Highly glycosylated flavonols with an O-linked branched pentasaccharide from Iberis saxatilis (Brassicaceae)

► Four isorhamnetin glycoside structures determined using cryoprobe NMR and MS. ► First flavonol glycosides to be described with an O-linked pentasaccharide chain. ► Kaempferol and quercetin pentaglycosides detected as minor components by LC-MS/MS. ► Sinapoylation of glucosyl residues typical of Brassicaceae chemistry.