Antibacterial agent

Abstract

To provide a novel topical agent with excellent antibacterial properties.SOLUTION: Provided is an antibacterial agent characterized by containing an extract of melilot cultivated under irradiation with light with a photosynthetic photon flux density (PPFD) ratio of 4:1 to 2:1 between the wavelength ranges of 570 to 730 nm and 400 to 515 nm, using one or more solvents selected from water, lower alcohols, and liquid polyhydric alcohols.EFFECT: The specific melilot extract of the present invention has an excellent selective antibacterial effect that can suppress harmful bacteria while leaving beneficial bacteria for the skin, and is also excellent in stability, making it expected to be used in health materials, cosmetics, quasi-drugs, pharmaceuticals, and the like.SELECTED DRAWING: None

Description

TECHNICAL FIELD

[0001] The present invention relates to an antibacterial agent capable of suppressing harmful bacteria while leaving bacteria beneficial to the skin.

BACKGROUND ART

[0002] Various microorganisms called skin resident bacteria inhabit the surface of healthy human skin, forming a skin resident bacterial flora. Although there are individual differences and site differences, etc., the skin resident bacterial flora is composed of various microorganisms, and examples include bacteria such as Cutibacterium acnes (C. acnes) and Staphylococcus epidermidis (S. epidermidis), and fungi such as Malassezia genus yeasts including Malassezia restricta (M. restricta) and Malassezia sympodialis (M. sympodialis).

[0003] Skin resident bacteria usually form part of the sebum film and play a beneficial role for humans. An example is the elimination of pathogenic bacteria. Healthy skin is weakly acidic, and the pH of the skin is regulated by various factors such as lactic acid contained in sweat in sebum, which also includes skin resident bacteria. For example, Cutibacterium acnes decomposes neutral fat (triglyceride) in sebum, assimilates the generated glycerin, and produces propionic acid and acetic acid as metabolites, and these actions keep the skin weakly acidic at a pH of about 5.0 to 5.5. On the other hand, Staphylococcus aureus, which is a pathogenic bacterium, has an optimal growth pH of neutral, so its growth is suppressed on skin kept weakly acidic. In addition, glycerin generated by the decomposition of neutral fat by skin resident bacteria serves as a natural moisturizing component that keeps the skin hydrated. However, when specific skin resident bacteria overproliferate for some reason, various skin diseases are caused. It can be said that understanding and controlling skin resident bacteria is important for maintaining skin health.

[0004] Propionibacterium acnes is the most dominant bacterium on human skin (Non-Patent Literature 1). Propionibacterium acnes uses sebum secreted from human sebaceous glands as a nutrient source, and due to its anaerobic nature, it is said to reside in large numbers deep within sebaceous hair follicles (hair follicles with well-developed sebaceous glands). Propionibacterium acnes is considered to be the causative agent of acne (acne vulgaris). When hair follicles are blocked, they become anaerobic, allowing Propionibacterium acnes to proliferate actively. Propionibacterium acnes breaks down sebum with lipase, and the resulting free fatty acids trigger inflammation. It is also thought that the human body's innate immune response to Propionibacterium acnes is involved in acne inflammation (Non-Patent Literature 2).

[0005] Staphylococcus epidermidis can be considered a competitor of Propionibacterium acnes. There are multiple reports that Staphylococcus epidermidis inhibits the growth of Propionibacterium acnes (Non-Patent Literature 3, 4). In other words, it is desirable to maintain a healthy population of Staphylococcus epidermidis to prevent the excessive growth of Propionibacterium acnes. Furthermore, Staphylococcus epidermidis is said to enhance resistance to pathogenic bacteria by promoting the expression of antimicrobial peptides. In addition, there are reports that Staphylococcus epidermidis contributes to skin hydration by breaking down sebum and producing glycerin, a natural moisturizer, and it is considered a beneficial bacterium for humans (Non-Patent Literature 5).

[0006] Malassezia restricta is said to be a fungus deeply involved in seborrheic dermatitis and atopic dermatitis (Non-patent documents 6, 7). It breaks down sebum with lipase, and the resulting free fatty acids trigger inflammation. In addition, it is thought that the human innate immune response to Malassezia restricta is involved in acne inflammation.

[0007] On the other hand, although Malassezia sympodialis grows on human skin, there have been no reports of it causing skin diseases. As it belongs to the same Malassezia genus, it is presumed to compete with Malassezia restricta in terms of habitat and nutrient sources such as sebum, and can be considered a beneficial fungus for humans.

[0008] While commensal skin bacteria are beneficial, coexisting with humans and protecting their skin when the balance of each bacterium is maintained, excessive proliferation of certain bacteria can cause skin diseases. Therefore, maintaining an appropriate balance of bacteria is crucial. Currently, however, while nadifloxacin and benzoyl peroxide are commonly used as antibacterial agents against bacteria, they exhibit antibacterial activity not only against acne bacteria but also against Staphylococcus epidermidis, making it difficult to achieve selective antibacterial action. Similarly, while ketoconazole and luliconazole are commonly used against fungi, it is difficult to achieve selective antibacterial action against specific Malassezia species. There is a need for antibacterial agents that can suppress harmful bacteria while preserving beneficial bacteria for the skin. In the past, materials and components that exhibit antibacterial activity only against specific bacterial species have been investigated (Patent Documents 1-4). However, it is difficult to say that there are sufficient materials or components that can reduce harmful bacteria while preserving beneficial bacteria for the skin, for both bacteria and fungi.

[0009] Melilotus officinalis is a perennial herb belonging to the genus Melilotus in the legume family. Melilotus is known to have skin-whitening effects (Patent Document 5) and collagen production-promoting effects (Patent Document 6). However, its antibacterial properties are unknown. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2021-161043 [Patent Document 2] Japanese Patent Publication No. 2014-062059 [Patent Document 3] Japanese Patent Publication No. 2018-150266 [Patent Document 4] Japanese Patent Publication No. 2013-249293 [Patent Document 5] Japanese Patent Application Publication No. 05-163115 [Patent Document 6] Japanese Patent Publication No. 2008-024622 [Non-Patent Document 1] J Invest Dermatol,Vol.133(9),PP.2152-2160(2013) [Non-Patent Document 2] "Evolving Acne Management," Nakayama Shoten, pp. 103-108 (2012) [Non-Patent Document 3] Appl Microbiol Biotechnol,Vol.98(1),PP.411-424(2014) [Non-Patent Document 4] Exp Dermatol,Vol.26(9),PP.798-803(2017) [Non-Patent Document 5] Immunity,Vol.42,PP.756-766(2015) [Non-Patent Document 6] Journal of the Japanese Society for Medical Mycology, Vol. 46(3), pp. 163-167 (2005) [Non-Patent Document 7] Journal of the Japanese Society for Medical Mycology, Vol. 53(2), pp. 97-102 (2012) [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] There is a demand for materials that are highly safe, possess selective antibacterial properties that suppress harmful bacteria while preserving beneficial bacteria on the skin, but currently, such materials are not yet available that fully satisfy the needs of the skin. [Means for solving the problem]

[0012] Under such circumstances, as a result of intensive studies by the present inventors, it has been found that an extract of melilot cultivated by irradiation with two types of artificial light having specific wavelength ranges has excellent selective antibacterial properties that can suppress harmful bacteria while retaining beneficial bacteria for the skin. Specifically, the present inventors have found the effect of selectively inhibiting the growth of Cutibacterium acnes and Malassezia restricta, which exert harmful effects on humans due to overproliferation. Furthermore, the present inventors have found that an external preparation containing the extract can be a health material, cosmetic, quasi-drug or pharmaceutical product having selective antibacterial properties capable of suppressing harmful bacteria while retaining beneficial bacteria for the skin, and the present invention has been completed.

[0013] That is, the present invention includes the following inventions.

[0014] (1) An antibacterial agent comprising an extract of melilot cultivated by irradiation with light having a photosynthetic photon flux density (PPFD) ratio of 4:1 to 2:1 between the wavelength ranges of 570 to 730 nm and 400 to 515 nm, wherein the extract is obtained using one or two or more solvents selected from water, lower alcohols and liquid polyhydric alcohols. (2) An antibacterial agent comprising an extract of melilot cultivated by irradiation with light having a photosynthetic photon flux density (PPFD) ratio of 8:1 to 1:1 between the wavelength ranges of 570 to 730 nm and 400 to 515 nm, wherein the extract is obtained using one or two or more solvents selected from water, lower alcohols and liquid polyhydric alcohols. (3) The antibacterial agent according to (1) or (2), which exhibits antibacterial activity against Cutibacterium acnes. (4) The antibacterial agent according to (1) or (2), which exhibits antibacterial activity against Malassezia restricta. (5) An acne inhibitor comprising the melilot extract according to (1) or (2). (6) A seborrheic dermatitis inhibitor comprising the melilot extract according to (1) or (2). (7) An atopic dermatitis inhibitor comprising the melilot extract according to (1) or (2). [Effects of the Invention]

[0015] According to the present invention, a selective antibacterial agent is provided that contains an extract of sweet clover cultivated under irradiation with two types of artificial light having specific wavelength ranges as an active ingredient, which can suppress harmful bacteria while leaving beneficial bacteria on the skin. [Modes for carrying out the invention]

[0016] The Melilotus officinails used in this invention is also known as Shinagawahagi or Seiyoebirahagi, and is a perennial plant belonging to the genus Melilotus in the family Fabaceae. In this invention, the Melilotus extract refers to an extract of a part of the plant such as its flowers, seeds, leaves, stems, or roots, or the entire plant (whole plant), or a mixture thereof. However, in this invention, the part used as the raw material for extraction is preferably the leaves. Furthermore, the plant may be used as is for extraction, or it may be processed by drying, crushing, or finely chopping.

[0017] Cultivation methods include soil cultivation and hydroponics. When using hydroponics, the seeds can be used after they have rooted. Cultivation is preferably carried out in a facility where temperature, light, and carbon dioxide concentration are controlled. The cultivation temperature is 15-30°C, preferably 20-25°C. The cultivation period varies depending on the irradiation conditions, but harvesting is generally possible in 10-30 days. Cultivation for longer periods is also possible.

[0018] The light source can be a light source used in plant cultivation facilities, with artificial light such as LEDs being the most preferred. Examples of artificial light include light-emitting diodes (LEDs) and laser diodes, but any light source that can selectively emit light within a specific range of wavelengths is acceptable.

[0019] In cultivating sweet clover, the wavelengths of light to be irradiated are preferably blue light in the wavelength range of 400-515 nm and red light in the wavelength range of 570-730 nm, and more preferably light in the wavelength range of 430-460 nm and 630-680 nm. It is most preferable to irradiate with these lights simultaneously. The wavelengths in question refer to the maximum wavelengths (peak wavelengths) of the irradiation spectrum. Any light source having peaks at such wavelengths can be used, whether it is a custom-made or commercially available one. Optical filters may also be used to selectively irradiate with the above wavelengths. In addition to the two types of light mentioned above, light sources such as sunlight and fluorescent lamps can also be used.

[0020] The amount of light irradiated is expressed as photosynthetic photon flux density (PPFD). When two types of light-emitting devices are used for irradiation, it refers to the total amount of light emitted. This amount of light is 10-300 μmol·m³ after germination. -2 s -1 Preferably, 50-200 μmol·m -2 s -1 This is even more preferable. If the light intensity is outside this range, growth disorders or poor growth may occur. Irradiation is preferably done from a position 10 to 50 cm above the melilot. The irradiation time can be appropriately changed depending on the characteristics and purpose of the plant, but 6 hours or more is preferable, and 12 to 24 hours is more preferable.

[0021] The ratio of red to blue light intensity refers to the ratio of each PPFD, and can be selected according to the purpose, such as yield or effectiveness.

[0022] In particular, to increase plant yield, a ratio of red to blue light intensity of 8:1 to 1:1 is preferable, with 4:1 to 2:1 being more preferable, and 3:1 being the most preferable.

[0023] The extraction method is not particularly limited, but can be carried out by using water or hot water, or a mixed solvent of water and an organic solvent, and by stirring or column extraction. Examples of extraction solvents include water, lower alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, etc.), liquid polyhydric alcohols (1,3-butylene glycol, propylene glycol, glycerin, etc.), ketones (acetone, methyl ethyl ketone, etc.), acetonitrile, esters (ethyl acetate, butyl acetate, etc.), hydrocarbons (hexane, heptane, liquid paraffin, etc.), and ethers (ethyl ether, tetrahydrofuran, propyl ether, etc.). Preferably, polar solvents such as water, lower alcohols, and liquid polyhydric alcohols are used, and particularly preferably, water, ethanol, 1,3-butylene glycol, and propylene glycol are used. These solvents may be used individually or in combination of two or more. Particularly preferred extraction solvents include water, a mixed polar solvent of water and ethanol, or a mixed polar solvent of water and 1,3-butylene glycol.

[0024] There are no particular limitations on the amount of solvent used; for example, it should be 10 times or more, preferably 20 times or more, relative to the dry weight of the Melilot leaves. However, for convenience in operations such as concentration or isolation after extraction, it is preferable to use 100 times or less. The extraction temperature and time can be appropriately selected depending on the type of solvent used and the pressure during extraction.

[0025] The above extract may be used as is, but if necessary, it may be used after treatment such as concentration (concentration by vacuum concentration, membrane concentration, etc.), dilution, filtration, decolorization with activated carbon, deodorization, ethanol precipitation, etc., to the extent that the effects of the present invention are achieved. Furthermore, the extracted solution may be treated by concentration to dryness, spray drying, freeze-drying, etc., and used as a dried product.

[0026] Furthermore, the extract obtained using the above-mentioned extractant may contain ingredients used in cosmetics, quasi-drugs, or pharmaceuticals, such as oils and fats, waxes, hydrocarbons, fatty acids, alcohols, esters, surfactants, metal soaps, pH adjusters, preservatives, fragrances, humectants, powders, UV absorbers, thickeners, pigments, antioxidants, whitening agents, chelating agents, excipients, and film-forming agents, to the extent that they do not impair the effectiveness of the extract.

[0027] The present invention can be used in cosmetics, quasi-drugs, and pharmaceuticals, and its dosage forms include, for example, lotions, creams, emulsions, gels, aerosols, essences, packs, cleansers, bath products, foundations, powders, ointments, poultices, and the like.

[0028] For external use, the content of the above extract used in this invention is preferably 0.0001% by weight or more, more preferably 0.001 to 10% by weight, when converted to solid matter. Furthermore, 0.01 to 5% by weight is most preferable. Below 0.0001% by weight, sufficient effect is unlikely to be expected. Above 10% by weight, enhancement of effect is unlikely to be observed, and it is uneconomical.

[0029] Next, in order to describe the present invention in detail, examples of the production, formulation, and experimentation of the extract used in the present invention will be given as examples, but the present invention is not limited thereto. The percentages shown in the production and formulation examples are weight percentages. [Examples]

[0030] (1) Experimental materials and growth conditions Melilot seeds were sown in moist vermiculite, germinated at room temperature (22-25°C) in the dark, and then grown as seedlings at 22-26°C under fluorescent lighting. Subsequently, the young shoots were wrapped in sponges and grown in a hydroponic system at room temperature (21-25°C) for 24 hours. Red LEDs (peak wavelength 660nm) and blue LEDs (peak wavelength 450nm) were simultaneously irradiated from 30cm directly above the plants, resulting in a total photosynthetic photon flux density of 100 μmol·m³ from the red and blue LEDs. -2 s -1To achieve this, cultivation was carried out with a light intensity ratio of 8:1 to 1:1 for red and blue light. The light intensity ratio was not changed during cultivation. Cultivation was also carried out under sunlight. In both cases, after cultivation for 4 weeks, the plants were harvested and dried by hot air drying at approximately 60°C to obtain dried melilot (Table 1).

[0031] [Table 1]

[0032] (2) Example of production of melilot extract The melilot extract was prepared as follows. In preparation examples 1A to 4A, the melilot leaves used as the extraction material were grown under conditions where the ratio of red to blue light intensity was 2:1.

[0033] (Production Example 1A) Preparation of hot water extract of Melilot 10 g of dried melilot was added to 200 mL of water and extracted at 95-100°C for 2 hours. The resulting extract was filtered, the filtrate was concentrated, and freeze-dried to obtain 2.6 g of hot water extract of melilot.

[0034] (Production Example 2A) Preparation of a 50% ethanol extract of Melilot 10 g of dried melilot was immersed in 200 mL of 50% ethanol aqueous solution at room temperature for 7 days to extract the extract. After filtering the resulting extract, it was concentrated to dryness using an evaporator to obtain 2.1 g of 50% ethanol extract of melilot.

[0035] (Production Example 3A) Preparation of ethanol extract of Melilot 10 g of dried melilot was immersed in 200 mL of ethanol at room temperature for 7 days to extract the extract. After filtering the resulting extract, it was concentrated to dryness using an evaporator to obtain 0.55 g of melilot ethanol extract.

[0036] (Preparation Example 4A) Preparation of 1,3-butylene glycol extract of Melilot 10 g of dried Melilotus was immersed in 200 mL of 1,3-butylene glycol at room temperature for 7 days to extract the extract. The resulting extract was filtered to obtain 195 g of Melilotus 1,3-butylene glycol extract.

[0037] Similarly, the total photosynthetic photon flux density of red and blue LEDs is 100 μmol·m. -2 s -1 To achieve this, we used melilots cultivated with varying ratios of red and blue light, and melilots cultivated under sunlight, and extracted them in the same manner as in production examples 1A to 4A above, resulting in production examples 1B to 4B, 1C to 4C, and production examples P to S (Table 2).

[0038] [Table 2] [Examples]

[0039] (Example prescription 1) Lotion Formula Content (%) 1. Hot water extract of Melilot (Production Example 1B) 2.0 2,1,3-Butylene glycol 8.0 3. Glycerin 2.0 4. Xanthan gum 0.02 5. Citric acid 0.01 6. Sodium citrate 0.1 7. Ethanol 5.0 8. Methyl parahydroxybenzoate 0.1 9. Polyoxyethylene hydrogenated castor oil (40 E.O.) 0.1 10.Fragrance (appropriate amount) 11. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Components 1-6 and 11 and components 7-10 are uniformly dissolved, mixed together, and filtered to obtain the product.

[0040] (Comparative formulation example 1) Conventional lotion In Formulation Example 1, the hot water extract of Melilot (Production Example 1B) was replaced with a hot water extract of Melilot (Production Example P) to create a conventional lotion.

[0041] (Prescription example 2) Cream Formula Content (%) 1. 50% ethanol extract of Melilot (Production Example 2B) 1.0 2. Squalane 5.5 3. Olive oil 3.0 4. Stearic acid 2.0 5. Beeswax 2.0 6. Octyldodecyl myristate 3.5 7. Polyoxyethylene cetyl ether (20 E.O.) 3.0 8. Behenyl alcohol 1.5 9. Glyceryl monostearate 2.5 10.Fragrance 0.1 11. Methyl parahydroxybenzoate 0.2 12.1,3-Butylene glycol 8.5 13. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Heat and dissolve components 2-9, mix, and maintain at 70°C to form the oil phase. Heat and dissolve components 1 and 11-13, mix, and maintain at 75°C to form the aqueous phase. Add the aqueous phase to the oil phase and emulsify, then cool while stirring. Add component 10 at 45°C, and further cool to 30°C to obtain the final product.

[0042] (Comparative formulation example 2) Conventional cream In Formulation Example 2, the conventional cream was created by replacing the 50% ethanol extract of sweet clover (Manufacturing Example 2B) with the 50% ethanol extract of sweet clover (Manufacturing Example Q).

[0043] (Prescription example 3) Emulsion Formula Content (%) 1. Ethanol extract of Melilot (Production Example 3C) 0.01 2. Squalane 5.0 3. Olive oil 5.0 4. Jojoba oil 5.0 5. Cetanol 1.5 6. Glyceryl monostearate 2.0 7. Polyoxyethylene cetyl ether (20 E.O.) 3.0 8. Polyoxyethylene sorbitan monooleate (20E.O.) 2.0 9.Fragrance 0.1 10. Propylene glycol 1.0 11. Glycerin 2.0 12. Methyl parahydroxybenzoate 0.2 13. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Heat and dissolve components 1-8, mix, and maintain at 70°C to form the oil phase. Heat and dissolve components 10-13, mix, and maintain at 75°C to form the aqueous phase. Add the aqueous phase to the oil phase and emulsify, then cool while stirring. At 45°C, add component 9, and further cool to 30°C to obtain the final product.

[0044] (Prescription example 4) Gel Formula Content (%) 1. 1,3-butylene glycol extract of Melilot (Production Example 4A) 1.0 2. Ethanol extract of Melilot (Production Example 3B) 1.0 3. Ethanol 5.0 4. Methyl parahydroxybenzoate 0.1 5. Polyoxyethylene hydrogenated castor oil (60 E.O.) 0.1 6.Fragrance (appropriate amount) 7.1,3-Butylene glycol 5.0 8. Glycerin 5.0 9. Xanthan gum 0.1 10. Carboxyvinyl polymer 0.2 11. Potassium hydroxide 0.2 12. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Dissolve components 3-6 and components 1, 2, and 7-12 uniformly, then mix them together to obtain the product.

[0045] (Prescription example 5) Pack Formula Content (%) 1. Hot water extract of Melilot (Preparation Example 1C) 1.0 2. 1,3-butylene glycol extract of Melilot (Production Example 4B) 3.0 3. Polyvinyl alcohol 12.0 4. Ethanol 5.0 5.1,3-Butylene glycol 8.0 6. Methyl parahydroxybenzoate 0.2 7. Polyoxyethylene hydrogenated castor oil (20 E.O.) 0.5 8. Citric acid 0.1 9. Sodium citrate 0.3 10.Fragrance (appropriate amount) 11. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Dissolve ingredients 1-11 uniformly to form the product.

[0046] (Prescription example 6) Foundation Formula Content (%) 1. 50% ethanol extract of Melilot (Production Example 2C) 1.0 2. Stearic acid 2.4 3. Polyoxyethylene sorbitan monostearate (20 E.O.) 1.0 4. Polyoxyethylene cetyl ether (20 E.O.) 2.0 5. Cetanol 1.0 6. Liquid lanolin 2.0 7. Liquid paraffin 3.0 8. Isopropyl myristate 6.5 9. Sodium carboxymethylcellulose 0.1 10. Bentonite 0.5 11. Propylene glycol 4.0 12. Triethanolamine 1.1 13. Methyl parahydroxybenzoate 0.2 14. Titanium dioxide 8.0 15. Talc 4.0 16. Bengara 1.0 17. Yellow iron oxide 2.0 18.Fragrance (appropriate amount) 19. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Heat and dissolve components 2-8, maintain at 80°C to form the oil phase. Swell component 9 thoroughly in component 19, then add components 1 and 10-13 and mix uniformly. Add components 14-17, which have been crushed and mixed in a pulverizer, and stir with a homomixer, maintaining at 75°C to form the aqueous phase. Add the aqueous phase to the oil phase while stirring and emulsify. Then, cool, add component 18 at 45°C, and cool to 30°C while stirring to obtain the product.

[0047] (Prescription example 7) Bath additive Formula Content (%) 1. Ethanol extract of Melilot (Production Example 3A) 0.5 2. 50% ethanol extract of Melilot (Production Example 2A) 0.5 3. Sodium bicarbonate 50.0 4. Yellow No. 202 (1) appropriate amount 5.Fragrance (appropriate amount) 6. Dilute the total volume with sodium sulfate to 100. [Manufacturing Method] Mix ingredients 1-6 uniformly to form the product.

[0048] (Prescription example 8) Ointment Formula Content (%) 1. Hot water extract of Melilot (Production Example 1A) 3.0 2. 1,3-butylene glycol extract of Melilot (Preparation Example 4C) 1.0 3. Polyoxyethylene cetyl ether (30 E.O.) 2.0 4. Glyceryl monostearate 10.0 5. Liquid paraffin 5.0 6. Cetanol 6.0 7. Methyl parahydroxybenzoate 0.1 8. Propylene glycol 10.0 9. Dilute with purified water to make a total volume of 100. [Manufacturing Method] Heat and dissolve components 3-6, mix, and maintain at 70°C to form the oil phase. Heat and dissolve components 1, 2 and 7-9, mix, and maintain at 75°C to form the aqueous phase. Add the aqueous phase to the oil phase and emulsify, then cool to 30°C while stirring to obtain the final product.

[0049] Next, to explain the effects of the present invention in detail, experimental examples will be given. [Examples]

[0050] Experimental Example 1: Examination of the effect on the growth of commensal skin bacteria. Staphylococcus epidermidis (NBRC 12993) and Propionibacterium acnes (JCM 6425) were used as test organisms. Malassezia restricta (NBRC 103918) and Malassezia sympodialis (CBS 7222) were also used as test organisms, and the antibacterial activity of the melilot extract against these test organisms was investigated. Specifically, Staphylococcus epidermidis, Propionibacterium acnes, Malassezia restricta, and Malassezia sympodialis were cultured in a medium containing 1 mg / mL of melilot extract from production examples 1A-4C, or, for comparison, from production examples P-S, and their growth was examined. For the culture medium, Tryptone Sawyer Broth (Kanto Chemical) was used for Staphylococcus epidermidis and Propionibacterium acnes, while Leeming & Notman agar medium (J Clin Microbiol, Vol.25, pp.2017-2019, 1987) was used for Malassezia restricta and Malassezia sympodialis. Staphylococcus epidermidis and Propionibacterium acnes were cultured at 35°C for 24 hours, and turbidity was measured at a wavelength of 600 nm. The bacterial cells of Malassezia sympodialis were cultured at 32.5°C for 24 hours, and Malassezia restricta for 120 hours. The bacterial cells were then suspended in purified water, and the turbidity was measured at a wavelength of 600 nm to investigate the effect of the melilot extracts from production examples 1A-4C or production examples P-S on their growth.

[0051] The control group was defined as the sample without melilot extract, with the turbidity value set to 100%. The survival rate after adding each melilot extract was then determined. As a result, the melilot extract of the present invention showed superior antibacterial activity against Propionibacterium acnes and Malassezia restrictor, while maintaining the bacterial counts of Staphylococcus epidermidis and Malassezia sympodialis, compared to melilot extracts cultivated in sunlight (production examples P-S). Table 3 shows the experimental results for the melilot extract of production example 1B, which showed particularly high efficacy. From this, it became clear that the selective antibacterial activity of the melilot extract is enhanced by the cultivation method using artificial light with a specific wavelength range according to the present invention. Similar effects were observed with melilot extracts using other extraction solvents.

[0052] [Table 3]

[0053] Experimental Example 2: Usage Test A one-month usage trial was conducted on five individuals suffering from acne, using the lotion from Formula Example 1 and the comparison lotion from Formula Example 1. Each participant applied the lotion from Formula Example 1 and the comparison lotion from Formula Example 1 to the left and right halves of their face once daily. A questionnaire was administered after each application to assess the degree of acne prevention and improvement.

[0054] As a result, the lotion containing the melilot extract of the present invention reduced acne problems. Furthermore, no skin problems occurred in any participant during the testing period, and there were no safety concerns. There were also no issues with the degradation of the formulation ingredients.

[0055] Furthermore, the cream of Formulation Example 2 and the cream of Comparative Formulation Example 2 were used in a similar usage test. As a result, the cream containing the melilot extract of the present invention reduced acne problems. Moreover, no skin problems occurred in any participant during the test period, and there were no safety issues. There were also no problems with the degradation of the formulation ingredients. [Industrial applicability]

[0056] Based on the above, the melilot extract of the present invention possesses excellent selective antibacterial properties, capable of suppressing harmful bacteria while preserving beneficial bacteria for the skin, and also exhibits excellent stability. Therefore, the melilot extract of the present invention is expected to have applications in health-related materials, cosmetics, quasi-drugs, and pharmaceuticals.

Claims

1. An antibacterial agent for suppressing acne bacteria while maintaining the number of Staphylococcus epidermidis bacteria, containing an extract of melilotus cultivated under light irradiation with a photosynthetic photon flux density (PPFD) ratio of 4:1 to 2:1 between wavelengths of 570-730 nm and 400-515 nm, using one or more solvents selected from water, lower alcohols, and liquid polyhydric alcohols.

2. An antibacterial agent for suppressing acne bacteria while maintaining the number of Staphylococcus epidermidis bacteria, containing an extract of melilot grown under light irradiation with a photosynthetic photon flux density (PPFD) ratio of 8:1 to 1:1 between wavelengths of 570-730 nm and 400-515 nm, using one or more solvents selected from water, lower alcohols, and liquid polyhydric alcohols.

3. An antibacterial agent for suppressing Malassezia restrictor while maintaining the number of Malassezia sympodialis, containing an extract of melilot cultivated under light with a photosynthetic photon flux density (PPFD) ratio of 4:1 to 2:1 between wavelengths of 570-730 nm and 400-515 nm, prepared with one or more solvents selected from water, lower alcohols, and liquid polyhydric alcohols.

4. An antibacterial agent for suppressing Malassezia restrictor while maintaining the number of Malassezia sympodialis, containing an extract of melilot cultivated under light with a photosynthetic photon flux density (PPFD) ratio of 8:1 to 1:1 between wavelengths of 570-730 nm and 400-515 nm, using one or more solvents selected from water, lower alcohols, and liquid polyhydric alcohols.

5. An acne inhibitor characterized by containing the antibacterial agent described in any one of claims 1 to 4.

6. A seborrheic dermatitis inhibitor characterized by containing the antibacterial agent described in any one of claims 1 to 4.

7. An atopic dermatitis inhibitor characterized by containing the antibacterial agent described in any one of claims 1 to 4.

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