Synthesis and structure-activity relationships of phenylpropanoid amides of serotonin on tyrosinase inhibition.

In this manuscript, we synthesized a series of phenylpropanoid amide of serotonin 1-9, analyzed their structural importance for two biologic activities (antioxidant activity and tyrosinase inhibitory activity). While the serotonin moiety and the amide linkage of serotonin derivatives affect antioxidant activity strongly, the serotonin moiety, the amide linkage and the cinnamic acid moiety affect tyrosinase inhibitory activity. Among tested compounds, compound 4 which contains cathechol moiety exhibited the most antioxidant activity (EC(50) = 19.4 ± 2.0 μM), and compound 6 exhibited significant tyrosinase inhibitory activity (IC(50) = 5.4 ± 3.6 μM). Our data suggests that a useful clue for the design and development of new tyrosinase inhibitors.