Antioxidant activity of ginger extract and identification of its active components

The object of presented study was the evaluation of antioxidant activity of extract from Zingiber officinale. A method for the preparation of the extract was chosen, which enabled to isolate mostly phenolic compounds. According to the measurements with Folin-Ciocalteu reagent, obtained extract comprised total polyphenols (181.41 mg_GAE/g of extract) from which flavonoids contributed to 7.8 % (14.15 mg_quercetin/g of extract). Nuclear magnetic resonance (NMR) analysis showed that the phenolic ketones were predominant in the extracts of whole phenolic compounds. According to results of two spectrophotometric methods (ABTS and DPPH test), ginger extract showed stronger ability to scavenge DPPH radical than ABTS cation radical.