3 days, the seeds were transferred to an artificial climate chamber and cultured in light and dark conditions (16 / 8h, 22 / 19℃) for 7 days. The entire plant was photographed, and the length of the taproot of Arabidopsis was measured using ImageJ software. The taproot growth inhibition rate was calculated using the formula: taproot growth inhibition rate = (taper root length of blank group - taproot length of drug group) / taproot length of blank group × 100%, as shown in Table 5.

[0059] Table 4. Inhibition rates of some compounds of formulas III-A, III-B, and III-C on the growth of Arabidopsis hypocotyls.

[0060]

[0061] Table 4 shows that the (iso)quinoline compounds involved in this invention can effectively inhibit the growth of Arabidopsis hypocotyls and exhibit high activity. At a concentration of 10 μM, compound III-A-03 showed a significant inhibitory effect of 54.9%, which is superior to GR24 (44.9%). At a concentration of 50 μM, the inhibitory effect of several compounds on Arabidopsis hypocotyl growth increased with increasing concentration, with III-A-03 achieving an inhibition rate of 78.7%.

[0062] Table 5. Inhibition rates of some compounds of formulas III-A, III-B, and III-C on the taproot growth of Arabidopsis thaliana.

[0063]

[0064] Table 5 shows that the (iso)quinoline compounds of this invention possess functions similar to strigolactones, and exhibit higher activity. According to the results in Table 5, at 10 μM, most compounds inhibited the growth of the primary root of Arabidopsis thaliana, with compound III-A-02 showing the best activity, achieving an inhibition rate of 51.2%, superior to GR24 (50.2%). At a concentration of 50 μM, the inhibitory activities of compounds III-A-03, III-A-04, and III-C-01 were comparable to those achieved by GR24 at the same concentration. The compounds involved in this invention possess strigolactone-related activities, and their design cost is low, making them more valuable under the same conditions.

[0065] Example 4: Inhibitory effects of compounds of formula III-A, III-B, and III-C on rice tillering

[0066] Rice seeds (Nipponbare) were surface-sterilized by washing with 1.5% sodium hypochlorite for 30 minutes, then thoroughly rinsed with sterile deionized water, and cultured in water at 30°C in the dark for 2 days. Pre-germinated seeds were then transferred to filter paper in 90 mm petri dishes and cultured under fluorescent white light (130–180 μm). 2 s -1 Rice seedlings were cultured at 30°C for one week, with a 16-hour light-8-hour dark cycle. Seven-day-old seedlings were then transferred to hydroponic containers containing nutrient solution and grown in an artificial climate chamber. The compounds were applied to rice at a concentration of 2 μM, with GR24 used as a positive control. These compounds were applied twice weekly for a total of six applications. The number of tillers per plant was measured at final harvest, and the results for all compounds are shown in Table 6.

[0067] Table 6. Inhibitory activities of some compounds of formulas III-A, III-B, and III-C on rice tillering.

[0068]

[0069] Table 6 shows that the compounds prepared in this invention all exhibit varying degrees of inhibitory effects on rice tillering. At a test concentration of 2 μM, compounds III-B-01 and III-C-01 showed good inhibitory effects on the growth of rice tiller shoots, with average tiller numbers of 2.7 and 2.6, respectively, comparable to GR24 (2.6 tillers). These compounds are inexpensive and have potential applications in agricultural production.

[0070] Example 5: Inhibitory effect of some compounds of formula III-A, III-B, and III-C on ryegrass growth.

[0071] First, soak ryegrass (Lolium perenne L.) seeds in water for 24 hours. Dissolve 10 mg of the compound in 1 mL of DMSO, and then prepare a 100 mg / L test solution using a 0.5% Tween 80 aqueous solution. Place germination paper in a 9 cm diameter round petri dish, add 5 mL of the test solution to the petri dish containing the filter paper, and then evenly scatter about 30 ryegrass seeds on the petri dish. Repeat each experiment three times. After sealing, place in a light incubator with conditions of 25℃ and a 16 h light / 8 h dark cycle. Observe the germination and growth of the weeds daily. After 7 days of cultivation, measure the root and stem lengths of 7-day-old seedlings. The test results for all compounds are shown in Table 7.

[0072] Table 7. Inhibitory effects of compounds on ryegrass growth at 100 mg / L

[0073]

[0074] As shown in Table 7, the compounds prepared in this invention exhibit moderate to high inhibitory effects on the stem and root growth of ryegrass. At a test concentration of 100 mg / L, compounds III-A-01, III-A-02, III-A-03, III-A-04, and III-C-01 all showed inhibitory activity exceeding 60% on both ryegrass roots and stems, with III-C-01 showing the best effect, exhibiting an inhibitory effect exceeding 80% on both roots and stems. Specifically, in inhibiting ryegrass stem growth, compound III-C-01 showed the highest inhibition rate among all target compounds, reaching 83.6%. In inhibiting the root growth of ryegrass, compounds III-A-01, III-A-02, III-A-03, III-A-05, and III-B-01 showed root inhibition rates between 60% and 80%, while III-A-04 achieved an inhibition rate of 92.7%. Among these, III-C-01 achieved a 100% root growth inhibition rate, comparable to the control herbicide acetochlor. This indicates that the (iso)quinoline compound III-C-01 in this series has significant potential in weed control and warrants further research to develop herbicides with plant hormone activity. This compound is inexpensive and has potential application value in agricultural production.

[0075] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. Any one of the following compounds: 。 2. The use of the compound of claim 1 as a plant growth regulator in the following aspects: 1) Promotes the germination of parasitic weed seeds; 2) Inhibits the elongation of the hypocotyl in plant seedlings; 3) Inhibits the growth of the plant's taproot; 4) Inhibits branching development in plants; The plants mentioned are Arabidopsis thaliana, rice, and wheat; The parasitic weeds mentioned are sunflower broomrape and melon broomrape.

3. The use of the compound of claim 1 in weed control, wherein the type of weed is ryegrass, wild oat, jointed goatgrass, barnyard grass, foxtail grass, or goatgrass.

4. A plant growth regulator comprising the compound of claim 1.

5. A herbicide comprising the compound of claim 1.

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