Extraction was performed according to the method of Yang et al. (2002) with some modifications. Five grams of each powdered sample was extracted with 100 ml of ethanol. The mixture was placed in a conical flask (wrapped with an aluminium foil) and agitated at 200 rpm with orbital shaker for 1 hour at 25°C. The extract was then separated from the residue by filtration through Whatman No. 1 filter paper. The remaining residue was re-extracted twice, and then the two extracts were combined. The residual solvent of ethanol extracts was removed under reduced pressure at 40°C using a rotary evaporator to dryness. For aqueous extraction, the aqueous extract was lyophilized using a freeze dryer. Both of the dried extract was used directly for all analysis.