TAURINE/ALOE VERA FOR BOOSTING ANTI-SKIN IRRITATION EFFECTS 217 maximum UV/Vis intensity at 470 nm and has high specifi city. Precolumn derivatization was performed as described in Pencheva et al. (18). Separation was performed using an isocratic elution with TBAB/phosphate (0.01 M/0.08 M) buffer: acetonitrile (70:30, v/v) mobile phase with a fl ow rate of 1 ml/m at a 7 m runtime. Chromatographic separations were performed on a Zorbax C18 (4.6 × 150 mm, 5 μ) column. Data were collected with an Agilent 1200 G1310A Isocratic pump, G1329A Autosampler, G1314B Variable Wavelength Detector. Analysis was performed with Agilent Chemstation software (Agilent Technologies, Inc., Wilmington, DE). Concentration of taurine was calculated based on peak area by using a regression curve constructed from a six-point (10.43–208.8 ppm) taurine calibration curve. Standard solutions were prepared from a stock taurine solution and regression curve had a correlation coeffi cient of 0.991. SIZE-EXCLUSION CHROMATOGRAPHY (SEC–HPLC) To ensure taurine and aloe extract did not affect the high effi cacy of AlCl3 antiperspi- rant salt, the size distribution of aluminum salt in aqueous solutions was monitored by SEC or SEC–HPLC. Retention times for each of the peaks may vary depending on ex- perimental conditions but they remain relative to each other. Water®600 analytical pump and controller, Rheodyne®7725I injector using a Protein-Pak® 125 (Waters) column, and Waters 2414 Refractive Index Detector were used to collect SEC data. The mobile phase was a 5.56 mM nitric acid solution, pH of 2.3 (with KNO3), with a fl ow rate of 1.0 ml/min. Analysis was conducted using Waters® Empower software (Waters Corporation, Milford, MA). Peak distribution for aluminum salt in our prototype AlCl3 formulation was observed to be similar to a 1.2% AlCl3 in DI water solution, which suggests that taurine and aloe extract would not affect the high effi cacy of AlCl3 salt. When the extraction of AlCl3 from our prototype product for SEC was conducted, the concentration of AlCl3 is reduced. However, the elution time for the aluminum peaks are the same, which indicates that the aluminum chloride is intact. If taurine and aloe extract hydrolyze aluminum chloride to large, insoluble aluminum hydroxide species, we would expect multiple peaks to elute before the aluminum chloride peak but we only observe one aluminum peak, peak 5, at a retention time of ca. 9.0 min (Figure 1). CLINICAL STUDY DESIGN A human clinical study was conducted to compare the anti-irritating properties of taurine and aloe extract in a 12% AlCl3 antiperspirant prototype product to a 12% com- mercial AlCl3 antiperspirant product. The study enrolled six male and six female subjects (n = 12) and lasted 4 days. Each subject was treated with both products (one on each desig- nated forearm area) in a randomized design. A 5 cm by 5 cm area was marked on both forearms where the prototype product and benchmark product were applied. Dosage for both products was 3 mg/cm2. Products were applied once a day, for four consecutive days in the mornings and were left on the skin overnight. Skin surface samples were collected at least 24 h after the fourth application to analyze for IL-1α levels. Skin surface samples were collected by using the cup-scrubbing method. A hollow glass cylinder (8.5 cm2) was

JOURNAL OF COSMETIC SCIENCE 218 placed on the skin surface of the forearm and 1 ml of PBS was pipetted onto the skin. The PBS was stirred with a glass rod for 60 s. Afterwards the extract was collected in an Eppendorf tube. STATISTICAL ANALYSIS Statistical analysis was performed using the two-tailed Student’s T-test. p-values below 0.05 were considered as signifi cant. Figure 1. Size- exclusion chromatography aluminum salt size distribution profi le of 1.2% AlCl3 solution and prototype 12% AlCl3 formulation with 0.1% taurine and 0.1% aloe extract (w/w).