CN109206531B

CN109206531B - Polysaccharide P2, separation and purification method thereof and application thereof in preparation of hypolipidemic drugs

Info

Publication number: CN109206531B
Application number: CN201810987144.9A
Authority: CN
Inventors: 黄儒强; 王静辉; 王倩; 高林林; 张竞雯
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2018-08-28
Filing date: 2018-08-28
Publication date: 2021-06-04
Anticipated expiration: 2038-08-28
Also published as: CN109206531A

Abstract

The invention discloses a myrtle polysaccharide P2, a separation and purification method thereof and application thereof in preparing a blood fat reducing medicament, wherein the polysaccharide comprises monosaccharide in the following molar percentage: 8.25 percent of ribose, 2.10 percent of rhamnose, 53.75 percent of arabinose, 5.16 percent of xylose, 8.22 percent of mannose, 12.01 percent of glucose and 10.51 percent of galactose. The experimental result shows that the myrtle polysaccharide P2 has a certain capacity of combining cholate in vitro, cholestyramine is used as a positive control, and the relative combination rates of the myrtle polysaccharide P2 to sodium taurocholate, sodium glycocholate and sodium cholate are respectively calculated according to the combination rate of the cholestyramine to each cholate as 100 percent: 29.87%, 47.49% and 53.69%.

Description

Polysaccharide P2, separation and purification method thereof and application thereof in preparation of hypolipidemic drugs

Technical Field

The invention belongs to the field of natural products (medicines), and particularly relates to myrtle polysaccharide P2, a separation and purification method thereof, and application of myrtle polysaccharide P2 in preparation of a blood fat reducing medicine.

Background

Myrtle (Rhodomyrtus tomentosa), also known as Rhodomyrtus tomentosa (Guangdong), dried Dodong (Guangxi), Psychotria mollis (Bencao Shiyi), Anlungzi (Ling exterior recorded Exclusion), Anlungzi (Susheng Fangfang), etc., which are widely distributed in the tropical region of south Asia; the method is characterized in that the method takes an evergreen broad-leaved forest ecosystem as a dominant species, the coverage is 30-60%, and the dominant species are pioneer communities; the wild myrtle is mainly distributed in the south of the mountains in China, is a main under-forest vegetation in the southern region of China, is rich in resources, mostly grows on hilly slopes, fields and roadside, is wide in distribution area, but is low in development and utilization rate and low in processing and utilization level at present, and belongs to a potential new food resource which is not developed and utilized in a large scale.

The fruit of the myrtle is berry, the peel is purple black when the myrtle is ripe, the pulp is purple red, the pulp is succulent, and the nutrition is rich. Research shows that when the wild myrtle fruits ripen, the total sugar content accounts for 8.06%, the reducing sugar accounts for 7.72%, the pectin accounts for 1.01%, the total acid accounts for 0.38%, the protein accounts for 1.30%, the fat accounts for 0.32%, the starch accounts for 3.08%, the crude fiber accounts for 34.97%, and the vitamin C content is 5.48 mg/kg.

The myrtle fruit contains various active ingredients such as polysaccharides, flavonoids, saponins, polyphenols, anthraquinones, etc., and has biological activities such as antioxidation, anti-aging, anti-inflammatory, antibacterial, and liver protection. As a wild plant resource, the myrtle has wide development prospects in the aspects of food processing, health-care product development, medical drug research and the like.

Disclosure of Invention

The invention aims to provide the myrtle polysaccharide P2 which has high purity and bioactivity.

The invention also aims to provide a method for separating and purifying the polysaccharide P2, which is to extract the polysaccharide from the myrtle fruits by a water extraction and alcohol precipitation method and separate and purify the polysaccharide by an ion exchange column chromatography method.

The invention also aims to provide the application of the polysaccharide P2 in preparing the hypolipidemic medicament.

The purpose of the invention is realized by the following technical scheme:

a myrtle polysaccharide P2 comprises the following monosaccharides in mole percentage: 8.25% of ribose, 2.10% of rhamnose, 53.75% of arabinose, 5.16% of xylose, 8.22% of mannose, 12.01% of glucose and 10.51% of galactose; the monosaccharide composition is calculated by a GC-MS area normalization method, all peak areas except a solvent peak are regarded as 100%, and the percentage of the main peak area in the total area is calculated;

the number average molecular weight (Mn) of the myrtle polysaccharide P2 is 2.57 × 10⁴Da, weight average molecular weight (Mw) of 6.75X 10⁴Da。

The method for separating and purifying myrtle polysaccharide P2 comprises the following steps:

(1) extracting myrtle fruit polysaccharide: drying and crushing myrtle fruits, boiling and extracting dry powder and distilled water in a reflux device for several times, combining extracting solutions, concentrating under reduced pressure, adding 95% (V/V) ethanol with a volume being several times that of the concentrated solution, continuously stirring to enable polysaccharide to be uniformly precipitated, standing for more than 12 hours at 4 ℃, centrifugally collecting precipitates, and drying to obtain crude myrtle fruit polysaccharide;

boiling and extracting in the step (1), wherein the extraction time of each time is preferably 4 h;

the centrifugation of the step (1) is preferably carried out for 15min at 5000 r/min;

(2)H₂O₂and (3) decoloring by a method: dissolving crude polysaccharide of Myrtus communis fruit in distilled water, adjusting pH to 8.0, and adding 30% H dropwise₂O₂Stirring the solution until the color of the solution becomes light, and then preserving the temperature for 2 hours in a water bath at 50 ℃;

the concentration of the crude polysaccharide dissolved by adding distilled water in the step (2) is preferably 0.2 g/mL;

(3) deproteinization by the Sevag method: adding Sevag reagent with the volume of 1/5 into the decolorized polysaccharide solution, performing shaking culture for 20min, standing for 10min, centrifuging, discarding gel substances generated by lower organic phase and middle protein, chloroform and n-butanol, and repeating the centrifuging and discarding operations for several times; after the last operation, removing the residual Sevag reagent in the solution by rotary evaporation to obtain a deproteinized myrtle fruit polysaccharide solution, collecting precipitates according to the alcohol precipitation method in the step (1), and drying to obtain primarily purified myrtle fruit polysaccharide;

the Sevag reagent in the step (3) consists of chloroform and n-butanol according to the volume ratio of 5: 1;

the shaking culture in the step (3) is carried out, and the rotation speed is preferably 150 r/min;

the centrifugation of the step (3) is preferably carried out for 10min at 4000 r/min;

(4) and (3) carrying out DEAE-Sepharose fast flow ion exchange column chromatography to separate myrtle fruit polysaccharide: pre-treating DEAE-sepharose gel filler, loading the filler into a column, dissolving the preliminarily purified myrtle fruit polysaccharide obtained in the step (3) by using deionized water, passing the solution through a 0.45-micrometer microporous filter membrane, and loading the solution into the column; eluting with distilled water, eluting per 0.1g of myrtle fruit polysaccharide with 150mL of distilled water, and collecting no fraction; then eluting with NaCl solution with the concentration of 0.1mol/L, collecting one tube of eluent every 5mL, detecting the absorbance value of the eluent at the detection wavelength of 490nm by using a phenol-sulfuric acid method, stopping collecting until the absorbance value is close to zero, merging fractions, concentrating, dialyzing, and freeze-drying to obtain polysaccharide P2;

the filler pretreatment in the step (4) comprises the following steps: carrying out suction filtration on the filler and washing the filler by using distilled water, and then carrying out defoaming by using ultrasonic waves and standing the filler because bubbles are generated in the washing process;

the column filling step (4) comprises the following steps: slowly draining the filler into a chromatographic column (the column specification is 1.5cm multiplied by 20cm), wherein the volume of a column bed is about 20 mL; washing the chromatographic column with distilled water for 1h, then washing with a NaCl solution with the concentration of 1mol/L for 1h, and finally washing with distilled water for 2h to prepare for sample loading;

dissolving the primarily purified myrtle fruit polysaccharide in deionized water, wherein the concentration of the primarily purified myrtle fruit polysaccharide is preferably 50 mg/mL;

the loading and elution flow rate in step (4) is preferably 0.5 mL/min.

And (4) carrying out dialysis, namely transferring the concentrated fraction into a dialysis bag (3000Da) to dialyze for 48h at 4 ℃.

The myrtle polysaccharide P2 has the function of reducing blood fat, and can be used for preparing a blood fat reducing medicine;

the medicine also comprises acceptable auxiliary materials and other effective components which play a compatible and synergistic effect;

the medicine can be made into various dosage forms, such as tablets, granules, capsules, dripping pills, sustained release preparations, oral liquid, injections and the like.

The experimental result of the invention shows that the myrtle polysaccharide P2 has a certain capacity of combining cholate in vitro, cholestyramine (a blood fat reducing drug, the mechanism of reducing blood fat is namely combining cholate) is taken as a positive control, the relative combination rates of the myrtle polysaccharide P2 to sodium taurocholate, sodium glycocholate and sodium cholate are converted according to the calculation that the combination rate of the cholestyramine to each cholate is 100 percent: 29.87%, 47.49% and 53.69%. The experimental result preliminarily shows that the myrtle polysaccharide P2 has a certain effect of reducing blood fat.

The invention obtains the crude polysaccharide of the myrtle fruit by a water extraction and alcohol precipitation method, adopts H₂O₂The method is decolorized and deproteinized by a Sevag method, and separation and purification are carried out by using a DEAE-Sepharose fast flow ion exchange chromatographic column, and compared with the prior art, the method has the following advantages and effects:

(1) the invention establishes a complete and feasible technical route for extracting, separating and purifying the myrtle fruit polysaccharide and researching the structural characteristics and the biological activity, and provides technical guidance for extracting, separating and purifying the myrtle fruit polysaccharide which is a wild plant resource.

(2) The water extraction and alcohol precipitation method can complete a large amount of polysaccharide extraction operation, has low cost, good repeatability and high yield, and is suitable for industrial large-scale production.

(3) The DEAE-Sepharose fast flow used in the invention has better physical and chemical stability and mechanical properties, large exchange capacity, can be cleaned in place, has small change of bed volume along with the ionic strength of pH value, and is suitable for purifying a large amount of crude products due to high flow rate and loading capacity.

(4) The invention creatively combines the water extraction and alcohol precipitation extraction method of the polysaccharide with the ion exchange chromatography separation and purification method for researching the myrtle fruit polysaccharide, compares and obtains better process parameters, and provides technical guidance and a new thought for the extraction, separation and purification of the myrtle fruit polysaccharide.

Drawings

FIG. 1 is a graph showing the elution profile of Myrtus communis fruit polysaccharides.

FIG. 2 is a UV spectrum of polysaccharide P2.

FIG. 3 shows the in vitro binding capacity of Myrtus communis fruit polysaccharides to cholate.

FIG. 4 is an infrared spectrum of polysaccharide P2.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

In the examples, the analysis of the polysaccharide fraction P2 of the obtained Myrtus communis fruit was performed by the Guangzhou analysis test center of China, and the report numbers are 2017011500-3, respectively.

Example 1

A method for extracting, separating and purifying polysaccharide from myrtle fruits comprises the following steps:

(1) extracting myrtle fruit polysaccharide: weighing 110g of dried myrtle fruits, crushing, sieving with a 40-mesh sieve, weighing 100g of dry powder, adding 1000mL of distilled water, boiling for 4h in a reflux device, carrying out suction filtration, taking filter residues, adding 1000mL of distilled water, boiling for 4h in the reflux device, combining supernate, and concentrating under reduced pressure. Slowly adding 4 times volume of 95% (V/V) ethanol into the concentrated solution, continuously stirring with a glass rod to uniformly precipitate polysaccharide, standing in a refrigerator at 4 deg.C for 12h, centrifuging at 5000r/min for 15min, collecting precipitate, and oven drying to obtain crude polysaccharide of Myrtus communis fruit;

(2)H₂O₂and (3) decoloring by a method: weighing 20g of crude myrtle fruit polysaccharide, dissolving in 100mL of distilled water, adjusting pH to 8.0 with 1% NaOH solution, and adding 30% H dropwise₂O₂Stirring the solution until the color gradually becomes lighter, and then preserving the temperature for 2 hours in a water bath at 50 ℃;

(3) deproteinization by the Sevag method: adding Sevag reagent (prepared by chloroform and n-butanol at a volume ratio of 5: 1) 1/5 times the volume of the solution into decolorized polysaccharide solution, shaking on a shaking table at a rotation speed of 150r/min for 20min, standing for 10min, centrifuging, discarding gel formed by lower layer organic phase and middle layer protein, chloroform and n-butanol, and repeating for 5 times. Centrifuging at 4000r/min for 10min at the last time, then removing residual Sevag reagent in the solution by rotary evaporation to obtain deproteinized myrtle fruit polysaccharide solution, collecting precipitate by the alcohol precipitation method in the step (1), and drying to obtain primarily purified myrtle fruit polysaccharide;

(4) and (3) carrying out DEAE-Sepharose fast flow ion exchange column chromatography to separate myrtle fruit polysaccharide:

4.1 filler pretreatment: in order to remove the 20% ethanol protective solution, the solution was washed with distilled water during suction filtration. Bubbles are generated in the flushing process, and then ultrasonic waves are used for defoaming and standing;

4.2, column filling: the seasoning was slowly drained into a chromatography column (column size 1.5 cm. times.20 cm) with a bed volume of about 20 mL. Washing the chromatographic column with distilled water for 1h, then washing with a NaCl solution with the concentration of 1mol/L for 1h, and finally washing with distilled water for 2h to prepare for sample loading;

4.3, loading: taking 0.1g of polysaccharide sample, dissolving with 2mL of distilled water to prepare a solution with the concentration of 50mg/mL, and loading the solution at the flow rate of 0.5mL/min after passing through a 0.45-micron microporous filter membrane;

4.4 elution: eluting with 150mL of distilled water, then eluting with 0.1mol/L NaCl solution, collecting one tube of eluent every 5mL, measuring the polysaccharide content of each tube by a phenol-sulfuric acid method, and determining that the collection is finished when no polysaccharide is detected. The number of the received tubes was used as the abscissa and the absorbance at 490nm was used as the ordinate to plot the elution curve, i.e., FIG. 1;

the concrete operation of detecting the polysaccharide content by a phenol-sulfuric acid method is as follows: accurately transferring 0.1mg/mL anhydrous glucose standard solution 0, 0.2, 0.4, 0.6, 0.8 and 1.0mL, sequentially placing in 6 test tubes, sequentially adding distilled water 1.0, 0.8, 0.6, 0.4, 0.2 and 0mL, sequentially adding 6% phenol solution 0.5mL and concentrated sulfuric acid 2.5mL, mixing uniformly, standing at room temperature for 20min, measuring absorbance at 490nm, and drawing a standard curve with glucose concentration as abscissa and absorbance as ordinate. Measuring 1mL of sample solution, measuring corresponding absorbance according to a standard curve operation method, and calculating the content of total polysaccharide in the sample solution.

4.5, dialysis: collecting the eluted components, concentrating, dialyzing in dialysis bag (3000Da) at 4 deg.C for 48 hr, concentrating under reduced pressure, and freeze drying to obtain Myrtus communis fruit polysaccharide P2.

Example 2

Ultraviolet spectrum analysis is carried out on the myrtle fruit polysaccharide P2 obtained in the example 1, 1mg of polysaccharide sample is weighed, 1mg/mL of polysaccharide solution is prepared, and an ultraviolet spectrum within the range of 200-500nm is scanned.

FIG. 2 is a UV spectrum of P2, showing that the component has no obvious absorption peak at 260nm and 280nm, indicating that it contains no protein and nucleic acid substances.

Example 3

Polysaccharide molecular weight analysis was performed on myrtle fruit polysaccharide P2 obtained in example 1, and the specific experimental method was as follows:

the molecular weight was determined by Gel Permeation Chromatography (GPC). Taking 2mg of polysaccharide sample, adding 0.02mol/L phosphate buffer solution for dissolving to prepare 2.0mg/mL solution, filtering with a sterile filter membrane of 0.22 mu m, and taking the filtered clear solution for later use. Chromatographic conditions are as follows: the column temperature is 35 ℃, 0.02mol/L phosphate buffer solution is used as a mobile phase, the flow rate is 0.6mL/min, the sample injection amount is 20 mu L, and Waters 2410 is used for detection by a differential refraction detector. A series of dextran solutions (700, 400, 200, 100, 50, 30, 10, 5kD) of different molecular weights were prepared as standards and standard curves were plotted, and the sample molecular weights were calculated from their corresponding elution volumes against the standard curve.

The measured molecular weight of myrtle fruit polysaccharide P2 is shown in Table 1 below:

TABLE 1 molecular weight of Myrtus communis fruit polysaccharide P2

Example 4

Monosaccharide composition analysis is performed on myrtle fruit polysaccharide P2 obtained in example 1, and the specific method is as follows:

weighing 10mg of polysaccharide sample, adding 5mL of 4mol/L trifluoroacetic acid, hydrolyzing at 100 ℃ for 2h, blow-drying the hydrolysate by using a nitrogen blowing instrument, and washing for 3 times by using chromatographic pure methanol to obtain the polysaccharide hydrolysate. 10mg of hydroxylamine hydrochloride, 1mg of internal standard inositol and 2mL of pyridine are sequentially added into the polysaccharide hydrolysate, 2mL of acetic anhydride is added after water bath at 90 ℃ for 30min, and 2mL of distilled water is added after water bath at 90 ℃ for 30min to terminate the reaction. The mixture was extracted 2 times with 2mL of dichloromethane, the dichloromethane phases were combined, dried over anhydrous sodium sulfate and filtered through a 0.22 μm organic microfiltration membrane for further use.

Gas chromatography detection conditions: the analytical column was HP-5MS (30 m.times.0.25 mm.times.0.25 μm); the sample injection volume is 1 mu L; the temperature of a sample inlet is 250 ℃; the constant voltage mode is 20 PSI; temperature programming: the initial column temperature is 100 ℃, the temperature is kept for 0.5min, then the temperature is raised to 140 ℃ at the speed of 20 ℃/min, the temperature is kept for 5min, then the temperature is raised to 160 ℃ at the speed of 3 ℃/min, and then the temperature is raised to 250 ℃ at the speed of 10 ℃/min, and the temperature is kept for 5 min; the split ratio is 10:1, the mobile phase is helium, and the flow rate is 1 mL/min.

And (3) detecting a monosaccharide standard: and (3) taking ribose, rhamnose, arabinose, xylose, mannose, glucose and galactose standard substances, and carrying out treatment and detection according to the same steps to serve as standard controls.

The monosaccharide composition of the myrtle fruit polysaccharide P2 was determined and the results are shown in Table 2 below:

TABLE 2 monosaccharide composition of Myrtus communis fruit polysaccharide P2

Example 5

Fourier infrared spectroscopy analysis was performed on myrtle fruit polysaccharide P2 obtained in example 1:

weighing 2mg polysaccharide sample, mixing with dried KBr (potassium bromide) in mortar, grinding, tabletting with tablet machine, and performing Fourier transform infrared spectrometer at 400-4000cm^-1Is scanned over a range of wavenumbers.

The functional group has a characteristic absorption peak in the infrared spectrogram, so the infrared spectrogram can better analyze the structure of the polysaccharide. FIG. 4 is an infrared spectrum of purified fraction P2 of Myrtus communis fruit polysaccharide at 3402cm^-1The absorption peak is generated by O-H stretching vibration, and is 2930cm^-1The absorption peak is generated by C-H stretching vibration, 1385cm^-1The absorption peaks at (B) are caused by C-O stretching vibration, and these peaks are characteristic peaks of polysaccharides, and P2 can be judged to belong to polysaccharide substances.

The infrared spectrum of P2 (FIG. 4) is 1152cm^-1The absorption peak at (b) indicates the presence of a pyranose ring in P2; at 1049cm^-1The absorption peak at (a) indicates the presence of a glucose unit.

Example 6

In-vitro cholate binding capacity determination is carried out on the myrtle fruit polysaccharide P2 obtained in example 1, cholestyramine is used as a positive control, and the blood fat reducing capacity is preliminarily characterized. The measurement method is as follows:

drawing a standard curve of cholate: sodium taurocholate, sodium glycocholate and sodium cholate were prepared in 0.1mol/L, pH ═ 6.3 phosphate buffer, respectively, at 0.3 mmol/L. 0, 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5mL of the above solutions were put in a 10mL test tube with a stopper, 0.1mol/L, pH ═ 6.3 phosphoric acid buffer solution was added to 2.5mL, then 7.5mL of 60% sulfuric acid solution was added, and the mixture was put in a 70 ℃ water bath for 20min, taken out and put in an ice bath for 5min, and absorbance at 387nm wavelength was measured. And drawing standard curves of various cholates by taking the cholate concentration as an abscissa and the absorbance as an ordinate.

The sample simulates the human gastrointestinal tract environment: 1mL of the sample solution was put in a 10mL stoppered test tube, and 1mL of a 0.01mol/L hydrochloric acid solution was added thereto, and digested at 37 ℃ for 1 hour with shaking, followed by adjusting the pH to 6.3 with a 0.1mol/L sodium hydroxide solution, and 4mL of 10mg/mL pancreatin (prepared with a 0.1mol/L phosphate buffer solution having a pH of 6.3) was added thereto, and digested at 37 ℃ for 30 minutes with shaking.

In vitro cholate binding experiments: respectively adding 4mL of various cholate (sodium taurocholate, sodium glycocholate and sodium cholate) solutions of 0.3mmol/L into the sample solution processed by simulating the human gastrointestinal tract environment, oscillating at a constant temperature of 37 ℃ for 1h, transferring into a centrifuge tube, and centrifuging at 4000r/min for 20 min. The cholate content of the supernatant was analyzed: respectively taking 2.5ml of the supernatant, placing in a test tube with a plug, adding 7.5ml of 60% sulfuric acid solution, placing in a 70 deg.C water bath for 20min, taking out the ice bath for 5min, and measuring absorbance at 387 nm. And (3) calculating the concentration of cholate in the sample solution by a standard curve equation, subtracting the concentration from the concentration of the added cholate to obtain the concentration of the combined cholate, and calculating the content of the combined cholate in unit mass.

Fig. 3 shows the in vitro cholate binding capacity of the purified polysaccharide component P2 from the myrtle fruit, and the results show that the relative binding rates of myrtle polysaccharide P2 to sodium taurocholate, sodium glycocholate and sodium cholate are respectively, calculated by taking cholestyramine (a lipid-lowering drug, whose mechanism of lowering blood lipid is to bind cholate) as a positive control and taking the binding rate of cholestyramine to each cholate as 100%: 29.87%, 47.49% and 53.69%.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. The application of myrtle polysaccharide P2 in preparing the hypolipidemic drug is characterized in that:

(1) drying and crushing myrtle fruits, boiling and extracting dry powder and distilled water in a reflux device for several times, combining extracting solutions, concentrating under reduced pressure, adding 95% (V/V) ethanol with a volume being several times that of the concentrated solution, continuously stirring to enable polysaccharide to be uniformly precipitated, standing for more than 12 hours at 4 ℃, centrifugally collecting precipitates, and drying to obtain crude myrtle fruit polysaccharide;

(2) dissolving crude polysaccharide of Myrtus communis fruit in distilled water, adjusting pH to 8.0, and adding 30% H dropwise₂O₂Stirring the solution until the color of the solution becomes light, and then preserving the temperature for 2 hours in a water bath at 50 ℃;

(3) adding Sevag reagent with the volume of 1/5 into the decolorized polysaccharide solution, performing shaking culture for 20min, standing for 10min, centrifuging, discarding gel substances generated by lower organic phase and middle protein, chloroform and n-butanol, and repeating the centrifuging and discarding operations for several times; after the last operation, removing the residual Sevag reagent in the solution by rotary evaporation to obtain a deproteinized myrtle fruit polysaccharide solution, collecting precipitates according to the alcohol precipitation method in the step (1), and drying to obtain primarily purified myrtle fruit polysaccharide;

(4) pre-treating DEAE-sepharose gel filler, loading the filler into a column, dissolving the preliminarily purified myrtle fruit polysaccharide obtained in the step (3) by using deionized water, passing the solution through a 0.45-micrometer microporous filter membrane, and loading the solution into the column; eluting with distilled water, eluting per 0.1g of myrtle fruit polysaccharide with 150mL of distilled water, and collecting no fraction; then eluting with NaCl solution with the concentration of 0.1mol/L, collecting one tube of eluent every 5mL, detecting the absorbance value of the eluent at the detection wavelength of 490nm by using a phenol-sulfuric acid method, stopping collecting until the absorbance value is close to zero, merging fractions, concentrating, dialyzing, and freeze-drying to obtain polysaccharide P2;

the myrtle polysaccharide P2 comprises the following monosaccharides in mole percentage: 8.25% of ribose, 2.10% of rhamnose, 53.75% of arabinose, 5.16% of xylose, 8.22% of mannose, 12.01% of glucose and 10.51% of galactose;

the number average molecular weight of the myrtle polysaccharide P2 is 2.57 multiplied by 10⁴Da with a weight average molecular weight of 6.75X 10⁴Da。

2. Use according to claim 1, characterized in that: and (4) the flow rate of the sample loading and elution is 0.5 mL/min.

3. Use according to claim 1, characterized in that: the medicine contains acceptable auxiliary materials and other effective components which play a compatible and synergistic effect.

4. Use according to claim 1, characterized in that: the medicine can be tablet, granule, capsule, dripping pill, sustained release preparation, oral liquid, and injection.