Elucidation of the flavonoid and furocoumarin composition and radical-scavenging activity of green and ripe chinotto (Citrus myrtifolia Raf.) fruit tissues, leaves and seeds

Citrus myrtifolia Raf. (chinotto) flavedo, albedo and carpel membranes from green and ripe fruits, as well as seeds and leaves, were investigated for the first time for their flavonoid and furocoumarin composition. Twenty-three unique compounds distributed in the different fruit/plant parts were identified and quantified. All samples analysed contained flavanone O-glycosides, flavone C- and O-glycosides and furocoumarins; flavedos and albedos also contained significant amounts of polymethoxyflavones. Flavedo and albedo extracts were found to be richest in flavonoids and furocoumarins, containing up to 1.95 g/kg fresh weight. Flavedo, albedo and carpel membranes from ripe fruits were found to be richer than the corresponding tissues from unripe fruits. The remarkable radical-scavenging activity of all the extracts was tested by DPPH•, ABTS•+ and FRAP methods, revealing that (i) they were particularly efficient in quenching ABTS•+ radical cations (up to 9.8 mM Trolox equivalents), and (ii) flavedo and albedo extracts, on average, showed the highest antioxidant capacity.