The purposes of this study were to evaluate the inhibitory potential of 500 mg/L ethanol extract from the seed coat of black soybean (Glycine max (L.) Merrill, Tainan No. 3) (BSSCEE) toward the activity of tyrosinase, otherwise human malignant melanoma A375.S2 cell line was used to assess the in vitro effect of BSSCEE on the melanogenesis. The results of inhibitory effects on mushroom tyrosinase activity showed that BSSCEE could inhibit the activity of mushroom tyrosinase. At the same concentration (1.66 mg/ml) between BSSCEE and 500 mg/L ethanol extract from the whole black soybean (WSSEE), the inhibition rate of BSSCEE better than WSSEE exceed in double. Indicate that the most of inhibitors on mushroom tyrosinase were existed in the seed coat of black soybean. Otherwise the inhibition rate was depend on the concentration of BSSCEE and the inhibition mechanism was belong to mixed-type inhibition. The results of cell culture were showed that there was the tyrosinase ability to catalyze L-dopa during human malignant melanoma A375.S2 cell line. After treated with different concentrations of BSSCEE, using three different concentrations of L-dopa (0.05, 0.25 and 0.5 mg/ml) to evaluate. Among all of results the highest two concentrations of BSSCEE (20 μg/ml and 30 μg/ml) showed the more significant inhibitory effect on human malignant melanoma A375.S2 cell line.
