This study evaluated the whitening effects of flavonoids extracted from Petasites japonicus root (PJR) using in vitro and cell-based assays to assess their cytoprotective, enzyme-inhibitory, and melanogenesis-suppressive activities. PJR flavonoids (30~60 μg/mL) showed no cytotoxicity and slightly enhanced cell proliferation at 40 μg/mL. Sodium nitroprusside (0.3 mM) decreased cell viability to 31%, whereas PJR restored it to 68.3%. PJR exhibited dose-dependent α-glucosidase inhibition (20.3~63.2%), indicating its potential to modulate skin glycation and pigmentation. In the malondialdehyde inhibition assay, PJR reduced lipid peroxidation by 35~60%, further supporting its antioxidative capacity. 3,4-Dihydroxyphenylalanine oxidation was suppressed by up to 68.9%, indicating reduced formation of the melanin precursor. The tyrosinase activity decreased from 145% to 86.9% and melanin synthesis was reduced from 105% to 66.9% in a concentration-dependent manner, showing a whitening efficacy comparable to that of arbutin. Overall, these findings indicate that PJR flavonoids possess antioxidative, antiglycation, and antimelanogenic properties and offer strong potential as safe multifunctional ingredients for functional cosmetic and food applications.

Abstract
Introduction
Materials and Methods
    1. Sample preparation
    2. Cell viability and inhibitory activity of reactive oxygenspecies generation
    3. α-Glucosidase inhibitory activity
    4. Malondialdehyde inhibitory activity
    5. Inhibitory activity of DOPA oxidation
    6. Tyrosinase Inhibitory activity in B16F10 cells with α-MSH
    7. Inhibitory activity of α-MSH-induced melanin production
    8. Statistical analysis
Results and Discussion
    1. Effect of PJR flavonoids on cell viability
    2. Effects of PJR flavonoids on α-glucosidase inhibitoryactivity in a cell-free system
    3. Effects of PJR flavonoids on malondialdehydeinhibitory activity in a cell-free system
    4. Effects of PJR flavonoids on DOPA oxidationinhibitory activity in a cell-free system
    5. Effects of PJR flavonoids on tyrosinase inhibitoryactivity in B16F10 cells with α-MSH
    6. Effects of PJR flavonoids on inhibitory activity ofmelanin production in B16F10 cells with α-MSH
Conclusion
References

• Hyun-Suk Choi(Associate Professor, Dept. of Hotel Culinary Arts Patissier, Chungcheong University, Cheongju 28171, Korea)
• DuBok Choi(Professor, Dept. of Science and Technology Convergence, Graduate School of Chosun University, Gwangju 61452, Korea) Corresponding author