Synthesis and Bioactivity Study of Mannich Base Derivatives of Ferulic Acid as a Tyrosinase Inhibitor and Antioxidant

Ferulic acid is reported to have antioxidant and anti-tyrosinase. However, it tends to change its colour because of undergoes autooxidation, decarboxylation, and dimerization. Structural modification through Mannich base substitution could change the compound's physicochemical properties and biological activity. This study aims to synthesize novel Mannich base derivatives of ferulic acid (3a-f) and evaluate them for their tyrosinase inhibitory and antioxidant activity. The study indicated that all the compounds exhibited tyrosinase inhibitor and antioxidant activity. Compound 3b has the highest tyrosinase inhibitory activity (IC50: 312.60 µM), higher than ferulic acid (IC50: 345.95 µM) but lower than a standard used (kojic acid, IC50: 46.34 µM). Compound 3e has the highest antioxidant activity (IC50:15.98 µM), higher than ferulic acid (IC50: 22.04 µM), and equal to ascorbic acid used as standard (IC50: 15.26 µM).