title: Characterization of flavonol conjugates in immature leaves of pak choi [Brassica rapa L. Ssp. chinensis L. (Hanelt.)] by HPLC-DAD and LC-MS/MS.
abstract: The flavonoid composition of immature leaves of pak choi [Brassica rapa L. ssp. chinensis L. (Hanelt.)] was investigated. Flavonol aglycone content was measured in 11 pak choi varieties, indicating significant differences (P < 0.05) in content between varieties and relatively high contents of kaempferol and isorhamnetin. Levels of quercetin ranged from 3.2 to 6.1 mg/100 g of dry weight (DW), whereas levels of isorhamnetin and kaempferol were significantly higher (8.1-35.1 and 36.0-102.6 mg/100 g of DW, respectively). A large number of glycoside and hydroxycinnamic acid derivatives of quercetin, kaempferol, and isorhamnetin were identified in cv. 'Shanghai' by LC/UV-DAD/ESI-MS/MS. The UV-DAD data allowed identification of hydroxycinnamic acid derivatives, but detailed MS/MS fragmentations were required for the structure elucidation. Pak choi could be a potentially important source of dietary flavonols, in particular, kaempferol and isorhamnetin.
authors.affiliation: Department of Primary Industries, Primary Industries Research Victoria, Werribee Centre, 621 Sneydes Road, Werribee 3030, Victoria, Australia. simone.rochfort@dpi.vic.gov.au
authors.forename: Simone J
authors.initials: SJ
authors.lastname: Rochfort
authors.forename: Michael
authors.initials: M
authors.lastname: Imsic
authors.forename: Rod
authors.initials: R
authors.lastname: Jones
authors.forename: V Craige
authors.initials: VC
authors.lastname: Trenerry
authors.forename: Bruce
authors.initials: B
authors.lastname: Tomkins
mesh_terms: D029741:Brassica rapa / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000032:analysis; D044948:Flavonols / Q000032:analysis*; D006027:Glycosides / Q000032:analysis; D044949:Kaempferols / Q000032:analysis; D013058:Mass Spectrometry; D018515:Plant Leaves / Q000737:chemistry*; D011794:Quercetin / Q000032:analysis / Q000031:analogs & derivatives
chemical_list: D003373:Coumaric Acids; D044948:Flavonols; D006027:Glycosides; D044949:Kaempferols; C047368:3-methylquercetin; C006552:kaempferol; D011794:Quercetin