N-carboxymethyl chitosan quinolone derivative as well as preparation method and application thereof

Abstract

The invention belongs to the field of medicine and agriculture, and particularly relates to an N-carboxymethyl chitosan quinolone derivative as well as a preparation method and application thereof. The derivative is a compound as shown in a formula I. The preparation method comprises the following steps: preparing N-carboxymethyl chitosan, and carrying out ion exchange on the N-carboxymethyl chitosan and a protonated quinolone compound derivative to obtain the derivative as shown in the formula I. The method has the advantages of cheap and easily available raw materials and simple preparation. The antibacterial activity of the chitosan derivative prepared by the method is higher than that of chitosan, the reaction conditions are green and harmless, the yield is high, and the chitosan derivative can be widely applied to the fields of medicines, agriculture and the like. And the # imgabs0 # is shown in the formula 1.

Description

Technical Field

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

[0002] Quinolone antibiotics (Quinolones) are synthetic antibiotics with a broad antibacterial spectrum and good killing effects on a variety of bacteria. They are often used to treat various bacterial infections in humans and animals, including gastrointestinal infections, respiratory infections, skin infections, etc. In addition to the acidic carboxyl group, the structure of quinolone antibiotics also contains basic nitrogen atoms, so quinolone antibiotics can be protonated to carry a positive charge for subsequent derivatization modification.

[0003] Chitosan is the only alkaline polysaccharide in nature. Its unique molecular structure gives chitosan a variety of biological activities and characteristics, such as antibacterial activity, antioxidant activity, biocompatibility, etc. However, due to its poor biological activity, chitosan has limited applications in the fields of medicine and agriculture. Summary of the invention

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

[0005] To achieve the above object, the technical solution adopted by the present invention is: An N-carboxymethyl chitosan quinolone derivative, the derivative is a compound shown in formula 1, Formula 1, where R= , , , , ; The average degree of polymerization is 10~1242.

[0006] A method for preparing N-carboxymethyl chitosan quinolone derivatives, using chitosan as a raw material, introducing a carboxymethyl group into its structure to obtain N-carboxymethyl chitosan; then subjecting it to ion exchange with a protonated quinolone derivative to obtain a protonated quinolone derivative having R as -COO - RN + The derivative shown in formula 1.

[0007] 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 aforementioned compounds.

[0008] The N-carboxymethyl chitosan is subjected to ion exchange with the protonated quinolone derivatives, so that the anions in the N-carboxymethyl chitosan are combined with the cationic groups of the quinolone compounds to obtain the derivatives shown in formula 1.

[0009] The N-carboxymethyl chitosan and the protonated quinolone derivatives are reacted in the dark for 10-24 hours. After the reaction is completed, the reaction product is transferred to a dialysis bag and dialyzed for 24-48 hours. The product can be obtained after freeze-drying for 48 hours. The molar ratio of the N-carboxymethyl chitosan to the protonated quinolone compound is 1:3-8.

[0010] Furthermore, (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0011] (2) Preparation of quinolone ion complex chitosan salt derivatives: N-carboxymethyl chitosan and protonated quinolone compounds are reacted in the dark for 10-24 hours. After the reaction is completed, the solution is transferred to a dialysis bag and dialyzed for 24-48 hours. The product can be obtained after freeze-drying for 48 hours. The molar ratio of N-carboxymethyl chitosan to protonated quinolone compounds is 1:3~8.

[0012] An application of the N-carboxymethyl chitosan quinolone derivatives, and an application of the derivatives in the preparation of antibacterial agents.

[0013] The advantages of the present invention are: The raw materials of the invention are cheap and easy to obtain, and the preparation method is simple. The chitosan derivative prepared by the method of the invention has higher antibacterial activity than chitosan, the reaction conditions are green and harmless, the yield is high, and it can be widely used in the fields of medicine, agriculture, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The synthetic route of the quinolone ion complex chitosan salt derivative provided in the embodiment of the present invention.

[0015] Figure 2 The infrared spectrum of chitosan described in Examples 1-15 of the present invention is: 892 cm -1 The band at 1019 cm is attributed to the bending vibration peak of COC in and on the sugar ring. -1 and 1094cm -1 The nearby bands are attributed to -OH at C3 and C6, 1599cm -1The nearby bands are assigned to C2-NH 2 Bending vibration peak, 1643cm -1 The nearby bands are attributed to the amide I band absorption peak in the chitosan structure, 3426 cm -1 The nearby bands are attributed to -OH and -NH 2 Stretching vibration peak.

[0016] Figure 3 Infrared spectrum of N-carboxymethyl chitosan described in Example 1-15 of the present invention: 3439cm -1 The characteristic absorption peak at the chitosan structure is related to the -OH and -NH 2 The stretching vibration of 1592 cm -1 The characteristic absorption peak at -NH 2 Compared with chitosan, a new characteristic peak appeared in the infrared spectrum of N-carboxymethyl chitosan quinolone salt derivative: -1 and 1403cm -1 The two characteristic absorption peaks are related to the carboxylate groups on the structure of N-carboxymethyl chitosan. -1 The absorption peak at is combined with the absorption peak of the amino group in the chitosan structure to show a strong peak.

[0017] Figure 4 The infrared spectrum of N-carboxymethyl chitosan levofloxacin salt described in Example 1-3 of the present invention is as follows: Compared with chitosan and N-carboxymethyl chitosan, the infrared spectrum of N-carboxymethyl chitosan levofloxacin salt has a new characteristic absorption peak. 1720cm -1 The absorption peak at 1638cm is related to the vibration of the free carboxyl group in the quinolone structure; -1 The characteristic absorption peak at 1255 cm is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of CF in the quinolone structure appears at 1255 cm -1 At 700-900 cm -1 A new characteristic absorption peak appeared in the fingerprint region.

[0018] Figure 5 The infrared spectrum of N-carboxymethyl chitosan ciprofloxacin salt described in Example 4-6 of the present invention is as follows: - Compared with carboxymethyl chitosan, N-carboxymethyl chitosan ciprofloxacin salt showed a new characteristic absorption peak. 1720cm -1 The absorption peak at 1627cm is related to the vibration of the free carboxyl group in the quinolone structure; -1 The characteristic absorption peak at 1272 cm is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of CF in the quinolone structure appears at 1272 cm -1At 700-900 cm -1 A new characteristic absorption peak appeared in the fingerprint region.

[0019] Figure 6 This 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, N-carboxymethyl chitosan norfloxacin salt has a new characteristic absorption peak. 1722cm -1 The absorption peak at 1629cm is related to the vibration of the free carboxyl group in the quinolone structure; -1 The characteristic absorption peak at 1254 cm is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of CF in the quinolone structure appears at 1254 cm -1 At 700-900 cm -1 A new characteristic absorption peak appeared in the fingerprint region.

[0020] Figure 7 This 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, N-carboxymethyl chitosan enoxacin salt has a new characteristic absorption peak. 1725cm -1 The absorption peak at 1624cm is related to the vibration of the free carboxyl group in the quinolone structure; -1 The characteristic absorption peak at 1261 cm is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of CF in the quinolone structure appears at 1261 cm -1 At 700-900 cm -1 A new characteristic absorption peak appeared in the fingerprint region.

[0021] Figure 8 This 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, N-carboxymethyl chitosan gatifloxacin salt has a new characteristic absorption peak. 1716cm -1 The absorption peak at 1629cm is related to the vibration of the free carboxyl group in the quinolone structure; -1 The characteristic absorption peak at 1257 cm is related to the stretching vibration of the carbonyl group (C=O) in the quinolone structure. The stretching vibration peak of CF in the quinolone structure appears at 1257 cm -1 At 700-900 cm -1 A new characteristic absorption peak appeared in the fingerprint region. DETAILED DESCRIPTION

[0022] The specific implementation modes of the present invention are further described below in conjunction with examples. It should be noted that the specific implementation modes described here are only for illustrating and explaining the present invention, and are not limited to the present invention. Example 1

[0023] like Figure 1 As shown, N-carboxymethyl chitosan levofloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0024] (2) Preparation of N-carboxymethyl chitosan levofloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 6 mmol levofloxacin in 15 mL deionized water, then add 6 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 24 hours at room temperature and in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 hours. After freeze drying for 48 hours, N-carboxymethyl chitosan levofloxacin salt can be obtained. Example 2

[0025] The difference from Example 1 is that: like Figure 1 As shown, N-carboxymethyl chitosan levofloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0026] (2) Preparation of N-carboxymethyl chitosan levofloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 10 mmol levofloxacin in 50 mL deionized water, then add 10 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 12 h at room temperature and in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan levofloxacin salt can be obtained. Example 3

[0027] The difference from Example 2 is that: like Figure 1 As shown, N-carboxymethyl chitosan levofloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0028] (2) Preparation of N-carboxymethyl chitosan levofloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 16 mmol levofloxacin in 50 mL deionized water, then add 16 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 10 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 500 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan levofloxacin salt can be obtained. Example 4

[0029] like Figure 1 As shown, N-carboxymethyl chitosan ciprofloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0030] (2) Preparation of N-carboxymethyl chitosan ciprofloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 6 mmol ciprofloxacin in 15 mL deionized water, then add 6 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 24 h at room temperature and in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cut-off) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan ciprofloxacin salt can be obtained. Example 5

[0031] The difference from Example 4 is that: like Figure 1 As shown, N-carboxymethyl chitosan ciprofloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0032] (2) Preparation of N-carboxymethyl chitosan ciprofloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 10 mmol ciprofloxacin in 50 mL deionized water, then add 10 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 12 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan ciprofloxacin salt can be obtained. Example 6

[0033] The difference from Example 5 is that: like Figure 1 As shown, N-carboxymethyl chitosan ciprofloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0034] (2) Preparation of N-carboxymethyl chitosan ciprofloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 16 mmol ciprofloxacin in 50 mL deionized water, then add 16 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 10 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 500 g / mol (molecular weight cut-off) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan ciprofloxacin salt can be obtained. Example 7

[0035] like Figure 1 As shown, N-carboxymethyl chitosan norfloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0036] (2) Preparation of N-carboxymethyl chitosan norfloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 6 mmol norfloxacin in 15 mL deionized water, then add 6 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react at room temperature in the dark for 24 hours. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cut-off) dialysis bag and dialyze for 48 hours. After freeze-drying for 48 hours, N-carboxymethyl chitosan norfloxacin salt can be obtained. Example 8

[0037] The difference from Example 7 is that: like Figure 1 As shown, N-carboxymethyl chitosan norfloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0038] (2) Preparation of N-carboxymethyl chitosan norfloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 1 mL of deionized water, weigh 10 mmol of norfloxacin in 50 mL of deionized water, then add 10 mmol of sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 12 h at room temperature and in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cut-off) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan norfloxacin salt can be obtained. Example 9

[0039] The difference from Example 8 is that: like Figure 1 As shown, N-carboxymethyl chitosan norfloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0040] (2) Preparation of N-carboxymethyl chitosan norfloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 16 mmol norfloxacin in 50 mL deionized water, then add 16 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 10 h at room temperature and in the dark. After the reaction is completed, transfer the reaction solution to a 500 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan norfloxacin salt can be obtained. Example 10

[0041] like Figure 1 As shown, N-carboxymethyl chitosan enoxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0042] (2) Preparation of N-carboxymethyl chitosan enoxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 6 mmol enoxacin in 15 mL deionized water, then add 6 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 24 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan enoxacin salt can be obtained. Embodiment 11

[0043] The difference from Example 10 is that: like Figure 1 As shown, N-carboxymethyl chitosan enoxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0044] (2) Preparation of N-carboxymethyl chitosan enoxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 10 mmol enoxacin in 50 mL deionized water, then add 10 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 12 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan enoxacin salt can be obtained. Example 12

[0045] The difference from Example 11 is that: like Figure 1 As shown, N-carboxymethyl chitosan enoxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0046] (2) Preparation of N-carboxymethyl chitosan enoxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 16 mmol enoxacin in 50 mL deionized water, then add 16 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 10 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 500 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan enoxacin salt can be obtained. Example 13

[0047] like Figure 1 As shown, N-carboxymethyl chitosan enoxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0048] (2) Preparation of N-carboxymethyl chitosan gatifloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 6 mmol gatifloxacin in 15 mL deionized water, then add 6 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 24 h at room temperature and in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan gatifloxacin salt can be obtained. Embodiment 14

[0049] The difference from Example 13 is that: like Figure 1 As shown, N-carboxymethyl chitosan gatifloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0050] (2) Preparation of N-carboxymethyl chitosan gatifloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 10 mmol enoxacin in 50 mL deionized water, then add 10 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 12 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 100 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan gatifloxacin salt is obtained. Embodiment 15

[0051] The difference from Example 14 is that: like Figure 1 As shown, N-carboxymethyl chitosan gatifloxacin salt was prepared: (1) Preparation of N-carboxymethyl chitosan: First, 1 g of chitosan was dissolved in 40 mL of deionized water, and 1.15 g of glyoxylic acid was added thereto. After reacting for 3 h, the pH of the solution was adjusted to about 10-12. Then, 0.48 g of sodium borohydride was dissolved in 10 mL of water and added to the chitosan solution to continue reacting for 1 h. Finally, the product was precipitated and washed with excess anhydrous ethanol or acetone, and filtered to obtain N-carboxymethyl chitosan salt.

[0052] (2) Preparation of N-carboxymethyl chitosan gatifloxacin salt: Weigh 2 mmol N-carboxymethyl chitosan in 15 mL deionized water, weigh 16 mmol gatifloxacin in 50 mL deionized water, then add 16 mmol sodium hydroxide solid and stir to dissolve. Slowly add the latter solution to the former and react for 10 h at room temperature in the dark. After the reaction is completed, transfer the reaction solution to a 500 g / mol (molecular weight cutoff) dialysis bag and dialyze for 48 h. After freeze-drying for 48 h, N-carboxymethyl chitosan gatifloxacin salt can be obtained. Application Example 1

[0053] (1) Determination of antibacterial activity The bacterial species tested included Escherichia coli ( Escherichia coli, E. coli ), Staphylococcus aureus ( Staphylococcus aureus, S. aureus ). 200 μL of bacterial culture was extracted and activated in liquid culture medium for 18 h, and a single colony was picked and cultured in liquid culture medium to the logarithmic phase for subsequent experiments.

[0054] Preparation of liquid culture 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 to 500.0 mL. Sterilize the liquid culture medium in an autoclave at 121°C for 20 min, cool to room temperature and use for rejuvenation.

[0055] Preparation of sample solution: accurately weigh 32 mg of chitosan and chitosan quinolone derivatives prepared in the above examples as samples, dissolve them in 2 mL of deionized water to obtain a sample solution with a concentration of 16 mg / mL, place it in a clean bench, sterilize it and set it aside.

[0056] Broth dilution method: Add 100 μL of sterile deionized water to each well of a 96-well plate in a clean bench, then add 100 μL of sample solution to the first well of each row of the 96-well plate, then perform serial dilutions of the sample in each row, and finally add 100 μL of bacterial solution to each well. The final concentration of the control sample is 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, 0.01526μg / mL. After 24 h of culture, the bacterial growth in the 96-well plate was observed. The minimum concentration at which the culture medium was transparent and clear and no bacterial growth was observed by naked eye was the minimum inhibitory concentration (MIC) of the chitosan derivative; in the clean bench, 5μL of bacterial suspension in the experimental wells of sterile growth in the 96-well plate was streaked and inoculated onto a new solid culture medium for further culture to further determine the minimum bactericidal concentration (MBC) of the drug. Usually, the experiment was repeated 3 times for each compound.

[0057] (2) Antibacterial activity test results Table 1 Antibacterial activity of chitosan and N-carboxymethyl chitosan quinolone derivatives

[0058] The antibacterial activities of the N-carboxymethyl chitosan and N-carboxymethyl chitosan quinolone salt synthesized by 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 the two types of bacteria are both greater than 8000 μg / mL, and the antibacterial activity of N-carboxymethyl chitosan quinolone salt is significantly improved compared with chitosan. The MIC of N-carboxymethyl chitosan levofloxacin salt against Escherichia coli was 125 μg / mL, MBC was 125 μg / mL, and the MIC against Staphylococcus aureus was 31.25 μg / mL, MBC was 62.50 μg / mL; the MIC of N-carboxymethyl chitosan ciprofloxacin salt against Escherichia coli was 0.5000 μg / mL, MBC was 1.000 μg / mL, and the MIC against Staphylococcus aureus was 7.8125 μg / mL, MBC was 7.8125 μg / mL; the MIC of N-carboxymethyl chitosan norfloxacin salt was 7.8125 μg / mL, MBC was 15.625 μg / mL, and the MIC against Staphylococcus aureus was The MIC of N-carboxymethyl chitosan enoxacin salt against Escherichia coli is 1.953125μg / mL, MBC is 1.953125μg / mL, and the MIC against Staphylococcus aureus is 1.953125μg / mL, MBC is 1.953125μg / mL; the MIC of N-carboxymethyl chitosan gatifloxacin salt against Escherichia coli is 1.953125μg / mL, MBC is 1.953125μg / mL, and the MIC against Staphylococcus aureus is 1.953125μg / mL, MBC is 1.953125μg / mL.

[0059] The results of the application examples were analyzed, and it was concluded that the antibacterial activity of chitosan and N-carboxymethyl chitosan was poor, and the MIC and MBC of the two bacteria were greater than 8000 μg / mL. When N-carboxymethyl chitosan was grafted with quinolone derivatives through ionic bonds, the antibacterial activity of the obtained N-carboxymethyl chitosan quinolone derivatives was significantly improved. The derivatives synthesized by the present invention have a significant inhibitory effect on the growth and reproduction of Escherichia coli and Staphylococcus aureus, and the N-carboxymethyl chitosan quinolone derivatives have great application prospects and research value in medicine and agriculture.

Claims

1. An N-carboxymethyl chitosan quinolone derivative, characterized in that: The derivative is a compound of formula 1, Formula 1, where R= , , , , ; The average degree of polymerization is 10~1242.

2. A method for preparing the N-carboxymethyl chitosan quinolone derivative according to claim 1, characterized in that: Using chitosan as raw material, carboxymethyl groups were introduced into its structure to obtain N-carboxymethyl chitosan; then it was ion exchanged with protonated quinolone derivatives to obtain R -COO - RN + The derivative shown in formula 1.

3. The method for preparing the N-carboxymethyl chitosan quinolone derivative according to claim 2, characterized in that: 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 aforementioned compounds.

4. The method for preparing 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 derivatives, so that the anions in the N-carboxymethyl chitosan are combined with the cationic groups of the quinolone compounds to obtain the derivatives shown in formula 1.

5. The method for preparing the N-carboxymethyl chitosan quinolone derivative according to claim 4, characterized in that: The N-carboxymethyl chitosan and the protonated quinolone derivatives are reacted in the dark for 10-24 hours. After the reaction is completed, the reaction product is transferred to a dialysis bag and dialyzed for 24-48 hours. The product can be obtained after freeze-drying for 48 hours. The molar ratio of the N-carboxymethyl chitosan to the protonated quinolone compound is 1:3-8.

6. An application of the N-carboxymethyl chitosan quinolone derivative according to claim 1, characterized in that: The derivative is used in preparing an antibacterial agent.

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