JOURNAL OF COSMETIC SCIENCE 58 0.08 and 0.11 mg/cm2, respectively. The remainder was located at depths less than 6 μm. Slightly less of SA in Product B deposited at the surface, though the difference is not statistically signifi cant. In contrast, a signifi cantly higher fraction of SA, about 12% (0.013 mg/cm2) penetrated to the 6-μm depth over the course of the fi rst 4 h, the rest being distributed between the surface and 6 μm. The corresponding amounts for Prod- ucts A and C–E were 0% and 2%, respectively. Deeper penetration after 4 h may not have occurred in the case of product B because the ethanol eventually evaporated or otherwise dissipated in the stratum corneum. Lowered ethanol content with time would result in a lowered solubility of SA and increasing lateral packing effi ciency of the lipids, preventing further penetration. Lowered ethanol content with time would result in a lowered solu- bility of SA and increasing lateral packing effi ciency of the lipids, preventing further penetration. Other specifi c interactions within the product matrix are expected to be important. For example, the relative amount of binding to polymers by SA and ethanol can infl uence the availability of either one of these. CONCLUSION Penetration differences of SA into skin for different antiacne formulae have been observed in vivo in human subjects using confocal Raman spectroscopy. The penetration distribu- tion in the stratum corneum for an antiacne moisturizing cream and for low-alcohol (10%) toners were similar, with most of the SA remaining on the skin surface. Virtually no penetration was evident at a depth of 6 μm. In the case of a 40% alcohol-containing gel, however, 12% of the SA had penetrated to a depth of 6 μm after 4 h. These results are consistent with the known penetration-enhancing properties of ethanol. However, the matrix in which SA is contained, how SA binds to this matrix, and pH, are also important. REFERENCES (1) L. Rhein, B. Chaudhuri, N. Jivani, H. Fares, and A. Davis, Targeted delivery of salicylic acid from acne treatment products into and through skin: Role of solution and ingredient properties and relationships to irritation, J. Soc. Cosmet. Chem., 55, 65–80(2004). (2) H. Trommer and R. H. H. Neubert, Overcoming the stratum corneum: The modulation of skin pene- tration. A review, Skin Pharmacol. Physiol., 19, 106–121 (2006). Figure 3.

J. Cosmet. Sci., 68, 59–67 ( January/February 2017) 59 A botanically derived skin surface lipid mimetic based on the composition of healthy 22-year-old females JEFF ADDY, TIFFANY OLIPHANT, and ROBERT HARPER, Floratech, Chandler, AZ 85225 ( J.A., T.O.), and Harper & Associates, La Jolla, CA 92037 (R.H.). Synopsis Introduction: 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. Methods: 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 Macadamia integrifolia, Simmondsia chinensis, and Olea europaea, a mimetic was engineered via a series of esterifi cation reactions and lipid components quantitated with GC-MS. The glyceride and wax ester components were produced by the interesterifi cation of M. integrifolia and S. chinensis under specifi ed conditions. The steryl ester component was produced by the esterifi cation of the fatty acids of M. integrifolia and phytosterols under similar conditions. Results: The following major classes of lipids were found and quantifi ed 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 signifi cant with few exceptions. The esterifi cation reactions of jojoba, macadamia, and tall oils, along with a precise addition of squalene derived from O. europaea, produced a suitable SSL mimetic. When applied to delipidized skin, the mimetic helped restore barrier function, increased skin hydration, and increased skin elasticity and fi rmness in aged skin. Discussion: 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 specifi city 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 benefi cial supplement to human SSLs in aged skin, as well as in skin where the stratum Address all correspondence to Tiffany Oliphant at tiffany.oliphant@fl oratech.com. Presentation: This article was presented as a research podium at the 29th IFSCC Congress in Orlando, FL, October 30–November 2, 2016.