Antioxidant activity of tropical ginger extracts and analysis of the contained curcuminoids

Antioxidant activities of the rhizomes of nine tropical gingers (Curcuma aeruginosa, Curcuma domestica, Curcuma heyneana, Curcuma mangga, Curcuma xanthorrhiza, Zingiber cassumunar, Phaeomeria speciosa, Alpinia galanga, and Amomum kepulaga) have been measured by thiocyanate and TBA methods in a water/alcohol system after extraction and fractionation with organic solvents. The quantity of three known curcuminoids, one of the potent antioxidant family of ginger species, in the extracts has been analyzed by HPLC. The antioxidant activity of the extracts of the gingers was greater than that estimated from the actual quantity of three known curcuminoids in the extracts.