First evidence of C- and O-glycosyl flavone in blood orange (Citrus sinensis (L.) Osbeck) juice and their influence on antioxidant properties.

RP-LC-DAD-ESI-MS-MS separation/identification protocol has been employed for the identification and characterisation of nine C- and O-glycosyl flavonoids in Moro (Citrus sinensis (L.) Osbeck) juice grown in Southern Italy. For the first time we reported the presence of five C-glycosyl flavones (lucenin-2, vicenin-2, stellarin-2, lucenin-2 4'-methyl ether and scoparin), a 3-hydroxy-3-methylglutaryl glycosyl flavonol (3-hydroxy-3-methylglutaryl glycosyl quercetin) and a flavone O-glycosides (chrysoeriol 7-O-neoesperidoside). Moreover, the influence of the identified C- and O-glycosyl flavonoids on the total antioxidant activity of crude juice has been evaluated on the basis of its ability to scavenge DPPH•, OH• and ABTS•+ radicals and to reduce iron.