Laboratory analysisBoth the antioxidant activity and the total content of antho-cyanins were expressed on a fresh weight (FW) basis. Flowersamples (1 g) were extracted with 10 mL methanol 80% (v/v), con-taining 1% of HCl, for 12 h at 4◦C.Antioxidant activity was determined on the extracts by the FRAP(ferric ion reducing antioxidant power) assay following Pellegriniet al. (2003). A calibration curve was prepared with increasing con-centrations of FeSO4(reagent grade, Sigma–Aldrich), and resultswere expressed as mmol FeSO4100 g−1FW