Dried cardoon leaf sample (100 mg) was extracted sequentially three times in 10, 5, and 5 mL of fresh ethanol/water (80:20 v/v) containing 1 mL L-1 of 370 g L-1 HCl (total volume 25 mL). The extraction mixture was stirred for 10 min and then solids were removed by centrifugation at 503 × g for 5 min. The total content of phenolic compounds in each extract was determined by the Folin–Ciocalteu method (Singleton and Rossi, 1965 ). A calibration curve was prepared using aliquots of gallic acid ethanolic solutions, and results were expressed as gallic acid equivalents (mg gallic acid g-1 dry weight). All reagents and solvents used to prepare standard solutions and to extract phenols were of analytical grade and were purchased from Sigma Aldrich (Milan, Italy).
Total flavonoids were determined following the colorimetric aluminum chloride method reported by Dutta and Maharia (2012) (link). A calibration curve was prepared using aliquots of quercitin (Sigma Aldrich, Milan, Italy), and results were expressed as quercetin equivalents (mg quercetin g-1 dry weight).
Total flavonoids were determined following the colorimetric aluminum chloride method reported by Dutta and Maharia (2012) (link). A calibration curve was prepared using aliquots of quercitin (Sigma Aldrich, Milan, Italy), and results were expressed as quercetin equivalents (mg quercetin g-1 dry weight).