:::) BREADFRUIT EXTRACT AS SKIN LIGHTENER (A) 1500 1000 500 0 .I 0 (B) 400 200 0 0 5 5 artocarpin 10 Minutes artocarpin 10 Minutes 15 15 47 20 20 Figure 2. Chromatograms of (A) 0.5 mg/ml of A. incisus ether and (B) 1.0 mg/ml of methanol extracts. TYROSINASE-INHIBITORY ACTIVITY In this study, DMSO was used to dissolve the extracts. The percentage of tyrosinase inhibition of the ether extract and kojic acid are shown in Figure 3 and Table II. The IC 50 value of the ether extract was 10.26 ± 3.04 µg/ml, whereas that of kojic acid, a well-known lightening agent, was 7 .89 ± 0.18 µg/ml. Generally, the mode of inhibitory activity depends on the structure of both the substrate and inhibitor. In this study, such activity was concerned with the o-diphenolase inhibitory activity of mushroom tyrosi­ nase since 1-DOPA was used as the substrate (10,11). For this reason, similarly to kojic acid, the A. incisus extract behaves as an inhibitor of the diphenolase activity of tyros­ inase. Previously, it was found that artocarpin showed no inhibitory effect, according to a mushroom tyrosinase assay (3,4). The tyrosinase-inhibitory effect of the A. incisus ether

48 C 100 0 C iD a, lU 50 C "i 0 L. � � JOURNAL OF COSMETIC SCIENCE _ .. .. 0 +-------,,------r------,.-------, -1 0 1 2 Log concentration (µg/mL) 3 --A. incisus extract •• - • · Kojic acid Figure 3. Tyrosinase-inhibitory activity of A. incisus ether extract and kojic acid. Table II Inhibitory Effects on Tyrosinase Activity of Kojic Acid and A. incisus Ether Extract Concentration (µg/ml) 0.5 1 5 10 50 100 250 500 IC50 (µg/ml) Kojic acid 7.05 ± 0.08 7.02 ± 0.04 9.12 ± 0.11 26.54 ± 2.33 66.79 ± 0.53 81.94 ± 3.16 95.59 ± 0.55 96.08 ± 0.95 7.89 ± 0.18 Tyrosinase inhibition(%) A. incisus ether extract 20.13 ± 1.39 26.55 ± 1.13 42.76 ± 1.26 48.29 ± 0.93 67.44 ± 2.24 73.40 ± 1.42 81.25 ± 1.83 85.06 ± 4.24 10.26 ± 3.04 extract, therefore, may result from the action of the other compounds that are composed of such extract. ANTIOXIDANT ACTIVITY According to the DPPH radical scavenging activity, the EC 50 values of A. incisus extract and the positive controls are presented in Table III and IV. Each tested sample shows the dose-dependent curve for DPPH radical scavenging activity, as shown in Figure 4. The obtained results indicate that the A. incisus ether extract has antioxidant activity with an EC 50 of 169 ± 9.73 µg/ml. The extract of A. incisus heartwood provides weaker free­ radical scavenging activity than BHT and 1-ascorbic acid. In this study, the radical scavenging activity of the ether extract was tested using a methanolic solution of the stable free redical, DPPH. This solution exhibits a deep purple color with an absorption maximum at 515 nm. Antioxidant molecules can quench DPPH free radicals and convert them to a colorless/bleached product. The