A preparation method of Momordica grosvenori leaf extract

Abstract

The present invention discloses a method for preparing a Momordica grosvenori leaf extract, which relates to the field of plant extraction technology. The method comprises the following steps: extracting the Momordica grosvenori leaf raw material using an ethanol-water solution, concentrating the extract, separating the extract using a macroporous resin, and collecting the alcohol eluate; converting the alcohol eluate into an aqueous phase, passing the aqueous phase through a polar macroporous resin column, performing gradient elution, and collecting the alcohol eluates; and treating the alcohol eluates separately to obtain a mogroflavin extract and a kaempferol extract. The method of the present invention can produce a kaempferol extract with a purity greater than 90% and a mogroflavin extract with a purity greater than 70% using only a resin column and crystallization method, with a recovery rate of greater than 80%, making the method suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of plant extraction, and in particular relates to a method for preparing a Momordica grosvenori leaf extract. Background Art

[0002] Momordica grosvenorii (Swingle) C. Jeffrey ex Lu et Z.Y. Zhang] is a perennial vine of the Cucurbitaceae family (Cucurbitaceae), and is an economic and medicinal plant unique to my country.

[0003] The main active ingredients in Momordica grosvenori fruit are mogrosides, among which mogroside (mogroside V as the main component) has a higher economic value; Momordica grosvenori roots are rich in demethylcucurbitane compounds, and Momordica grosvenori leaves are rich in flavonoids, mainly flavonoid glycosides with kaempferol and quercetin as the aglycones, among which kaempferol and mogroflavin are at higher levels.

[0004] Kaempferol, also known as kaempferol-3,7-OL-dirhamnoside, has pharmacological activities such as lowering blood sugar, lowering blood pressure, clearing away heat and detoxifying. It is mainly found in the dried roots of Bupleurum chinense of the Apiaceae family; Momordica grosvenori (CAS number 156980-60-8, 7-O-α-L-rhamnose-7-O-[β-D-glucosyl-(1-2)-α-L-rhamnoside) is found in Momordica grosvenori.

[0005] CN105732743A discloses a method for extracting and preparing high-purity kaempferol from burmanii cinnamomea leaves. The method is achieved by water extraction, water extraction and alcohol precipitation, alcohol-ether precipitation, and crystallization and recrystallization. The kaempferol prepared by this method has high purity; however, the use of ether as a harmful solvent limits industrial production.

[0006] CN107098942A discloses a method for preparing kaempferol from radish leaves. The method uses subcritical water extraction and leaching, followed by separation with a macroporous resin and subsequent crystallization and recrystallization. The subcritical state has a high pressure, which can easily pose a safety hazard.

[0007] CN102875619A discloses a method for extracting kaempferol from purple-leaf plum leaves. The method comprises extracting the purple-leaf plum leaves with an ethanol aqueous solution and concentrating under reduced pressure. The concentrate is allowed to stand for 12 to 24 hours and then centrifuged. The centrifuged solution is diluted and then applied to a macroporous resin column for gradient elution. The effective fraction is placed at a temperature of -6 to 5°C for 6 to 8 days for crystallization. After crystallization, the effective fraction is filtered to obtain a crude crystal product and a mother liquor. The crude crystal product is washed with water and dried under vacuum at room temperature to obtain the kaempferol product. This method takes a long time for crystallization, resulting in a long process time, which is not conducive to industrial large-scale production.

[0008] CN107698638A discloses a method for extracting kaempferol from the stems and leaves of Momordica grosvenori. The method discloses the use of ethanol and ultrasonic extraction of kaempferol, but does not purify the component.

[0009] CN109021046A discloses a method for simultaneously extracting quercetin and kaempferol from the stems and leaves of Momordica grosvenori. The method adopts countercurrent flash extraction, ultrafiltration of the filtrate on a macroporous resin, and separation using preparative liquid chromatography after alcohol precipitation to remove impurities. This method is relatively costly and not suitable for industrial production.

[0010] CN102977165A discloses a method for purifying and preparing momordica grosvenori flavescent pigment, which uses mature momordica grosvenori fruit as raw material, decocts the pigment in water, performs preliminary separation with a macroporous resin, and then uses a gel chromatography column twice to obtain momordica grosvenori flavescent pigment with a purity greater than 95%.

[0011] Moreover, related technologies often use Momordica grosvenori fruit as the main raw material during the production process, while the above-ground part is usually discarded, resulting in a waste of resources.

[0012] Therefore, the present invention provides a method for preparing a Momordica grosvenori leaf extract to solve at least one aspect of the problems and defects raised in the above background technology. Summary of the Invention

[0013] The object of the present invention is to provide a method for preparing a Momordica grosvenori leaf extract to solve at least one aspect of the problems and defects raised in the above background technology.

[0014] Specifically, the present invention discloses a method for preparing a Momordica grosvenori leaf extract, comprising the following steps:

[0015] S1. Extracting the Momordica grosvenori leaf raw material with an ethanol-water solution to prepare an extract;

[0016] The extract is concentrated, water is added, and the extract is filtered to obtain a first aqueous phase;

[0017] S2, passing the first aqueous phase through a macroporous resin column, eluting with water and an ethanol aqueous solution with a volume fraction of 40% to 60%, and collecting the ethanol eluate;

[0018] The ethanol eluate is concentrated and then water is added to prepare a diluent;

[0019] S3, passing the dilution solution through a polar macroporous resin column, sequentially using water, an ethanol aqueous solution with a volume fraction of 10% to 20%, and an ethanol aqueous solution with a volume fraction of 30% to 40%;

[0020] collecting an ethanol aqueous solution eluate with a volume fraction of 10% to 20% to obtain a Momordica grosvenori eluate;

[0021] collecting an ethanol aqueous solution eluate with a volume fraction of 30% to 40% to prepare a kaempferol eluate;

[0022] S4, concentrating the Momordica grosvenori eluate, adding water, and filtering to obtain a second aqueous phase;

[0023] Passing the second aqueous phase through a polyamide resin column, eluting with water and an ethanol aqueous solution with a volume fraction of 40% to 60%, collecting the ethanol eluate; concentrating the ethanol eluate and then drying it to obtain a Momordica grosvenori extract;

[0024] S5, concentrating the kaempferol eluate and adding 85% to 95% ethanol aqueous solution to obtain crude kaempferol;

[0025] The crude kaempferol is recrystallized to prepare a kaempferol extract.

[0026] According to one technical solution of the preparation method of the present invention, at least the following beneficial effects are achieved:

[0027] The present invention provides for the first time a method for simultaneously preparing kaempferol and mogroflavin from Momordica grosvenori leaves, which is conducive to better utilization of Momordica grosvenori leaves that may be discarded.

[0028] The present invention uses a macroporous resin as a separation medium. After separation by combining the resin with a crystallization method, a kaempferol product with a purity greater than 90% and a mogroflavin product with a purity greater than 70% can be obtained, and the recovery rates of both products are higher than 80%. The process is simple, no toxic organic reagents are used throughout the process, and industrial production is easy.

[0029] In the present invention, water is selected to elute impurities with greater polarity, and the volume fraction of the ethanol aqueous solution is controlled, thereby achieving product purification.

[0030] According to some embodiments of the present invention, the mesh size of the Momordica grosvenori leaf raw material is 50 mesh to 100 mesh.

[0031] According to some embodiments of the present invention, the extraction temperature in step S1 is 50°C to 65°C.

[0032] According to some embodiments of the present invention, the extraction method in step S1 is one of reflux extraction and continuous countercurrent extraction.

[0033] According to some embodiments of the present invention, the number of extractions in step S1 is 1 to 3 times.

[0034] According to some embodiments of the present invention, the extraction time in step S1 is 2 hours to 5 hours.

[0035] According to some embodiments of the present invention, in step S1, the mass volume ratio of the Momordica grosvenori leaf raw material to the ethanol aqueous solution with a volume fraction of 40% to 60% is 1 g: 4 to 10 mL.

[0036] According to some embodiments of the present invention, an ethanol aqueous solution with a volume fraction of 50% is selected during the extraction process.

[0037] According to some embodiments of the present invention, the mass concentration of the first liquid phase is 0.3 g / mL to 0.6 g / mL.

[0038] According to some embodiments of the present invention, the mass concentration of the first liquid phase is 0.5 g / mL.

[0039] According to some embodiments of the present invention, the filtration in step S1 uses a ceramic membrane;

[0040] The molecular weight cut-off of the ceramic membrane is 50 kDa to 100 kDa.

[0041] According to some embodiments of the present invention, the macroporous resin column in step S2 is one of a DM130 macroporous resin column, an AB-8 macroporous resin column, a DM-301 macroporous resin column and an HJ-14 macroporous resin column.

[0042] According to some embodiments of the present invention, in step S2, the column flow rate of the first aqueous phase is 2 BV / h to 3 BV / h.

[0043] According to some embodiments of the present invention, the loading volume of the first aqueous phase in step S2 is 3BV to 6BV.

[0044] According to some embodiments of the present invention, the amount of water used in step S2 is 2BV to 4BV.

[0045] According to some embodiments of the present invention, the flow rate of the water in step S2 is 3 BV / h to 6 BV / h.

[0046] According to some embodiments of the present invention, the amount of the ethanol aqueous solution with a volume fraction of 40% to 60% in step S2 is 2BV to 4BV.

[0047] According to some embodiments of the present invention, the flow rate of the ethanol aqueous solution with a volume fraction of 40% to 60% in step S2 is 1 BV / h to 3 BV / h.

[0048] According to some embodiments of the present invention, the content of kaempferol in the diluent is 5 mg / mL to 10 mg / mL.

[0049] According to some embodiments of the present invention, the polar macroporous resin column in step S3 is one of an ADS-7 macroporous resin column, a DA-201 macroporous resin column and an XAD-9 macroporous resin column.

[0050] According to some embodiments of the present invention, the column loading flow rate of the diluent in step S3 is 2 BV / h to 3 BV / h.

[0051] According to some embodiments of the present invention, the loading volume of the diluent in step S3 is 3BV to 6BV.

[0052] According to some embodiments of the present invention, the amount of water used in step S3 is 2BV to 4BV.

[0053] According to some embodiments of the present invention, the flow rate of the water in step S3 is 3 BV / h to 6 BV / h.

[0054] According to some embodiments of the present invention, the amount of the ethanol aqueous solution with a volume fraction of 10% to 20% in step S3 is 2BV to 4BV.

[0055] According to some embodiments of the present invention, the flow rate of the ethanol aqueous solution with a volume fraction of 10% to 20% in step S3 is 1 BV / h to 3 BV / h.

[0056] According to some embodiments of the present invention, the amount of the ethanol aqueous solution with a volume fraction of 30% to 40% in step S3 is 2BV to 4BV.

[0057] According to some embodiments of the present invention, the flow rate of the ethanol aqueous solution with a volume fraction of 30% to 40% in step S3 is 1 BV / h to 3 BV / h.

[0058] According to some embodiments of the present invention, a ceramic membrane is used for filtration in step S4; and the molecular weight cut-off of the ceramic membrane is 20 kDa to 50 kDa.

[0059] According to some embodiments of the present invention, the drying in step S4 is spray drying or vacuum drying.

[0060] According to some embodiments of the present invention, the crystallization temperature in step S5 is 4°C to 10°C.

[0061] According to some embodiments of the present invention, the crystallization time in step S5 is 6 hours to 12 hours.

[0062] According to some embodiments of the present invention, the number of recrystallization in step S5 is 1 to 2 times.

[0063] According to some embodiments of the present invention, the recrystallization temperature in step S5 is 4°C to 10°C.

[0064] According to some embodiments of the present invention, the solvent selected for the recrystallization in step S5 is an ethanol aqueous solution with a volume fraction of 85% to 95%.

[0065] According to some embodiments of the present invention, the recrystallization process in step S5 is as follows:

[0066] The crude kaempferol is mixed with an ethanol aqueous solution with a volume fraction of 85% to 95%, heated to dissolve, and cooled to crystallize.

[0067] According to some embodiments of the present invention, the mass volume ratio of the crude kaempferol to the ethanol aqueous solution with a volume fraction of 85% to 95% is 1 g: 15 mL to 20 mL.

[0068] According to some embodiments of the present invention, the temperature for heating and dissolving is 50°C-60°C.

[0069] According to some embodiments of the present invention, the temperature of the temperature-drop crystallization is 4°C to 10°C.

[0070] According to some embodiments of the present invention, the cooling crystallization time is 6 hours to 12 hours.

[0071] According to some embodiments of the present invention, the purity of the mogroflavin extract is 70% to 80%.

[0072] According to some embodiments of the present invention, the purity of the kaempferol extract is 90% to 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0074] Figure 1 This is the liquid chromatography test result of the Momordica grosvenori leaf raw material of the present invention. DETAILED DESCRIPTION

[0075] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0076] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0077] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0078] The preparation method of the Momordica grosvenori leaf raw material in the embodiment of the present invention is as follows:

[0079] Fresh Momordica grosvenori leaves were picked and kept at 100°C for 20 minutes to remove green leaves, and then dried at 60°C to constant weight to obtain dried Momordica grosvenori leaves;

[0080] The dried Momordica grosvenori leaves were crushed and passed through a 100-mesh sieve to obtain the Momordica grosvenori leaf raw material.

[0081] The method for detecting the content of kaempferol and mogroflavin in the Momordica grosvenori leaf raw material and extract in the embodiment of the present invention is as follows:

[0082] The Momordica grosvenori leaf raw material was ultrasonically extracted with methanol for 30 minutes to obtain a filtrate; the filtrate was passed through a 0.22 μm filter membrane (liquid organic phase filter membrane), and the subsequent filtrate was collected for liquid chromatography detection.

[0083] Liquid phase detection conditions are:

[0084] The chromatographic column is C18 (150 mm*4.6 mm, 5 μm);

[0085] Column temperature 30°C;

[0086] Detection wavelength 345nm;

[0087] Mobile phase: Phase A is acetonitrile, phase B is 0.4% phosphoric acid aqueous solution;

[0088] Gradient elution:

[0089] 0min~5min: the volume fraction of phase A is 15%~18%;

[0090] 5min~20min: the volume fraction of phase A is 18%~20%;

[0091] 20min~25min: The volume fraction of phase A is 20%~25%.

[0092] Under the above conditions, 3 batches of Momordica grosvenori leaf raw materials were tested, and the mass content of kaempferol was 3.1% (average value of three times), and the mass content of mogroflavin was 0.4% (average value of three times); the chromatogram is shown in FIG. Figure 1 (The retention time of mogroflavin is 16.05 min, and the retention time of kaempferol is 21.56 min).

[0093] Example 1

[0094] This embodiment is a preparation method of Momordica grosvenori leaf extract, which consists of the following steps:

[0095] S1. 500 g of Momordica grosvenori leaf raw material was mixed with 40% ethanol aqueous solution by volume and refluxed for 3 times to obtain an extract (the extracts were combined each time);

[0096] The temperature of the first reflux extraction was 50°C, the mass volume ratio of Momordica grosvenori leaf raw material and ethanol aqueous solution was 1 g:8 mL, and the extraction time was 1 h;

[0097] The temperature of the second reflux extraction was 50°C, the mass volume ratio of Momordica grosvenori leaf raw material and ethanol aqueous solution was 1 g:6 mL, and the extraction time was 1 h;

[0098] The temperature of the third reflux extraction was 50°C, the mass volume ratio of Momordica grosvenori leaf raw material and ethanol aqueous solution was 1 g:4 mL, and the extraction time was 1 h;

[0099] The extract was concentrated under reduced pressure to 1 / 10 of its original volume and diluted with water to prepare a first aqueous phase (concentration 0.3 g / mL (amount of raw material / solution));

[0100] The first aqueous phase was passed through a ceramic membrane with a molecular weight cut-off of 50 kDa, and the filtrate was collected.

[0101] S2. The filtrate obtained in step S1 was passed through HJ-14 macroporous adsorption resin. After adsorption, water and 40% by volume aqueous ethanol were used for elution, respectively. The aqueous ethanol eluate was collected, concentrated to remove ethanol, and then diluted with water to obtain a dilution solution (containing kaempferol content of 5 mg / mL).

[0102] S3, passing the diluted solution obtained in step S2 through an ADS-7 polar macroporous resin column. After loading, the solution is eluted with water, 10% by volume ethanol aqueous solution, and 30% by volume ethanol aqueous solution in sequence;

[0103] collecting the 10% volume fraction ethanol aqueous solution eluate to obtain the Momordica grosvenori extract;

[0104] collecting the 30% ethanol aqueous solution eluate to prepare the kaempferol extract;

[0105] The mogroflavin extract was concentrated and then water was added to prepare a dilution solution (the content of mogroflavin was 8 mg / mL);

[0106] S4. After the dilution in step S3 is passed through a ceramic membrane with a molecular weight cutoff of 30 kDa, the filtrate is passed through a polyamide column. After the column is loaded, water and a 40% ethanol aqueous solution are used for elution in sequence. The ethanol eluate is collected, concentrated and dried to obtain the Momordica grosvenori extract (light yellow powder).

[0107] S5, concentrating the kaempferol extract in step S3 to 20% of its original volume, and then adding 95% ethanol until the volume fraction of ethanol in the solution is 85%; heating to dissolve, filtering while hot, taking the filtrate and cooling it at 4°C for crystallization, standing it for 6 hours, and collecting the first crystals by solid-liquid separation;

[0108] The first crystals were mixed with an 85% ethanol aqueous solution (the weight-to-volume ratio of the first crystals to the 85% ethanol aqueous solution was 1 g:15 mL), heated to dissolve (50°C), filtered while hot, and the filtrate was cooled at 4°C for crystallization. After standing for 6 hours, the second crystals were collected by solid-liquid separation;

[0109] The second crystals were mixed with an 85% ethanol aqueous solution (the weight-to-volume ratio of the second crystals to the 85% ethanol aqueous solution was 1 g:15 mL), heated to dissolve (50°C), filtered while hot, and the filtrate was cooled at 4°C for crystallization. After standing for 6 hours, the third crystals were collected by solid-liquid separation and dried to obtain a kaempferol extract (off-white crystals).

[0110] The color of the Momordica grosvenori extract in this embodiment is light yellow, the mass is 2.38g, the mass purity is 72.35%, and the recovery rate is 86.59%;

[0111] The kaempferol extract in this example is off-white in color, weighs 14.38 g, has a purity of 92.35%, and a recovery rate of 85.45%.

[0112] Example 2

[0113] This embodiment is a preparation method of Momordica grosvenori leaf extract, which consists of the following steps:

[0114] S1. Mixing 100 kg of Momordica grosvenori leaf raw material with a 50% by volume ethanol aqueous solution and performing continuous countercurrent extraction once to obtain an extract;

[0115] The temperature of continuous countercurrent extraction was 60°C, the mass volume ratio of Momordica grosvenori leaf raw material and ethanol aqueous solution was 1 g:8 mL, and the extraction time was 4 h.

[0116] The extract was concentrated under reduced pressure to 1 / 15 of its original volume and diluted with water to prepare a first aqueous phase (concentration 0.6 g / mL (amount of raw material / solution));

[0117] The first aqueous phase was passed through a ceramic membrane with a molecular weight cut-off of 100 kDa, and the filtrate was collected.

[0118] S2. The filtrate obtained in step S1 was passed through AB-8 macroporous adsorption resin. After adsorption, water and 50% by volume aqueous ethanol were used for elution, respectively. The ethanol aqueous solution eluate was collected, concentrated to remove ethanol, and then diluted with water to obtain a dilution solution (containing kaempferol content of 10 mg / mL).

[0119] S3, passing the diluted solution from step S2 through a XAD-9 polar macroporous resin column. After loading, eluting with water, 20% by volume ethanol aqueous solution, and 40% by volume ethanol aqueous solution in sequence;

[0120] collecting the ethanol aqueous solution eluate with a volume fraction of 20% to obtain the Momordica grosvenori extract;

[0121] collecting the 40% ethanol aqueous solution eluate to prepare the kaempferol extract;

[0122] The mogroflavin extract was concentrated and then water was added to prepare a dilution solution (the content of mogroflavin was 9 mg / mL);

[0123] S4. After the dilution in step S3 passes through a 30 kDa ceramic membrane, the filtrate passes through a polyamide column. After the column is loaded, water and a 50% ethanol aqueous solution are used for elution in sequence. The ethanol eluate is collected, concentrated and dried to obtain the Momordica grosvenori extract (light yellow powder).

[0124] S5, concentrating the kaempferol extract in step S3 to 15% of its original volume, and then adding 95% ethanol until the volume fraction of ethanol in the solution is 90%; heating to dissolve, filtering while hot, taking the filtrate and cooling it at 10° C. for crystallization, standing it for 12 hours, and collecting the first crystals by solid-liquid separation;

[0125] The first crystals were mixed with a 90% ethanol aqueous solution (the weight-to-volume ratio of the first crystals to the 90% ethanol aqueous solution was 1 g: 18 mL), heated to dissolve (at 55°C), filtered while hot, and the filtrate was cooled at 10°C for crystallization. After standing for 12 hours, the second crystals were collected by solid-liquid separation.

[0126] The second crystals were mixed with a 90% ethanol aqueous solution (the weight-to-volume ratio of the second crystals to the 90% ethanol aqueous solution was 1 g: 18 mL), heated to dissolve (at 55°C), filtered while hot, and the filtrate was cooled at 10°C for crystallization. After standing for 12 hours, the third crystals were collected by solid-liquid separation and dried to obtain a kaempferol extract (off-white crystals).

[0127] The color of the Momordica grosvenori extract in this embodiment is light yellow, the mass is 467.25g, the purity is 71.25%, and the recovery rate is 83.19%;

[0128] The kaempferol extract in this example is off-white in color, has a mass of 2.81 kg, a purity of 93.58%, and a recovery rate of 84.69%.

[0129] Example 3

[0130] This embodiment is a preparation method of Momordica grosvenori leaf extract, which consists of the following steps:

[0131] S1. Mixing 500 kg of Momordica grosvenori leaf raw material with a 60% by volume ethanol aqueous solution and performing continuous countercurrent extraction once to obtain an extract;

[0132] The temperature of continuous countercurrent extraction was 40°C, the mass volume ratio of Momordica grosvenori leaf raw material to ethanol aqueous solution was 1 g:4 mL, and the extraction time was 5 h.

[0133] The extract was concentrated under reduced pressure to 1 / 15 of its original volume and diluted with water to prepare a first aqueous phase (concentration of 0.5 g / mL (amount of raw material / solution));

[0134] The first aqueous phase was passed through a ceramic membrane with a molecular weight cut-off of 80 kDa, and the filtrate was collected.

[0135] S2. The filtrate obtained in step S1 was passed through AB-8 macroporous adsorption resin. After adsorption, water and 60% ethanol aqueous solution were used for elution, respectively. The ethanol aqueous solution eluate was collected, concentrated to remove ethanol, and then diluted with water to obtain a dilution solution (containing kaempferol content of 8 mg / mL).

[0136] S3, passing the diluted solution obtained in step S2 through an ADS-7 polar macroporous resin column, and after the column is loaded, eluting with water, 15% by volume ethanol aqueous solution, and 35% by volume ethanol aqueous solution in sequence;

[0137] collecting the 15% volume fraction ethanol aqueous solution eluate to obtain the Momordica grosvenori extract;

[0138] collecting the 35% ethanol aqueous solution eluate to prepare the kaempferol extract;

[0139] The mogroflavin extract was concentrated and then water was added to prepare a dilution solution (the content of mogroflavin was 10 mg / mL);

[0140] S4. After the dilution in step S3 passes through a 30 kDa ceramic membrane, the filtrate passes through a polyamide column. After the column is loaded, water and a 60% ethanol aqueous solution are used for elution in sequence. The ethanol eluate is collected, concentrated and dried to obtain the Momordica grosvenori extract (light yellow powder).

[0141] S5, concentrating the kaempferol extract in step S3 to 35% of its original volume, and then adding 95% ethanol until the volume fraction of ethanol in the solution is 85%; heating to dissolve, filtering while hot, taking the filtrate and cooling it at 8°C for crystallization, standing it for 10 hours, and collecting the first crystals by solid-liquid separation;

[0142] The first crystals were mixed with an 85% ethanol aqueous solution (the weight-to-volume ratio of the first crystals to the 85% ethanol aqueous solution was 1 g: 20 mL), heated to dissolve (at 60°C), filtered while hot, and the filtrate was cooled at 8°C for crystallization. After standing for 10 hours, the second crystals were collected by solid-liquid separation.

[0143] The second crystals were mixed with an 85% ethanol aqueous solution (the weight-to-volume ratio of the second crystals to the 85% ethanol aqueous solution was 1 g: 20 mL), heated to dissolve (at 60°C), filtered while hot, and the filtrate was cooled at 8°C for crystallization. After standing for 10 hours, the third crystals were collected by solid-liquid separation and dried to obtain a kaempferol extract (off-white crystals).

[0144] The color of the Momordica grosvenori extract in this embodiment is light yellow, the mass is 2.25 kg, the purity is 73.14%, and the recovery rate is 81.57%;

[0145] The kaempferol extract in this example is off-white in color, has a mass of 13.68 kg, a purity of 94.12%, and a recovery rate of 83.01%.

[0146] In summary, the present invention provides, for the first time, a method for simultaneously preparing kaempferol and mogroflavin from Momordica grosvenori leaves, which is conducive to better utilization of the Momordica grosvenori leaves that would otherwise be discarded. The present invention uses a macroporous resin as a separation medium. After separation by combining the resin with a crystallization method, a kaempferol product with a purity greater than 90% and a mogroflavin product with a purity greater than 70% can be obtained, and the recovery rate is higher than 80%. The process is simple, no toxic organic reagents are used throughout the process, and industrial production is easy.

[0147] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a Momordica grosvenori leaf extract, characterized in that: The following steps are involved: S1. Extracting the Momordica grosvenori leaf raw material with an ethanol-water solution to prepare an extract; The extract is concentrated, water is added, and the extract is filtered to obtain a first aqueous phase; S2, passing the first aqueous phase through a macroporous resin column, eluting with water and an ethanol aqueous solution with a volume fraction of 40% to 60%, and collecting the ethanol eluate; The ethanol eluate is concentrated and then water is added to prepare a diluent; S3, passing the dilution solution through a polar macroporous resin column, sequentially using water, 10% to 20% ethanol aqueous solution and 30% to 40% ethanol aqueous solution; Collecting the ethanol aqueous solution eluate with a volume fraction of 10% to 20% to prepare the Momordica grosvenori elution solution; collecting an ethanol aqueous solution eluate with a volume fraction of 30% to 40% to prepare a kaempferol eluate; S4, concentrating the Momordica grosvenori eluate, adding water, and filtering to obtain a second aqueous phase; Passing the second aqueous phase through a polyamide resin, eluting with water and an ethanol aqueous solution with a volume fraction of 40% to 60%, collecting the ethanol eluate; concentrating the ethanol eluate and then drying it to obtain a Momordica grosvenori extract; S5, concentrating the kaempferol eluate and adding 85% to 95% ethanol aqueous solution for crystallization to obtain crude kaempferol; recrystallizing the crude kaempferol to obtain a kaempferol extract; The macroporous resin column in step S2 is one of DM130 macroporous resin column, AB-8 macroporous resin column and DM-301 macroporous resin column; The polar macroporous resin column in step S3 is one of ADS-7 macroporous resin column, DA-201 macroporous resin column and XAD-9 macroporous resin column.

2. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The extraction temperature in step S1 is 50°C to 65°C.

3. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The filtration in step S1 uses a ceramic membrane; The molecular weight cut-off of the ceramic membrane is 50 kDa to 100 kDa.

4. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The filtration in step S4 is performed using a ceramic membrane; the molecular weight cut-off of the ceramic membrane is 20 kDa to 50 kDa.

5. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The crystallization temperature in step S5 is 4°C to 10°C.

6. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The crystallization time in step S5 is 6 h to 12 h.

7. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The crystallization temperature in the recrystallization in step S5 is 4°C to 10°C.

8. The method for preparing the Momordica grosvenori leaf extract according to claim 1, wherein The solvent used for the recrystallization in step S5 is an ethanol aqueous solution with a volume fraction of 85% to 95%.

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