Chitosan oligosaccharide derivative with fragrance fixing and bacteriostasis functions as well as preparation method and application of chitosan oligosaccharide derivative

Abstract

The invention relates to a chitosan oligosaccharide derivative with fragrance fixing and bacteriostasis functions and a preparation method and application thereof.Chitosan oligosaccharide is used as a raw material for the first time to design and synthesize a perfume fixative with multiple functions of bacteriostasis, moisture preservation, good biocompatibility and the like, the synthesis reaction time is short, the yield is high, use of high-cost reaction reagents is avoided, the cost is low, and the cost is low. The reaction can be quantified, and industrial production can be realized.

Description

Technical Field

[0001] The invention relates to the field of chemical additives, and in particular to a chitosan oligosaccharide derivative with aroma-fixing and antibacterial functions, and a preparation method and application thereof. Background Art

[0002] Perfume is made by dissolving the fragrance in ethanol, and sometimes adding trace pigments, antioxidants, fungicides, glycerin, surfactants or other functional additives as needed. The ethanol concentration in perfume is 70%-90%. After normal use of perfume, ethanol as a solvent has a low boiling point and is easy to evaporate at room temperature, which can effectively release the volatile compounds in the perfume into the air. According to the volatilization time of the fragrance, the fragrance of the perfume can be divided into three fragrance stages: the top note of the top note, the base note of the middle note, and the end note of the tail note. The top note contains the most volatile components in the perfume. The base note appears immediately after the top note, exuding the main fragrance of the perfume, reflecting the main fragrance of a perfume, and generally lasts for at least 4 hours. The tail note is the most lasting part of the fragrance, that is, the slowest volatilization part, which can last for a day or longer.

[0003] The volatilization of perfume is a complex process. The volatile components in perfumes are usually small molecules with low polarity. As ethanol evaporates, the proportion of water will become higher and higher, and the polarity of the solution will become higher and higher. Some substances with low solubility and high concentration may aggregate and produce phase separation, which will significantly reduce the volatilization rate of perfume molecules. Although it prolongs the fragrance time of perfume to a certain extent, it will also affect the experience of using perfume. In order to solve this problem, a certain amount of so-called fixative is often added to the perfume formula to make the perfume components evaporate evenly (or prevent them from volatilizing quickly) and keep the fragrance of the essence unchanged during application, so that the fragrance of the essence will last longer. It can make the perfume have a certain fragrance retention time (generally 1-5 hours), which is crucial for locking the persistence of the fragrance.

[0004] It is generally believed that fixatives extend the fragrance retention time mainly based on three mechanisms: 1) Fixatives can form a permeable film on the surface of the fixed fragrance molecules or particles, thereby preventing the loss of volatile components in the fragrance. 2) The electrostatic attraction, hydrogen bonding or molecular association between fixatives and fragrances, and between fragrances and fragrance molecules results in a decrease in the vapor pressure of a certain fragrance or a certain component, thereby slowing down its evaporation rate, achieving the purpose of lasting and fixing the fragrance. 3) Due to the addition of fixatives, the threshold concentration of certain fragrances in the fragrance changes or its viscosity changes. Therefore, the same amount of fragrance is relatively easier for people to smell, or the time limit for being smelled by people is delayed, which also achieves the effect of increasing the fragrance persistence and fixing the fragrance.

[0005] There are many spices that can be used as fixatives, such as animal natural fragrance fixatives such as musk and civet; plant natural fragrances such as Peruvian resin, benzoin ester, vetiver oil, etc.; liquid or solid synthetic fragrances with high boiling points such as benzyl alcohol, synthetic musk, crystallized rose, vanillin, coumarin, acetoeugenol, benzyl benzoate, linalyl phenylacetate, etc. Most natural fixatives are expensive, while most synthetic fixatives are toxic and irritating to the eyes, respiratory tract and skin. Some even have certain allergenicity, mutagenicity, teratogenicity and carcinogenicity. The potential impact of long-term use cannot be ignored.

[0006] On the other hand, long-term use of perfume can also cause skin dehydration and dryness. In particular, sometimes specific parts of the skin may be exposed to certain adverse environments and may be infected by microorganisms or exposed to ultraviolet radiation. Therefore, if perfume can maintain its basic efficacy while achieving a longer antibacterial effect due to non-volatility, and is skin-friendly, and has a moisturizing effect on the skin and anti-ultraviolet radiation to a certain extent, it will definitely be in line with the future direction of green and healthy development. In view of this, developing a type of fixative with good biocompatibility and certain antibacterial and moisturizing effects is an important direction in perfume development. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention proposes a chitosan oligosaccharide derivative with aroma-fixing and antibacterial functions, and a preparation method and application thereof.

[0008] The technical solution of the present invention is as follows: A chitosan oligosaccharide derivative with aroma-fixing and antibacterial functions, the molecular structure of which is as follows: Denoted as C(A)GCO; where n=2~6.

[0009] A method for preparing the chitosan oligosaccharide derivative as described above comprises the following steps: Step 1) dissolve glycine and sodium carbonate in deionized water, cool to 0°C, add DMF solution of cinnamoyl chloride dropwise, stir for 2-4 h to complete the reaction; acidify with concentrated hydrochloric acid to pH = 1-2, then extract and wash with an equal amount of ethyl acetate, add anhydrous sodium sulfate and dry for 4-6 h; filter to remove the desiccant, and rotary evaporate the filtrate to obtain a white solid product cinnamoyl glycine; Step 2) dissolving acetylglycine and the product obtained in step 1) in DMF to obtain a DMF mixed solution, adding triethylamine, cooling to 0°C, adding an equivalent amount of pivaloyl chloride solution dropwise, gradually heating to room temperature and reacting for 2h, filtering to remove the white precipitate, and obtaining a mixed anhydride solution; Step 3) weigh appropriate amounts of chitosan oligosaccharide and sodium carbonate and dissolve them in a certain amount of deionized water, add the mixed anhydride solution obtained in step 2) dropwise, react for 3-4 hours, filter the reaction solution, precipitate with n-propanol and centrifuge, concentrate the centrifuge to 1 / 4, filter the filtrate and precipitate with solvent A, centrifuge and vacuum dry to obtain the chitosan oligosaccharide derivative (C(A)GCO).

[0010] Preferably, the molar ratio of the raw materials in step 1) is: glycine: sodium carbonate: cinnamoyl chloride = 1: 1.1-1.3: 1.1-1.4.

[0011] Preferably, the molar ratio of the raw materials in step 2) is: acetylglycine: cinnamoylglycine = 1: 1-3.

[0012] Preferably, the molar ratio of the raw materials in step 2) is: DMF mixed solution: triethylamine: pivaloyl chloride = 1: 1.0-1.05: 1.0-1.05.

[0013] Preferably, the molar ratio of the raw materials in step 3) is: mixed anhydride solution: sodium carbonate: chitosan oligosaccharide = 1: 1.0-1.05: 0.9-1.05.

[0014] Preferably, the solvent A used in step 3) is selected from tetrahydrofuran, ethyl acetate or propyl acetate.

[0015] The crude product obtained by the above process can also be used to obtain fine products according to the needs of different users by the following method: dissolve the crude chitosan oligosaccharide derivative in an appropriate amount of water, add a mixed solvent of n-propanol-ethyl acetate, precipitate, centrifuge, and vacuum dry to obtain a product with higher purity.

[0016] The invention relates to an application of the chitosan oligosaccharide derivative as a perfume fixative.

[0017] The preparation process of perfume can be but not limited to the following: Take floral water as an example, the following components by volume percentage: 2% lavender oil, 0.8% menthol, 0.4% borneol, 0.3% eugenol, 0.4% fixative, and the balance is 75% alcohol. For the sake of comparison, a formula without fixative is used as a control.

[0018] S1. Add menthol and borneol to container 1 and stir to dissolve with 75% alcohol; S2. Add lavender oil and eugenol to the mixing container 1 and stir to mix; S3. Add the fixative to container 2 and stir to dissolve with 75% alcohol; S4. Mix the solutions in container 1 and container 2 and stir evenly to obtain the finished product of the test toilet water.

[0019] The chitosan oligosaccharide in the present invention is also called chitosan oligosaccharide or low-molecular chitosan, which is obtained by degrading chitosan and has a polymerization degree of 2 to 20 consisting of β-1,4 glycosidic bonds and a molecular weight of ≤3200Da. Due to the rich polar hydroxyl and amino groups in its molecular structure, the chitosan oligosaccharide molecules are endowed with excellent biocompatibility and hydrophilicity. In particular, it has good film-forming properties and good moisturizing properties. When used in cosmetics, it is very friendly to the skin's own ecosystem.

[0020] Due to the rigidity of the molecular structure of chitosan oligosaccharides, they are usually difficult to dissolve in ethanol solutions with high concentrations. In order to improve its solubility in ethanol solutions, a certain amount of hydrophobic groups are introduced into its molecular structure. Since the amino group is more active than the hydroxyl group and is evenly distributed on both sides of the glucose structural unit with larger intervals, if appropriate hydrophobic groups are introduced into the amino group, the entire molecule will be amphiphilic and easy to obtain good dispersibility. In this case, it was found that if an acyl amino acid structure is introduced into the amino group of chitosan oligosaccharides, due to the rigidity of the amino acid peptide bond itself, a "T"-shaped cross is formed in space with the pyran ring structure on the chitosan oligosaccharide chain. This structure can easily form a multi-site molecular action complex with some small molecules. This complex will have the following equilibrium in the solution: (1) The following equilibrium also exists when the monomer in the solution evaporates: (2) Due to the existence of equilibrium (1), the concentration of fragrance monomers in the solution will decrease due to the formation of complexes. Because perfume belongs to a non-ideal liquid phase with low vapor pressure, according to the modified Raoult's law (the vapor pressure of the volatile components in the gas phase is proportional to the concentration (or activity) of the components in the solution), the vapor pressure of the fragrance components volatilized to the gas phase decreases, thereby extending the volatilization time of the fragrance components in the perfume, thereby achieving the effect of fixing the fragrance.

[0021] Cinnamic acid is widely used in cosmetics as a fragrance additive, sunscreen, preservative, antioxidant, and whitening agent, but it is rarely used directly in perfumes (ethyl cinnamate is the most common in perfumes). Since the carbonyl group in the molecular structure of cinnamic acid can form a conjugated system with the connected carbon-carbon double bond and benzene ring, the entire molecule can remain in a plane. When cinnamic acid is coupled to the amino group of an amino acid, this planar structure will not hinder the polar groups of small molecules from approaching the "T"-shaped structure part on the chitosan oligosaccharide due to the folding of the molecule, and because of the greater hydrophobicity of the terminal benzene ring, the lipophilicity of the chitosan oligosaccharide derivative is greatly improved. When enough cinnamoyl amino acids are coupled to the chitosan oligosaccharide molecular structure, the chitosan oligosaccharide derivative can have sufficient solubility in ethanol solution. However, too many cinnamoyl groups will greatly reduce the water solubility of the entire chitosan oligosaccharide derivative, affecting its hydrophilic properties. In view of this, in order to make the chitosan oligosaccharide molecules both soluble in ethanol solution and sufficiently hydrophilic (for moisturizing), a hybrid mode is used in molecular design, that is, cinnamic acid amino acids (about 70%) are introduced to the amino groups of the chitosan oligosaccharide molecules, and acetyl amino acids (about 30%) with relatively low hydrophobicity are introduced to the remaining amino groups. The molecular structure formed in this way can have both hydrophobicity and hydrophilicity, and the small peptide chain formed on the molecular structure is very conducive to moisturizing water molecules. In addition, since the antibacterial property of cinnamic acid is mainly caused by the insertion of the hydrophobic benzene ring end into the hydrophobic cell membrane (affecting the permeability of the membrane and the activity of the enzyme), it can also give the corresponding derivatives antibacterial properties after coupling to chitosan oligosaccharides.

[0022] Regarding the selection of suitable amino acids, since it does not need to have very strong specificity with the fragrance molecule in the design structure, glycine with the simplest structure can be used as the raw material. On the one hand, it can reduce the production cost. On the other hand, the coupling of carboxyl and amino groups can adopt a method suitable for large-scale synthesis: the pivaloyl chloride method.

[0023] Carboxylic acid reacts with pivaloyl chloride to generate the corresponding carboxylic acid - pivalic anhydride. From the molecular structure of the anhydride, due to the steric hindrance and electron-donating effect of the tert-butyl group, the reactivity of the nucleophilic reaction on the carbonyl carbon atom of the anhydride connected to the tert-butyl group is low, so the amino group mainly attacks the other carbonyl carbon atom of the anhydride (i.e., the carbonyl carbon atom at the end of the amino acid); due to the high activity of the anhydride, the coupling efficiency is also high.

[0024] Compared with other amino acids, the side chain residues cause certain steric hindrance, especially if the acyl group at the N-terminus of the amino acid forms a large steric hindrance effect, the efficiency of coupling between the carboxylic acid end and the amino group is low. Therefore, glycine was selected as the supporting amino acid in this case.

[0025] When the chitosan oligosaccharide derivative is used as a fixative to prepare floral water and sprayed on the skin, since it is not volatile, after the volatile substances evaporate, they will remain on the skin surface to form a thin layer. The N-terminal styrene group in its molecular structure has a good ability to absorb free radicals, so it can obtain a certain anti-ultraviolet radiation effect; the hydrophobicity of the styrene group has good compatibility with sebum, so this residue can be well dispersed on the surface of the skin, and the concentration after precipitation is relatively high, so it has good antibacterial properties; in addition, the presence of the polyhydroxy structure on the pyranose ring and the small peptide chain of the side chain can lock part of the moisture, so it can form a certain "enriched" moisture protective "film" on the skin surface, which is very beneficial to skin moisturizing. Because it can form hydrogen bonds with the polar groups of the fragrance molecules, it can prevent their volatilization rate, which is equivalent to "adhering" these fragrance molecules to the skin, thereby prolonging the fragrance retention time and playing the role of a fixative.

[0026] Compared with the prior art, the present invention has the following beneficial effects: This case is the first to use chitosan oligosaccharides as raw materials to design and synthesize a perfume fixative with multiple functions such as antibacterial, moisturizing, and good biocompatibility. The synthesis reaction time is short and the yield is high, avoiding the use of high-cost reaction reagents (such as N-hydroxysuccinimide, dicyclohexylcarbodiimide (DCC), ethyl [3-(dimethylamino)propyl] carbodiimide hydrochloride (EDAC)), etc.). The reaction can be quantified and can be industrialized. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the H NMR spectrum of cinnamoylglycine prepared in Example 1.

[0028] Figure 2 This is the C NMR spectrum of cinnamoylglycine prepared in Example 1.

[0029] Figure 3 This is the infrared spectrum of C(A)GCO prepared in Example 1.

[0030] Figure 4 This is the UV test spectrum of C(A)GCO prepared in Example 1 (the concentration is 72 μg / mL).

[0031] Figure 5 This is a comparison chart of the antibacterial effects of the prepared C(A)GCO at a concentration of 60 mg / mL; A: Staphylococcus aureus; B: Escherichia coli.

[0032] Figure 6 This is a graph of the volatility in the first half hour at different C(A)GCO addition ratios.

[0033] Figure 7 This is the residual amount of the solution after continuous volatilization when the addition amount of C(A)GCO is 0.4%.

[0034] Figure 8 This is a chart showing the residual amount of the prepared floral water after continuous evaporation.

[0035] Fig. 9 These are pictures showing the effects of the finished floral water and the reference product after being tried on simulated skin, where A: reference product; B: finished product. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] Embodiment 1: The molecular reaction formula for synthesizing chitosan oligosaccharide derivatives is as follows: Among them, n=2~6.

[0039] Step 1) Dissolve 150 mg of glycine and 212 mg of sodium carbonate in an appropriate amount of deionized water, cool to 0°C, add 10 mL of DMF solution containing 341 mg of cinnamoyl chloride dropwise, and stir for 2 to 4 hours to complete the reaction. Acidify with concentrated hydrochloric acid to pH = 1 to 2, then extract with 5 mL of ethyl acetate three times, wash and add anhydrous sodium sulfate to dry for 4 to 6 hours; filter to remove the desiccant, and rotary evaporate the filtrate to obtain a white solid product, cinnamoyl glycine; Characterized by NMR, H spectrum (see attached Figure 1 ) and carbon spectrum (attached Figure 2 ) The results are as follows: 1H NMR (400 MHz, DMSO-d6) δ12.52 (s, 1H), 8.42 (t, J = 6.0 Hz, 1H), 7.58 (d, J = 6.7 Hz, 2H), 7.48-7.36 (m,4H), 6.73 (d, J = 15.8 Hz, 1H), 3.90 (d, J = 5.9 Hz, 2H); 13C NMR (100 MHz, DMSO-d6) δ 171.33, 165.28, 139.20, 134.80, 129.56, 128.96, 127.59,121.68, 40.83.

[0040] Step 2) Dissolve 70 mg of acetylglycine and 287 mg of the product of step 1) in 8 ml of DMF, add 287 μL of triethylamine, cool to 0°C, add 254 μL of pivaloyl chloride solution dropwise, gradually warm to room temperature and react for 2 h, filter to remove the white precipitate, and obtain a mixed anhydride solution; Step 3) Weigh 322 mg of chitosan oligosaccharide and 212 mg of sodium carbonate and dissolve them in a certain amount of deionized water, add the mixed anhydride solution obtained in step 2) dropwise, react for 3-4 hours, filter the reaction solution, precipitate and filter with n-propanol, concentrate the centrifuged liquid to 1 / 4, precipitate the filtrate with ethyl acetate after filtration, centrifuge and vacuum dry to obtain the chitosan oligosaccharide derivative.

[0041] According to elemental analysis, the content of each element is: C56.8%, N9.6%, O33.6%, which is basically consistent with the theoretical results (C57.6%, N9.2%, O33.2%).

[0042] The infrared spectrum of C(A)GCO prepared by this method is shown in the attached figure. Figure 3 shown.

[0043] In the attached Figure 3 The broad peak near 3294 cm-1 is mainly the stretching vibration peak of OH on the hydroxyl group and NH on the amide group on glucosamine, and the absorption near 2930 cm-1~2810 cm-1 is the stretching vibration peak of the CH bond on the carbon-carbon double bond; the absorption at 1632 cm-1~1597 cm-1 is mainly the conjugation of the stretching vibration peak of the amide bond and the characteristic absorption peak of the benzene ring skeleton vibration.

[0044] The UV spectra of C(A)GCO and raw chitosan oligosaccharide (CO) prepared by this method are shown in the attached figure. Figure 4 As shown in the figure, the raw chitosan oligosaccharide has almost no absorption peak in the wavelength range of 200 nm – 400 nm, and after the reaction, there are obvious absorption peaks at 218 nm and 280 nm. The peak shape is similar to the ultraviolet spectrum of cinnamic acid in the literature, indicating the presence of cinnamoyl groups in the product.

[0045] Attached Figure 5 The following is a picture showing the inhibitory effect of the prepared C(A)GCO on the culture of Escherichia coli and Staphylococcus aureus at a concentration of 60 mg / mL (Oxford cup method). Figure 5It can be seen that C(A)GCO forms obvious inhibition zones or rings (both with diameters greater than 7 mm) for both bacteria at the action concentration, among which the inhibition zone for Staphylococcus aureus is larger than that for Escherichia coli, indicating that C(A)GCO has significant antibacterial effects on both bacteria. The reason for the formation of the inhibition zone for Staphylococcus aureus may be that the C(A)GCO sample solution is added to the Oxford cup, and C(A)GCO produces a diffusion effect on the culture medium. Since the derivatives are composed of oligomers of different molecular weights, oligomers with small molecular weight diffuse faster, while those with large molecular weight diffuse relatively slowly. Oligomers with small molecular weight bind to bacteria in large numbers and have good antibacterial effects, while oligomers with large molecular weight bind to bacteria less and have poor antibacterial effects. There are still oligomers with high concentrations that have not diffused in the Oxford cup, so the Oxford cup also produces an antibacterial effect.

[0046] Embodiment 2: In order to find out the formula ratio of the present invention for perfume, the method is as follows.

[0047] Different concentrations (0.2%, 0.3%, 0.4%, 0.5%, 0.6%) of fixative solutions were prepared with 75% ethanol solution, 200 μL of the solution was absorbed on a solid surface of a fixed area, and its volatility was measured every 0.5 h at room temperature. Figure 6 ).

[0048] By the attached Figure 6 It can be seen that with the increase in the amount of C(A)GCO added, the volatilization amount in the first half hour gradually decreases, and reaches the lowest value when the addition ratio reaches 0.4%. This is related to the colligative properties of dilute solutions, that is, the vapor pressure of the solution decreases with the increase of solute concentration, resulting in a decrease in the volatilization rate; when the addition ratio exceeds 0.4%, the volatilization amount of the solution gradually increases. This may be because C(A)GCO can bind to water molecules. When the amount of water molecules bound by C(A)GCO is large, the ethanol content in the solution increases, causing the volatilization rate to accelerate. Therefore, the amount of fixative added to the 75% ethanol solution is 0.4%. The continuous measurement value of the volatile residual amount of the solution at this ratio is shown in the attached figure. Figure 7 shown.

[0049] By the attached Figure 7 It can be seen that under the same conditions, the evaporation rate of 0.4% C(A)GCO solution is significantly lower than that of 75% ethanol solution. The 75% ethanol solution evaporates completely in 2.5 hours at room temperature, while the corresponding evaporation time of 0.4% C(A)GCO solution is 3.5 hours, and the final residual amount is about 0.07 mg.

[0050] Example 3 The present invention can be used for preparing perfume, and the method is as follows.

[0051] S1. Add 320 mg of menthol and 160 mg of borneol to container 1 and stir to dissolve with 10 mL of 75% alcohol (prepared with cosmetic grade anhydrous ethanol and deionized water); S2. 800 mg of lavender oil and 120 mg of eugenol were added to the mixing container 1 and stirred to mix; S3. Add 40 mg of fixative to container 2 and dissolve with 5 mL of 75% alcohol (same as ethanol in S1); S4. Take 5 mL of the solution in container 1 and add it to the solution in container 2. Stir well to obtain the finished product of the test toilet water. Add 5 mL of 75% alcohol to the remaining solution in container 1 and stir well to serve as the control.

[0052] In order to test the volatility of prepared floral water, the method is as follows.

[0053] Take 120 μL of the test floral water product and the reference product respectively on a fixed area of ​​solid surface, and measure their volatilization amount every 0.5 h at room temperature. The volatile residual amount of the two samples is continuously measured as shown in the attached figure. Figure 8 shown.

[0054] By the attached Figure 8 It can be seen that the reference product evaporates faster in the first 3 hours, and the residual amount is smaller. The two reach the same residual amount around 3 hours, and between 3 hours and 4 hours, the two have similar volatilization speeds and the residual amounts are almost the same. After 4 hours, the volatilization speed of the finished product is faster than that of the reference product, and the residual amount is correspondingly smaller. Because the slope of the graph represents the volatilization speed, it is not difficult to see that in the first hour, both have a larger volatilization speed, and after 1 hour, the volatilization speeds of both decrease sharply; between 1 hour and 4 hours, the volatilization speed of the finished product is relatively uniform, while the volatilization speed of the reference product shows a slowly decreasing process, indicating that the present invention has a significant improvement effect on the volatility of the floral water. After 4.5 hours, the slope of the residual curve of the finished product is gentler than that of the reference product, achieving a sustained release effect, so the fragrance of the test floral water product can last up to 48 hours, and the duration of the reference product is 20 hours.

[0055] Attached Fig. 9 The following are the effects of the two products after being tried on simulated skin. As can be seen from the figure, after the control product is tried, the simulated skin surface is dry, while after the finished product is tried, a "wet layer" remains on the surface. Obviously, this "wet layer" is the residue of the present invention. Due to its good dispersibility, it forms a "protective film" on the surface of the simulated skin, which can not only retain some moisture, but also hinder the evaporation of skin moisture, thereby achieving a moisturizing effect. Since the concentration of the precipitated solids has far exceeded the antibacterial concentration, this "protective film" has a strong antibacterial ability.

[0056] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A chitosan oligosaccharide derivative having aroma-fixing and antibacterial functions, characterized in that: Its molecular structure is as follows: Among them, n=2~6.

2. A method for preparing a chitosan oligosaccharide derivative as claimed in claim 1, characterized in that: The following steps are involved: Step 1) dissolve glycine and sodium carbonate in deionized water, cool to 0°C, add DMF solution of cinnamoyl chloride dropwise, stir for 2-4 h to complete the reaction; acidify with concentrated hydrochloric acid to pH = 1-2, then extract and wash with an equal amount of ethyl acetate, add anhydrous sodium sulfate and dry for 4-6 h; filter to remove the desiccant, and rotary evaporate the filtrate to obtain a white solid product cinnamoyl glycine; Step 2) dissolving acetylglycine and the product obtained in step 1) in DMF to obtain a DMF mixed solution, adding triethylamine, cooling to 0°C, adding an equivalent amount of pivaloyl chloride solution dropwise, gradually heating to room temperature and reacting for 2h, filtering to remove the white precipitate, and obtaining a mixed anhydride solution; Step 3) weigh appropriate amounts of chitosan oligosaccharide and sodium carbonate and dissolve them in a certain amount of deionized water, add the mixed anhydride solution obtained in step 2) dropwise, react for 3-4 hours, filter the reaction solution, precipitate with n-propanol and centrifuge, concentrate the centrifuge to 1 / 4, filter the filtrate and precipitate with solvent A, centrifuge and vacuum dry to obtain the chitosan oligosaccharide derivative.

3. The method for preparing the chitosan oligosaccharide derivative according to claim 2, characterized in that: The molar ratio of the raw materials in step 1) is: glycine: sodium carbonate: cinnamoyl chloride = 1: 1.1-1.3: 1.1-1.

4.

4. The method for preparing the chitosan oligosaccharide derivative according to claim 2, characterized in that: The molar ratio of the raw materials in step 2) is: acetylglycine: cinnamoylglycine = 1: 1-3.

5. The method for preparing the chitosan oligosaccharide derivative according to claim 2, characterized in that: The molar ratio of the raw materials in step 2) is: DMF mixed solution: triethylamine: pivaloyl chloride = 1: 1.0-1.05: 1.0-1.

05.

6. The method for preparing the chitosan oligosaccharide derivative according to claim 2, characterized in that: The molar ratio of the raw materials in step 3) is: mixed anhydride solution: sodium carbonate: chitosan oligosaccharide = 1: 1.0-1.05: 0.9-1.

05.

7. The method for preparing the chitosan oligosaccharide derivative according to claim 2, characterized in that: The solvent A used in step 3) is selected from tetrahydrofuran, ethyl acetate or propyl acetate.

8. Use of the chitosan oligosaccharide derivative as claimed in claim 1 as a perfume fixative.

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