Preparation method of cepharanthine

Abstract

The invention discloses a preparation method of cepharanthine. The method comprises the following steps: coarsely crushing a medicinal material or decoction piece of a root tuber of the Jinghua tortoise, carrying out acid extraction, alkali precipitation and drying to obtain a crude extract, carrying out ethanol reflux extraction on the crude extract to obtain total alkali, and carrying out polystyrene type small-hole resin column chromatography on the total alkali to obtain cepharanthine. The method is simple in technological process, short in extraction and separation period, environment-friendly, low in cost and easy for industrial production.

Description

Technical Field

[0001] The invention relates to a method for extracting and separating natural products, in particular to a method for preparing stephania cepharantha from root medicinal materials or decoction pieces of Stephania cepharantha Hayata, and belongs to the field of natural product extraction and separation technology. Background Art

[0002] Cepharanthine is a natural bisbenzylisoquinoline alkaloid (BBIQ) originally discovered and named by Japanese scientists in 1934. Cepharanthine can promote bone marrow proliferation, thereby increasing white blood cell counts. It is primarily used to treat agranulocytosis caused by tumor radiotherapy and chemotherapy, as well as leukopenia caused by other causes. Cepharanthine is primarily derived from plants of the genus Stephania in the Menispermaceae family, such as Stephania cepharantha Hayata (also known as Stephania headflower, mountain turtle, or white medicine fruit), Stephania japonica Thunb Miers, and Stephania epigaea Lo.

[0003] Tong Yigang et al. isolated and cultured animal-derived novel coronavirus-like viruses to establish a cell culture model, screened about 3,000 monomer compounds including marketed drugs, and found that cephalothin can simultaneously inhibit the entry and post-entry processes of coronaviruses, suggesting that cephalothin can be used as a potential drug for the treatment of novel coronavirus infection [see, The Chinese Medical Journal (English version of the Chinese Medical Journal). 2020, 133, 1051-1056]. Ohashi et al. conducted a study on the combined use of cephalothin and nelfinavir and found that the use of cephalothin or nelfinavir alone can reduce the level of viral RNA, and the combination of the two can reduce the level of viral RNA to a lower level [see, iScience (Interdisciplinary Science). 2021, 24, 102367]. The study of Drayman et al. showed that among 1,900 existing clinical drugs, cephalothin has the best in vitro inhibitory activity against the novel coronavirus, and its EC inhibition of A549-ACE2 cells is 1. 50The EC50 of celastrol is only 0.1 μmol / L, while the EC50 of remdesivir is 0.72 μmol / L [see, Science. 2021, 373, 931-936]. In addition, by evaluating the anti-COVID-19 effect of celastrol in hACE2 transgenic mice, it was found that celastrol can exert its anti-COVID-19 effect at a lower concentration, with good efficacy and safety. It also has anti-inflammatory effects and can reduce lung damage caused by viral infection [see, Cell Research. 2022, 32, 9-23]. In view of the potential application value of celastrol in anti-COVID-19 infection, it is necessary to develop a simpler, more efficient, environmentally friendly and industrially scalable celastrol extraction process.

[0004] The existing cephalanthrin extraction process requires the use of volatile organic solvents such as chloroform, ethyl acetate, methanol or acetone. A large amount of hazardous organic reagents will be generated during the production process. The cost of hazardous waste treatment and the safety risk of operators are high, and it is difficult to operate on the same line as the existing production line.

[0005] Therefore, it is of great significance to develop a preparation method for cephalanthrin that is simple, economical, green and environmentally friendly, and can better meet the requirements of mass industrial production. Summary of the Invention

[0006] In response to the defects of the prior art, the present invention provides a method for preparing cepharanthin. This method does not require the use of volatile organic solvents such as chloroform, ethyl acetate, methanol or acetone, thus avoiding the generation of large amounts of hazardous organic waste or acid-base waste liquids. The polystyrene-type small-pore resin used can be reused, and no pressurization or decompression is required during the elution process. The preparation process is simple, feasible, environmentally friendly, and more likely to meet the requirements of large-scale industrial production.

[0007] The preparation method of cepharanthin provided by the present invention comprises the following steps:

[0008] 1) coarsely chopping the root tuber or slices of Stephania cepharantha Hayata, then soaking or extracting the coarsely chopping root tuber or slices with a low-concentration acid solution, and filtering to obtain an acid-water extract;

[0009] 2) adding a low-concentration alkaline solution to the acid-water extract of step 1), adjusting the pH to 9-11, standing until precipitation is complete, centrifuging, discarding the supernatant, collecting the precipitate and drying it to obtain a crude extract of the medicinal material;

[0010] 3) extracting the crude extract obtained in step 2) by heating under reflux with ethanol or ethanol-water solution as an extractant, collecting the extract, filtering, concentrating under reduced pressure, and evaporating the solvent to obtain total alkaloids;

[0011] 4) The total alkaloids obtained in step 3) were dissolved in anhydrous ethanol and chromatographed on a polystyrene small-pore resin column using a gradient elution method with a 20% to 85% ethanol-water solution as the eluent. The eluates containing cepharanthin were combined and the solvent was evaporated under reduced pressure to obtain cepharanthin.

[0012] In step 1) of the above method, the low-concentration acid aqueous solution can be a hydrochloric acid aqueous solution with a mass fraction of 0.1%-5% (specifically 0.3%) or a sulfuric acid aqueous solution with a mass concentration of 0.1%-5% (specifically 0.3%).

[0013] In step 1) of the above method, the material-liquid ratio of the medicinal material or decoction piece to the acid aqueous solution is 1:5 to 1:50 (m:V).

[0014] In step 1) of the above method, the soaking conditions are room temperature and soaking for 4-24 hours; the percolation extraction conditions are room temperature, soaking for 4-24 hours, and percolation time for 2-4 hours.

[0015] In step 2) of the above method, the low-concentration alkaline solution can be a sodium hydroxide aqueous solution, a calcium hydroxide aqueous solution or a potassium hydroxide aqueous solution with a mass fraction of 1 to 10% (specifically 5%).

[0016] In step 2) of the above method, the drying temperature range is 40-80°C.

[0017] In step 3) of the above method, the volume fraction of ethanol in the ethanol solution is 90% to 100% (but not including 100%).

[0018] In step 3) of the above method, the reflux extraction conditions are: solid-liquid ratio 1:20-1:400 (m:V), extraction 1-4 times, and each extraction time is 30 min-120 min.

[0019] In step 4) of the above method, the material-liquid ratio of the total alkaloids to anhydrous ethanol is 1:1 to 1:20 (m:V), specifically 1:5.

[0020] In step 4) of the above method, the polystyrene small-pore resin is one of MCIGEL CHP resin, Amberchrom CG161 resin or Positisil PS MCI resin.

[0021] Furthermore, the MCIGEL CHP resin may be MCIGEL CHP20 / P120; the Amberchrom CG161 resin may be CG161; and the Positisil PS MCI resin may be Positisil PS MCI 75-120 μm.

[0022] In step 4) of the above method, the diameter-to-height ratio of the chromatography column is 1:(2-20), specifically 1:4, 1:5 or 1:6.

[0023] In step 4) of the above method, the elution gradient of the gradient elution is: 20% ethanol-water solution, 40% ethanol-water solution, 60% ethanol-water solution, 70% ethanol-water solution, 80% ethanol-water solution, and 85% ethanol-water solution; each gradient elution is 2-12 times the column volume; according to the thin layer chromatography detection results of the eluates of each part, the 80% and 85% ethanol-water solution eluates are combined, and the solvent is evaporated under reduced pressure to obtain cepharanthin.

[0024] Furthermore, the developing solvent of the thin layer chromatography is ethyl acetate:methanol (V:V)=1:1, and the thin layer color development method is modified potassium bismuth iodide color development, or silica gel GF254 plate is observed under ultraviolet light at 254nm.

[0025] The content of stephaniocin in the present invention is determined by HPLC detection, and the specific detection method is as follows:

[0026] 1. Chromatographic conditions:

[0027] Using Cosmosil 5C 18 -MS-Ⅱ chromatographic column, with 0.1% triethylamine aqueous solution (A): methanol (B) = 25:75 as the mobile phase; detection wavelength: 282 nm; flow rate: 1 mL / min; column temperature: 30°C; injection volume: 10 μL.

[0028] 2. Sample preparation:

[0029] 1. Preparation of reference solution

[0030] Accurately weigh 6.27 mg of cephalaenopsisin reference substance (China Food and Drug Inspection Institute, batch number: 111647-202202, purity 98.6%), place it in a 25 mL volumetric flask, add 20 mL of methanol, ultrasonically dissolve for 10 min, cool to room temperature, add methanol to make up to 25 mL, and prepare a reference substance solution with a concentration of 0.25 mg / mL.

[0031] 2. Test solution

[0032] Accurately weigh the test sample (determine the weighing amount according to the specific content) into a 5 mL volumetric flask, add 4 mL of methanol, sonicate and dissolve for 10 min, cool to room temperature, and then add methanol to make up to 5 mL.

[0033] 3. Sample determination and content calculation:

[0034] Pipette about 200 μL of reference substance and test substance solution respectively, add them into liquid chromatography sample bottle, set the injection volume to 10 μL, measure, and calculate the content of cepharanthin by external standard method.

[0035]

[0036] in:

[0037] C 标样 is the content of cepharanthin standard solution

[0038] C 供试品 is the content of the test solution

[0039] A 供试品 is the chromatographic peak area of ​​the test sample

[0040] A 标准品 is the peak area of ​​cepharanthin standard

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The preparation process of the present invention is simple, with a short extraction and separation cycle. During the separation process, only ethanol is used as the organic solvent, eliminating the need for other toxic and hazardous volatile organic solvents. Furthermore, the ethanol used as the eluent for polystyrene-based small-pore resin column chromatography is recyclable and reusable. This process is environmentally friendly, has minimal risk of being co-located with existing equipment, and offers low production and hazardous waste disposal costs. The polystyrene-based small-pore resin used for separation has a moderate particle size, meeting separation requirements without the need for pressurization or decompression, resulting in greater energy efficiency and ease of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention is a process flow chart for preparing Stephania tetrandra.

[0044] Figure 2 This is the HPLC chromatogram of the total alkali sample obtained by acid extraction and alkali precipitation in Example 1.

[0045] Figure 3 This is the HPLC detection chromatogram of the cepharanthin standard.

[0046] Figure 4 This is the HPLC chromatogram for detecting the cepharanthin prepared in Example 1.

[0047] Figure 5 This is the HPLC chromatogram for detecting the stephania tenuifolia prepared in Example 2.

[0048] Figure 6 This is the HPLC chromatogram for detecting the cepharanthin prepared in Example 3.

[0049] Figure 7This is the HPLC chromatogram of the cepharanthin prepared in Comparative Example 1.

[0050] Figure 8 This is the HPLC chromatogram for detecting the cepharanthin prepared in Comparative Example 2.

[0051] Figure 9 This is the HPLC chromatogram for detecting the cepharanthin prepared in Comparative Example 3. DETAILED DESCRIPTION

[0052] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be appreciated by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. In the examples, if no specific conditions are specified, the conditions are followed according to conventional conditions or manufacturer recommendations. Reagents or instruments used that do not specify the manufacturer are all commercially available conventional products.

[0053] Example 1 Separation of Cephalaenopsis in MCIGEL CHP20 / P120 Resin Column Chromatography

[0054] 1) Take 3.5 kg of the root tuber of the golden thread turtle, chop it twice, the first time without a sieve, and the second time with a 0.8 cm pore size sieve, add 20 times the amount of 0.3% sulfuric acid solution (m / V) at room temperature for percolation extraction, filter the extract to obtain the acid water extract.

[0055] 2) The acid-water extract obtained in step 1) was added dropwise with stirring to a 5% by mass aqueous sodium hydroxide solution until the pH reached 10. A precipitate gradually formed during the addition. After the addition was completed, the mixture was allowed to stand for 1 hour, centrifuged, and the supernatant was discarded to obtain a precipitate. The precipitate was dried to obtain a crude extract.

[0056] 3) taking the crude extract from step 2), adding 200 times the amount of anhydrous ethanol (m / v), heating to reflux, extracting for 2 hours, filtering while hot, combining the filtrates and evaporating the solvent under reduced pressure to obtain total alkaloids.

[0057] 4) After the total alkaloids were dissolved in a small amount of anhydrous ethanol (solid-liquid ratio of 1:5), they were chromatographed on a MCIGEL CHP20 / P120 resin (average particle size 120 μm) column with a filler diameter-to-height ratio of 1:6. After loading, the sample was eluted with 2 column volumes of 20%, 40%, and 60% ethanol aqueous solutions, then eluted with 4 column volumes of 70% ethanol aqueous solution, and the eluent was discarded; then eluted with 12 column volumes of 80% ethanol aqueous solution, and finally eluted with 85% ethanol aqueous solution. The 80% and 85% ethanol aqueous solution eluates were combined according to the results of thin-layer chromatography, and the solvent was evaporated under reduced pressure to obtain 22.90 g of cepharanthin, which had a purity of 90.9% as determined by HPLC.

[0058] Example 2 Separation of Cephalaenopsis in CG161 Resin Column Chromatography

[0059] 1) Take 3.5 kg of the root tuber of the golden thread turtle, chop it twice, the first time without a sieve, and the second time with a 0.8 cm pore size sieve, add 20 times the amount of 0.3% sulfuric acid solution (m / V) at room temperature for percolation extraction, filter the extract to obtain the acid water extract.

[0060] 2) The acid-water extract obtained in step 1) was added dropwise with stirring to a 5% by mass aqueous sodium hydroxide solution until the pH reached 10. A precipitate gradually formed during the addition. After the addition was completed, the mixture was allowed to stand for 1 hour, centrifuged, and the supernatant was discarded to obtain a precipitate. The precipitate was dried to obtain a crude extract.

[0061] 3) Take the crude extract from step 2), add 200 times the amount of anhydrous ethanol (m / v), heat and reflux, extract for 2 hours, filter while hot, and evaporate the filtrate under reduced pressure to dry the solvent to obtain total alkali.

[0062] 4) After the total alkali was dissolved with a small amount of anhydrous ethanol (solid-liquid ratio of 1:5), it was chromatographed on a CG161c resin (average particle size 120 μm) column with a filler diameter-to-height ratio of 1:4. After loading, the sample was eluted with 2 column volumes of 20%, 40%, and 60% ethanol aqueous solutions, then eluted with 4 column volumes of 70% ethanol aqueous solution, and the eluent was discarded; then eluted with 12 column volumes of 80% ethanol aqueous solution, and finally eluted with 85% ethanol aqueous solution. The 80% and 85% ethanol aqueous solution eluates were combined after TLC analysis, and the solvent was evaporated under reduced pressure to obtain 9.70 g of cepharanthin, which had a purity of 93.0% as determined by HPLC.

[0063] Example 3: Separation of Cephalaenopsis by Positisil PS MCI Resin Column Chromatography

[0064] 1) Take 3.5 kg of the root tuber of the golden thread turtle, chop it twice, the first time without a sieve, and the second time with a 0.8 cm pore size sieve, add 20 times the amount of 0.3% sulfuric acid solution (m / V) at room temperature for percolation extraction, filter the extract to obtain the acid water extract.

[0065] 2) The acid-water extract obtained in step 1) was added dropwise with stirring to a 5% by mass aqueous sodium hydroxide solution until the pH reached 10. A precipitate gradually formed during the addition. After the addition was completed, the mixture was allowed to stand for 1 hour, centrifuged, and the supernatant was discarded to obtain a precipitate. The precipitate was dried to obtain a crude extract.

[0066] 3) taking the crude extract from step 2), adding 200 times the amount of anhydrous ethanol (m / v), heating to reflux, extracting for 2 hours, filtering while hot, and evaporating the filtrate under reduced pressure to dry the solvent to obtain total alkaloids.

[0067] 4) After the total alkaloids were dissolved in a small amount of anhydrous ethanol (solid-to-liquid ratio of 1:5), they were chromatographed on a Positisil PS MCI resin (particle size 75-120 μm) column with a filler diameter-to-height ratio of 1:5. After loading, the sample was eluted with 2 column volumes of 20%, 40%, and 60% ethanol aqueous solutions, then eluted with 4 column volumes of 70% ethanol aqueous solution, and the eluent was discarded; then eluted with 12 column volumes of 80% ethanol aqueous solution, and finally eluted with 85% ethanol aqueous solution. The 80% and 85% ethanol aqueous solution eluates were combined after TLC analysis, and the solvent was evaporated under reduced pressure to obtain 7.88 g of cepharanthin, which had a purity of 92.5% as determined by HPLC.

[0068] Comparative Example 1: Separation of Cephalaenopsis in Silica Gel Column

[0069] 1) Take 3.5 kg of the root tuber of the golden thread turtle, chop it twice, the first time without a sieve, and the second time with a 0.8 cm pore size sieve, add 20 times the amount of 0.3% sulfuric acid solution (m / V) at room temperature for percolation extraction, filter the extract to obtain the acid water extract.

[0070] 2) The acid-water extract obtained in step 1) was added dropwise with stirring to a 5% by mass aqueous sodium hydroxide solution until the pH reached 10. A precipitate gradually formed during the addition. After the addition was completed, the mixture was allowed to stand for 1 hour, centrifuged, and the supernatant was discarded to obtain a precipitate. The precipitate was dried to obtain a crude extract.

[0071] 3) taking the crude extract from step 2), adding 200 times the amount of anhydrous ethanol (m / v), heating to reflux, extracting for 2 hours, filtering while hot, and evaporating the filtrate under reduced pressure to dry the solvent to obtain total alkaloids.

[0072] 4) The total alkali was dissolved in methanol and mixed with an equal mass of 100-200 mesh silica gel. The sample was then wet-packed on a silica gel column and eluted with 20 column volumes of dichloromethane-methanol = 20:1 (v / v). Based on the TLC test results, the elution fraction rich in cepharanthin was collected to obtain 8.95 g of cepharanthin, which had a purity of 80.2% as determined by HPLC.

[0073] Comparative Example 2: Separation of Cephalaenopsis in Alkaline Alumina Column

[0074] 1) Take 3.5 kg of the root tuber of the golden thread turtle, chop it twice, the first time without a sieve, and the second time with a 0.8 cm pore size sieve, add 20 times the amount of 0.3% sulfuric acid solution (m / V) at room temperature for percolation extraction, filter the extract to obtain the acid water extract.

[0075] 2) The acid-water extract obtained in step 1) was added dropwise with stirring to a 5% by mass aqueous sodium hydroxide solution until the pH reached 10. A precipitate gradually formed during the addition. After the addition was completed, the mixture was allowed to stand for 1 hour, centrifuged, and the supernatant was discarded to obtain a precipitate. The precipitate was dried to obtain a crude extract.

[0076] 3) taking the crude extract from step 2), adding 200 times the amount of anhydrous ethanol (m / v), heating to reflux, extracting for 2 hours, filtering while hot, and evaporating the filtrate under reduced pressure to dry the solvent to obtain total alkaloids.

[0077] 4) The total alkaloids were dissolved in methanol and mixed with 4 times the amount of basic alumina. The sample was then wet-packed and eluted on a basic alumina column (column diameter-to-height ratio of 1:15) with petroleum ether-acetone = 20:1 (v / v). Based on the TLC analysis results, the elution fraction rich in cepharanthin was collected to obtain 6.98 g of cepharanthin, which had a purity of 88.1% as determined by HPLC.

[0078] Comparative Example 3: Separation of Stephania tetrandra by ODS C18 reverse phase chromatography column

[0079] 1) Take 3.5 kg of the root tuber of the golden thread turtle, chop it twice, the first time without a sieve, and the second time with a 0.8 cm pore size sieve, add 20 times the amount of 0.3% sulfuric acid solution (m / V) at room temperature for percolation extraction, filter the extract to obtain the acid water extract.

[0080] 2) The acid-water extract obtained in step 1) was added dropwise with stirring to a 5% by mass aqueous sodium hydroxide solution until the pH reached 10. A precipitate gradually formed during the addition. After the addition was completed, the mixture was allowed to stand for 1 hour, centrifuged, and the supernatant was discarded to obtain a precipitate. The precipitate was dried to obtain a crude extract.

[0081] 3) taking the crude extract from step 2), adding 200 times the amount of anhydrous ethanol (m / v), heating to reflux, extracting for 2 hours, filtering while hot, and evaporating the filtrate under reduced pressure to dry the solvent to obtain total alkaloids.

[0082] 4) After the total alkali was dissolved in a small amount of ethanol, the sample was wet loaded and chromatographed on an ODS reverse-phase C18 (particle size 50 μm) medium-pressure column with a filler diameter-to-height ratio of 1:10. After loading, the sample was eluted with 4 column volumes of 10%, 30%, 50%, 70%, and 90% ethanol aqueous solutions, respectively. The 70% ethanol aqueous eluate was combined after TLC analysis, and the solvent was evaporated under reduced pressure to obtain 10.65 g of cepharanthin, which had a purity of 86.7% as determined by HPLC.

[0083] Table 1. Summary of results of Examples 1-3 and Comparative Examples 1-3

[0084]

[0085] In Table 1, the calculation formula of the transfer rate is: cephalanthone yield×cephalanthone purity×100% / (herbal material weight×cephalanthone content in herbal material).

[0086] The results of Examples 1-3 and Comparative Examples 1-3 indicate that cepharanthin with a purity greater than 90% can be obtained using polystyrene small-pore resin column chromatography, with MCIGEL CHP20 / P120 resin exhibiting the highest cepharanthin transfer efficiency. The purity of cepharanthin obtained using polystyrene small-pore resin column chromatography was higher than that obtained using silica gel, basic alumina, and ODS C18 column chromatography.

[0087] In summary, the present invention provides a process for preparing total alkaloids by acid extraction, alkali precipitation, and ethanol reflux, and then subjecting the total alkaloids to polystyrene type small pore resin column chromatography to prepare cepharanthin with a purity greater than 90%. In the extraction and separation process of this method, only water, an appropriate amount of low-concentration acid and alkali solution, anhydrous or 95% ethanol are required. The ethanol used can be reused after recovery, and the generation of a large amount of organic hazardous waste or acid and alkali waste liquid is avoided during the extraction and separation process. The particle size range of the polystyrene type small pore resin used is moderate, and no pressurization or decompression is required during the column chromatography process, which is more energy-saving and safe, and can be used repeatedly. The preparation process is simple, economical, green and environmentally friendly, and can better meet the requirements of mass industrial production.

[0088] The present invention has been described in detail above. It will be apparent to those skilled in the art that the present invention may be practiced over a wide range of parameters, concentrations, and conditions without departing from the spirit and scope of the present invention and without unnecessary experimentation. Although specific embodiments have been given herein, it should be understood that further modifications may be made to the present invention. In summary, this application is intended to encompass any variations, uses, or improvements to the present invention, including those made by conventional techniques known in the art that depart from the scope of the present invention. Applications of the essential features may be made within the scope of the following claims.

Claims

1. A method for preparing cepharanthin, comprising the following steps: 1) coarsely chopping the root tuber or slices of Stephania cepharantha Hayata, then soaking or extracting the coarsely chopping root tuber or slices with a low-concentration acid solution, and filtering to obtain an acid-water extract; 2) adding a low-concentration alkaline solution to the acid-water extract of step 1), adjusting the pH to 9-11, standing until precipitation is complete, centrifuging, discarding the supernatant, collecting the precipitate and drying it to obtain a crude extract of the medicinal material; 3) extracting the crude extract obtained in step 2) by heating under reflux using ethanol or an ethanol solution as an extractant, collecting the extract, filtering, concentrating under reduced pressure, and evaporating the solvent to obtain total alkaloids; 4) The total alkaloids obtained in step 3) were dissolved in anhydrous ethanol and chromatographed on a polystyrene small-pore resin column using a gradient elution method with a 20% to 85% ethanol-water solution as the eluent. The eluates containing cepharanthin were combined and the solvent was evaporated under reduced pressure to obtain cepharanthin.

2. The preparation method according to claim 1, wherein: In the step 1), the low-concentration acid aqueous solution is a hydrochloric acid aqueous solution with a mass fraction of 0.1%-5% or a sulfuric acid aqueous solution with a mass concentration of 0.1%-5%; And / or, in step 1), the material-liquid ratio of the medicinal material or decoction piece to the acid aqueous solution is 1:5 to 1:50 (m:V); And / or, in the step 1), the soaking condition is room temperature for 4-24 hours; the percolation extraction condition is room temperature for 4-24 hours, and the percolation time is 2-4 hours.

3. The preparation method according to claim 1 or 2, characterized in that: In the step 2), the low-concentration alkaline solution is a sodium hydroxide aqueous solution, a calcium hydroxide aqueous solution or a potassium hydroxide aqueous solution with a mass fraction of 1 to 10%.

4. The preparation method according to any one of claims 1 to 3, characterized in that: In step 3), the volume fraction of ethanol in the ethanol solution is 90% to 100%, but not including 100%; And / or, the reflux extraction conditions are: solid-liquid ratio 1:20-1:400 (m:V), extraction 1-4 times, and each extraction time is 30 min-120 min.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step 4), the material-liquid ratio of the total alkaloids to anhydrous ethanol is 1:1 to 1:20 (m:v).

6. The preparation method according to any one of claims 1 to 5, characterized in that: In the step 4), the polystyrene small-pore resin is one of MCIGEL CHP resin, Amberchrom CG161 resin or Positisil PS MCI resin.

7. The preparation method according to claim 6, characterized in that: The MCIGEL CHP resin is MCIGEL CHP20 / P120; Or, the Amberchrom CG161 resin is CG161c; Alternatively, the Positisil PS MCI resin is Positisil PS MCI 75-120 μm.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In the step 4), the diameter-to-height ratio of the chromatography column is 1:(2-20).

9. The preparation method according to any one of claims 1 to 8, characterized in that: In the step 4), the elution gradient of the gradient elution is: 20% ethanol-water solution, 40% ethanol-water solution, 60% ethanol-water solution, 70% ethanol-water solution, 80% ethanol-water solution, and 85% ethanol-water solution; each gradient elution is 2-12 times the column volume; according to the thin layer chromatography detection results of each part of the eluate, the 80% and 85% ethanol-water solution eluates are combined, and the solvent is evaporated under reduced pressure to obtain cepharanthin.

10. The preparation method according to claim 9, characterized in that: The developing solvent of the thin layer chromatography is ethyl acetate:methanol (V:V)=1:1, and the thin layer color development method is modified potassium bismuth iodide color development, or silica gel GF254 plate is observed under ultraviolet light at 254nm.

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