Zinc vanillate as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic synthesis, in particular to zinc vanillate and a preparation method and application thereof. The zinc vanillate provided by the invention has a structure as shown in a formula I. Therefore, the zinc vanillate provided by the invention is good in thermal stability at 200 DEG C, and data of the embodiment shows that the zinc vanillate provided by the invention has antioxidant activity and broad-spectrum antibacterial activity. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to zinc vanillate and a preparation method and application thereof. Background Art

[0002] Vanillic acid (VA) is a plant secondary metabolite that exhibits good biocompatibility and has antibacterial, antioxidant, anti-inflammatory, antiplatelet aggregation and liver protection effects. It is a natural phenolic acid with great research value and application potential. The antibacterial activity of vanillic acid is negatively correlated with pH, ​​and the bactericidal rate decreases with the increase of pH value, indicating that VA has limited antibacterial ability in weakly alkaline environments such as the intestine. At the same time, vanillic acid has defects such as being unstable in the presence of light and easily oxidized; it is easy to sublimate at high temperatures and difficult to process, which limits its application.

[0003] The influence of metal ions on the antioxidant and antibacterial properties of phenolic compound complexes has become a topic of concern. Currently, phenolic acid metal complexes such as zinc salicylate and zinc acetylsalicylate (zinc aspirin) have been widely used. However, there is currently no antioxidant or antibacterial agent prepared using vanillic acid as a metal complex. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a zinc vanillate and a preparation method and application thereof. The zinc vanillate provided by the present invention has antioxidant activity and broad-spectrum antibacterial activity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a zinc vanillate having a structure shown in Formula I:

[0007]

[0008] The present invention also provides a method for preparing zinc vanillate described in the above technical solution, comprising the following steps:

[0009] When preparing zinc vanillate, the raw material zinc source is divided into a first zinc source or a second zinc source; the first zinc source is one or more of zinc oxide, zinc hydroxide and basic zinc carbonate; the second zinc source is one or more of zinc chloride, zinc nitrate and zinc sulfate;

[0010] When the zinc source is the first zinc source, the preparation method comprises the following steps:

[0011] dissolving vanillic acid in an ethanol aqueous solution to obtain a first vanillic acid solution;

[0012] mixing the first zinc source and the vanillic acid solution to perform a first coordination reaction to obtain zinc vanillate;

[0013] When the zinc source is the second zinc source, the preparation method comprises the following steps:

[0014] After dissolving vanillic acid in an ethanol aqueous solution, the pH value is adjusted to 6.0 to 8.5 to obtain a second vanillic acid solution;

[0015] The second zinc source and the second vanillic acid solution are mixed to carry out a second coordination reaction to obtain zinc vanillate.

[0016] Preferably, the molar ratio of the vanillic acid to the first zinc source or the second zinc source is (1-3):1.

[0017] Preferably, the volume concentration of the ethanol aqueous solution is 15-40%.

[0018] Preferably, the temperature of the first coordination reaction and the second coordination reaction are independently 20 to 80° C., and the insulation time is independently 30 to 180 min.

[0019] Preferably, after the first coordination reaction or the second coordination reaction, the method further comprises filtering the system obtained from the first coordination reaction or the second coordination reaction, and washing the obtained solid phase with water and then drying it.

[0020] Preferably, the drying temperature is 50-100° C., and the drying time is 4-24 hours.

[0021] Preferably, the reagent for adjusting the pH value is sodium hydroxide solution.

[0022] The present invention also provides the use of the zinc vanillate described above or the zinc vanillate prepared by the above preparation method in inhibiting bacteria and resisting oxidation.

[0023] Preferably, the bacteria include one or more of Escherichia coli, Staphylococcus aureus, Vibrio alginolyticus, aquatic animal pathogen isolates Aeromonas veronii, Citrobacter freundii, Streptococcus agalactiae, Staphylococcus worteri and Vibrio parahaemolyticus.

[0024] The present invention provides a zinc vanillate having a structure shown in Formula I:

[0025] The Zn-O coordination bond makes it thermally stable. When Zn forms a coordination bond with an atom with strong electronegativity (such as an oxygen atom), Zn 2+ The electron cloud of Zn 2+ It exhibits a weaker electron donor property, reducing the possibility of vanillic acid ligand oxidation reaction in zinc vanillate during heating, thereby improving the thermal stability of zinc vanillate. Therefore, the zinc vanillate provided by the present invention has good thermal stability at 200°C, and the data of the examples show that the zinc vanillate provided by the present invention has antioxidant activity and broad-spectrum antibacterial activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The morphology and microstructure of VA-Zn obtained in Example 1;

[0027] Figure 2 It is the infrared absorption curve of VA and VA-Zn prepared in Example 1;

[0028] Figure 3 The PXRD pattern of VA-Zn obtained in Example 1;

[0029] Figure 4 This is the thermogravimetric analysis diagram of VA-Zn obtained in Example 1;

[0030] Figure 5 The scavenging effect of VA-Zn prepared in Example 1 on DPPH at different concentrations;

[0031] Figure 6 The inhibition zones after bacteria were treated with VA and VA-Zn prepared in Example 1;

[0032] Figure 7 This is the SEM image of the bacteria treated with VA-Zn obtained in Example 1 for 2 hours;

[0033] Figure 8 This is an optical microscopic image of the biofilm of bacteria exposed to VA-Zn of Example 1 for 24 hours. DETAILED DESCRIPTION

[0034] The present invention provides a zinc vanillate having a structure shown in Formula I:

[0035]

[0036] The present invention also provides a method for preparing zinc vanillate described in the above technical solution, comprising the following steps:

[0037] When preparing zinc vanillate, the raw material zinc source is divided into a first zinc source or a second zinc source; the first zinc source is one or more of zinc oxide, zinc hydroxide and basic zinc carbonate; the second zinc source is one or more of zinc chloride, zinc nitrate and zinc sulfate;

[0038] When the zinc source is the first zinc source, the preparation method comprises the following steps:

[0039] dissolving vanillic acid in an ethanol aqueous solution to obtain a first vanillic acid solution;

[0040] mixing the first zinc source and the vanillic acid solution to perform a first coordination reaction to obtain zinc vanillate;

[0041] When the zinc source is the second zinc source, the preparation method comprises the following steps:

[0042] After dissolving vanillic acid in an ethanol aqueous solution, the pH value is adjusted to 6.0 to 8.5 to obtain a second vanillic acid solution;

[0043] The second zinc source and the second vanillic acid solution are mixed to carry out a second coordination reaction to obtain zinc vanillate.

[0044] As an implementation manner, the volume concentration of the ethanol aqueous solution is 15-40%, and in a specific embodiment, it can be 20%.

[0045] As one embodiment, the molar ratio of the vanillic acid to the first zinc source or the second zinc source is (1-3):1. As another embodiment, the molar ratio of the vanillic acid to the first zinc source or the second zinc source is (1-2.5):1. In a specific embodiment, the molar ratio of the vanillic acid to the first zinc source or the second zinc source can be (1.2-2):1.

[0046] As an embodiment, the temperature of the first coordination reaction and the second coordination reaction is independently 20 to 80° C., as another embodiment, the temperature of the first coordination reaction and the second coordination reaction is independently 25 to 65° C., in a specific embodiment, the temperature of the first coordination reaction and the second coordination reaction is independently 30 to 50° C. As an embodiment, the insulation time of the first coordination reaction and the second coordination reaction is independently 30 to 180 min, as another embodiment, the insulation time of the first coordination reaction and the second coordination reaction is independently 60 to 160 min, in a specific embodiment, the insulation time of the first coordination reaction and the second coordination reaction can be independently 80 to 120 min.

[0047] As an embodiment, when the zinc source is the second zinc source, after dissolving vanillic acid in an ethanol aqueous solution, the pH value can be adjusted to 6.0 to 8.5. In a specific embodiment, the pH value can be adjusted to 6.5 to 7.5.

[0048] As an embodiment, the reagent for adjusting the pH value is a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution can be 20%.

[0049] As an embodiment, after the first coordination reaction or the second coordination reaction, the system obtained by the first coordination reaction or the second coordination reaction is filtered, and the obtained solid phase is washed with water and then dried.

[0050] As one embodiment, the drying temperature is 50-100°C, as another embodiment, the drying temperature is 55-90°C, and in a specific embodiment, the drying temperature can be 60-80°C; as one embodiment, the drying time is 4-24h, as another embodiment, the drying time is 6-20h, and in a specific embodiment, the drying time can be 8-12h.

[0051] The preparation method provided by the invention has mild reaction conditions, simple operation and is suitable for large-scale production.

[0052] The present invention also provides the zinc vanillate or the use of zinc vanillate in inhibiting bacteria and anti-oxidation as described in the above technical solution.

[0053] As an embodiment, the bacteria include one or more of Escherichia coli, Staphylococcus aureus, Vibrio alginolyticus, aquatic animal pathogen isolates Aeromonas veronii, Citrobacter freundii, Streptococcus agalactiae, Staphylococcus worderi and Vibrio parahaemolyticus.

[0054] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0055] Examples 1 to 8

[0056] The preparation methods of Examples 1 to 8 are as follows:

[0057] Dissolve vanillic acid in 15 mL of 20% ethanol aqueous solution to obtain a vanillic acid solution;

[0058] The first zinc source and the vanillic acid solution are mixed to carry out the first coordination reaction. After the reaction is completed, the reaction is filtered, and the solid phase obtained by filtration is repeatedly washed with water for 3 times, and then air-dried (at a temperature of 60° C.) to obtain the product vanillic acid zinc (VA-Zn). The type of the first zinc source, the molar ratio of the first zinc source and vanillic acid, and the temperature and time of the first coordination reaction are all shown in Table 1.

[0059] The present invention also determines the zinc content in the zinc vanillate prepared in Examples 1 to 8, and the determination method is EDTA complexometric titration, that is, accurately weigh 0.0500g to 0.1000g of the sample in a conical flask, add 20mL of deionized water, add 10.0mL of ammonia water-ammonium chloride buffer solution with a pH of ≈10, add 2 drops of 0.5% chrome black T indicator, shake well, and then titrate with 0.0100mol / EDTA standard solution; the color of the solution changes from purple-red to royal blue at the titration endpoint.

[0060] The metal content (ρ) is expressed as mass percentage (%) and is calculated according to formula A:

[0061]

[0062] In formula A: C---concentration of EDTA standard solution (mol / L); V---volume of EDTA standard solution when titrating the sample (L); m---mass of sample (g); M---mass in grams per mole of metal (g / mol), Zn is 65.38.

[0063] Table 1 Statistics of the type of the first zinc source, the molar ratio of the first zinc source to vanillic acid, the temperature and time of the first coordination reaction in Examples 1 to 8

[0064] Example Zinc source <![CDATA[n(VA:Zn 2+ )]]> Reaction temperature / ℃ Reaction time / h Example 1 ZnO 1.2:1 25 2 Example 2 ZnO 1.2:1 30 2 Example 3 ZnO 1.2:1 60 2 Example 4 ZnO 1.5:1 25 3 Example 5 ZnO 2.2:1 25 3 Example 6 <![CDATA[Zn(OH) 2 ]]> 1:1 40 2.5 Example 7 <![CDATA[Zn(OH) 2 ]]> 1:1 40 2.5 Example 8 Basic zinc carbonate 1.05:1 40 2

[0065] Table 2 Statistics of the yield and zinc content of zinc vanillate obtained in Examples 1 to 8

[0066]

[0067]

[0068] Figure 1 The morphology and microstructure of VA-Zn prepared in Example 1 are shown in FIG. Figure 1 (a) is a macroscopic image of zinc vanillate; (b) is a crystal-optical microscope image of zinc vanillate; (c) is an energy spectrum image of zinc vanillate; (d) is a crystal-electron microscope image of zinc vanillate; (e) is an energy spectrum mapping image of the C element of zinc vanillate; (f) is an energy spectrum mapping image of the O element of zinc vanillate; (g) is an energy spectrum mapping image of the Zn element of zinc vanillate, from Figure 1 It can be seen that VA-Zn is a light yellow powder, and VA-Zn solid is a transparent rectangular microcrystal under an optical microscope. The surface of VA-Zn solid is smooth, and the grain size is 20μm. The energy dispersion X-ray image confirms the presence of C (0.27keV), O (0.53keV), Zn (1.02keV, 8.64keV and 9.06keV) elements. In addition, the energy spectrum scanning image shows that the C, O, and Zn elements of VA-Zn crystals are evenly and densely distributed, further proving that the prepared VA-Zn microcrystals are of high purity.

[0069] Figure 2 is the infrared absorption curve of VA and VA-Zn prepared in Example 1, wherein Figure 2 (a) is the FT-IR spectrum of (a); (b) is the FT-IR spectrum of (a) at 1800-1000cm -1 A partial enlarged view of Figure 2 It can be seen that VA is located at 3483cm -1 The peak at 1679 cm is the stretching vibration absorption peak of phenolic hydroxyl group. -1The C=O stretching vibration absorption peak conjugated with the benzene ring is at 3500-2500cm -1 A very broad absorption band of the characteristic peak of the carboxylic acid group is formed. VA-Zn is at 2500~3200cm -1 The characteristic absorption bands of carboxylic acid and C=O disappeared. The FTIR spectrum of VA-Zn showed that the absorption bands at 1670, 1558 and 1424, 1388 cm -1 Corresponding to the anti-stretching vibration of the carboxyl group ν as (COO - ) and stretching vibration ν s (COO - The -OH absorption peak of VA-Zn red-shifts to 3333 cm -1 , and at 3500~3200cm -1 The formation of a very broad absorption band may be caused by the strong hydrogen bonding of crystal water or the coordination of Zn with phenolic hydroxyl groups.

[0070] Figure 3 The PXRD pattern of VA-Zn prepared in Example 1 is shown in FIG. Figure 3 It can be seen that VA has strong characteristic diffraction peaks at 2θ values ​​of 9.42°, 12.94° and 16.64°. The diffraction peaks of VA disappear after coordination with metal. VA-Zn has new diffraction peaks at 2θ values ​​of 7.91°, 11.73° and 14.69°.

[0071] Figure 4 Thermogravimetric analysis of VA-Zn obtained in Example 1, wherein Figure 4 The middle is the thermal decomposition diagram of VA-Zn in air atmosphere; Figure 4 It can be seen that: VA-Zn has two steps in the first stage of weight loss at 40-200℃. The first DTG peak appears at 144℃, with a weight loss of 5.22%, and the second DTG peak appears at 180℃, with a weight loss of 7.45%. The total loss is 12.67%, which is the loss of water molecules; at 200-450℃, the main part of the ligand is decomposed, and the DTG peaks are at 346.4℃ and 393.6℃ respectively, with a total weight loss of 57.93%; the white component remaining after thermal decomposition of VA-Zn is ZnO, with a residual amount of 30.4%, and the converted zinc content is 24.42%.

[0072] Examples 9 to 13

[0073] The preparation methods of Examples 9 to 13 are as follows:

[0074] Dissolve vanillic acid in 15 mL of 20% ethanol aqueous solution, and then adjust the pH value with 20 wt.% NaOH solution to obtain a vanillic acid solution;

[0075] The second zinc source and the vanillic acid solution were mixed to carry out the second coordination reaction. After the reaction was completed, the solid phase was filtered, washed with water for three times, and dried with forced air (temperature was 55° C.) to obtain the product zinc vanillate. The type of the second zinc source, the molar ratio of the second zinc source and vanillic acid, and the temperature and time of the second coordination reaction were all shown in Table 3.

[0076] The present invention also measures the zinc content in the zinc vanillate prepared in Examples 9 to 13, using the same method as in Examples 1 to 8. The test results are shown in Table 4.

[0077] Table 3 Statistics of the type of the second zinc source, the molar ratio of the second zinc source to vanillic acid, pH, temperature and time of the second coordination reaction in Examples 9 to 13

[0078]

[0079] Table 4 Statistics of the yield and zinc content of zinc vanillate obtained in Examples 9 to 13

[0080] Example Yield / % Zinc content / % Example 9 93.78 24.38 Example 10 92.95 24.38 Embodiment 11 92.03 24.12 Example 12 91.04 24.43 Example 13 85.64 24.32

[0081] test:

[0082] (1) Antioxidant test

[0083] Accurately weigh 6 mg of 1,1-diphenyl-2-trinitrophenol (DPPH) powder and dissolve it in methanol and use a 100 mL volumetric flask to make up the volume, store in the dark, and obtain a 2 mmol / L DPPH solution. 50 mg of VA and VA-Zn prepared in Example 1 were respectively placed in a 100 mL volumetric flask, and deionized water was used as the solvent to make up the volume to prepare a 0.5 mg / mL sample solution. 50 μL, 100 μL, 200 μL, 300 μL, 400 μL, 800 μL, 1 mL, 1.5 mL and 2 mL were drawn from the sample solution with a pipette into a 15 mL centrifuge tube, and then filled to 5 mL with deionized water to make sample solutions of different mass concentrations, and then added to 5 mL of DPPH solution, respectively, and mixed evenly and reacted in a 37 ° C constant temperature shaker in the dark for 2 hours.

[0084] The spectrophotometer was zeroed with 50% methanol aqueous solution, and the absorbance A of the mixed solution of sample solution with different mass concentrations and DPPH was measured at 517nm. i ; Simultaneously measure the absorbance A of 5 mL of methanol mixed with 5 mL of sample solutions of different mass concentrations 0 And the absorbance A after mixing 5mL deionized water with 5mL DPPH solution j The free radical scavenging rate was calculated according to formula B.

[0085]

[0086] Figure 5 The scavenging effect of VA-Zn prepared in Example 1 on DPPH at different concentrations is shown in FIG. Figure 5 It can be seen that the scavenging rate of VA and VA-Zn on DPPH free radicals increases with the increase of concentration. At a drug concentration of 80 mg / L, the scavenging rate of VA-Zn reached 88.57%, while the maximum scavenging rate of VA at 80 mg / L was only 61.17%. The IC value of VA-Zn was obtained from the curve. 50 is 14.59 mg / L. Similarly, the IC of VA 50 The scavenging effect of VA-Zn on DPPH was better than that of vanillic acid.

[0087] (2) Antibacterial test

[0088] The antibacterial effects of VA and VA-Zn were evaluated using standard strains of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Vibrio alginolyticus (V. alginolyticus) and aquatic animal pathogen isolates of Aeromonas veronii (MS-A. veronii), Citrobacter freundii (MS-C. freundii), Streptococcus agalactiae (TM-S. agalactiae), Staphylococcus warneri (TM-S. warneri) and Vibrio parahaemolyticus (SV. parahaemolyticus) as experimental objects. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used as representatives of Gram-negative and Gram-positive bacteria, and the antibacterial mechanism of zinc vanillate was explored by observing the bacterial morphology after treatment with zinc vanillate using scanning electron microscopy and the degree of adhesion of bacterial biofilms using optical microscopy.

[0089] Figure 6 The inhibition zone (unit: mm) after VA and VA-Zn prepared in Example 1 were treated with bacteria. Figure 6 It can be seen that the inhibition zones of the eight bacteria treated with zinc vanillate are larger than those of vanillic acid. Except for the strains of Vibrio (SV.alginolyticus and SV.parahaemolyticus), the VA drug-sensitive tablets on the agar plates of other strains became smaller and the edges were transparent brown, indicating that the VA drug-sensitive tablets may be oxidized or decomposed by bacteria, and the antibacterial effect of VA is not long-lasting.

[0090] Figure 7 This is the SEM image of the bacteria treated with VA-Zn prepared in Example 1 for 2 hours, where Figure 7 (a) is a SEM image of VA-Zn prepared in Example 1 after treating Gram-negative bacteria for 2 hours. Figure 7 (b) is a SEM image of VA-Zn prepared in Example 1 after treating Gram-positive bacteria for 2 hours. Figure 7The middle arrow indicates a bacterial cavity or rupture, the blue box indicates a concave or deformed bacterial morphology, and the yellow box indicates that the bacterial binary fission is blocked and the bacterial morphology is abnormal. Figure 7 It can be seen that compared with the smooth and plump bacterial surface of the control group, the cell wall membrane of the bacteria treated with VA-Zn was distorted and severely damaged, and the bacterial morphology showed volume shrinkage, depression and cavity.

[0091] Figure 8 This is an optical microscopic image of the biofilm of the bacteria exposed to VA-Zn of Example 1 for 24 hours. Figure 8 It can be seen that under VA-Zn treatment, compared with the dense and thick biofilm in the control group, the bacterial biofilm adhesion after treatment showed dispersion and voids, and the bacterial biofilm adhesion area was significantly reduced, indicating that VA-Zn can inhibit the formation of bacterial biofilm.

[0092] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A zinc vanillate, characterized in that It has the structure shown in formula I:

2. The method for preparing zinc vanillate according to claim 1, comprising the following steps: When preparing zinc vanillate, the raw material zinc source is divided into a first zinc source or a second zinc source; the first zinc source is one or more of zinc oxide, zinc hydroxide and basic zinc carbonate; the second zinc source is one or more of zinc chloride, zinc nitrate and zinc sulfate; When the zinc source is the first zinc source, the preparation method comprises the following steps: dissolving vanillic acid in an ethanol aqueous solution to obtain a first vanillic acid solution; mixing the first zinc source and the vanillic acid solution to perform a first coordination reaction to obtain zinc vanillate; When the zinc source is the second zinc source, the preparation method comprises the following steps: After dissolving vanillic acid in an ethanol aqueous solution, the pH value is adjusted to 6.0 to 8.5 to obtain a second vanillic acid solution; The second zinc source and the second vanillic acid solution are mixed to carry out a second coordination reaction to obtain zinc vanillate.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the vanillic acid to the first zinc source or the second zinc source is (1-3):

1.

4. The preparation method according to claim 2, characterized in that: The volume concentration of the ethanol aqueous solution is 15-40%.

5. The preparation method according to claim 2, characterized in that: The temperature of the first coordination reaction and the second coordination reaction are independently 20 to 80° C., and the insulation time is independently 30 to 180 min.

6. The preparation method according to claim 2, characterized in that: After the first coordination reaction or the second coordination reaction, the method further comprises filtering the system obtained from the first coordination reaction or the second coordination reaction, and washing the obtained solid phase with water and then drying it.

7. The preparation method according to claim 6, characterized in that: The drying temperature is 50-100° C., and the drying time is 4-24 hours.

8. The preparation method according to claim 2, characterized in that: The reagent for adjusting pH value is sodium hydroxide solution.

9. Use of the zinc vanillate according to claim 1 or the zinc vanillate prepared by the preparation method of any one of claims 2 to 8 in inhibiting bacteria and anti-oxidation.

10. The use according to claim 9, wherein the bacteria include one or more of Escherichia coli, Staphylococcus aureus, Vibrio alginolyticus, aquatic animal pathogen isolates Aeromonas veronii, Citrobacter freundii, Streptococcus agalactiae, Staphylococcus worderi and Vibrio parahaemolyticus.

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