Linoleic acid-including liposome-containing composition

Abstract

To provide a composition containing liposome including linoleic acid, which has a relatively small particle diameter of a liposome, and excellent skin retentivity of linoleic acid included in a liposome.SOLUTION: A composition contains liposome including linoleic acid, and has pH6.2 to 9.5, where a Z average particle diameter of the liposome is 90nm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a composition containing liposomes encapsulating linoleic acid, a method for producing a composition containing liposomes encapsulating linoleic acid, and the like.

Background Art

[0002] Linoleic acid has a whitening effect and is a polyunsaturated fatty acid incorporated into external compositions such as cosmetics, quasi-drugs, and external pharmaceuticals. Generally, since polyunsaturated fatty acids have poor stability over time, techniques for stably incorporating them into compositions have been studied. For example, in Patent Document 1, a technique for improving the stability over time of polyunsaturated fatty acids by incorporating a specific amount of vitamin E or the like into polyunsaturated fatty acids to form an emulsion has been studied.

[0003] Liposomes are artificial capsules composed of phospholipids and the like, which are the main components of biological membranes. Phospholipids have an amphiphilic structure and form a lipid bilayer (in other words, a bimolecular membrane). Since oil-soluble substances can be incorporated into the bimolecular membrane, for some oil-soluble substances, the oil-soluble substances are encapsulated in liposomes for the purpose of enhancing their stability and the like by utilizing this property.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, generally, liposomes in a composition are unstable by themselves. That is, since liposomes in a composition can easily disintegrate, it is assumed that the oil-soluble substance encapsulated in the bilayer membrane of the liposome is released outside the liposome due to the disintegration of the liposome. As a result, when the oil-soluble substance is a polyunsaturated fatty acid, the effect of improving the stability over time of the polyunsaturated fatty acid expected by encapsulation in the liposome may not be obtained.

[0007] Before the liposomes in the composition reach the point of disintegration, there may be a process in which a plurality of liposomes aggregate and then coalesce into larger liposomes. Also, even if they do not reach the point of disintegration, the liposomes in the composition can aggregate and coalesce to cause separation, precipitation, etc., which can cause a non-uniform appearance. Such a composition with such an appearance is generally not preferred for traders and consumers.

[0008] The ease of aggregation of liposomes in a composition can be evaluated by Stokes' law, which represents the terminal velocity when small particles settle in a fluid. Stokes' law is shown below.

[0009]

Equation

[0010] When the v obtained by the above equation is a positive value (i.e., ρ p > ρ f ), the particle is considered to move downward in the vertical direction. When v is a negative value (i.e., ρ p < ρ f ), the particle is considered to move upward in the vertical direction. Also, the larger the absolute value of v, the faster the particle moves (i.e., it is easier to aggregate, precipitate, separate, etc.).

[0011] From Stokes' equation, it is understood that the smaller the radius of the particle, the smaller the difference in mass density between the particle and the fluid, and the higher the kinematic viscosity of the fluid, the smaller the terminal velocity of the particle (i.e., it is difficult to aggregate, precipitate, separate, etc., and the dispersed state of the particle is likely to be kept stable).

[0012] On the other hand, in Non-Patent Document 1, the relationship between the particle size of liposomes and percutaneous diffusibility has been studied. Specifically, the authors of Non-Patent Document 1 set a human skin equivalent membrane between the donor compartment and the receptor compartment of a Franz cell, filled the donor compartment with a donor solution containing liposomes, and filled the receptor compartment with a receptor solution not containing liposomes. When the change over time in the amount of liposomes in the receptor solution was evaluated using the said evaluation system, it was reported that the smaller the particle size of the liposomes, the faster the liposomes permeated through the human skin equivalent membrane and diffused into the receptor solution.

[0013] ​​From the description of Non-Patent Document 1, it is considered that the smaller the particle size of the liposome, the less likely the liposome is to remain inside the skin and the more quickly it is absorbed into the body. On the other hand, the larger the particle size of the liposome, the more likely the liposome is to remain inside the skin. That is, the smaller the particle size of the liposome, the more likely the stability of the liposome over time tends to improve. On the other hand, the larger the particle size of the liposome, the higher the skin retention of the liposome is considered to be. Thus, there has been a situation where it is difficult to reconcile the stability of the liposome over time with the skin retention of the liposome and the oil-soluble substance encapsulated in the liposome.

[0014] In view of the above circumstances, the main object of the present inventors is to provide a composition containing liposomes encapsulating linoleic acid, which has a relatively small particle size of the liposomes and excellent skin retention of the linoleic acid encapsulated in the liposomes.

Means for Solving the Problems

[0015] The present inventors have found that the above problems may be solved by a composition containing liposomes encapsulating linoleic acid, having a pH of 6.2 to 9.5, and having a Z-average particle size of the liposomes of 90 nm or less. Then, through further improvements, the present disclosure has been completed.

[0016] The present disclosure includes, for example, the subject matters described in the following items. Item 1. A composition containing liposomes encapsulating linoleic acid, having a pH of 6.2 to 9.5, and having a Z-average particle size of the liposomes of 90 nm or less. Item 2. The composition according to Item 1, which is a lotion composition. Item 3. The composition according to Item 1 or 2, wherein the content of linoleic acid is 0.01 to 1% by mass based on the total amount of the composition. Item 4. (A) Step: A step of preparing a liposome dispersion encapsulating linoleic acid, (B) Step: A step of preparing a composition that does not contain liposomes encapsulating linoleic acid and contains sodium hydroxide and / or potassium hydroxide, and (C) Step: A step of mixing the liposome dispersion encapsulating linoleic acid prepared in the step (A) with the composition prepared in the step (B). A method for producing a composition containing liposomes encapsulating linoleic acid, comprising the above steps. Item 5. The production method according to item 4, wherein the pH of the composition containing liposomes encapsulating linoleic acid is 6.2 to 9.5. Item 6. The production method according to item 4 or 5, wherein the Z-average particle size of the liposomes encapsulating linoleic acid contained in the composition containing liposomes encapsulating linoleic acid is 90 nm or less. [Effect of the Invention]

[0017] According to the present disclosure, a composition containing liposomes encapsulating linoleic acid can be provided, in which the particle size of the liposomes is relatively small and the skin retention of linoleic acid encapsulated in the liposomes is also excellent. [Brief Description of the Drawings]

[0018]

Figure 1

[0019] Hereinafter, each embodiment included in the present disclosure will be described in more detail. The present disclosure preferably includes, but is not limited to, a composition containing liposomes encapsulating linoleic acid, a method for producing a composition containing liposomes encapsulating linoleic acid, etc., and the present disclosure includes all that is disclosed herein and can be recognized by those skilled in the art.

[0020] 1. Composition of the present disclosure The composition included in the present disclosure contains liposomes encapsulating linoleic acid, has a pH of 6.2 to 9.5, and the Z-average particle size of the liposomes is 90 nm or less. Hereinafter, the composition included in the present disclosure may be referred to as "the composition of the present disclosure". Further, the liposomes encapsulating linoleic acid contained in the composition of the present disclosure may be referred to as "the liposomes of the present disclosure".

[0021] As described above, linoleic acid is a polyunsaturated fatty acid having a whitening effect. The structure of linoleic acid is shown below.

Chemical formula

[0022] The content of linoleic acid in the composition of the present disclosure is not particularly limited as long as the desired effect can be obtained, but may be, for example, 0.0001 to 10% by mass based on the total amount of the composition. If the content of linoleic acid is too low, sufficient whitening effect may not be achieved. On the other hand, if the content of linoleic acid is too high, discoloration and odor change over time may occur. Therefore, the content of linoleic acid is preferably 0.001 to 5% by mass, more preferably 0.01 to 1% by mass, and even more preferably 0.05 to 0.5% by mass based on the total amount of the composition. The upper or lower limit of the above range may be, for example, 0.0001, 0.0005, 0.001, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% by mass.

[0023] In the present disclosure, "liposome" refers to an artificial vesicle having at least one lipid bilayer. Liposomes are classified into multilamellar liposomes (MLV) and unilamellar liposomes based on the number of lipid bilayers. Unilamellar liposomes are further classified into SUV (small unilamella vesicle), LUV (large unilamella vesicle), GUV (giant unilamella vesicle), etc. according to their size. The liposomes of the present disclosure may have any of the above-described structures.

[0024] The liposomes of the present disclosure contain phospholipids, which are amphiphilic substances. Phospholipids have a structure in which fatty acids and phosphoric acid are bonded with glycerin or sphingosine as a central skeleton, and an alcohol is ester-bonded to the phosphoric acid. The phospholipids contained in the liposomes of the present disclosure may be glycerophospholipids having glycerin as a central skeleton, or sphingophospholipids having sphingosine as a central skeleton, but it is preferable to contain at least glycerophospholipids.

[0025] Examples of phospholipids include phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylglycerol, sphingomyelin, etc. Phospholipids are contained in, for example, lecithin. From the viewpoints of easy availability and economy, it is preferable that the liposomes of the present disclosure contain lecithin as a constituent component (especially a membrane constituent component).

[0026] Examples of lecithin include soybean lecithin, egg yolk lecithin, hydrogenated soybean lecithin, hydrogenated egg yolk lecithin, synthetic lecithin, etc. Among these, soybean lecithin and / or egg yolk lecithin are particularly preferable. Also, purified lecithin with increased purity of phospholipids is preferably used. The liposomes of the present disclosure may contain one or more phospholipids and / or lecithin.

[0027] When the composition of the present disclosure contains lecithin, its content is not particularly limited as long as the desired effect can be obtained. For example, it may be 0.01 to 10% by mass based on the total amount of the composition. From the viewpoint of stably encapsulating linoleic acid in liposomes, when the composition of the present disclosure contains lecithin, its content is preferably 0.05 to 5% by mass, more preferably 0.1 to 1% by mass, and even more preferably 0.2 to 0.8% by mass based on the total amount of the composition. The upper or lower limit of the above range may be, for example, 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10% by mass.

[0028] When the composition of the present disclosure contains lecithin, the mass ratio of the content of lecithin to the content of linoleic acid (content of lecithin / content of linoleic acid) is not particularly limited as long as the desired effect can be obtained. For example, it may be 0.5 to 30. From the viewpoint of stably encapsulating linoleic acid in liposomes, the mass ratio of the content of lecithin to the content of linoleic acid is preferably 1 to 20, more preferably 2 to 10, and particularly preferably 2 to 6. The upper or lower limit of the above range may be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30.

[0029] In the present disclosure, the encapsulation of linoleic acid in liposomes means a state in which linoleic acid is included in a structure of lipid vesicles (liposomes) mainly formed of a lipid bilayer membrane. The linoleic acid encapsulated in the liposomes of the present disclosure preferably exists in a state of being enclosed in a space surrounded by the liposome membrane which is a lipid bilayer membrane, but may also exist together with the constituent components of the liposome membrane, may exist between the multiple membranes constituting the multilamellar liposomes, or may exist in a form of adhering or binding to the surface of the outermost membrane among the lipid bilayer membranes constituting the liposomes, and may exist in all or part of them.

[0030] In the technology of the present disclosure, it is sufficient that at least a part of the linoleic acid contained in the composition of the present disclosure is encapsulated in liposomes, and not necessarily all of the linoleic acid needs to be encapsulated in liposomes.

[0031] The pH of the composition of the present disclosure is 6.2 to 9.5. Although not particularly limited, it is preferably 9 or less from the viewpoint of irritation to the skin and the like. The pH of the composition of the present disclosure is preferably 6.2 to 9, more preferably 6.4 to 8.5, and even more preferably 6.6 to 8. The upper or lower limit of the above range may be 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, or 9.5.

[0032] The pH of the composition can be adjusted by known methods or methods that can be easily conceived from known methods. For example, a pH adjuster may be used. Examples of the pH adjuster include citric acid, phosphoric acid, malic acid, pyrophosphoric acid, lactic acid, tartaric acid, glycerophosphoric acid, acetic acid, nitric acid, and chemically possible salts thereof, sodium hydroxide, potassium hydroxide, arginine, triethanolamine, and the like. In the technology of the present disclosure, from the viewpoints of easy availability and economy, it is particularly preferable to adjust the pH of the composition by using at least one pH adjuster selected from the group consisting of citric acid and its salts, sodium hydroxide, and potassium hydroxide.

[0033] The Z-average particle size of the liposomes of the present disclosure is 90 nm or less. Preferably, the Z-average particle size of the liposomes of the present disclosure is 80 nm or less, more preferably 70 nm or less, still more preferably 60 nm or less, and particularly preferably 55 nm or less. The lower limit is not particularly limited, and for example, it may be 10 nm or more. The Z-average particle size of the liposomes of the present disclosure may be, for example, 10 to 90 nm. From the viewpoints of the transparency of the composition, the stability of the liposomes over time, and the skin retention of linoleic acid, etc., the Z-average particle size of the liposomes of the present disclosure is preferably 15 to 80 nm, more preferably 20 to 70 nm, still more preferably 25 to 60 nm, and particularly preferably 30 to 55 nm. The upper or lower limit of the range of the Z-average particle size may be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, or 90 nm.

[0034] Generally, the Z-average particle size of liposomes can be adjusted by known methods or methods that can be easily conceived from known methods. For example, when using a stirrer to prepare a liposome dispersion, the higher the rotation speed of the stirrer and the longer the stirring time, the smaller the Z-average particle size tends to be. When using a high-pressure wet atomization device to prepare a liposome dispersion, the higher the pressure and the more times the fluid passes through the flow path, the smaller the Z-average particle size tends to be.

[0035] When preparing a composition by mixing a dispersion of liposomes encapsulating linoleic acid with water and other components (referred to as "intermediate composition" in this paragraph), adding an alkali such as potassium hydroxide to the intermediate composition and adjusting the pH of the final composition within a specific range (specifically, about pH 6.2 to 9.5), the Z-average particle size of the liposomes encapsulating linoleic acid in the final composition can be made 90 nm or less.

[0036] Generally, the Z-average particle size can be measured and calculated by known methods or methods that can be easily conceived from known methods. For example, it can be measured using a particle size measuring device utilizing light scattering. The Z-average particle size in the present disclosure is the Z-average value calculated from the particle size distribution measured using a particle size measuring device utilizing light scattering. For such measurement and calculation, for example, Zetasizer Nano ZS (Malvern) and the attached software can be used.

[0037] As described above, generally, the larger the particle size of liposomes, the higher the skin retention of the oil-soluble substances encapsulated in the liposomes is considered to be. However, surprisingly, according to the technology of the present disclosure, even when linoleic acid is encapsulated in liposomes with a Z-average particle size of 90 nm or less, the retention of linoleic acid on the skin is achieved, which is equivalent to the case where linoleic acid is encapsulated in liposomes with a Z-average particle size of about 200 nm. That is, according to the technology of the present disclosure, it is possible to achieve the compatibility between the stability of liposomes over time, which has been difficult in the prior art, and the skin retention of linoleic acid encapsulated in liposomes.

[0038] Although not particularly limited, the composition of the present disclosure preferably has a transmittance (which may be simply referred to as "transmittance" in the present disclosure) of 40% or more, more preferably 70% or more, and particularly preferably 80% or more at a measurement wavelength of 600 nm. The upper or lower limit of the above range may be 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85%. The smaller the Z-average particle size of the liposome, the higher the transmittance of the composition tends to be at a measurement wavelength of 600 nm. It should be noted that the lower the transmittance, the cloudier the appearance, and the higher the transmittance, the clearer the appearance.

[0039] Generally, the transmittance can be measured by a known method or a method that can be easily conceived from a known method. For example, it can be measured using a spectrophotometer. The transmittance in the present disclosure is a value measured by ultraviolet-visible spectroscopy (measurement wavelength: 600 nm). For this measurement, for example, an ultraviolet-visible light spectrophotometer UV-2600 (manufactured by Shimadzu Corporation) can be used.

[0040] The composition of the present disclosure may contain known components that can be included in an external composition within a range that does not impair the effects of the present disclosure. Such known components include, for example, water, humectants, oils other than linoleic acid, surfactants, thickeners, film-forming agents, preservatives, chelating agents, antioxidants, coloring agents, fragrances, cooling agents, ultraviolet absorbers, various powders, and known functional components other than linoleic acid used in external compositions. The composition of the present disclosure can optionally contain one or more of these known components.

[0041] Examples of humectants include saccharides such as trehalose, lactulose, and maltitol, sugar alcohols such as sorbitol, mannitol, and maltitol, and polyhydric alcohols such as propanediol, diethylene glycol, polyethylene glycol, 1,3-butylene glycol, glycerin, and diglycerin. Humectants can be used alone or in combination of two or more.

[0042] Examples of oils other than linoleic acid include vegetable oils, triglycerides, waxes, hydrocarbons, higher fatty acids, higher alcohols, esters, silicone oils, and the like. The oils can be used alone or in combination of two or more.

[0043] Examples of surfactants include anionic surfactants such as polyoxyethylene alkyl ether sulfates, alkyl sulfate esters, alkyl amide ether sulfates, polyoxyethylene alkyl amide ether sulfates, α-olefin sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl ether acetates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, higher fatty acid salts, N-acyl amino acid salts, N-acyl isethionates, N-acyl methyl taurates; cationic surfactants such as quaternary ammonium salts; amphoteric surfactants such as amide propyl betaine type, amide amine oxide type, sulfobetaine type, imidazoline type, alkyl betaine type; nonionic surfactants such as polyoxyalkylene alkyl ethers, polyoxyalkylene glycols, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene sorbit fatty acid esters, polyoxyalkylene glycerin fatty acid esters, polyoxyalkylene fatty acid amides, polyoxyalkylene glycol fatty acid esters, polyoxyalkylene castor oil derivatives, polyoxyalkylene hydrogenated castor oil derivatives, polyglycerin fatty acid esters, sorbitan fatty acid esters, sorbit fatty acid esters, sucrose fatty acid esters, alkylene glycol fatty acid esters, alkyl polyglycosides, fatty acid alkanolamides, and the like.

[0044] Examples of thickeners include synthetic polymers such as carboxyvinyl polymer (carbomer), acrylic acid / methacrylic acid alkyl copolymer, sodium polyacrylate; semi-synthetic polymers such as hydroxyethyl cellulose; natural polymers such as xanthan gum and guar gum.

[0045] Examples of the preservative include parabens such as methylparaben, ethylparaben, propylparaben, and butylparaben; benzoic acid; sodium benzoate; phenoxyethanol; and alkyldiaminoethyl glycine hydrochloride.

[0046] Examples of the chelating agent include edetic acid, pentetic acid, metaphosphoric acid, gluconic acid, etidronic acid, or chemically possible salts thereof.

[0047] Examples of the coloring agent include legal dyes such as Food Blue No. 1, Food Yellow No. 4, Food Red No. 202, and Food Green No. 3.

[0048] Examples of the fragrance include menthol, anethole, carvone, eugenol, limonene, wintergreen, ionone, clove oil, rosemary oil, lemon oil, orange oil, osimen oil, citronellol, and methyleugenol.

[0049] Examples of the cooling agent include menthol, spearmint oil, camphor, thymol, and methyl salicylate.

[0050] Examples of the functional components other than linoleic acid include collagen, sodium chondroitin sulfate, tocopherol, tranexamic acid, ascorbic acid and its derivatives, kojic acid, ellagic acid, arbutin, vitamin A compounds, glycyrrhetinic acid, glycyrrhizic acid and its salts, allantoin, isopropylmethylphenol, elastin, and niacinamide.

[0051] Although not particularly limited, the composition of the present disclosure preferably does not contain carboxyvinyl polymer and / or tranexamic acid, and more preferably does not contain carboxyvinyl polymer and tranexamic acid.

[0052] The composition of the present disclosure may be a pharmaceutical composition, a quasi-drug composition, or a cosmetic composition. For example, it may be a skin care agent, a hair care agent, a bath agent, etc. More specifically, it may be lotion, milky lotion, essence, emulsion, cream, ointment, paste, gel, pack, spray, shampoo, conditioner, hair growth agent, scalp lotion, etc.

[0053] As is clear from the above-described Stokes' formula, generally, the higher the kinematic viscosity of the composition, the less likely aggregation of liposomes occurs, and thus the stability of liposomes tends to be higher. However, according to the technology of the present disclosure, liposomes can be stably retained even in a lotion composition or the like having a relatively low kinematic viscosity or almost no viscosity. That is, the technology of the present disclosure can be suitably used also for a composition having a relatively low kinematic viscosity or almost no kinematic viscosity, such as a lotion composition.

[0054] The form of the composition of the present disclosure is not particularly limited, and may be, for example, liquid, cream, gel, paste, semi-solid, solid, powder, etc.

[0055] The application target of the composition of the present disclosure is not particularly limited, but preferably is a human who desires skin whitening, a human who wants to improve the transparency of the skin, etc.

[0056] The matters described in "2. Manufacturing method of the present disclosure" can be applied to the composition of the present disclosure.

[0057] 2. Manufacturing method of the present disclosure The present disclosure also includes a method for manufacturing a composition containing liposomes encapsulating linoleic acid. The said manufacturing method may be referred to as "the manufacturing method of the present disclosure". The matters described regarding the composition of the present disclosure and the liposomes of the present disclosure are applied to the manufacturing method of the present disclosure.

[0058] The manufacturing method of the present disclosure is (A) step: a step of preparing a liposome dispersion encapsulating linoleic acid (B) Step: Preparing a composition that does not contain liposomes encapsulating linoleic acid and contains sodium hydroxide and / or potassium hydroxide, and (C) Step: Mixing the liposome dispersion encapsulating linoleic acid prepared in the above (A) step with the composition prepared in the above (B) step.

[0059] 2-1. Step (A) (A) Step is a step of preparing a liposome dispersion encapsulating linoleic acid. The "liposome dispersion" refers to a liquid in which the water content is less than that of the composition obtained through the (C) step and liposomes are dispersed. The water content in the liposome dispersion is not particularly limited, but for example, it may be 1 to 50% by mass, preferably 3 to 30% by mass, and more preferably 5 to 20% by mass based on the total liposome dispersion. The upper or lower limit of the above range may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50% by mass.

[0060] The liposome dispersion encapsulating linoleic acid can be prepared by a known liposome preparation method or a method that can be easily conceived from a known liposome preparation method. Specifically, for example, a method of mixing linoleic acid, phospholipids, water, and other components using a stirrer such as a disperser or a homomixer can be mentioned. Also, a method of treating after appropriately mixing linoleic acid, phospholipids, water, and other components using a high-pressure wet atomization device can be mentioned. The rotation speed, rotation number (rpm), and stirring time of the stirrer, as well as the pressure and number of passes through the flow path of the high-pressure wet atomization device, can be appropriately adjusted based on ordinary knowledge in the technical field.

[0061] Although not particularly limited, in the technology of the present disclosure, it is particularly preferable that the liposome dispersion encapsulating linoleic acid is prepared using a high-pressure wet atomization device. Specific examples of the high-pressure wet atomization device include STAR BURST (manufactured by Sugino Machine, Ltd.) and the like.

[0062] 2-2. Step (B) (B) The step is a step of preparing a composition (which may be referred to as the “intermediate composition in step (B)” in the present disclosure) that does not contain liposomes encapsulating linoleic acid and contains sodium hydroxide and / or potassium hydroxide. The method for preparing the intermediate composition in step (B) is not particularly limited, and for example, it can be prepared by mixing sodium hydroxide and / or potassium hydroxide, water, and other components.

[0063] 2-3. Step (C) (C) The step is a step of mixing the liposome dispersion encapsulating linoleic acid prepared in the above (A) step with the composition (intermediate composition in step (B)) prepared in the above (B) step. The mixing method is not particularly limited. For example, the liposome dispersion may be added to the intermediate composition in step (B) and stirred, or the intermediate composition in step (B) may be added to the liposome dispersion and stirred.

[0064] 2-4. Others The matters described in “1. The composition of the present disclosure” can be incorporated into the manufacturing method of the present disclosure. Further, in the manufacturing method of the present disclosure, appropriate heating may be performed at any timing. Furthermore, a step of adjusting the pH of the composition may be performed after step (C). In this case, the pH is preferably adjusted to 6.2 or higher.

[0065] In addition, as used herein, the term “comprising” includes, in addition to “containing,” “essentially consisting of” and “consisting of” (The term “comprising” includes “essentially consisting of” and ”consisting of.“). Further, the present disclosure encompasses all arbitrary combinations of the constituent elements described in this specification.

[0066] In addition, various characteristics (properties, numerical values, functions, etc.) described for each embodiment of the present disclosure above may be combined in any manner in identifying the subject matter encompassed by the present disclosure. That is, the present disclosure encompasses all subject matter consisting of any combination of the combinable characteristics described herein.

Example

[0067] Hereinafter, embodiments of the present disclosure will be described more specifically with examples, but the embodiments of the present disclosure are not limited to the following examples. Unless otherwise specified, % indicates mass % in the context of the composition.

[0068] 1. Preparation of liposomes 1-1. Preparation of rice bran oil-encapsulated liposome dispersion (Reference Example) According to the composition in the following table, a rice bran oil encapsulated liposome dispersion was prepared. In this example, polyoxyethylene hydrogenated castor oil with an average added mole number of ethylene oxide of 60 is simply referred to as "polyoxyethylene hydrogenated castor oil".

[0069]

Table 1

[0070] More specifically, among the components in the above table, the components other than potassium hydroxide and purified water (Phase 1) were added to a beaker, heated to 80 °C, and stirred until uniform. Potassium hydroxide and purified water (Phase 2) were added to another beaker and mixed, and then heated to 80 °C. While continuing the heating and stirring of Phase 1, Phase 2 heated to 80 °C was added. Thereafter, high-pressure treatment was performed at 200 MPa using a high-pressure wet atomization device (STAR BURST: Sugino Machine Co., Ltd.) to prepare a rice bran oil encapsulated liposome dispersion.

[0071] 1-2. Preparation of linoleic acid-encapsulated liposome dispersion According to the composition in the following table, a linoleic acid encapsulated liposome dispersion was prepared.

[0072]

Table 2

[0073] More specifically, among the components in the above table, those in Phase 1 were added to a beaker and stirred until uniform, and then high-pressure treatment was performed at 100 MPa using a high-pressure wet atomization device (STAR BURST: manufactured by Sugino Machine Ltd.). Xanthan gum, 1,3-butylene glycol, and purified water (Phase 2) were added to a beaker separate from the above beaker and stirred until uniform. The high-pressure-treated Phase 1 and Phase 2 were mixed until uniform to prepare a linoleic acid-encapsulated liposome dispersion.

[0074] 2. Preparation and evaluation of lotion containing liposomes 2-1. Lotion containing rice bran oil-encapsulated liposomes (Reference Example) 2-1-1. Preparation of lotion containing rice bran oil-encapsulated liposomes According to the composition in the following table, a lotion containing rice bran oil-encapsulated liposomes was prepared.

[0075]

Table 3

[0076] More specifically, among the components in the above table, components other than the rice bran oil-encapsulated liposome dispersion and 10% aqueous potassium hydroxide solution (which may be denoted as 10% aq potassium hydroxide) in Phase 1 were added to a beaker and stirred until uniform. The rice bran oil-encapsulated liposome dispersion (Phase 2) prepared in Test Example 1-1 was added to the beaker and stirred until uniform to prepare a lotion. When the pH of the lotion was measured before adding the 10% aqueous potassium hydroxide solution, it was 5.72 (Reference Example 1). Thereafter, the 10% aqueous potassium hydroxide solution (Phase 3) was added to adjust to each pH described in the table (Reference Examples 2 to 5). In each of the prepared lotions, no separation, precipitation, aggregation, etc. were observed, and they had a translucent and uniform appearance.

[0077] 2-1-2. Evaluation of lotion containing rice bran oil-encapsulated liposomes The transmittance at a measurement wavelength of 600 nm of each rice bran oil-encapsulated liposome-containing lotion prepared in Test Example 2-1-1 (which may be referred to as "600 nm transmittance" in this test example) was measured using an ultraviolet-visible spectrophotometer UV-2600 (manufactured by Shimadzu Corporation).

[0078] Also, the Z-average particle size of the liposomes in each rice bran oil-encapsulated liposome-containing lotion prepared in Test Example 2-1-1 was measured. Specifically, each rice bran oil-encapsulated liposome-containing lotion was diluted 100-fold with purified water to obtain a measurement sample. The particle size distribution of the liposomes in the measurement sample was measured using a Zetasizer Nano ZS (manufactured by Malvern). The Z-average particle size was determined from the measured particle size distribution using analysis software "Zetasizer software (manufactured by Malvern)".

[0079] The above results are shown in the following table. The criteria for judging the 600 nm transmittance are as follows: transmittance of 70% or more: ◎, 40% or more and less than 70%: ○, less than 40% or separation: ×. The criteria for judging the Z-average particle size are as follows: Z-average particle size of 60 nm or less: ◎, more than 60 nm and 100 nm or less: ○, more than 100 nm: ×. The criteria for comprehensive judgment are as follows: both the 600 nm transmittance judgment and the Z-average particle size judgment are ◎: ◎, among the 600 nm transmittance judgment and the Z-average particle size judgment, there is one or more ○ judgments and no × judgment: ○, among the 600 nm transmittance judgment and the Z-average particle size judgment, there is one or more × judgments: ×.

[0080]

Table 4

[0081] 2-1-3. Parentheses As described above, in each rice bran oil-encapsulated liposome-containing lotion prepared in Test Example 2-1-1, separation, precipitation, aggregation, etc. were not observed, and the appearance was uniform. Also, the 600 nm transmittance was relatively high and the Z-average particle size was relatively small in each lotion.

[0082] From the Stokes' equation, it is considered that the smaller the particle size of the liposome, the higher the temporal stability of the liposome-containing composition. Therefore, from the results of this test example, it was suggested that excellent temporal stability of liposomes was exhibited in the rice bran oil-encapsulated liposome-containing composition regardless of pH.

[0083] 2-2. Lotion containing linoleic acid-encapsulated liposomes (1) 2-2-1. Preparation of lotion containing linoleic acid-encapsulated liposomes (1) A lotion containing linoleic acid-encapsulated liposomes was prepared according to the composition in the following table.

[0084]

Table 5

[0085] More specifically, among the components in the above table, components other than the linoleic acid-encapsulated liposome dispersion and 10% aqueous potassium hydroxide solution (Phase 1) were added to a beaker and stirred until uniform. The linoleic acid-encapsulated liposome dispersion (Phase 2) prepared in Test Example 1-2 was added to the beaker and stirred until uniform to prepare a lotion. When the pH of the lotion was measured before adding the 10% aqueous potassium hydroxide solution, it was 5.75 (Comparative Example 1). Thereafter, a 10% aqueous potassium hydroxide solution (Phase 3) was added and adjusted to each pH described in the table (Comparative Examples 2 to 5). In Comparative Examples 1 and 2, obvious separation was observed in appearance within one week from the preparation. Comparative Examples 3 to 5 had a turbid appearance.

[0086] 2-2-2. Evaluation of lotion containing linoleic acid-encapsulated liposomes (1) The transmittance at a measurement wavelength of 600 nm of each lotion containing linoleic acid-encapsulated liposomes prepared in Test Example 2-2-1, and the Z-average particle size of the liposomes in the lotion were measured by the method described in Test Example 2-1-2. However, for Comparative Examples 1 and 2 in which obvious separation was observed in appearance, the transmittance was not measured. Also, the Z-average particle sizes of Comparative Examples 1 and 2 were measured immediately after preparation and before separation occurred.

[0087] The results are shown in the following table. Note that each criterion is the same as in Test Example 2-1-2.

[0088]

Table 6

[0089] 2-2-3. Parentheses As described above, in each of the lotion containing linoleic acid-encapsulated liposomes prepared in Test Example 2-2-1, liposomes with a small particle size could not be obtained, and in some cases, separation occurred. From the results, it was suggested that each of the lotions containing linoleic acid-encapsulated liposomes prepared in Test Example 2-2-1 had poor stability over time. That is, it was suggested that a composition containing liposomes encapsulating linoleic acid with excellent stability over time could not be obtained by the same method as the rice bran oil-encapsulated liposomes.

[0090] Therefore, the present inventors examined a method for preparing a composition containing liposomes encapsulating linoleic acid and having a relatively small particle size.

[0091] 2-3. Lotion containing linoleic acid-encapsulated liposomes (2) 2-3-1. Preparation of lotion containing linoleic acid-encapsulated liposomes (2) According to the composition in the following table, a lotion containing linoleic acid-encapsulated liposomes was prepared.

[0092]

Table 7

[0093] For Comparative Examples 7 and 8 and Examples 1 to 7, before adding the linoleic acid-encapsulated liposome dispersion to the beaker into which Phase 1 had been put, a 10% aqueous potassium hydroxide solution (Phase 2) was added, and the mixture was stirred until it became uniform. The linoleic acid-encapsulated liposome dispersion (Phase 3) prepared in Test Example 1-2 was added to the beaker, and the mixture was stirred until it became uniform to prepare a lotion. For Examples 6 and 7 and Comparative Example 8 in which the final pH was 8 or higher, after adding the linoleic acid-encapsulated liposome dispersion and stirring until it became uniform, a 10% aqueous potassium hydroxide solution (Phase 4) was further added to adjust to each pH described in the table.

[0094] In Comparative Examples 6 to 8, obvious separation was observed in terms of appearance within one week from the preparation. On the other hand, in Examples 1 to 7, separation, precipitation, aggregation, etc. were not observed, and the appearance was uniform, semi-transparent to cloudy white.

[0095] 2-3-2. Evaluation of lotion containing linoleic acid-encapsulated liposomes (2) The transmittance at a measurement wavelength of 600 nm of each lotion containing linoleic acid-encapsulated liposomes prepared in Test Example 2-3-1 and the Z-average particle size of the liposomes in the lotion were measured by the method described in Test Example 2-1-2. However, for Comparative Examples 6 to 8 in which obvious separation was observed in terms of appearance, the transmittance was not measured. Also, the Z-average particle sizes of Comparative Examples 6 to 8 were measured immediately after the preparation, before separation occurred.

[0096] The results are shown in the table below. Note that each criterion is the same as in Test Example 2-1-2.

[0097]

Table 8

[0098] 2-3-3. Parentheses From the above test examples, it was found that by adding an alkali such as potassium hydroxide to the intermediate composition (referred to as the intermediate composition in this test example) before mixing the linoleic acid-encapsulated liposome dispersion with a mixture of water and other components (such as water), and adjusting the pH of the final composition within a specific range (specifically, about pH 6.2 to 9.5), a composition containing linoleic acid-encapsulated liposomes with relatively high transparency and relatively small Z-average particle size of the contained liposomes can be obtained.

[0099] As described above, since it is considered that the smaller the particle size of the liposome, the higher the stability of the liposome-containing composition over time, it was suggested that excellent stability of the liposome over time is exhibited in the linoleic acid-encapsulated liposome-containing composition obtained by the above method.

[0100] 3. Evaluation of skin retention of linoleic acid As described above, while the smaller the particle size of the liposome, the more likely the stability of the liposome over time is to improve, on the other hand, the larger the particle size of the liposome, the higher the skin retention of the oil-soluble substance encapsulated in the liposome is considered to be. In Test Example 2, the inventors found a technique for providing a composition containing linoleic acid-encapsulated liposomes with a relatively small Z-average particle size of the liposome. Therefore, next, the inventors evaluated the skin retention of linoleic acid encapsulated in the liposome.

[0101] 3-1. Evaluation target In this test example, the linoleic acid-encapsulated liposome dispersion obtained in Test Examples 1-2 was used as the evaluation target. When the Z-average particle size of the liposomes in the liposome dispersion was measured, it was 45.9 nm. Hereinafter, in this test example, the linoleic acid-encapsulated liposome dispersion obtained in Test Examples 1-2 may be referred to as "50 nm liposomes".

[0102] In addition, as a comparison target, the inventors used a linoleic acid-encapsulated liposome dispersion with a Z-average particle size of about 200 nm. The composition of the linoleic acid-encapsulated liposome dispersion was the same as that in Test Example 1-2. When the Z-average particle size of the liposomes in the liposome dispersion was measured, it was 218 nm. Hereinafter, in this test example, the linoleic acid-encapsulated liposome dispersion may be referred to as "200 nm liposome".

[0103] In addition, skin lotions were prepared using the above 50 nm liposomes and 200 nm liposomes, and when the Z-average particle size of the liposomes in the skin lotions was measured, they were 43.7 nm and 191.7 nm, respectively. The composition, pH, and Z-average particle size of the liposomes contained in the skin lotion are shown in the following table. The skin lotion was prepared in the same manner as in Test Example 2-3-1.

[0104]

Table 9

[0105] 3-2. Evaluation method The evaluation was carried out by modifying the method described in "Guidance for Using In vitro Skin Permeation Test (In vitro Percutaneous Absorption Test) for the Safety Evaluation of Cosmetics and Quasi-Drugs" (Notification No. 1115 of the Pharmaceutical and Food Safety Bureau, Ministry of Health, Labour and Welfare, dated November 15, 2016, attached to the notice from the Director of the Pharmaceutical Affairs and Sanitation Division of each prefectural government to the Director of the Pharmaceutical Review and Management Section of the Pharmaceutical and Food Safety Bureau, Ministry of Health, Labour and Welfare). Specifically, the following operations were performed for each of the 50 nm liposomes and 200 nm liposomes. The evaluation was carried out with n = 3.

[0106] As human skin, TRA2T series: Frozen Human Dermatomed skin OECD Guideline Compliant (BIOPREDIC International) was used. The thickness of the human skin used in this test example was 322 μm. As the buffer (receptor solution), PBS(-) containing 1% BSA (BSA: bovine serum albumin, fatty acid free, Nacalai Tesque, PBS(-): for cell culture, Fujifilm Wako Pure Chemical Corporation) was used. The human skin was set in a static Franz cell filled with the buffer and allowed to stand in an incubator at 32 ± 1 °C until it reached thermal equilibrium. The area of the effective permeation site of the static Franz cell was 64 mm 2 (circular with a diameter of 9 mm). Then, 100 mg of 50 nm liposomes or 200 nm liposomes was spread on the surface of the human skin and allowed to stand in an incubator at 32 ± 1 °C for 4 hours.

[0107] After 4 hours, the skin surface was wiped with a cotton swab, and the stratum corneum was removed by tape stripping twice. Skin was punched out from the human skin with the stratum corneum removed using a punch with a diameter of 10 mm. Linoleic acid was extracted from the punched-out skin using 50 mL of methanol, and the extracted linoleic acid was quantified by HPLC and LC / MS.

[0108] 3-3. Results The results are shown in Figure 1. As understood from the above evaluation method, the linoleic acid quantified in this test example reflects the amount of linoleic acid that permeated from the stratum corneum to the inside of the skin but did not diffuse into the receptor solution, that is, the amount of linoleic acid retained inside the skin.

[0109] As described above, generally, it is considered that the smaller the particle size of the liposome, the less likely the liposome is to remain inside the skin. However, unexpectedly in this test example, there was no significant difference in the amount of linoleic acid extracted and quantified from the skin between the 50 nm liposome and the 200 nm liposome. That is, it was suggested that even in the case of the 50 nm liposome with a relatively small particle size, a high skin retention of linoleic acid equivalent to that of the 200 nm liposome was achieved.

[0110] 4. Summary As described above, generally, while the smaller the particle size of the liposome, the more likely the stability of the liposome over time tends to improve, on the other hand, the larger the particle size of the liposome, the higher the skin retention of the liposome is considered to be. For this reason, it has been difficult in the prior art to achieve both the stability of the liposome over time and the skin retention of the linoleic acid encapsulated in the liposome.

[0111] From the examples of the present disclosure, according to a composition containing a liposome encapsulating linoleic acid, having a pH of 6.2 to 9.5, and having a Z-average particle size of the liposome of 90 nm or less, it was suggested that a composition containing a liposome encapsulating linoleic acid, which is excellent in the stability of the liposome over time and also excellent in the skin retention of the linoleic acid encapsulated in the liposome, is provided.

Claims

1. A composition comprising liposomes encapsulating linoleic acid, having a pH of 6.2 to 9.5, and having a Z-average particle size of the liposomes of 90 nm or less.

2. The composition according to claim 1, which is a lotion composition.

3. The composition according to claim 1 or 2, wherein the content of linoleic acid is 0.01 to 1% by mass based on the total amount of the composition.

4. Step (A): A step of preparing a liposome dispersion encapsulating linoleic acid, Step (B): A step of preparing a composition containing no liposomes encapsulating linoleic acid and containing sodium hydroxide and / or potassium hydroxide, and Step (C): A step of mixing the liposome dispersion encapsulating linoleic acid prepared in step (A) with the composition prepared in step (B) A method for producing a composition containing liposomes encapsulating linoleic acid, comprising the steps of:

5. The production method according to claim 4, wherein the pH of the composition containing liposomes encapsulating linoleic acid is 6.2 to 9.

5.

6. The production method according to claim 4 or 5, wherein the Z-average particle size of the liposomes encapsulating linoleic acid contained in the composition containing liposomes encapsulating linoleic acid is 90 nm or less.

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