Fresh rehmannia root decoction pieces as well as preparation method and quality control method thereof

Abstract

The invention relates to the field of traditional Chinese medicines, in particular to fresh rehmannia decoction pieces as well as a preparation method and a quality control method thereof. On the basis of the traditional fresh rehmannia decoction pieces, the processing method of the fresh rehmannia decoction pieces is optimized by taking the external properties, the catalpol content, the rehmannia glycoside D content and the stachyose content as evaluation indexes, and the processing method comprises the following steps: slicing a fresh rehmannia medicinal material, boiling in boiling water for 1-10 minutes, fishing out, and drying at 45-80 DEG C for 24 hours to obtain the fresh rehmannia decoction pieces. The invention provides a basis for production, processing and market development of the fresh rehmannia root decoction pieces. The fresh rehmannia decoction pieces prepared by the preparation method not only meet various standards of rehmannia items in Chinese Pharmacopoeia of 2020 edition, but also have catalpol content not lower than 2.6% and stachyose content not lower than 50.0%. The preparation of the fresh rehmannia decoction pieces and the setting of the quality standard can provide the fresh rehmannia with stable and controllable quality for clinic, and the distress condition that the clinical fresh rehmannia gradually disappears because the fresh rehmannia is difficult to preserve is changed.

Description

Technical Field

[0001] The invention relates to the field of traditional Chinese medicine, and in particular to a fresh Rehmannia root slice and a preparation method and a quality control method thereof. Background Art

[0002] Fresh Rehmannia glutinosa comes from the fresh root of Rehmannia glutinosa Libosch., a plant of the Scrophulariaceae family, and was first recorded in the Shennong's Herbal Classic. Fresh medicinal materials are fresh in texture, maintain their natural state and composition structure, and have the advantages of high content of effective ingredients and excellent efficacy. Fresh Rehmannia glutinosa has a long history of clinical application in traditional Chinese medicine. For example, Baihe Dihuang Decoction and Fangji Dihuang Decoction in Zhang Zhongjing's Synopsis of the Golden Chamber, Qingying Decoction in Wu Jutong's Treatise on Warm Diseases, Xijiao Dihuang Decoction in Sun Simiao's Qianjin Yaofang, and Sisheng Pills in Chen Ziming's Complete Prescriptions for Women all use fresh Rehmannia glutinosa as medicine. According to clinical Chinese medicine, fresh Rehmannia glutinosa is sweet, bitter and extremely cold, and has the effects of clearing heat and cooling blood, nourishing yin and promoting fluid production. Its effects of clearing heat and promoting fluid production and cooling blood are better than those of raw Rehmannia glutinosa, and it is good at treating various blood-heat and bleeding syndromes such as excessive blood-heat evil, high fever, thirst, and vomiting blood, epistaxis, and coughing up blood. Modern research shows that the content of catalpol, reducing sugar, oligosaccharide and polysaccharide in fresh Rehmannia is higher than that in raw Rehmannia; fresh Rehmannia juice and fresh Rehmannia decoction have a significantly stronger effect on inducing coagulation time in mice than raw Rehmannia. Fresh Rehmannia polysaccharide can inhibit the hyperfunction of thyroid axis and adrenal axis by increasing the content of dopamine (DA) and γ-aminobutyric acid (GABA), thus playing an anti-anxiety role; at the same time, it can reduce the fever of blood heat and bleeding, improve abnormal blood rheology, and play a role in cooling blood and stopping bleeding by reducing plasma viscosity. Catalpol not only has antioxidant, anti-inflammatory and anti-apoptotic effects, but also can protect the cardiovascular and cerebrovascular system through multiple signaling pathways, and also has a significant protective effect on renal damage caused by hyperglycemia.

[0003] However, fresh Rehmannia root is less and less used in clinical TCM nowadays because it is not easy to store. In the 2020 edition of the Chinese Pharmacopoeia, "fresh Rehmannia root" and "raw Rehmannia root" are included together under the Rehmannia root item; however, in the Rehmannia root standard, fresh Rehmannia root only has properties specified, the thin layer identification item does not specify the pretreatment method, the total ash, acid-insoluble ash and extract items in the inspection item do not specify the limits of fresh Rehmannia root, and the content determination item only has the raw Rehmannia root content determination method and standard, while fresh Rehmannia root lacks the corresponding quality control method and standard. All this stems from the fact that fresh Rehmannia root is difficult to preserve. In theory, it can be used in clinical practice, but in fact there is no storable physical object for research and application. Although there are literature reports on the preparation method of fresh Rehmannia root slices, the current reported methods are all freeze-drying methods, which have high freeze-drying costs and are unaffordable for industrial preparation costs. For this reason, this method is only in experimental research. Therefore, it is urgent to develop a simple and inexpensive method for preparing fresh Rehmannia root slices that can maintain the quality of fresh Rehmannia root and formulate its quality standards to provide clinical use of fresh Rehmannia root with controllable and stable quality. Summary of the invention

[0004] The purpose of the present invention is to provide a fresh Rehmannia root slice and a preparation method and a quality control method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for preparing fresh Rehmannia root slices, comprising the steps of sequentially boiling and drying the fresh Rehmannia root slices to obtain the fresh Rehmannia root slices;

[0007] The cooking time is 1-10 min.

[0008] Preferably, the drying temperature is 45°C-80°C and the drying time is 24 hours.

[0009] Preferably, the drying method is air drying.

[0010] Preferably, the thickness of the fresh Rehmannia root slices is 2-4 mm.

[0011] The invention provides a fresh Rehmannia root slice prepared by the method.

[0012] The present invention provides a quality control method for the above-mentioned fresh Rehmannia root slices, comprising:

[0013] (1) observing the shape of the fresh Rehmannia root slices;

[0014] (2) performing powder microscopic identification on the fresh Rehmannia root slices;

[0015] (3) Testing the moisture content, total ash content, acid-insoluble ash content and extract of the fresh Rehmannia root slices; the moisture content of the fresh Rehmannia root slices shall not exceed 10.0%, the total ash content shall not exceed 4.0%, the acid-insoluble ash content shall not exceed 0.30%, and the extract content shall not be less than 65.0%;

[0016] (4) performing thin layer chromatography identification on the fresh Rehmannia root slices;

[0017] (5) The contents of catalpol, rehmannia glutinosa D and stachyose in the fresh Rehmannia glutinosa slices are detected by high performance liquid chromatography; the content of catalpol in the fresh Rehmannia glutinosa slices shall not be less than 2.6%, the content of rehmannia glutinosa D shall not be less than 0.20%, and the content of stachyose shall not be less than 50.0%.

[0018] Preferably, the thin layer chromatography identification includes method 1, method 2 and method 3;

[0019] The method 1 comprises the steps of taking a test solution and a catalpol reference solution and spotting them on a silica gel G thin layer plate, using a mixed solution of chloroform, methanol and water as a developing agent, developing, spraying anisaldehyde test solution, heating, and observing under sunlight; the preparation method of the test solution comprises the steps of mixing a sample powder to be tested with an ethanol solution, heating and refluxing, filtering and concentrating in sequence to obtain the test solution; the preparation method of the catalpol reference solution comprises the steps of mixing a catalpol reference with methanol to obtain the catalpol reference solution; the concentration of catalpol in the catalpol reference solution is 0.5 mg / mL;

[0020] The method 2 comprises the steps of taking a test solution and a verbascoside reference solution and spotting them on a silica gel G thin layer plate, using a mixed solution of ethyl acetate, methanol and formic acid as a developing agent, developing, immersing the plate with a 0.1% 2,2-diphenyl-1-picrylhydrazyl anhydrous ethanol solution, drying, and observing under sunlight; the preparation method of the test solution comprises the steps of mixing a sample powder to be tested with an ethanol solution, performing ultrasonic treatment and n-butanol extraction in sequence, to obtain the test solution; the preparation method of the verbascoside reference solution comprises the steps of mixing a verbascoside reference with methanol, to obtain the verbascoside reference solution; the concentration of verbascoside in the verbascoside reference solution is 1 mg / mL;

[0021] The method 3 comprises the steps of spotting a test solution and a reference solution containing stachyose, raffinose and sucrose on a silica gel G thin layer plate, developing with a mixed solution of glacial acetic acid, anhydrous formic acid, water and ethyl acetate as a developing agent, spraying with 10% sulfuric acid ethanol solution, heating, and observing under a 365nm ultraviolet lamp; the preparation method of the test solution comprises the steps of mixing the sample powder to be tested with the ethanol solution, performing ultrasonic treatment and filtering in sequence to obtain the test solution; the preparation method of the reference solution containing stachyose, raffinose and sucrose comprises the step of mixing a stachyose reference substance, a raffinose reference substance and a sucrose reference substance with methanol to obtain the reference solution containing stachyose, raffinose and sucrose; the concentration of stachyose in the reference solution containing stachyose, raffinose and sucrose is 1 mg / mL, the concentration of raffinose is 1 mg / mL, and the concentration of sucrose is 1 mg / mL.

[0022] Preferably, in the method 1, the volume ratio of chloroform, methanol and water in the developing solvent is 14:6:1; the heating temperature is 105° C.; the concentration of anisaldehyde in the anisaldehyde test solution is 10.7 mg / mL; the mass volume ratio of the sample powder to be tested and the ethanol solution is 1 g:20 mL;

[0023] In the method 2, the volume ratio of ethyl acetate, methanol and formic acid in the developing solvent is 16:0.5:2; the concentration of 2,2-diphenyl-1-picrylhydrazyl in the 2,2-diphenyl-1-picrylhydrazyl anhydrous ethanol solution is 0.1%; the mass volume ratio of the sample powder to be tested and the ethanol solution is 1g:50mL;

[0024] In method 3, the volume ratio of glacial acetic acid, anhydrous formic acid, water and ethyl acetate in the developing agent is 4:5:6:12; the concentration of sulfuric acid in the sulfuric acid ethanol solution is 10%; and the mass volume ratio of the sample powder to be tested and the ethanol solution is 1g:25mL.

[0025] Preferably, the thin layer chromatography identification includes method a, method b and method c;

[0026] The method a comprises the steps of taking a catalpol reference solution and a test solution, injecting them into a liquid chromatograph, and performing chromatographic detection; the method for preparing the catalpol reference solution comprises the step of mixing the catalpol reference solution and methanol to obtain the catalpol reference solution; the concentration of catalpol in the catalpol reference solution is 50 μg / mL; the method for preparing the test solution comprises the step of mixing the sample powder to be tested with methanol, and sequentially performing heating reflux extraction, filtering, concentrating, dissolving and filtering to obtain the test solution;

[0027] The method b comprises the steps of taking a rehmannia glycoside D reference solution and a test solution, injecting them into a liquid chromatograph, and performing chromatographic detection; the preparation method of the rehmannia glycoside D reference solution comprises the step of mixing the catalpol reference solution and methanol to obtain the rehmannia glycoside D reference solution; the concentration of rehmannia glycoside D in the rehmannia glycoside D reference solution is 70 μg / mL; the preparation method of the test solution comprises the step of mixing the sample powder to be tested and methanol, and sequentially performing ultrasonic treatment, centrifugation and filtration to obtain the test solution;

[0028] The method c comprises the steps of aspirating a stachyose reference solution and a test solution, injecting them into a liquid chromatograph, and performing chromatographic detection; the preparation method of the stachyose reference solution comprises the step of mixing the stachyose reference solution and methanol to obtain the stachyose reference solution; the concentration of catalpol in the stachyose reference solution is 1 mg / mL; the preparation method of the test solution comprises the step of mixing the sample powder to be tested and methanol, and performing ultrasonic treatment and filtering in sequence to obtain the test solution.

[0029] Preferably, in the method a, the chromatographic detection conditions are: using octadecylsilane bonded silica gel as a filler; the chromatographic column is XB-C 18; Column temperature was 30°C; Flow rate was 1 mL / min; Injection volume was 10 μL; Eluent was methanol-0.1% (V / V) phosphoric acid solution; Detection wavelength was 210 nm;

[0030] In the method b, the chromatographic detection conditions are: using octadecylsilane bonded silica gel as a filler; the chromatographic column is XB-C 18 ; Column temperature was 30°C; Flow rate was 1 mL / min; Injection volume was 10 μL; Eluent was methanol-0.1% phosphoric acid solution; Detection wavelength was 203 nm;

[0031] In the method c, the conditions for the chromatographic detection are: tertiary amine alkyl bonded silica gel as the filler; the chromatographic column is a COSMOSIL Sugar-D chromatographic column; the column temperature is 30°C; the flow rate is 1 mL / min; the injection volume is 10 μL; and acetonitrile-water is used as the mobile phase for elution.

[0032] The present invention discloses the following technical effects:

[0033] The invention optimizes the preparation method of fresh Rehmannia root slices based on traditional fresh Rehmannia root slices by taking appearance, catalpol content, rehmannia glycoside D content and stachyose content as evaluation indexes. The preparation method comprises the following steps: removing impurities from fresh Rehmannia root medicinal materials, washing off mud and sand, slicing (2-4 mm), boiling in boiling water for 1-10 min, taking out, and drying at 45-80° C. for 24 h to obtain fresh Rehmannia root slices. The invention provides a basis for the production, processing and market development of fresh Rehmannia root slices.

[0034] The fresh Rehmannia slices prepared by the preparation method provided by the present invention have an appearance of burnt yellow circular flakes. The outer skin is brownish yellow and slightly wrinkled; the cut surface is brownish yellow, the cortex is light yellow-red, with occasional orange-red oil spots, and the wood is yellowish-white; the smell is slight and the taste is slightly bitter; the powder of the fresh Rehmannia slices is light yellow; the cork cells are light yellow; the thin-walled cells are round, containing round-like nuclei, and the secretory cells are similar to general thin-walled cells, containing orange-yellow or orange-red oil droplets; the diameter of the bordered pit vessels and reticulated vessels is about 92μm. The fresh Rehmannia slices prepared by the preparation method provided by the present invention not only meet the various standards under the Rehmannia item of the 2020 edition of the "Chinese Pharmacopoeia", but also have a catalpol content of not less than 2.6%, and spots of corresponding colors appear at the same position as the reference substances stachyose, raffinose and sucrose on the thin layer chromatogram, and the stachyose content is not less than 50.0%. The preparation of fresh Rehmannia root slices and the formulation of quality standards can provide fresh Rehmannia root with stable and controllable quality for clinical use, thus changing the embarrassing situation that fresh Rehmannia root is gradually extinct in clinical use due to its difficulty in preservation. Meanwhile, the present invention also establishes a new quality standard for fresh Rehmannia root slices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 Pictures of fresh Rehmannia root slices obtained by different methods; A is the method of boiling in boiling water and then drying; B is the direct drying method; C is the method of drying after high pressure steaming; D is the freeze drying method;

[0037] Figure 2 This is a picture of fresh Rehmannia root slices;

[0038] Figure 3 The figure is a thin layer chromatography identification diagram of fresh Rehmannia slices; wherein A is the reference solution; 1-10 are test solution of 10 batches of fresh Rehmannia slices;

[0039] Figure 4 The figure is a thin layer chromatography identification diagram of fresh Rehmannia slices; wherein A is the reference solution; 1-10 are test solution of 10 batches of fresh Rehmannia slices;

[0040] Figure 5 The figure is a thin layer chromatography identification diagram of fresh Rehmannia slices; wherein A is stachyose; B is raffinose; C is sucrose; HB is the reference solution; 1-10 are the test solution of 10 batches of fresh Rehmannia slices;

[0041] Figure 6 This is the HPLC-ELSD spectrum of 7 sugar components in fresh Rehmannia slices; among them, A is 7 oligosaccharide mixed standards; B is fresh Rehmannia slices; C is fresh Rehmannia (lyophilized); 1-7 are D-fructose, glucose, sucrose, melibiose, raffinose, mannotriose and stachyose, respectively. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0044] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0045] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0046] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0047] Example 1 Preparation of fresh Rehmannia root slices and study on their quality standards

[0048] 1. Design and investigation of preparation method of fresh Rehmannia root slices

[0049] According to the literature reports and the preparation method of fresh Rehmannia root (freeze-dried) in the "Henan Province Traditional Chinese Medicine Piece Processing Specifications", the inventors designed 4 methods for preparing fresh Rehmannia root slices, which are:

[0050] A. Boiling and then drying method: remove impurities from fresh Rehmannia root, wash off the mud and sand, cut into slices (2-4mm) while fresh, boil in boiling water for 5 minutes, then take out and dry at 60℃ with forced air for 24 hours.

[0051] B. Direct drying method: remove impurities from fresh Rehmannia root, wash away mud and sand, cut into slices (2-4mm) while fresh, and then place at 60℃ for 24 hours.

[0052] C. High-pressure steaming followed by drying: remove impurities from fresh Rehmannia root, wash off the mud and sand, slice it while it is still fresh (2-4 mm), then high-pressure steam it at 120°C for 5 minutes, and then air dry it at 60°C for 24 hours.

[0053] D. Freeze-drying method: remove impurities from fresh Rehmannia root, wash away mud and sand, slice it while it is fresh (5-8mm), pre-freeze it at -80℃ for 1h, freeze-dry it for 48h, and take it out.

[0054] The appearance characteristics of the four kinds of decoction pieces prepared by the four methods of AD are as follows: Figure 1As shown. Based on the appearance, the freeze-dried slices have the best appearance, but the freeze-drying cost is too high and industrial preparation is not realistic. Therefore, freeze-dried slices are used as a benchmark and other preparation methods are preferred. Based on the flatness and color of the slices, method A is finally selected, that is, the "boiling and drying method" is used to prepare fresh Rehmannia slices.

[0055] 2. Boiling time inspection

[0056] Fresh Rehmannia slices were prepared according to the "boiling and drying method" selected in "1", and different boiling times were designed (boiling in boiling water for 1, 2, 3, 4, 5, 10, and 20 minutes, respectively). The contents of catalpol and rehmannia glycoside D were determined by the method specified in the pharmacopoeia. The contents of catalpol and rehmannia glycoside D in fresh Rehmannia slices prepared with different boiling times were investigated. The slices with higher contents were considered high-quality slices, and the corresponding methods were preferred. The results are shown in Table 1. The contents of 7 sugar components in fresh Rehmannia slices obtained with different boiling times were determined according to the method in the literature "Qualitative and quantitative analysis of Rehmannia medicinal materials and slices based on sugar spectrum" (Qualitative and quantitative analysis of Rehmannia medicinal materials and slices based on sugar spectrum [J]. Chinese Journal of Experimental Traditional Chinese Medicine, 2024, 30 (18): 136-142.). The results are shown in Table 2.

[0057] Table 1 Contents of catalpol and rehmannia glycoside D in fresh Rehmannia slices prepared by different methods (%)

[0058] serial number FZ1 FZ2 FZ3 FZ4 FZ5 FZ10 FZ20 DG1 Catalpol content / % 2.54 2.35 2.2 1.96 2.33 2.37 1.51 2.03 Rehmannia glutinosin D content / % 0.212 0.171 0.169 0.16 0.166 0.173 0.158 0.206

[0059] Note: FZ1 means boiling water for 1 min, and so on; DG1 means freeze-dried fresh Rehmannia root; the same below

[0060] Table 2 Contents of 7 sugar components in fresh Rehmannia root slices prepared by different methods (%)

[0061] Preparation method D-Fructose glucose sucrose Melibiose Raffinose Mannotriose Stachyose Total content FZ1 0 1.15 5.15 0.327 3.32 0 50.0 59.95 FZ2 0 0.838 5.7 0.277 3.33 0 48.0 58.15 FZ3 0 1.14 5.22 0.278 3.57 0 48.4 58.61 FZ4 0 0.852 4.17 0.335 3.01 0 48.1 56.47 FZ5 0 1.24 5.56 0.385 4.13 0 46.0 57.32 FZ10 0 1.03 5.35 0.376 3.63 0 46.1 56.49 FZ20 0 1.03 4.37 0.271 3.16 0 47.7 56.53 Freeze-drying 0 1.00 3.27 0.311 2.47 0 55.6 62.65

[0062] Note: Lyophilization is the freeze-drying method mentioned above, the same below.

[0063] From the results recorded in Tables 1 and 2, it can be seen that the total content of catalpol, rehmannia glycoside D and seven sugar components in the fresh Rehmannia slices prepared by boiling in boiling water for 1 minute and then drying with forced air at 60°C is the highest, and is closest to the content of freeze-dried fresh Rehmannia slices. Therefore, according to the test results, boiling in boiling water for 1 minute is finally selected as the best preparation method.

[0064] 3. Comparison of different drying temperatures

[0065] Remove impurities from fresh Rehmannia root, wash away the mud and sand, slice it while it is fresh (2-4 mm), boil it in boiling water for 1 min, remove it, and place it in an oven with different temperatures (45°C, 60°C and 80°C) for 24 hours. Determine the content of 7 kinds of sugar components in fresh Rehmannia root slices prepared at different drying temperatures, and select the one with the highest content as the best slice. The drying temperature corresponding to the slice is the optimal drying temperature. The results are shown in Table 3.

[0066] Table 3 Contents of 7 sugar components in fresh Rehmannia slices prepared at different drying temperatures (%)

[0067] Drying temperature D-Fructose glucose sucrose Melibiose Raffinose Mannotriose Stachyose Total content 45℃ 0.00 1.13 6.71 0.00 3.02 0.00 57.88 68.74 60℃ 0.00 1.09 7.58 0.00 3.27 0.00 58.77 70.71 80℃ 0.00 1.16 7.09 0.00 2.87 0.00 58.93 70.04 Freeze-drying 0.00 1.12 7.27 0.00 3.47 0.00 59.24 71.10

[0068] The results showed that 80℃ resulted in a lower content of raffinose, and the content of other sugars was not much different, but the drying temperature was too high and not safe, and the drying time at 45℃ was too long, about 36 hours, while 60℃ drying only required 24 hours, and the sugar content was equivalent to that of the freeze-dried tablets. Therefore, 60℃ was selected as the optimal drying temperature.

[0069] 4. Comparison of fresh Rehmannia slices prepared according to the preferred method and freeze-dried slices

[0070] Three batches of fresh Rehmannia slices were prepared using the preferred method and compared with freeze-dried fresh Rehmannia slices prepared from the same batch of medicinal materials. The results are shown in Table 4.

[0071] Table 4 Comparison of the preferred method for preparing fresh Rehmannia root slices and freeze-drying method

[0072]

[0073] Note: DG is freeze-drying method, FZ1 is the preferred method.

[0074] The results showed that the content of the main components in the fresh Rehmannia slices prepared by the above preferred method (i.e. removing impurities from Rehmannia, washing away mud and sand, slicing while fresh (2-4 mm), boiling in boiling water for 1 min, then taking out, and drying with forced air at 60°C for 24 h) was equivalent to that in the freeze-dried slices, so the method is feasible.

[0075] 5. Determination of the preparation method of fresh Rehmannia slices and preparation of 10 batches of fresh Rehmannia slices

[0076] The final preparation method of fresh Rehmannia slices is: remove impurities from fresh Rehmannia, wash away mud and sand, cut into slices (2-4 mm) while fresh, boil in boiling water for 1 min, remove from the slices, and dry at 60°C for 24 h.

[0077] Preparation of 10 batches of fresh Rehmannia slices: Fresh Rehmannia medicinal materials from different origins were used (batches 1-3 were purchased from Zhaoxian Gucheng Village, Wen County, Jiaozuo City, Henan Province, batches 4-6 were purchased from Huaiyao Base, Wen County, Henan Province, batches 7-8 were purchased from Dafeng Town, Wuzhi County, Jiaozuo City, Henan Province, and batches 9-10 were purchased from Linyi County, Yuncheng City, Shanxi Province), and 10 batches of fresh Rehmannia slices were prepared according to the final preparation method of fresh Rehmannia slices, with an average yield of about 30%.

[0078] 6. Observation of properties of fresh Rehmannia root slices

[0079] Fresh Rehmannia root slices properties Figure 2 As shown: burnt yellow round thin slices, brownish yellow outer skin, slightly wrinkled. Brownish yellow cut surface, light yellowish red cortex, occasionally orange-red oil spots, yellowish white wood. Slight odor, slightly bitter taste.

[0080] 7. Microscopic identification of fresh Rehmannia root slice powder

[0081] Fresh Rehmannia root slices have light yellow powder. The cork cells are light yellow. The parenchyma cells are round and contain round nuclei. The secretory cells are similar to ordinary parenchyma cells and contain orange-yellow or orange-red oil droplets. The diameter of the bordered pit vessels and reticular vessels is about 92μm.

[0082] 8. Thin layer chromatography identification of fresh Rehmannia root slices

[0083] Thin layer chromatography identification 1: Take 2g of each of 10 batches of fresh Rehmannia root slices powder, add 20mL of pure methanol (analytical grade), heat and reflux for 1h, cool, filter, and concentrate the filtrate to 5mL as the test solution. Take another catalpol reference substance, add pure methanol to make a solution containing 0.5mg per 1mL as the reference solution. According to the thin layer chromatography method (General Rule 0502), take 5μL of each of the above two solutions and spot them on the same silica gel G thin layer plate, use chloroform-methanol-water (volume ratio of 14:6:1) as the developing agent, develop, take out, dry, spray with 5mL of anisaldehyde test solution (take 0.5mL of anisaldehyde, add 50mL of acetic acid to dissolve, add 1mL of sulfuric acid, shake well, and the calculated anisaldehyde concentration is about 10.7mg / mL), heat at 105℃ until the spots are clearly colored, and inspect under sunlight. The results are as follows Figure 3 The results show that in the thin layer chromatographic identification diagram, the test sample chromatogram shows spots of the same color at the corresponding positions of the reference sample chromatogram.

[0084] Thin layer chromatography identification 2: Take 1g of each of 10 batches of fresh Rehmannia root slices powder, add 50mL of 80% methanol, ultrasonically treat for 30min, filter, evaporate the filtrate to dryness, add 5mL of water to dissolve the residue, shake and extract 4 times with water-saturated n-butanol, 10mL each time, combine the n-butanol solution, evaporate to dryness, add 2mL of methanol to dissolve the residue as the test solution. Separately take the verbascoside reference substance, add pure methanol to make a solution containing 1mg per 1mL, as the reference substance solution. According to the thin layer chromatography method (General Rule 0502), take 5μL of the above test solution and 2μL of the reference substance solution, respectively, and spot them on the same silica gel G thin layer plate, use ethyl acetate-methanol-formic acid (volume ratio of 16:0.5:2) as the developing solvent, develop, take out, dry, soak the plate with 0.1% 2,2-diphenyl-1-picrylhydrazyl anhydrous ethanol solution, dry, and inspect under sunlight. The results are as follows Figure 4 The results show that in the thin layer chromatographic identification diagram, the test sample chromatogram shows spots of the same color at the corresponding positions of the reference sample chromatogram.

[0085] Thin layer chromatography identification 3: Take 0.2g of each of 10 batches of fresh Rehmannia root slices powder, add 5mL of methanol, ultrasonically treat for 5min, filter, and take the filtrate as the test solution. Separately take stachyose reference, raffinose reference and sucrose reference, add pure methanol to make a solution containing 1mg per 1mL as the reference solution. According to the thin layer chromatography method (General Rule 0502), take 2μL of the above test solution and 10μL of the reference solution, and spot them on the same silica gel G thin layer plate, respectively, with glacial acetic acid-anhydrous formic acid-water-ethyl acetate (volume ratio of 4:5:6:12) as the developing agent, develop, take out, and dry. Spray with 10% sulfuric acid ethanol solution, heat at 120°C until the spots are clearly colored, and inspect under ultraviolet light (365nm). The results are as follows Figure 5 The results show that in the thin layer chromatographic identification diagram, the test sample chromatogram shows spots of the same color at the corresponding positions of the reference sample chromatogram.

[0086] 9. Determination of moisture, total ash and acid-insoluble ash in fresh Rehmannia root slices

[0087] The moisture content of 10 batches of fresh Rehmannia slices was determined according to the second method of Part IV 0832 of the 2020 edition of the "Chinese Pharmacopoeia". The results showed that the moisture content ranged from 7.43% to 10.11%. The results are shown in Table 5.

[0088] The total ash content in 10 batches of fresh Rehmannia slices was determined according to method 2302 of Part IV of the 2020 edition of the Chinese Pharmacopoeia. The results showed that the total ash content ranged from 2.31% to 3.73%. The results are shown in Table 5.

[0089] The acid-insoluble ash content in 10 batches of fresh Rehmannia glutinosa slices was determined according to method 2302 of the General Rules of Part IV of the 2020 edition of the Chinese Pharmacopoeia. The results showed that the acid-insoluble ash content was between 0.102% and 0.268%. The results are shown in Table 5.

[0090] According to the measurement results, it is tentatively determined that the moisture content of the fresh Rehmannia root slices prepared in this embodiment shall not exceed 10.0%, the total ash content shall not exceed 4.0%, and the acid-insoluble ash content shall not exceed 0.30%.

[0091] 10. Determination of water-soluble extracts in fresh Rehmannia root slices

[0092] According to the cold infusion method for the determination of water-soluble extracts under Item 2201 of the General Rules of Part IV of the 2020 edition of the Chinese Pharmacopoeia, the content of water-soluble extracts in 10 batches of fresh Rehmannia glutinosa slices was determined. The results showed that the content of water-soluble extracts ranged from 73.42% to 85.7%. The results are shown in Table 5.

[0093] According to the measurement results, it is tentatively determined that the extract of the fresh Rehmannia root slices prepared in this embodiment shall not be less than 65.0%.

[0094] 11. Determination of catalpol content in fresh Rehmannia root slices

[0095] The content of catalpol was determined according to the method for determining the content of catalpol under Rehmannia glutinosa in the 2020 edition of the Chinese Pharmacopoeia.

[0096] Chromatographic conditions and system suitability test: Octadecylsilane bonded silica gel was used as filler; the chromatographic column was XB-C18; column temperature 30℃; flow rate 1mL / min; injection volume 10μL; methanol-0.1% (V / V) phosphoric acid solution (1:99) as mobile phase; detection wavelength 210nm. The theoretical plate number calculated based on the catalpol peak should not be less than 5000.

[0097] Preparation of reference solution: Take an appropriate amount of catalpol reference, weigh accurately, and add mobile phase to make a solution containing 50 μg per 1 mL.

[0098] Preparation of the test solution: Take 0.8 g of the coarse powder ground from fresh Rehmannia glutinosa slices prepared by the optimized method of this embodiment, accurately weigh it, place it in a stoppered conical flask, accurately add 50 mL of pure methanol, weigh it, heat and reflux to extract for 1.5 h, cool it, weigh it again, make up the lost weight with methanol, shake it well, filter it, accurately measure 10 mL of the filtrate, concentrate it to near dryness, dissolve the residue with the mobile phase, transfer it to a 10 mL volumetric flask, and dilute it to the scale with the mobile phase, shake it well, filter it, and take the filtrate to obtain it.

[0099] Determination method: Accurately pipette 10 μL of reference solution and test solution respectively, inject into liquid chromatograph, and determine.

[0100] Results The catalpol content in 10 batches of fresh Rehmannia glutinosa ranged from 1.99% to 3.65%, with an average content of 2.87%. The results are shown in Table 5.

[0101] According to the test results, the fresh Rehmannia root slices prepared in this example contain catalpol (C 15 H 22 O 10 ) shall not be less than 2.6%.

[0102] 12. Determination of rehmannia glycoside D content in fresh Rehmannia root slices

[0103] The content of rehmannia glutinosa was determined according to the method for determining the content of rehmannia glutinosa glycoside D under the Rehmannia glutinosa item in the 2020 edition of the Chinese Pharmacopoeia.

[0104] Chromatographic conditions and system suitability test: Octadecylsilane bonded silica gel was used as filler; the chromatographic column was XB-C 18 ; Column temperature is 30℃; Flow rate is 1mL / min; Injection volume is 10μL; Methanol-0.1% phosphoric acid solution (5:95) is used as mobile phase; Detection wavelength is 203nm. The theoretical plate number calculated based on the rehmannia glutinosin D peak should not be less than 5000.

[0105] Preparation of reference solution: Take an appropriate amount of Rehmannia glutinosin D reference substance, weigh it accurately, and add 25% methanol to make a solution containing 70 μg per 1 mL.

[0106] Preparation of the test solution: Take 1 g of the coarse powder ground from fresh Rehmannia glutinosa slices prepared by the optimized method of this embodiment, accurately weigh it, place it in a stoppered conical flask, accurately add 25 mL of 25% methanol, weigh it, ultrasonically treat it (power 400 W, frequency 50 kHz) for 1 hour, cool it, weigh it again, make up the lost weight with 25% methanol, shake it well, centrifuge it at high speed for 10 minutes, filter the supernatant, and take the filtrate to obtain the solution.

[0107] Determination method: Accurately pipette 10 μL of reference solution and test solution respectively, inject into liquid chromatograph, and determine.

[0108] Results The content of rehmannoside D in 10 batches of fresh Rehmannia glutinosa ranged from 0.23% to 0.53%, with an average content of 0.30%. The results are shown in Table 5.

[0109] According to the test results, the fresh Rehmannia root slices prepared in this example contain rehmannia glycoside D (C 27 H 42 O 20 ) shall not be less than 0.20%.

[0110] 13. Determination of sugar content in fresh Rehmannia root slices

[0111] The document "Qualitative and quantitative analysis of Rehmannia medicinal materials and decoction pieces based on sugar spectrum" (Qualitative and quantitative analysis of Rehmannia medicinal materials and decoction pieces based on sugar spectrum [J]. Chinese Journal of Experimental Traditional Chinese Medicine, 2024, 30(18): 136-142.) determined the contents of 7 sugar components in fresh Rehmannia decoction pieces obtained by optimized method and fresh Rehmannia decoction pieces obtained by freeze-drying method. The results are as follows Figure 6 shown.

[0112] Chromatographic conditions and system suitability test: tertiary amine alkyl bonded silica gel as filler, COSMOSIL Sugar-D chromatographic column (4.6mm×250mm, 5μm); column temperature 30℃; flow rate 1mL / min; injection volume 10μL; acetonitrile-water (75:25) as mobile phase, evaporative light scattering detector (ELSD) detection, ELSD conditions drift tube temperature 100℃; carrier gas flow rate 2L / min. The theoretical plate number should not be less than 3000 for stachyose.

[0113] Preparation of 7 kinds of oligosaccharide mixed standard substances: accurately weigh 3.07 mg of reference substance D-fructose, 2.52 mg of reference substance glucose, 3.00 mg of reference substance sucrose, 2.52 mg of reference substance melibiose, 2.48 mg of reference substance raffinose, 6.60 mg of reference substance mannotriose and 10.15 mg of reference substance stachyose, place them in the same 10 mL volumetric flask, add 70% (V / V) methanol to dissolve and make up to the scale, shake well, and obtain.

[0114] Preparation of the test solution: Take 0.2 g of the coarse powder ground from the fresh Rehmannia root slices prepared by the optimized method of this embodiment, accurately weigh it, place it in a stoppered conical flask, accurately add 50 mL of 70% methanol, weigh it, ultrasonically treat it (power 400 W, frequency 50 kHz) for 30 min, cool it, weigh it again, make up the lost weight with 70% methanol, shake it well, filter it, and take the filtrate to obtain it.

[0115] Determination method: Accurately pipette 5μL and 20μL of 7 kinds of oligosaccharide mixed standard solutions and 10μL of test solution respectively, inject into high performance liquid chromatography, calculate and determine with the external standard two-point method logarithmic equation, and obtain the result.

[0116] HPLC-ELSD chromatograms of fresh Rehmannia root slices, fresh Rehmannia root freeze-dried slices and mixed reference substances are shown in Figure 6 , the results are shown in Table 5.

[0117] The results showed that the stachyose content in 10 batches of fresh Rehmannia glutinosa ranged from 52.62% to 62.56%, with an average content of 56.59%; the raffinose content ranged from 1.81% to 3.59%, with an average content of 2.76%; the sucrose content ranged from 1.44% to 6.78%, with an average content of 3.89%; the glucose content ranged from 0 to 2.04%, with an average content of 1.28%; the total content of the seven sugars ranged from 59.29% to 67.11%, with an average content of 64.53% (Table 5).

[0118] Table 5 Determination results of various index components of 10 batches of fresh Rehmannia slices / %

[0119]

[0120] Because the stachyose content in the 10 batches of fresh Rehmannia slices accounted for more than 80% of the total sugar content, only the stachyose content was selected to be included in the quality standard. Based on the measurement results, the stachyose content of the fresh Rehmannia slices prepared in this example was tentatively determined to be 1. 27 H 42 O 20 ) shall not be less than 50.0%.

[0121] Embodiment 2 Fresh Rehmannia glutinosa slices quality standard

[0122] 1. Source

[0123] This product is the fresh root of Rehmannia glutinosa Libosch. of the Scrophulariaceae family. It is dug up in autumn, the root head, fibrous roots and mud and sand are removed, and it is used fresh or processed while fresh.

[0124] 2. Preparation

[0125] Remove impurities from fresh Rehmannia root, wash away mud and sand, slice into 2-4 mm slices while fresh, put into boiling water and cook for 1 min, then take out, cool to room temperature, and dry in an oven at 60°C for 24 h.

[0126] 3. Properties

[0127] Fresh Rehmannia root is spindle-shaped or strip-shaped, 8-24cm long and 2-9cm in diameter. The outer skin is thin, light reddish yellow, with curved longitudinal wrinkles, bud scars, horizontal long lenticel-like protrusions and irregular scars. It is fleshy and easy to break. The cross section of the cortex is light yellowish white with orange-red oil spots visible. The wood is yellowish white with ducts arranged radially. It has a faint smell and tastes slightly sweet and slightly bitter.

[0128] Fresh Rehmannia root slices are yellowish white to light yellow round thin slices. The outer skin is grayish yellow or brownish yellow, slightly wrinkled. The cut surface is yellow, the cortex is light yellowish red, with occasional orange-red oil spots, and the wood is white to yellowish white. It has a faint odor and a slightly bitter taste.

[0129] 4. Identification

[0130] (1) The powder of fresh Rehmannia root slices is light yellow. The cork cells are light yellow. The thin-walled cells are round and contain round nuclei. The shape of secretory cells is similar to that of ordinary thin-walled cells, and they contain orange-yellow or orange-red oil droplets. The diameter of the bordered pit ducts and reticular ducts is about 92μm.

[0131] (2) Take 2g of fresh Rehmannia root slice powder, add 20mL of pure methanol, heat and reflux for 1h, cool, filter, and concentrate the filtrate to 5mL as the test solution. Take another catalpol reference substance and add pure methanol to make a solution containing 0.5mg per 1mL as the reference solution. According to the thin layer chromatography method (General Rules 0502 of the Fourth Part of the 2020 Edition of the Chinese Pharmacopoeia), 5μL of each of the above two solutions was taken and spotted on the same silica gel G thin layer plate, using chloroform-methanol-water (volume ratio of 14:6:1) as the developing agent, develop, take out, dry, spray with anisaldehyde test solution, heat at 105°C until the spots are clearly colored, and inspect under sunlight. In the chromatogram of the test sample, spots of the same color appear at the corresponding position of the chromatogram of the reference substance.

[0132] (3) Take 1g of fresh Rehmannia root slice powder, add 50mL of 80% methanol, ultrasonically treat for 30min, filter, evaporate the filtrate, add 5mL of water to the residue to dissolve, shake and extract 4 times with water-saturated n-butanol, 10mL each time, combine the n-butanol solution, evaporate to dryness, and add 2mL of methanol to the residue to dissolve as the test solution. Take another reference substance of verbascoside, add pure methanol to make a solution containing 1mg per 1mL, as the reference solution. According to the thin layer chromatography method (General Rules 0502 of the Fourth Part of the 2020 Edition of the Chinese Pharmacopoeia), take 5μL of the above test solution and 2μL of the reference solution, respectively, and spot them on the same silica gel G thin layer plate, use ethyl acetate-methanol-formic acid (volume ratio of 16:0.5:2) as the developing solvent, develop, take out, dry, soak the plate with 0.1% 2,2-diphenyl-1-picrylhydrazyl anhydrous ethanol solution, dry, and inspect under sunlight. In the test sample chromatogram, a spot of the same color appears at the corresponding position in the reference sample chromatogram.

[0133] (4) Take 0.2g of fresh Rehmannia root slice powder, add 5mL of pure methanol, ultrasonically treat for 5min, filter, and take the filtrate as the test solution. Take stachyose reference, raffinose reference and sucrose reference, add pure methanol to make a mixed solution containing 1mg of each per 1mL, as the reference solution. According to the thin layer chromatography method (General Rule 0502), take 2μL of the above test solution and 10μL of the reference solution, and spot them on the same silica gel G thin layer plate, use glacial acetic acid-anhydrous formic acid-water-ethyl acetate (volume ratio of 4:5:6:12) as the developing agent, develop, take out, and dry. Spray with 10% sulfuric acid ethanol solution, heat at 120℃ until the spots are clearly colored, and examine under ultraviolet light (365nm). In the chromatogram of the test sample, at the corresponding position of the chromatogram of the reference, a spot of the same color fluorescence appears.

[0134] 5. Inspection

[0135] Moisture content of fresh Rehmannia root slices shall not exceed 10.0% (Method 2, Part IV, 0832, 2020 edition of the Chinese Pharmacopoeia).

[0136] Total ash content: Fresh Rehmannia root slices shall not exceed 4.0% (Chinese Pharmacopoeia 2020 Edition, Part IV, General Rules 2302).

[0137] Acid-insoluble ash: The content of fresh Rehmannia root slices shall not exceed 0.30% (General Rules 2302 of Part 4 of the 2020 edition of the Chinese Pharmacopoeia).

[0138] 6. Extract

[0139] The cold infusion method for determination of water-soluble extracts of fresh Rehmannia glutinosa slices (General Rules 2201 of Part IV of the 2020 edition of the Chinese Pharmacopoeia) shall not be less than 65.0%.

[0140] 7. Content determination

[0141] 7.1. Detection of catalpol content in fresh Rehmannia root slices: Determine according to the high performance liquid chromatography method (General Rule 0512).

[0142] Chromatographic conditions and system suitability test: Octadecylsilane bonded silica gel was used as filler; the chromatographic column was XB-C 18 ; Column temperature is 30℃; Flow rate is 1mL / min; Injection volume is 10μL; Methanol-0.1% phosphoric acid solution (1:99) is used as mobile phase; Detection wavelength is 210nm. The theoretical plate number calculated based on the catalpol peak should not be less than 5000.

[0143] Preparation of reference solution: Take an appropriate amount of catalpol reference, weigh accurately, add 2 mL of mobile phase to make a solution containing 50 μg per 1 mL.

[0144] Preparation of test solution: Grind fresh Rehmannia root slices into coarse powder, take about 0.8g, accurately weigh, place in a stoppered conical flask, accurately add 50mL of pure methanol, weigh, heat under reflux to extract 1.5h, cool, weigh again, make up the lost weight with pure methanol, shake well, filter, accurately measure 10mL of the filtrate, concentrate to near dryness, dissolve the residue with the mobile phase methanol-0.1% phosphoric acid solution (1:99), transfer to a 10mL volumetric flask, and dilute to the scale with the mobile phase methanol-0.1% phosphoric acid solution (1:99), shake well, filter, and take the filtrate.

[0145] Determination method: Accurately pipette 10 μL of reference solution and test solution respectively, inject into liquid chromatograph, and determine.

[0146] Catalpol (C 15 H 22 O 10 ) content shall not be less than 2.6%.

[0147] 7.2. Detection of rehmannia glycoside D content in fresh Rehmannia root slices: Determine according to the high performance liquid chromatography method (General Rule 0512).

[0148] Chromatographic conditions and system suitability test: Octadecylsilane bonded silica gel was used as filler; the chromatographic column was XB-C 18 ; Column temperature is 30℃; Flow rate is 1mL / min; Injection volume is 10μL; Methanol-0.1% phosphoric acid solution (5:95) is used as mobile phase; Detection wavelength is 203nm. The theoretical plate number calculated based on the rehmannia glutinosin D peak should not be less than 5000.

[0149] Preparation of reference solution: Take an appropriate amount of Rehmannia glutinosin D reference substance, weigh it accurately, and add 25% methanol to make a solution containing 70 μg per 1 mL.

[0150] Preparation of test solution: Grind fresh Rehmannia root slices into coarse powder, take about 1g, weigh accurately, put it in a stoppered conical flask, accurately add 25mL of 25% methanol, weigh the weight, ultrasonically treat (power 400W, frequency 50kHz) for 1h, cool, weigh again, make up the lost weight with 25% methanol, shake well, centrifuge at high speed for 10min, filter the supernatant, and take the filtrate to obtain the solution.

[0151] Determination method: Accurately pipette 10 μL of reference solution and test solution respectively, inject into liquid chromatograph, and determine.

[0152] Rehmannia glutinosa glycoside D (C 27 H 42 O 20 ) content shall not be less than 0.20%.

[0153] 7.3. Detection of stachyose content in fresh Rehmannia slices: Determine according to the high performance liquid chromatography method (General Rule 0512).

[0154] Chromatographic conditions and system suitability test: tertiary amine alkyl bonded silica gel as filler, COSMOSIL Sugar-D chromatographic column (column length 25 cm, inner diameter 4.6 mm, particle size 5 μm); column temperature 30°C; flow rate 1 mL / min; injection volume 10 μL; acetonitrile-water (75:25) as mobile phase; evaporative light scattering detector (ELSD) detection, ELSD conditions are drift tube temperature 100°C; carrier gas flow rate 2 L / min; the number of theoretical plates calculated based on the stachyose peak should not be less than 3000.

[0155] Preparation of reference solution: Take an appropriate amount of stachyose reference substance, weigh accurately, and add 70% methanol to make a solution containing 1 mg per 1 mL.

[0156] Preparation of test solution: Grind fresh Rehmannia root slices into coarse powder, take about 0.2 g, accurately weigh, place in a stoppered conical flask, accurately add 50 mL of 70% methanol, weigh the weight, ultrasonically treat (power 400 W, frequency 50 kHz) for 30 min, cool, weigh again, make up the lost weight with 70% methanol, shake well, filter, and take the filtrate.

[0157] Determination method: Accurately pipette 5μL and 20μL of reference solution and 10μL of test solution respectively, inject into liquid chromatograph, determine, and calculate with external standard two-point method logarithmic equation to obtain the result.

[0158] Stachyose in fresh Rehmannia root slices (C 27 H 42 O 20 ) content shall not be less than 50.0%.

[0159] 8. Nature and flavor and meridians

[0160] Sweet, bitter, cold. Acts on the heart, liver and kidney meridians.

[0161] 9. Function and indications

[0162] It can clear away heat, promote the production of body fluid, cool blood and stop bleeding. It is used for heat diseases that damage the yin, red tongue and thirst, fever and rashes, hematemesis, epistaxis and sore throat.

[0163] 10. Dosage and Usage

[0164] 12-30g fresh Rehmannia root; 3-10g fresh Rehmannia root slices.

[0165] 11. Notes

[0166] Use with caution in patients with weak spleen and stomach.

[0167] 12. Storage

[0168] Place in a cool, dry place to prevent mildew and moth damage.

[0169] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing fresh Rehmannia root slices, characterized in that: The method comprises the steps of successively boiling and drying fresh Rehmannia root slices to obtain the fresh Rehmannia root slices; The cooking time is 1-10 min.

2. The preparation method according to claim 1, characterized in that: The drying temperature is 45°C-80°C and the drying time is 24 hours.

3. The preparation method according to claim 1, characterized in that: The drying method is air-blast drying.

4. The preparation method according to claim 1, characterized in that: The thickness of the fresh Rehmannia root slice is 2-4 mm.

5. A fresh Rehmannia root slice prepared by the method according to any one of claims 1 to 4.

6. A quality control method for fresh Rehmannia root slices according to claim 5, characterized in that: include: (1) observing the shape of the fresh Rehmannia root slices; (2) performing powder microscopic identification on the fresh Rehmannia root slices; (3) Testing the moisture content, total ash content, acid-insoluble ash content and extract of the fresh Rehmannia root slices; the moisture content of the fresh Rehmannia root slices shall not exceed 10.0%, the total ash content shall not exceed 4.0%, the acid-insoluble ash content shall not exceed 0.30%, and the extract content shall not be less than 65.0%; (4) performing thin layer chromatography identification on the fresh Rehmannia root slices; (5) The contents of catalpol, rehmannia glutinosa D and stachyose in the fresh Rehmannia glutinosa slices are detected by high performance liquid chromatography; the content of catalpol in the fresh Rehmannia glutinosa slices shall not be less than 2.6%, the content of rehmannia glutinosa D shall not be less than 0.20%, and the content of stachyose shall not be less than 50.0%.

7. The quality control method according to claim 6, characterized in that: The thin layer chromatography identification includes method 1, method 2 and method 3; The method 1 comprises the steps of taking a test solution and a catalpol reference solution and spotting them on a silica gel G thin layer plate, using a mixed solution of chloroform, methanol and water as a developing agent, developing, spraying anisaldehyde test solution, heating, and observing under sunlight; the preparation method of the test solution comprises the steps of mixing a sample powder to be tested with an ethanol solution, heating and refluxing, filtering and concentrating in sequence to obtain the test solution; the preparation method of the catalpol reference solution comprises the steps of mixing a catalpol reference with methanol to obtain the catalpol reference solution; the concentration of catalpol in the catalpol reference solution is 0.5 mg / mL; The method 2 comprises the steps of taking a test solution and a verbascoside reference solution and spotting them on a silica gel G thin layer plate, using a mixed solution of ethyl acetate, methanol and formic acid as a developing agent, developing, immersing the plate with a 0.1% 2,2-diphenyl-1-picrylhydrazyl anhydrous ethanol solution, drying, and observing under sunlight; the preparation method of the test solution comprises the steps of mixing a sample powder to be tested with an ethanol solution, performing ultrasonic treatment and n-butanol extraction in sequence, to obtain the test solution; the preparation method of the verbascoside reference solution comprises the steps of mixing a verbascoside reference with methanol, to obtain the verbascoside reference solution; the concentration of verbascoside in the verbascoside reference solution is 1 mg / mL; The method 3 comprises the steps of spotting a test solution and a reference solution containing stachyose, raffinose and sucrose on a silica gel G thin layer plate, developing with a mixed solution of glacial acetic acid, anhydrous formic acid, water and ethyl acetate as a developing agent, spraying with 10% sulfuric acid ethanol solution, heating, and observing under a 365nm ultraviolet lamp; the preparation method of the test solution comprises the steps of mixing the sample powder to be tested with the ethanol solution, performing ultrasonic treatment and filtering in sequence to obtain the test solution; the preparation method of the reference solution containing stachyose, raffinose and sucrose comprises the step of mixing a stachyose reference substance, a raffinose reference substance and a sucrose reference substance with methanol to obtain the reference solution containing stachyose, raffinose and sucrose; the concentration of stachyose in the reference solution containing stachyose, raffinose and sucrose is 1 mg / mL, the concentration of raffinose is 1 mg / mL, and the concentration of sucrose is 1 mg / mL.

8. The quality control method according to claim 7, characterized in that: In the method 1, the volume ratio of chloroform, methanol and water in the developing solvent is 14:6:1; the heating temperature is 105° C.; the concentration of anisaldehyde in the anisaldehyde test solution is 10.7 mg / mL; the mass volume ratio of the sample powder to be tested and the ethanol solution is 1 g:20 mL; In the method 2, the volume ratio of ethyl acetate, methanol and formic acid in the developing solvent is 16:0.5:2; the concentration of 2,2-diphenyl-1-picrylhydrazyl in the 2,2-diphenyl-1-picrylhydrazyl anhydrous ethanol solution is 0.1%; the mass volume ratio of the sample powder to be tested and the ethanol solution is 1g:50mL; In method 3, the volume ratio of glacial acetic acid, anhydrous formic acid, water and ethyl acetate in the developing agent is 4:5:6:12; the concentration of sulfuric acid in the sulfuric acid ethanol solution is 10%; and the mass volume ratio of the sample powder to be tested and the ethanol solution is 1g:25mL.

9. The quality control method according to claim 6, characterized in that: The thin layer chromatography identification includes method a, method b and method c; The method a comprises the steps of taking a catalpol reference solution and a test solution, injecting them into a liquid chromatograph, and performing chromatographic detection; the method for preparing the catalpol reference solution comprises the step of mixing the catalpol reference solution and methanol to obtain the catalpol reference solution; the concentration of catalpol in the catalpol reference solution is 50 μg / mL; the method for preparing the test solution comprises the step of mixing the sample powder to be tested with methanol, and sequentially performing heating reflux extraction, filtering, concentrating, dissolving and filtering to obtain the test solution; The method b comprises the steps of taking a rehmannia glycoside D reference solution and a test solution, injecting them into a liquid chromatograph, and performing chromatographic detection; the preparation method of the rehmannia glycoside D reference solution comprises the step of mixing the catalpol reference solution and methanol to obtain the rehmannia glycoside D reference solution; the concentration of rehmannia glycoside D in the rehmannia glycoside D reference solution is 70 μg / mL; the preparation method of the test solution comprises the step of mixing the sample powder to be tested and methanol, and sequentially performing ultrasonic treatment, centrifugation and filtration to obtain the test solution; The method c comprises the steps of aspirating a stachyose reference solution and a test solution, injecting them into a liquid chromatograph, and performing chromatographic detection; the preparation method of the stachyose reference solution comprises the step of mixing the stachyose reference solution and methanol to obtain the stachyose reference solution; the concentration of catalpol in the stachyose reference solution is 1 mg / mL; the preparation method of the test solution comprises the step of mixing the sample powder to be tested and methanol, and performing ultrasonic treatment and filtering in sequence to obtain the test solution.

10. The quality control method according to claim 9, characterized in that: In the method a, the chromatographic detection conditions are: using octadecylsilane bonded silica gel as a filler; the chromatographic column is XB-C 18 ; Column temperature was 30°C; Flow rate was 1 mL / min; Injection volume was 10 μL; Eluent was methanol-0.1% phosphoric acid solution; Detection wavelength was 210 nm; In the method b, the chromatographic detection conditions are: using octadecylsilane bonded silica gel as a filler; the chromatographic column is XB-C 18 ; Column temperature was 30°C; Flow rate was 1 mL / min; Injection volume was 10 μL; Eluent was methanol-0.1% phosphoric acid solution; Detection wavelength was 203 nm; In the method c, the conditions for the chromatographic detection are: tertiary amine alkyl bonded silica gel as the filler; the chromatographic column is a COSMOSIL Sugar-D chromatographic column; the column temperature is 30°C; the flow rate is 1 mL / min; the injection volume is 10 μL; and acetonitrile-water is used as the mobile phase for elution.

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