Abstract
Coleostephus myconis (L.) Rchb.f. (Asteraceae) is a species with ruderal growth and persistence in abandoned soils, being characterized for its plentiful yellow flowering between March and August. Despite its botanical relevance, C. myconis had never been studied neither for its antioxidant activity, nor individual phenolic compounds. Herein, the antioxidant activity of different botanical parts: stems and leaves (green parts), floral buds, flowers in anthesis and senescent flowers, was studied in selected extracts (ethanol, ethanol:water 1:1 and water) through different chemical and biochemical assays. In addition, the phenolic profiles of the hydroethanolic extracts of each botanical part were also characterized by liquid chromatography with diode array detection and electrospray ionization tandem mass spectrometry (LC-DAD-ESI/MSn). The antioxidant activity was significantly modulated by the extract type, with the hydroethanolic extracts showing the highest antioxidant activity, especially those obtained from the senescent flowers and floral buds. The phenolic profiles were the same for all flowering stages (with quantitative differences), but that characterized in the green parts were quite different. Floral buds gave the highest contents in phenolic compounds, mainly due to the contribution of 3,5-O-dicaffeoylquinic acid and myricetin-O-methyl-hexoside. Overall, C. myconis showed an interesting potential to be included in different industrial applications.
Highlights
Some researchers suggest that two-thirds of the world’s plant species have medicinal value
Antioxidant activity of the C. myconis extracts The solvent type had some influence on the antioxidant potential, as it was exemplified by the higher activity measured in the hydroethanolic extracts, when compared to the remaining assayed extraction solvents (Table 1)
Floral buds and senescent flowers gave the highest levels of antioxidant activity, with the best results obtained for the hydroethanolic extracts from senescent flowers (DPPH scavenging activity: 0.25 mg/mL; reducing power: 0.13 mg/mL; β-carotene bleaching inhibition: 0.41 mg/mL; thiobarbituric acid reactive substances (TBARS) formation inhibition: 0.08 mg/mL, in the latter with similar values to those obtained with the other flowering stages)
Summary
Some researchers suggest that two-thirds of the world’s plant species have medicinal value. Some of the biological properties of plant-derived products are related to their antioxidant activity. The antioxidant activity of plants is often related to its individual phenolic compounds. These compounds occur frequently conjugated with glycosides, being usually located in the cell vacuolar structures. As far as we know, C. myconis species was not previoulsy studied for its antioxidant activity and individual phenolic compounds, since no related references could be found in literature. Besides the innovative character, studying C. myconis is relevant for its high dissemination in the Portuguese territory (mainly in the northern region)
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