2.3.2. Total Flavonoid Content

The TFC of the HI extracts was assessed according to a method previously described [17]. In a 96-well plate, 100 μL of sample extract was added to 100 μL of 2% AlCl3 aqueous solution. The plate was incubated in the dark at room temperature for 15 min and the absorbance was measured at 420 nm against a solvent blank. The TFC was expressed as quercetin equivalents (QE) per dw of involucre (mg QE/g dw).
