Antioxidant Potential of Flower Extracts from Centaurea spp. Depends on Their Content of Phenolics, Flavonoids and Free Amino Acids

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.

Some Antioxidant Properties of Components from the Flower of Ochna integerrima and Their Beneficial Effects on HaCaT Keratinocytes and in Silico Analysis on Tyrosinase

“…The low values of IC50‐DPPH assay are associated with the high value of TPC and TFC contents indicating negative correlations. The positive correlations was explained by the high levels of TPC and TFC [21,22] . In our study, the strong Pearson's correlation c oefficient (r>0.7) showed that phenolic and flavonoid secondary metabolites are the major contribution to the antioxidant activity by DPPH method which are consistent with previous data [21] .…”

“…[21,22] In our study, the strong Pearson's correlation coefficient (r > 0.7) showed that phenolic and flavonoid secondary metabolites are the major contribution to the antioxidant activity by DPPH method which are consistent with previous data. [21] Moreover, the number and position of hydroxy groups in phenolic compounds determine antioxidant activity, whereas the presence of glycoside moieties attenuates antioxidant activity. [23,24] In particular, the 3',4'-dihydroxy groups of the B-ring dominate their antioxidant activity.…”

Antioxidant and enzyme inhibitory properties of sacha inchi ( Plukenetia volubilis ) protein hydrolysate and its peptide fractions

“…In this study, only their total amino acid content was examined; however, interference from short‐chain polysaccharides and free amino acids is a possibility. According to Salachna, Pietrak, and Lopusiewicz (2021), reducing sugars and free amino acids possess antioxidant properties. Lacroix, Chen, Kitts, and Li‐Chan (2017) revealed that free amino acids, including Tyr, Leu, Pro, and Gln, exhibited modest ACE inhibition, etc.…”

“…According to Salachna, Pietrak, and Lopusiewicz (2021), reducing sugars and free amino acids possess antioxidant properties. phytochemicals, but it uses a lesser amount for peptides from plant proteins (Alashi et al, 2014b).…”

Cardioprotective Effect of Centaurea castriferrei Borbás & Waisb Extract against Doxorubicin-Induced Cardiotoxicity in H9c2 Cells

“…Over the past several years, there has been growing interest in the plants of the genus Centaurea L. (Asteraceae), which is a genus with several hundred representatives and that is native to the Mediterranean basin but is practically widespread on most continents [ 17 , 18 ]. The plants are quite expansive and do not require special soil conditions [ 19 , 20 , 21 ].…”