Preparation method and clinical application of mulberry leaf extract for controlling sugar and body weight

Abstract

The invention discloses a preparation method and clinical application of a mulberry leaf extract for controlling sugar and body weight, and belongs to the technical field of mulberry leaf extracts.According to the preparation method, the mulberry leaf extract is obtained through water extraction, ultrasonic secondary extraction, step-by-step separation of a precipitating aid and final microfiltration, ultrafiltration, concentration and spray drying. Wherein the precipitating aid is a polyethylene glycol grafted polyethyleneimine compound. According to the distributed separation, firstly, under the low concentration, a precipitating aid can promote mulberry leaf protein precipitation through steric hindrance and hydrophobic interaction, under the high concentration, impurity molecules such as mulberry leaf polysaccharide and tannin in a mulberry leaf extracting solution can be attached and wrapped, finally, impurities are removed through centrifugal filtration, an extracting solution rich in mulberry leaf alkaloid is obtained, and through step-by-step separation, the content of the mulberry leaf alkaloid in the mulberry leaf extracting solution is increased. The mulberry leaf protein in the extracting solution can be better reserved, the extraction efficiency is improved, and the mulberry leaf extract rich in mulberry leaf protein and mulberry leaf alkaloid is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of mulberry leaf extract, and particularly relates to a preparation method of a mulberry leaf extract for controlling blood sugar and body weight and its clinical application. Background Art

[0002] With the changes in social structure, the acceleration of the pace of life, the changes in eating habits and food composition, and the aging of society, the human disease spectrum has undergone a great transformation. The incidence of chronic diseases related to dietary nutrition, such as diabetes, cardiovascular diseases, obesity, hyperlipidemia, etc., has been rising continuously, becoming a major global public health problem. As one of the chronic diseases most closely related to dietary nutrition, the scientific diet control of diabetes has received wide attention.

[0003] Mulberry leaf extract refers to the substances extracted from natural mulberry leaf raw materials, which are rich in various active ingredients and can help act on the human metabolism process and contribute to maintaining normal blood sugar levels. However, traditional mulberry leaf extraction processes often focus on the maximum extraction efficiency of a single component, ignoring the simultaneous acquisition of other important active ingredients and the synergistic effect between the overall components of mulberry leaves.

[0004] And in the current mulberry leaf extraction process, processing aids such as acids are mostly used, the process is complex, and the environmental pollution is large. Therefore, it is of great significance to obtain a mulberry leaf extract that simultaneously retains multiple mulberry leaf active ingredients and use it as a raw material to make a preparation product with the efficacy of controlling blood sugar and body weight. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a mulberry leaf extract for controlling blood sugar and body weight and its clinical application, so as to solve the problem of simultaneously improving the extraction efficiency of alkaloids and mulberry leaf proteins in the mulberry leaf extract.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] In the first aspect, the present invention provides a preparation method of a mulberry leaf extract for controlling blood sugar and body weight, including the following technological steps:

[0008] S1. The mulberry leaves are subjected to water extraction to obtain a mulberry leaf water extract and mulberry leaf residues;

[0009] S2. The mulberry leaf residues are dispersed in water, ultrasonically treated, the temperature is raised to 35 - 45 °C, heated for 30 - 50 min, and centrifuged to obtain a crude mulberry leaf protein extract;

[0010] S3. The mulberry leaf water extract and the crude mulberry leaf protein extract are mixed to obtain a crude mulberry leaf extract;

[0011] S4. A co-precipitant is added to the crude mulberry leaf extract, and a solid substance is separated;

[0012] S5. Continuously add a co-precipitant to the crude mulberry leaf extract, adjust the pH value of the solution to 5.5 - 6.5, and perform centrifugal separation to obtain the mulberry leaf extract;

[0013] S6. Dissolve the solid matter in the mulberry leaf extract, and obtain the mulberry leaf extract through microfiltration, ultrafiltration, concentration, and spray drying;

[0014] The co-precipitant is a polyethylene glycol grafted polyethyleneimine complex.

[0015] Preferably, in step S2, the material-liquid ratio of mulberry leaf residue to water is 1 g : (25 - 30) mL.

[0016] Preferably, microfiltration is carried out using a tubular separation device at a rotation speed of 10000 - 12000 r / min.

[0017] Preferably, ultrafiltration is carried out using a ceramic membrane separation device. The number of pores of the ceramic membrane separation device is 32 - 45, the separation precision is 90 - 105 nm, the pore diameter is 3.3 - 3.7 mm, and the membrane tube length is 0.85 - 1.25 m.

[0018] By adopting the above technical solution, the mulberry leaf raw material can effectively obtain various bioactive components from the mulberry leaves through water extraction. It not only retains the natural properties of the mulberry leaves but also effectively avoids the use of organic solvents. A large number of nutritional components in the mulberry leaves, such as flavonoids, polyphenols, alkaloids, etc., are dissolved from the mulberry leaves into the aqueous solution. Among them, alkaloids can inhibit α-glucosidase to prevent the further digestion and absorption of carbohydrates, thereby reducing the postprandial blood glucose peak, improving lipid metabolism, and enhancing the body's immunity.

[0019] On the one hand, mulberry leaf protein can assist alkaloids, and their interaction can help alkaloids play a better effect. On the other hand, it can also help improve the insulin signal transduction pathway, enhance the cell's response ability to insulin, and improve the body's efficiency in using glucose, thus achieving the effect of controlling blood sugar and body weight. However, due to the relatively large molecular size and complex structure of mulberry leaf protein, it is not easy to penetrate the cell wall and cell membrane, and simply using water extraction will limit their release from the mulberry leaf tissue. Therefore, after water extraction of the mulberry leaves, a large amount of mulberry leaf protein components remain undissolved in the mulberry leaf residue.

[0020] Performing ultrasonic treatment on the mulberry leaf residue can significantly increase the dissolution rate of proteins by destroying the cell wall, thus obtaining the crude mulberry leaf protein extract.

[0021] The obtained crude mulberry leaf extract also contains a large amount of impurities. First, a co-precipitant, namely polyethylene glycol grafted polyethyleneimine complex, is used for secondary separation. The first separation yields the solid matter of proteins. The second separation allows the co-precipitant to adsorb impurity components such as mulberry polysaccharides and tannins in the crude mulberry leaf extract, mainly retaining the active components including alkaloids. Next, the solid matter is dissolved in the separated extract, and finally, through a two-stage filtration process, the impurity components in the extract are further reduced to obtain a mulberry leaf extract rich in mulberry leaf protein and mulberry leaf alkaloids.

[0022] Preferably, in step S4, the mass fraction of the co-precipitant in the crude mulberry leaf extract is controlled to be 15-20%; in step S5, the mass fraction of the co-precipitant in the crude mulberry leaf extract is controlled to be 35-40%.

[0023] By adopting the above technical solution, during the separation assisted by the co-precipitant, first, the co-precipitant is controlled to be dispersed at a low concentration in the crude mulberry leaf extract. At this time, the co-precipitant molecules will form a network structure in the solution, exerting a spatial repulsion effect on the mulberry leaf protein molecules, causing the mulberry leaf protein molecules to aggregate and precipitate. Moreover, the polyethylene glycol grafted polyethyleneimine complex has hydrophilicity, which can reduce the hydration layer on the surface of protein molecules and promote the precipitation process. The low-concentration dispersion can also ensure that the mulberry leaf protein will not be overly aggregated or deformed due to the action of the grafted polyethyleneimine chain segments, thereby maintaining the biological activity of the mulberry leaf protein. The obtained solid matter is precipitated from the mulberry leaf protein.

[0024] Subsequently, the co-precipitant is continuously added to increase the mass fraction of the co-precipitant in the crude mulberry leaf extract, making the co-precipitant dispersed at a high concentration in the crude mulberry leaf extract. At this time, the high-molecular-weight polyethylene glycol grafted polyethyleneimine complex can form larger aggregates in the crude mulberry leaf extract. These aggregates will adsorb and encapsulate impurity molecules such as mulberry polysaccharides and tannins in the mulberry leaf extract. Finally, the impurities are removed by centrifugal filtration to obtain an extraction solution rich in mulberry leaf alkaloids. Through step-by-step separation, the mulberry leaf protein in the extract can be better retained, the extraction efficiency can be improved, and a mulberry leaf extract rich in both mulberry leaf protein and mulberry leaf alkaloids can be obtained.

[0025] Preferably, the raw materials of the polyethylene glycol grafted polyethyleneimine complex include polyethylene glycol and polyethyleneimine with a mass ratio of 1:(0.2-0.3).

[0026] Preferably, the molecular weight of the polyethylene glycol is 4000-6000 g / mol.

[0027] Preferably, the polyethylene glycol grafted polyethyleneimine complex is prepared according to the following method:

[0028] Polyethylene glycol was added to water and stirred until dissolved. The temperature was raised to 80 - 85 °C, and an epoxy group-containing silane coupling agent was added. After stirring and reacting for 2 - 3 h, a pre-reaction solution was obtained; polyethyleneimine was dissolved in water, mixed with the pre-reaction solution, and stirred and reacted for 15 - 20 h. Finally, a polyethylene glycol-grafted polyethyleneimine composite was obtained through drying and grinding.

[0029] Preferably, the addition amount of the epoxy group-containing silane coupling agent is 5 - 10% of the mass of polyethylene glycol.

[0030] Preferably, the epoxy group-containing silane coupling agent includes one or a combination of more of γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane.

[0031] The co-precipitant is highly dispersed in the crude mulberry leaf extract, which can help adsorb and encapsulate impurity molecules. However, at the same time, it will affect the small-molecule mulberry leaf alkaloids and combine with polyethylene glycol, thus affecting the extraction efficiency and content of mulberry leaf alkaloids.

[0032] By adopting the above technical scheme, through the action of the epoxy group-containing silane coupling agent, the polyethyleneimine chain segment is grafted onto the molecular chain of polyethylene glycol. Since the main components of mulberry leaf alkaloids include polyhydroxy alkaloids such as 1-deoxynojirimycin, they exhibit positive charge characteristics under acidic conditions, while impurity molecules such as mulberry leaf polysaccharides and tannins maintain negative charge characteristics under acidic conditions. By grafting polyethyleneimine onto the polyethylene glycol molecular chain, a large number of primary amines, secondary amines, and tertiary amines and other groups contained in polyethyleneimine can be protonated in aqueous solution to form positively charged ammonium ions, and thus it also has a certain branched structure, which can effectively increase the number of cationic sites on the polyethylene glycol molecular chain, increase the contact area with impurity molecules, and strengthen the electrostatic attraction with negatively charged macromolecular impurities, thereby improving the selective adsorption of the co-precipitant in the mulberry leaf extract.

[0033] The positively charged functional groups contained in polyethyleneimine can not only increase the number of cation exchange sites, but also increase the binding strength between the co-precipitant and impurity molecules through non-covalent interactions such as hydrogen bonds, so as to effectively separate impurity molecules from the crude mulberry leaf extract and improve the efficacy of the mulberry leaf extract in aspects such as blood sugar control and weight control.

[0034] Moreover, due to the fact that polyethyleneimine has a certain branched structure, it can, while effectively adsorbing macromolecular impurities, utilize steric hindrance to limit the approach and combination of small-molecule alkaloids, thereby increasing the effective content of mulberry leaf alkaloids in the mulberry leaf extract.

[0035] In a second aspect, the present invention provides a clinical application of a mulberry leaf extract for controlling blood sugar and body weight, which is prepared according to the above preparation method; the clinical application includes any one of controlling postprandial blood sugar levels, improving lipid metabolism, supporting intestinal health, and losing weight.

[0036] Advantages of the present invention:

[0037] 1. In the preparation method of the mulberry leaf extract for controlling blood sugar and body weight of the present invention, a co-precipitant is used to separate the crude mulberry leaf extract, and the co-precipitant is a polyethylene glycol grafted polyethyleneimine complex. Polyethyleneimine provides a large number of cation exchange sites for polyethylene glycol, which can form strong electrostatic attraction with impurity molecules such as mulberry polysaccharides and tannins, improving the selective adsorption ability of the co-precipitant for impurity molecules. Moreover, its branched structure can also use the steric hindrance effect to limit the approach and binding of small molecule alkaloids, increasing the content of mulberry alkaloids in the obtained mulberry leaf extract.

[0038] 2. In the preparation method of the mulberry leaf extract for controlling blood sugar and body weight of the present invention, the co-precipitant is added twice to control its concentration in the crude mulberry leaf extract, thereby separating the active ingredients in the crude mulberry leaf extract step by step. Specifically, under low concentration conditions, the co-precipitant can promote the precipitation of mulberry leaf proteins through steric hindrance and hydrophobic effects to form solids, avoiding the influence of subsequent treatment processes; under high concentration conditions, the high molecular weight co-precipitant can attach to and wrap impurity molecules such as mulberry polysaccharides and tannins in the mulberry leaf extract, and finally the impurities are removed by centrifugal filtration to obtain an extraction solution rich in mulberry alkaloids. By separating step by step, the mulberry leaf proteins in the extraction solution can be better retained, improving the extraction efficiency, and obtaining a mulberry leaf extract rich in both mulberry leaf proteins and mulberry alkaloids. Specific embodiments

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0040] Preparation examples

[0041] Preparation Example 1, a co-precipitant, is prepared according to the following method:

[0042] Take 10 g of polyethylene glycol (average molecular weight: 6000 g / mol) and add it to water, stir to dissolve, raise the temperature to 80 °C, add 0.8 g of γ-glycidoxypropyltrimethoxysilane, stir and react for 3 h to obtain a pre-reaction solution; take 2.5 g of polyethyleneimine (average molecular weight: 600 g / mol) and dissolve it in water, mix it with the pre-reaction solution, stir and react for 20 h, and finally obtain a polyethylene glycol-grafted polyethyleneimine composite through drying and grinding.

[0043] Preparation Example 2, a co-precipitant, which is only different from Preparation Example 1 in that the addition amount of polyethyleneimine is 2 g.

[0044] Preparation Example 3, a co-precipitant, which is only different from Preparation Example 1 in that the addition amount of polyethyleneimine is 3 g.

[0045] Preparation Example 4, a co-precipitant, which is only different from Preparation Example 1 in that the addition amount of polyethyleneimine is 1 g.

[0046] Preparation Example 5, a co-precipitant, which is only different from Preparation Example 1 in that the addition amount of polyethyleneimine is 4 g.

[0047] Example

[0048] Example 1, a mulberry leaf extract for controlling blood sugar and body weight, is prepared according to the following process steps:

[0049] S1. The mulberry leaves are subjected to water extraction, in which water extraction is carried out 2 times, the material-liquid ratio is 1 g: 20 mL, reflux extraction is carried out at 90 °C for 2 h, and after coarse screening through a 100-mesh filter screen, a mulberry leaf water extract and mulberry leaf residues are obtained;

[0050] S2. The mulberry leaf residues are dispersed in water, the material-liquid ratio is controlled to be 1 g: 30 mL, ultrasonic treatment is carried out for 15 min, the temperature is raised to 40 °C, heating is carried out for 40 min, and centrifugation is carried out to obtain a crude mulberry leaf protein extract;

[0051] S3. The mulberry leaf water extract and the crude mulberry leaf protein extract are mixed to obtain a crude mulberry leaf extract;

[0052] S4. Add the co-precipitant prepared in Preparation Example 1 to the crude mulberry leaf extract, control the mass fraction of the co-precipitant in the crude mulberry leaf extract to be 15%, stir and mix, and separate to obtain a solid;

[0053] S5. Continue to add the co-precipitant prepared in Preparation Example 1 to the crude mulberry leaf extract, control the mass fraction of the co-precipitant in the crude mulberry leaf extract to be 35%, adjust the pH value of the solution to 6, and carry out centrifugal separation to obtain a mulberry leaf extract;

[0054] S6. Dissolve the solid matter in the mulberry leaf extract, and perform microfiltration (rotation speed is 12,000 r / min) through a tubular separation device, ultrafiltration (the number of holes in the device is 37, the separation accuracy is 100 nm, the pore diameter is 3.5 mm, and the membrane tube length is 1 m) through a ceramic membrane separation device, concentration, and spray drying to obtain the mulberry leaf extract.

[0055] Example 2. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that the precipitant obtained in Preparation Example 2 is used to replace the precipitant obtained in Preparation Example 1 in equal amount.

[0056] Example 3. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that the precipitant obtained in Preparation Example 3 is used to replace the precipitant obtained in Preparation Example 1 in equal amount.

[0057] Example 4. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that in step S4, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 20%; in step S5, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 40%.

[0058] Example 5. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that in step S4, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 35%.

[0059] Example 6. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that in step S5, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 20%.

[0060] Example 7. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that in step S4, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 10%.

[0061] Example 8. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that in step S5, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 50%.

[0062] Example 9. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that the precipitant obtained in Preparation Example 4 is used to replace the precipitant obtained in Preparation Example 1 in equal amount.

[0063] Example 10. A mulberry leaf extract for blood sugar control and weight management, which is different from Example 1 only in that the precipitant obtained in Preparation Example 5 is used to replace the precipitant obtained in Preparation Example 1 in equal amount.

[0064] Comparative Example

[0065] Comparative Example 1, a mulberry leaf extract for blood sugar and body weight control, is different from Example 1 only in that an equal amount of polyethylene glycol (average molecular weight: 6000 g / mol) is used to replace the co-precipitant prepared in Preparation Example 1.

[0066] Comparative Example 2, a mulberry leaf extract for blood sugar and body weight control, is different from Example 1 only in that step S5 is adjusted, specifically: the pH value of the crude mulberry leaf extract after separating the solid matter is adjusted to 6, and then centrifuged to obtain the mulberry leaf extract.

[0067] Comparative Example 3, a mulberry leaf extract for blood sugar and body weight control, is prepared according to the following process steps:

[0068] S1. The mulberry leaves are extracted with water. Specifically, water extraction is carried out twice, the solid-liquid ratio is 1 g: 20 mL, reflux extraction is carried out at 90 °C for 2 h, and then coarse screening is carried out through a 100-mesh filter to obtain the mulberry leaf water extract and mulberry leaf residue;

[0069] S2. The mulberry leaf residue is dispersed in water, the solid-liquid ratio is controlled to be 1 g: 30 mL, ultrasonic treatment is carried out for 15 min, the temperature is raised to 40 °C, heating is carried out for 40 min, and then centrifuged to obtain the crude mulberry leaf protein extract;

[0070] S3. The mulberry leaf water extract and the crude mulberry leaf protein extract are mixed to obtain the crude mulberry leaf extract;

[0071] S4. The co-precipitant prepared in Preparation Example 1 is added to the crude mulberry leaf extract, the mass fraction of the co-precipitant in the crude mulberry leaf extract is controlled to be 15%, the pH value of the solution is adjusted to 6, and then centrifuged to obtain the mulberry leaf extract;

[0072] S5. The mulberry leaf extract is subjected to microfiltration (rotation speed: 12000 r / min) through a tubular separation device, ultrafiltration (number of pores of the device: 37, separation accuracy: 100 nm, pore diameter: 3.5 mm, membrane tube length: 1 m) through a ceramic membrane separation device, concentration and spray drying to obtain the mulberry leaf extract.

[0073] Comparative Example 4, a mulberry leaf extract for blood sugar and body weight control, is prepared according to the following process steps:

[0074] S1. The mulberry leaves are extracted with water. Specifically, water extraction is carried out twice, the solid-liquid ratio is 1 g: 20 mL, reflux extraction is carried out at 90 °C for 2 h, and then coarse screening is carried out through a 100-mesh filter to obtain the mulberry leaf water extract and mulberry leaf residue;

[0075] S2. The co-precipitant prepared in Preparation Example 1 is added to the mulberry leaf water extract, the mass fraction of the co-precipitant in the crude mulberry leaf extract is controlled to be 15%, stirred and mixed, and then the solid matter is separated;

[0076] S3. Continuously add the co-precipitant prepared in Preparation Example 1 to the aqueous extract of mulberry leaves, control the mass fraction of the co-precipitant in the crude mulberry leaf extract to be 35%, adjust the pH value of the solution to 6, and perform centrifugal separation to obtain the mulberry leaf extract;

[0077] S4. Dissolve the solid matter in the mulberry leaf extract, and perform microfiltration (rotation speed: 12,000 r / min) through a tubular separation device, ultrafiltration (number of pores of the device: 37, separation precision: 100 nm, pore diameter: 3.5 mm, membrane tube length: 1 m) through a ceramic membrane separation device, concentration, and spray drying to obtain the mulberry leaf extract.

[0078] Comparative Example 5, a mulberry leaf extract for controlling blood sugar and body weight, is prepared according to the following process steps:

[0079] S1. Extract mulberry leaves with water, wherein water extraction is performed 2 times, the material-liquid ratio is 1 g: 20 mL, reflux extraction is performed at 90 °C for 2 h, and coarse screening is performed through a 100-mesh sieve to obtain the aqueous extract of mulberry leaves and mulberry leaf residues;

[0080] S2. Disperse the mulberry leaf residues in water, control the material-liquid ratio to be 1 g: 30 mL, perform ultrasonic treatment for 15 min, raise the temperature to 40 °C, heat for 40 min, and perform centrifugation to obtain the crude extract of mulberry leaf protein;

[0081] S3. Mix the aqueous extract of mulberry leaves and the crude extract of mulberry leaf protein to obtain the crude mulberry leaf extract;

[0082] S4. The crude mulberry leaf extract is subjected to microfiltration (rotation speed: 12,000 r / min) through a tubular separation device, ultrafiltration (number of pores of the device: 37, separation precision: 100 nm, pore diameter: 3.5 mm, membrane tube length: 1 m) through a ceramic membrane separation device, concentration, and spray drying to obtain the mulberry leaf extract.

[0083] Performance detection test

[0084] Select 13 healthy adults aged 18 - 40 years old, without metabolic diseases, digestive diseases, and endocrine diseases, without a history of diabetes, and not using hypoglycemic drugs for clinical testing.

[0085] Test arrangement: Three days before the test, the subjects should have regular work and rest and normal diet. On the day before the test, avoid high-fiber and high-sugar foods for dinner, do not drink alcohol, start eating before 22:00, and avoid strenuous exercise on the morning of the measurement day.

[0086] After the subjects arrived at the test site, they sat quietly for 10 minutes and then began the food intake test. The test foods were rice and mulberry leaf extract. The dosage of mulberry leaf extract was 0.7 g, and the dosage of rice was 66.7 g. During the food intake test, fasting blood samples were collected every 5 minutes. After the collection was completed, the subjects began to eat. All the test foods and a 250 mL glass of water were eaten within 5 - 12 minutes. Timing started from the time of the first bite. Blood samples were collected at 15, 30, 45, 60, 90, and 120 minutes after the meal respectively.

[0087] The measurement period included one control test (only eating rice) and the combinations of mulberry leaf extract and rice obtained in the examples and comparative examples, totaling 15 times. A randomized design was adopted, and the interval between each independent food intake measurement was ≥ 72 h.

[0088] The blood glucose and insulin changes in the test blood samples were measured. The average change value of each independent food intake was taken to obtain the peak values of blood glucose and insulin after the meal. The test results are shown in Table 1:

[0089] Table 1 Test Results of Performance Detection

[0090]

[0091] According to Table 1, in combination with Example 1 and Examples 5 - 8, it can be seen that the peak blood glucose and peak insulin in Examples 5 - 8 are both increased compared with Example 1, indicating that the ability of the mulberry leaf extracts obtained in Examples 5 - 8 to reduce blood glucose and absorb blood glucose has decreased. The reason is that during the preparation of the mulberry leaf extracts in Examples 5 - 8, the concentrations of the two additions of the co - precipitant were adjusted. When the first concentration increased or decreased, the extraction effect of mulberry leaf protein decreased. When the concentration increased, it was difficult to have a steric repulsion effect with the macromolecular mulberry leaf protein, thus leading to the aggregation and deposition of mulberry leaf protein. When the second concentration increased or decreased, the extraction effect of mulberry leaf alkaloids decreased. When the concentration increased, the mulberry leaf alkaloids would also react with the co - precipitant, resulting in a decrease in the final concentration of the obtained mulberry leaf alkaloids. When the concentration decreased, the impurity substances in the mulberry leaf extract were difficult to be adsorbed and removed, affecting the blood glucose control effect of the mulberry leaf extract.

[0092] Combined with Example 1, Example 9, Example 10 and Comparative Example 1, it can be seen that the blood glucose peak and insulin peak of Example 9, Example 10 and Comparative Example 1 are all increased compared with Example 1. The reason is that the grafting rate of polyethyleneimine grafted on polyethylene glycol in the co-precipitant is adjusted. Among them, in Example 9, the polyethyleneimine chain segment on the polyethylene glycol molecular chain is reduced, which will reduce the selective adsorption of the co-precipitant to impurity molecules, and will also cause some mulberry leaf alkaloids to be adsorbed and removed by the co-precipitant, resulting in a decrease in the blood glucose control effect of the finally obtained mulberry leaf extract. In Comparative Example 1, polyethylene glycol was not modified with polyethyleneimine, and the performance degradation was more obvious. In Example 10, the grafting rate of the polyethyleneimine chain segment was increased, which would reduce the attraction between polyethylene glycol itself and macromolecular impurity molecules, resulting in a decrease in the impurity removal rate.

[0093] Combined with Example 1 and Comparative Examples 2 to 5, it can be seen that the blood glucose peak and insulin peak of Comparative Examples 2 to 5 are all increased compared with Example 1. The reason is that in Comparative Example 2, the concentration of the second co-precipitant was not changed, resulting in a significant decrease in the separation effect of small molecule alkaloids and impurity molecules. In Comparative Example 3, the separation was not carried out step by step in two parts, which would lead to a decrease in the content of mulberry leaf protein and an increase in the content of impurity molecules in the finally obtained mulberry leaf extract. In Comparative Example 4, without pre-ultrasonic treatment, it is difficult for the mulberry leaf protein in the mulberry leaf to be completely dissolved by the water extraction method, resulting in a decrease in the content of mulberry leaf protein in the mulberry leaf extract. In Comparative Example 5, no co-precipitant was added, resulting in a decrease in the extraction effect of mulberry leaf protein and the separation effect of impurity molecules, leading to a decrease in the blood glucose control effect of the mulberry leaf extract.

[0094] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variation thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0095] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a mulberry leaf extract for controlling sugar and weight, characterized in that: The process steps include: S1. extracting mulberry leaves with water to obtain mulberry leaf water extract and mulberry leaf residue; S2. dispersing the mulberry leaf residue in water, ultrasonically treating it, raising the temperature to 35-45°C, heating it for 30-50 minutes, and centrifuging it to obtain a crude extract of mulberry leaf protein; S3. Mixing the mulberry leaf aqueous extract and the mulberry leaf protein crude extract to obtain a mulberry leaf crude extract; S4. adding a precipitating agent to the crude mulberry leaf extract to separate the solids; S5. Continue to add the precipitant to the crude mulberry leaf extract, adjust the pH value of the solution to 5.5-6.5, and centrifuge to obtain a mulberry leaf extract; S6. dissolving the solid in the mulberry leaf extract, and obtaining the mulberry leaf extract by microfiltration, ultrafiltration, concentration and spray drying; The precipitation aid is a polyethylene glycol grafted polyethylene imine complex.

2. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 1, characterized in that: In the step S4, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 15-20%; in the step S5, the mass fraction of the precipitant in the crude mulberry leaf extract is controlled to be 35-40%.

3. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 1, characterized in that: The raw materials of the polyethylene glycol-grafted polyethylene imine composite include polyethylene glycol and polyethylene imine in a mass ratio of 1: (0.2-0.3).

4. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 3, characterized in that: The molecular weight of the polyethylene glycol is 4000-6000 g / mol.

5. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 3, characterized in that: The polyethylene glycol grafted polyethyleneimine composite is prepared according to the following method: Add polyethylene glycol to water and stir to dissolve, raise the temperature to 80-85°C, add epoxy silane coupling agent, stir to react for 2-3 hours to obtain a pre-reaction solution; dissolve polyethylene imine in water, mix with the pre-reaction solution, stir to react for 15-20 hours, and finally dry and grind to obtain a polyethylene glycol-grafted polyethylene imine composite.

6. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 5, characterized in that: The added amount of the epoxy silane coupling agent is 5-10% of the mass of the polyethylene glycol.

7. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 1, characterized in that: In the step S2, the material-liquid ratio of mulberry leaf residue to water is 1 g: (25-30) mL.

8. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 1, characterized in that: The microfiltration utilizes tubular separation equipment for filtration at a rotation speed of 10,000 to 12,000 r / min.

9. The method for preparing the mulberry leaf extract for controlling sugar and weight according to claim 1, characterized in that: The ultrafiltration utilizes a ceramic membrane separation device for filtration, the ceramic membrane separation device has 32 to 45 pores, a separation accuracy of 90 to 105 nm, a pore size of 3.3 to 3.7 mm, and a membrane tube length of 0.85 to 1.25 m.

10. A clinical application of mulberry leaf extract for controlling sugar and weight, characterized in that: The mulberry leaf extract is prepared according to the preparation method of the mulberry leaf extract for controlling sugar and weight described in any one of Preparation Examples 1 to 9; the clinical application includes any one of controlling postprandial blood sugar levels, improving lipid metabolism, supporting intestinal health and losing weight.

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