Characterization and quantification of flavonoids and hydroxycinnamic acids in curly kale (Brassica oleracea L. convar. acephala var. sabellica) by HPLC-DAD-ESI-MSn.

Kale is a leafy green vegetable belonging to the Brassicaceae family, a group of vegetables including cabbage, broccoli, cauliflower, and Brussels sprouts, with a high content of health-promoting phytochemicals. The flavonoids and hydroxycinammic acids of curly kale (Brassica oleracea L. ssp. oleracea convar. acephala (DC.) Alef. var. sabellica L.), a variety of kale, were characterized and identified primarily through HPLC-DAD-ESI-MSn analysis. Thirty-two phenolic compounds including glycosides of quercetin and kaempferol and derivatives of p-coumaric, ferulic, sinapic, and caffeic acid were tentatively identified, providing a more complete identification of phenolic compounds in curly kale than previously reported. Moreover, three hydroxycinnamic acids and one flavonoid with an unusual high grade of glycosylation, quercetin-3-disinapoyl-triglucoside-7-diglucoside, have been tentatively identified for the first time. The influence of different extraction conditions (extraction method, solvent type, solve...