ESR spectroscopic studies on free radical quenching action of finger millet (Eleusine coracana)

The free radical quenching action of finger millet (Eleusine coracana) on 1,1'diphenyl-2-picrylhydrazyl (5.407 x 1017 spins/ml-1) and hydroxyl (0.6015 x 1015 spins/ml-1) radicals was studied by electron spin resonance (ESR) spectrometry. A 10 ml concentrate of the methanol extract was prepared using 25 g of the cereal grains and all analysis done after 1:10 dilution. DPPH radical quenching with 50 μl of the extracts showed that the brown finger millet quenched 94% whereas the white finger millet quenched only 4%. The phenolic content of brown finger millet was 96% higher than the white variety. Processing of the brown finger millet by germination and/or fermentation decreased the quenching activity. In comparison, foxtail millet, pearl millet and sorghum, quenched 91, 59 and 52 percent respectively, while wheat, rice (dehusked) and rice husk quenched 18, 1.8 and 20% respectively. Brown finger millet (50 μl) also quenched 77% of hydroxyl radicals. The results indicate that finger millet is a potent source of antioxidant compounds.