Flavonoid content of commercial capers ( Capparis spinosa, C. sicula and C. orientalis ) produced in mediterranean countries

Abstract

The flavonol content of commercial capers (pickled flower buds of Capparis spinosa L., C. sicula Veill. in Duham. and C. orientalis Veill. in Duham.) produced in different Mediterranean countries (Spain, Italy, Greece, Turkey and Morocco) has been analysed. The content of quercetin 3-rutinoside, kaempferol 3-rutinoside; and kaempferol 3-rhamnosyl-rutinoside as well as the aglycones (quercetin and kaempferol) were evaluated by HPLC coupled with a diode-array detector. The free aglycones were not detected in the original flower buds, indicating that they were produced during the brining process. In addition, brining extracted most of the kaempferol 3-rhamnosyl rutinoside present in the original buds, this being a minor constituent in pickled capers. The average content of flavonoid glycosides in commercial capers was 5.18 mg/g fresh weight. When this value is converted to the corresponding aglycones (quercetin and kaempferol), capers provide an average of 3.86 mg/g fresh weight. A serving of capers (10 g) will provide 65 mg of flavonoid glycosides or the equivalent 40 mg of quercetin as aglycone.