title: Antioxidant efficacy of Kalanchoe daigremontiana bufadienolide-rich fraction in blood plasma in vitro.
abstract: BACKGROUND
  The main source of bufadienolides is toad venom; however, plants such as members of Kalanchoe Adans. (Crassulaceae) genus may also synthesize these bioactive substances.
  
  
  OBJECTIVE
  This is the first study on antioxidant effects and cytotoxicity of bufadienolide-rich fraction isolated from Kalanchoe daigremontiana Raym.-Hamet & H. Perrier.
  
  
  METHODS
  The methanolic fraction was extracted from the plant roots and contained 0.48 mg bufadienolides/mg of dry mass (11α,19-dihydroksytelocinobufagin, bersaldegenin-1-acetate, bersaldegenin-1,3,5-orthoacetate, 19-(acetyloxy)-3β,5β,11α,14-tetrahydroxyl-12-oxo-bufa-20,22-dienolide and 19-(acetyloxy)-1β,3β,5β,14-tetrahydroxyl-bufa-20,22-dienolide, mainly). The cytotoxicity of K. daigremontiana fraction was evaluated in an in vitro experimental model of blood platelets. The viability of blood platelets was determined on the basis of a release of lactate dehydrogenase.
  
  
  RESULTS
  The fraction scavenged DPPH•radicals, with EC50of 21.80 μg/mL. Studies on an experimental model of blood plasma under peroxynitrite-induced oxidative stress revealed that the plant preparation had moderate antioxidant properties. Levels of 3-nitrotyrosine and thiol groups indicated that the protective effect of K. daigremontiana was significant mainly for its concentration of 50 μg/mL. No effect was found in prevention of oxidation of low-molecular plasma thiols (glutathione, cysteine and cysteinylglycine). Simultaneously, measurements of lipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS) indicated that the examined fraction might be effective antioxidant at broader concentration range, that is 1-5 and 25-50 μg/mL for hydroperoxides and TBARS generation, respectively. No cytotoxicity was observed at the concentration range of 1-50 μg/mL.
  
  
  CONCLUSIONS
  Based on the obtained results, we suggest that antioxidant activity may additionally contribute to beneficial properties of K. daigremontiana-derived extracts.
authors.affiliation: a Department of General Biochemistry, Faculty of Biology and Environmental Protection , University of Lodz , Lodz , Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kolodziejczyk-Czepas
authors.affiliation: a Department of General Biochemistry, Faculty of Biology and Environmental Protection , University of Lodz , Lodz , Poland.
authors.forename: Pawel
authors.initials: P
authors.lastname: Nowak
authors.affiliation: a Department of General Biochemistry, Faculty of Biology and Environmental Protection , University of Lodz , Lodz , Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Wachowicz
authors.affiliation: b Department of Environmental Chemistry, Faculty of Chemistry , University of Lodz , Lodz , Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Piechocka
authors.affiliation: b Department of Environmental Chemistry, Faculty of Chemistry , University of Lodz , Lodz , Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Głowacki
authors.affiliation: c Department of Biochemistry , Institute of Soil Science and Plant Cultivation, State Research Institute , Pulawy , Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Moniuszko-Szajwaj
authors.affiliation: c Department of Biochemistry , Institute of Soil Science and Plant Cultivation, State Research Institute , Pulawy , Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Stochmal
mesh_terms: D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D002018:Bufanolides / Q000302:isolation & purification / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D031962:Kalanchoe; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018517:Plant Roots; D010949:Plasma / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002018:Bufanolides; D010936:Plant Extracts
keywords: Bufadienolide; blood platelets; cytotoxicity; free radical scavenging