An N-carboxymethyl chitosan quinolone derivative, its preparation method and application

Abstract

The present invention belongs to the fields of medicine and agriculture, and particularly relates to an N-carboxymethyl chitosan quinolone derivative, a preparation method thereof, and an application thereof. The derivative is a compound shown in Formula I. The preparation method is to prepare N-carboxymethyl chitosan and perform ion exchange with a protonated quinolone compound derivative to obtain the derivative shown in Formula I. The raw materials of this method are cheap and easily available, and the preparation is simple. The chitosan derivative prepared by this method has higher antibacterial activity than chitosan, the reaction conditions are green and harmless, the yield is high, and it can be widely applied in the fields of medicine, agriculture, etc. Formula I.

Description

Technical Field

[0001] The present invention belongs to the fields of medicine and agriculture, and particularly relates to an N-carboxymethyl chitosan quinolone derivative, a preparation method thereof, and an application thereof. Background Art

[0002] Quinolone antibiotics are synthetic antibiotics with a broad antibacterial spectrum and have good bactericidal effects on various bacteria. They are commonly used to treat various bacterial infections in humans and animals, including gastrointestinal infections, respiratory tract infections, skin infections, etc. In addition to the acidic carboxyl group in the quinolone antibiotic structure, there is also a basic nitrogen atom, so the quinolone antibiotic can be protonated to make it carry a positive charge for subsequent derivatization modification.

[0003] Chitosan is the only basic polysaccharide in nature. Its unique molecular structure endows chitosan with diverse biological activities and characteristics, such as antibacterial activity, antioxidant activity, biocompatibility, etc. However, due to the poor biological activity of chitosan, its applications in the fields of medicine and agriculture are limited. Summary of the Invention

[0004] The purpose of the present invention is to provide an N-carboxymethyl chitosan quinolone derivative, a preparation method thereof, and an application thereof.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] An N-carboxymethyl chitosan quinolone derivative, and the derivative is a compound shown in Formula I, Formula I, where R = , , , , ; the average degree of polymerization is 10 - 1242.

[0007] A preparation method of the above-mentioned N-carboxymethyl chitosan quinolone derivative, using chitosan as a raw material, introducing a carboxymethyl group into its structure to obtain N-carboxymethyl chitosan; then performing ion exchange with a protonated quinolone derivative to obtain a derivative shown in Formula I with R being -COO - R-N + .

[0008] The protonated quinolone derivative is a hydrochloride or acetate of a quinolone compound; wherein, the quinolone compound is one or more of levofloxacin, ciprofloxacin, norfloxacin, enoxacin, gatifloxacin, or derivatives corresponding to the foregoing compounds.

[0009] The N-carboxymethyl chitosan undergoes ion exchange with the protonated quinolone derivative, enabling the anions in the N-carboxymethyl chitosan to combine with the cationic groups of the quinolone compound, resulting in the derivative shown in Formula I.

[0010] The N-carboxymethyl chitosan and the protonated quinolone derivative are subjected to a light-avoiding reaction for 10 - 24 h. After the reaction is completed, the reaction product is transferred to a dialysis bag for dialysis for 24 - 48 h, and then freeze-dried for 48 h to obtain the product; the molar ratio of the N-carboxymethyl chitosan to the protonated quinolone compound is 1:3 - 8.

[0011] Furthermore,

[0012] (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan is dissolved in 40 mL of deionized water, 1.15 g of glyoxylic acid is added thereto, and after reacting for 3 h, the pH of the solution is adjusted to about 10 - 12. Then, 0.48 g of sodium borohydride is dissolved in 10 mL of water and added to the above chitosan solution to continue the reaction for 1 h; finally, the product is precipitated and washed with excess absolute ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0013] (2) Preparation of quinolone ion complex chitosan salt derivatives: The N-carboxymethyl chitosan and the protonated quinolone compound are subjected to a light-avoiding reaction for 10 - 24 h. After the reaction is completed, the solution is transferred to a dialysis bag for dialysis for 24 - 48 h, and then freeze-dried for 48 h to obtain the product; the molar ratio of the N-carboxymethyl chitosan to the protonated quinolone compound is 1:3 - 8.

[0014] An application of the N-carboxymethyl chitosan quinolone derivative as described above, the application of the derivative in the preparation of an antibacterial agent.

[0015] Advantages of the present invention:

[0016] The raw materials of the present invention are inexpensive and easily available, and the preparation method is simple. The chitosan derivative prepared by the method of the present invention has higher antibacterial activity than chitosan, the reaction conditions are green and harmless, the yield is high, and it can be widely applied in fields such as medicine and agriculture. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a synthetic route diagram of the quinolone ion complex chitosan salt derivative provided by the embodiment of the present invention.

[0018] Figure 2 It is an infrared spectrum diagram of the chitosan described in Examples 1 - 15 of the present invention: The band at 892 cm -1 belongs to the bending vibration peak of C-O-C within and on the sugar ring, and 1019 cm -1 and 1094 cm -1The nearby spectral band belongs to -OH at positions C3 and C6, 1599 cm -1 The nearby spectral band belongs to the bending vibration peak of -NH2 at position C2, 1643 cm -1 The nearby spectral band belongs to the amide I band absorption peak in the chitosan structure, 3426 cm -1 The nearby spectral band belongs to the stretching vibration peaks of -OH and -NH2.

[0019] Figure 3 This is the infrared spectrogram of N-carboxymethyl chitosan described in Examples 1-15 of the present invention: 3439 cm -1 The characteristic absorption peak at this position is related to the stretching vibrations of -OH and -NH2 in the chitosan structure, 1592 cm -1 The characteristic absorption peak at this position is related to the bending vibration of -NH2. Compared with chitosan, new characteristic peaks appear in the infrared spectrogram of the N-carboxymethyl chitosan quinolone salt derivative: at 1592 cm -1 and 1403 cm -1 The two characteristic absorption peaks are related to the carboxylate group on the N-carboxymethyl chitosan structure. Among them, the absorption peak at 1592 cm -1 merges with the absorption peak of the amino group in the chitosan structure and shows a strong peak.

[0020] Figure 4 This is the infrared spectrogram of the N-carboxymethyl chitosan levofloxacin salt described in Examples 1-3 of the present invention: Compared with chitosan and N-carboxymethyl chitosan, new characteristic absorption peaks appear in the infrared spectrum of the N-carboxymethyl chitosan levofloxacin salt. The absorption peak at 1720 cm -1 is related to the vibration of the free carboxyl group in the quinolone structure; the characteristic absorption peak at 1638 cm -1 is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of C-F in the quinolone structure appears at 1255 cm -1 and new characteristic absorption peaks appear in the fingerprint region of the N-carboxymethyl chitosan levofloxacin salt at 700-900 cm -1

[0021] Figure 5 This is the infrared spectrogram of the N-carboxymethyl chitosan ciprofloxacin salt described in Examples 4-6 of the present invention: Compared with chitosan and N - carboxymethyl chitosan, new characteristic absorption peaks appear in the N-carboxymethyl chitosan ciprofloxacin salt. The absorption peak at 1720 cm -1 is related to the vibration of the free carboxyl group in the quinolone structure; the characteristic absorption peak at 1627 cm -1 is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of C-F in the quinolone structure appears at 1272 cm -1 ​At this point, new characteristic absorption peaks appeared in the fingerprint region of N-carboxymethyl chitosan ciprofloxacin salt at 700-900 cm -1 The fingerprint region showed new characteristic absorption peaks.

[0022] Figure 6 The following is the infrared spectrum of N-carboxymethyl chitosan norfloxacin salt described in Examples 7-9 of the present invention: Compared with chitosan and N-carboxymethyl chitosan, new characteristic absorption peaks appeared in N-carboxymethyl chitosan norfloxacin salt. The absorption peak at 1722 cm -1 is related to the vibration of the free carboxyl group in the quinolone structure; the characteristic absorption peak at 1629 cm -1 is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of C-F in the quinolone structure appears at 1254 cm -1 At this point, new characteristic absorption peaks appeared in the fingerprint region of N-carboxymethyl chitosan norfloxacin salt at 700-900 cm -1 The fingerprint region showed new characteristic absorption peaks.

[0023] Figure 7 The following is the infrared spectrum of N-carboxymethyl chitosan enoxacin salt described in Examples 10-12 of the present invention: Compared with chitosan and N-carboxymethyl chitosan, new characteristic absorption peaks appeared in N-carboxymethyl chitosan enoxacin salt. The absorption peak at 1725 cm -1 is related to the vibration of the free carboxyl group in the quinolone structure; the characteristic absorption peak at 1624 cm -1 is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of C-F in the quinolone structure appears at 1261 cm -1 At this point, new characteristic absorption peaks appeared in the fingerprint region of N-carboxymethyl chitosan enoxacin salt at 700-900 cm -1 The fingerprint region showed new characteristic absorption peaks.

[0024] Figure 8 The following is the infrared spectrum of N-carboxymethyl chitosan gatifloxacin salt described in Examples 13-15 of the present invention: Compared with chitosan and N-carboxymethyl chitosan, new characteristic absorption peaks appeared in N-carboxymethyl chitosan gatifloxacin salt. The absorption peak at 1716 cm -1 is related to the vibration of the free carboxyl group in the quinolone structure; the characteristic absorption peak at 1629 cm -1 is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of C-F in the quinolone structure appears at 1257 cm -1 At this point, new characteristic absorption peaks appeared in the fingerprint region of N-carboxymethyl chitosan gatifloxacin salt at 700-900 cm -1 The fingerprint region showed new characteristic absorption peaks. Detailed implementation mode

[0025] The specific embodiments of the present invention will be further described below in conjunction with examples. It should be noted that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention and are not limited to the present invention. Example 1

[0026] As Figure 1 shown, prepare N-carboxymethyl chitosan levofloxacin salt:

[0027] (1) Preparation of N-carboxymethyl chitosan: First, take 1 g of chitosan and dissolve it in 40 mL of deionized water. Add 1.15 g of glyoxylic acid to it. After reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h. Finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter it to obtain N-carboxymethyl chitosan salt.

[0028] (2) Preparation of N-carboxymethyl chitosan levofloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and weigh 6 mmol of levofloxacin in 15 mL of deionized water. Then add 6 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 24 h under the condition of room temperature and avoiding light. After the reaction is completed, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan levofloxacin salt can be obtained. Example 2

[0029] The difference from Example 1 is as follows:

[0030] As Figure 1 shown, prepare N-carboxymethyl chitosan levofloxacin salt:

[0031] (1) Preparation of N-carboxymethyl chitosan: First, take 1 g of chitosan and dissolve it in 40 mL of deionized water. Add 1.15 g of glyoxylic acid to it. After reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h. Finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter it to obtain N-carboxymethyl chitosan salt.

[0032] (2)Preparation of N-carboxymethyl chitosan levofloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and weigh 10 mmol of levofloxacin in 50 mL of deionized water. Then add 10 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 12 h under room temperature and dark conditions. After the reaction, transfer the reaction solution to a dialysis bag with a cut-off molecular weight of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan levofloxacin salt can be obtained. Example 3

[0033] The difference from Example 2 is that:

[0034] As Figure 1 shown, prepare N-carboxymethyl chitosan levofloxacin salt:

[0035] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0036] (2)Preparation of N-carboxymethyl chitosan levofloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and weigh 16 mmol of levofloxacin in 50 mL of deionized water. Then add 16 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 10 h under room temperature and dark conditions. After the reaction, transfer the reaction solution to a dialysis bag with a cut-off molecular weight of 500 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan levofloxacin salt can be obtained. Example 4

[0037] As Figure 1 shown, prepare N-carboxymethyl chitosan ciprofloxacin salt:

[0038] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0039] (2)Preparation of N-carboxymethyl chitosan ciprofloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 6 mmol of ciprofloxacin in 15 mL of deionized water. Then add 6 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 24 h under the condition of room temperature and avoiding light. After the reaction is completed, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan ciprofloxacin salt can be obtained. Example 5

[0040] The difference from Example 4 is that:

[0041] As Figure 1 shown, prepare N-carboxymethyl chitosan ciprofloxacin salt:

[0042] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0043] (2)Preparation of N-carboxymethyl chitosan ciprofloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 10 mmol of ciprofloxacin in 50 mL of deionized water. Then add 10 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 12 h under the condition of room temperature and avoiding light. After the reaction is completed, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan ciprofloxacin salt can be obtained. Example 6

[0044] The difference from Example 5 is that:

[0045] As Figure 1 shown, prepare N-carboxymethyl chitosan ciprofloxacin salt:

[0046] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0047] (2)Preparation of N-carboxymethyl chitosan ciprofloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 16 mmol of ciprofloxacin in 50 mL of deionized water. Then add 16 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 10 h under dark conditions at room temperature. After the reaction, transfer the reaction solution to a dialysis bag with a cut-off molecular weight of 500 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan ciprofloxacin salt can be obtained. Example 7

[0048] As Figure 1 shown, prepare N-carboxymethyl chitosan norfloxacin salt:

[0049] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0050] (2)Preparation of N-carboxymethyl chitosan norfloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 6 mmol of norfloxacin in 15 mL of deionized water. Then add 6 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 24 h under dark conditions at room temperature. After the reaction, transfer the reaction solution to a dialysis bag with a cut-off molecular weight of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan norfloxacin salt can be obtained. Example 8

[0051] The difference from Example 7 is that:

[0052] As Figure 1 shown, prepare N-carboxymethyl chitosan norfloxacin salt:

[0053] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0054] (2)Preparation of N-carboxymethyl chitosan norfloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 1 mL of deionized water, and weigh 10 mmol of norfloxacin in 50 mL of deionized water. Then add 10 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 12 h under room temperature and dark conditions. After the reaction, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan norfloxacin salt can be obtained. Example 9

[0055] The difference from Example 8 is that:

[0056] As Figure 1 shown, prepare N-carboxymethyl chitosan norfloxacin salt:

[0057] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0058] (2)Preparation of N-carboxymethyl chitosan norfloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and weigh 16 mmol of norfloxacin in 50 mL of deionized water. Then add 16 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 10 h under room temperature and dark conditions. After the reaction, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 500 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan norfloxacin salt can be obtained. Example 10

[0059] As Figure 1 shown, prepare N-carboxymethyl chitosan enoxacin salt:

[0060] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0061] (2)Preparation of N - carboxymethyl chitosan enoxacin salt: Weigh 2 mmol of N - carboxymethyl chitosan in 15 mL of deionized water, and then weigh 6 mmol of enoxacin in 15 mL of deionized water. Then add 6 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 24 h under the condition of room temperature and avoiding light. After the reaction, transfer the reaction solution into a dialysis bag with a cut - off molecular weight of 100 g / mol and dialyze for 48 h, and then freeze - dry for 48 h to obtain N - carboxymethyl chitosan enoxacin salt. Example 11

[0062] The difference from Example 10 is that:

[0063] As Figure 1 shown, prepare N - carboxymethyl chitosan enoxacin salt:

[0064] (1)Preparation of N - carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive anhydrous ethanol or acetone, and filter to obtain N - carboxymethyl chitosan salt.

[0065] (2)Preparation of N - carboxymethyl chitosan enoxacin salt: Weigh 2 mmol of N - carboxymethyl chitosan in 15 mL of deionized water, and then weigh 10 mmol of enoxacin in 50 mL of deionized water. Then add 10 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 12 h under the condition of room temperature and avoiding light. After the reaction, transfer the reaction solution into a dialysis bag with a cut - off molecular weight of 100 g / mol and dialyze for 48 h, and then freeze - dry for 48 h to obtain N - carboxymethyl chitosan enoxacin salt. Example 12

[0066] The difference from Example 11 is that:

[0067] As Figure 1 shown, prepare N - carboxymethyl chitosan enoxacin salt:

[0068] (1)Preparation of N - carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive anhydrous ethanol or acetone, and filter to obtain N - carboxymethyl chitosan salt.

[0069] (2) Preparation of N-carboxymethyl chitosan enoxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 16 mmol of enoxacin in 50 mL of deionized water. Then add 16 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 10 h under room temperature and dark conditions. After the reaction is completed, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 500 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan enoxacin salt can be obtained. Example 13

[0070] As Figure 1 shown, prepare N-carboxymethyl chitosan enoxacin salt:

[0071] (1) Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excess absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0072] (2) Preparation of N-carboxymethyl chitosan gatifloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 6 mmol of gatifloxacin in 15 mL of deionized water. Then add 6 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 24 h under room temperature and dark conditions. After the reaction is completed, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan gatifloxacin salt can be obtained. Example 14

[0073] The difference from Example 13 is that:

[0074] As Figure 1 shown, prepare N-carboxymethyl chitosan gatifloxacin salt:

[0075] (1) Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excess absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0076] (2)Preparation of N-carboxymethyl chitosan gatifloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 10 mmol of enoxacin in 50 mL of deionized water. Then add 10 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 12 h under dark conditions at room temperature. After the reaction, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 100 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan gatifloxacin salt can be obtained. Example 15

[0077] The difference from Example 14 is as follows:

[0078] As Figure 1 shown, prepare N-carboxymethyl chitosan gatifloxacin salt:

[0079] (1)Preparation of N-carboxymethyl chitosan: First, dissolve 1 g of chitosan in 40 mL of deionized water, add 1.15 g of glyoxylic acid to it, and after reacting for 3 h, adjust the pH of the solution to about 10 - 12. Then dissolve 0.48 g of sodium borohydride in 10 mL of water and add it to the above chitosan solution to continue reacting for 1 h; finally, precipitate and wash the product with excessive absolute ethanol or acetone, and filter to obtain N-carboxymethyl chitosan salt.

[0080] (2)Preparation of N-carboxymethyl chitosan gatifloxacin salt: Weigh 2 mmol of N-carboxymethyl chitosan in 15 mL of deionized water, and then weigh 16 mmol of gatifloxacin in 50 mL of deionized water. Then add 16 mmol of solid sodium hydroxide and stir to dissolve. Slowly add the latter solution to the former, and react for 10 h under dark conditions at room temperature. After the reaction, transfer the reaction solution to a dialysis bag with a molecular weight cut-off of 500 g / mol and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan gatifloxacin salt can be obtained.

[0081] Application Example 1

[0082] (1)Determination of antibacterial activity

[0083] The tested bacterial strains are Escherichia coli ( Escherichia coli, E. coli ), Staphylococcus aureus ( Staphylococcus aureus, S. aureus ). Draw 200 μL of bacterial liquid and activate it in a liquid medium for 18 h. Pick a single colony and culture it in a liquid medium until the logarithmic phase for subsequent experiments.

[0084] Preparation of the liquid medium: Accurately weigh 5.0 g of tryptone, 2.5 g of yeast extract, and 5.0 g of sodium chloride, add deionized water to dissolve and make up the volume to 500.0 mL. Sterilize the liquid medium in an autoclave at 121 °C for 20 min, and cool it to room temperature for rejuvenation.

[0085] Preparation of sample solution: Accurately weigh 32 mg of chitosan and the chitosan quinolone derivatives prepared in each of the above examples as samples. After dissolving them in 2 mL of deionized water, a sample solution with a concentration of 16 mg / mL is obtained. Place it in a laminar flow hood, sterilize it, and set aside for use.

[0086] Broth dilution method: Add 100 μL of sterile deionized water to each well of a 96-well plate in a laminar flow hood. Then add 100 μL of the sample solution to the first well of each row in the 96-well plate, and then perform serial dilution of the sample in each row. Finally, add 100 μL of the bacterial suspension to each well. Control the final concentration of the sample to be 8×10 3 ,4×10 3 ,2×10 3 ,1×10 3 ,5×10 2 ,2.5×10 2 ,1.25×10 2 ,62.5, 31.25, 15.625, 7.8125, 3.90625, 1.953125, 0.97656, 0.48828, 0.24414, 0.12207, 0.06104, 0.03052, 0.01526 μg / mL. After culturing for 24 h, observe the growth of bacteria in the 96-well plate. The lowest concentration at which the medium is clear and no bacteria are visible to the naked eye is the minimum inhibitory concentration (MIC) of the chitosan derivative; in the laminar flow hood, pipette 5 μL of the bacterial suspension from the experimental wells without bacterial growth in the 96-well plate and streak it onto a new solid medium for further culturing to further determine the minimum bactericidal concentration (MBC) of the drug. Usually, each compound is repeated 3 times for the experiment.

[0087] (2) Results of antibacterial activity determination

[0088] Table 1 Antibacterial activities of chitosan and N-carboxymethyl chitosan quinolone derivatives

[0089]

[0090] The antibacterial activities of the synthesized N-carboxymethyl chitosan and N-carboxymethyl chitosan quinolone salts of the present invention are shown in Table 1. The experimental results show that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of chitosan against both types of bacteria are greater than 8000 μg / mL, and the antibacterial activities of N-carboxymethyl chitosan quinolone salts are significantly improved compared with chitosan. Among them, the MIC of levofloxacin salt of N-carboxymethyl chitosan against Escherichia coli is 125 μg / mL, MBC is 125 μg / mL, the MIC against Staphylococcus aureus is 31.25 μg / mL, and MBC is 62.50 μg / mL; the MIC of ciprofloxacin salt of N-carboxymethyl chitosan against Escherichia coli is 0.5000 μg / mL, MBC is 1.000 μg / mL, the MIC against Staphylococcus aureus is 7.8125 μg / mL, and MBC is 7.8125 μg / mL; the MIC of norfloxacin salt of N-carboxymethyl chitosan is 7.8125 μg / mL, MBC is 15.625 μg / mL, the MIC against Staphylococcus aureus is 31.25 μg / mL, and MBC is 125.0 μg / mL; the MIC of enoxacin salt of N-carboxymethyl chitosan against Escherichia coli is 1.953125 μg / mL, MBC is 1.953125 μg / mL, the MIC against Staphylococcus aureus is 1.953125 μg / mL, and MBC is 1.953125 μg / mL; the MIC of gatifloxacin salt of N-carboxymethyl chitosan against Escherichia coli is 1.953125 μg / mL, MBC is 1.953125 μg / mL, the MIC against Staphylococcus aureus is 1.953125 μg / mL, and MBC is 1.953125 μg / mL.

[0091] The results of the application examples are analyzed, and the conclusion is drawn that the self-antibacterial activities of chitosan and N-carboxymethyl chitosan are poor, and the MIC and MBC against both types of bacteria are greater than 8000 μg / mL. When N-carboxymethyl chitosan is grafted with quinolone derivatives through ionic bonds, the antibacterial activities of the obtained N-carboxymethyl chitosan quinolone derivatives are significantly improved. The derivatives synthesized in the present invention have obvious inhibitory effects on the growth and reproduction of Escherichia coli and Staphylococcus aureus, and N-carboxymethyl chitosan quinolone derivatives have great application prospects and research values in the fields of medicine and agriculture.

Claims

1. An N-carboxymethyl chitosan quinolone derivative, characterized in that: The derivative is a compound represented by Formula I, Formula I, wherein R = , , , , ; the average value of the degree of polymerization is 10 to 1242.

2. A preparation method of the N-carboxymethyl chitosan quinolone derivative according to claim 1, characterized in that: Using chitosan as a raw material, a carboxymethyl group is introduced into its structure to obtain N-carboxymethyl chitosan; then it is subjected to ion exchange with a protonated quinolone derivative to obtain the derivative shown in Formula I.

3. The preparation method of the N-carboxymethyl chitosan quinolone derivative according to claim 2, characterized in that: The protonated quinolone derivative is a hydrochloride or acetate salt of a quinolone compound; among them, the quinolone compound is one of levofloxacin, ciprofloxacin, norfloxacin, enoxacin, gatifloxacin or a derivative corresponding to the aforementioned compound.

4. The preparation method of the N-carboxymethyl chitosan quinolone derivative according to claim 2 or 3, characterized in that: The N-carboxymethyl chitosan is subjected to ion exchange with the protonated quinolone derivative, so that the anion in the N-carboxymethyl chitosan combines with the cationic group of the quinolone compound to obtain the derivative shown in Formula I.

5. The preparation method of the N-carboxymethyl chitosan quinolone derivative according to claim 4, characterized in that: The N-carboxymethyl chitosan and the protonated quinolone derivative are reacted in the dark for 10-24 h. After the reaction is completed, the reaction product is transferred to a dialysis bag for dialysis for 24-48 h, and then freeze-dried for 48 h to obtain the product; the molar ratio of the N-carboxymethyl chitosan to the protonated quinolone compound is 1:3-8.

6. Use of the N-carboxymethyl chitosan quinolone derivative according to claim 1, characterized in that: Application of the derivative in the preparation of an antibacterial agent.

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