Figure 1. Chemical structure of isolated compounds from Campylotropis hirtella. 1. Inhibitory effects of compounds (1–j) on tyrosinase activities. L-tyrosine L-DOPA compound IC50 (M)a Inhibition type (Ki, M)b IC50 (M) Inhibition type (Ki, M) 1 2.90.3 Competitive (1.8) 128.20.5 Competitive (76.4) 2 92.00.2 Competitive (49.7) >200 - 3 0.030.006 Competitive (0.019) 0.50.003 Competitive (0.13) 18.40.5 Competitive (7.5) 144.01.2 Competitive (81.4) 4 a >200 - >200 - b >200 - >200 - c >200 - >200 - d >200 - 146.40.4 Competitive (56.67) e >200 - >200 - >200 - >200 - f g >200 - >200 - h >200 - >200 - i >200 - >200 - j >200 - >200 - Kojic acidc 13.20.8 Not tested 26.51.6 Not tested aAll compounds were examined in a set of experiments repeated three times; IC50 values of compounds represent the concentration that caused 50% enzyme activity loss. bValues of inhibition constant. cKojic acid is positive control.
Figure 1. Chemical structure of isolated compounds from Campylotropis hirtella. 1. Inhibitory effects of compounds (1–j) on tyrosinase activities. compound L-tyrosine L-DOPA IC50 (M)a Inhibition type (Ki, M)b IC50 (M) Inhibition type (Ki, M) 1 2 3 4 a b c d e f g h i j Kojic acidc 2.90.3 92.00.2 0.030.006 18.40.5 >200 >200 >200 >200 >200 >200 >200 >200 >200 >200 13.20.8 Competitive (1.8) Competitive (49.7) Competitive (0.019) Competitive (7.5) - - - - - - - - - - Not tested 128.20.5 >200 0.50.003 144.01.2 >200 >200 >200 146.40.4 >200 >200 >200 >200 >200 >200 26.51.6 Competitive (76.4) - Competitive (0.13) Competitive (81.4) - - - Competitive (56.67) - - - - - - Not tested aAll compounds were examined in a set of experiments repeated three times; IC50 values of compounds represent the concentration that caused 50% enzyme activity loss. bValues of inhibition constant. cKojic acid is positive control.
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