Antioxidant Activity of Heated Radish (Raphanus sativus L.) and Tyrosinase Inhibition

This study evaluated the antioxidant activity and tyrosinase inhibitory effects of heated radish (Raphanus sativus L.). The ethyl acetate fraction of the heated extracts markedly increased total polyphenol content and antioxidant activity. It also strongly suppressed tyrosinase and melanin biosynthesis, without exerting toxicity in B16F10 melanoma cells. It effectively suppressed the levels of key melanogenesis-related proteins, including microphthalmia-associated transcription factor (52.59%), tyrosinase (38.32%), tyrosinase-related protein (TRP)-1 (45.93%), and TRP-2 (50.26%). A series of chromatographic and spectroscopic analyses identified 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one as the major bioactive compound. It was characterized as a Maillard reaction product of the interactions between sugars and amino acids during heating, notably inhibiting tyrosinase. These results indicate that the ethyl acetate fraction of heated radishes holds potential as a natural ingredient in functional foods with anti-melanogenic activity.