Microemulsion entrapped with bakuchiol and preparation method thereof

Abstract

The invention discloses a microemulsion entrapped with bakuchiol. The microemulsion is prepared from bakuchiol, a main surfactant, a cosurfactant and water, wherein the mass ratio of the main surfactant to the cosurfactant to the bakuchiol is (4-7): (3-5): 1, water is added into the anhydrous raw material group, and the maximum addition amount of the water can be 99%. The bakuchiol-entrapped microemulsion is high in entrapment rate and thermodynamically stable, and can be infinitely diluted with water, and the particle size of the O / W microemulsion is 10-50nm, so that the skin permeability is high; the preparation method of the microemulsion is simple and convenient, high temperature or homogenization is not needed, and the microemulsion which is transparent, uniform and stable in appearance can be obtained through low-speed stirring at normal temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of cosmetics, and in particular relates to improving the solubility and bioavailability of bakuchiol, and specifically relates to a microemulsion encapsulating bakuchiol and a preparation method thereof. Background Art

[0002] Bakuchiol is a monovalent compound isolated from the leguminous plant Psoralea corylifolia. It has the whitening, antioxidant, anti-photoaging and soothing effects of retinol. Bakuchiol is mild, has low skin irritation and is non-photosensitive. It is a good substitute for retinol for sensitive skin groups. However, the oil solubility of bakuchiol limits its application in water-based cosmetics.

[0003] Microemulsion technology is a technology widely used to improve the bioavailability of fat-soluble or water-insoluble substances. It can disperse water-insoluble active substances into a relatively small particle size in an anhydrous system, which is close to monodisperse and has a small droplet size. Compared with other encapsulation systems, microemulsion is an optically transparent, slightly blue, thermodynamically stable, low-viscosity dispersion system formed spontaneously or under stirring at room temperature by a certain proportion of water, oil, surfactants and co-surfactants (polyhydroxy compounds, short-chain alcohols). According to the dispersion characteristics and the oil-water ratio, microemulsions can be divided into three types: O / W type, bicontinuous type, and W / O type.

[0004] Microemulsion is a transitional product between ordinary emulsion and micellar solution. It is more stable than ordinary emulsion, does not stratify even after high-speed centrifugation, and can solubilize more oil or water than micellar solution. The nano-scale droplet size allows the active ingredients to penetrate directly from the microemulsion droplets into the stratum corneum without merging with the stratum corneum, thereby improving the transdermal and absorption effects of the active ingredients. At the same time, a large amount of surfactants can reduce the diffusion barrier of the stratum corneum, and a large amount of water can cause hydration of the stratum corneum, thereby significantly increasing the subcutaneous absorption of the active ingredients.

[0005] Patent document CN117064775A discloses a translucent to transparent liquid containing bakuchiol and sphingosine substances and a preparation method thereof, which uses a formula of 0.5-15% bakuchiol, 0.5-10% sphingosine substances, 0.1-10% pH regulator, 1-10% polysorbate, 1-90% polyol, and 0.1-5% glycerol fatty acid esters. During the preparation process, it is necessary to heat to 40-80°C and finally dilute with water. The applicant reproduced its embodiment and found that a transparent microemulsion can be formed when a small amount of water is added, but as the amount of water added increases, it becomes turbid at room temperature; and when a small amount of water is added, it becomes turbid after being left for a period of time, indicating poor stability.

[0006] At present, conventional cosmetic emulsions have an opaque appearance, a complex preparation process, and are kinetically stable polydisperse systems with large particle sizes and poor transdermal and skin permeability, making it difficult for bakuchiol to exert its due efficacy. Due to the fat solubility of bakuchiol, there are few aqueous products on the market that add bakuchiol, and the emulsification system is rarely a microemulsion. Summary of the invention

[0007] The technical problem solved by the present invention is that the system for encapsulating bakuchiol in the prior art has low encapsulation rate, low solubility, inability to be infinitely diluted, thermodynamic instability, and large dispersed particle size resulting in poor transdermal properties.

[0008] In view of the above-mentioned defects of the prior art, the present invention provides a microemulsion encapsulating bakuchiol and a preparation method thereof.

[0009] In a first aspect of the present invention, a microemulsion encapsulating bakuchiol is provided, comprising bakuchiol, a primary surfactant, a co-surfactant and water, wherein the mass ratio of the primary surfactant, the co-surfactant and the bakuchiol is (4-7):(3-5):1, and the mass percentage of water is not more than 99%.

[0010] In some specific embodiments, the mass ratio of the main surfactant, the co-surfactant and bakuchiol is (5-6):3:1, and the mass percentage of water is not more than 95%.

[0011] In some specific embodiments, the main surfactant is selected from one or more of PEG-40 hydrogenated castor oil, polysorbate 80, olive oil PEG-7 esters, PEG-7 glyceryl cocoate, and PEG-8 glyceryl isostearate; the co-surfactant is one or more of 1,2-hexanediol, 1,5-hexanediol, 1,2-pentanediol, and 1,5-pentanediol.

[0012] Co-surfactants play a role in reducing interfacial tension and adjusting the HLB value of surfactants in the formation of microemulsions. They reduce the formation of crystals or latex by changing the polarity of the system, increasing the curvature of the interface, and reducing the viscosity of the system.

[0013] In some specific embodiments, the main surfactant includes a first main surfactant and a second main surfactant, the first main surfactant is selected from one or more of PEG-40 hydrogenated castor oil and polysorbate-80, and the second main surfactant is selected from one or more of olive oil PEG-7 esters, PEG-7 glyceryl cocoate, and PEG-8 glyceryl isostearate; the co-surfactant is one or more of 1,2-hexanediol, 1,5-hexanediol, 1,2-pentanediol, and 1,5-pentanediol.

[0014] In some specific embodiments, the mass ratio of the first primary surfactant to the second primary surfactant is 1.5 to 6:1.

[0015] Preferably, the mass ratio of the first primary surfactant to the second primary surfactant is 3 to 5:1.

[0016] Most preferably, the mass ratio of the first primary surfactant to the second primary surfactant is 4 to 5:1.

[0017] By constructing the types and proportions of oil phase, surfactant and co-surfactant, a microemulsion system with thermodynamic stability, high encapsulation rate and high skin permeability is prepared.

[0018] In a second aspect of the present invention, a method for preparing a microemulsion containing bakuchiol is provided, comprising the following steps:

[0019] S1. The co-surfactant and the surfactant are mixed and stirred at 15 to 25 ° C to obtain a mixed surfactant phase;

[0020] S2. dissolving bakuchiol in the mixed surfactant phase obtained in step S1, stirring at 15 to 25 ° C to obtain an anhydrous microemulsion;

[0021] S3. Add water to the anhydrous microemulsion obtained in step S2, and stir at 15-25° C. to obtain a microemulsion containing bakuchiol.

[0022] The preparation process can be stirring without heating, such as magnetic stirring at room temperature, and does not require high-pressure microfluidization, homogenization, heating and other conditions.

[0023] Furthermore, the magnetic stirring conditions of step S1, step S2 and step S3 are stirring at a rotation speed of 200 to 300 r for 5 to 10 minutes.

[0024] The temperature of step S1, step S2 and step S3 can be selected as normal temperature.

[0025] By constructing the types and proportions of the oil phase, surfactant, and co-surfactant and adopting the preparation method, the length of the hydrophobic chain in the microemulsion is kept equivalent to the linearity of the oil phase molecules, and the linear and orderly arrangement makes the phase interface more stable. At the same time, the presence of free branches on the hydrophobic chain of the surfactant is reduced or avoided to prevent it from affecting the arrangement between molecules, causing the tail end to move and causing phase separation.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The microemulsion encapsulating bakuchiol of the present invention has a high encapsulation rate and is thermodynamically stable, can be infinitely diluted with water, and has a particle size of 10 to 50 nm, so that the skin permeability is high. The preparation method of the microemulsion of the present invention is simple and does not require high temperature or homogenization. A microemulsion with a transparent, uniform and stable appearance can be obtained by low-speed stirring at room temperature.

[0028] The concept and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, features and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the particle size-volume distribution diagram of Example 1.

[0030] Figure 2 This is the particle size-volume distribution diagram of Example 2.

[0031] Figure 3 This is the particle size-volume distribution diagram of Example 6.

[0032] Figure 4 This is the particle size-intensity distribution diagram of Comparative Example 4.

[0033] Figure 5 This is the particle size-intensity distribution diagram of Comparative Example 10.

[0034] Figure 6 The appearance of each embodiment and comparative example under a black background

[0035] Figure 7 It is the appearance diagram of each embodiment and comparative example under white background.

[0036] Figure 8 This is the appearance diagram of comparative examples 11, 12, and 13 on a black background.

[0037] Fig. 9 This is the appearance diagram of Comparative Examples 11, 12, and 13 on a white background. DETAILED DESCRIPTION

[0038] In order to make the technical means, creative features, objectives and effects of the invention easier to understand, the invention is further described below with reference to specific diagrams. However, the invention is not limited to the following implementation cases.

[0039] It should be noted that the contents illustrated in the drawings in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any adjustments that are not creative should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0040] All reagents involved in the examples are commercially available products and can be commercial products.

[0041] The preparation method of the microemulsion containing bakuchiol used in each embodiment and comparative example is as follows:

[0042] The co-surfactant and the surfactant are mixed, and magnetically stirred at 200r~300r at 15~25°C for 5~10 minutes;

[0043] The bakuchiol is dissolved in the mixed surfactant, and the mixture is magnetically stirred at 200r to 300r for 5 to 10 minutes at 15 to 25°C, and the anhydrous microemulsion is thus prepared;

[0044] Add an appropriate amount of water to the anhydrous microemulsion, stir evenly with a magnetic force at 200-300r at 15-25°C for 5-10 minutes, and when the transparent and uniform appearance shows a faint blue light, the O / W microemulsion is prepared.

[0045] The particle size detection method is as follows:

[0046] The particle size was detected by BeNano 180 nanoparticle size analyzer. 2 ml of O / W microemulsion was taken into the PS sample cell. The equilibrium time was 120 s. At 25 °C, the scattering angle was 173°. The measurement was performed three times to obtain the average Z-particle size and polydispersity index PDI.

[0047] Example 1

[0048] A microemulsion containing bakuchiol, the mass percentage of each component is shown in Table 1 below:

[0049] Table 1 Microemulsion composition table of Example 1

[0050] Element Mass percentage / % PEG-40 Hydrogenated Castor Oil 2.5 Olive Oil PEG-7 Esters 0.5 1,2-Hexanediol 1.5 Bakuchiol 0.5 water 95 total 100

[0051] The preparation method is as follows:

[0052] Mix 1,2-hexanediol with PEG-40 hydrogenated castor oil and olive oil PEG-7 esters and stir magnetically at 300r for 10 minutes at 20°C;

[0053] The bakuchiol was dissolved in the mixed surfactant and magnetically stirred at 300r for 10 minutes at 20°C to prepare the anhydrous microemulsion.

[0054] Add an appropriate amount of water to the anhydrous microemulsion and stir evenly with a magnetic stirrer at 300r at 20°C for 10 minutes. When the transparent and uniform appearance shows a faint blue light, the O / W microemulsion is prepared.

[0055] Example 2

[0056] A microemulsion containing bakuchiol, the mass percentage of each component is shown in Table 2 below:

[0057] Table 2 Example 2 Microemulsion Components

[0058]

[0059]

[0060] The preparation method is as follows:

[0061] Mix 1,2-hexanediol, PEG-40 hydrogenated castor oil, and PEG-8 glyceryl isostearate, and stir magnetically at 300r for 10 minutes at 20°C;

[0062] The bakuchiol was dissolved in the mixed surfactant and magnetically stirred at 300r for 10 minutes at 20°C to prepare the anhydrous microemulsion.

[0063] Add an appropriate amount of water to the anhydrous microemulsion and stir evenly with a magnetic stirrer at 300r at 20°C for 10 minutes. When the transparent and uniform appearance shows a faint blue light, the O / W microemulsion is prepared.

[0064] Example 3

[0065] A microemulsion containing bakuchiol, the mass percentage of each component is shown in Table 3 below:

[0066] Table 3 Microemulsion composition table of Example 3

[0067] Element Mass percentage / % PEG-40 Hydrogenated Castor Oil 2.5 PEG-7 Glyceryl Cocoate 0.5 1,2-Hexanediol 1.5 Bakuchiol 0.5 water 95 total 100

[0068] The preparation method is as follows:

[0069] Mix 1,2-hexanediol, PEG-40 hydrogenated castor oil, and PEG-7 glyceryl cocoate, and stir magnetically at 300r for 10 minutes at 20°C;

[0070] The bakuchiol was dissolved in the mixed surfactant and magnetically stirred at 300r for 10 minutes at 20°C to prepare the anhydrous microemulsion.

[0071] Add an appropriate amount of water to the anhydrous microemulsion and stir evenly with a magnetic stirrer at 300r at 20°C for 10 minutes. When the transparent and uniform appearance shows a faint blue light, the O / W microemulsion is prepared.

[0072] Comparative Example 1

[0073] The mass percentage of each component is shown in Table 4 below:

[0074] Table 4 Comparative Example 1 Components

[0075] Element Mass percentage / % PEG-40 Hydrogenated Castor Oil 1.5 Olive Oil PEG-7 Esters 1.5 1,2-Hexanediol 1.5 Bakuchiol 0.5 water 95 total 100

[0076] The preparation method is as follows:

[0077] Mix 1,2-hexanediol with PEG-40 hydrogenated castor oil and olive oil PEG-7 esters and stir magnetically at 300r for 10 minutes at 20°C;

[0078] The bakuchiol was dissolved in the mixed surfactant and magnetically stirred at 300r for 10 minutes at 20°C to prepare the anhydrous microemulsion.

[0079] Add appropriate amount of water to the above mixture and stir evenly with magnetic force at 300r at 20℃ for 10 minutes.

[0080] Examples 1 to 8 and Comparative Examples 1 to 10 are summarized in Table 5 below. The preparation methods of all examples refer to Example 1, and the preparation methods of all comparative examples refer to Comparative Example 1.

[0081] Table 5 Component dosage ratios and experimental results of Examples 1 to 8 and Comparative Examples 1 to 13

[0082]

[0083] Continue to add water to the microemulsions of Examples 1 to 8 above, the appearance of the system remains unchanged, and it can be infinitely diluted.

[0084] Figure 1 , Figure 2 , Figure 3 They are the particle size-volume distribution diagrams of Example 1, Example 2, and Example 6 respectively; Figure 6 , Figure 7 The following are the appearance pictures of each embodiment and comparative example under black background and white background respectively. It can be seen from the experimental results that the particle size of the microemulsion of the present invention is in the range of 10-50nm, the microemulsion of each embodiment is transparent and uniform, with a slight blue light, while each comparative example is turbid. The present invention is thermodynamically stable at a high encapsulation rate of bakuchiol and can be infinitely diluted with water.

[0085] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A microemulsion containing bakuchiol, comprising bakuchiol, a primary surfactant, a co-surfactant, and water, characterized in that: The mass ratio of the main surfactant, the auxiliary surfactant and the bakuchiol is (4-7):(3-5):1, and the mass percentage of water is not more than 99%.

2. The microemulsion containing bakuchiol according to claim 1, characterized in that: The mass ratio of the main surfactant, the auxiliary surfactant and bakuchiol is (5-6):3:1, and the mass percentage of water is not more than 95%.

3. The microemulsion containing bakuchiol according to any one of claims 1 or 2, characterized in that: The main surfactant is selected from one or more of PEG-40 hydrogenated castor oil, polysorbate 80, olive oil PEG-7 esters, PEG-7 glyceryl cocoate, and PEG-8 glyceryl isostearate; the co-surfactant is one or more of 1,2-hexanediol, 1,5-hexanediol, 1,2-pentanediol, and 1,5-pentanediol.

4. The microemulsion containing bakuchiol according to any one of claims 1 or 2, characterized in that: The main surfactant includes a first main surfactant and a second main surfactant, the first main surfactant is selected from one or more of PEG-40 hydrogenated castor oil and polysorbate-80, and the second main surfactant is selected from one or more of olive oil PEG-7 esters, PEG-7 glyceryl cocoate, and PEG-8 glyceryl isostearate; the co-surfactant is one or more of 1,2-hexanediol, 1,5-hexanediol, 1,2-pentanediol, and 1,5-pentanediol.

5. The microemulsion containing bakuchiol according to claim 4, characterized in that: The mass ratio of the first main surfactant to the second main surfactant is 1.5 to 6:

1.

6. The microemulsion containing bakuchiol according to claim 5, characterized in that: The mass ratio of the first main surfactant to the second main surfactant is 3 to 5:

1.

7. The microemulsion containing bakuchiol according to claim 6, characterized in that: The mass ratio of the first main surfactant to the second main surfactant is 4 to 5:

1.

8. The method for preparing a microemulsion containing bakuchiol according to any one of claims 1 to 7, comprising the following steps: S1. The co-surfactant and the surfactant are mixed and stirred at 15 to 25 ° C to obtain a mixed surfactant phase; S2. dissolving bakuchiol in the mixed surfactant phase obtained in step S1, stirring at 15 to 25 ° C to obtain an anhydrous microemulsion; S3. Add water to the anhydrous microemulsion obtained in step S2, and stir at 15-25° C. to obtain a microemulsion containing bakuchiol.

9. The preparation method according to claim 8, characterized in that: The magnetic stirring conditions of step S1, step S2 and step S3 are stirring at a rotation speed of 200 to 300 r for 5 to 10 minutes.

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