Synthesis of p-coumaroyl amino acid derivatives and evaluation of their anti-oxidative and anti-tyrosinase activities

P-coumaroyl amino acid ethyl esters (p-CAAEEs, ãf) were successfully synthesized with p-coumaric acid (p-Coa) and amino acid ethyl ester hydrochloride under the catalysis of 1-ethyl-3- (dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 1-hydroxybenzotriazole (HOBt). The new derivatives were characterized by FT-IR, 1H NMR, and UPLC-MS spectroscopy techniques. The antioxidative activities of p-CAAEEs were evaluated in terms of scavenging capabilities of DPPH, hydroxyl and ABTS radicals. Among these compounds, d and f exhibited the stronger strength to scavenge free radicals. In addition, their anti-tyrosinase activities were determined through monophenolase and diphenolase experiments. In the anti-tyrosinase diphenolase experiment, all p-CAAEEs had stronger inhibitory abilities than that of p-Coa. In particular, compound f exhibited potential both anti-oxidative and anti-tyrosinase activities.