Stable garlicin water solution and its preparation method and application

Abstract

The application discloses a stable allicin water agent and a preparation method and application thereof, and belongs to the technical field of agricultural chemical preparations. The water agent is composed of 2-20% of chemically synthesized allicin, 0.5-5% of a water-soluble colloidal protective agent, 0.1-2% of an antioxidative synergist, 3-10% of a surfactant, 3-8% of an antifreezing agent and the balance of deionized water. The water-soluble colloidal protective agent forms a physical barrier, and the antioxidative synergist provides chemical antioxidative protection, so that a double stable system is constructed, and the light, heat and oxygen stability of the allicin is remarkably improved. The preparation has excellent control effects on fungal diseases such as gray mold and powdery mildew, bacterial diseases such as bacterial wilt, and has rapid contact-killing activity and sustained control capacity on agricultural pests such as chinch bugs, red spiders and aphids, and has a long effective period, is safe to use and simple in preparation process, and has a wide application prospect in the field of green agricultural pest control.

Description

Technical Field

[0001] This invention relates to the field of agricultural chemical formulation technology, and in particular to a stable allicin aqueous solution, its preparation method, and its application. Background Technology

[0002] Allicin (chemical name diallyl thiosulfinate) is an active ingredient derived from natural garlic. It possesses broad-spectrum biological activity and can significantly inhibit or kill various plant pathogenic fungi, bacteria, and agricultural pests. Compared to traditional chemical pesticides, allicin has advantages such as good environmental compatibility, easy degradation, no residue, and less likelihood of inducing pesticide resistance in pests and diseases. It aligns with the current development concepts of green and ecological agriculture and has significant application potential in the field of green control of crop diseases and pests.

[0003] However, allicin still faces numerous technical bottlenecks in large-scale agricultural applications, severely limiting its industrialization and application. First, allicin obtained through natural extraction suffers from low content, complex extraction processes, and high production costs, making it difficult to meet the economic demands of large-scale field agriculture. Second, the active sulfur groups in the allicin molecule are highly susceptible to external factors such as light, heat, and oxygen, undergoing oxidative decomposition reactions and transforming into non-biologically active disulfides and other products, leading to a rapid decline in its efficacy. Third, existing conventional formulations, such as emulsifiable concentrates and soluble concentrates, lack effective protective mechanisms for allicin, failing to mitigate its oxidative decomposition rate and further exacerbating the problem of efficacy loss.

[0004] To address the aforementioned issues, existing technologies have attempted to improve the stability of allicin through compound additives and encapsulation techniques, but significant drawbacks remain: some encapsulation processes are complex and require substantial equipment investment, leading to a significant increase in formulation costs; some compound formulations rely solely on antioxidants, resulting in limited protective effects and failing to meet the needs of long-term storage and use under different environmental conditions; and other formulations suffer from poor dosage form compatibility, easy stratification during use, and uneven efficacy.

[0005] The emergence of chemically synthesized allicin has effectively solved the problems of limited sources and high costs associated with natural allicin. However, its chemical stability is worse than that of naturally extracted allicin, and it requires a more robust protection system. Therefore, developing a formulation that is scientifically formulated, simple in process, can effectively improve the stability of chemically synthesized allicin, and also possesses excellent disease and insecticidal effects suitable for large-scale production has become a research hotspot in the field of agricultural formulations, and has significant theoretical and practical value. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing allicin preparations, such as poor stability, complex processes, and high costs, and to provide a stable allicin aqueous solution. By constructing a physical-chemical dual stability system, the stability of chemically synthesized allicin is significantly improved, and the duration of efficacy is extended.

[0007] Another objective of this invention is to provide a method for preparing the above-mentioned stable allicin aqueous solution, which is simple in process, controllable in operation, requires no special equipment, and is suitable for large-scale industrial production.

[0008] Another objective of this invention is to provide the application of the above-mentioned stable allicin aqueous solution in the prevention and control of crop diseases and pests, so as to achieve efficient control of fungal diseases, bacterial diseases and common pests, and provide a new formulation option for green agriculture.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A stabilized allicin aqueous solution comprises the following components by weight percentage: Chemically synthesized allicin 2%-20%, water-soluble colloidal protectant 0.5%-5%, antioxidant synergist 0.1%-2%, surfactant 3%-10%, antifreeze 3%-8%, deionized water to make up to 100%.

[0010] Furthermore, the water-soluble colloidal protective agent is one or more of xanthan gum, carrageenan, and gellan gum; the antioxidant synergist is one or more of L-ascorbic acid, sodium isovitamin C, phytic acid, and citric acid.

[0011] Furthermore, the surfactant is an alkyl glycoside or a fatty alcohol polyoxyethylene ether nonionic surfactant; the antifreeze is one of glycerol, ethylene glycol, and polyethylene glycol.

[0012] A method for preparing a stable allicin aqueous solution includes the following steps: a) Add the water-soluble colloidal protectant to a portion of deionized water, and shear and stir under heating conditions to completely dissolve the water-soluble colloidal protectant and form a homogeneous colloidal aqueous phase, then cool to room temperature; b) Take chemically synthesized allicin, surfactant and antioxidant synergist in proportion, place them in a mixing container and stir evenly to form a homogeneous oil phase; c) While maintaining the shearing state, slowly add the oil phase to the colloidal aqueous phase, and continue shearing until a stable crude emulsion is formed; d) The crude emulsion is placed in a high-pressure homogenizer and homogenized under a pressure of 20-50 MPa for 3-5 cycles to obtain a uniform and stable colloidal dispersion system. e) Add antifreeze to the homogenized colloidal dispersion system, stir to dissolve, add deionized water to the set total amount, continue stirring for 15-30 minutes, and mix evenly to obtain stable allicin aqueous solution.

[0013] The beneficial effects of this invention are as follows: 1. Significantly improved stability: This invention constructs a dual physical-chemical stability system. The water-soluble colloidal protectant forms a three-dimensional network physical barrier, while the antioxidant synergist provides chemical antioxidant protection. The two work synergistically to effectively delay the oxidative decomposition of allicin, which can meet the needs of long-term storage and use under different environmental conditions. 2. Controllable cost and suitable for large-scale production: The use of chemically synthesized allicin to replace naturally extracted allicin solves the problems of limited sources and high costs of natural allicin; the preparation process is simple, requires no special equipment, the operation steps are controllable, the production efficiency is high, and large-scale industrial production can be realized. 3. Excellent disease and insect control effects: The formulation has a high-efficiency control effect on fungal diseases such as gray mold and powdery mildew, and bacterial diseases such as bacterial wilt. At the same time, it has rapid contact killing activity and continuous control ability against common agricultural pests such as thrips, spider mites and aphids. The control effect is better than or equal to that of existing conventional pesticides. 4. High safety and environmental friendliness: All components of the formulation are non-toxic or low-toxic substances with good biodegradability and no residual pollution. It is safe for crops, natural enemies and humans, and meets the development requirements of green agriculture and ecological agriculture. It can be widely used in various crops such as fruits, vegetables, grains and cotton. 5. Significant advantages of formulation: The aqueous formulation is convenient to use, can be directly diluted with water for spraying or root irrigation, has good dispersibility and uniform efficacy, and has strong adhesion to the crop surface, which can effectively improve the utilization rate of the pesticide and avoid waste of resources. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a process flow diagram for preparing the stable allicin aqueous solution of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] A stabilized allicin aqueous solution comprises the following components by weight percentage: Chemically synthesized allicin: 2%-20%, as the core active ingredient, has broad-spectrum disease prevention and insecticidal activity. Compared with naturally extracted allicin, it has lower cost and more stable content, which can meet the needs of large-scale application. Water-soluble colloidal protectant: 0.5%-5%, used to form a physical protective barrier, blocking oxygen from contacting allicin and delaying oxidative decomposition; the water-soluble colloidal protectant is one or more of xanthan gum, carrageenan, and gellan gum. These colloids have good water solubility and thickening properties, and after dissolving, they can form a three-dimensional network structure, effectively encapsulating the active ingredient of allicin, physically blocking oxygen and light from contacting allicin, while improving the emulsification stability of the formulation and preventing stratification and precipitation. The protective effect is even better when xanthan gum and gellan gum are used in combination.

[0018] Antioxidant synergists: 0.1%-2%, used to scavenge oxygen free radicals in the system, inhibit the oxidation reaction of allicin's active sulfur groups, and provide chemical protection; antioxidant synergists are one or more of L-ascorbic acid, sodium isovitamin C, phytic acid, and citric acid. These antioxidants are highly efficient, non-toxic, and readily soluble in the system. They actively scavenge oxygen free radicals in the system and inhibit the oxidative decomposition reaction of allicin. Simultaneously, some components, such as citric acid, can adjust the pH value of the system, further enhancing the stability of allicin. When sodium isovitamin C is combined with phytic acid, the synergistic antioxidant effect is significant, improving the stability of allicin compared to a single antioxidant.

[0019] Surfactants: 3%-10%, used to improve the compatibility between the oil and aqueous phases, promote emulsification and dispersion, and enhance the stability and adhesion of the formulation to crop surfaces. The surfactants are alkyl glycosides or fatty alcohol polyoxyethylene ethers—nonionic surfactants. These surfactants have advantages such as strong emulsifying ability, good biodegradability, and environmental friendliness. They can effectively reduce the interfacial tension between the oil phase (chemically synthesized allicin) and the aqueous phase, promoting thorough mixing to form a stable emulsion. Simultaneously, they enhance the wetting and adhesion of the formulation to crop surfaces, thereby increasing the efficacy of the drug.

[0020] Antifreeze: 3%-8%, used to lower the freezing point of the formulation, prevent freezing at low temperatures from damaging the system's stability, and ensure effective low-temperature storage and use. The antifreeze is one of glycerol, ethylene glycol, or polyethylene glycol. These antifreezes have good water solubility and compatibility with the system. They not only effectively lower the freezing point of the formulation but also improve its moisture retention to some extent, extending the duration of efficacy. Glycerol, in particular, has higher safety and is more suitable for use on fruits and vegetables.

[0021] Deionized water: Add to 100% as a dispersion medium to ensure the homogeneity of the formulation and avoid the influence of impurities on the stability of allicin.

[0022] The present invention also provides a method for preparing the above-mentioned stable allicin aqueous solution, comprising the following steps: 1. Aqueous phase preparation: Add the water-soluble colloidal protective agent to a portion of deionized water (40%-60% of the total water volume), heat to 50-60℃, and simultaneously shear and stir at a speed of 800-1200 r / min for 20-30 minutes to completely dissolve the water-soluble colloidal protective agent and form a uniform and transparent colloidal aqueous phase. Allow it to cool naturally to room temperature for later use. 2. Oil phase preparation: Take chemically synthesized allicin, surfactant and antioxidant synergist in proportion, place them in a mixing container, and stir at 500-800 r / min for 10-15 minutes to fully mix the components and form a homogeneous and stable oil phase; 3. Primary emulsification: While maintaining the colloidal aqueous phase at a continuous shearing speed of 800-1200 r / min, slowly add the prepared oil phase dropwise to the colloidal aqueous phase at a dropping rate of 1-2 mL / min. After the addition is complete, continue shearing and stirring for 20-30 minutes to form a uniform crude emulsion. 4. High-pressure homogenization: The crude emulsion is placed in a high-pressure homogenizer and homogenized under a pressure of 20-50 MPa for 3-5 cycles to homogenize the emulsion particles (particle size controlled at 1-5 μm) and obtain a uniform and stable colloidal dispersion system. 5. Volume adjustment and stirring: Add antifreeze to the homogenized colloidal dispersion system and stir at 500-800 r / min for 10-15 minutes to completely dissolve the antifreeze. Then add the remaining deionized water to the set total volume and continue stirring for 15-30 minutes to ensure that all components are mixed evenly, thus obtaining the stable allicin aqueous solution.

[0023] Example 1: Preparation of 5% Stabilized Allicin Aqueous Solution Formula composition (weight percentage): 5% chemically synthesized allicin, 0.8% xanthan gum, 0.5% sodium iso-Vc, 5% alkyl glycoside, 5% glycerol, deionized water to 100%, prepared according to the above method, high pressure homogenization pressure 30MPa, cycled 4 times.

[0024] Example 2: Field trial for the control of tomato gray mold 1. Experimental materials: 5% stable allicin aqueous solution prepared in Example 1 of this invention, and 50% iprodione wettable powder (commercially available conventional agent) as the control agent.

[0025] 2. Experimental location: Greenhouse tomato garden in Shouguang, Shandong Province. The incidence of gray mold in the experimental tomato fields was moderate, and the plants were growing in a uniform manner.

[0026] 3. Experimental Design: Three treatment groups were set up, with three replicates per group. The plot area was 20㎡, and the experiment was conducted in a randomized block design. Treatment 1: Spray with a 1000-fold dilution of 5% stable allicin aqueous solution; Treatment 2: Spray with a 1500-fold dilution of 50% iprodione wettable powder; Treatment 3: Water control. Application was carried out at the initial stage of disease, once every 7 days, for a total of 2 applications.

[0027] 4. Investigation method: Disease incidence was investigated 7 days and 14 days after the last application of pesticide. 50 plants were randomly sampled from each plot, and the number of diseased leaves and disease severity were recorded to calculate the control effect.

[0028] 5. Experimental Results: The control efficacy of treatment 1 at 7 and 14 days after application was 88.5% and 85.1%, respectively; the control efficacy of treatment 2 was 82.3% and 78.6%, respectively; the disease severity in the water control group continued to worsen. These results indicate that the formulation of this invention is more effective than the conventional control agent in controlling tomato gray mold, and has a longer residual effect.

[0029] Example 3: Field trial for the control of cucumber powdery mildew 1. Experimental materials: 10% stable allicin aqueous solution prepared in Example 1 of this invention, and 25% ethirimol suspension (commercially available conventional agent) as the control agent.

[0030] 2. Experiment location: Open-field cucumber garden in Langfang, Hebei Province, where cucumbers were in the early flowering stage and powdery mildew was occurring sporadically.

[0031] 3. Experimental Design: Three treatment groups were set up, with three replicates per group, and each plot area was 15㎡. Treatment 1: 10% stable allicin aqueous solution diluted 1500 times and sprayed; Treatment 2: 25% ethirimol suspension diluted 2000 times and sprayed; Treatment 3: water control. One application was performed, and surveys were conducted at 7 days and 14 days after application.

[0032] 4. Experimental Results: The control efficacy of treatment 1 was 92.3% and 90.7% at 7 and 14 days after application, respectively; the control efficacy of treatment 2 was 93.1% and 89.5%, respectively. The results indicate that the formulation of this invention has comparable control efficacy against cucumber powdery mildew to the conventional control agent, and exhibits a superior duration of effect.

[0033] Example 4: Field trial for the control of bacterial wilt in tomatoes 1. Experimental materials: 5% stable allicin aqueous solution prepared in Example 1 of this invention, and the control agent is 2 billion CFU / g Bacillus amyloliquefaciens wettable powder (commercially available biological pesticide).

[0034] 2. Experimental site: A tomato field in Sanya, Hainan, where continuous cropping of tomatoes resulted in severe bacterial wilt and high levels of bacteria in the soil.

[0035] 3. Experimental Design: Three treatment groups were set up, with three replicates per group, and each plot area was 25㎡. Treatment 1: 5% stable allicin aqueous solution diluted 800 times was used for root irrigation, with 500mL of the solution per plant; Treatment 2: 2 billion CFU / g Bacillus amyloliquefaciens wettable powder was diluted 500 times and used for root irrigation, with 500mL of the solution per plant; Treatment 3: Control group was treated with plain water. Treatment began 10 days after transplanting, with applications every 10 days for a total of 3 applications.

[0036] 4. Experimental Results: A survey conducted 30 days after the last application showed that treatment 1 achieved a control efficacy of 76.8%, treatment 2 achieved a control efficacy of 62.3%, and the disease incidence rate in the water control group reached 85.2%. These results indicate that the formulation of this invention is significantly more effective than the control biological pesticide in controlling bacterial wilt of tomatoes.

[0037] Example 5: Field trial for the control of agricultural pests 1. Experimental materials: 5% stable allicin aqueous solution prepared in Example 1 of this invention, and the control agents are 25% thiamethoxam water-dispersible granules (for thrips control), 240 g / L spirodiclofen suspension (for spider mite control), and 25% imidacloprid wettable powder (for aphid control).

[0038] 2. Experimental Design: Experiments were conducted in chili fields (thrips) in Yuanmou, Yunnan; citrus orchards (red spider mites) in Ganzhou, Jiangxi; and cotton-producing areas (aphids) in Shihezi, Xinjiang. Each pest control experiment had three treatment groups (the formulation of this invention, the control formulation, and a water control group), with three replicates per group. The plot area was set at 15-30㎡ depending on the crop type. The dilution ratios of the formulation of this invention were: 1000 times for thrips, 1500 times for red spider mites, and 1200 times for aphids, all applied by spraying. The control formulation was used at the commercially recommended dosage.

[0039] 3. Experimental Results: For controlling pepper thrips, the efficacy of the formulation of this invention at 1, 3, and 7 days after application was 86.2%, 91.5%, and 89.3%, respectively, comparable to the control agent (87.5%, 92.1%, and 88.7%). For controlling citrus spider mites, the efficacy of the formulation of this invention at 1, 7, and 14 days after application was 82.7%, 90.1%, and 87.6%, respectively, compared to the control agent (83.2%, 91.3%, and 86.9%). For controlling cotton aphids, the efficacy of the formulation of this invention at 1, 3, and 7 days after application was 94.3%, 96.8%, and 93.2%, respectively, compared to the control agent (95.1%, 97.2%, and 92.8%). The results indicate that the formulation of this invention has comparable efficacy to conventional control agents in controlling thrips, spider mites, and aphids, possessing both rapid contact killing and sustained control capabilities.

[0040] Example 6: Stability Test 1. Experimental materials: The stable allicin aqueous solution prepared in Example 1 of this invention, and the control sample is ordinary allicin soluble solution (commercially available).

[0041] 2. Experimental method: Each sample was placed in a constant temperature chamber at 54±2℃ for 14 days. The content of allicin before and after heat storage was determined by high performance liquid chromatography (HPLC), and the decomposition rate was calculated.

[0042] 3. Experimental Results: The decomposition rate of the sample in Example 1 was 8.7%, while the decomposition rate of ordinary allicin soluble concentrate reached 52.3%. The results indicate that the stability of the formulation of this invention is significantly better than that of ordinary allicin formulation, and the dual stabilization system plays a good protective role.

[0043] In summary, the formulation of this invention has excellent control effects on fungal diseases such as gray mold and powdery mildew, as well as bacterial diseases such as bacterial wilt. At the same time, it has rapid contact killing activity and continuous control ability against agricultural pests such as thrips, spider mites, and aphids. It has a long-lasting effect, is safe to use, and has a simple preparation process, making it suitable for large-scale industrial production. It has broad application prospects in the field of green agricultural pest control.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A stable allicin aqueous solution, characterized in that, Includes the following components by weight percentage: Chemically synthesized allicin 2%-20%, water-soluble colloidal protectant 0.5%-5%, antioxidant synergist 0.1%-2%, surfactant 3%-10%, antifreeze 3%-8%, deionized water to make up to 100%.

2. The stabilized allicin aqueous solution according to claim 1, characterized in that, The water-soluble colloidal protective agent is one or more of xanthan gum, carrageenan, and gellan gum; the antioxidant synergist is one or more of L-ascorbic acid, sodium isosorbide dinitrate, phytic acid, and citric acid.

3. The stabilized allicin aqueous solution according to claim 1, characterized in that, The surfactant is an alkyl glycoside or a fatty alcohol polyoxyethylene ether nonionic surfactant; the antifreeze is one of glycerol, ethylene glycol, and polyethylene glycol.

4. A method for preparing a stable allicin aqueous solution as described in any one of claims 1-3, characterized in that, Includes the following steps: a) Add the water-soluble colloidal protectant to a portion of deionized water, and shear and stir under heating conditions to completely dissolve the water-soluble colloidal protectant and form a homogeneous colloidal aqueous phase, then cool to room temperature; b) Take chemically synthesized allicin, surfactant and antioxidant synergist in proportion, place them in a mixing container and stir evenly to form a homogeneous oil phase; c) While maintaining the shearing state, slowly add the oil phase to the colloidal aqueous phase, and continue shearing until a stable crude emulsion is formed; d) The crude emulsion is placed in a high-pressure homogenizer and homogenized under a pressure of 20-50 MPa for 3-5 cycles to obtain a uniform and stable colloidal dispersion system. e) Add antifreeze to the homogenized colloidal dispersion system, stir to dissolve, add deionized water to the set total amount, continue stirring for 15-30 minutes, and mix evenly to obtain stable allicin aqueous solution.

5. The application of the stable allicin aqueous solution as described in any one of claims 1-3 in the preparation of pesticides for the prevention and control of plant fungal diseases.

6. The application according to claim 5, characterized in that, The fungal disease mentioned is gray mold or powdery mildew.

7. The application of the stable allicin aqueous solution as described in any one of claims 1-3 in the preparation of pesticides for controlling plant bacterial diseases, characterized in that, The bacterial disease mentioned is bacterial wilt.

8. The use of the stable allicin aqueous solution as described in any one of claims 1-3 in the preparation of pesticides for controlling agricultural pests.

9. The application according to claim 8, characterized in that, The agricultural pests mentioned are thrips, spider mites, or aphids.

10. A method for preventing and controlling crop diseases and pests, characterized in that, The stable allicin aqueous solution according to any one of claims 1-3 is diluted with water 800-1500 times and applied to crops by spraying or root irrigation.

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