Synthesis of Cinnamic Acid-Coumarin Ester Analogs and Inhibition of Tyrosinase Activity

Abstract

In medicinal chemistry, the structural modification of natural product and skeleton hybridization strategies is important way to improve the biological activity of template compound and find highly active lead compounds. In this work, two series of cinnamic acid-coumarin ester analogs were synthesized by using cinnamic acid and hydroxycoumarin as raw materials. And the tyrosinase inhibitory activity of the synthesized compounds was evaluated. The results indicated that the cinnamic acid-coumarin analogs had favourable tyrosinase inhibitory activity, especially 2-oxo-2H-benzopyran-4-yl(E)-3-(4-hydroxyphenyl)propenyl ester (C8), 2-oxo-2H-benzopyran-7-yl(E)-3-(4-hydroxyphenyl)propenyl ester and (D8) with IC50 of (10.7±0.7) and (2.2±0.2) μmol•L-1, respectively, which are 3 and 13 times that of kojic acid (IC50 (28.5±1.1) μmol•L-1). The structure-activity relationship analysis results showed that the introduction of substituents like F, Cl, and OH could efficiently enhance the tyrosinase inhibitory activity, and the inhibitory activity of condensation product of substituted cinnamic acid with 7-hydroxycoumarin was higher than that of substituted cinnamic acid with 4-hydroxycoumarin. Kinetic studies showed that the inhibitions of tyrosinase by compounds C8 and D8 are reversible mixed-type inhibitory effects. KI values of C8 and D8 were 1.07 and 20.61 μmol•L-1, respectively, and KIS values were 3.72 and 27.09 μmol•L-1, respectively. Finally, molecular docking was carried out to simulate the docking between compounds C8 and D8 with tyrosinase.