Biological activity of clovers – Free radical scavenging ability and antioxidant action of sixTrifoliumspecies

Abstract

Context: Clovers were chosen on the basis of traditional medicine recommendations, agricultural value, or available information on their promising chemical profiles.Objective: This study evaluates and compares free radical scavenging and antioxidant properties of six clover species: Trifolium alexandrinum L. (Leguminosae), Trifolium fragiferum L., Trifolium hybridum L., Trifolium incarnatum L., Trifolium resupinatum var. majus Boiss., and Trifolium resupinatum var. resupinatum L. Materials and methods: Free radical scavenging activity of the extracts (1.5-50 mg/ml) was estimated by reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH ) and 2,2 0 -azino-bis(3-ethylbenzthiazoline-6-sulphonic) acid (ABTS ) radicals. The Trifolium extract effects on total antioxidant capacity of blood plasma were determined by the reduction of ABTS + and DPPH radicals, as well as with the use of the ferric reducing ability of plasma (FRAP) assay. Results: The UPLC analysis of chemical profiles of the examined extracts showed the presence of three or four groups of phenolic substances, including phenolic acids, clovamides, isoflavones, and other flavonoids. The measurements of free radical scavenging and ferric reducing ability of the examined clover extracts revealed the strongest effect for T. alexandrinum. Furthermore, antioxidant activity assays in human plasma have shown protective effects of all extracts against peroxynitrite-induced reduction of total antioxidant capacity. Conclusions: Trifolium plants may be a rich source of bioactive substances with antioxidant properties. The examined extracts displayed free radical scavenging action and partly protected blood plasma against peroxynitrite-induced oxidative stress; however, the beneficial effects of T. alexandrinum and T. incarnatum seem to be slightly higher.

Free radical scavenging actions of threeTrifoliumspecies in the protection of blood plasma antioxidant capacityin vitro

“…Similarly, the ferric reducing abilities of the phenolic fraction of T. pratense and T. pallidum extract were considerably higher than those for T. pratense crude extract and phenolic fraction of T. scabrum (Table 3). Additionally, the EC 50 values obtained for T. pratense, T. pallidum, and T. scabrum from measurements of free radical scavenging tests during this study were compared with results for other six clover species, derived from our earlier experiments (Kolodziejczyk-Czepas et al, 2014). Our comparative analysis of the radical scavenging properties of 10 extracts from Trifolium species indicated that five of them (T. alexandrinum, T. pallidum, T. pratense (phenolic fraction), T. resupinatim var.…”

“…Determination of the TAC of plasma using the FRAP assay was carried out according to modified method of Benzie and Strain (1996) as was described previously (Kolodziejczyk-Czepas et al, 2014). This method was also used for the evaluation of ferric reducing ability of different concentrations of the tested Trifolium extracts, where instead of blood plasma, solutions of these extracts were used.…”

Trifoliumspecies – the latest findings on chemical profile, ethnomedicinal use and pharmacological properties

“…A comparative in‐vitro analysis of free radical scavenging properties of extracts from other Trifolium species demonstrated that several clovers might be a source of potent antioxidants. On the other hand, the mentioned works confirmed the importance of individual components for the total antioxidant efficacy of plant extracts.…”

Antioxidant efficacy of Kalanchoe daigremontiana bufadienolide-rich fraction in blood plasma in vitro

“…Trolox V R and (À)-epicatechin) were performed at the concentration range of 1.25-20 lg/mL. Experiments were performed accordingly to the protocol described previously (Kolodziejczyk-Czepas et al 2014). The RSAs of the examined fraction and reference compounds were calculated from the following equation: RSA (%) ¼ 100 Â (A 0 À A 1 )/A 0 .…”