Green method for preparing bakuchiol and application of bakuchiol in oxidation resistance

Abstract

The invention discloses a green method for preparing bakuchiol and application of bakuchiol in oxidation resistance. The invention provides a green method for preparing bakuchiol, aiming at the problems of low extraction rate, large loss of active ingredients, harm to health due to solvent residue, complicated extraction process and the like in the current bakuchiol extraction process, a deep eutectic solvent is used as an extraction medium, and a fructus psoraleae extract is extracted under the assistance of ultrasonic waves. The bakuchiol is further obtained through macroporous resin purification and separation, and the bakuchiol prepared by the method has remarkable antioxidant activity. According to the preparation method provided by the invention, the extraction content of the bakuchiol is remarkably increased, the problems existing in a traditional extraction process are solved, compared with a traditional organic solvent extract, the preparation method is simple and easy to operate, and the prepared bakuchiol is high in content, better in biological activity, green, safe, free of solvent residues and suitable for industrial production. The compound can be used for preparing more antioxidant drugs.

Description

Technical Field

[0001] This invention belongs to the field of biotechnology. More specifically, it relates to a green method for preparing psoralen and its application in antioxidation. Background Technology

[0002] Psoralea corylifolia is a traditional Chinese medicine. Its main active ingredient, psoralen, has a variety of biological activities such as anti-oxidation, anti-inflammation, and antibacterial properties. It can stimulate collagen production, reduce wrinkles, and improve skin elasticity and photodamage. In addition, it also has a variety of biological activities such as antibacterial, anti-tumor, liver protection, and neuroprotection. It is also gentler than traditional retinol and is widely used in the fields of skin care and medicine.

[0003] Existing methods for preparing psoralen include: (1) Organic solvent extraction, which commonly uses organic solvents such as ethanol, methanol, and acetone for extraction or reflux extraction. (2) Supercritical CO2 extraction (SFE), which utilizes the dissolving power of supercritical CO2 to extract under high pressure and low temperature. (3) Ultrasonic / microwave-assisted extraction, which strengthens solvent penetration through a physical field and shortens the extraction time. (4) Enzymatic hydrolysis, which uses cellulase and other enzymes to destroy cell walls and increase the release rate. (5) Steam distillation, which can be used to extract psoralen, but the extraction efficiency is lower than that of organic solvent extraction, and it can also lead to some heat-sensitive degradation or residues in the plant matrix, so it is rarely used.

[0004] However, traditional organic solvent extraction methods for psoralen yield low concentrations, resulting in psoralen with low bioactivity. Organic solvents also tend to remain in the psoralen, posing a residue risk and impacting product safety and application. Currently, supercritical carbon dioxide extraction of psoralen suffers from significant loss of active components. High-temperature extraction leads to psoralen degradation, reducing its bioactivity, and the extraction equipment is costly and complex. Ultrasonic / microwave-assisted extraction or steam extraction may damage heat-labile components. Enzymatic methods use expensive enzymes and may introduce protein impurities. As reported in existing studies, the highest extraction rate of psoralen is approximately 2.5%–3.5% (dry weight basis), which is relatively low. Extraction efficiency needs improvement, and the extracted psoralen content also needs further enhancement.

[0005] It is evident that traditional psoralen extraction processes suffer from problems such as high solvent toxicity, low extraction rate, high energy consumption, and severe environmental pollution. Currently, there is still a lack of a green method for the efficient extraction and preparation of psoralen to address these issues. Summary of the Invention

[0006] The technical problem to be solved by this invention is the defects and shortcomings of traditional extraction processes, such as high solvent toxicity, low extraction rate, high energy consumption, and serious environmental pollution. This invention provides a green method for preparing psoralen and its application in anti-oxidation.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: This invention provides a method for extracting and separating psoralen based on a eutectic solvent, comprising the following steps: S1. Preparation of eutectic solvent: Select hydrogen bond donor and hydrogen bond acceptor, mix them in a molar ratio of 1:(1~2), and heat and stir until a homogeneous transparent liquid is obtained; S2. Extraction: The pulverized Psoralea corylifolia powder was mixed with a eutectic solvent and extracted with ultrasound-assisted extraction. S3. Separation and purification: The extract obtained by centrifugation after extraction is the psoralen extract, which is further purified by macroporous resin, eluted, and concentrated under reduced pressure to obtain psoralenol.

[0008] To address the aforementioned issues, this invention proposes a green extraction method for psoralen based on eutectic solvents (DESs). Using a DES as the extraction medium, the psoralen extract is extracted under ultrasonic assistance, and then further purified and separated to obtain psoralen using macroporous resin. This method significantly increases the psoralen content while avoiding organic solvent residues and loss of active ingredients. The resulting psoralen exhibits significant antioxidant activity. Compared to traditional organic solvent extracts, the extract provided by this invention has higher bioactivity, better safety, and a simpler, lower-cost, and more environmentally friendly preparation process.

[0009] Preferably, the hydrogen bond donor in S1 is selected from one of citric acid, lactic acid, glucose, and glycerol.

[0010] Preferably, the hydrogen bond acceptor in S1 is selected from choline chloride or betaine.

[0011] More preferably, the hydrogen bond donor in S1 is lactic acid or glycerol.

[0012] More preferably, the hydrogen bond donor is lactic acid.

[0013] More preferably, the hydrogen bond acceptor in S1 is choline chloride.

[0014] This invention utilizes low-toxicity or non-toxic hydrogen bond donors and acceptors to synthesize a eutectic solvent, which offers significant advantages over traditional organic solvents: firstly, it avoids the toxicity issues of organic solvents, making it more environmentally friendly; secondly, by leveraging the unique hydrogen bonds and electrostatic interactions within the eutectic solvent, it enables the efficient extraction of psoralen from psoralen. This novel extraction method is not only simple to operate but also aligns with the development principles of green chemistry.

[0015] Preferably, the ratio of psoralen to eutectic solvent in S2 is 1:(5-20)g / mL.

[0016] Preferably, the ultrasonic-assisted extraction conditions in S2 are: temperature of 30-70℃, power of 200-500W, and extraction time of 15-60 minutes.

[0017] Preferably, the centrifugation rate in S3 is 5000–20000 r / min, and the time is 5–15 min.

[0018] As a preferred embodiment, the present invention provides a method for preparing Psoralea corylifolia extract: weigh dry Psoralea corylifolia powder, add DESs (water content 10-30%, v / v), set the ultrasonic extraction temperature to 30-70℃, the power to 200-500W, extract for 15-60 min, and then centrifuge at 5000-20000 rpm for 5-15 min to obtain the supernatant, which is the Psoralea corylifolia extract.

[0019] Preferably, in S3, before purification, wet packing is performed using 200-300 mesh silica gel with eluent; the eluent is ethanol and water, and the mass ratio of silica gel to psoralea extract is (1-5):1.

[0020] More preferably, the purification and elution method in S3 is as follows: after dissolving the psoralea extract in a 1-3% sodium hydroxide aqueous solution, the column is packed using a D101 macroporous resin wet packing method, the flow rate is controlled at 8-10 mL / min, the column is washed with water for 1-3 BV, then washed with 25-30% ethanol for 1-3 BV, and then eluted with 85-95% ethanol for 1-3 BV. The eluent is then concentrated under reduced pressure to obtain psoralen.

[0021] More preferably, the flow rate is controlled at 10 mL / min during purification. After the column is loaded, the column is washed with water for 3 BV, washed with 30% ethanol for 3 BV, and then eluted with 95% ethanol to obtain the eluent.

[0022] This invention provides a psoralen, which is prepared by the above method.

[0023] In particular, the psoralen obtained based on the preparation method of the present invention can be further purified by conventional purification methods in the art to improve the purity of psoralen.

[0024] The present invention also provides the use of psoralen prepared by the above method in anti-oxidation or in the preparation of anti-oxidation products.

[0025] The present invention has the following beneficial effects: This invention addresses the problems of low extraction rate, significant loss of active ingredients, harmful solvent residues, and cumbersome extraction processes often encountered in current psoralen extraction processes. It provides a green method for preparing psoralen by combining a eutectic solvent (DESs) with ultrasound-assisted extraction technology. Using a specific DESs as the extraction medium, extraction is performed under ultrasonic assistance. The extract is then centrifuged, purified, eluted, and concentrated to obtain psoralen, which exhibits significantly increased content, better bioactivity and safety, and significant antioxidant activity against DPPH and ABTS free radicals. + The free radical scavenging rate is high. Compared with traditional organic solvent extracts, the psoralen prepared by this invention has a higher content, better bioavailability, and better safety, solving the problems of high solvent toxicity, low extraction rate, high energy consumption, and serious environmental pollution in traditional extraction processes. The preparation method provided by this invention is simple and convenient, and can better extract psoralen from psoralea, efficiently separating psoralen while reducing pollution, increasing the psoralen content, and providing a safer and more efficient raw material for the preparation of more antioxidant products. Attached Figure Description

[0026] Figure 1 This is the infrared spectrum of bakuchiol.

[0027] Figure 2 This is the 1H NMR spectrum of psoralen.

[0028] Figure 3 This is the mass spectrum of bakuchiol.

[0029] Figure 4 The results show the determination of the DPPH free radical scavenging ability of different DES extracts.

[0030] Figure 5 The results show the determination of the ABTS free radical scavenging ability of different DES extracts. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0032] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0033] Example 1: Extraction method of psoralen S1: Accurately weigh equimolar amounts of HBA choline chloride and HBD citric acid, mix and heat at 80°C, and stir at 250 rpm for 2 hours. S2: Add 20% water during stirring until the system becomes a transparent and homogeneous liquid. S3: Transfer the prepared DESs into sample vials and allow them to cool naturally at room temperature until they are stable; S4: Accurately weigh 1 g of dried psoralea powder and add it to 10 mL of DESs in S3 above; S5: Ultrasonic extraction of Psoralea DESs solution was obtained for 30 min at a temperature of 45℃ and a power of 300 W. S6: Centrifuge the Psoralea DESs extract at 10000 rpm for 10 min and collect the supernatant to obtain the Psoralea extract. Store at -80℃ for later use. S7: After dissolving the psoralea extract in 210 mL of 2% sodium hydroxide aqueous solution, the column was packed using D101 macroporous resin wet packing. The liquid was poured into the macroporous resin, and the flow rate was controlled at 10 mL / min. After the column was loaded, the column was washed with water for 3 BV, washed with 30% ethanol for 3 BV, and then eluted with 95% ethanol for 3 BV. The eluent was then concentrated under reduced pressure to obtain psoralen. The percentage of psoralen was determined by HPLC.

[0034] Example 2 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that HBD uses lactic acid.

[0035] Example 3 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that HBD uses glucose.

[0036] Example 4 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that HBD uses glycerol.

[0037] Example 5 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that betaine is used for HBA and lactic acid is used for HBD.

[0038] Example 6 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that betaine is used for HBA and citric acid is used for HBD.

[0039] Example 7 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that betaine is used for HBA and glucose is used for HBD.

[0040] Example 8 The extraction method of psoralen provided in this embodiment differs from that in Example 1 in that betaine is used for HBA and glycerol is used for HBD.

[0041] Comparative Example 1: Organic Solvent Extraction Method S1. Extraction: Accurately weigh 10g of Psoralea corylifolia powder and add 100 mL of 95% ethanol; place the mixture in an oil bath at 70℃ and reflux for 2 hours; S2. Separation and purification: After extraction, filter while hot to obtain the extract; S3. Transfer the filtrate to a rotary evaporator and concentrate under reduced pressure; S4. The concentrated product is purified by passing it through a macroporous resin to obtain psoralen.

[0042] Comparative Example 2: Glacial acetic acid combined with ultrasound-assisted extraction method S1: Crush 1g of Psoralea corylifolia into powder, pass it through a 60-mesh sieve, and obtain Psoralea corylifolia powder; S2: Mix psoralea powder with 0.5 mL of glacial acetic acid, and then heat with steam at 100-105℃ for 10 min to obtain steamed psoralea powder. S3: After the temperature of the steamed psoralen powder was reduced to room temperature, it was ultrasonically extracted three times in 5 mL of anhydrous ethanol. The ultrasonic extraction time was 1 h each time, the extraction temperature was 25℃, and the extraction power was 85 kHz. The mixture was filtered, the filtrates were combined, and the mixture was concentrated under reduced pressure. The concentrate was purified by macroporous resin to obtain psoralen.

[0043] Characterization of DESs in Test Example 1 1. Preparation of DESs The method for preparing the eutectic solvents (DESs) in this embodiment is an improvement upon Abbott's research. The specific steps are as follows: Selected hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are mixed and heated at 20–80°C, and stirred at 200–300 rpm for 1–3 hours. During stirring, an appropriate amount of water is added until the system becomes a transparent and homogeneous liquid. Subsequently, the prepared DESs are transferred to sample vials and allowed to cool naturally at room temperature until stable. All prepared DESs maintain their clear and transparent liquid properties at room temperature. The specific components and ratios of the different eutectic solvents are shown in Table 1.

[0044] Table 1. Specific components and their proportions for preparing different eutectic solvents.

[0045] 2. Determination of the physicochemical properties of DESs Due to the high viscosity of DESs, the physicochemical properties were determined under conditions of 20% water content. Viscosity measurements were performed using a rotational rheometer (HAAKE MARS 60, Thermo Fisher Scientific, USA) in steady-state scanning mode at 25°C, with rotor speeds ranging from 0.1 to 1000 r / min. Each solvent was tested three times, and the average value was taken as the final viscosity of the DESs.

[0046] The principle of polarity determination is that the maximum absorption wavelength of Nile red (NR) dye in the UV-Vis region is easily affected by solvent polarity. The molar transition energy (ENR) of the probe dye in the solvent is used to assess the polarity of DESs. The specific procedure is as follows: Mix 1 mL of the test solution with 3 mL of 10 μg / mL NR-ethanol solution, and perform wavelength scanning using a UV-2450 spectrophotometer (Shimadzu, Japan), with a scanning range of 200–800 nm. Then, substitute the maximum absorption wavelength into the formula to calculate the ENR (kJ / mol) to characterize the polarity.

[0047]

[0048] in h It is Planck's constant; c It's the speed of light; N A It is Avogadro's constant.

[0049] The results are shown in Table 2. The eutectic solvent composed of betaine and glucose exhibited the highest viscosity. This is likely because both betaine and glucose are highly polar substances, and their interaction is primarily polar. Polar forces result in tight molecular bonds, hindering flow and leading to the high viscosity of the eutectic solvent. Furthermore, glucose molecules contain multiple hydroxyl groups, and the oxygen and nitrogen atoms in betaine molecules can form intermolecular hydrogen bonds with these hydroxyl groups. The presence of numerous hydrogen bonds enhances intermolecular forces and restricts molecular chain movement, further increasing the solution viscosity. Excessively viscous solvents may hinder the extraction of Psoralea corylifolia. High-viscosity eutectic solvents reduce molecular diffusion rates, affecting mass transfer of the solute from Psoralea corylifolia to the solvent. A viscosity range of 30–700 mPa·s is suitable for eutectic solvents. Lower viscosity eutectic solvents have better flowability, easily penetrating the internal pores and cellular structures of Psoralea corylifolia, ensuring sufficient contact with the extractable substance and facilitating extraction. In addition, the polarity of DESs in each group in the table is greater than 50, indicating that each solvent group has good dissolving power.

[0050] Table 2 Physicochemical properties of DESs

[0051] Test Example 2: Structural Characterization of Psoralen The content of psoralen prepared in Example 1 was determined using a Waters 2695 liquid chromatography system (specific method is described in Test Example 3). The pure peak product (i.e., the measured psoralen) was then used for further characterization and identification. The structure of the pure peak product (i.e., the further purified product) of psoralen from Example 1 was analyzed using an infrared spectrometer (Thermofisher IS50 R), with a sampling range of 4000–500 cm⁻¹. -1 The number of scans was 32, and the resolution was 4 cm. -1 Psoralen is a monoterpenoid phenolic compound whose structure includes a phenolic hydroxyl group, an isoprene side chain, and a benzene ring.

[0052] The results are as follows Figure 1 As shown, psoralen was present at 3360, 3080, 2965, and 1612 cm⁻¹. -1 A characteristic absorption peak appears nearby, including at 3360 cm⁻¹. -1 The absorption peak of associated hydroxyl groups (OH) in psoralen is located near 3080 cm⁻¹. -1 The nearby peak is the stretching vibration absorption peak of the unsaturated CH bond on the aromatic ring of psoralen, at 2965 cm⁻¹. -1 The nearby peak is the absorption peak of the methyl CH stretching vibration, at 1612 cm⁻¹. -1 The nearby absorption peak is that of phenyl groups. The purified product was identified as psoralen by infrared spectroscopy.

[0053] The structure of the purified product was then characterized using a Bruker 400MHz nuclear magnetic resonance spectrometer (AVANCE IIIHD 400). The tests were performed at room temperature in deuterated dimethyl sulfoxide (DMSO-d6) as the solvent.

[0054] The results are as follows Figure 2 As shown, the purified product underwent nuclear magnetic resonance (NMR) analysis, which revealed... 1 H NMR (400 MHz, CDCl3) δ 7.22-7.13 (m, 2H), 6.69 (d, J = 8.7 Hz, 2H), 6.28-5.91 (m, 2H), 5.80 (dd, J = 17.5,10.8 Hz, 1H), 5.20-4.88 (m, 2H), 1.93-1.83 (m, 1H), 1.60 (s, 1H), 1.51 (s,2H), 1.48-1.37 (m, 1H), 1.18 (t, J= 7.0 Hz, 1H), 1.12 (s, 3H).

[0055] Further mass spectrometry analysis was performed using a Thermo Scientific Q Exactive Orbitrap high-resolution mass spectrometer. Data acquisition and analysis were performed using Thermo Scientific Xcalibur software. The mass spectrometry conditions were as follows: mass spectrometry signal acquisition used positive and negative ion scanning mode; mass scan range m / z: 70–1000; ion source: H-ESI; positive ion spray voltage: 4000 V; negative ion spray voltage: 3000 V; sheath gas flow rate: 30 mL / min; auxiliary gas flow rate: 10 mL / min; capillary temperature: 320 °C; auxiliary gas temperature: 350 °C; resolution: 70000–17500 FWHM.

[0056] The results are as follows Figure 3 As shown, the purified product was finally identified as psoralen by mass spectrometry (the molecular weight of psoralen is 256).

[0057] Test Example 3: Determination of psoralen content The percentage of psoralen extracted in the example was determined using a Waters 2695 liquid chromatography system. The specific determination conditions were as follows: Diamonsil-C18 column (250 mm × 4.6 mm, 5 μm), mobile phase of acetonitrile-0.2% acetic acid aqueous solution, gradient elution, flow rate of 1.0 mL / min, detection wavelength of 260 nm, column temperature of 20 °C, and injection volume of 10 μL.

[0058] The results are shown in Table 3. The determination shows that the percentage of psoralen content obtained by the extraction in Examples 1-8 is all above 40%, which has a high extraction rate and is significantly better than the psoralen content obtained by the existing organic solvent extraction method; among them, the psoralen content obtained by Example 4 is the highest, reaching 46.25%.

[0059] Table 3 Percentage of psoralen content

[0060] Test Example 4: Antioxidant Capacity Accurately weigh 4 mg of DPPH and dissolve it in anhydrous ethanol, then dilute to a 100 mL amber volumetric flask to prepare a 0.1 mmol / L DPPH working solution. Take 2 mL of the sample solution from the control group (the psoralen extract obtained by replacing the eutectic solvent in Example 1 with anhydrous ethanol), Examples 1-8, and Comparative Examples 1-2 into 10 mL centrifuge tubes. Add 2 mL of 0.1 mmol / L DPPH working solution, mix thoroughly, and shake in the dark for 30 min. Measure the absorbance at 517 nm. Repeat the measurement three times for each sample, and calculate the clearance rate using the following formula.

[0061]

[0062] In the formula: A 0 represents the absorbance of 2 mL of DPPH solution after adding 2 mL of ethanol solution; A 1 represents the absorbance of 2 mL of sample solution after adding 2 mL of DPPH solution; A 2 represents the absorbance of 2 mL of sample solution after adding 2 mL of anhydrous ethanol.

[0063] The results are as follows Figure 4 As shown, the psoralen prepared using different DES extracts exhibits different DPPH free radical scavenging effects. Examples 1-8 all show good DPPH free radical scavenging effects, with Example 2 showing the best DPPH free radical scavenging effect.

[0064] Test Example 5: ABTS Free Radical Scavenging Ability Mix 2.45 mmol / L potassium persulfate with 7 mmol / L ABTS + The solutions were thoroughly mixed in equal volumes and incubated at 4°C in the dark for 16 hours. Then, the mixture was diluted with anhydrous ethanol, and the absorbance at 734 nm was 0.70 ± 0.02, yielding the ABTS+ working solution. 0.5 mL of samples from the control group (psoralen extract obtained by replacing the eutectic solvent in Example 1 with anhydrous water), Examples 1-8, and Comparative Examples 1-2 were mixed thoroughly with 4 mL of the ABTS working solution and reacted in the dark for 6 minutes. The absorbance was measured at 734 nm, and the clearance rate was calculated using the following formula.

[0065]

[0066] In the formula: A 0 represents the absorbance value of 0.5 mL of ethanol solution instead of the sample solution; A 1 represents the absorbance value of the sample group; A 2 is 4 mL of anhydrous ethanol instead of ABTS + The absorbance value of the working fluid.

[0067] The results are as follows Figure 5 As shown, the effects of psoralen prepared from different DES extracts on ABTS are illustrated. + The effects of free radical scavenging vary; examples 4, 6, and 8 show different effects of psoralen ABTS. + The free radical scavenging effect is better, and Example 6 shows the best scavenging effect on DPPH free radicals.

[0068] In summary, this invention addresses the problems of low extraction rate, significant loss of active ingredients, harmful solvent residues, and cumbersome extraction processes commonly found in current psoralen extraction processes. It provides a green method for preparing psoralen, using a eutectic solvent as the extraction medium and extracting psoralen under ultrasonic assistance. The psoralen is then further purified and separated using macroporous resin to obtain psoralen. The psoralen prepared by this method exhibits significant antioxidant activity. The preparation method provided in this invention significantly improves the extraction content of psoralen and solves the problems existing in traditional extraction processes. Compared with traditional organic solvent extracts, its preparation method is simple and easy to operate, yields high psoralen content, better bioactivity, is green and safe, and leaves no solvent residue, enabling its use in the preparation of more antioxidant drugs.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing psoralen, characterized in that, Includes the following steps: S1. Preparation of eutectic solvent: Select hydrogen bond donor and hydrogen bond acceptor, mix them in a molar ratio of 1:(1~2), and heat and stir until a homogeneous transparent liquid is obtained; S2. Extraction: The pulverized Psoralea corylifolia powder was mixed with a eutectic solvent and extracted with ultrasound-assisted extraction. S3. Separation and purification: The extract obtained by centrifugation after extraction is the psoralen extract, which is further purified by macroporous resin, eluted, and concentrated under reduced pressure to obtain psoralenol.

2. The method according to claim 1, characterized in that, The hydrogen bond donor in S1 is selected from one of citric acid, lactic acid, glucose, or glycerol.

3. The method according to claim 1, characterized in that, The hydrogen bond acceptor in S1 is selected from choline chloride or betaine.

4. The method according to claim 2, characterized in that, The hydrogen bond donors are lactic acid or glycerol.

5. The method according to any one of claims 1 to 3, characterized in that, The ratio of psoralen to eutectic solvent in S2 is 1:(5-20)g / mL.

6. The method according to any one of claims 1 to 3, characterized in that, The ultrasonic-assisted extraction conditions in S2 are: temperature 30–70℃, power 200–500W, and extraction time 15–60 minutes.

7. The method according to any one of claims 1 to 3, characterized in that, Before purification, S3 was packed into a column using a wet method with 200-300 mesh silica gel and eluent. The eluent used was ethanol and water, and the mass ratio of silica gel to Psoralea corylifolia extract was (1-5):

1.

8. The method according to claim 7, characterized in that, The purification and elution method in S3 is as follows: Psoralea extract is dissolved in 1-3% sodium hydroxide aqueous solution, then packed into a D101 macroporous resin column using a wet packing method. The flow rate is controlled at 8-10 mL / min. The column is washed with water for 1-3 BV, then washed with 25-30% ethanol for 1-3 BV, and then eluted with 85-95% ethanol for 1-3 BV. The eluent is then concentrated under reduced pressure to obtain psoralen.

9. A psoralen, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. The use of psoralen as described in claim 9 in antioxidation or in the preparation of antioxidant products.

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