Identification of flavonoids and hydroxycinnamic acids in pak choi varieties (Brassica campestris L. ssp. chinensis var. communis) by HPLC-ESI-MSn and NMR and their quantification by HPLC-DAD.
Twenty-eight polyphenols (11 flavonoid derivatives and 17 hydroxycinnamic acid derivatives) were detected in different cultivars of the Chinese cabbage pak choi ( Brassica campestris L. ssp. chinensis var. communis) by HPLC-DAD-ESI-MS(n). Kaempferol was found to be the major flavonoid in pak choi, glycosylated and acylated with different compounds. Smaller amounts of isorhamnetin were also detected. A structural determination was carried out by (1)H and (13)C NMR spectroscopy for the main compound, kaempferol-3-O-hydroxyferuloylsophoroside-7-O-glucoside, for the first time. Hydroxycinnamic acid derivatives were identified as different esters of quinic acid, glycosides, and malic acid. The latter ones are described for the first time in cabbages. The content of polyphenols was determined in 11 cultivars of pak choi, with higher concentrations present in the leaf blade than in the leaf stem. Hydroxycinnamic acid esters, particularly malic acid derivatives, are present in both the leaf blade and leaf stem, whereas flavonoid levels were determined only in the leaf blade.
Harbaum
Britta
B
Department of Food Technology, Institute of Human Nutrition and Food Science, University of Kiel, Heinrich-Hecht-Platz 10, 24118 Kiel, Germany. info@foodtech.uni-kiel.de
Hubbermann
Eva Maria
EM
Wolff
Christian
C
Herges
Rainer
R
Zhu
Zhujun
Z
Schwarz
Karin
K
D001937:Brassica / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000032:analysis* / Q000737:chemistry; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols / Q000032:analysis; D059808:Polyphenols; D021241:Spectrometry, Mass, Electrospray Ionization
D003373:Coumaric Acids; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols