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

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.

Wild and Cultivated Centaurea raphanina subsp. mixta: A Valuable Source of Bioactive Compounds

“…The antioxidant activity was evaluated by applying two cell-based assays in the already prepared hydroethanolic extracts (see Section 2.2): the oxidative haemolysis (OxHLIA) and the thiobarbituric acid reactive substances (TBARS) formation inhibition assays previously described by Lockowandt et al [42], using the above prepared hydroethanolic extracts. The used positive control was Trolox.…”

“…The antihaemolytic activity was evaluated by the oxidative haemolysis inhibition assay (OxHLIA) [42]. The results were presented as IC 50 values, which is the extract concentration (µg/mL) required to inhibit oxidative haemolysis of 50% of the erythrocytes for ∆t of 60 min.…”

Cotton and cardoon byproducts as potential growing media components for Cichorium spinosum L. commercial cultivation

“…The TBARS assay was performed following a methodology described by Barreira et al (2013) and results were expressed in IC 50 values, which represent sample concentration providing 50% of antioxidant activity. The anti-haemolytic activity of the extracts was evaluated by the oxidative haemolysis inhibition assay (OxHLIA), as previously described by Lockowandt et al (2019). The results were presented as IC 50 values, which represent extract concentration that delayed the haemolysis time for 60 min, with 50% of intact erythrocytes.…”

Screening of Antioxidant Potentials and Bioactive Properties of the Extracts Obtained from Two Centaurea L. Species (C. kroumirensis Coss. and C. sicula L. subsp sicula)

“…Interestingly, the hexanic extract of C. kroumirensis, which showed the highest antioxidant ability (IC 50 = 0.49 ± 0.01 mg/mL), does not exhibit the most important TPC. The noteworthy differences could be explained by the synergistic effect of polyphenols extracted in hexanic sample and other non-phenolic antioxidants present in Centaurea plant (e.g., vitamin C [35], carotenoids and tocopherols [36], sesquiterpene lactones [37]), which significantly contribute to the free radical scavenging activity [20,38]. The chloroform extract has similar IC 50 to methanol and ethanol extract of C. kroumirensis and C. sicula, respectively.…”