A method for extracting 6,7-dihydroxy-2,4-dimethoxyphenanthrene

Abstract

This invention belongs to the field of chemical analysis and relates to the extraction of 6,7-dihydroxy-2,4-dimethoxyphenanthrene, specifically a method for extracting high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene. This invention, by improving extraction efficiency, simplifying purification steps, increasing product purity, and reducing preparation costs, helps promote the application development and market application of this compound, and also contributes to the sustainable development of related industries. This invention fully utilizes the abundant resources of yam and its by-products, turning waste yam by-products into valuable resources. This not only extends the yam industry chain and increases added value, but also makes full use of resources, resulting in significant economic and social benefits. This invention also has significant advantages in improving separation efficiency, reducing environmental pollution, simplifying operations, increasing yield, and fully utilizing resources, and is expected to be widely applied and promoted in the field of yam compound extraction.

Description

Technical Field

[0001] This invention belongs to the field of chemical analysis and relates to the extraction of 6,7-dihydroxy-2,4-dimethoxyphenanthrene, specifically a method for extracting high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene. Background Technology

[0002] Yam ( Dioscorea opposita Yam (Dioscorea opposita) is the rhizome of a plant belonging to the genus Dioscorea in the family Dioscoreaceae. It is widely cultivated and used for both food and medicinal purposes. It is one of my country's traditional medicinal and edible plant resources, with a long history and rich nutritional value. Yam is rich in amino acids, organic acids, sugars, and other nutrients, as well as bioactive secondary metabolites such as saponins, flavonoids, and alkaloids. Therefore, yam is widely used in traditional Chinese medicine and is believed to have effects such as enhancing immunity, strengthening the spleen and stopping diarrhea, and tonifying the lungs and kidneys. With in-depth research into natural plant resources, attention is increasingly focused on the bioactive compounds in yam and its byproducts.

[0003] Compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene is a natural product extracted from plants such as yam, with the molecular formula C. 16 H 14 O4, with a molecular weight of 270.28 g / mol and CAS number 42050-16-8, has the following molecular structure:

[0004]

[0005] It possesses a variety of biological activities, including anti-inflammatory, antioxidant, hypoglycemic, antifungal, and anticoagulant effects, and has broad application prospects.

[0006] In the field of plant extraction, studies have shown that 6,7-dihydroxy-2,4-dimethoxyphenanthrene is abundant in plants such as yam, yam beans, yam peel, and yam stems and leaves. The reagents and equipment used in the separation and preparation technique of 6,7-dihydroxy-2,4-dimethoxyphenanthrene reported by Li et al. mainly included hexane, ethyl acetate, methanol solution, chloroform, rotary evaporator, high-performance liquid chromatography (HPLC) silica gel column, and thin-layer chromatography. The article mentioned the isolation of 35.1 mg of this compound from 5 kg of mature Chinese yam. The separation process was as follows: the yam was peeled, freeze-dried, and ground. The powder was extracted sequentially with hexane, ethyl acetate, and methanol (3 × 1 L, 2 h). The ethyl acetate extract was obtained by evaporating the ethyl acetate extract under reduced pressure using a rotary evaporator. The ethyl acetate extract was then chromatographically separated on a medium-pressure HPLC silica gel column using CHCl3-MeOH under gradient conditions (20:1, 10:1, 4:1, and 1:1, v / v). Thin-layer chromatography was used for color development, and similar fractions were combined to obtain six fractions. Part 5 was purified by preparative thin-layer chromatography (CHCl3-isopropanol, 15:1, twice, v / v) to obtain 35.1 mg of compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene, with a yield of only 0.000702%. (Li, Q. , Zhang, CR , Dissanayake, AA , Gao, QY , & Nair, MG Phenanthrenes in chinese yampeel exhibit antiinflammatory activity, as shown by strong in vitro cyclooxygenase enzyme inhibition. Natural Product Communications, 2016, 11(9), 1313-1316;); The reagents and equipment used in the separation and preparation technology of 6,7-dihydroxy-2,4-dimethoxyphenanthrene reported by Mitsuo et al. mainly include acetone, methanol, ethyl acetate, silica gel chromatography, and ultraviolet spectrophotometer; 4.6 kg of dried yam tuber slices were extracted with acetone and methanol successively to obtain acetone and methanol extracts. The methanol extract was extracted with ethyl acetate to obtain the ethyl acetate-soluble fraction, which was further purified by silica gel chromatography. The eluent was evaporated to obtain a brown oil, which was then separated into five fractions by chloroform-methanol (1:9) chromatography on a Sephadex LH-20 (5×350 mm) spectrometer.The third and fourth fractions, after evaporation, yielded oily residues, R1 and R2, respectively. R2 showed three fluorescent spots at UV 366 nm. These were separated into eight fractions by silica gel column chromatography with dichloromethane-methanol (49:1). The second and sixth fractions showed single spots on TLC. Concentration yielded the crystalline compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene. The yield of the compound using this method was 0.000435%. (Mitsuo, Takasugi, and, Shinji, Kawashima, & and, et al. Antifungal compounds from dioscorea batatas inoculated with pseudomonascichorii. Phytochemistry, 1987). 26 (2), 371-375.)); Due to the complex process and low extraction efficiency, the existing methods have high production costs, which limits the feasibility of this compound in large-scale commercial applications. The compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene sells for tens of thousands of yuan for 5 mg. The two reported separation and preparation techniques have very low extraction yields, at 0.000702% and 0.000435%, respectively.

[0007] The above separation and preparation methods are extremely complex and cumbersome. The separation process involves the use of toxic and harmful reagents such as hexane, ethyl acetate, methanol, chloroform, dichloromethane, and isopropanol. Furthermore, it repeatedly employs time-consuming and labor-intensive separation techniques such as preparative thin-layer chromatography and medium-pressure liquid chromatography with silica gel. These techniques are only suitable for laboratory-scale production and cannot be used for industrial applications, resulting in low yields and high prices of 6,7-dihydroxy-2,4-dimethoxyphenanthrene, thus limiting research and applications related to 6,7-dihydroxy-2,4-dimethoxyphenanthrene. Therefore, there is an urgent need to develop an efficient, simple, and low-cost separation and preparation method to produce high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention proposes a method for extracting high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene. The extraction and separation method of this application yields a significantly higher amount of 6,7-dihydroxy-2,4-dimethoxyphenanthrene, exceeding 28 times that of existing technologies, with a purity of 99.1%. This method overcomes the shortcomings of existing technologies, achieving efficient and simple separation and preparation of 6,7-dihydroxy-2,4-dimethoxyphenanthrene while ensuring a high level of purity. This provides technical support for the further industrial production, scientific research, and clinical application of 6,7-dihydroxy-2,4-dimethoxyphenanthrene.

[0009] The technical solution of this invention is implemented as follows:

[0010] A method for extracting high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene includes the following steps:

[0011] Step 1: Using plants rich in 6,7-dihydroxy-2,4-dimethoxyphenanthrene and their byproducts as raw materials, pulverize and dry them to obtain a powder rich in 6,7-dihydroxy-2,4-dimethoxyphenanthrene and their byproducts.

[0012] Step 2: Extract the powder from Step 1 in stages using a certain proportion of extraction solvent under hot reflux conditions, combine the extracts, and obtain the extract.

[0013] Step 3: Dilute the extract obtained in Step 2 and place it in a container of appropriate volume. Add the specific macroporous adsorption resin to the container in proportion and let it stand for a certain period of time for adsorption. Then, remove the adsorbed extract and add a specific volume fraction of solution for desorption. After shaking for desorption, obtain the desorbed solution. Concentrate all the desorbed solutions under pressure to dryness to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene.

[0014] Step 4: The crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene from Step 3 is recrystallized using a solution of a certain proportion to obtain high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene.

[0015] Preferably, the plants and their appendages rich in 6,7-dihydroxy-2,4-dimethoxyphenanthrene described in step 1 are limited to, but not limited to, yam, yam beans, yam peel, yam stems and leaves, etc.

[0016] Preferably, the ratio of raw material to extraction solvent in the hot reflux extraction in step 2 (referred to as the material-to-solid ratio) is 1:5-15, and the most preferred material-to-solid ratio is 1:12.

[0017] The extraction solvent mentioned above is one or a combination of methanol, ethanol, propanol, and acetone, with ethanol being the most preferred.

[0018] The extraction solvent is at least one of an aqueous ethanol solution with a volume fraction of 10-95% and pure water, with 90% aqueous ethanol solution being the most preferred; the extraction temperature is 40-100℃, with 60℃ being the most preferred.

[0019] Preferably, the extract in step 3 is diluted to a volume ratio of 30%-80% aqueous extract solution, most preferably 50%. The desorption solution is a volume ratio of 60%-100% aqueous ethanol solution, most preferably 70%.

[0020] Furthermore, the macroporous adsorption resin is one or more of HP20, HPD100, D301, AB-8 and SP850, with HP20 being the most preferred.

[0021] Furthermore, the adsorption time is 0.5-6 hours, with 2 hours being the most preferred. The desorption time is 0.5-3 hours, with 1 hour being the most preferred.

[0022] Preferably, the solvent used for recrystallization in step 4 is at least one of acetone, diethyl ether, ethanol and pure water, and more preferably a diethyl ether-ethanol solution with a volume ratio of 1:5.

[0023] The present invention has the following beneficial effects:

[0024] 1. Improved Extraction Efficiency: This invention aims to improve the extraction efficiency of the target compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene. By optimizing the extraction process steps and conditions, this invention can more effectively extract the target compound from yam and its appendages, improving extraction efficiency, achieving higher yields, and reducing resource waste.

[0025] 2. Simplified Process Steps: This invention aims to simplify the preparation method and reduce cumbersome process steps. By optimizing the purification process, the complexity and risk of the preparation process are reduced, and production efficiency is improved.

[0026] 3. Reduced Costs: This invention utilizes efficient extraction and purification processes, reducing the amount of raw materials and equipment used, thereby lowering production costs. Low-cost preparation will help improve the feasibility of this compound in commercial applications and promote its market adoption.

[0027] 4. Environmental friendliness: This invention does not use toxic or harmful chemical reagents such as n-hexane, ethyl acetate, methanol, chloroform, and dichloromethane, thereby reducing the risk of environmental pollution. Environmental friendliness is an important consideration in this invention, contributing to the promotion of sustainable development and green manufacturing.

[0028] 5. Achieving Industrialized Production: This invention aims to provide a preparation method suitable for industrialized production. By simplifying process steps, reducing costs, and increasing yield, the preparation method of this invention better meets the needs of large-scale industrial production and is expected to achieve the industrialized preparation of compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene.

[0029] 6. This invention aims to overcome many shortcomings of existing technologies by optimizing the extraction and purification process to improve the extraction efficiency and purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene. This invention prepares high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene using a method that features high yield, fewer process steps, simple operation, and low cost, achieving a compound purity of over 98%. Compared to existing processes, this method for preparing the active compound offers higher yield, simpler operation, and lower cost, making it easier to implement for industrial production. This invention extends the yam industry chain, increases its added value, and enables comprehensive development and utilization of yam resources. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The structural formula is 6,7-dihydroxy-2,4-dimethoxyphenanthrene.

[0032] Figure 2 The 1H-NMR spectrum of 6,7-dihydroxy-2,4-dimethoxyphenanthrene is shown.

[0033] Figure 3 The 13C-NMR spectrum of 6,7-dihydroxy-2,4-dimethoxyphenanthrene is shown.

[0034] Figure 4 The DEPT spectrum of 6,7-dihydroxy-2,4-dimethoxyphenanthrene is shown. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0036] The extraction method for high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene of this embodiment includes the following steps:

[0037] (1) Crush 1 kg of dried yam beans and pass them through an 80-mesh sieve. Add 10 times the volume of the material to a 95% ethanol-water solution and extract twice by hot reflux at 60°C for two hours each time. Combine the two filtrates.

[0038] (2) Dilute the obtained extract with water to a volume fraction of 50%, then filter it through a 400-mesh filter cloth to obtain the loading solution; add the activated HP20 macroporous rubber resin to the loading solution, discard the remaining solution after adsorption saturation, rinse twice with the same concentration of ethanol-water solution, absorb the solution inside, and concentrate under pressure to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene;

[0039] (3) Add 90% ethanol-water solution to crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene for desorption. Recrystallize the desorbed solution repeatedly to finally obtain 199.66 mg of high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene with a yield of 0.019966%.

[0040] The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was determined by ultra-high performance liquid chromatography (UHPLC). The chromatographic conditions were as follows: Shimadzu GIST C18-AQ silica gel HPLC column (4.6 mm × 250 mm, 5 µm), UV detection wavelength 261 nm, column temperature 40 °C, and mobile phase isocratic elution with water:methanol (30:70). The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was 99.1%. Example 2

[0041] The extraction method for high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene of this embodiment includes the following steps:

[0042] (1) Take 1 kg of dried yam peel, crush it, and pass it through an 80-mesh sieve. Add 6 times the volume of the material to a 70% methanol-water solution, and extract twice by hot reflux at 70°C for two hours each time. Combine the two filtrates.

[0043] (2) Dilute the obtained extract with water to a volume fraction of 30%, then filter it through a 400-mesh filter cloth to obtain the loading solution; add the activated HPD100 macroporous rubber resin to the loading solution, discard the remaining solution after adsorption saturation, rinse twice with the same concentration of ethanol-water solution, absorb the solution inside, and concentrate under pressure to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene;

[0044] (3) Add 60% ethanol-water solution to crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene for desorption. Recrystallize the desorbed solution repeatedly to finally obtain 486.22 mg of high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene, with a yield of 0.048622%.

[0045] The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was determined by ultra-high performance liquid chromatography (UHPLC). The chromatographic conditions were as follows: Shimadzu GIST C18-AQ silica gel HPLC column (4.6 mm × 250 mm, 5 µm), UV detection wavelength 261 nm, column temperature 40 °C, and mobile phase isocratic elution with water:methanol (30:70). The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was 98.2%. Example 3

[0046] The extraction method for high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene of this embodiment includes the following steps:

[0047] (1) Take 1 kg of dried yam stems and leaves, crush them, and pass them through an 80-mesh sieve. Add 15 times the volume of the material to a 95% propanol-water solution, and extract twice by hot reflux at 65°C for two hours each time. Combine the two filtrates.

[0048] (2) Dilute the obtained extract with water to an extract with a volume fraction of 80%, and then filter it through a 400-mesh filter cloth to obtain the loading solution; add the activated D301 macroporous rubber resin to the loading solution, discard the remaining solution after adsorption saturation, rinse twice with the same concentration of ethanol-water solution, absorb the solution inside, and concentrate under pressure to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene;

[0049] (3) Add ethanol solution to crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene for desorption, and recrystallize the desorbed solution repeatedly to finally obtain 13.58 mg of high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene with a yield of 0.001358%.

[0050] The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was determined by ultra-high performance liquid chromatography (UHPLC). The chromatographic conditions were as follows: Shimadzu GIST C18-AQ silica gel HPLC column (4.6 mm × 250 mm, 5 µm), UV detection wavelength 261 nm, column temperature 40 °C, and mobile phase isocratic elution with water:methanol (30:70). The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was 98.01%. Example 4

[0051] The extraction method for high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene of this embodiment includes the following steps:

[0052] (1) After drying, 1 kg of yam is crushed and passed through an 80-mesh sieve. Add 8 times the volume of 80% acetone-water solution to the material and extract twice by hot reflux at 65°C for two hours each time. Combine the two filtrates.

[0053] (2) Dilute the obtained extract with water to a volume fraction of 60%, then filter it through a 400-mesh filter cloth to obtain the loading solution; add the activated SP850 macroporous rubber resin to the loading solution, discard the remaining solution after adsorption saturation, rinse twice with the same concentration of ethanol-water solution, absorb the solution inside, and concentrate under pressure to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene;

[0054] (3) Add 70% ethanol-water solution to crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene for desorption. Recrystallize the desorbed solution repeatedly to finally obtain 103.83 mg of high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene with a yield of 0.010383%.

[0055] The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was determined by ultra-high performance liquid chromatography (UHPLC). The chromatographic conditions were as follows: Shimadzu GIST C18-AQ silica gel HPLC column (4.6 mm × 250 mm, 5 µm), UV detection wavelength 261 nm, column temperature 40 °C, and mobile phase isocratic elution with water:methanol (30:70). The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was 98.5%. Example 5

[0056] The extraction method for high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene of this embodiment includes the following steps:

[0057] (1) Take 1 kg of dried yam and yam beans, crush them, and pass them through an 80-mesh sieve. Add 12 times the volume of the material to a 90% ethanol-water solution, and extract twice by hot reflux at 60°C for two hours each time. Combine the two filtrates.

[0058] (2) Dilute the obtained extract with water to a volume fraction of 60%, then filter it through a 400-mesh filter cloth to obtain the loading solution; add the activated SP850 macroporous rubber resin to the loading solution, discard the remaining solution after adsorption saturation, rinse twice with the same concentration of ethanol-water solution, absorb the solution inside, and concentrate under pressure to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene;

[0059] (3) Add 70% ethanol-water solution to crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene for desorption. Recrystallize the desorbed solution repeatedly to finally obtain 159.21 mg of high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene with a yield of 0.015921%.

[0060] The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was determined by ultra-high performance liquid chromatography (UHPLC). The chromatographic conditions were as follows: Shimadzu GIST C18-AQ silica gel HPLC column (4.6 mm × 250 mm, 5 µm), UV detection wavelength 261 nm, column temperature 40 °C, and mobile phase isocratic elution with water:methanol (30:70). The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was 98.3%. Example 6

[0061] The extraction method for high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene of this embodiment includes the following steps:

[0062] (1) Crush 1 kg of dried yam beans and pass them through an 80-mesh sieve. Add 13 times the volume of the material to a 90% ethanol-water solution and extract twice by hot reflux at 65°C for two hours each time. Combine the two filtrates.

[0063] (2) Dilute the obtained extract with water to a volume fraction of 70%, then filter it through a 400-mesh filter cloth to obtain the loading solution; add the activated AB-8 type macroporous rubber resin to the loading solution, discard the remaining solution after adsorption saturation, rinse twice with the same concentration of ethanol-water solution, absorb the solution inside, and concentrate under pressure to obtain crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene;

[0064] (3) Add 70% ethanol-water solution to crude 6,7-dihydroxy-2,4-dimethoxyphenanthrene for desorption. Recrystallize the desorbed solution repeatedly to finally obtain 186.06 mg of high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene with a yield of 0.018606%.

[0065] The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was determined by ultra-high performance liquid chromatography (UHPLC). The chromatographic conditions were as follows: Shimadzu GIST C18-AQ silica gel HPLC column (4.6 mm × 250 mm, 5 µm), UV detection wavelength 261 nm, column temperature 40 °C, and mobile phase isocratic elution with water:methanol (30:70). The purity of 6,7-dihydroxy-2,4-dimethoxyphenanthrene was 98.1%.

[0066] Implementation effect

[0067] Identification of 6,7-dihydroxy-2,4-dimethoxyphenanthrene:

[0068] The monomeric compound 6,7-dihydroxy-2,4-dimethoxyphenanthrene obtained in this application is a milky white powder. Its proton, carbon, and DEPT spectra obtained using 600MHz nuclear magnetic resonance (deuterated methanol) are shown below. Figure 2-4 As shown, its structure was identified, and the results are as follows:

[0069] In the 1H NMR spectrum, the singlet at chemical shift 8.98 ppm represents the hydrogen proton signal at position 5; the doublets at 7.48 ppm and 7.42 ppm represent the hydrogen proton signals at positions 9 and 10, respectively; the singlet at 7.15 ppm represents the hydrogen proton signal at position 8; and 6.89 ppm and 6.74 ppm correspond to H-1 and H-3, respectively. The proton signals for the two methoxy groups are singlets at 4.08 ppm and 3.91 ppm, respectively. (See Appendix) Figure 2 .

[0070] In the carbon NMR spectroscopy data, a total of 16 carbon proton signals were observed. Two carbon proton peaks at 54.4 ppm and 54.6 ppm were located at the high field, corresponding to the two methoxy groups on the phenanthrene ring. The other 14 carbon proton peaks were distributed at the low field. The peaks at 159.2 ppm, 157.4 ppm, 145.2 ppm, and 144.1 ppm corresponded to the carbon proton peaks on the hydroxyl and methoxy-substituted quaternary carbons, respectively. The peaks at 134.6 ppm, 126.9 ppm, 124.7 ppm, and 115.2 ppm corresponded to the proton signals of the remaining four quaternary peaks on the phenanthrene ring, respectively. The peaks at 127.1 ppm, 123.9 ppm, 112.3 ppm, 111.3 ppm, 101.0 ppm, and 98.3 ppm corresponded to the proton signals of the six tertiary carbons on the phenanthrene ring, respectively. (See Appendix) Figure 3 .

[0071] The DEPT NMR spectroscopy data also confirmed that the peaks at 54.4 ppm and 54.6 ppm are methoxy peaks, and the peaks at 126.9 ppm, 123.9 ppm, 112.3 ppm, 111.3 ppm, 101.0 ppm, and 98.3 ppm are CH peaks (see Appendix). Figure 4 .

[0072] As shown above, the extraction method of this application yields 45 times higher and with higher purity compared to existing extraction methods; this invention significantly increases the application value of yam byproducts. By efficiently preparing high-purity 6,7-dihydroxy-2,4-dimethoxyphenanthrene, yam byproducts are no longer considered byproducts but have become a resource with significant commercial value. This invention fully utilizes the abundant, often overlooked resources of yam beans, yam peels, and yam stems and leaves, turning waste materials into valuable resources. This not only extends the yam industry chain and increases added value but also fully utilizes resources, resulting in significant economic and social benefits. This invention also has obvious advantages in improving separation efficiency, reducing environmental pollution, simplifying operations, increasing yield, and fully utilizing resources, and is expected to be widely applied and promoted in the field of yam compound extraction.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for extracting 6,7-dihydroxy-2,4-dimethoxyphenanthrene, characterized in that, This can be achieved through the following steps: (1) Using plants rich in 6,7-dihydroxy-2,4-dimethoxyphenanthrene or their appendages as raw materials, after pulverizing and drying, solvent is added to the obtained raw material powder and a hot reflux reaction is carried out to obtain an extract; (2) After diluting the extract, add it to the macroporous adsorption resin, let it stand for adsorption, recover the extract, and then desorb it to obtain the desorbed solution. After pressure concentration, 6,7-dihydroxy-2,4-dimethoxyphenanthrene crude product is obtained. (3) 6,7-Dihydroxy-2,4-Dimethoxyphenanthrene crude product was recrystallized to obtain 6,7-dihydroxy-2,4-dimethoxyphenanthrene; the purity of the 6,7-dihydroxy-2,4-dimethoxyphenanthrene was >98%; The raw materials mentioned in step (1) are one or more combinations of yam, yam beans, yam peel, yam stems and yam leaves; The solvent mentioned in step (1) is one or a combination of methanol, ethanol, propanol and acetone; The macroporous adsorption resin mentioned in step (2) is HPD100; The solvent used for recrystallization in step (3) is at least one of acetone, diethyl ether, ethanol and pure water.

2. The extraction method for 6,7-dihydroxy-2,4-dimethoxyphenanthrene according to claim 1, characterized in that, The solvent used in step (1) is an aqueous ethanol solution with a volume fraction of 10%-95%.

3. The extraction method for 6,7-dihydroxy-2,4-dimethoxyphenanthrene according to claim 1, characterized in that, The volume ratio of the raw material powder to the solvent in step (1) is 1:5-15.

4. The extraction method for 6,7-dihydroxy-2,4-dimethoxyphenanthrene according to claim 1, characterized in that, The volume fraction of the extract after dilution in step (2) is 30%-80%.

5. The extraction method for 6,7-dihydroxy-2,4-dimethoxyphenanthrene according to claim 1, characterized in that, The desorption solution used is an ethanol-water solution with a volume fraction of 60%-100%.

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