Ulex europaeus: from noxious weed to source of valuable isoflavones and flavanones

• The phytochemical profile of Ulex europaeus (leaves and flowers) is studied.
• About 130 compounds were detected by HPLC-ESI–MSn.
• The most abundant compounds were glycosylated flavonoids.
• Ulex flowers can be considered a new source of liquiritigenin derivatives.
• Ulex showed good ability to scavenge free radicals and inhibit digestive enzymes.

The screening and quantification of the main phenolic compounds in leaves and flowers of Ulex europaeus (gorse) was carried out by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI–MSn) after ultrasound-assisted extraction with methanol. About 98% of compounds corresponded to flavonoids, distributed as flavonols, flavones, isoflavones and flavanones. Flavonols were mainly quercetin glucosides; most of the found flavones were apigenin derivatives and the isoflavone group was dominated by glycitin. The flavanone group was composed mainly of liquiritigenin derivatives, substances usually found in liquorice (Glycyrrhiza ssp) and associated with high pharmacological relevance; in Ulex they represent about 25% of total polyphenols content. Phenolic acids and saponins were also detected, as minor components. In vitro antioxidant activity (nitric oxide, superoxide assays, ABTS and DPPH assays) of leaves and flowers, and their inhibitory effects towards digestive enzymes related to carbohydrate metabolism (α-glucosidase and α-amylase) were also studied.