Abstract
Scientists intensely search for new sources of antioxidants, perceived as important health-promoting agents. Some species of the large genus Centaurea provide raw materials for the pharmaceutical and cosmetic industries, as well as produce edible flowers. This is the first study that determines the content of total polyphenols, flavonoids, reducing sugars, free amino acids and the antioxidant potential in the flower extracts of C. nigra L., C. orientalis L. and C. phrygia L. The total polyphenol and flavonoid content is the highest in the extract of C. orientalis, and the lowest in that of C. phrygia. Similarly, C. orientalis shows the greatest scavenging activity on DPPH (1,1-diphenyl-2-picryl-hydrazyl), ABTS [2,2′-azobis(3-ethylbenzothiazoline-6-sulfonate)] and Fe3+ reducing power assays, whereas the lowest activity is found for C. phrygia. The highest content of reducing sugars is found in C. nigra, while C. orientalis has the highest levels of free amino acids. We find a strong positive correlation between total phenolics and flavonoids and the antioxidant capacity of all three Centaurea species. Moreover, the content of free amino acids strongly and positively correlates with the levels of total phenolics and flavonoids, antioxidant activity assessed by DPPH and ABTS assays and Fe3+ reducing power. Summing up, C. orientalis exhibits the strongest antioxidant potential of the investigated Centaurea species. This species could potentially be a natural source of antioxidant substances for the pharmacy, cosmetics and food industries. The content of free amino acids may be used as a marker of the antioxidant status of Centaurea species.
Highlights
Free radicals and antioxidants are natural components of the body, and are essential for the proper course of many metabolic processes
The aim of this work is to compare the total content of polyphenols and flavonoids as well as the antioxidant activity of flower extracts from C. nigra, C. orientalis and C. phrygia
Polyphenols are secondary plant metabolites with antioxidant properties resulting from the presence of the –OH group, scavenge free radicals [24]
Summary
Free radicals and antioxidants are natural components of the body, and are essential for the proper course of many metabolic processes. Excessive amounts of synthetic antioxidants used as food preservatives, such as butyl derivatives of hydroxyanisole and hydroxytoluene and tertiary butylhydroquinone, do not reduce harmful effects of free radicals, but often contribute to their formation and greater activity, which may result in the initiation of diseases [5,6]. For these reasons, many studies focus on finding non-toxic, natural sources of antioxidants [7]. The most important compounds include polyphenols that can inhibit or delay oxidation processes in both living organisms and food [8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
