18-methyl Eicosanoic Acid
(Synonyms: 18-甲基二十(烷)酸) 目录号 : GC40619
Additive to hair cosmetics
Cas No.:36332-93-1
Sample solution is provided at 25 µL, 10mM.
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Quality Control & SDS
- View current batch:
- Purity: >95.00%
- COA (Certificate Of Analysis)
- SDS (Safety Data Sheet)
- Datasheet
18-methyl Eicosanoic acid is a main component of the outer layer of the epicuticle of human hair and endows hydrophobicity to the outer hair surface. It is used as an additive to hair cosmetics due to its desirable conditioning effects.
| Cas No. | 36332-93-1 | SDF | |
| 别名 | 18-甲基二十(烷)酸 | ||
| Canonical SMILES | CCC(C)CCCCCCCCCCCCCCCCC(O)=O | ||
| 分子式 | C21H42O2 | 分子量 | 326.6 |
| 溶解度 | DMF: 50 mg/ml,DMSO: 30 mg/ml,Ethanol: 10 mg/ml | 储存条件 | Store at -20°C |
| General tips | 请根据产品在不同溶剂中的溶解度选择合适的溶剂配制储备液；一旦配成溶液，请分装保存，避免反复冻融造成的产品失效。 储备液的保存方式和期限：-80°C 储存时，请在 6 个月内使用，-20°C 储存时，请在 1 个月内使用。 为了提高溶解度，请将管子加热至37℃，然后在超声波浴中震荡一段时间。 |
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| Shipping Condition | 评估样品解决方案：配备蓝冰进行发货。所有其他可用尺寸：配备RT，或根据请求配备蓝冰。 | ||
| 制备储备液 | |||
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1 mg | 5 mg | 10 mg |
| 1 mM | 3.0618 mL | 15.3092 mL | 30.6185 mL |
| 5 mM | 0.6124 mL | 3.0618 mL | 6.1237 mL |
| 10 mM | 0.3062 mL | 1.5309 mL | 3.0618 mL |
| 第一步：请输入基本实验信息（考虑到实验过程中的损耗，建议多配一只动物的药量） | ||||||||||
| 给药剂量 | mg/kg |  |
动物平均体重 | g | |
每只动物给药体积 | ul | |
动物数量 | 只 |
| 第二步：请输入动物体内配方组成（配方适用于不溶于水的药物；不同批次药物配方比例不同，请联系GLPBIO为您提供正确的澄清溶液配方） | ||||||||||
| % DMSO % % Tween 80 % saline | ||||||||||
| 计算重置 | ||||||||||
计算结果:
工作液浓度： mg/ml；
DMSO母液配制方法： mg 药物溶于 μL DMSO溶液（母液浓度 mg/mL，
体内配方配制方法：取 μL DMSO母液，加入 μL PEG300，混匀澄清后加入μL Tween 80，混匀澄清后加入 μL saline，混匀澄清。
1. 首先保证母液是澄清的；
2.
一定要按照顺序依次将溶剂加入，进行下一步操作之前必须保证上一步操作得到的是澄清的溶液，可采用涡旋、超声或水浴加热等物理方法助溶。
3. 以上所有助溶剂都可在 GlpBio 网站选购。
Deletion of the Sox21 gene drastically affects hair lipids
Exp Dermatol 2012 Dec;21(12):974-6.PMID:23171466DOI:10.1111/exd.12050.
The effects of Sox21 gene deletion on hair lipids have been studied. For the cuticle-specific bound lipid 18-methyl Eicosanoic Acid (18-MEA), which was found to predominantly exist as the free form in Sox21(-/-) hair, total levels and distribution were unexpectedly unchanged. This indicates that while the biosynthesis of 18-MEA is unaffected, its covalent attachment to the cuticle surface is disrupted by loss of keratin-associated protein binding partners. Although the class compositions differed, the total ceramide (CER) levels were found to be comparable between Sox21(+/+) and Sox21(-/-) hairs. Deletion of the gene was also found to increase cholesterol sulphate (CS) levels. The biosynthesis process might be associated with cuticle keratinocyte maturation, because both CS and CERs are known bioactives in keratinocyte differentiation.
Chronological ageing of human hair keratin fibres
Int J Cosmet Sci 2010 Dec;32(6):422-34.PMID:20384898DOI:10.1111/j.1468-2494.2009.00570.x.
Examination of very long hair (length > 2.4 m) using a large range of evaluation methods including physical, chemical, biochemical and microscopic techniques has enabled to attain a detailed understanding of natural ageing of human hair keratin fibres. Scrutinizing hair that has undergone little or no oxidative aggression--because of the absence of action of chemical agents such as bleaching or dyeing--from the root to the tip shows the deterioration process, which gradually takes place from the outside to the inside of the hair shaft: first, a progressive abrasion of the cuticle, whilst the cortex structure remains unaltered, is evidenced along a length of roughly 1 m onwards together with constant shine, hydrophobicity and friction characteristics. Further along the fibre, a significant damage to cuticle scales occurs, which correlates well with ceramides and 18-methyl Eicosanoic Acid (18-MEA) decline, and progressive decrease in keratin-associated protein content. Most physical descriptors of mechanical and optical properties decay significantly. This detailed description of natural ageing of human hair fibres by a fine analysis of hair components and physical parameters in relationship with cosmetic characteristics provides a time-dependent 'damage scale' of human hair, which may help in designing new targeted hair care formulations.
Prevention of hair surface aging
J Cosmet Sci 2011 Mar-Apr;62(2):237-49.PMID:21635851doi
The hydrophobic character of the surface of human hair is particularly attributed to the lipid components of the epicuticle and to a layer of covalently bound fatty acids. This outer f-layer mainly consists of 18-methyl Eicosanoic Acid (18-MEA), which is covalently bound to the underlying protein matrix, forming the epicuticle as composite surface structure. Daily weathering and chemical treatments, specifically oxidative bleaching, decrease the hydrophobicity of the outer hair surface drastically.Multiple daily stress, simulated by an automatic test device including shampooing, blow drying and sun light exposure, changed the lipid composition of hair significantly. A marked loss of 18-MEA was observed. Decreasing contact angles are the direct consequence. A new method to determine the "pseudo-static" contact angle on hair was developed. The results correlate with the corresponding data obtained by dynamic contact angle measurements according to Wilhelmy. Besides that, the resorption time of water droplets by the hair surface provides additional information about the intactness of the outer f-layer.Specific proteolipids, which are lipid-modified keratins, are able to reconstruct the surface layer of damaged hair by creating renewed surface hydrophobicity and extending the water resorption time by the hair surface.
Self-assembly of long chain fatty acids: effect of a methyl branch
Phys Chem Chem Phys 2014 Sep 7;16(33):17869-82.PMID:25045762DOI:10.1039/c4cp00512k.
The morphology and molecular conformation of Langmuir-Blodgett deposited and floating monolayers of a selection of straight chain (eicosanoic acid, EA), iso (19-methyl eicosanoic acid, 19-MEA), and anteiso (18-methyl Eicosanoic Acid, 18-MEA) fatty acids have been investigated by Vibrational Sum Frequency Spectroscopy (VSFS), AFM imaging, and the Langmuir trough. While the straight chain fatty acid forms smooth, featureless monolayers, all the branched chain fatty acids display 10-50 nm sized domains (larger for 19-MEA than the 18-MEA) with a homogeneous size distribution. A model is suggested to explain the domain formation and size in terms of the branched fatty acid packing properties and the formation of hemispherical caps at the liquid-air interface. No difference between the chiral (S) form and the racemic mixture of the 18-MEA is observed with any of the utilized techniques. The aliphatic chains of the straight chain fatty acids appear to be oriented perpendicular to the sample surface, based on an orientational analysis of VSFS data and the odd/even effect. In addition, the selection of the subphase (neat water or CdCl2 containing water buffered to pH 6.0) used for the LB-deposition has a profound influence on the monolayer morphology, packing density, compressibility, and conformational order. Finally, the orientation of the 19-MEA dimethyl moiety is estimated, and a strategy for performing an orientational analysis to determine the complete molecular orientation of the aliphatic chains of 19-MEA and 18-MEA is outlined and discussed.
A systematic method for the sensitive and specific determination of hair lipids in combination with chromatography
J Chromatogr B Analyt Technol Biomed Life Sci 2005 Sep 5;823(2):131-42.PMID:16006202DOI:10.1016/j.jchromb.2005.06.014.
A systematic method for the sensitive, precise and accurate determination of hair lipids, including trace amounts of intrinsic endogenous cholesterol (CH), ceramide/N-palmitoyl-DL-dihydrosphingosine (CER/PDS), cholesterol sulfate (CS) and chemically bound 18-methyl Eicosanoic Acid (18-MEA), has been developed in combination with TLC/FID (flame ionization detection), LC/MS and GC/MS. TLC/FID was used for the simultaneous determination of squalene (SQ), wax esters (WEs), triglycerides (TGs) and free fatty acids (FFAs). Optimal conditions for LC/MS to determine CS and 18-MEA were developed using selected ion monitoring (SIM) under the negative ion mode of electrospray ionization. An alternative procedure for the determination of 18-MEA was also established using commercially available heneicosanoic acid (HEA). In GC/MS, the optimal selection of ions for SIM of trimethylsilylated CH and CER/PDS, and the use of on-column injection has enabled their simultaneous detection. This newly developed method has been used to characterize the hair lipid composition from the proximal root end to the distal tip of chemically untreated hair fibers from two different females, and specific changes of hair lipids probably due to its origin and individuals have been demonstrated for the first time. This method may be useful for clarifying the important roles of intrinsic endogenous 18-MEA, CS, CH and CERs in the function of the cell membrane complex of hair fibers.