Preparation method of trigonelline inner salt and application of trigonelline inner salt in inhibition of algae growth
By improving the preparation method of trigonelline inner salt, using inexpensive and readily available ethyl nicotinate and dimethyl sulfate, the problems of high preparation cost and poor environmental performance in the existing technology are solved, realizing the effective application of trigonelline inner salt in inhibiting algal growth, with a concentration-dependent inhibition effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-21
- Publication Date
- 2026-04-07
AI Technical Summary
Existing methods for preparing trigonelline are costly, complex, and environmentally unfriendly, and there is limited research on its application in inhibiting algal growth.
The inner salt of trigonelline was obtained by reacting ethyl nicotinate with dimethyl sulfate in methanol, followed by reaction with alkali and thiourea in water, and by adjusting the pH and solvent extraction. This method avoids the use of highly toxic reagents, reduces synthesis costs, and improves the environmental friendliness of the process.
The efficient preparation of trigonelline inner salt and its application in inhibiting algal growth were achieved, demonstrating a concentration-dependent inhibitory effect, suitable for large-scale industrial production and reducing environmental risks.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of pharmaceutical technology, and in particular to a method for preparing trigonelline inner salt and its application in inhibiting algal growth. Background Technology
[0002] Fenugreek is an annual legume native to southern Europe. It was introduced to China during the Han Dynasty and is now cultivated in most provinces of northwestern my country. Fenugreek seeds are the dried, mature seeds of the fenugreek plant, rich in substances beneficial to the human body, such as steroidal saponins and alkaloids, and are included in the *Pharmacopoeia of the People's Republic of China*. Trigonelline is one of the extracts from fenugreek seeds; it is widely found in the plant, highly hydrophilic, readily soluble in polar solvents such as methanol, and insoluble in non-polar solvents such as ether.
[0003] Regarding synthetic methods, existing literature and patents primarily involve methylation using raw materials such as iodomethane or dimethyl sulfate. Iodomethane is expensive, and its toxic and volatile nature makes large-scale use difficult. Dimethyl sulfate is cheaper, but its high toxicity and the production of highly toxic byproducts such as monomethyl sulfate, coupled with the need for harsh conditions like high-temperature heating with large amounts of concentrated sulfuric acid to remove monomethyl sulfate, have made it difficult to process into production. Currently, the primary method for producing trigonelline remains extraction.
[0004] In terms of applications, fenugreek has a long history of use as food and medicine in my country and India. Consuming fenugreek has no adverse effects on human liver, kidney, or thyroid function. Studies have shown that oral administration of high doses of fenugreekine to rats does not cause serious adverse reactions. Currently, both in vivo and in vitro experiments have confirmed that fenugreekine possesses various biological effects, including anti-diabetic, anti-obesity, anti-fibrotic, antioxidant, anti-inflammatory, antiviral, antibacterial, antitumor, lipid-regulating, cardiovascular-protective, and neuroprotective effects. However, its application in plants is subject to limited research. Research on its inhibitory effect on algal growth is even scarcer. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for preparing trigonelline inner salt and its application in inhibiting algal growth, addressing the shortcomings of the prior art.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides the application of trigonelline inner salt in inhibiting algal growth and / or killing algae, wherein the trigonelline inner salt has the chemical structure shown in Formula I: Formula I.
[0007] The molecular formula is C7H7NO2.
[0008] Preferably, the application method is as follows: add trigonelline endospermum salt to water containing algae, so that the concentration of trigonelline endospermum salt in the water is 1~4 mg / L.
[0009] This invention reveals that trigonelline endosalpingin has anti-algal and algicidal effects, showcasing a novel application value for this product. In the verification of its anti-algal activity against Microcystis aeruginosa, this invention demonstrated its inhibitory effect, particularly at higher concentrations and for longer durations, showing a negative growth trend in algal cells, and exhibiting concentration dependence. Trigonelline endosalpingin is a natural product extracted from coffee and fenugreek, readily biodegradable, ecologically safe, and suitable for use in natural water bodies.
[0010] A second aspect of the present invention provides the use of trigonelline inner salt in the preparation of algicides and / or algae inhibitors that inhibit algal growth, the trigonelline inner salt having the chemical structure shown in Formula I: Formula I.
[0011] A third aspect of the present invention provides an agent that kills algae and / or inhibits algal growth, characterized in that it uses trigonelline inner salt having the chemical structure shown in Formula I as its active ingredient.
[0012] A fourth aspect of the present invention provides a method for preparing the inner salt of trigonelline, comprising the following steps: S1. Ethyl nicotinate is reacted with dimethyl sulfate in methanol to obtain N-methyl nicotinate monomethyl sulfate (4-ethoxycarbonyl-1-methyl-pyridinium; methyl sulfate). S2. N-methyl nicotinic acid ethyl sulfate monomethyl ester salt was reacted with alkali and thiourea in deionized water under heating and stirring to obtain crude trigonelline inner salt. S3. After adjusting the pH by adding acid to the crude trigonelline inner salt, methanol is added, the mixture is filtered, the solvent is concentrated, and then isopropanol is used to slurry the product to obtain the pure trigonelline inner salt. The reaction pathway of the inner salt of trigonelline is as follows: , In this context, MeSO4 represents dimethyl sulfate, and MeOH represents methanol.
[0013] Preferably, step S1 specifically involves: adding ethyl nicotinate to methanol, then adding dimethyl sulfate, stirring and reacting, and concentrating after the reaction is complete to obtain N-methyl nicotinate ethyl sulfate monomethyl ester salt.
[0014] Preferably, the reaction time of step 1 can be 4 hours, for example, it can be 1, 3, 4, 5, 7 hours or any value formed by any two of them, with 4 hours being the most preferred.
[0015] Preferably, the reaction temperature in step 1 can be 10-100℃, for example, 10℃, 20℃, 50℃, 80℃ or any value formed by any two of them, with the most preferred value being 25℃.
[0016] Preferably, the molar ratio of ethyl nicotinate to dimethyl sulfate in step 1 is 1:0.9 to 1:3, for example, it can be 1:1, 1:2, 1:3 or any value formed by any two of them, with the most preferred ratio being 1:1.2.
[0017] Preferably, in step S1, the volume of methanol used is 3 to 15 times the weight of ethyl nicotinate, in units of volume (L) and weight (kg). For example, it can be 3, 6, 9, 12, 15 times or any combination thereof, with 6 times being the most preferred.
[0018] Preferably, step S1 specifically involves: adding ethyl nicotinate to methanol, then adding dimethyl sulfate, stirring and reacting at 10-100°C for 1-7 hours, and concentrating after the reaction to obtain N-methyl nicotinate ethyl sulfate monomethyl ester salt.
[0019] Preferably, step S2 specifically involves adding deionized water and alkali to the product obtained in step S1, then adding thiourea, heating the reaction, and cooling to room temperature after the reaction is complete to obtain crude trigonelline inner salt.
[0020] Preferably, the alkali in step 2 includes, but is not limited to, calcium hydroxide, sodium hydroxide, potassium hydroxide, and lithium hydroxide, with calcium hydroxide being the most preferred.
[0021] Preferably, the molar ratio of ethyl nicotinate and calcium hydroxide in step 2 is 1:0.5 to 1:1.5, for example, it can be 1:0.5, 1:0.7, 1:1, 1:1.3, 1:1.5 or any value formed by any two of them, with 1:0.7 being the most preferred.
[0022] Preferably, the volume of water used in step 2 is 2 to 8 times the weight of ethyl nicotinic acid, in units of volume (L) and weight (kg). For example, it can be 2, 4, 6, 8 times or any combination thereof, with 4 times being the most preferred.
[0023] Preferably, the reaction temperature in step 2 can be 60-100℃, for example, it can be 60℃, 70℃, 80℃, 90℃, 100℃ or any value formed by any two of them, with 80℃ being the most preferred.
[0024] Preferably, the reaction time in step 2 can be 3 hours, for example, it can be 1, 3, 4, 5, 7 hours or any value formed by any two of them, with 3 hours being the most preferred.
[0025] Preferably, step S2 specifically involves adding deionized water and alkali to the product obtained in step S1, then adding thiourea, reacting at 60-100℃ for 1-7 hours, and cooling to room temperature after the reaction to obtain crude trigonelline inner salt.
[0026] Preferably, step S3 specifically includes: Add acid to the product obtained in step S2 to adjust the pH to acidic, then add a miscible solvent, filter, wash the filter cake with the miscible solvent, concentrate the filtrate under vacuum, add the concentrated product to a pulping solvent, pulp at 50~70℃ for 1~4h, then cool naturally to room temperature and stir for 0.5~1h, filter, wash the filter cake with the pulping solvent, and dry under vacuum to obtain pure trigonelline inner salt.
[0027] Preferably, the acid used as the pH-adjusting solvent in step 3 can be sulfuric acid, hydrochloric acid, nitric acid, or other inorganic acids, with sulfuric acid being the most preferred. The mass concentration of the sulfuric acid is 10% to 40%, for example, it can be 10%, 20%, 30%, 40%, or any value between any two of them, with 30% being the most preferred.
[0028] Preferably, in step S3, acid is used to adjust the pH to 6-6.5, and more preferably, the pH is adjusted to 6.5.
[0029] Preferably, the miscible solvent in step S3 is selected from at least one of methanol, ethanol, and isopropanol, with methanol being the most preferred.
[0030] Preferably, the pulping solvent in step S3 is selected from at least one of methanol, ethanol, and isopropanol, with isopropanol being the most preferred.
[0031] The beneficial effects of this invention are: This invention also provides a method for preparing trigonelline inner salt and its application in inhibiting algal growth and / or killing algae. In the preparation method of this invention, inexpensive and readily available ethyl nicotinate is used as a raw material, and dimethyl sulfate is used as a methyl source for methylation under methanol solvent conditions. The final product, trigonelline inner salt, is then obtained by reflux with equivalent amounts of calcium hydroxide and thiourea. This invention has found that using dimethyl sulfate as a methylating agent and using thiourea can remove the residue of monomethyl sulfate, thereby effectively reducing synthesis costs, avoiding the use of large amounts of hazardous reagents, eliminating the residue of toxic reagents, effectively reducing the generation of industrial waste, and the process is simple, convenient to operate, uses inexpensive and readily available raw materials, and has a high yield, which is conducive to large-scale industrial production.
[0032] This invention demonstrates that trigonelline internal salt exhibits significant inhibitory effects on Microcystis aeruginosa at different concentrations, showing a concentration-dependent effect. Experimental studies show that trigonelline internal salt has a significant effect on inhibiting algal growth and killing algae, and can be used as an algicide or to suppress algal blooms in aquatic bodies. Attached Figure Description
[0033] Figure 1 The NMR spectrum of the pure trigonelline inner salt prepared in Example 1; Figure 2 Curve showing the inhibition of chlorophyll a concentration in Microcystis aeruginosa by the internal salt of trigonelline. Figure 3 The inhibition rate curve of trigonelline inner salt inhibiting the concentration of chlorophyll a in Microcystis aeruginosa; Figure 4 Curves showing the inhibition of chlorophyll a in Microcystis aeruginosa by different concentrations of trigonelline internal salt. Figure 5 Curves showing the inhibition rates of different concentrations of trigonelline internal salts on chlorophyll a in Microcystis aeruginosa. Figure 6 Comparison of the inhibition of Microcystis aeruginosa by different concentrations of trigonelline internal salt at 7 days of culture; Figure 7 Curve showing the inhibition of Microcystis aeruginosa cell density by trigonelline internal salt; Figure 8 The inhibition rate curve of trigonelline inner salt on the cell density of Microcystis aeruginosa. Figure 9 A comparative diagram showing the inhibition of Microcystis aeruginosa by trigonelline internal salt over a long period of time. Detailed Implementation
[0034] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.
[0035] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.
[0036] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.
[0037] Example 1 A method for preparing a trigonelline inner salt includes the following steps: S1. Preparation of N-methylnicotinic acid ethyl ester sulfate monomethyl ester salt Add 0.3 L of methanol to a 10 L three-necked flask, then add ethyl nicotinate (50 g, 0.33 mol), and slowly add dimethyl sulfate (50 g, 0.4 mol) in batches. After the addition is complete, keep the mixture at 25 °C and stir thoroughly for 4 h. After monitoring the raw material concentration by HPLC to be less than 1%, concentrate the reaction solution until no solvent drips out to obtain N-methyl nicotinate ethyl sulfate monomethyl ester salt. S2, crude synthetic trigonelline inner salt Add 0.2 L of deionized water and calcium hydroxide (14.8 g, 0.2 mol) to the product obtained in step S1, then add thiourea (25.2 g, 0.33 mol), heat to 80 °C, keep warm and stir for 3 h, and after the reaction is complete, let it cool naturally to room temperature of 25 °C to obtain crude trigonelline inner salt. S3, purification of crude trigonelline inner salt After adjusting the pH to 6.5 with 30wt% sulfuric acid, add 0.2L methanol to the product obtained in step S2, filter, wash the filter cake twice with methanol solution, and concentrate the filtrate under vacuum at 70℃. Add the concentrated product to 0.2L isopropanol, heat to 60℃ and stir for 2 hours, then cool naturally to room temperature (25℃) and stir for 1 hour. Filter, wash the filter cake with isopropanol to obtain wet trigonelline inner salt, and dry under vacuum at 50℃ to obtain 36.2g of pure trigonelline inner salt, with a yield of 79.8%.
[0038] The NMR spectrum of the pure trigonelline inner salt prepared in this embodiment is as follows: Figure 1 As shown, the NMR data are as follows: 1 HNMR (400 MHz, Deuterium Oxide) δ 9.12 (s, 1H),8.87 – 8.78 (m, 2H), 8.08 (t, J =7.1 Hz, 1H), 4.44 (s, 3H). Example 2 A method for preparing a trigonelline inner salt includes the following steps: S1. Preparation of N-methylnicotinic acid ethyl ester sulfate monomethyl ester salt Add 12 L of methanol to a 20 L three-necked flask, then add ethyl nicotinate (2000 g, 13.2 mol), followed by the slow addition of dimethyl sulfate (2000 g, 7.9 mol) in batches. After the addition is complete, maintain the temperature at 25 °C and stir thoroughly for 4 h. Monitor the reaction mixture by HPLC until the starting material is less than 1%, then concentrate the reaction solution until no solvent is released, yielding N-methyl nicotinate ethyl sulfate monomethyl ester salt. S2, crude synthetic trigonelline inner salt Add 8L of water and calcium hydroxide (590g, 3.97mol) to the product obtained in step S1, then add thiourea (1008g, 6.62mol), heat to 80℃, keep warm and stir for 3h, and after the reaction is complete, let it cool naturally to room temperature 25℃ to obtain crude trigonelline inner salt. S3, purification of crude trigonelline inner salt Add 30wt% sulfuric acid to the product obtained in step S2 to adjust the pH to 6.5, then add 8L of methanol, filter, wash the filter cake twice with methanol solution, and concentrate the filtrate under vacuum at 70℃; add the concentrated product to 8L of isopropanol, heat to 60℃ and stir for 2h, then cool naturally to room temperature (25℃) and stir for 1h, filter, wash the filter cake with isopropanol to obtain wet trigonelline inner salt, and dry under vacuum at 50℃ to obtain 1433g of pure trigonelline inner salt, with a yield of 78.87%.
[0039] Example 3: Experiment on inhibiting algal growth The algae suppression experiment process is as follows: Experimental materials: Reagents: Trigonelline inner salt prepared in Example 1, copper sulfate, chlorophyll a Algal species: Microcystis aeruginosa FACHB-914; purchased from the Freshwater Algae Culture Bank of the Chinese Academy of Sciences.
[0040] Experimental methods: 1. Inhibition curve and inhibition rate of trigonelline internal salt on Microcystis aeruginosa growth based on chlorophyll a concentration determination (1) Pre-culture of algal strains Before the experiment, the algal strain needed to be expanded. The culture medium was prepared based on BG11 medium, which was purchased from Shanghai Guandao Biotechnology Co., Ltd., and the preparation method was in accordance with the instructions. After culturing for 7-14 days, an appropriate amount of *Microcystis aeruginosa* sample was centrifuged at 5000 rpm for 15 min, the supernatant was discarded, and the sample was washed with 15 mg / L sodium bicarbonate solution, then centrifuged again. This process was repeated 2-4 times. The centrifuged algal sample was diluted with sterile double-distilled water and inoculated under sterile conditions. A certain amount of the experimental algal strain was serially diluted according to specific dilution factors. The cell count of the diluted algal sample was performed using a hemocytometer to obtain the corresponding algal cell count. The initial algal cell density was approximately 10-1. 5 per mL.
[0041] (2) Plotting the standard curve of chlorophyll a Accurately weigh chlorophyll a into volumetric flasks to prepare standard solutions with concentrations of approximately 0.05 mg / L, 0.1 mg / L, 0.2 mg / L, 0.5 mg / L, and 1 mg / L, respectively; measure the absorbance (OD) at 665 nm using a 723N spectrophotometer. 665And plot the concentration-absorbance standard curve.
[0042] (3) Determination of the growth curve of Microcystis aeruginosa inhibited by trigonelline inner salt 250mL glass conical flasks were used as experimental containers, each filled with 100mL of culture medium. The control group received no other reagents; the experimental groups received 1mL each of 500mg / L copper sulfate, 50mg / L and 200mg / L trigonelline inner salt in DMSO solution, and were shaken thoroughly to the corresponding concentrations. The flasks were placed in an incubator with a light intensity of 3000Lux, a temperature of 25℃, and a light-dark ratio of 12h:12h. To avoid uneven light distribution, the flasks were manually shaken 5–10 times daily, and their positions were interchanged. Samples were taken at 0, 1, 3, 5, and 7 days to determine the chlorophyll a concentration of *Microcystis aeruginosa*. Photos were taken for observation; comparative images are attached. Figure 9 .
[0043] Analytical method: Centrifuge 5 mL of the experimental solution at 5000 r / min for 5 min, discard the supernatant, then add an equal volume of 90% methanol solution and mix well. Extract at 4℃ in the dark for 4–6 h. Centrifuge the supernatant and measure the absorbance (OD) at 665 nm using a 723N spectrophotometer. 665 The mass concentration of chlorophyll a was determined based on the concentration-absorbance standard curve. Finally, growth curves were plotted with time on the x-axis and chlorophyll a mass concentration at different time points on the y-axis. Three replicates were performed for each time point. The t-test was used for significance analysis, and p < 0.05 was considered statistically significant. Experimental results are attached. Figure 2 .
[0044] The inhibition rate of chlorophyll a concentration in Microcystis aeruginosa was calculated using the following formula: , in, C control The chlorophyll a concentration is for the control group. C exp The concentration of chlorophyll a in the experimental group.
[0045] Plot the inhibition rate curves with time on the x-axis and the inhibition rate at different time points on the y-axis. The experimental results are attached. Figure 3 .
[0046] (4) Determination of the inhibition curve of chlorophyll a in Microcystis aeruginosa by different concentrations of trigonelline internal salt 250mL glass conical flasks were used as experimental containers, each filled with 100mL of culture medium. The control group received no other reagents; the experimental groups received 1mL of DMSO solution containing 12.5mg / L, 25mg / L, 50mg / L, 75mg / L, 100mg / L, 200mg / L, 400mg / L, 800mg / L, and 1600mg / L trigonelline inner salt, respectively, and were diluted to the corresponding concentrations by shaking. The flasks were placed in an incubator with a light intensity of 3000Lux, a temperature of 25℃, and a light-dark ratio of 12h:12h for cultivation. To avoid uneven light exposure, the flasks were manually shaken 5–10 times daily, and their positions were interchanged. Samples were taken at regular intervals on day 7 to determine the chlorophyll a concentration of *Microcystis aeruginosa*, and photographs were taken for observation. Comparison images are attached. Figure 6 .
[0047] Analytical method: Centrifuge 5 mL of the experimental solution at 5000 r / min for 5 min, discard the supernatant, then add an equal volume of 90% methanol solution and mix well. Extract at 4℃ in the dark for 4–6 h. Centrifuge the supernatant and measure the absorbance (OD) at 665 nm using a 723N spectrophotometer. 665 The mass concentration of chlorophyll a was determined based on the concentration-absorbance standard curve. Finally, a curve was plotted with concentration on the x-axis and chlorophyll a mass concentration at different concentrations on the y-axis. Three replicates were performed at each time point. The t-test was used for significance analysis, and p < 0.05 was considered statistically significant. Experimental results are attached. Figure 4 .
[0048] The inhibition rate of chlorophyll a concentration in Microcystis aeruginosa was calculated using the following formula: , in, C control The chlorophyll a concentration is for the control group. C exp The concentration of chlorophyll a in the experimental group.
[0049] Plot the inhibition rate curves with time on the x-axis and the inhibition rate at different time points on the y-axis. The experimental results are attached. Figure 5 .
[0050] 2. Inhibition curve and inhibition rate of trigonelline internal salt on Microcystis aeruginosa growth based on algal cell density determination (1) Pre-culture of algal strains The pre-culture method for algal strains is described in the previous section. The initial algal cell density is approximately 102. 5 per mL.
[0051] (2) Determination of the growth curve of Microcystis aeruginosa inhibited by trigonelline inner salt 250mL glass conical flasks were used as experimental containers, each filled with 100mL of culture medium. The control group received no other reagents; the experimental groups received 1mL each of 500mg / L copper sulfate, 50mg / L and 200mg / L trigonelline inner salt in DMSO solution, and were shaken thoroughly to the corresponding concentrations. The flasks were placed in an incubator with a light intensity of 3000Lux, a temperature of 25℃, and a light-dark ratio of 12h:12h. To avoid uneven light distribution, the flasks were manually shaken 5–10 times daily, and their positions were interchanged. Samples were taken at 0, 1, 3, 5, and 7 days to determine the cell density of *Microcystis aeruginosa*. Photos were taken for observation; comparative images are attached. Figure 9 .
[0052] Analytical methods: 5 mL of the experimental solution was serially diluted according to specific dilution factors. Cell counts were performed on the diluted algal samples using a hemocytometer to obtain the corresponding algal cell counts. Finally, growth curves were plotted with time on the x-axis and algal cell density at different time points on the y-axis. Three replicates were performed for each time point. The t-test was used for significance analysis, and p < 0.05 was considered statistically significant. Experimental results are attached. Figure 7 .
[0053] The inhibition rate of chlorophyll a concentration in Microcystis aeruginosa was calculated using the following formula: , in, CD control The algal cell density is the control group. CD exp The density of algal cells in the experimental group.
[0054] Plot the inhibition rate curves with time on the x-axis and the inhibition rate at different time points on the y-axis. The experimental results are attached. Figure 8 .
[0055] Experimental results: 1. For example Figure 2 , 3 As shown in Figures 7 and 8, the addition of trigonelline internal salt during the cultivation process significantly inhibited the normal growth of *Microcystis aeruginosa*, with statistically significant differences. Compared with copper sulfate (5 mg / L), trigonelline internal salt showed little difference in its inhibitory effect on *Microcystis aeruginosa* growth at low concentrations (0.5 mg / L) over a short period (1–3 days), but its inhibitory effect was significantly better than copper sulfate over a longer period (5–7 days). Furthermore, at higher concentrations (2 mg / L), the inhibitory effect of trigonelline internal salt was superior to copper sulfate at all time points. Figure 9 The inhibitory effect of trigonelline internal salts can be observed directly by comparing the colors of the culture medium in the conical flask.
[0056] 2. For example Figure 4 , 5 As shown, trigonelline internal salts at different concentrations all showed significant inhibitory effects on Microcystis aeruginosa, and the effect was concentration-dependent. Considering both cost and inhibitory effect, the most suitable concentration range was 1-4 mg / L. Figure 6 The inhibitory effect of trigonelline internal salts can be observed directly by comparing the colors of the culture medium in the conical flask.
[0057] The above experimental results show that trigonelline inner salt has a significant effect on inhibiting algal growth and killing algae, and can be used as an algaecide or to inhibit algal blooms in water bodies.
[0058] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.
Claims
1. Application of trigonelline inner salt in inhibiting algal growth and / or killing algae, wherein the trigonelline inner salt has the chemical structure shown in Formula I: Formula I.
2. Application of trigonelline inner salt in the preparation of algicides and / or algae inhibitors that inhibit algal growth, wherein the trigonelline inner salt has the chemical structure shown in Formula I: Formula I.
3. A formulation for killing and / or inhibiting algae growth, characterized in that, Its active ingredient is the trigonelline inner salt with the chemical structure shown in Formula I.
4. A method for preparing a trigonelline inner salt, characterized in that, Includes the following steps: S1. Ethyl nicotinate is reacted with dimethyl sulfate in methanol to obtain N-methyl nicotinate monomethyl sulfate salt; S2. N-methyl nicotinic acid ethyl sulfate monomethyl ester salt was reacted with alkali and thiourea in deionized water under heating and stirring to obtain crude trigonelline inner salt. S3. After adjusting the pH by adding acid to the crude trigonelline inner salt, methanol is added, the mixture is filtered, the solvent is concentrated, and then isopropanol is used to slurry the product to obtain the pure trigonelline inner salt. The reaction pathway of the inner salt of trigonelline is as follows: ， In this context, MeSO4 represents dimethyl sulfate, and MeOH represents methanol.
5. The method for preparing the inner salt of trigonelline according to claim 4, characterized in that, Step S1 is as follows: Ethyl nicotinic acid is added to methanol, then dimethyl sulfate is added, and the mixture is stirred at 10-100℃ for 1-7 hours. After the reaction is completed, the mixture is concentrated to obtain N-methyl nicotinic acid ethyl sulfate monomethyl ester salt.
6. The method for preparing the inner salt of trigonelline according to claim 5, characterized in that, In step S1: The molar ratio of ethyl nicotinate to dimethyl sulfate is 1:0.9 to 1:3; In terms of volume (L) and weight (kg), the volume of methanol used is 3 to 15 times the weight of ethyl nicotinate.
7. The method for preparing the inner salt of trigonelline according to claim 4, characterized in that, Step S2 is as follows: Add deionized water and alkali to the product obtained in step S1, then add thiourea, and react at 60-100℃ for 1-7 hours. After the reaction is completed, cool to room temperature to obtain crude trigonelline inner salt.
8. The method for preparing the inner salt of trigonelline according to claim 7, characterized in that, In step S2: The alkali is at least one of calcium hydroxide, sodium hydroxide, potassium hydroxide, and lithium hydroxide; The molar ratio of ethyl nicotinate to alkali is 1:0.5 to 1:1.5; In terms of volume (L) and weight (kg), the volume of deionized water used is 2 to 8 times the weight of ethyl nicotinic acid.
9. The method for preparing the inner salt of trigonelline according to claim 4, characterized in that, Step S3 is as follows: Add acid to the product obtained in step S2 to adjust the pH to acidic, then add a miscible solvent, filter, wash the filter cake with the miscible solvent, concentrate the filtrate under vacuum, add the concentrated product to a pulping solvent, pulp at 50~70℃ for 1~4h, then cool naturally to room temperature and stir for 0.5~1h, filter, wash the filter cake with the pulping solvent, and dry under vacuum to obtain pure trigonelline inner salt.
10. The method for preparing the inner salt of trigonelline according to claim 9, characterized in that, In step S3, the pH is adjusted to 6-6.5 using an acid, which is at least one of sulfuric acid, hydrochloric acid, and nitric acid. The miscible solvent and the pulping solvent in step S3 are both selected from at least one of methanol, ethanol, and isopropanol.