TAURINE/ALOE VERA FOR BOOSTING ANTI-SKIN IRRITATION EFFECTS 221 and IL-8 levels compared with formulations without taurine and aloe (p 0.05). These results suggest that the boosted anti-irritating effect of the taurine and aloe extract blend are kept intact even in dermatological vehicle. CELLULAR TAURINE ACCUMULATION To investigate the mechanism of the interaction between taurine and aloe extract, accu- mulation of taurine in EpiDerm keratinocytes was assessed. EpiDerm tissue was lysed after set time points and taurine concentration was measured by HPLC. After 2 h of treatment with solutions containing only taurine or both taurine and aloe extract, similar intracellular taurine levels were observed (Figure 7). However, after 6 h of treatment, dif- ferential intracellular taurine levels were observed and after 24 h there is a twofold, sta- tistically signifi cant difference in intracellular taurine levels (p 0.05). Our results reveal increased taurine accumulation in keratinocytes co-treated with aloe extract. Therefore, it Figure 3. Cell via bility data were obtained from the MTT assay and reported as % of the untreated negative control (NC).

JOURNAL OF COSMETIC SCIENCE 222 suggests that aloe extract increases the absorption of taurine by keratinocytes, which offers an explanation for the observed, signifi cant increase in anti-irritating effects. HUMAN CLINICAL STUDY DATA A clinical study involving 12 subjects was conducted with a prototype AlCl3 antiperspi- rant formulation containing 0.1% taurine and 0.1% aloe extract to assess the predict- ability of our in vitro results in vivo. Subjects were treated with two products, a commercial 12% AlCl3 antiperspirant product and a 12% AlCl3 test product containing taurine and aloe extract. These two products were the same products that were assessed in vitro using the EpiDerm model. After repeated application on the same area for a period of 4 d, we observed a statistically signifi cant difference in IL-1α levels between the two products Figure 4. IL-1α con centrations in EpiDerm cell culture media (n = 3) after topical application of solutions containing AlCl3 and actives for 1 h. Negative control (NC) was untreated tissue and positive control (PC) was tissue treated with 14% AlCl3 solution without taurine or aloe extract. EpiDerm tissue was treated with 14% AlCl3 solution containing either taurine or aloe extract or both. *p 0.05.