For quantification of resveratrol, freeze-dried samples (5 g)
were suspended in 60 ml of extraction solution (ethanol:water at
1:1 ratio) and heated for 30 min at 70 ?C under constant stirring.
Following, extracts were filtered (Whatman No. 1) and concentrated under vacuum at 70 ?C using a rotoevaporator (Buchi R-210 Rotavapor, Buchi Co., New Castel, DE). The concentrate was resuspended in 5 ml methanol and analysed by HPLC.