Journal of Chromatography A, 1054 (2004) 181–193 Characterisation of flavonols in broccoli (Brassica oleracea L. var. italica) by liquid chromatography–UV diode-array detection–electrospray ionisation mass spectrometry F. Vallejo, F.A. Tomás-Barberán, F. Ferreres ∗ Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS-CSIC, P.O. BOX 164, E-30100 Espinardo, Murcia, Spain Available online 28 July 2004 Abstract The flavonoid composition of broccoli inflorescences has been studied by LC/UV-DAD/ESI-MS n . A large number of hydroxycinnamic acid esters of kaempferol and quercetin glucosides has been characterised. The structures of the flavonoid glycosides were analysed after alkaline hydrolysis, and were identified as 3-sophoroside/sophorotrioside-7-glucoside/sophoroside of kaempferol, quercetin and isorhamnetin (this last found in trace amount). These complex quercetin and isorhamnetin glucosides have not been previously characterised in nature. In addition, several less complex glucosides based on the same aglycones have been identified. The effect of sugar substitution and acylation on chromatographic mobility and ESI ionisation and fragmentation are discussed. © 2004 Elsevier B.V. All rights reserved. Keywords: Food analysis; Broccoli; Flavonoids; Acylated glycosides 1. Introduction Recent studies have shown the relevant biological activ- ities of flavonoids against various types of cancer and car- diovascular diseases [1–3]. Broccoli inflorescence is a good source of health promoting compounds since it contains glu- cosinolates, flavonoids and hydroxycinnamic acids, vitamin C and other minor compounds. Scarce information is available regarding broccoli polyphenols identification. Several studies have previously reported on broccoli flavonoids but none has described more than five flavonol glycosides and also without iden- tifying the combinations with hydroxycinnamic acids and with glycosylations up to two glucoses [5,6]. A recent study on cauliflower flavonoids showed that Brassicaceae species contain very complex flavonoids with up to five sugar residues on the flavonol nucleus [7]. Although broccoli has ∗ Corresponding author. Tel.: +34 9683 963 24; fax: +34 9683 962 13. E-mail address: federico@cebas.csic.es (F. Ferreres). been reported to be one of the main flavonol sources in the diet, very little is known about the structures, as they are combination of hydroxycinnamic acids with highly glycosy- lated flavonoids, that make their identification very difficult by classical methods [4]. HPLC coupled to MS–MS–DAD has shown to be a very useful method in the identification of these complex flavonoids, as have been recently reported in cauliflower leaves [7]. The purpose of this work was to identify the polyphenols from broccoli inflorescences by high-performance liquid chromatogram coupled with on-line mass spectrometry with electrospray ionisation source (LC/UV-DAD/ESI-MS n ). 2. Experimental 2.1. Plant material The broccoli (Brassica oleracea L. var. italica) (Marathon cv.) florets used for the assays were obtained from the In- stituto Murciano de Investigacion y Desarrollo Agraroali- mentario (IMIDA, Murcia, Spain). At optimum commercial 0021-9673/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2004.05.045