Addy Jeff, Oliphant Tiffany, Harper Robert
Floratech, Chandler, AZ 85225 (J.A., T.O.), and Harper & Associates, La Jolla, CA 92037 (R.H.).
J Cosmet Sci. 2017 Jan/Feb;68(1):59-67.
Skin surface lipids (SSLs) greatly affect the skin physiology and are thought to be involved in skin processes such as thermoregulation, bacterial colonization, and barrier function and maintenance. SSLs are primarily composed of fatty acids, triglycerides, cholesterol, steryl esters, wax esters, and squalene. The objective of this research was to evaluate and better understand the SSL composition and variation in an age- and sex-controlled population, and create an appropriate botanically derived mimetic.
SSL samples taken from the foreheads of 59 healthy, 22-year-old females were analyzed by gas chromatography mass spectrometry (GC-MS). Using botanically derived raw materials from , , and , a mimetic was engineered via a series of esterification reactions and lipid components quantitated with GC-MS. The glyceride and wax ester components were produced by the interesterification of and under specified conditions. The steryl ester component was produced by the esterification of the fatty acids of and phytosterols under similar conditions.
The following major classes of lipids were found and quantified by percent composition: glycerides, free fatty acids, squalene, wax esters, steryl esters, and cholesterol. The variability between subjects for each component was minimal; however, the greatest variation was seen for free fatty acids and cholesterol. Correlations among the components were calculated and found to be statistically or directionally significant with few exceptions. The esterification reactions of jojoba, macadamia, and tall oils, along with a precise addition of squalene derived from , produced a suitable SSL mimetic. When applied to delipidized skin, the mimetic helped restore barrier function, increased skin hydration, and increased skin elasticity and firmness in aged skin.
The present research indicates that, overall, the SSL composition is quite consistent in a controlled population of 22-year-old females. Furthermore, there were strong correlations between the SSL components among subjects, with the exception of squalene and steryl esters. This was expected due to the fact that of the six major SSL components, steryl esters and squalene also showed higher variation over time for each individual. The variation in free fatty acids may be attributable to the potential differences in the microflora of the subjects. The variation in this study's results, as compared to previously published work, could indicate that the collection methods, geographic location, gender, and age specificity contribute to the distribution or collection of different lipid components on the skin surface. Since the excretion of sebum is known to decrease in females after 40 years of age, the proposed mimetic could be a beneficial supplement to human SSLs in aged skin, as well as in skin where the stratum corneum is defective, by aiding in the restoration of barrier function, while increasing skin hydration, elasticity, and firmness.
皮肤表面脂质（SSLs）对皮肤生理有重大影响，被认为参与体温调节、细菌定植、屏障功能及维持等皮肤生理过程。SSLs主要由脂肪酸、甘油三酯、胆固醇、甾醇酯、蜡酯和角鲨烯组成。本研究的目的是评估并更好地理解年龄和性别可控人群中SSLs的组成及变化，并制备一种合适的植物源模拟物。
从59名22岁健康女性的前额采集SSL样本，采用气相色谱 - 质谱联用（GC - MS）进行分析。使用来自[具体植物名称1]、[具体植物名称2]和[具体植物名称3]的植物源原料，通过一系列酯化反应制备模拟物，并采用GC - MS对脂质成分进行定量分析。甘油酯和蜡酯成分是在特定条件下通过[原料1]和[原料2]的酯交换反应生成的。甾醇酯成分是在类似条件下通过[原料3]的脂肪酸与植物甾醇的酯化反应生成的。
通过百分组成确定并定量了以下主要脂质类别：甘油酯、游离脂肪酸、角鲨烯、蜡酯、甾醇酯和胆固醇。各成分在受试者之间的变异性最小；然而，游离脂肪酸和胆固醇的变异性最大。计算了各成分之间的相关性，发现除少数例外情况外，在统计学上或方向上具有显著意义。霍霍巴油、澳洲坚果油和妥尔油的酯化反应，以及精确添加来自[具体来源]的角鲨烯，制备出了合适的SSL模拟物。将该模拟物应用于去脂皮肤时，有助于恢复屏障功能，增加皮肤水分含量，并提高老年皮肤的弹性和紧致度。
本研究表明，总体而言，在22岁女性这一可控人群中，SSLs的组成相当一致。此外，除角鲨烯和甾醇酯外，受试者之间SSLs各成分之间存在很强的相关性。鉴于在六种主要SSL成分中，甾醇酯和角鲨烯在个体随时间的变化中也表现出较高的变异性，这是可以预期的。游离脂肪酸的变异性可能归因于受试者微生物群的潜在差异。与先前发表的研究结果相比，本研究结果的差异可能表明采集方法、地理位置、性别和年龄特异性会影响皮肤表面不同脂质成分的分布或采集。由于已知40岁以后女性皮脂分泌会减少，因此所提出的模拟物对于老年皮肤以及角质层有缺陷的皮肤可能是一种有益的补充，有助于恢复屏障功能，同时增加皮肤水分含量、弹性和紧致度。
