Germination Improves the Antioxidant and Anti-Melanogenic Properties of Resveratrol-Enriched DJ526 Rice in Melan-a Cells

Resveratrol is a natural polyphenolic compound with antioxidant and anti-melanogenic activities, but it occurs only at low levels in most edible plant tissues, motivating the development of enriched sources. Resveratrol-enriched DJ526 rice provides such a source, and seed germination may further modulate its biological activity. Therefore, this study investigated the effects of 5-day germination on the antioxidant and anti-melanogenic properties of resveratrol-enriched DJ526 rice in Melan-a cells. Seed extracts of ungerminated DJ526 (DJ526_0), germinated DJ526 (DJ526_5), and non-transgenic controls (DJ_0 and DJ_5) were evaluated for antioxidant capacity, cell viability, melanogenic activities, and the expression of MITF and its downstream targets. Five-day germination increased piceid and resveratrol content in DJ526_5 from 4.73 ± 0.06 to 16.90 ± 0.00 µg/g dry weight and from 2.60 ± 0.00 to 3.27 ± 0.06 µg/g dry weight, respectively. DJ526_5 exhibited the strongest antioxidant capacity (ABTS IC50, 16.81 ± 1.26 mg/mL). At 100 µg/mL, DJ526_5 reduced intracellular melanin content and tyrosinase activity to 59.48 ± 2.13% and 45.63 ± 0.24% of the control, respectively, without reducing cell viability. DJ526_5 also reduced the mRNA and protein expression of MITF, tyrosinase, TRP-1, and TRP-2. These findings support the potential of DJ526 as a functional ingredient for hyperpigmentation management.