Abstract:
Enhancing nutritional value and bioactivity through microgreen technology and plant sprouting is receiving increasing attention in the food, cosmetic, health, and agricultural industries. This study aimed to evaluate the effects of the germination period of radish sprouts (Raphanus sativus L.) on changes in total phenolic content, total flavonoid content, and antioxidant activity for potential use in cosmetics. Radish seeds were germinated for 0, 3, 5, 7, and 9 days and then extracted using three solvents: water, ethanol, and acetone. The total phenolic and flavonoid contents were determined using the Folin-Ciocalteu and aluminum chloride colorimetric methods. Antioxidant activity was assessed through DPPH radical scavenging and ferric reducing antioxidant power (FRAP) assays. The results showed that increased sprout age significantly increased plant height and moisture content, while solid content decreased (p < 0.05). The acetonic and ethanolic extracts exhibited more intense odor and darker coloration than the aqueous extracts. The sprouting duration and extraction solvent significantly influenced extract yield, total phenolic content, and antioxidant activity (p<0.05). The aqueous and ethanolic extracts showed higher phenolic content and antioxidant activity than the acetic extract. The highest total phenolic content (50.32 ± 4.13 mg GAE/g extract) was observed in 5-day-old sprouts extracted with ethanol. The highest total flavonoid contents were found in the ethanolic extracts of 7- and 9-day-old sprouts (96.01 ± 3.91 and 95.60 ± 1.22 mg QE/g extract, respectively). For antioxidant activity, the highest DPPH scavenging capacity was observed in 5-day-old sprouts extracted with ethanol (31.79 mg TEAC/g extract), followed by 7-day-old
sprouts extracted with water (26.44 mg Trolox equivalent/g extract). The aqueous extracts demonstrated consistently high FRAP activity in sprouts aged 39 days, while the highest FRAP value was found in 5-day-old sprouts extracted with ethanol (102.72 ± 1.64 mg TEAC/g extract). A strong positive correlation was found between total phenolic content and antioxidant activity (r=0.860 for DPPH; r=0.856 for FRAP). Further studies of bioactive constituents and other biological activities are recommended to support the applications of radish microgreen extracts in cosmetics.