Fatty acid composition containing palmitoleic acid

Abstract

The present invention relates to a fatty acid composition comprising (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 [(A):(B)] of component (A) to component (B) ranges from 99.99:0.01 to 60:40 by mass.　According to the present invention, a fatty acid composition is provided which contains palmitoleic acid in a high content, exhibiting antibacterial activity, and has excellent storage stability.

Description

Fatty acid composition containing palmitoleic acid

[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 the safety and storage stability of cosmetics, foods, pharmaceuticals, etc.

[0002] Conventionally, preservatives and alcohols such as ethanol have been commonly used in various products, including cosmetics, pharmaceuticals, and industrial 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 involves several considerations, such as the emergence of resistant bacteria. In particular, in light of the skin irritation of antibacterial ingredients, naturally derived antibacterial ingredients with low irritation are desired for cosmetics and topical skin preparations for sensitive skin. For example, in recent years, it has been reported that Staphylococcus aureus is involved in the exacerbation of symptoms at the lesion site in patients with atopic dermatitis. Palmitoleic acid has been found to have selective antibacterial activity against Staphylococcus aureus. A fatty acid composition containing 55 mol% or more of palmitoleic acid and having a palmitoleic acid to oleic acid molar ratio of 2.4 or more has been proposed as a selective antibacterial agent against Staphylococcus aureus, as well as a method for producing the same (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-producing ability, 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 production process of the 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 standpoint 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 product quality due to oxidative degradation and alteration. To address this issue, synthetic antioxidants and food-grade antioxidants, such as dibutylhydroxytoluene (BHT) and butylhydroxyanisole (BHA), have sometimes been used. However, these synthetic antioxidants tend to lose their antioxidant activity due to heating during processing. Furthermore, tocopherol, the most widely used food antioxidant, is excellent in terms of safety and physical properties, but its antioxidant activity against lipids containing polyunsaturated fatty acids is poor. Although a method of adding synthetic antioxidants to tocopherol has been proposed, this method suffers from the problem of reducing the purity of natural ingredients. To address this issue, an oxidation inhibitor for oils and fats has been proposed, whose active ingredient is an aminocarbonyl compound, which has 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.

[0006] JP 2018-140940 A JP 2016-175983 A

[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.

[0008] As a result of intensive studies 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 studies have led to the completion of the present invention.

[0009] That is, the present invention relates to the following: [1] A fatty acid composition containing (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] The fatty acid composition according to [1], wherein the total content of component (A) and component (B) is 60% by mass or more based on the total amount of the fatty acid composition.

[0010] The present invention provides 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 recombination technology or special lipases, and can maintain good storage stability without using synthetic antioxidants, etc., so it has little impact on safety and the environment and can be easily applied to foods and cosmetics.

[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"). The fatty acid composition of the present invention contains (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, in the following content ratio:

[0012] In the fatty acid composition of the present invention, an example of a fatty acid having 16 carbon atoms and a cis double bond at position 9 contained as component (A) is (Z)-9-hexadecenoic acid (palmitoleic acid). In addition, in the fatty acid composition of the present invention, an example of a fatty acid having 16 carbon atoms and a trans double bond at position 9 contained as component (B) is (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, in mass ratio, 99.99:0.01 to 60:40. From the viewpoint of antibacterial activity against Staphylococcus aureus, the content ratio of component (A) to component (B) [(A):(B)] is, in mass ratio, preferably 99.99:0.01 to 80:20, 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 mass% or more, more preferably 80 mass% or more, and even more preferably 90 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, examples of 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-octadecatrienoic 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-Octadecatetraenoic 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)-7,10,13,16,19-docosapentaenoic acid (C22:5), clupanodonic acid (sardine acid) (4,8,12,15,19-docosapentaenoic acid (C22:5)), docosahexaenoic acid ((4Z,7Z,10Z,13Z,16Z,19Z)-4,7,10,13,16,19-docosahexaenoic acid (C22:6)), etc. 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 usually 40% by mass or less, preferably 30% by mass or less, and more preferably 15% by 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, the content of component (C) is preferably 0.01% by mass to 0.1% by mass, and more preferably 0.01% by mass to 0.05% by 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, provided that the characteristics of the present invention are not impaired. 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), icosanoic acid (arachidic acid), and docosanoic acid (behenic acid). One of these saturated fatty acids may be selected and used alone, or two or more may be selected and used in combination.

[0018] Furthermore, the fatty acid composition of the present invention may further contain common oil-soluble additives such as an oily base, an emollient, an oil-soluble preservative, an oil-soluble UV absorber, etc., within the range that does not impair the characteristics of the present invention. Common oil-soluble additives can be used in amounts generally used depending on the purpose of use.

[0019] The fatty acid composition of the present invention can be prepared by adding component (C), saturated fatty acids, and general oil-soluble additives to component (A) and component (B) as needed, mixing and stirring the mixture 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. Herein, "storage stability" refers to the absence of a decrease in the degree of unsaturation of the fatty acid composition and the absence of denaturation or deterioration due to oxidation or the like. Note that, in this specification, the "degree of unsaturation of the fatty acid composition" is calculated as the number of hydrogen atoms reduced primarily by the unsaturated bonds of the fatty acids contained in the fatty acid composition. The fatty acid composition of the present invention can be prepared without the use of genetic engineering technology or special lipases, and is therefore safe, has little impact on 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. <Analysis of fatty acid purity (fatty acid composition analysis)> Apparatus: gas chromatograph ("Nexis GC-2030", Shimadzu Corporation) Detector: flame ionization detector (FID) Carrier gas: nitrogen Column: capillary column ("TC-70" (70% cyanopropylpolysilphenylene-siloxane), 60 m x 0.25 mm x 0.25 mm, GL Sciences Inc.) Temperature condition: 180°C (120 min 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.

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

[0024] To a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity = 99%) and 0.333 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity = 99.36%) were added, and the mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40 ° C. until homogenous. Thereafter, 3.00 g of linoleic acid ("EXTRA LINOLEIC 99", NOF Corporation, purity = 99%) was added, and the mixture was stirred for an additional 10 minutes to obtain the fatty acid composition of Example 1.

[0025] A 50 mL four-neck flask equipped with a thermometer, nitrogen inlet tube, and stirrer was charged with 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity = 99%) and 4.91 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity = 99.36%). The mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40 ° C., and homogenized. Subsequently, 1.45 g of linolenic acid ("α-Linolenic Acid from Plants", Fujifilm Wako Pure Chemical Industries, purity = 98%) was added and stirred for a further 10 minutes to obtain the fatty acid composition of Example 2.

[0026] A 50 mL four-neck flask equipped with a thermometer, nitrogen inlet tube, and stirrer was charged with 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity = 99%) and 1.95 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity = 99.36%). The mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40 ° C., and homogenized. Thereafter, 7.01 g of linolenic acid ("α-Linolenic Acid from Plants", Fujifilm Wako Pure Chemical Industries, purity = 98%) was added and stirred for a further 10 minutes to obtain the fatty acid composition of Example 3.

[0027] A 50 mL four-neck flask equipped with a thermometer, nitrogen inlet tube, and stirrer was charged with 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity = 99%) and 0.72 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity = 99.36%). The mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40 ° C., and homogenized. Thereafter, 17.28 g of linoleic acid ("EXTRA LINOLEIC 99", NOF Corporation, purity = 99%) was added, and the mixture was stirred for a further 10 minutes to obtain the fatty acid composition of Example 4.

[0028] In a 50 mL four-neck flask equipped with a thermometer, nitrogen inlet tube, and stirrer, 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity = 99%) and 16.90 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity = 99.36%) were added, and the mixture was stirred in a water bath under a nitrogen atmosphere while heating to 40 ° C. until homogenous. Thereafter, 0.047 g of linoleic acid ("EXTRA LINOLEIC 99", NOF Corporation, purity = 99%) was added, and the mixture was stirred for a further 10 minutes to obtain the fatty acid composition of Example 5.

[0029] A 50 mL four-neck flask equipped with a thermometer, nitrogen inlet tube, and stirrer was charged with 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity = 99%) and 0.009 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity = 99.36%). The mixture was stirred in a water bath under a nitrogen atmosphere while being heated to 40 ° C., and homogenized. Thereafter, 0.015 g of linoleic acid (EXTRA LINOLEIC 99, NOF Corporation, purity = 99%) was added, and the mixture was stirred for a further 10 minutes to obtain the fatty acid composition of Example 6.

[0030] To a 50 mL four-neck flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, 30 g of palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity=99%) and 0.009 g of palmitoleidic acid ("trans-Palmitoleic acid", TargetMol, purity=99.36%) were added, and the mixture was stirred for 10 minutes in a nitrogen atmosphere while being heated to 40°C in a water bath, thereby obtaining the fatty acid composition of Example 7. Comparative Example 1

[0031] Palmitoleic acid ("Palmitoleic acid", Thermo Scientific Chemicals, purity=99%) was used as the fatty acid in Comparative Example 1. Comparative Example 2

[0032] Palmitoleic acid ("trans-Palmitoleic acid", TargetMol, purity=99.36%) was used as the fatty acid of 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]

[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, and the evaluation results are shown in Table 2.

[0036] (1) Evaluation of antibacterial activity against Staphylococcus aureus 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 (Staphylococcus aureus ATCC 25923) was cultured in Mueller-Hinton medium, and the resulting colonies were picked and suspended in sterile physiological saline to obtain a 0.5 McFarland standard turbidity (approximately 1.5 × 10 ８A bacterial cell solution of 1000 μg / mL (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 2-fold dilution series of each solution of the fatty acid composition or fatty acid with DMSO was prepared in a row of wells, and the solution was sequentially diluted stepwise with DMSO to prepare a sample solution (for example, the concentrations of the fatty acid composition and fatty acid in the sample were 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 A bacterial solution of the standard strain of Staphylococcus aureus was diluted 10-fold with sterile physiological saline and added to the sample solution in each well. ４ 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) of the fatty acid composition or fatty acid used in preparing the sample. (iv) Evaluation of antibacterial activity Based on the measured MIC, the antibacterial activity was evaluated according to the following evaluation criteria. <Evaluation criteria> ◎ (Excellent antibacterial activity observed): MIC is 8 μg / mL or less ○ (Moderate antibacterial activity observed): MIC is greater than 8 μg / mL and less than 64 μg / mL × (Weak antibacterial activity): MIC is greater than 64 μg / mL

[0037] (2) Evaluation of Storage Stability The storage stability of each fatty acid composition of Examples 1 to 7 and each fatty acid 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 Method for Analysis of Fats, Oils, and Related Materials (JOCS) 3.3.3. 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 iodine value fluctuation rate was calculated from the iodine value measured after each storage period using the following formula: Fluctuation Rate (%) = [(Reference Value - Iodine Value at Measurement Time) / Reference Value] × 100. The storage stability was evaluated according to the following evaluation criteria, with the largest fluctuation rate among the fluctuation rates calculated at each measurement time point (after 1 day, 15 days, and 30 days) during the storage period being defined as the maximum fluctuation rate. <Evaluation criteria> ◎: The maximum fluctuation rate is 5% or less. ○: The maximum fluctuation rate is more than 5% and 10% or less. ×: The maximum fluctuation rate is more than 10%.

[0038]

[0039] As shown in Tables 1 and 2, the fatty acid compositions of Examples 1 to 7 contained high contents of palmitoleic acid (61.9% to 98.97% by mass) and palmitoleaidic acid (0.03% to 35.8% by mass), and were evaluated to have good antibacterial activity and good storage stability. In particular, the fatty acid composition of Example 6, which contained 98.92% by mass of palmitoleic acid and 0.03% by mass of palmitoleaidic acid (the content ratio of components (A) and (B) [(A):(B)] = 99.97:0.03 (mass ratio)) and 0.05% by mass of linoleic acid, had an MIC of 3.6 μg / mL and a maximum variation rate of 4.0% in iodine value, and was evaluated to have excellent antibacterial activity and storage stability. On the other hand, the fatty acid of Comparative Example 1, which does not contain palmitoleic acid and is composed only of palmitoleic acid, was evaluated to have excellent antibacterial activity but poor storage stability.Furthermore, the fatty acid of Comparative Example 2, which does not contain palmitoleic acid and is composed only of palmitoleic acid, had good storage stability but did not exhibit good antibacterial activity.

[0040] As described above in detail, the present invention provides a fatty acid composition that contains a high content of palmitoleic acid, which has an excellent antibacterial effect 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 recombination technology or special lipases, and therefore has little impact on safety and the environment, and can be easily applied to foods and cosmetics.

[0041] This application is based on patent application No. 2024-112066 filed in Japan, the contents of which are incorporated in their entirety herein.

Claims

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 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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