title: Biological activity of clovers - free radical scavenging ability and antioxidant action of six Trifolium species.
abstract: BACKGROUND
  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.
  
  
  METHODS
  Free radical scavenging activity of the extracts (1.5-50 µg/ml) was estimated by reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)) and 2,2'-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.
authors.affiliation: Department of General Biochemistry, Faculty of Biology and Environmental Protection, University of Lodz , Lodz , Poland and.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kolodziejczyk-Czepas
authors.forename: Pawel
authors.initials: P
authors.lastname: Nowak
authors.forename: Iwona
authors.initials: I
authors.lastname: Kowalska
authors.forename: Anna
authors.initials: A
authors.lastname: Stochmal
mesh_terms: D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D029902:Medicago; D035261:Plant Components, Aerial; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D010949:Plasma / Q000187:drug effects* / Q000378:metabolism; D013045:Species Specificity; D029921:Trifolium
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010936:Plant Extracts
keywords: Blood plasma; oxidative stress; peroxynitrite; plant extract; traditional medicine