Fatty acid composition containing palmitoleic acid

Abstract

To provide a fatty acid composition containing palmitoleic acid having antibacterial action in a high content and having excellent preservation stability.SOLUTION: A fatty acid composition contains (A) a fatty acid having 16 carbon atoms and a cis double bond at the 9-position, and (B) a fatty acid having 16 carbon atoms and a trans double bond at the 9-position, wherein the content ratio of the component (A) to the component (B) [(A): (B)] is 99.99:0.01 to 60:40 by mass ratio.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fatty acid composition containing palmitoleic acid. More specifically, the present invention relates to a fatty acid composition containing a high content of palmitoleic acid, which has an antibacterial effect against Staphylococcus aureus, and which can contribute to improving safety and storage stability in the fields of cosmetics, foods, pharmaceuticals, etc. [Background technology]

[0002] Traditionally, preservatives and alcohols such as ethanol have been commonly used in cosmetics, pharmaceuticals, industrial products, and other products to prevent microbial contamination. While these ingredients are certainly effective, they pose problems such as skin irritation and environmental impact. Furthermore, the use of antibiotics for infectious diseases poses several issues to consider, such as the emergence of resistant bacteria. In particular, for cosmetics and topical skin preparations for sensitive skin, antibacterial ingredients can irritate the skin, so there is a demand for naturally derived antibacterial ingredients with low irritation. For example, in recent years, it has been reported that Staphylococcus aureus is involved in the worsening of symptoms at the lesion site on the skin of patients with atopic dermatitis, and it has been discovered that palmitoleic acid has selective antibacterial activity against Staphylococcus aureus. As a selective antibacterial agent against Staphylococcus aureus, a fatty acid composition containing 55 mol% or more of palmitoleic acid and having a palmitoleic acid to oleic acid content ratio of 2.4 or more in terms of molar ratio, and a method for producing the same have been proposed (Patent Document 1).

[0003] Patent Document 1 describes a method for producing a fatty acid composition containing a high content of palmitoleic acid by using a transformed strain of Saccharomyces cerevisiae, which has high lipid production capacity, to produce an oil containing triglycerides having palmitoleic acid at the sn-1 and sn-3 positions, and using a lipase that preferentially liberates fatty acids at the sn-1 and sn-3 positions of the triglycerides from the oil. However, the technology described in Patent Document 1 requires the use of a transformant of Saccharomyces cerevisiae to produce the raw oils and fats in the process of producing a fatty acid composition, and also requires the use of a special lipase derived from a microorganism belonging to the genus Pseudozyma or a microorganism belonging to the genus Alcaligenes. Therefore, there are concerns that there are high hurdles to market entry from the perspective of the Food Sanitation Act, etc.

[0004] Furthermore, conventional antibacterial ingredients containing unsaturated fatty acids such as palmitoleic acid have the problem of making it difficult to maintain the quality of the product due to deterioration and alteration caused by oxidation. To address this problem, synthetic antioxidants or food-grade antioxidants, such as dibutylhydroxytoluene (BHT) and butylhydroxyanisole (BHA), are sometimes used. However, the effectiveness of these synthetic antioxidants tends to decrease due to heating during processing. Tocopherol, the most widely used antioxidant in food, is excellent in terms of safety and physical properties, but its antioxidant activity against lipids containing polyunsaturated fatty acids is poor. Although methods of adding synthetic antioxidants to tocopherol have been proposed, this method poses the problem of reducing the purity of the natural ingredients. To address this issue, an oxidation inhibitor for oils and fats has been proposed, which contains as an active ingredient an aminocarbonyl compound having a structure in which the amino group of a compound having a sphingoid base structure is bonded to the carbonyl group of a carbonyl compound (Patent Document 2). However, the oxidation inhibitor described in Patent Document 2 contains an aminocarbonyl compound having a sphingoid base structure in its structure, which raises concerns about its influence on the properties of antibacterial compositions containing fatty acids. Furthermore, the oxidation inhibitor described in Patent Document 2 does not simultaneously satisfy both antibacterial activity and storage stability, and its effectiveness is limited.

[0005] Therefore, there is a demand for a fatty acid composition that contains a high content of palmitoleic acid, can be obtained without using genetic engineering technology or special lipases, has good storage stability by suppressing denaturation and deterioration of the fatty acid composition due to oxidation, etc., and can be easily used in foods and cosmetics. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-140940 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-175983 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the present invention aims to provide a fatty acid composition that contains a high content of palmitoleic acid, which has antibacterial properties, and has excellent storage stability without the use of synthetic antioxidants, etc., and that can be obtained without the use of genetic engineering technology or special lipases, and that can be easily applied to food and cosmetic applications. [Means for solving the problem]

[0008] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a fatty acid composition containing (A) a fatty acid having 16 carbon atoms and a cis double bond at position 9, and (B) a fatty acid having 16 carbon atoms and a trans double bond at position 9, wherein the content ratio of component (A) to component (B) [(A):(B)] is 99.99:0.01 to 60:40 by mass, has excellent antibacterial activity and storage stability. Further research led to the completion of the present invention.

[0009] That is, the present invention relates to the following: [1] A fatty acid composition comprising (A) a fatty acid having 16 carbon atoms and a cis double bond at position 9, and (B) a fatty acid having 16 carbon atoms and a trans double bond at position 9, wherein the content ratio of component (A) to component (B) [(A):(B)] is 99.99:0.01 to 60:40 by mass. [2] The fatty acid composition according to [1], containing component (A) and component (B) in a total amount of 60% by mass or more based on the total amount of the fatty acid composition. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a fatty acid composition that exhibits excellent antibacterial activity against Staphylococcus aureus and has excellent storage stability. The fatty acid composition provided by the present invention can be obtained without using genetic engineering techniques or special lipases, and can maintain good storage stability without using synthetic antioxidants, etc., so it is safe and has little impact on the environment, and can be easily applied to foods and cosmetics. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention provides a fatty acid composition containing a high content of palmitoleic acid (hereinafter also referred to as "the fatty acid composition of the present invention" in this specification). The fatty acid composition of the present invention contains (A) a fatty acid having 16 carbon atoms and a cis double bond at the 9th position, and (B) a fatty acid having 16 carbon atoms and a trans double bond at the 9th position, in the following content ratio:

[0012] In the fatty acid composition of the present invention, the fatty acid having 16 carbon atoms and a cis double bond at the 9-position contained as component (A) includes (Z)-9-hexadecenoic acid (palmitoleic acid). In addition, in the fatty acid composition of the present invention, examples of fatty acids having 16 carbon atoms and a trans double bond at the 9th position contained as component (B) include (E)-9-hexadecenoic acid (palmitoeladic acid, trans-palmitoleic acid).

[0013] The content ratio of component (A) to component (B) in the fatty acid composition of the present invention [(A):(B)] is 99.99:0.01 to 60:40 in mass ratio. From the viewpoint of antibacterial activity against Staphylococcus aureus, the content ratio of component (A) to component (B) [(A):(B)] is preferably 99.99:0.01 to 80:20 by mass, more preferably 99.99:0.01 to 95:5, and particularly preferably 99.99:0.01 to 99.5:0.5.

[0014] From the viewpoint of antibacterial activity against Staphylococcus aureus and storage stability, the total content of component (A) and component (B) in the fatty acid composition of the present invention is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount of the fatty acid composition of the present invention.

[0015] From the viewpoint of antibacterial activity, the fatty acid composition of the present invention preferably further contains (C) a polyunsaturated fatty acid. In the fatty acid composition of the present invention, polyunsaturated fatty acids that can be preferably contained as component (C) include polyunsaturated fatty acids having 16 to 22 carbon atoms. Examples of such polyunsaturated fatty acids include linoleic acid ((9Z,12Z)-9,12-octadecadienoic acid (C18:2)), α-linolenic acid ((9Z,12Z,15Z)-9,12,15-octadecanetrienoic acid (C18:3)), γ-linolenic acid ((6Z,9Z,12Z)-6,9,12-octadecatrienoic acid (C18:3)), stearidonic acid ((6Z,9Z,12Z,15Z)-6,9,12,15-octadecanetrienoic acid (C18:3)), and α-linolenic acid ((6Z,9Z,12Z)-6,9,12-octadecatrienoic acid (C18:3)). Catetraenoic acid (C18:4), (11Z,14Z)-11,14-icosadienoic acid (C20:2), mead acid ((5Z,8Z,11Z)-5,8,11-icosatrienoic acid ((C20:3)), γ-homolinolenic acid ((8Z,11Z,14Z)-8,11,14-icosatrienoic acid (C20:3)), arachidonic acid ((5Z,8Z,11Z,14Z)-5,8,11,14-icosatetraenoic acid ((C20:4)) ), timnodonic acid ((5Z,8Z,11Z,14Z,17Z)-5,8,11,14,17-icosapentaenoic acid ((C20:5)), (4Z,9E,15E,19Z)-4,9,15,19-docosatetraenoic acid ((C22:4)), (4Z,7Z,10Z,13Z,16Z)-4,7,10,13,16-docosapentaenoic acid ((C22:5), (7Z,10Z,13Z,16Z,19Z)-7,10,13,1 Examples include 6,19-docosapentaenoic acid (C22:5), clupanodonic acid (sardine acid) (4,8,12,15,19-docosapentaenoic acid (C22:5)), and docosahexaenoic acid ((4Z,7Z,10Z,13Z,16Z,19Z)-4,7,10,13,16,19-docosahexaenoic acid (C22:6)). One of these polyunsaturated fatty acids may be selected and used alone, or two or more may be selected and used in combination.

[0016] From the viewpoint of the oxidation stability of the fatty acid composition of the present invention, the content of component (C) in the fatty acid composition of the present invention is preferably 30 mass% or less, and more preferably 15 mass% or less, relative to the total amount of the fatty acid composition. On the other hand, from the viewpoint of the antibacterial activity and storage stability of the fatty acid composition of the present invention, component (C) is preferably contained in an amount of 0.01 mass% to 0.1 mass%, and more preferably 0.01 mass% to 0.05 mass%, relative to the total amount of the fatty acid composition of the present invention.

[0017] The fatty acid composition of the present invention may further contain saturated fatty acids within the range that does not impair the characteristics of the present invention. Examples of saturated fatty acids that can be contained in the fatty acid composition of the present invention include saturated fatty acids having 8 to 22 carbon atoms, such as octanoic acid (caprylic acid), 2-ethylhexanoic acid, decanoic acid (capric acid), dodecanoic acid (lauric acid), tetradecanoic acid (myristic acid), pentadecanoic acid (pentadecylic acid), hexadecanoic acid (palmitic acid), heptadecanoic acid (margaric acid), octadecanoic acid (stearic acid), isostearic acid (16-methylheptadecanoic acid), eicosanoic acid (arachidic acid), and docosanoic acid (behenic acid).

[0018] The fatty acid composition of the present invention may further contain general oil-soluble additives within the range that does not impair the effects of the present invention. The general oil-soluble additives can be used in amounts according to their intended use.

[0019] The fatty acid composition of the present invention can be prepared by mixing and stirring components (A) and (B) together, if necessary, with component (C), saturated fatty acids, and general oil-soluble additives, preferably under a nitrogen atmosphere, until homogeneous.

[0020] The fatty acid composition of the present invention contains a high content of palmitoleic acid, which has excellent antibacterial activity against Staphylococcus aureus, and exhibits excellent antibacterial activity against Staphylococcus aureus as well as excellent storage stability. Here, in this specification, "storage stability" means that the degree of unsaturation of the fatty acid composition does not decrease and the composition does not undergo denaturation or deterioration due to oxidation or the like. The fatty acid composition of the present invention can be prepared without using genetic engineering techniques or special lipases, and therefore has little impact on safety and the environment, and can be easily applied to foods and cosmetics.

[0021] The content of each fatty acid contained in the fatty acid composition of the present invention can be determined by carrying out fatty acid composition analysis by gas chromatography. Examples of analytical conditions for fatty acid composition analysis are shown below. <Fatty acid purity analysis (fatty acid composition analysis)> Equipment: Gas chromatograph ("Nexis GC-2030", Shimadzu Corporation) Detector: Flame ionization detector (FID) Carrier gas: Nitrogen Column: Capillary column ("TC-70", 60 m x 0.25 mm x 0.25 mm, GL Sciences Inc.) Temperature condition: 180℃ (120min Hold) Pretreatment: Methyl esterification (fatty acid methylation kit, GL Sciences Inc.)

[0022] The fatty acid composition of the present invention can be used as a pharmaceutical or cosmetic composition by adding it to an oily base to form an oily composition, or by adding it to an oily component to form a water-in-oil emulsion composition or an oily gel, or by adding it to edible oils and fats to form a food composition. [Example]

[0023] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. [Example]

[0024] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 0.333 g of palmitelaidic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, and the mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40°C until homogenous. Then, 3.00 g of linoleic acid ("EXTRA LINOLEIC 99" from NOF Corporation) was added, and the mixture was stirred for an additional 10 minutes to obtain the fatty acid composition of Example 1. [Example]

[0025] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 4.91 g of palmitelaidic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, and the mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40°C until homogenous. Then, 1.45 g of linolenic acid ("α-Linolenic Acid" from Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was stirred for another 10 minutes to obtain the fatty acid composition of Example 2. [Example]

[0026] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 1.95 g of palmitelaidic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer. The mixture was heated to 40°C in a water bath while stirring under a nitrogen atmosphere until homogenous. 7.01 g of linolenic acid ("α-Linolenic Acid" from Fujifilm Wako Pure Chemical Industries, Ltd.) was then added, and the mixture was stirred for an additional 10 minutes to obtain the fatty acid composition of Example 3. [Example]

[0027] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 0.72 g of palmitoleic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, and the mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40°C until homogenous. Then, 17.28 g of linoleic acid ("EXTRA LINOLEIC 99" from NOF Corporation) was added, and the mixture was stirred for another 10 minutes to obtain the fatty acid composition of Example 4. [Example]

[0028] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 16.90 g of palmitoleic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, and the mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40°C until homogenous. Then, 0.047 g of linoleic acid ("EXTRA LINOLEIC 99" from NOF Corporation) was added, and the mixture was stirred for an additional 10 minutes to obtain the fatty acid composition of Example 5. [Example]

[0029] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 0.009 g of palmitoleic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, and the mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40°C until homogenous. Then, 0.015 g of linoleic acid (EXTRA LINOLEIC 99 from NOF Corporation) was added, and the mixture was stirred for an additional 10 minutes to obtain the fatty acid composition of Example 6. [Example]

[0030] 30 g of palmitoleic acid ("Palmitoleic acid" from Thermo Scientific Chemicals) and 0.009 g of palmitelaidic acid ("trans-Palmitoleic acid" from Target Mol) were added to a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, and the mixture was stirred for 10 minutes in a nitrogen atmosphere while being heated to 40°C in a water bath, to obtain the fatty acid composition of Example 7. Comparative Example 1

[0031] Palmitoleic acid ("Palmitoleic acid," Thermo Scientific Chemicals) was the fatty acid for Comparative Example 1. Comparative Example 2

[0032] Palmitoleic acid ("trans-Palmitoleic acid", TargetMol) was used as the fatty acid in Comparative Example 2.

[0033] The content of each fatty acid in each of the fatty acid compositions of Examples 1 to 7 and each of the fatty acids in Comparative Examples 1 and 2 is shown in Table 1.

[0034] [Table 1]

[0035] The antibacterial activity against Staphylococcus aureus and storage stability of each of the fatty acid compositions of Examples 1 to 7 and each of the fatty acids of Comparative Examples 1 and 2 were evaluated as follows. The evaluation results are shown in Table 2.

[0036] (1) Evaluation of antibacterial activity against Staphylococcus aureus In order to evaluate the antibacterial activity of each of the fatty acid compositions of Examples 1 to 7 and each of the fatty acids of Comparative Examples 1 and 2, the minimum inhibitory concentration (MIC) against Staphylococcus aureus was measured by the following procedure. (i) Preparation of test bacterial solution A standard strain of Staphylococcus aureus (ATCC 25923) was cultured in Mueller-Hinton medium, and the resulting colonies were picked up and suspended in sterile physiological saline to a concentration of 0.5 McFarland standard turbidity (approximately 1.5 × 10 8 A bacterial cell solution containing 1000 CFU (Colony Forming Unit) / mL was prepared. (ii) Sample preparation In a 96-well plate, each of the fatty acid compositions of Examples 1 to 7 and each of the fatty acids of Comparative Examples 1 and 2 was dissolved in dimethyl sulfoxide (DMSO) to an initial concentration of approximately 1,000 μg / mL. Next, a two-fold dilution series of each of the fatty acid compositions or fatty acid solutions was prepared in a row of wells, and the solution was serially diluted stepwise to prepare sample solutions (e.g., 1,000 μg / mL, 500 μg / mL, 250 μg / mL, 125 μg / mL, 62.5 μg / mL, 31.25 μg / mL, 15.625 μg / mL, 7.8125 μg / mL, etc.). (iii) Measurement of minimum inhibitory concentration The sample solution prepared above was diluted 10-fold with sterile saline to prepare 5 x 10 cells per well. 4 The cells were inoculated to a concentration of CFU / mL and cultured at 37°C for 18 to 24 hours. The growth of Staphylococcus aureus in each well was observed visually or with a spectrophotometer (turbidity at 600 nm), and the minimum concentration of the sample solution at which no growth of Staphylococcus aureus was observed was taken as the minimum inhibitory concentration (MIC). (iv) Evaluation of antibacterial activity Based on the measured MICs, the antibacterial activity was evaluated according to the following criteria. <Evaluation criteria> ◎ (Excellent antibacterial activity): MIC is 8μg / mL or less ○ (moderate antibacterial activity observed): MIC is greater than 8 μg / mL and less than 64 μg / mL × (weak antibacterial effect): MIC exceeds 64 μg / mL

[0037] (2) Storage stability The storage stability of each of the fatty acid compositions of Examples 1 to 7 and each of the fatty acids of Comparative Examples 1 and 2 was evaluated by measuring the iodine value of each fatty acid composition and each fatty acid in accordance with the standard analysis method for fats and oils, JOCS3.3.3. That is, each fatty acid composition and each fatty acid was stored at 40°C, and the iodine value was measured after each storage period of 1 day (24 hours), 15 days, and 30 days. The iodine value at the start of storage was used as the reference value, and the fluctuation rate of the iodine value was calculated from the measured iodine values ​​after each storage period using the following formula. Fluctuation rate (%) = [(reference value - iodine value at the time of measurement) / reference value] x 100 The storage stability was evaluated according to the following criteria, using the largest rate of change calculated at each measurement point (1 day, 15 days, 30 days) during the storage period as the maximum rate of change. <Evaluation criteria> ◎: Maximum fluctuation rate is 5% or less ○: The maximum fluctuation rate is more than 5% and less than 10% ×: Maximum fluctuation rate exceeds 10%

[0038] [Table 2]

[0039] As shown in Tables 1 and 2, the fatty acid compositions of Examples 1 to 7 contained high amounts of palmitoleic acid (62.5% by mass to 99.97% by mass) and palmitoleaidic acid (0.03% by mass to 36.0% by mass), and were all evaluated to have good antibacterial activity and good storage stability. In particular, the fatty acid composition of Example 6, which contained 99.92% by mass of palmitoleic acid and 0.03% by mass of palmitoleic acid (content ratio of component (A) to component (B) [(A):(B)] = 99.97:0.03 (mass ratio)) and 0.05% by mass of linoleic acid, was evaluated to have excellent antibacterial activity and storage stability. On the other hand, Comparative Example 1, which contained only palmitoleic acid as a constituent component and did not contain palmitoleic acid, was evaluated as having excellent antibacterial activity but poor storage stability, and Comparative Example 2, which contained only palmitoleic acid as a constituent component and did not contain palmitoleic acid, was evaluated as having good storage stability but did not exhibit good antibacterial activity. [Industrial Applicability]

[0040] As described above in detail, the present invention can provide a fatty acid composition that contains a high content of palmitoleic acid, which has excellent antibacterial activity against Staphylococcus aureus, and that exhibits excellent antibacterial activity against Staphylococcus aureus and has excellent storage stability. The fatty acid composition provided by the present invention can be prepared without using genetic engineering techniques or special lipases, and therefore is safe and has little impact on the environment, and can be easily applied to foods and cosmetics.

Claims

1. A fatty acid composition comprising (A) a fatty acid having 16 carbon atoms and having a cis double bond at position 9, and (B) a fatty acid having 16 carbon atoms and having a trans double bond at position 9, wherein the content ratio of component (A) to component (B) [(A):(B)] is 99.99:0.01 to 60:40 by mass.

2. 2. The fatty acid composition according to claim 1, wherein the total amount of component (A) and component (B) is 60% by mass or more based on the total amount of the fatty acid composition.

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