Phenolic Content and Antioxidant Activity of the Croatian Red Clover Germplasm Collection

Abstract

The leaf samples of two varieties, twenty breeding populations, and seven local populations of the Croatian red clover were collected in the full flowering stage, with an aim to evaluate their phenolic content and antioxidant activity by using the spectrophotometric methods. A significant variation among the varieties/populations in the content of total phenolics and flavonoids was determined. The results demonstrated that the red clover is a rich source of phenolics and flavonoids, ranging from 38.67 to 59.96 mg GAE/g of DM and 21.19 to 51.48 mg CE/g of DM, respectively. The high levels in both phenolics and flavonoids were found in breeding populations/variety CD-8, Rc-11/7, Rc-11/8, Rc-11/15 and OS Osiris. The leaf extracts manifested a strong antioxidant activity towards diphenyl-1-picrylhydrazyl (DPPH), with a variation from 31.50 to 63.14%. A significant correlation was found between the antioxidant activity of the extracts and their total phenolic and flavonoid content (r = 0.737 and 0.839, respectively). Considering the obtained results, the crude extracts of red clover manifested a significant antioxidant potential and can be used as a natural source of biologically active components in the human and animal nutrition.

The Effect of Traditional and Cyclodextrin-Assisted Extraction Methods on Trifolium pratense L. (Red Clover) Extracts Antioxidant Potential

“…Furthermore, all the methods presented a significant correlation between them, with high values in the Spearman correlation coefficient. Numerous studies have also reported this correlation [ 43 , 55 ].…”

“…However, the presence of phenolic compounds and their distribution in the red clover vary due to many factors—origin, cultivation influences, weather conditions, plant parts, growing stages, harvesting season, etc. [ 55 ]. Therefore, it would not be entirely appropriate to compare the results of different studies.…”

Impact of Polyvinylpyrrolidone-Vinyl Acetate Copolymer and Sodium Starch Glycolate Excipients on Phenolic Extraction from Red Clover: Enhancing Biological Activity and Antioxidant Potential

“…The determined antioxidant activity (DPPH) of the red clover extract was lower compared with the results in this study by approximately 30% (controls) and 33–39% compared with samples prepared using the excipients. In other research by Horvat et al, extracts were prepared from red clover leaves of different breeding populations [ 45 ]. The results showed that on average, DPPH inhibition was 18% lower compared to our controls and 24–27% lower compared with the samples prepared using the excipients.…”

Application of Antiviral, Antioxidant and Antibacterial Glycyrrhiza glabra L., Trifolium pratense L. Extracts and Myristica fragrans Houtt. Essential Oil in Microcapsules

“…Studies in the literature have shown that both Trifolium pratense L. and Glycyrrhiza glabra L. are good antioxidants. Trifolium pratense L. is known to contain isoflavones (daidzein, genistein, formononetin, and biochanin A), which possess estrogenic effects, but antioxidant properties of extract can be related to quercetin, hyperoside, clovamides, and other phenolic compounds [ 52 ]. The reported main phenolic compounds in Glycyrrhiza glabra L. extract responsible for its antioxidant activity are also isoflavones, such as glabridin, hispaglabridin A, and 30-hydroxy-4-O-methylglabridin [ 53 ].…”