title: Variation in saponin content during the growing season of spotted medic [Medicago arabica (L.) Huds.].
abstract: BACKGROUND
  Spotted medic [Medicago arabica (L.) Huds.] is a minor forage species containing saponins which are reported to be biologically active. This study assessed the concentration and composition pattern of spotted medic saponins during the growing season and at senescence. The pattern of saponins was based on identification and quantification of their constituent sapogenins. At senescence, individual saponin concentrations of aerial and subterranean plant organs were also determined.
  
  
  RESULTS
  Leaf total saponin content did not vary during the growing season and decreased remarkably at senescence. Seven sapogenins were identified and quantified during the season, bayogenin and hederagenin being the most abundant ones throughout. Total saponin content varied among plant organs at senescence, with the highest concentration in roots. A variable number of saponins from one (in seeds) to 19 (in leaves) were quantified. A clear relationship between leaf concentrations of sapogenins and those of their derivative saponins was revealed by correlation analysis.
  
  
  CONCLUSIONS
  The species displayed a sapogenins/saponins pattern markedly different from those of other perennial or annual Medicago species. Saponins of queretaroic acid and 2β-hydroxy queretaroic acid had no precedent in the Leguminosae. The high concentration of biologically active hederagenin suggested further assessment of possible effects on feeding animals.
authors.affiliation: CRA-Centre of Research for Fodder Crops and Dairy Productions, Lodi, Italy. luciano.pecetti@entecra.it
authors.forename: Luciano
authors.initials: L
authors.lastname: Pecetti
authors.forename: Elisa
authors.initials: E
authors.lastname: Biazzi
authors.forename: Aldo
authors.initials: A
authors.lastname: Tava
mesh_terms: D016922:Cellular Senescence / Q000502:physiology*; D029902:Medicago / Q000737:chemistry*; D035261:Plant Components, Aerial / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D012502:Sapogenins / Q000032:analysis*; D012503:Saponins / Q000032:analysis*; D012621:Seasons
chemical_list: D012502:Sapogenins; D012503:Saponins