Effect of foliar application of selenium on the antioxidant activity of aqueous and ethanolic extracts of selenium-enriched rice
Xu, J.; Hu, Q.
Journal of Agricultural and Food Chemistry 52(6): 1759-1763
Selenium fertilizer was foliar applied to determine the effects of antioxidant activity of seleniumenriched rice assessed by a,α-diphenyl-P-picylhydrazyl (DPPH) radical scavenging and the ferric thiocyanate (FTC) method. Results showed that selenium concentration in rice was significantly enhanced dose dependently. Aqueous or ethanolic extracts of rice displayed significantly higher antioxidant activity against lipid peroxidation. The activities of aqueous extracts were significantly higher than those of ethanolic extracts and increased with the increasing selenium concentration in rice. The DPPH assay showed that the kinetic behaviors of aqueous extracts were complex and slow, while ethanolic extracts reacted quickly with DPPH radical. Aqueous extracts of rice exhibited higher antiradical efficiencies than ethanolic extracts, and rice (1.275 mg Se kg-1) presented the lowest EC50 values of 533.46±0.58,tig mL-1. As compared to rice extracts, all of the reference antioxidants showed more than 4-fold antiradical efficiencies than rice extracts. This radical scavenging activity was significantly correlated with selenium concentrations in rice (R=0.862, p<0.05), while ethanolic extracts were inversely correlated with selenium concentration in rice.