TAURINE/ALOE VERA FOR BOOSTING ANTI-SKIN IRRITATION EFFECTS 219 RESULTS AND DISCUSSIONS DETERMINING THE OPTIMAL CONCENTRATION OF TAURINE AND ALOE EXTRACT Per cent AlCl3 (w/w) is the highest concentration allowed by the Food and Drug Ad- ministration in an over-the-counter product (19). Fourteen percent AlCl3 concentra- tion was selected to test for irritation because it is the highest concentration of AlCl3 we found in over-the-counter products. AlCl3 treatment alone resulted in a 5.0-fold increase in IL-1α levels compared with the untreated control. MTT assay to measure cell viability after treatment was used to normalize IL-1α data. In tissue that are co- treated with taurine or aloe extract at either 0.1% or 0.5% concentrations we ob- served drastic reductions in IL-1α levels, up to a 40% reduction (Figure 2). However, Figure 2. IL-1α concentrations 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 tissues were treated with 14% AlCl3 solution containing either taurine or aloe extract or both at varying concentrations to deter- mine the optimal ratio and concentration of actives.

JOURNAL OF COSMETIC SCIENCE 220 when tissue cultures were co-treated with both taurine and aloe extract at 0.1%, there is an even further reduction in IL-1α levels compared with the control and tissue treated with only taurine or aloe extract. Treatment with taurine and aloe extract at 0.1% concentrations resulted in a statistically signifi cant (p 0.05) reduction in IL-1α levels compared with treatment with just taurine or aloe extract at either 0.1% or 0.5% concentrations. Although EpiDerm tissue treated with 0.1% taurine and 0.1% aloe extract released lower levels of IL-1α compared with tissue treated with only tau- rine or aloe extract at 0.1% or 0.5% concentrations, the combined, boosted effects were not observed in EpiDerm tissue co-treated with 0.5% taurine and 0.5% aloe ex- tract. We found that at higher concentrations of aloe extract, the pH of the aqueous solution and formulations decreased signifi cantly because of the high percentage of malic and citric acid ( 18%). Thus, the concentration of aloe extract must be careful se- lected with regards to the pH. From this study, we were able to conclude that the 0.1% taurine and 0.1% aloe extract concentration would be the ideal concentration for our test products. BOOSTED ANTI-IRRITATING EFFECTS OF TAURINE AND ALOE EXTRACT BLEND After experiments were conducted to determine the optimal ratio and concentration of taurine and aloe extract, which was found to be a 1:1 ratio at 0.1% (Figure 2), we pro- ceeded to assess the irritancy potential of AlCl3 in a simple aqueous solution by measur- ing the levels of pro-infl ammatory cytokine, IL-1α, after treatment with or without the addition of the anti-irritating actives. AlCl3 treatment alone resulted in a 3.4-fold increase in IL-1α levels compared with the untreated control. MTT assay to measure cell viability after treatment was used to normalize IL-1α data (Figure 3). In tissue that are treated with 0.2% taurine or 0.2% aloe extract, we observed drastic reductions in IL-1α levels, up to a 50% reduction (Figure 4). However, when tissue cultures were co-treated with 0.1% taurine and 0.1% aloe extract, there is an even further reduction in IL-1α levels compared with the tissue treated with only taurine or aloe extract. Co-treatment with 0.1% taurine and 0.1% aloe extract resulted in a statistically signifi cant (p 0.05) reduc- tion in IL-1α levels compared with treatment with 0.2% taurine or 0.2% aloe extract. These results suggest that the blend of taurine and aloe extract leads to a signifi cant boost in their anti-irritating effects. TAURINE AND ALOE EXTRACT REDUCE IRRITATION POTENTIAL OF PROTOTYPE ALCL3 PRODUCT To further test the boosted anti-irritating effect of the taurine and aloe extract blend, prototype antiperspirant formulations containing AlCl3 with or without taurine and aloe extract was assessed for irritation potential. A commonly used 12% AlCl3 over-the- counter product was selected as a benchmark for irritation testing. Figures 5 and 6 illus- trate the results of IL-1α and IL-8 release assays after treatment of EpiDerm tissue with our prototype product and controls. Topical application of the benchmark product, 12% AlCl3 solution and prototype product results in signifi cantly increased levels of IL-1α and IL-8. However, when tissues are treated with prototype product containing 0.1% taurine and 0.1% aloe extract, we observed statistically signifi cant reductions in IL-1α