PURPLE SWEET POTATO EXTRACTS IN UV PROTECTION 337 The DPPH radical scavenging activity of the anthocyanin extracts was measured as the decrease in absorbance of DPPH at a wavelength of 517 nm. Figure 2 shows the results that were plotted as a function of anthocyanin extracts. The DPPH radical scavenging activity increased with increasing anthocyanin extract content. The difference was more signifi cant when the anthocyanin extract content was less than 2%. Anthocyanins ex- tracted by using acidic ethanol had a better radical scavenging activity. With a high antho- cyanin extract content, the DPPH radical scavenging activity was approximately 78% for acidic ethanol extracts. The DPPH radical scavenging activity of acidic ethanol and acidic water extracts was signifi cantly different ( p 0.05) at 0.25%, 1.25%, 2.5%, and 5% anthocyanin extract content. The anti-oxidative activity can be represented by the EC50 value, and the results are shown in Table I. The EC50 values of acidic ethanol and water extracts were 1.63 ± 0.14% and 3.32 ± 0.22%, respectively. The results revealed that the acidic ethanol extract had better radical scavenging activity than the acidic water extract. The total phenolic content of the acidic ethanol and acidic water extracts of TNG73 purple sweet potato was expressed as μg GAE/ml sample, and the results are shown in Table II. When 10% extracts were used, the phenolic content analysis results were 97.26 ± 9.07μg/ml and 80.95 ± 8.86 μg/ml for acidic ethanol- and water-extracted sam- ples, respectively. In addition, the phenolic content of the acidic ethanol extract was always higher than that of the acidic water extract. The reducing ability measured as the change in absorbance with a 700-nm wavelength correlated to the anti-oxidative ability of the anthocyanins. The higher reducing ability Figure 2. 1,1-diphenyl- 2-picrylhydrazyl (DPPH) radical scavenging activity of acidic ethanol (AE)- and acidic water (AW)-extracted anthocyanin solutions. Each value is the mean ± SD (n=3) of the measurements performed. *Indicates a signifi cant difference ( p0.05) between the two groups. Table I The EC50 Values of Acidic Ethanol (AE) and Acidic Water (AW) Extracts of Purple Sweet Potato EC50 value (%) AE extract 1.63 ± 0.14 AW extract 3.32 ± 0.22 Ascorbic acida 82.5 ± 3.3 a The unit of EC50 of ascorbic acid is μg/ml.

JOURNAL OF COSMETIC SCIENCE 338 represented the stronger anti-oxidative ability. Figure 3 shows the effect of anthocyanin extracts on the reducing ability of anthocyanins that were extracted using acidic ethanol and acidic water. The reducing ability of acidic ethanol and water extracts was signifi cantly dif- ferent (p 0.05) at 1.25%, 5%, and 10% of anthocyanin extract content. The relationship between the reducing ability and anthocyanin content was almost linear. Thus, using more anthocyanin extracts resulted in a better reducing ability. Meanwhile, the acidic ethanol-extracted anthocyanins showed a higher reducing ability compared to acidic water-extracted anthocyanins. According to the above results, using more anthocyanin extracts resulted in better DPPH radical scavenging activity, higher total phenolic content, and higher reducing ability. The acidic ethanol-extracted anthocyanins were good anti-oxidative ingredients for the cosmetic cream. Adding anthocyanin extracts to the cosmetic cream not only provides ultra-UV protective ability, but also helps skin against free radicals. Figure 4 shows the UV absorption ability of a cosmetic cream at different wavelengths measured by the spectrophotometric method. The addition of anthocyanin extract dra- matically improves the UV-absorbing ability of the cosmetic cream for both UV-A (350 and 375 nm) and UV-B (300 and 325 nm), with the improvement being more signifi cant for the UV-B. The cosmetic cream with the anthocyanin extract was more effective for UV-B absorbance than for UV-A. The results revealed that anthocyanin extracts are ideal Table II Total Phenolic Content of Acidic Ethanol (AE) and Acidic Water (AW) Extracts of Purple Sweet Potato Total phenolic content (μg gallic acid equivalent/ml sample) Extract added (%) 1.25% 2.5% 5% 10% AE extract 14.08 ± 1.61∗ 27.38 ± 1.83∗ 56.26 ± 7.34 97.26 ± 9.07 AW extract 8.96 ± 1.25 18.60 ± 1.62 47.19 ± 5.16 80.95 ± 8.86 Each value is mean ± SD (n=3). ∗Indicates a signifi cant difference ( p 0.05) between the two groups. Figure 3. Reducing ability of acidic ethanol (AE)- and acidic water (AW)-extracted anthocyanin solutions. Each value is the mean ± SD (n=3) of the experiments performed. *Indicates a signifi cant difference ( p0.05) between the two groups.