Preparation method of high-absorbability bisabolol

Abstract

The invention discloses a preparation method of high-absorptivity bisabolol, relates to the technical field of natural product chemistry, and solves the problem of insufficient preparation methods of bisabolol in the prior art. The key point of the technical scheme is that the preparation method comprises the following steps: a) supercritical CO2 extraction: crushing compositae plant raw materials to 40-60 meshes; performing three-stage gradient extraction under the conditions that the pressure is 25-35 MPa, the temperature is 45-55 DEG C and the flow rate of CO2 is 15-25 L / h, the extraction time is 2-3 hours, and an entrainer is 0.1-0.5% ethanol; the method has the effects that a supercritical CO2 extraction technology is adopted, so that organic solvent residues are avoided, and the safety of the product is improved; the molecular distillation purification further improves the purity of the bisabolol; according to the nanocrystallization technology, the size of the bisabolol crystal is remarkably reduced, the specific surface area is increased, and the solubility and permeability of the bisabolol in the skin are improved; the freeze-drying process maintains the nanostructure and activity of bisabolol, and improves the stability and bioavailability of the product.

Description

Technical Field

[0001] The invention relates to the technical field of natural product chemistry, in particular to a method for preparing highly absorbable bisabolol. Background Art

[0002] Bisabolol is an important natural sesquiterpenoid compound found primarily in plants such as chamomile and calendula. It possesses significant anti-inflammatory, sedative, repairing, and skin-healing properties. In recent years, with the widespread application of natural products in cosmetics and medicine, market demand for bisabolol has been growing.

[0003] As the global cosmetics market shifts toward natural ingredients and targeted efficacy, demand for bisabolol is experiencing explosive growth. According to statistics, the global bisabolol market reached $180 million in 2022 and is projected to exceed $350 million by 2025, achieving a compound annual growth rate of 24.7%. However, existing technologies for the extraction, purification, and formulation of bisabolol still face the following key technical bottlenecks:

[0004] Traditional extraction processes are inefficient. Currently, the industry mainly uses solvent extraction (such as ethanol reflux extraction and petroleum ether immersion) to obtain crude bisabolol extracts from plant raw materials. This method has significant drawbacks: low yield: the yield of solvent extraction methods reported in the literature is only 0.8-1.2% (based on the weight of dried flowers), and multiple repeated extractions are required to achieve basic purity; solvent residue: residual organic solvents (such as n-hexane and methanol) are difficult to completely remove, resulting in an increased risk of product toxicity (EU ECOCERT certification requires a solvent residue of <50 ppm); thermal damage: traditional high-temperature extraction processes (>60°C) easily lead to isomerization of bisabolol (generating by-products such as α-bisabolol acetate). HPLC testing has confirmed that the by-product content under conventional processes can reach 3-5%, seriously affecting product efficacy; permeability barriers caused by molecular structure. The molecular characteristics of bisabolol significantly limit its transdermal absorption efficiency: its large molecular weight (222.36 g / mol) and rigid bicyclic structure result in a transdermal diffusion coefficient (D value) of only 0.23×10 -6 cm 2 / s (in vitro Franz diffusion cell test data); while its high lipid solubility (logP = 3.17) facilitates stratum corneum penetration, it has difficulty breaking through the epidermal hydration barrier, with retention in the stratum corneum as high as 68% (confocal microscopy observations); its low solubility: only slightly soluble in water (0.03 mg / mL at 25°C), limiting its application in aqueous cosmetic matrices;

[0005] Due to the limitations of existing formulation technology, most of the currently available bisabolol products are prepared using a simple recrystallization process, which has the following defects: the crystal size is too large: the average particle size of conventional crystalline products is 20-50 μm (measured by laser particle size analyzer), and the specific surface area is only about 15 m 2 / g, resulting in a low dissolution rate constant (k = 0.003s-1); therefore, there is an urgent need to develop a preparation method that is efficient, environmentally friendly and can significantly improve the absorption rate of bisabolol. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing highly absorbable bisabolol to solve the problems raised in the above background technology.

[0007] This invention provides a method for preparing highly absorbable bisabolol based on the synergistic effects of supercritical fluid extraction, molecular distillation, and nanocrystallization. Through precise control of process parameters, this method achieves low-temperature, efficient extraction, high-purity separation, and nanoscale dispersion of bisabolol, significantly improving its transdermal absorption and bioavailability. The following details the technical solution, technical principles, and innovation:

[0008] 1. In-depth analysis of the technical solution

[0009] 1. Optimization of supercritical CO2 extraction process

[0010] The process parameters are selected based on the three-stage gradient extraction mode:

[0011] Pretreatment stage: extraction pressure 25MPa, temperature 45℃, destroying the plant cell wall structure and fully releasing the bisabolol precursor;

[0012] Main extraction stage: pressure increased to 30MPa, temperature 50℃, at which point the CO2 density reached 0.92g / cm 3 (close to the solubility inflection point of bisabolol), achieving efficient dissolution of the target ingredient;

[0013] Post-processing stage: the pressure is reduced to 25 MPa and the temperature is 55°C, and polar impurities (such as flavonoid glycosides) are removed by decompression analysis.

[0014] HPLC-DAD analysis confirmed that under these conditions, the yield of bisabolol reached 2.3±0.15% (an increase of 176% compared with the traditional solvent method), and the proportion of α-bisabolol was ≥98% (GC-MS data).

[0015] Solvent residue control technology: In the decomposition stage, 0.5% ethanol is injected as an entrainer, and the competitive dissolution effect of CO2 is used to reduce the total amount of residual solvent to 8ppm (in line with USP <467> standard), and inhibited the isomerization reaction of bisabolol (DSC showed that the amount of isomer generated was reduced to 0.8%).

[0016] 2. Molecular distillation purification mechanism

[0017] Molecular distillation device design: A three-stage falling film molecular distillation device is used, the feed rate is controlled at 1.2 mL / min, and the distillation temperature gradient is set to:

[0018] First stage: 160℃ (separation of light components such as terpenes);

[0019] Second stage: 195℃ (enrichment of the main component of bisabolol);

[0020] The third stage: 210℃ (removal of high boiling point impurities).

[0021] The system pressure (≤0.1 Pa) was monitored in real time by a vacuum gauge to ensure that the distillation efficiency of bisabolol reached 92.3%.

[0022] Purity improvement mechanism: Based on the difference in the molecular mean free path of bisabolol and impurities (65nm for α-bisabolol and 72nm for β-bisabolol), effective separation of monomer and dimer is achieved by adjusting the condensation surface temperature difference (ΔT = 8°C), and the final product HPLC purity is ≥99.2%.

[0023] 3. Breakthrough in key nanocrystallization technologies

[0024] Solvent system innovation: Developed an ethanol-water (3:1) mixed solvent with a dielectric constant (24.5@25°C) between that of pure ethanol (24.3) and water (78.5). This solvent can both dissolve bisabolol (solubility up to 0.25 mg / mL) and induce crystal nucleation through the solvent's volatility gradient.

[0025] Experimental data: When the ethanol ratio is lower than 25%, the crystal growth rate decreases by 50%; when it is higher than 35%, the nanoparticles tend to agglomerate (PDI>0.4).

[0026] Ultrasonic-assisted crystallization mechanism: Using a 40kHz variable-frequency ultrasonic field, the cavitation effect reduces the size of solvent molecular clusters to the nanoscale (average particle size 8nm determined by dynamic light scattering), promoting the orderly arrangement of bisabolol molecules.

[0027] Process parameter optimization: ultrasonic power density: 1.2 W / mL (too low to form effective cavitation nuclei, too high to cause crystal breakage); processing time: 45 minutes (crystal growth kinetics studies show that size distribution equilibrium is reached at this time).

[0028] Surfactant synergy: Polysorbate 80 (HLB value 15) stabilizes nanoparticles by reducing interfacial tension (from 52 mN / m to 28 mN / m). Its concentration needs to be controlled at 1.0 ± 0.2%. Too low a concentration can easily lead to Ostwald ripening, while too high a concentration can inhibit crystal growth.

[0029] 4. Freeze-drying process design

[0030] Freezing curve control: A step-by-step cooling process is employed: primary cooling: -20°C for 1 hour (to form initial ice crystals); secondary cooling: -40°C for 2 hours (to complete the glass transition); and final drying: vacuum sublimation at -50°C (residual moisture ≤ 2%). This process achieves 98% nanocrystalline structural integrity (no collapse observed by SEM) and reduces shrinkage by 60% compared to conventional freeze-drying.

[0031] Antioxidant protection strategy: 0.1% ascorbyl palmitate was added to the freeze-dried protective agent to inhibit the oxidation of bisabolol through a hydrogen bond network (accelerated tests showed that the content decreased from 12.3% to 1.8% in 6 months).

[0032] 2. Technical Principles and Innovation

[0033] 1. Multi-physics field synergistic efficiency mechanism

[0034] Coupling supercritical CO2 extraction with molecular distillation: By combining the efficient penetration of supercritical fluid into plant cells with the molecular-level separation capabilities of molecular distillation, we achieve targeted enrichment of bisabolol. Compared to traditional processes, overall extraction efficiency is increased by 2.3 times, while energy consumption is reduced by 40%.

[0035] Quantum confinement effect of nanocrystals: When the size of bisabolol crystals decreases below 100nm, their energy levels split (according to quantum confinement theory), resulting in an increase in the probability of molecular vibration energy level transitions. In vitro transdermal experiments showed that the cumulative drug permeation (Franz diffusion cell method) increased from 12.4μg / cm2 of traditional preparations to 2 Increased to 28.9 μg / cm 2 .

[0036] 2. Key technological innovations

[0037] Low-temperature continuous production technology: The entire operating temperature is ≤55°C, avoiding the thermal degradation of bisabolol (HPLC detection shows that by-products are reduced to less than 0.3%).

[0038] Crystal form controllable technology: by regulating the solvent evaporation rate (ethanol volatility coefficient K = 0.12h-1), the product exists in a stable α crystal form (XRD spectrum shows characteristic peaks Corresponding to the (002) crystal plane), the transdermal absorption rate is increased by 37% compared with the β crystal form.

[0039] Intelligent process control: Integrated online near-infrared spectroscopy (NIR) monitors bisabolol concentration in real time (accuracy ±0.3%), combined with a PID algorithm to dynamically adjust ultrasonic power and solvent flow, with batch-to-batch consistency RSD ≤1.5%.

[0040] 3. Technical Effects and Comparative Data

[0041]

[0042] 4. Industrial Application Potential

[0043] This process has passed pilot testing (production scale: 100kg / batch), with a payback period of ≤2.3 years. Compared with traditional processes, it reduces energy consumption per unit of product by 55% (based on steam consumption) and solvent usage by 92% (in line with green chemistry principles). Furthermore, the product meets ECOCERT organic certification standards, providing significant market competitive advantages.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. Using supercritical CO2 extraction technology to avoid organic solvent residue and improve product safety;

[0046] 2. Molecular distillation purification further improves the purity of bisabolol;

[0047] 3. Nano-crystallization technology significantly reduces the size of bisabolol crystals, increases the specific surface area, and improves its solubility and permeability in the skin;

[0048] 4. The freeze-drying process maintains the nanostructure and activity of bisabolol, improving the stability and bioavailability of the product. DETAILED DESCRIPTION

[0049] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] Example 1: Optimization of supercritical CO2 extraction-molecular distillation process

[0051] Raw material pretreatment: Freshly harvested German chamomile flowers (Matricaria chamomilla L.) were dried in a forced air oven at 50°C to a constant weight (moisture content ≤ 8%), then pulverized using a universal grinder to a 40-mesh size (0.425 mm sieve size). The raw materials were placed in a supercritical CO2 extraction vessel and extracted according to the parameters in Table 1:

[0052]

[0053] Key points of operation: The system is pre-cooled to -20°C and then filled with food-grade CO2 (purity ≥99.9%). The pressure fluctuation range of the extraction kettle is ≤±0.2MPa (dynamically adjusted by the back pressure valve). The temperature of the separation kettle I is set to 45°C, and the temperature of the separation kettle II is set to 60°C. Experimental results: The yield of the crude extract is 3.2% (based on the weight of the dried flower). HPLC analysis shows that the content of bisabolol is 78.5%, and the α-isomer accounts for 92.3%. Example 2: Verification of molecular distillation purification process parameters The crude extract (200 g) obtained in Example 1 was put into a three-stage molecular distillation apparatus (model: BenchTop-MD100) and purified according to the parameters in Table 2:

[0054]

[0055] Key equipment parameters: Evaporation surface effective area: 0.6 m2 Condensation surface temperature: -20°C (liquid nitrogen circulation cooling) Vacuum pump ultimate vacuum: 5×10 -4 Pa experimental results: total recovery rate: 89.2% final product purity: HPLC ≥ 99.1% (α-bisabolol accounts for 96.5%).

[0056] Example 3: Orthogonal experiment for optimizing nanocrystallization process parameters using L9(3 4 ) Orthogonal table was used to optimize the key parameters of nanocrystallization. The experimental design and results are shown in Table 3:

[0057]

[0058] Range analysis: Ranking of primary and secondary factors: ultrasonic power > solvent ratio > surfactant concentration. Optimal combination: A3B2C2 (ethanol: water = 3:1, surfactant 1.0%, ultrasonic power 120 W). Verification experiment: Three batches of production were repeated according to the optimal parameters, and the average particle size of the obtained nanoparticles was 85±12 nm, the polydispersity index (PDI) was 0.18±0.03, and the encapsulation efficiency was 93.2±1.5%.

[0059] Example 4: Study on the Effect of Freeze-Drying Process on Crystalline Form The effects of three freeze-drying procedures on the crystal form of bisabolol were compared. The results are shown in Table 4:

[0060]

[0061] Key findings: A step-cooling program (-40°C → -50°C gradient cooling) can maintain the stability of the α-crystal. Adding 0.1% ascorbyl palmitate can increase the oxidative stability by 8 times (accelerated test 6 months content retention rate 98.2%).

[0062] Example 5: Industrial-scale production verification The process of the present invention was implemented in a pilot production line (processing capacity 100 kg / batch), and the key data are as follows:

[0063]

[0064] Equipment configuration list: Supercritical CO2 extraction system: German HAUSER CXP-500 molecular distillation unit: Japanese ULVAC R&D ZMD-200 nanocrystallization reactor: German IKA HPH-500 homogenizer emulsifier freeze dryer: American VirTis Advantage Plus.

[0065] Comparative Example: Comparison of the effects of traditional process and the present invention

[0066]

[0067] Verification of process scale-up effect The feasibility of process scale-up was verified through dimensional analysis, and the key dimensionless parameters remained consistent:

[0068]

[0069] Conclusion: Under similar scale-up criteria, the pilot product has good performance in terms of particle size distribution (PDI = 0.19) and transdermal absorption rate (33.9 μg / cm 2 The results of key indicators such as ·h) are highly consistent with those of the small-scale test, proving that the process has good feasibility of scale-up.

[0070] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

[0071] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing highly absorbable bisabolol, characterized in that: The following steps are involved: a) Supercritical CO2 extraction: The Asteraceae plant material was crushed to 50 mesh and subjected to three-stage gradient extraction at a pressure of 30 MPa, a temperature of 55°C, and a CO2 flow rate of 25 L / h for 3 hours. The entrainer was 0.5% ethanol. b) Molecular distillation purification: The crude extract was subjected to three-stage molecular distillation under vacuum conditions of 0.1 Pa, with the first stage distillation temperature at 180°C to separate light components, the second stage distillation temperature at 220°C to collect the main bisabolol, and the third stage distillation temperature at 230°C to remove high-boiling-point impurities; c) Nanocrystal Preparation: Bisabolol concentrate was dissolved in an ethanol-water mixture at a volume ratio of 2:

1. A surfactant, polysorbate 80, was added at a concentration of 1.0%. The mixture was ultrasonically treated at a frequency of 60 kHz and a power density of 1.5 W / mL for 90 minutes to form nanocrystals with a particle size of 150 nm. d) Freeze drying: The nanocrystal suspension was pre-frozen at -40°C for 4 hours, gradually heated to -10°C and maintained for 6 hours, and finally vacuum dried to a residual moisture content of 1.5% to obtain a highly absorbable bisabolol product.

2. The method for preparing highly absorbable bisabolol according to claim 1, wherein: In the supercritical CO2 extraction step: The extraction pressure was controlled in stages as follows: the initial pressure was 20 MPa and maintained for 0.5 h, then gradually increased to 30 MPa and maintained for 1.5 h, and finally reduced to 20 MPa to complete the extraction; The entrainer injection method was pulse addition, with 0.2 mL of ethanol solution injected every 10 minutes at a concentration of 0.5%; The CO2 density in the extraction kettle is controlled at 0.95g / cm 3 , achieved by adjusting the dynamic balance of temperature and pressure.

3. The method for preparing highly absorbable bisabolol according to claim 1, wherein: In the molecular distillation purification step: The first-stage distillation tower adopts a spiral guide plate structure, and the condensation temperature is -30℃; The distance between the evaporation surface and the condensation surface of the secondary distillation tower is 25 cm, and the feed rate is 1.5 mL / min; The three-stage distillation tower adopts pulse vacuum technology, with a pressure fluctuation range of ±0.05Pa and a distillation efficiency of 93%.

4. The method for preparing highly absorbable bisabolol according to claim 1, wherein: In the nanocrystallization step: The mixed solvent is an ethanol-water system, in which ethanol accounts for 80% (v / v), and the dielectric constant of the solvent is 30, measured at 25°C; The surfactant is selected from at least one of polysorbate 80, poloxamer 188 or sodium lauryl sulfate; Ultrasonic treatment was performed in intermittent mode: ultrasonication for 30 seconds / rest for 10 seconds, and the total treatment time was extended to 120 minutes; The crystallization endpoint was monitored by dynamic light scattering, and the reaction was terminated when the particle size distribution coefficient reached 0.

25.

5. The method for preparing highly absorbable bisabolol according to claim 1, wherein: In the freeze-drying step: During the pre-freezing stage, programmed cooling was used: the temperature was lowered from room temperature to -40°C at a rate of 10°C / min, maintained for 2 hours, and then raised to -10°C at a rate of 5°C / h; The vacuum drying stage is divided into two stages: the first stage pressure 10 -3 Pa is maintained for 8 hours, and the second stage pressure is 10 -4 Pa is maintained for 24 hours; The freeze-drying protective agent is selected from one of trehalose, mannitol or ascorbyl palmitate, and the added amount is 0.3%.

6. The method for preparing highly absorbable bisabolol according to any one of claims 1 to 5, characterized in that: The Compositae plant raw materials include but are not limited to: German chamomile flowers contain 0.6% bisabolol; The whole herb of calendula has a bisabolol content of 0.3%; Salix sabdariffa leaf extract with a bisabolol content of 0.4%.

7. The method for preparing highly absorbable bisabolol according to any one of claims 1 to 5, characterized in that: Add pre-dispersion treatment before the nano-crystallization step: The bisabolol concentrate was mixed with nano-titanium dioxide (particle size 50 nm) at a mass ratio of 1:0.05; The mixture was treated 5 times using a high-pressure homogenizer at a pressure of 200 MPa to achieve a dispersion uniformity of 95% for bisabolol.

8. The method for preparing highly absorbable bisabolol according to any one of claims 1 to 5, characterized in that: The final form of the product is: Nanocrystalline powder, average particle size 120nm, specific surface area 60m 2 / g, measured by BET method; Nanoemulsion system, particle size 100 nm, Zeta potential -25 mV, measured by laser particle size analyzer; Solid lipid nanoparticles, encapsulation efficiency is 95%, and drug loading is 25%.

9. The method for preparing highly absorbable bisabolol according to any one of claims 1 to 5, characterized in that: The method integrates an online monitoring system during the preparation process: Near-infrared spectroscopy was used to monitor the bisabolol concentration in real time during the supercritical CO2 extraction stage; During the molecular distillation stage, the distillate components are detected by mass spectrometry; Dynamic light scattering was used to control the particle size distribution during the nanocrystallization stage.

10. The method for preparing highly absorbable bisabolol according to any one of claims 1 to 5, characterized in that: The bisabolol product is used for: In the cosmetics field, as a transdermal absorption enhancer, the addition amount is 5%; In the pharmaceutical field, it can be made into a transdermal patch or nano cream with a drug release time of 12 hours; In the field of functional foods, as a natural antioxidant, the added amount is 0.5%.

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