Comprehensive Qualitative and Quantitative Analysis of Flavonoids in Dandelion (Taraxacum officinale) Flowers and Food Products

Taraxacum officinale, a cosmopolitan perennial, is widely used as an edible, fodder, honey, and medicinal plant. Interestingly, detailed LC-QTOF-MS profiling of the flower extract revealed the presence of several flavonoid signals, most likely lacking literature confirmation. Targeted isolation, including extraction based on DoE planning, led to the isolation of 11 flavonoids, three of which were new (16, 18, and 33). Their structures were determined by the NMR technique. Both biflavones (16 and 18) were structured by two luteolin molecules, linked by a C–C bond through IB (C-6′) and IIA (C-6″ or C-8″) rings. Novel flavonolignan (33) was composed of tricin and an unusual carboxyl function containing a lignan moiety. The content of 28 flavonoids (glycosides, aglycones, biflavones, and flavonolignans) was determined by the LC–MS/MS method in raw flowers and dandelion syrups and tincture. Multivariate analyses showed the separation of spring and autumn flowers and a high diversity of food products and helped to identify metabolites correlated with the samples.