In this study, 5-hydroxyindole-based i-melanin was biosynthesized through enzymatic reactions catalyzed by flavin monooxygenase (FMO) and sequential MelC tyrosinase. The monomer underwent intracellular random polymerization, resulting in a novel symmetric melanin. The synthesized i-melanin exhibited a significantly darker black coloration compared to conventional melanin and demonstrated enhanced biological activities, including antioxidant and antibacterial properties. The physical and biological characteristics of i-melanin were analyzed using UV/Vis spectroscopy, ABTS assays, and growth inhibition studies. Notably, i-melanin displayed antifungal activity against Candida albicans. For functional applications, i-melanin was formulated as a hair dye and incorporated into a UV-protection cream through complexation with ZnO. Both formulations exhibited excellent dyeing efficacy and UV-blocking performance. Given the high production yield of i-melanin, its scalability for industrial applications appears promising. These findings suggest that this novel melanin has potential for integration into various functional products in the future.
This work was supported by the National Research Foundation (NRF) of Korea grant funded by the Ministry of Education, Science, and Technology (MEST) [2021R1A2C1007519] and the R&D Program of MOTIE/KEIT [grant numbers: 20025698 and 20018132].
