INHIBITORY EFFECTS OF KOREAN INDIGENOUS PLANTS 151 IN VITRO TYROSINASE INHIBITION RATE AND L-DOPA AUTO-OXIDATION INHIBITION RATE For this test, EtOAc fractions of S. china, P. lactifl ora, P. frutescens, E. alatus, P. mume, and P. trifoliata MC fraction of P. lactifl ora and n-BuOH fractions of E. offi cinalis and H. cordata were selected. Samples were dissolved in ethanol and the in vitro tyrosinase inhibition test was conducted using mushroom tyrosinase with arbutin, a depigmenting substance widely used in Korea, as a control. The results are shown in Figure 2. Figure 2. Inhibitory effects of S. china EtOAc fraction, P. lactifl ora EtOAc fraction, P. lactifl ora MC fraction, E. offi cinalis BuOH fraction, P. umbellatus EtOAc fraction, E. alatus EtOAc fraction, P. frutescens EtOAc fraction, H. cardata BuOH fraction, P. mume EtOAc fraction, P. trifoliata EtOAc fraction, and arbutin on (A) tyrosinase activity, (B) L -DOPA auto-oxidation, and (C) melanin synthesis. Results are shown as the aver- ages ± SD of three independent experiments.

JOURNAL OF COSMETIC SCIENCE 152 As shown in Figure 2A, the 10 selected extracts showed a pattern in which an increase in concentration was correlated with an increase in the tyrosinase inhibition effect. In par- ticular, EtOAc fractions of S. china, P. lactifl ora, E. alatus, and P. frutescens showed better inhibition effects than arbutin (positive control). IC50 values obtained from in vitro tyrosinase inhibition tests are presented Table II. As shown in Figure 2B, EtOAc fractions of S. china, P. lactifl ora, and E. offi cinalis showed the pattern in which an increase in concentration was correlated with an increase in the L -DOPA auto-oxidation inhibition effect. However, the inhibitory effect of L -DOPA auto-oxidation was less than that of tyrosinase. The other samples showed an inhibitory effect below 50%, even at a concentration of 1%. IN VITRO MELANIN SYNTHESIS INHIBITION For this study, a total of 10 fractions (EtOAc fractions of S. china, P. lactifl ora, P. umbellatus, E. alatus, P. frutescens, P. mume, and P. trifoliata MC extract of P. lactifl ora and n-BuOH fractions of E. offi cinalis and H. cordata) were dissolved in ethanol, and in vitro melanin synthesis inhibition tests were conducted using mushroom tyrosinase with arbutin as a control. As shown in Figure 2C, the 10 selected fractions showed the pattern in which an increase in concentration was correlated with an increase in the melanin synthesis inhibi- tion effect. In particular, EtOAc fractions of S. china, P. lactifl ora, P. umbellatus, P. mume, and P. trifoliata MC fraction of P. lactifl ora and n-BuOH fraction of E. offi cinalis showed better inhibition effects than arbutin (positive control). The IC50 values obtained from in vitro tyrosinase inhibition tests are presented in Table II. As a result of the screening test, the 10 selected fractions were used in three in vitro de- pigmenting effi cacy tests: tyrosinase inhibition test, L -DOPA auto-oxidation inhibition test, and melanin synthesis inhibition test. EtOAc fractions of S. china, P. lactifl ora, and P. umbellatus and BuOH fraction of E. offi cinalis showed better inhibition effects than arbutin for two or more types of effi cacy tests. Table II IC50 on Tyrosinase Activity and Melanin Synthesis Samples Fraction IC50 (%) Tyrosinase activity Melanin synthesis Smilax china EtOAc 0.023 0.141 Paeonia lactifl ora EtOAc 0.073 0.085 P. lactifl ora MC 0.266 0.117 Evodia offi cinalis BuOH 0.296 0.146 Polyporus umbellatus EtOAc 0.101 0.209 Euonymus alatus EtOAc 0.055 0.330 Perilla frutescens EtOAc 0.077 0.295 Houttuynia cordata BuOH 0.685 0.239 Prunus mume EtOAc 0.213 0.119 Poncirus trifoliata EtOAc 0.167 0.147 Arbutin — 0.087 0.229