A COS-O-decanoyl chloride derivative, preparation method and application thereof

Abstract

The invention discloses a COS-O-decanoyl chloride derivative, a preparation method and an application thereof. The COS-O-decanoyl chloride derivative is a compound obtained by modifying a chitosan oligosaccharide hydroxyl group with decanoyl chloride; the preparation method is carried out according to the following steps: weighing a certain amount of chitosan oligosaccharide, dissolving the chitosan oligosaccharide in methanesulfonic acid under ice-water bath conditions to fully react, and obtaining a chitosan oligosaccharide methanesulfonate solution; adding the chitosan oligosaccharide to a NaOH solution, stirring the reaction at room temperature until dissolved, and then adding decanoyl chloride dropwise according to a molar ratio of chitosan oligosaccharide to decanoyl chloride of 1:10-30 to continue the reaction for 1-3 hours; adding ammonia water to react to obtain a suspended substance, washing with anhydrous ethanol and acetone in turn, and freeze-drying to obtain a COS-O-decanoyl chloride derivative. Compared with chitosan oligosaccharide, the COS-O-decanoyl chloride derivative effectively improves the antibacterial property against Rhizoctonia solani, and can be used to prepare drugs for preventing and treating rice sheath blight.

Description

Technical Field

[0001] The invention relates to a chitosan oligosaccharide derivative, a preparation method and application thereof, in particular to a COS-O-decanoyl chloride derivative, a preparation method and application thereof. Background Art

[0002] Rice sheath blight is one of the most common diseases of rice. It is a fungal disease caused by Rhizoctonia solani. It often causes unfilled grains and increased empty shell rates. In severe cases, it can cause plants to fall over and die, seriously affecting rice cultivation. In the past, rice sheath blight was controlled by pesticides, which not only produced resistance but also led to pesticide residues in rice, making it difficult to ensure food security.

[0003] Chitosan oligosaccharide (COS) is obtained by degradation of chitosan by acid hydrolysis, oxidation, physical method and other methods. It is the only positively charged alkaline amino oligosaccharide in nature with a degree of polymerization of 2-20. Compared with chitosan, chitosan oligosaccharide is non-toxic, has a low molecular weight and better water solubility. Studies have shown that chitosan oligosaccharide has antibacterial activity and has a certain inhibitory effect on the growth and reproduction of bacteria and fungi, but the antibacterial activity is usually weak. The structure of chitosan oligosaccharide is relatively special. Its molecules contain active amino and hydroxyl groups, which are easy to react chemically. The amino group at C2 and the hydroxyl groups at C3 and C6 are active groups. If these active sites are modified by introducing other groups, different chitosan oligosaccharide derivatives can be prepared, thereby changing the biological activity of chitosan oligosaccharide. However, there has been no report on the use of chitosan oligosaccharide as a raw material, using decanoyl chloride to chemically modify COS-O-decanoyl chloride derivatives to significantly improve the activity of inhibiting Rhizoctonia solani, so as to be used in the prevention and control of rice sheath blight. Summary of the invention

[0004] The present invention aims to solve the above technical problems existing in the prior art and provides a COS-O-decanoyl chloride derivative, a preparation method and an application thereof.

[0005] The technical solution of the present invention is: a COS-O-decanoyl chloride derivative, characterized by the following structural formula:

[0006] .

[0007] A method for preparing the above-mentioned COS-O-decanoyl chloride derivative is carried out according to the following steps:

[0008] Step 1. Weigh a certain amount of chitosan oligosaccharide, dissolve the chitosan oligosaccharide in methanesulfonic acid in an ice water bath to fully react, and obtain a chitosan oligosaccharide methanesulfonate solution;

[0009] Step 2. Add the chitosan oligosaccharide methane sulfonate solution to NaOH, stir and react at room temperature until dissolved, then add decanoyl chloride dropwise according to the molar ratio of chitosan oligosaccharide to decanoyl chloride of 1:10-30 and continue the reaction for 1-3 hours;

[0010] Step 3. Add ammonia water to react to obtain a suspension, wash it with anhydrous ethanol and acetone in sequence, and freeze-dry it to obtain a COS-O-decanoyl chloride derivative.

[0011] An application of the COS-O-decanoyl chloride derivative in the preparation of a drug for preventing and controlling rice sheath blight.

[0012] The present invention modifies the hydroxyl group of chitosan oligosaccharide with decanoyl chloride to synthesize COS-O-decanoyl chloride derivatives, which effectively improve the antibacterial activity against Rhizoctonia solani compared with chitosan oligosaccharide and can be used to prepare drugs for preventing and treating rice sheath blight. Compared with traditional chemical modification methods, the present invention has the advantages of simple operation and rapid reaction. The reactions are all carried out at room temperature (18-25°C), which not only saves energy but also avoids the destruction of the derivative structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the infrared spectrum of COS-O-decanoyl chloride derivative and chitosan oligosaccharide in the embodiment of the present invention.

[0014] Figure 2 It is the X-ray diffraction pattern of COS-O-decanoyl chloride derivative and chitosan oligosaccharide in the embodiment of the present invention.

[0015] Figure 3 It is the raw material chitosan oligosaccharide used in the embodiment of the present invention 1 H NMR image.

[0016] Figure 4 It is the COS-O-decanoyl chloride derivative of the embodiment of the present invention. 1 H NMR image.

[0017] Figure 5 This is a graph showing the anti-Rhizoctonia solani effect of COS-O-decanoyl chloride derivatives, chitosan oligosaccharides and sterile water in an example of the present invention. DETAILED DESCRIPTION

[0018] The preparation method of the COS-O-decanoyl chloride derivative of the present invention is carried out according to the following steps:

[0019] Step 1. Weigh 0.005 mol chitosan oligosaccharide (COS), dissolve it in 7.5 g methane sulfonic acid in an ice-water bath and react for 2 h to form a chitosan oligosaccharide methane sulfonate solution;

[0020] Step 2. Add the chitosan oligosaccharide methane sulfonate solution to 40% w / v NaOH, stir and react at room temperature for 3 hours until dissolved, then add 19.07 g of decanoyl chloride dropwise according to the mass ratio of chitosan oligosaccharide to decanoyl chloride of 1:20 and continue to react for 3 hours, and the modified product appears;

[0021] Step 3. Add ammonia water and react for 3 h to obtain a suspension, which was washed three times with anhydrous ethanol and acetone, and freeze-dried to obtain a COS-O-decanoyl chloride derivative, named COS-C 10 .

[0022] The raw materials used in the examples are all commercially available products, wherein the degree of polymerization of chitosan oligosaccharide is 2-50, and the degree of deacetylation is at least 90%; the molecular formula of decanoyl chloride is C 10 H 19 ClO, molecular weight is 190.71.

[0023] The reaction formula is as follows:

[0024] .

[0025] experiment:

[0026] 1. Chitosan oligosaccharide raw materials used in the examples of the present invention and the resulting COS-O-decanoyl chloride derivatives (COS-C 10 ) spectral analysis

[0027] The chitosan oligosaccharide (COS) used in the embodiment of the present invention and the prepared COS-O-decanoyl chloride derivative (COS-C 10 ) were mixed and ground with potassium bromide at a mass ratio of 1:100, and infrared spectra were measured by potassium bromide tablet method with a scanning range of 4000-400 cm -1 , the number of scans was 72, and the resolution was 4 cm -1 , infrared spectrum such as Figure 1 shown.

[0028] from Figure 1 It can be seen that 3400cm -1 The broad peak at is the superimposed absorption peak of NH and OH stretching vibration, which is the characteristic peak of chitosan oligosaccharide. 10 At 3400cm -1 The OH stretching vibration at 1560 cm -1 and 1435cm -1 A new set of absorption peaks at 2960-2850 cm -1 A stronger absorption peak appeared at 1520 cm -1The stretching vibration of NH still exists, which shows that the hydroxyl group of chitosan oligosaccharide has been successfully introduced into decanoyl chloride.

[0029] 2. Chitosan oligosaccharide raw materials used in the present invention and the resulting COS-O-decanoyl chloride derivative (COS-C 10 ) XRD analysis

[0030] The chitosan oligosaccharide (COS) used in the embodiment of the present invention and the prepared COS-O-decanoyl chloride derivative (COS-C 10 ) were ground separately, added with anhydrous ethanol and spread on a silicon plate. After the anhydrous ethanol evaporated, XRD analysis was performed. The scanning conditions were Cu target, scanning temperature 25°C, scanning speed 4° / min, scanning range 5-80°, and the X-ray diffraction pattern was as follows Figure 2 shown.

[0031] from Figure 2 It can be seen that chitosan oligosaccharide has two diffraction absorption peaks at 2θ=9° and 2θ=21.5°, which is related to the crystal morphology of chitosan oligosaccharide molecules; the modified chitosan oligosaccharide derivative (COS-C 10 ), the maximum diffraction angle peak position of its X-ray diffraction pattern shifted to the right, and the maximum diffraction angle peak intensity increased. New absorption peaks appeared at 2θ=30°, 40°, 45°, 56° and 75°, indicating that the addition of decanoyl chloride changed the crystal form of chitosan oligosaccharide.

[0032] 3. Chitosan oligosaccharide raw materials used in the present invention and the resulting COS-O-decanoyl chloride derivative (COS-C 10 ) by H NMR spectrum analysis

[0033] Weigh a small amount of chitosan oligosaccharide (COS) and COS-O-decanoyl chloride derivative (COS-C 10 ) was transferred to an NMR tube, DMSO-d6 was transferred to the NMR tube using a pipette, and the mixture was shaken until fully dissolved before hydrogen spectrum measurement.

[0034] COS 1 H NMR spectra and COS-C10 1 H NMR images are as follows Figure 3 , Figure 4 As shown. Figure 3 , Figure 4It can be seen that the absorption peak at δ=1.91ppm is the chemical shift of the methyl group on the acetyl group that has not been completely removed from chitosan oligosaccharide, δ=3.0-3.75ppm is the chemical shift of the H on the glucosamine and N-acetylglucosamine residues on the chitosan oligosaccharide sugar ring, which is the characteristic peak of chitosan oligosaccharide, and δ=2.51ppm is the absorption peak of the solvent. Compared with chitosan oligosaccharide, COS-O-decanoyl chloride derivatives have a new chemical shift at δ=0.86ppm, which is the chemical shift of the methyl group (-CH3) at the end of the acyl chain, which is a characteristic peak of the derivative. The chemical shift of the proton on the glucosamine residue at δ=1.80ppm has not changed and still exists, indicating that the hydroxyl group of chitosan oligosaccharide reacts with decanoyl chloride. The NMR results are consistent with the IR results, indicating that the COS-O-decanoyl chloride derivatives were successfully synthesized.

[0035] Chitosan oligosaccharide raw materials used in the present invention and the resulting COS-O-decanoyl chloride derivative (COS-C 10 ) against Rhizoctonia solani

[0036] Rhizoctonia solani (China Agricultural Microbiological Culture Collection Center, ACCC 36246) was inoculated into the culture medium by the spot inoculation method and cultured at 25°C.

[0037] The samples (the raw material chitosan oligosaccharide used in the embodiment of the present invention and the obtained COS-O-decanoyl chloride derivative) were mixed with the culture medium to prepare drug-containing plates with concentrations of 2 mg / mL, 1 mg / mL, 0.5 mg / mL, 0.25 mg / mL, 0.125 mg / mL, and 0 mg / mL, respectively, and the culture medium with an equal volume of water added was used as the blank control (CK). A bacterial cake was taken from the culture medium of the target strain cultured with a 0.7 cm puncher and placed in the center of the drug plate with the hyphae facing down. The plates were cultured in an incubator at 25°C, and the hyphae growth diameter was measured by the cross method. The inhibition rate was calculated using Excel software, and each treatment was repeated three times.

[0038] Mycelium growth inhibition rate (100%) = (control colony diameter - treated colony diameter) / (control colony diameter - 0.7 cm) × 100%

[0039] The experimental results are as follows Figure 5 As shown in Table 1.

[0040] Table 1

[0041]

[0042] The COS-O-decanoyl chloride derivative obtained in the embodiment of the present invention has strong antibacterial activity against Rhizoctonia solani, and the antibacterial rate is significantly higher than that of chitosan oligosaccharide, and can be used in the preparation of drugs for preventing and controlling rice sheath blight.

Claims

1. A COS-O-decanoyl chloride derivative, characterized in that The structural formula is as follows: Said n=2-50.

2. A method for preparing a COS-O-decanoyl chloride derivative as claimed in claim 1, characterized in that Follow these steps: Step 1. Weigh a certain amount of chitosan oligosaccharide, wherein the chitosan oligosaccharide has a degree of polymerization of 2-50 and a degree of deacetylation of at least 90%, and dissolve the chitosan oligosaccharide in methane sulfonic acid in an ice water bath to react sufficiently to obtain a chitosan oligosaccharide methane sulfonate solution; Step 2. Add the chitosan oligosaccharide methane sulfonate solution to NaOH, stir and react at room temperature until dissolved, then add decanoyl chloride dropwise according to the molar ratio of chitosan oligosaccharide to decanoyl chloride of 1:10-30 and continue the reaction for 1-3 hours; Step 3. Add ammonia water to react until a suspension is obtained, wash with anhydrous ethanol and acetone in sequence, and freeze-dry to obtain a COS-O-decanoyl chloride derivative.

3. Use of the COS-O-decanoyl chloride derivative as claimed in claim 1 in the preparation of a drug for preventing and controlling rice sheath blight.

Images