Lycium barbarum polysaccharide-zinc compound, preparation method thereof and application of lycium barbarum polysaccharide-zinc compound in zinc supplementing preparation

Abstract

The invention discloses a lycium barbarum polysaccharide-zinc compound, a preparation method thereof and application of the lycium barbarum polysaccharide-zinc compound in a zinc supplementing preparation. The invention belongs to the technical field of high-molecular polysaccharide chelation. The invention solves the problems of high preparation cost, low yield and low zinc content of the zinc supplement preparation in the prior art. The lycium barbarum polysaccharide is subjected to incomplete hydrolysis to obtain the low-molecular-weight lycium barbarum polysaccharide with the weight-average molecular weight of about 3680Da, the zinc ion chelation rate of the lycium barbarum polysaccharide-zinc compound prepared with the small molecular weight can reach 95-98%, the zinc content can reach 28-35%, and the zinc ion chelation rate and the zinc content are far higher than those in the prior art. The lycium barbarum polysaccharide-zinc compound prepared by the invention has the advantages of high bioavailability, low toxicity, easiness in digestion and absorption and the like, shows excellent biological activity in the aspects of oxidation resistance, blood sugar reduction, inflammation resistance, bacteria resistance, liver protection and the like, and can also be used as a high-quality zinc supplementing agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of macromolecular polysaccharide chelation, and specifically relates to a wolfberry polysaccharide-zinc complex, a preparation method thereof, and an application thereof in zinc supplement preparations. Background Art

[0002] Wolfberry polysaccharide is an important active ingredient in wolfberry, with various biological effects such as anti-tumor, antioxidant, anti-aging, and anti-inflammatory effects, and has good research value and application potential. The antioxidant activity of wolfberry polysaccharide can scavenge free radicals in the body, reduce the damage of oxidative stress to cells, and also enhance the function of the body's immune system and improve the body's resistance to pathogens. Wolfberry polysaccharide can also improve the sensitivity of pancreatic islet cells and increase the content of insulin in the serum, thereby effectively controlling the fluctuation of blood glucose values, regulating blood glucose, and helping to maintain blood glucose within the normal range.

[0003] Zinc is an essential trace element for the human body, mainly obtained through food. Compared with other trace elements, zinc is more closely related to our lives. Zinc affects physiological processes such as protein and DNA synthesis, cell growth and proliferation, hormone function, immune defense mechanisms, and metabolic regulation. However, when the human body lacks zinc, it can also be obtained through zinc supplement preparations. The common zinc supplement preparations currently are inorganic metal salts such as zinc gluconate, zinc lactate, and zinc sulfate. These zinc supplement preparations have high costs, low yields, and low zinc contents during preparation, and large doses are required to achieve the effect of supplementing zinc. By chelating polysaccharides with divalent zinc ions to prepare polysaccharide-zinc complexes to form organic zinc supplements, they have advantages such as high bioavailability, low toxicity, and easy digestion and absorption, and exhibit excellent biological activities in aspects such as antioxidant, blood glucose lowering, anti-inflammatory, antibacterial, and liver protection. In existing research, the chelation rate of polysaccharide-zinc is relatively low, and the zinc content in the complex is relatively low. Patent No. CN109776694A discloses a preparation method and application of a brown algae polysaccharide copper, iron, zinc triple chelate. The zinc content in the chelate in this patent is 8.5%. Patent No. CN112048025A discloses a water-soluble soybean polysaccharide zinc chelate zinc supplement and a preparation method and application thereof. The zinc content in the chelate in this patent is 2-3%. Patent No. CN113201078B discloses a preparation method and application of a rice bran polysaccharide zinc chelate. The zinc content in the chelate in this patent is 8-15%. Therefore, developing a zinc supplement preparation with low cost and high zinc content is of great significance for economic and medical development. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of high cost, low yield, and low zinc content in the preparation of zinc supplement preparations in the prior art. The present invention provides a wolfberry polysaccharide-zinc complex, a preparation method thereof, and an application thereof in zinc supplement preparations.

[0005] The technical solution of the present invention is as follows:

[0006] One of the objectives of the present invention is to provide a method for preparing a lycium barbarum polysaccharide-zinc complex, and the method is as follows:

[0007] S1: Dissolve the lycium barbarum polysaccharide in an HCl solution, adjust the pH value to 7 after heating in a water bath, obtain a neutral solution and cool it, then add absolute ethanol and let it stand for alcohol precipitation, centrifuge, and dry to obtain incompletely hydrolyzed lycium barbarum polysaccharide;

[0008] S2: Dissolve the incompletely hydrolyzed lycium barbarum polysaccharide obtained in S1 in distilled water to obtain a lycium barbarum polysaccharide solution;

[0009] S3: Adjust the pH value of the lycium barbarum polysaccharide solution in S2 with a dilute sulfuric acid solution, stir and dropwise add a ZnSO4 solution after heating in a water bath, perform ultrasonic treatment and then carry out a stirring reaction, cool to obtain a reaction solution, add absolute ethanol to the reaction solution and let it stand for alcohol precipitation, centrifuge, and dry to obtain a lycium barbarum polysaccharide-zinc complex.

[0010] Further defined, the specific steps of S1 are: dissolve the lycium barbarum polysaccharide with a purity of 90-99% in an HCl solution with a concentration of 1-1.5 mol / L, heat in a water bath at a temperature of 90-100 °C for 10-20 min, adjust the pH value to 7 with 6-8 mol / L NaOH, obtain a neutral solution and cool it, then add absolute ethanol and let it stand for alcohol precipitation, finally centrifuge at 5000-10000 rpm, and dry at 60-80 °C to obtain incompletely hydrolyzed lycium barbarum polysaccharide with a weight average molecular weight of 3000-4500 Da.

[0011] Further defined, the ratio of the lycium barbarum polysaccharide to the HCl solution in S1 is 1-5 g:50 mL, and the volume ratio of the absolute ethanol to the neutral solution is 3-4:1.

[0012] Further defined, the concentration of the incompletely hydrolyzed lycium barbarum polysaccharide solution in S2 is 8-12 g / L; the volume ratio of the lycium barbarum polysaccharide solution in S2 to the ZnSO4 solution in S3 is 1:1-2.

[0013] Further defined, the specific steps of S3 are: adjust the pH value of the lycium barbarum polysaccharide solution in S2 with a 0.01-0.03 mol / L dilute sulfuric acid solution, stir and dropwise add a 0.1-0.2 mol / L ZnSO4 solution after heating in a water bath at 50-80 °C, perform ultrasonic treatment and then stir for 2.5-3.5 h, cool to obtain a reaction solution, add absolute ethanol and let it stand at 4 °C for 6-12 h, finally centrifuge at 5000-10000 rpm for 5-10 min, and dry at 60-80 °C to obtain a lycium barbarum polysaccharide-zinc complex.

[0014] Further defined, the pH value in S3 is 5-6.

[0015] Further defined, in S3, the ultrasonic power is 120 - 360 W, and the ultrasonic time is 5 - 10 min.

[0016] Further defined, in S3, the volume ratio of absolute ethanol to the reaction solution is 3 - 4:1.

[0017] The second object of the present invention is to provide a wolfberry polysaccharide-zinc complex prepared by the above preparation method. In the wolfberry polysaccharide-zinc complex, the chelation rate of zinc ions is 95 - 98%, and the zinc ion content is 28 - 35%.

[0018] The third object of the present invention is to provide an application of the above wolfberry polysaccharide-zinc complex in zinc supplement preparations.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] (1) The wolfberry polysaccharide selected in the present invention is a main active ingredient of wolfberries, mainly composed of arabinose, rhamnose, xylose, mannose, galactose and glucose. The monosaccharides are linked by pyranoside bonds. The wolfberry polysaccharide contains a large number of hydroxyl groups, which can complex with zinc ions. Therefore, the present invention uses wolfberry polysaccharide and zinc sulfate as the main raw materials to prepare a wolfberry polysaccharide-zinc complex. The materials of the present invention are widely sourced, low in cost, and the preparation method is simple, which is conducive to industrial production.

[0021] (2) The present invention incompletely hydrolyzes wolfberry polysaccharide to obtain low-molecular-weight wolfberry polysaccharide with a weight-average molecular weight of about 3680 Da. The zinc ion chelation rate of the wolfberry polysaccharide-zinc complex prepared by the present invention with this smaller molecular weight can reach 95 - 98%, and the zinc content can reach 28 - 35%, which is much higher than the prior art, and the antioxidant ability is significantly improved relative to wolfberry polysaccharide. This is because after hydrolysis, the molecular weight of wolfberry polysaccharide decreases from tens of thousands of Da to several thousand Da, and the molecular conformation decomposes from macromolecules into smaller molecules, exposing more hydroxyl groups that can bind to zinc ions. On the other hand, ultrasonic treatment increases the probability of contact between zinc ions and hydroxyl groups, thereby increasing the chelation rate and zinc ion content of the complex, achieving an effect far higher than the prior art.

[0022] (3) The wolfberry polysaccharide-zinc complex prepared by the present invention has the advantages of high bioavailability, low toxicity, easy digestion and absorption, etc., and exhibits excellent biological activities in aspects such as antioxidant, hypoglycemic, anti-inflammatory, antibacterial and liver protection. Of course, it can also be used as a low-cost and high-content organic zinc supplement. Description of the Drawings

[0023] Figure 1 Chromatogram of incompletely hydrolyzed wolfberry polysaccharide prepared in Example 3;

[0024] Figure 2Comparison chart of the scavenging rates of Lycium barbarum polysaccharide and the prepared Lycium barbarum polysaccharide-zinc complex against superoxide anion radicals in Example 3;

[0025] Figure 3 Comparison chart of the scavenging rates of Lycium barbarum polysaccharide and the prepared Lycium barbarum polysaccharide-zinc complex against hydroxyl radicals in Example 3;

[0026] Figure 4 Infrared spectrum diagram of Lycium barbarum polysaccharide and the prepared Lycium barbarum polysaccharide-zinc complex in Example 3. Detailed implementation manners

[0027] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in this field, and those skilled in the art can obtain them through commercial channels without special instructions.

[0029] The terms "comprising", "including", "having", "containing" or any other variation thereof used in the following embodiments are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or elements inherent to such composition, step, method, article or device.

[0030] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value are specifically disclosed, regardless of whether the ranges are separately disclosed or not. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this application, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations can be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges contained therein.

[0031] The indefinite articles "a" and "an" before the elements or components of the present invention do not limit the quantity requirements (i.e., the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the singular form of the elements or components also includes the plural form, unless the quantity clearly refers only to the singular form.

[0032] As used herein, "one embodiment" or "an embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The appearances of "in one embodiment" in different places in this specification do not necessarily refer to the same embodiment, nor are they separate or alternative embodiments that are mutually exclusive of other embodiments.

[0033] The endpoints and any values in the ranges disclosed in the invention are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0034] Example 1:

[0035] Weigh 2 g of wolfberry polysaccharide with a purity of 90 - 99%. Dissolve it in 50 mL of HCl solution (1 mol / L), heat it in a water bath at 95 °C for 15 min, adjust the pH to neutral with 6 mol / L NaOH to obtain a neutral solution. After cooling to room temperature, add anhydrous ethanol with a volume 4 times that of the neutral solution, let it stand at 4 °C for 8 h, centrifuge at 10000 rpm, and dry it in an oven at 70 °C to obtain incompletely hydrolyzed wolfberry polysaccharide.

[0036] Dissolve 100 mg of incompletely hydrolyzed wolfberry polysaccharide in 10 mL of distilled water to obtain a wolfberry polysaccharide solution. Adjust the pH value of the wolfberry polysaccharide solution to 5.5 with 0.02 mol / L dilute sulfuric acid, heat it in a water bath at 50 °C, drop in 15 mL of ZnSO4 (0.1 mol / L) solution, ultrasonicate at a power of 240 W for 8 min, continue the reaction for 3 h to obtain a reaction solution. After cooling to room temperature, add anhydrous ethanol with a volume 4 times that of the reaction solution, let it stand at 4 °C for 8 h, centrifuge at 8000 rpm for 5 min to obtain a precipitate. Place the precipitate in an oven at 70 °C to dry and obtain a wolfberry polysaccharide-zinc complex.

[0037] Example 2:

[0038] Weigh 2 g of wolfberry polysaccharide with a purity of 90 - 99%, dissolve it in 50 mL of HCl solution (1 mol / L), heat it in a water bath at 95 °C for 15 min, adjust the pH to neutral with 6 mol / L NaOH to obtain a neutral solution. After cooling to room temperature, add anhydrous ethanol with a volume 4 times that of the neutral solution, let it stand at 4 °C for 8 h, centrifuge at 10000 rpm, and dry it in an oven at 70 °C to obtain incompletely hydrolyzed wolfberry polysaccharide;

[0039] Dissolve 100 mg of incompletely hydrolyzed wolfberry polysaccharide in 10 mL of distilled water to obtain a wolfberry polysaccharide solution. Adjust the pH value of the wolfberry polysaccharide solution to 5.2 with 0.02 mol / L dilute sulfuric acid, heat it in a water bath at 60 °C, drop in 10 mL of ZnSO4 (0.1 mol / L) solution, ultrasonicate at a power of 360 W for 5 min, continue the reaction for 3 h to obtain a reaction solution. After cooling to room temperature, add anhydrous ethanol with a volume 4 times that of the reaction solution, let it stand at 4 °C for 8 h, centrifuge at 8000 rpm for 5 min to obtain a precipitate, and dry the precipitate in an oven at 70 °C to obtain wolfberry polysaccharide-zinc complex.

[0040] Example 3:

[0041] Weigh 2 g of wolfberry polysaccharide with a purity of 90 - 99%, dissolve it in 50 mL of HCl solution (1 mol / L), heat it in a water bath at 95 °C for 15 min, adjust the pH to neutral with 6 mol / L NaOH to obtain a neutral solution. After cooling to room temperature, add anhydrous ethanol with a volume 4 times that of the neutral solution, let it stand at 4 °C for 8 h, centrifuge at 10000 rpm, and dry it in an oven at 70 °C to obtain incompletely hydrolyzed wolfberry polysaccharide;

[0042] Dissolve 100 mg of incompletely hydrolyzed wolfberry polysaccharide in 10 mL of distilled water to obtain a wolfberry polysaccharide solution. Adjust the pH value of the wolfberry polysaccharide solution to 5.5 with 0.02 mol / L dilute sulfuric acid, heat it in a water bath at 70 °C, drop in 15 mL of ZnSO4 (0.1 mol / L) solution, ultrasonicate at a power of 120 W for 10 min, continue the reaction for 2.5 h to obtain a reaction solution. After cooling to room temperature, add anhydrous ethanol with a volume 4 times that of the reaction solution, let it stand at 4 °C for 8 h, centrifuge at 8000 rpm for 5 min to obtain a precipitate, and dry the precipitate in an oven at 70 °C to obtain wolfberry polysaccharide-zinc complex.

[0043] Comparative Example 1:

[0044] The difference between Comparative Example 1 and Example 1 is that the pH value of the wolfberry polysaccharide solution is adjusted to 4.5 with 0.02 mol / L dilute sulfuric acid, and other parameters and steps are the same as those in Example 1.

[0045] Comparative Example 2:

[0046] The difference between Comparative Example 2 and Example 2 is that 5 mL of ZnSO4 (0.1 mol / L) solution was dropped in, and other parameters and steps were the same as those in Example 2.

[0047] Comparative Example 3:

[0048] The difference between Comparative Example 3 and Example 3 is that the water bath temperature after adjusting the wolfberry polysaccharide solution with 0.02 mol / L dilute sulfuric acid was 40 °C, and other parameters and steps were the same as those in Example 3.

[0049] Comparative Example 4:

[0050] The difference between Comparative Example 4 and Example 1 is that ultrasonic treatment was not carried out, and other parameters and steps were the same as those in Example 1.

[0051] Comparative Example 5:

[0052] The difference between Comparative Example 5 and Example 3 is only that chelation reaction was carried out using unhydrolyzed wolfberry polysaccharide and zinc sulfate, and other parameters and steps were the same as those in Example 3.

[0053] Figure 1 Chromatogram of incompletely hydrolyzed wolfberry polysaccharide prepared for Example 3. The molecular weight of wolfberry polysaccharide after hydrolysis was determined by gel filtration chromatography, and the results were as Figure 1 shown. From Figure 1 we can see that the weight-average molecular weight of the incompletely hydrolyzed wolfberry polysaccharide was 3688 Da.

[0054] The chelation rate of zinc and the zinc content in the wolfberry polysaccharide-zinc complexes of Examples 1-3 and Comparative Examples 1-5 were detected:

[0055] The content of free Zn 2+ in the reaction system was determined by the EDTA titration method. The specific method was as follows: Take 1 mL of the reaction solution before alcohol precipitation of the wolfberry polysaccharide-zinc complexes prepared in Examples 1-3 and Comparative Examples 1-5, adjust the pH value of the solution to 7-8 with 10% ammonia water, add 0.2 mL of ammonia-ammonium chloride buffer solution, drop in one drop of eriochrome black T indicator, shake well, and immediately titrate slowly with the EDTA standard solution. Calculate the content of free Zn 2+ in the reaction system according to the following formula (1), and calculate the chelation rate of the wolfberry polysaccharide-zinc complex according to the following formula (2).

[0056]

[0057] (1) In the formula: C1 represents the concentration of free Zn 2+ , C0 represents the concentration of the EDTA standard solution, V1 represents the total volume of the solution before titration, and V0 represents the volume of the consumed EDTA standard solution.

[0058]

[0059] (2) In the formula: C1 represents the concentration of free Zn 2+ and C2 represents the concentration of added Zn 2+ .

[0060] The zinc content in the lycium barbarum polysaccharide-zinc complexes prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was determined according to the standard GB 5009.14-2017 "National Food Safety Standard - Determination of Zinc in Foods", and the results are shown in Table 1

[0061] Table 1 Chelation rate and zinc content of zinc in the lycium barbarum polysaccharide-zinc complexes of Examples 1 to 3 and Comparative Examples 1 to 5

[0062] Zinc ion chelation rate Zinc content in the complex Example 1 96.7％ 32.3％ Example 2 95.3％ 30.7％ Example 3 97.5％ 34.2％ Comparative Example 1 78.3％ 22.3％ Comparative Example 2 43.6％ 13.6％ Comparative Example 3 83.8％ 24.7％ Comparative Example 4 87.4％ 26.7％ Comparative Example 5 88.6％ 27.2％

[0063] It can be seen from Table 1 that the chelation rates of zinc in the lycium barbarum polysaccharide-zinc complexes prepared in Examples 1 to 3 are all greater than 95%, and the zinc contents are all greater than 30%. While the chelation rates of zinc in the lycium barbarum polysaccharide-zinc complexes prepared in Comparative Examples 1 to 5 are all less than 90%, and the zinc contents are all less than 28%. And there is only a difference in a certain parameter between Comparative Examples 1 to 5 and Examples 1 to 3, which proves that the technical solution of the present invention can effectively improve the chelation rate and zinc content of zinc in the lycium barbarum polysaccharide-zinc complex

[0064] Determination of superoxide anion radical scavenging ability:

[0065] Take the lycium barbarum polysaccharide-zinc complex prepared in Example 3, prepare solutions of different concentrations of lycium barbarum polysaccharide and lycium barbarum polysaccharide-zinc complex (0.2, 0.4, 0.6, 0.8, 1.0 mg / mL). Take 1 mL of each sample and add 4.5 mL of Tris-HCL buffer solution (50 mmol / L, pH value 8.2), and mix well. After reacting for 20 min under the water bath condition at 25 °C, add 0.1 mL of pyrogallol solution (3 mmol / L), continue to react in the water bath at 25 °C for 5 min, then take out and add 1 mL of 8 mmol / L hydrochloric acid to terminate the reaction. Use a visible spectrophotometer to measure the absorbance value A1 of the solution at a wavelength of 320 nm. Use distilled water as the blank control to measure the absorbance A0, and use 0.1 mL of distilled water instead of the pyrogallol solution (3 mmol / L) to measure the absorbance value as A2. The formula for calculating the superoxide anion radical scavenging rate is as follows:

[0066]

[0067] Figure 2 It is a comparison chart of the superoxide anion radical scavenging rates of the lycium barbarum polysaccharide and the prepared lycium barbarum polysaccharide-zinc complex in Example 3. From Figure 2It can be seen that at the same concentration, the ability of the Lycium barbarum polysaccharide-zinc complex to scavenge superoxide anion radicals is better than that of Lycium barbarum polysaccharide. This is because after the combination of Lycium barbarum polysaccharide and Zn 2+ After binding, the intermediate formed by the reaction of the Lycium barbarum polysaccharide-zinc complex with free radicals is more stable. Therefore, the Lycium barbarum polysaccharide-zinc complex has a stronger ability to scavenge free radicals and is more beneficial to human health.

[0068] Determination of hydroxyl radical scavenging ability:

[0069] Take the Lycium barbarum polysaccharide-zinc complex prepared in Example 3, and prepare solutions of different concentrations of Lycium barbarum polysaccharide and Lycium barbarum polysaccharide-zinc complex (0.2, 0.4, 0.6, 0.8, 1.0 mg / mL) respectively. Take 1 mL of the sample solution and add 1 mL of ferrous sulfate solution (9 mmol / L) and 1 mL of salicylic acid solution (9 mmol / L). After mixing well, let it stand at room temperature for 5 min, then add 1 mL of H2O2 solution (8.8 mmol / L). After mixing well, react in a water bath at 37 °C for 30 min. Use a visible spectrophotometer to measure the absorbance A1 of the solution at a wavelength of 510 nm. Use distilled water as a blank control to measure the absorbance A0, and use 1 mL of distilled water instead of adding 1 mL of H2O2 solution (8.8 mmol / L) to measure the absorbance A2. The formula for calculating the hydroxyl radical scavenging rate is as follows:

[0070]

[0071] Figure 3 It is a comparison chart of the hydroxyl radical scavenging rates of the Lycium barbarum polysaccharide of Example 3 and the prepared Lycium barbarum polysaccharide-zinc complex. From Figure 3 It can be seen that at the same concentration, the ability of the Lycium barbarum polysaccharide-zinc complex to scavenge hydroxyl radicals is significantly better than that of Lycium barbarum polysaccharide. This is because when Lycium barbarum polysaccharide binds to zinc ions, the formed coordination structure enhances the interaction with the exposed active groups, thereby strengthening the reaction efficiency with free radicals.

[0072] Figure 4 It is the infrared spectrum diagram of the Lycium barbarum polysaccharide of Example 3 and the prepared Lycium barbarum polysaccharide-zinc complex. As Figure 4 shown, both the Lycium barbarum polysaccharide and the Lycium barbarum polysaccharide-zinc complex have typical characteristic absorption peaks of polysaccharides. The Lycium barbarum polysaccharide has a vibration absorption peak of -OH in the polysaccharide molecule at a wavelength of 3434.76 cm -1 A stretching vibration peak of C=O at a wavelength of 1633.79 cm -1 A vibration absorption peak of C-H near a wavelength of 1400.95 cm -1 And a vibration absorption peak of C-H at a wavelength of 1063.49 cm -1The strong absorption peak at [specific location] belongs to the asymmetric vibration of C-O-C or C-O-H on the sugar ring and is the characteristic absorption peak of pyranose. Generally speaking, the parameters and shapes of the two are relatively similar, indicating that the chelation of zinc does not damage the basic structure of wolfberry polysaccharide. In addition, after zinc chelation, the peaks originally at wavelengths 3434.76 cm -1 and 1063.49 cm -1 were redshifted to 3489.6 cm -1 and 1113.81 cm -1 respectively, indicating that some absorption peaks were redshifted after complexation. A new sharp absorption peak appears at 618.24 cm -1 of the wolfberry polysaccharide-zinc complex, which is caused by the bending vibration of the Zn-O bond. The changes in these peak shapes and the formation of new absorption peaks all indicate the formation of a complex between zinc ions and wolfberry polysaccharide, proving the successful preparation of the present invention.

[0073] As mentioned above, the above are only the preferred specific embodiments of the present invention. These specific embodiments are all different implementation manners based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A preparation method of a wolfberry polysaccharide-zinc complex, characterized in that, The method: S1: Dissolve wolfberry polysaccharide in HCl solution, adjust the pH value to 7 after water bath heating, obtain a neutral solution and cool it, then add absolute ethanol and let it stand for alcohol precipitation, centrifuge, and dry to obtain incompletely hydrolyzed wolfberry polysaccharide; S2: Dissolve the incompletely hydrolyzed wolfberry polysaccharide obtained in S1 in distilled water to obtain a wolfberry polysaccharide solution; S3: Use dilute sulfuric acid solution to adjust the pH value of the wolfberry polysaccharide solution in S2, stir and dropwise add ZnSO4 solution after heating up in a water bath, carry out ultrasonic treatment and then stir and react, cool to obtain a reaction solution, add absolute ethanol to the reaction solution and let it stand for alcohol precipitation, centrifuge, and dry to obtain a wolfberry polysaccharide-zinc complex.

2. The method according to claim 1, characterized in that, The specific steps of S1 are: Dissolve wolfberry polysaccharide with a purity of 90-99% in HCl solution with a concentration of 1-1.5 mol / L, heat in a water bath at 90-100 °C for 10-20 min, adjust the pH value to 7 with 6-8 mol / L NaOH, obtain a neutral solution and cool it, then add absolute ethanol and let it stand at 4 °C for 6-12 h, finally centrifuge at 5000-10000 rpm, and dry at 60-80 °C to obtain incompletely hydrolyzed wolfberry polysaccharide with a weight average molecular weight of 3000-4500 Da.

3. The method according to claim 1 or 2, characterized in that, In S1, the ratio of wolfberry polysaccharide to HCl solution is 1-5 g:50 mL, and the volume ratio of absolute ethanol to the neutral solution is 3-4:

1.

4. The method according to claim 1, characterized in that, In S2, the concentration of the incompletely hydrolyzed wolfberry polysaccharide solution is 8-12 g / L; the volume ratio of the wolfberry polysaccharide solution in S2 to the ZnSO4 solution in S3 is 1:1-2.

5. The method according to claim 1, characterized in that The specific steps of S3 are: Use 0.01-0.03 mol / L dilute sulfuric acid solution to adjust the pH value of the wolfberry polysaccharide solution in S2, stir and dropwise add 0.1-0.2 mol / L ZnSO4 solution after heating up to 50-80 °C in a water bath, stir for 2.5-3.5 h after ultrasonic treatment, cool to obtain a reaction solution, add absolute ethanol to the reaction solution and let it stand at 4 °C for 6-12 h, finally centrifuge at 5000-10000 rpm for 5-10 min, and dry at 60-80 °C to obtain a wolfberry polysaccharide-zinc complex.

6. The method according to claim 1 or 5, characterized in that, In S3, the pH value is 5-6.

7. The method according to claim 1 or 5, characterized in that, In S3, the ultrasonic power is 120-360 W, and the ultrasonic time is 5-10 min.

8. The method according to claim 1 or 5, characterized in that, In S3, the volume ratio of absolute ethanol to the reaction solution is 3-4:

1.

9. The lycium barbarum polysaccharide-zinc complex prepared by the method according to any one of claims 1 to 8, characterized in that, In the wolfberry polysaccharide-zinc complex, the chelation rate of zinc ions is 95-98%, and the zinc ion content is 28-35%.

10. Use of the wolfberry polysaccharide-zinc complex according to claim 9 in a zinc supplement preparation.

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