Fucoidin improved compound with bacterial targeting property as well as preparation method and application of fucoidin improved compound

Abstract

The invention discloses a fucoidin improved compound with bacterial targeting and a preparation method and application thereof, the compound is a compound of fucoidin and an antibacterial substance, the fucoidin is used as a targeting substance, and an antibacterial drug is modified in a physical coating and chemical connection mode to obtain the fucoidin improved compound; according to the preparation method, fucoidin and an antibacterial substance are synthesized by adopting a one-step method, complicated synthesis conditions such as high temperature, high pressure and pH regulation are not needed, the operation is safe, simple and convenient, and the prepared compound can realize dual targeting of bacteria and inflammation parts, prolong the residence time, effectively relieve inflammation of infected parts and achieve the effect of specific sterilization.

Description

Technical Field

[0001] The present invention relates to a fucoidan complex, in particular to an improved fucoidan complex with bacteria targeting, and also to a preparation method and application of the improved fucoidan complex. Background Art

[0002] Bacterial infections are a major threat to global public health. Diseases such as sepsis, pneumonia, and bacterial gastrointestinal inflammation all originate from bacterial infections, which seriously affect human physical and mental health. Since the discovery of penicillin in 1928, antibiotics have been widely used in medicine and animal husbandry due to their powerful antibacterial properties. However, the widespread and long-term use of antibiotics has led to the emergence of bacterial resistance. With the spread of drug-resistant strains around the world, infections with drug-resistant strains are showing a trend of high morbidity and mortality. Therefore, the development of safe, antibiotic-independent antibacterial strategies to combat bacterial infections is crucial to meeting the challenges of the post-antibiotic era.

[0003] At present, research on alternative therapies for antibiotics includes the development of new small molecule drugs, biological drugs and Chinese herbal extracts. However, the use of these drugs alone still faces the problems of short retention time, poor targeting and inflammatory stimulation, which ultimately leads to the disadvantages of weakened efficacy, destruction of beneficial bacteria and aggravated inflammation, which greatly limits the effectiveness of the drugs.

[0004] Research in recent years has shown that the use of plant-extracted polysaccharide components to treat bacterial infections has become a research hotspot. It has attracted widespread attention due to its natural ingredients, high safety, and certain therapeutic effects. Among them, fucoidan has been proven to have certain antibacterial, anti-inflammatory and immune-enhancing activities. However, in actual use, fucoidan still has defects that cannot be ignored: First, the antibacterial ability of fucoidan is limited. Since the antibacterial properties of fucoidan are mainly achieved by inhibiting the adhesion of bacteria to cells and reducing bacterial colonization, it does not actually cause significant damage to the bacteria themselves, and may even promote bacterial growth as a nutrient. Therefore, the single use of fucoidan cannot achieve the ideal bacterial removal effect; in addition, studies have shown that excessive use of fucoidan can cause side effects including allergic reactions, indigestion, and adverse reactions caused by interactions with other drugs. Therefore, at this stage, fucoidan still exists in the form of health products, and its efficacy cannot be stabilized and used in drug preparation. Therefore, in order to enhance the efficacy and expand its scope of application, further development of fucoidan is urgently needed. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a modified fucoidan complex with bacterial targeting, and also to provide a preparation method and application of the above-mentioned fucoidan complex.

[0006] Technical solution: The present invention discloses a modified fucoidan complex with bacterial targeting, which is a composite of fucoidan and antibacterial substances, with fucoidan as the targeting substance, and is obtained by modifying the antibacterial drug by physical coating and chemical connection.

[0007] The antibacterial substance is antibacterial nanoparticles containing one or more of metal zinc, bismuth, iron, copper or silver, specifically: bismuth-containing antibacterial nanoparticles (TB), zinc-containing antibacterial nanoparticles (TZ) or silver-containing antibacterial nanoparticles (TA).

[0008] Wherein, the mass ratio of fucoidan to antibacterial substance is 1:0.5-2.

[0009] Among them, the fucoidan is extracted from seaweed, has a molecular weight of 242.247, is electrically neutral or electronegative, and is used to achieve targeted aggregation at inflammatory sites and penetrate body barriers such as the gastric mucosal barrier.

[0010] Among them, the antibacterial drug is prepared as follows: in an alkaline or neutral reaction system, nitric acid or acetate containing zinc, bismuth, iron, copper, and silver is selected as a metal donor, and tea polyphenols is used as a metal chelator, and the metal is chelated by chemical reduction or hydrothermal precipitation.

[0011] The preparation method of the fucoidan modified complex is to synthesize the complex in a one-step method, take fucoidan and antibacterial substances respectively, stir them in water or ethanol solution, and wash them to obtain the fucoidan modified complex. It does not require complex synthesis conditions such as high temperature, high pressure, pH adjustment, and large instruments, and the operation is safe and simple. The polysaccharide complex was prepared by selecting a variety of antibacterial substances to verify the versatility of the preparation method.

[0012] Wherein, the reaction temperature is room temperature and the reaction time is 0.5 to 1 h.

[0013] The final product was collected by centrifugation (25°C, 8000 rpm, 10 min) or freeze-dried.

[0014] The above-mentioned fucoidan modified complex with bacteria targeting can be used in the preparation of drugs for treating bacterial infections.

[0015] The bacteria include Helicobacter pylori, Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Streptococcus pneumoniae, Pseudomonas aeruginosa or Enterococcus faecium.

[0016] The infectious strain is selected from at least one of Helicobacter pylori ATCC 26695 strain, Helicobacter pylori NSH 57 strain, and Helicobacter pylori SS1 strain.

[0017] Among them, the fucoidan complex combines with bacterial surface proteins to achieve dual targeting of the drug to bacteria and inflammatory sites, prolong the retention time, enhance the drug's specific bactericidal effect, reduce the colonization of pathogenic bacteria, reduce the nonspecific killing of beneficial bacteria, remove irritating substances, and relieve inflammation at the infected site.

[0018] Principle of the invention: The improved fucoidan complex with bacterial targeting of the present invention uses metal ions as the main bactericidal substance, and achieves an effective bactericidal effect by destroying the integrity of bacterial membranes, inhibiting bacterial protein activity, and reducing bacterial metabolism. However, the single use of such metal antibacterial substances faces the problems of poor targeting and short retention time, and will damage the normal flora and affect the normal function of the body. Therefore, fucoidan with insufficient antibacterial activity but good auxiliary effect is selected for improvement, and the two synergistically kill bacteria. The improved complex modified with fucoidan, on the one hand, can achieve targeted binding of drugs to bacteria by binding to bacterial surface proteins, such as adhesin Bab A, thereby improving the efficacy of the drug and avoiding the impact on beneficial bacteria. On the other hand, by changing the charge and hydrophilicity of the drug, the drug can be effectively delivered to the site of infection, prolonging the retention time of the affected area and improving the therapeutic effect in vivo.

[0019] The experimental results show that the fucoidan complex co-incubated with different types of bacteria all showed a certain antibacterial effect, among which the killing effect on Helicobacter pylori in a simulated gastric acid environment was the most prominent. Subsequently, its application in the treatment of Helicobacter pylori bacterial infection was verified, and it showed excellent antibacterial properties both in vivo and in vitro, including the following three therapeutic effects: (1) Prolonging the retention of the affected area. By using fucoidan for drug improvement, the retention of the drug was significantly prolonged; (2) Targeting pathogenic bacteria. After co-incubation with bacteria, the polysaccharide complex adheres to the bacterial surface, enhancing drug-specific bactericidal, significantly reducing pathogenic bacteria colonization, and reducing nonspecific killing of beneficial bacteria; (3) Targeting the inflammatory site, gathering to the inflammatory site through the principle of electrostatic adsorption, removing irritating substances, and effectively alleviating inflammation at the infected site. Therefore, the fucoidan modified complex of the present invention not only achieves functional complementarity, but also achieves synergistic synergy of effect, breaking the limitations of antibacterial drugs in practical applications, and achieving further improvement of the effect.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The fucoidan modified complex with bacterial targeting of the present invention, through the combination of fucoidan and antibacterial substances, will achieve dual targeting of bacteria and inflammatory sites, prolong the retention time, effectively relieve inflammation at the infection site and achieve the effect of specific bactericidal; in vitro experimental results show that after fucoidan modification, the bactericidal effect of the drug is increased by at least 2 times, and the retention in the stomach is extended from 1 hour to more than 2 hours. Animal experimental results show that compared with the existing clinical quadruple drugs, the fucoidan modified complex of the present invention has improved the bactericidal effect on drug-resistant strains by nearly an order of magnitude, and the inflammation level and gastric mucosal damage have been significantly restored. In addition, it also avoids the drawbacks of the complicated medication of quadruple therapy; (2) The present invention adopts a one-step preparation method, which does not require complex synthesis conditions such as high temperature, high pressure, pH adjustment, and does not require large-scale instruments. The operation is safe and simple, and it is suitable for large-scale production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The particle size (a) and potential (b) of the bismuth-containing fucoidan complex TBF of Example 1;

[0022] Figure 2 This is a scanning electron microscope image of the bismuth-containing fucoidan complex TBF of Example 1 after co-incubation with Helicobacter pylori;

[0023] Figure 3 The antibacterial effect of bismuth-containing fucoidan complex on Helicobacter pylori, wherein (a) is a statistical graph of bacterial survival rate with different concentrations of TBF, and (b) is a statistical graph of bacterial survival rate with antibacterial substances before and after improvement;

[0024] Figure 4 The bactericidal effect of fucoidan on Helicobacter pylori;

[0025] Figure 5 The antibacterial effect of bismuth-containing fucoidan complex TBF on different bacteria, including the plate colony count pictures of TBF against (a) Escherichia coli, (b) Staphylococcus aureus, (c) Acinetobacter baumannii, (d) Streptococcus pneumoniae, (e) Pseudomonas aeruginosa, and (f) Enterococcus faecium;

[0026] Figure 6 The effect of bismuth-containing fucoidan complex TBF on the activity of probiotics, wherein (a) is the statistical graph of the survival rate of TBF on Lactobacillus gasseri, Lactobacillus crispatus, Lactobacillus paracasei, Escherichia coli 1917, and Helicobacter pylori, and (b) is the statistical graph of the survival rate of Lactobacillus paracasei by antibacterial substances before and after improvement;

[0027] Figure 7 This is a statistical chart of Helicobacter pylori colonization in the stomach of mice after treatment with different treatment methods;

[0028] Figure 8 The expression levels of inflammation-related proteins in the stomach of mice after treatment with different treatment methods;

[0029] Fig. 9 These are the results of HE staining of the main organs of mice. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention is further described below in conjunction with the examples. The test materials used in the examples can all be purchased through conventional channels.

[0031] Example 1

[0032] The improved fucoidan complex with bacteria targeting of the present invention, wherein the bismuth-containing fucoidan complex (TBF) is obtained by compounding fucoidan (FU) and bismuth-containing antibacterial nanoparticles (TB).

[0033] The preparation method of bismuth-containing antibacterial nanoparticles (TB) is as follows: 146.2 mg Bi(NO3)3·5H2O is added to a glycine solution preheated to 75°C, and the pH is adjusted to 9 with a 3M NaOH aqueous solution. 75 μL 8.1M dithiopropanol, 3 mL 3mM polyvinylpyrrolidone (PVP-K10), and 7 mL 1M NaBH4 are added in sequence. After stirring for 10 minutes, the residual reagents are removed by dialysis, and the product (Bi NPs) is collected by freeze drying. 5 mg Bi NPs are dissolved in 2 mL of water, and 1 mL of tea polyphenol aqueous solution (2.5 mg / mL) is slowly dripped in. Stir at room temperature for 2 hours, and the residual reagents are removed by dialysis. The resulting product is TB.

[0034] The preparation method of bismuth-containing fucoidan complex (TBF) is as follows: the polysaccharide complex is prepared at a mass ratio of 1.5:1, 7.5 mg TB and 5 mg FU are taken respectively, stirred and reacted in an aqueous solution for 0.5 h, and the residual reagents are removed by dialysis. The obtained product is the bismuth-containing fucoidan complex, which is recorded as TBF.

[0035] The bismuth-containing fucoidan complex TBF prepared in Example 1 was taken and its particle size and potential were detected. Figure 1 As shown in a, the hydration kinetic diameter of TBF is 135nm, and PDI = 0.266, which proves that it has good dispersibility in water. Since some mucosal barriers in the body, such as the gastric mucosa, are negatively charged, it is easier for the drug to pass through and reach the infection site when it is electrically neutral or electronegative. Figure 1 As shown in b, after modification of fucoidan, the electronegativity of TBF is enhanced, which theoretically helps TBF to further exert its therapeutic effect in vivo.

[0036] Example 2

[0037] The improved fucoidan complex with bacteria targeting of the present invention, wherein the zinc-containing fucoidan complex (TZF) is obtained by compounding fucoidan (FU) and zinc-containing antibacterial nanoparticles (TZ).

[0038] The preparation method of zinc antibacterial nanoparticles (TZ) is as follows: 0.5mmol Zn(CH3COO)2·2H2O is dispersed in 10mL methanol solution and preheated to 85℃. 8mL NaOH aqueous solution is slowly dripped in a molar ratio of 1:2, and reacted at 85℃ for 6h. The residual reagent is removed by washing with pure water, and the precipitate (ZnO NPs) is collected by centrifugation at 8000rpm. 10mg ZnO NPs are resuspended in 4mL ethanol solution, and 3mL tea polyphenols (TP) and 3mL Bi(NO3)3·5H2O ethanol solution are added in sequence at a mass ratio of 1:1:3, and the reaction is continued at room temperature for 0.5h. The residual reagent is removed by washing with pure water, and the precipitate is collected by centrifugation at 8000rpm. The obtained product is TZ.

[0039] The preparation method of zinc-containing fucoidan complex (TZF) is as follows: the polysaccharide complex is prepared at a mass ratio of 1:1. 45 mg of fucoidan (FU) and TZ powder are taken respectively, resuspended in 10 mL of ethanol solution and mixed into a 20 mL reaction system, and stirred at room temperature for 0.5 h. The residual reagent is washed with pure water, and the precipitate is collected by centrifugation at 8000 rpm. The obtained product is the zinc-containing fucoidan complex, which is recorded as TZF.

[0040] Example 3

[0041] The improved fucoidan complex with bacteria targeting of the present invention, wherein the silver-containing fucoidan complex (TAF) is obtained by compounding fucoidan (FU) and silver-containing antibacterial nanoparticles (TA).

[0042] The method for preparing silver-containing antibacterial nanoparticles (TA) is as follows: 5 mg of AgNO3 is dissolved in 2.5 mL of ethanol, and then 1 mL of tea polyphenols (TP) of the same mass is slowly dripped in, and the mixture is vortexed for 30 minutes at room temperature. The residual reagent is dialyzed away, and the resulting product is TA.

[0043] The preparation method of silver-containing fucoidan complex (TAF) is as follows: the polysaccharide complex is prepared at a mass ratio of 1.5:1. 7.5 mg TA and 5 mg FU are respectively taken, stirred and reacted in an aqueous solution for 0.5 h, and the residual reagents are removed by dialysis. The obtained product is the silver-containing fucoidan complex, which is recorded as TAF.

[0044] Example 4

[0045] Verification of the targeting binding ability of the improved fucoidan complex with bacteria targeting of the present invention to Helicobacter pylori:

[0046] Bacterial culture: Helicobacter pylori NSH 57 strain was taken out from the -80°C refrigerator, thawed naturally, 100 μL was inoculated into solid culture medium, and cultured in a three-gas incubator (37°C, 5% O2, 10% CO2, 85% N2) for 72 h.

[0047] Electron microscopy observation: Take the strain out of the incubator, scrape the bacteria and suspend them in fresh sterile Brucella broth to make a suspension, and dilute the suspension to a concentration of 5×10 8 CFU / mL.

[0048] Use sterile PBS to dilute the bismuth-containing fucoidan complex TBF to 200μg / mL, then take 1mL of sterile PBS (control group) and 1mL of TBF (experimental group) and mix them with 1mL of bacterial solution, and place them in a three-gas incubator for co-culture for 12h. Take out the bacterial solution, centrifuge it at 8000rpm for 5min at 4℃ to remove the residual substances, wash it with PBS 1-2 times and repeat the centrifugation to collect the bacteria; then use a scanning electron microscope to observe the binding of bacteria and TBF.

[0049] like Figure 2 As shown, it is a scanning electron micrograph after TBF and Helicobacter pylori are co-incubated. The white arrow in the figure points to TBF. It can be clearly observed that TBF adheres to the bacteria, and obvious drug binding phenomenon is observed on the bacterial surface. This indicates that the improved fucoidan complex of the present invention can achieve targeted binding of drugs to bacteria by binding to bacterial surface proteins, thereby improving the efficacy of the drug.

[0050] Example 5

[0051] Verification of the inhibitory effect of the bacteria-targeting fucoidan modified complex of the present invention on the activity of Helicobacter pylori:

[0052] MIC determination: Take the strain out of the incubator, scrape the bacteria and suspend them in fresh sterile Brucella broth to make a suspension, and dilute the suspension to a concentration of 1×10 7 CFU / mL.

[0053] Use sterile PBS to dilute the bismuth-containing fucoidan complex TBF into solutions of 200μg / mL, 100μg / mL, 50μg / mL, 25μg / mL, 12.5μg / mL, 6.25μg / mL, and 3.125μg / mL. Take 100μL of bacterial solution and 100μL of TBF of different concentrations and add them to 96-well plates respectively, and set up a blank control group (no strain inoculation, simple sterile culture medium) and a positive control group (only inoculated strain, simple sterile PBS). Repeat each group at least 3 times, and then place it in a three-gas incubator for co-culture. Take out the 96-well plate and observe with the naked eye. The concentration corresponding to the obviously clear liquid in the well is the MIC, and the OD is measured. 600, calculate the bacterial survival rate.

[0054] MBC assay: 100 μL of liquid was taken from the above 96-well plate, evenly spread on the solid culture medium, placed in a three-gas incubator for co-cultivation, the bacteria on the plate were counted and the bacterial survival rate was calculated.

[0055] like Figure 3 As shown in a, the antibacterial activity of TBF gradually increases with the increase of concentration. When the TBF concentration is 25 μg / mL, the survival rate of bacteria drops to 2%, and the number of bacteria decreases by about 2 orders of magnitude, with a significant bactericidal effect. Figure 3 In b, at the same drug concentration, the effect of the antibacterial drug without fucoidan modification is not very ideal, while the bactericidal effect is improved by nearly 50% after modification. This is because fucoidan targets more drugs to adhere to bacteria, so that the bactericidal active ingredients are more concentrated on the bacterial surface or even enter the bacteria, thereby enhancing the efficacy of the drug.

[0056] like Figure 4 As shown in the figure, single FU has no obvious bactericidal effect on the clinically isolated multidrug-resistant Helicobacter pylori involved in this experiment. Therefore, by combining fucoidan with antibacterial drugs to form an improved complex, an effective combination of bactericidal effects is achieved, with significant synergistic enhancement.

[0057] Example 6

[0058] Verify the inhibitory effect of the bacteria-targeting fucoidan modified complex of the present invention on the activity of other bacteria:

[0059] Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Enterococcus faecium were revived respectively. The bacterial solution in the logarithmic growth phase was co-cultured with TBF (final concentration 200 μg / mL) to detect the antibacterial activity of TBF against different strains. For specific experimental methods, see Example 5.

[0060] like Figure 5 As shown in the figure, TBF has a certain bactericidal effect on the above six bacteria. When the TBF concentration is 200μg / mL, the number of the above bacteria decreased by about 1-2 orders of magnitude after co-incubation with TBF. Among them, the bactericidal effect on Pseudomonas aeruginosa and Enterococcus faecium is better than that on the other four bacteria, but still inferior to that on Helicobacter pylori. On the one hand, since Helicobacter pylori survives in an acidic environment, it is conducive to the release of bismuth ions, the main bactericidal substance; on the other hand, bismuth ions have affinity for the active protein of Helicobacter pylori, which can better inhibit the activity of the protein and thus achieve a bactericidal effect.

[0061] Example 7

[0062] Verification of the protective effect of the bacteria-targeting fucoidan modified complex of the present invention on beneficial bacteria:

[0063] Probiotics Lactobacillus gasseri, Lactobacillus crispatus, Lactobacillus paracasei, Lactobacillus rhamnosus, Escherichia coli 1917, and pathogenic bacteria Helicobacter pylori were cultured according to standard methods. Bacteria in the logarithmic growth phase were taken and diluted to a concentration of 1×10 7 CFU / mL. The bacteria were co-cultured with the antibacterial drug Bi NPs, bismuth-containing fucoidan modified complex TBF, and fucoidan, and the OD600 was measured and the bacterial survival rate was calculated.

[0064] like Figure 6 As shown in the results, at the same concentration, TBF has a significantly better bactericidal effect on the pathogenic bacteria Helicobacter pylori than the other five probiotics, indicating that TBF can avoid nonspecific killing of beneficial bacteria. Subsequently, the effects of antimicrobial drugs and fucoidan on the activity of probiotics were further explored. Taking Lactobacillus paracasei as an example, the experimental results showed that antimicrobial drugs at high concentrations would reduce the activity of probiotics, while the fucoidan-modified complex would not affect the activity of probiotics, proving that fucoidan plays a key role in protecting probiotics.

[0065] Example 8

[0066] Verification of the therapeutic effect of the bacterial-targeting fucoidan modified complex of the present invention on the gastritis mouse model:

[0067] Animal modeling: 6-8 week old C57BL / 6 mice weighing 17-20 g were selected. All animal experiments were conducted in accordance with the Guidelines for the Care and Use of Laboratory Animals of China Pharmaceutical University and approved by the Animal Ethics Committee of the School of Pharmacy of China Pharmaceutical University. The mice were randomly divided into a healthy control group and an infection model group. The healthy control group was gavaged with 0.3 mL of sterile PBS, and the model group was gavaged with an equal volume of 2×10 9 CFU / mL Helicobacter pylori suspension was administered once a day for 3 consecutive days, and the animals were deprived of food and water for 3 hours before and after intragastric administration. The animals were kept for 1 week after the last intragastric administration, and the stomachs were taken out to determine the Helicobacter pylori infection and whether the model was successfully established by plate counting, urease detection, polymerase chain reaction, and HE staining.

[0068] 2. Effect evaluation: The mice were randomly divided into 4 groups (healthy control group, infection model group, TBF treatment group, quadruple therapy group), 8 mice in each group, and the model was established according to the above method. After the model was established, treatment was carried out. The healthy control group and the infection model group were gavaged with 0.3 mL of sterile PBS, the TBF treatment group was gavaged with 0.3 mL of 10 mg / mL TBF, and the quadruple therapy group was gavaged with 0.3 mL of quadruple drugs (amoxicillin, levofloxacin, esomeprazole, potassium citrate bismuth) once a day for 5 consecutive days. Before and after treatment, the mice were fasted and deprived of water for 3 hours, and the body weight changes were recorded every day. (1) Bacterial colonization detection. 24 hours after the end of treatment, the stomach was taken and placed in sterile saline. After homogenization, it was further diluted 10 times with sterile saline. 100 μL of the homogenate with different dilution multiples was taken for plating and placed in a three-gas incubator for culture. The number of colonies was then counted and converted to the bacterial load in each stomach. (2) Inflammation clearance detection. At the mRNA level, the Trizol method was used to extract RNA from the gastric tissue of each group of mice, and the expression levels of inflammatory factors (IL-6, IL-17, INF-γ) were detected by quantitative polymerase chain reaction (qPCR). At the protein level, the gastric tissue proteins of each group of mice were first extracted, and the expression level of the inflammatory factor IL-6 was detected by protein immunoblotting. (3) Evaluation of mucosal recovery. The gastric tissues of each group of mice were embedded and sectioned, and the recovery of damaged gastric mucosa was evaluated by HE staining and immunofluorescence staining (ZO-1 / E-Cadherin / DAPI). (4) Safety evaluation. The main organs of each group of mice were embedded and sectioned, and the in vivo safety of TBF was evaluated by HE staining.

[0069] like Figure 7 As shown in the results, TBF significantly reduced the colonization of Helicobacter pylori in the stomach of mice, and the effect was better than that of the quadruple drug group. Further experiments confirmed that TBF can reduce the production of inflammatory factors in the stomach by removing irritating substances such as reactive oxygen species (ROS), which helps to recover from gastric inflammation. Figure 8 The results shown here verify this at the protein level. In addition, in vivo safety issues should be considered when designing drugs. Fig. 9 As shown, after mice were treated with TBF, no obvious lesions occurred in major organs such as the heart, liver, spleen, lungs, and kidneys, which to a certain extent confirmed the in vivo safety of TBF.

[0070] Therefore, the improved fucoidan complex with bacteria targeting of the present invention realizes dual targeting of drugs to bacteria and inflammatory sites, prolongs the retention time, enhances drug-specific bactericidal effect, reduces colonization of pathogenic bacteria, reduces nonspecific killing of beneficial bacteria, protects beneficial bacteria, removes irritating substances, relieves inflammation at the infection site, and has good safety in vivo, and is suitable for promotion and use.

Claims

1. A modified fucoidan complex with bacterial targeting, characterized in that: The complex is a composite of fucoidan and antibacterial substances, and is obtained by modifying antibacterial drugs by means of physical coating and chemical connection, with fucoidan as the targeting substance.

2. The improved fucoidan complex according to claim 1, characterized in that: The antibacterial substance is antibacterial nanoparticles containing one or more of metal zinc, bismuth, iron, copper or silver.

3. The improved fucoidan complex according to claim 1, characterized in that: The mass ratio of the fucoidan to the antibacterial substance is 1:0.5-2.

4. The improved fucoidan complex according to claim 1, characterized in that: The fucoidan is obtained from seaweed and is electrically neutral or electronegative.

5. The improved fucoidan complex according to claim 2, characterized in that: The antibacterial drug is prepared by selecting nitric acid or acetate containing zinc, bismuth, iron, copper or silver as a metal donor in an alkaline or neutral reaction system, using tea polyphenols as a metal chelating agent, and chelating the metal through chemical reduction or hydrothermal precipitation.

6. A method for preparing the improved fucoidan complex according to claim 1, characterized in that: The preparation method is to synthesize the composite by a one-step method, taking fucoidan and antibacterial substances respectively, stirring them in water or ethanol solution, and washing them to obtain the fucoidan modified composite.

7. The preparation method according to claim 6, characterized in that: The reaction temperature is room temperature and the reaction time is 0.5 to 1 h.

8. Use of the improved fucoidan complex with bacteria targeting property as claimed in claim 1 in the preparation of drugs for treating bacterial infections.

9. The use according to claim 8, characterized in that: The bacteria include Helicobacter pylori, Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, Streptococcus pneumoniae, Pseudomonas aeruginosa or Enterococcus faecium.

10. The use according to claim 8, characterized in that: The fucoidan complex combines with bacterial surface proteins to achieve dual targeting of the drug to bacteria and inflammatory sites, prolong the retention time, enhance the drug's specific bactericidal effect, reduce the colonization of pathogenic bacteria, reduce the nonspecific killing of beneficial bacteria, remove irritating substances, and relieve inflammation at the infected site.

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