Chemical features and bioactivities of cornflower (Centaurea cyanus L.) capitula: The blue flowers and the unexplored non-edible part.

Highlights • The flowers and non-edible lower part of the cornflower capitula were characterized. • Flowers were richer in tocopherols, organic acids, and apigenin and cyanidin derivatives. • The lower part had high syringic acid levels and better cell-based antioxidant activity. • Hydromethanolic extracts had antibacterial activity and no cytotoxicity on PLP2 cells. • Cornflower capitulum-based colorants and functional ingredients can be exploited. Abstract Cornflower is a flowering weed and ornamental plant whose blue flowers have been used for food, decorative and colouring purposes. In this study, the upper (edible flowers) and lower (non-edible receptacle and involucre) parts of the capitulum were studied and compared for their chemical composition and bioactive properties. The flowers were richer in tocopherols, organic acids, and apigenin derivatives (mainly apigenin-7- O -glucuronide-4′- O -(6- O -malonylglucoside)) than the non-edible bristly part (where syringic acid predominated). Four cyanidin derivatives were identified in the flowers. The extract of the non-edible part was more efficient in inhibiting the formation of thiobarbituric acid reactive substances (TBARS), the bleaching of β-carotene, and the haemolysis of the erythrocytes membrane. In general, the extracts were more active against Gram-positive bacteria and had no cytotoxicity against non-tumour liver PLP2 cells. Therefore, while flowers are a potential source of natural cyanidin-based colorants, the lower part of the capitulum has bioactive properties to be exploited in different food or pharmaceutical formulations. [ABSTRACT FROM AUTHOR]