]. Cosmet. Sci., 57, 341-343 Quly/August 2006) Abstracts International Journal of Cosmetic Science Vol. 28, No. 2, 2006* Evaluation of in Vitro Antimicrobial Activity of Thai Basil Oils and their Micro-Emulsion Formulas Against Propionibacterium Acnes J. Viyoch*·t, N. Pisutthanant, A. Faikreua*·t, K. Nupangta*, K. Wangtorpol* and J. Ngokkuen* The aim of this study was to evaluate the efficacy of Thai basil oils and their micro-emulsions, on in vitro activity against Propionibacterium acnes. An agar disc diffusion method was employed for screening antimicrobial activity of the essential oils of Ocimum basilicum L. (sweet basil), Ocimum sanctum L. (holy basil) and Ocimum americanum L. (hoary basil) against P. acnes. Minimum inhibitory concentration (MIC) values of the basil oils were determined using an agar dilution assay. The obtained results indicated that the MIC values of sweet basil and holy basil oils were 2.0% and 3.0% v/v, respectively, whereas hoary basil oil did not show activity"against P. acnes at the highest concentration tested (5.0% v/v). Gas chromatography­ mass spectrometry anal ys is revealed that methyl chavicol (93.0%) was the major compound in sweet basil oil, and eugenol (41.5%), y-caryophyllene (23.7%) and methyl eugenol (11.8%) were major compounds in holy basil oil. Hoary basil oil contained high amounts of geraniol (32.0%) and neral (27.2%) and small amounts of methyl chavicol (0.8%). The Oil-in-water (o/w) micro-emulsions of individual basil oils with concentrations corresponding to their MIC values were formulated. The stable o/w micro-emulsion system for basil oil consisted of 55.0% v/v water phase, 10.0% v/v oil phase (2.0 or 3.0% v/v sweet basil or 3.0% v/v holy basil oil plus 7.0% v/v isopropyl myristate), 29.2% v/v polysorbate 80 and 5.8% v/v 1,2-propylene glycol. Hydroxyethylcellulose at a concentration of 0.5% w/v was used as thickening agent. According to the disc diffusion assay, the formulations containing sweet basil oil exhibited higher activity against P. acnes than those containing holy basil oil, and the thickened formulations tended to give a lower activity against P. acnes than the non-thickened formulations. The prepared micro-emulsions were stable after being tested by a heat-cool cycling method for five cycles. These findings indicate the possibility to use Thai sweet and holy basil oil in suitable formulations for acne skin care. Study On the Transferability of the Time Temperature Superposition Principle to Emulsions M. Muehlbach*, R. Brummer* and R. Eggerst The instability of emulsions is basically clarified by a phase separation. The separated phase can either cream or sediment. Destabilization is mostly compounded by coalescence and gives a first indication through extension of droplets. In the cosmetics industry as well as many other branches of industry such as the food industry and paint and coatings industry, product stability is one of the most i mp ortant quality criteria Many stability tests have already been performed with the widest variety of methods from different fields of technology. In research and development it is especially important to obtain quick results on the stability of a formulation. Such results represent a tool that can help developers find an optimal formulation in a short time. In addition, they can shorten development times, leading to quicker introduction of a product in the market. Moreover, they can help to reduce storage stability tests to minimum, making less climatized rooms, space and work required to predict shelf-lives. The cycle test is an example of such a method developed in the field of rheology [1 ]. In this test the sample is subjected to continuously changing temperatures and its behavior observed. However, other methods can also conceivably used to predict stabilities. The aim of this work is to find a new model to predict the long-term stability. This model should be based on empirical data and it should determine the applicability of the time temperature superposition (TIS) principle to emulsions. * These abstracts appear as they were originally published. They have not been edited by the Journal of Cosmetic Science. 341

342 JOURNAL OF COSMETIC SCIENCE Ethnic Skin Types: Are There Differences in Skin Structure and Function? AV. Rawlings People of skin of colour comprise the majority of the world's population and Asian subjects comprise more than half of �he total population of the earth. Even so, t�e literature on the characteristics of the subjects with skin of colour is limited. Several groups over the past decades have attempted to decipher the underlying differences in skin structure and function in different ethnic skin types. However, most of these studies have been of small scale and in some studies interindividual differences in skin quality overwhelm any racial differences. There has been a recent call for more studies to address genetic together with phenotypic differences among different racial groups and in this respect several large-scale studies have been conducted recently. The most obvious ethnic skin difference relates to skin colour which is dominated by the presence of melanin. The photoprotection derived from this polymer influences the rate of the skin aging changes between the different racial groups. However, all racial groups are eventually subjected to the photoaging process. Generally Caucasians have an earlier onset and greater skin wrinkling and sagging signs than other skin types and in general increased pigmentary problems are seen in skin of colour although one large study reported that East Asians living in the U.S.A. had the least pigment spots. Induction of a hyperpigmentary response is thought to be through signaling by the protease-activated receptor- 2 which together with its activating protease is increased in the epidermis of subjects with skin of colour. Changes in skin biophysical properties with age demonstrate that the more darkly pigmented subjects retaining younger skin properties compared with the more lightly pigmented groups. However, despite having a more compact stratum corneum (SC) there are conflicting reports on harrier function in these subjects. Nevertheless, upon a chemical or mechanical challenge the SC harrier function is reported to be stronger in subjects with darker skin despite having the reported lowest ceramide levels. One has to remember that barrier function relates to the total architecture of the SC and not just its lipid levels. Asian skin is reported to possess a similar basal transepidermal water loss (TEWL) to Caucasian skin and similar ceramide levels hut upon mechanical challenge it has the weakest harrier function. Differences in intercellular cohesion are obviously apparent. In contrast reduced SC natural moisturizing factor levels h�ve been reported compared with Caucasi�n and African American skin. These differences will contribute to differences in desquamation hut few data are available. One recent study has shown reduced epidermal Cathepsin L2 levels in darker skin types which if also occurs in the SC could contribute to the known skin ashing problems these subjects experience. In very general terms as the desquamatory enzymes are extruded with the lamellar granules subjects with lowered SC lipid levels are expected to have lowered desquamatory enzyme levels. Increased pores size, sehum secretion and skin surface microflora occur in Negroid subjects. Equally increased mast cell granule size occurs in these subjects. The frequency of skin sensitivity is quite similar across different racial groups hut the stimuli for its induction shows subtle differences. Nevertheless, several studies indicate that Asian skin maybe more sensitive to exogenous chemicals probably due to a thinner SC and higher eccrine gland density. In conclusion, we know more of the biophysical and somatosensory characteristics of ethnic skin types hut clearly, there is still more to learn and especially about the inherent underlying biological differences in ethnic skin types. An Interlahoratory Comparison of Methods Used to Assess Antioxidant Potentials J. Buenger*, H. Ackermann•, Mehling!:, I. Pfitzner§, K.-A. Schroeder1[ and U. Wollenweber"'* A. Jentzscht, A. Reiffen*, K.-R. Many analytical methods are used to measure the antioxidative activity of substances yet little is known about the comparability of the test results between laboratories. After an initial evaluation of a broad range of methods conducted by one laboratory, the 2,2- diphenyl-1-picrylhydrazyl (DPPH) assay, the trolox equivalent antioxidant capacity (TEAC) assay, the lipid assay (or 2,2'-azohis(2-aminepropane) (ABAP) assay) and the thiobarhituric acid (TBA) assay were selected to be evaluated in the interlaboratory study. The antioxidative potentials of trolox, tocopherol, lipochroman-6, ascorbic acid, 4-methyl-hrenzcatechin, and/or 3,5-di-tert-butyl-4-hydroxytoluene (BHT) were assessed using each of the methods. These methods were then evaluated in respect of their reproducibility and classification properties. Based on the results of this study, the DPPH assay followed by the TEAC assay yielded the best results based on reproducibility and sensitivity both within one laboratory and between laboratories. The results of the interlahoratory study were then compared with the single center results obtained from the commercially available photochemolumiescence (PCL) kit. To assess the transferability of chemical data to biological systems, they were also compared with the single center results obtained using the cell-based Dichlorodihydrofluoresceine (DCFH) assay. Transfollicular Delivery of Linoleic Acid in Human Scalp Skin: Permeation Study and Microautoradiographic Analysis V. Raufast and A. Mavon There are a large number of studies on the pharmacological activity of lineolic acid (LA) on the skin however, very little work has been carried out to